Nippon Thompson Co., Ltd. is a bearing manufacturer that launched the technical development of needle roller bearings for the first time in Japan and is proud of the high quality level and abundant varieties of its products. Needle roller bearings are bearings for rotary motion that incorporate needle- shaped thin rollers instead of ordinary bearing balls or rollers. Compared with other rolling bearings, they are small-sized and lightweight but have a large load capacity. They are widely used with high reliability in the fields of automobiles, industrial machinery, OA equipment, etc. as resource-saving type bearings that make the whole machine compact.

A1 A2 A Characteristics of Needle Roller Bearings Bearings can be classified into two main types, namely rolling bearings and sliding bearings. Rolling bearings can be subdivided further into ball bearings and roller bearings according to the rolling elements. Classification of bearings B Needle Roller Bearings are high-precision rolling bearings with a low sectional height, incorporating needle rollers as the rolling element. They have the following features.

Deep groove ball bearings C

Merits of Rolling Bearings Merits of Needle Roller Bearings Angular contact ball bearings Radial ball

bearings Self-aligning ball bearings Compared with sliding bearings, rolling bearings Compared with other rolling bearings, Needle D have the following merits: Roller Bearings have the following advantages: Others

With a low sectional height, they can Thrust ball bearings with flat back face Static and kinetic friction is low. Ball bearings withstand heavy loads. E Thrust ball bearings with aligning seat washer Thrust ball Since the difference between static friction and Since they have a low sectional height compared bearings Double-direction angular contact thrust ball bearings kinetic friction is small and the frictional coefficient is with other rolling bearings and yet can withstand also small, drive units or machines can be made heavy loads, machines can be made more compact Others more compact and lightweight, saving machine costs and lightweight, thus saving costs. F and power consumption. Needle roller bearings Bearings Stable accuracy can be maintained Rotating torque is small, improving Cylindrical roller bearings G

for long periods. mechanical efficiency. Rolling bearings Radial roller Tapered roller bearings bearings Owing to less wear, stable accuracy can be Since the rotating radius is small, the rotating torque maintained for long periods. is also small under the same frictional conditions, Self-aligning roller bearings thus improving mechanical efficiency. Others H

Machine reliability is improved. Inertia is minimized.

Roller bearings Thrust needle roller bearings

Thrust cylindrical roller bearings I Since the bearing life can be estimated based on Since the bearing volume and weight are small, the Thrust roller rolling fatigue, machine reliability is improved. moment of inertia of the bearing is minimized when it bearings Thrust tapered roller bearings is put in motion. Others J Lubrication is simplified. Most suited to oscillating motions.

Since grease lubrication is sufficient in most cases, Many rolling elements are arranged at a small Metals, bushings, others lubrication can be simplified for easy maintenance. spacing pitch, and this configuration is most suited to K oscillating motions. Sliding bearings L

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A3 A4 A Types and Features of Bearings Bearings can be roughly classified into radial bearings and thrust bearings according to applicable load direction. Crossed Roller Bearings are special shape bearings that can simultaneously receive loads in all directions with a Radial Bearings are grouped into Shell Type Needle Roller Bearings, Machined Type Needle Roller Bearings, and single bearing. various other types. Thrust Bearings are grouped into Thrust Needle Roller Bearings and Thrust Roller Bearings. Bearings other than rolling bearings, such as self-aligning Spherical Bushings that can support radial loads and B Follower Bearings that are used for cam mechanisms and linear motion are grouped into Cam Followers and Roller axial loads and PILLOBALLs and L-Balls that are used for link mechanisms, are also available. Followers.

Classification of Bearings C TA、TAM C-Lube Cam Followers TLA、TLAM BA、BAM D Shell Type BHA、BHAM Needle Roller Bearings YT YTL YB E YBH Cylindrical Roller Cam Followers

KT Needle Roller Cages for General Usage Thrust Disk Type Miniature Cam Followers KTW Needle Roller Cages Miniature Type Cam Followers Stainless Steel Made F KT…EG Needle Roller Cages for Engine Connecting Rods KTV…EG

C-Lube Machined Type Needle Roller Bearings TAF…/SG NA、RNA G TAFI、TAF Cylindrical Roller Followers Radial Bearings TRI、TR Machined Type BRI、BR Needle Roller Bearings H GTRI、GTR GBRI、GBR NAF、RNAF Needle Roller Bearings with Separable Cage NAFW、RNAFW I NAU NAG Roller Bearings TRU J Roller Bearings for Sheaves NAS

Thrust Needle Roller Bearings NTB Thrust

Bearings K Thrust Roller Bearings AZK、AZ

with Thrust Ball Bearing NAXI、NAX Combined Type with Thrust Roller Bearing NBXI、NBX L Needle Roller Bearings with Angular Contact Ball Bearing NATA Bearings

Combined Type with Three-point Contact Ball Bearing NATB M

A5 A6 A

Shell Type Needle Roller Bearings Machined Type Needle Roller Bearings B Shell Type Needle Roller Bearings are lightweight with Machined Type Needle Roller Bearings have an outer the lowest sectional height among needle roller bearings ring made by machining, heat treatment, and grinding. with outer ring, because they employ a shell type outer The outer ring has stable high rigidity and can be easily ring made from a thin special-steel plate which is used even for light alloy housings. C accurately drawn, carburized and quenched. These bearings are available in various types and Since these bearings are press-fitted into the housing, optimally selectable for different conditions such as no axial positioning fixtures are required. They are ideal heavy loads, high-speed rotation and low-speed rotation. for use in mass-produced articles that require economy. They are most suitable for general-purpose applications. D

Radial Bearings Page B1 Radial Bearing Page D1 E

Needle Roller Cages for General Usage Needle Roller Bearings with Separable Cage

Needle Roller Cages for General Usage are bearings In Needle Roller Bearings with Separable Cage, the F that display excellent rotational performance. Their inner ring, outer ring and Needle Roller Cage are specially shaped cages with high rigidity and accuracy, combined, and they can be separated easily. This type precisely guide the needle rollers. has a simple structure with high accuracy. In addition, Since needle rollers with extremely small dimensional the radial clearance can be freely selected by choosing variations in diameter are incorporated and retained, an assembly combination. G Needle Roller Cages for General Usage are useful in These bearings have excellent rotational performance, small spaces when combined with shafts and housing because Needle Roller Cages are used. bores that are heat treated and accurately ground as raceway surfaces. H

Radial Bearing Page C1 Radial Bearing Page D93 I

Needle Roller Cages for Engine Connecting Rods Roller Bearings

Needle Roller Gages for Engine Connecting Rods are Roller Bearings, in which rollers are incorporated in used for motor cycles, small motor vehicles, outboard double rows, are non-separable heavy-duty bearings. J marines, snow mobiles, general-purpose engines, high- They can withstand not only radial loads but axial loads speed compressors, etc. that are operated under as well, which are supported at the contacts between the extremely severe and complex operating conditions such shoulders of inner and outer rings and the end faces of as heavy shock loads, high speeds, high temperatures, rollers. Therefore, they are most suitable for use at the and stringent lubrication. fixing side of a shaft. K Needle Roller Cages for Engine Connecting Rods are lightweight and have high load ratings and high rigidity as well as superior wear resistance. L Radial Bearing Page C17 Radial Bearing Page E1

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A7 A8 A

Thrust Bearings Cam Followers B Thrust Bearings consist of a precisely made cage and Cam Followers are bearings with a stud incorporating rollers, and can receive axial loads. They have high needle rollers in a thick walled outer ring. rigidity and high load capacities and can be used in They are designed for outer ring rotation, and the outer small spaces. rings run directly on mating track surfaces. C Thrust Needle Roller Bearings use needle rollers, while Various types of Cam Followers are available. They are Thrust Roller Bearings use cylindrical rollers. widely used as follower bearings for cam mechanisms and for linear motions. D

Thrust Bearing Page F1 Follower Bearing Page I1 E

Combined Type Needle Roller Bearings Roller Followers

Combined Type Needle Roller Bearings are Roller Followers are bearings in which needle rollers are F combinations of a radial bearing and a thrust bearing. incorporated in a thick walled outer ring. Caged Needle Roller Bearings are used as radial These bearings are designed for outer ring rotation, and bearings and Thrust Ball Bearings or Thrust Roller the outer rings run directly on mating track surfaces. Bearings are used as thrust bearings. They are used as follower bearings for cam mechanisms They can be subjected to radial loads and axial loads and for linear motions. G simultaneously. H

Combined Type Bearing Page G1 Follower Bearing Page I71 I

Inner Rings Crossed Roller Bearings

Inner Rings are heat-treated and finished by grinding to Crossed Roller Bearings are high-rigidity and compact a high degree of accuracy and are used for Needle bearings with their cylindrical rollers alternately crossed J Roller Bearings. at right angles to each other between inner and outer In the case of Needle Roller Bearings, normally the rings. A single Crossed Roller Bearing can take loads shafts are heat-treated and finished by grinding and from any directions at the same time such as radial, used as raceway surfaces. However, when it is thrust, and moment loads. impossible to make shaft surfaces according to the These bearings are widely used in the rotating parts of K specified surface hardness or surface roughness, Inner industrial robots, machine tools, medical equipment, etc. Rings are used. which require compactness, high rigidity and high rotational accuracy. L Component part Page H1 Crossed Roller Bearing Page J1

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A9 A10 A

Spherical Bushings Seals for Needle Roller Bearings B Spherical Bushings are self-aligning spherical plain Seals for Needle Roller Bearings have a low sectional bushings, which have inner and outer rings with height and consist of a sheet metal ring and special spherical sliding surfaces. They can take a large radial synthetic rubber. load and a bi-directional axial load at the same time. As these seals are manufactured to the same sectional C They are divided into steel-on-steel types that are height as Needle Roller Bearings, grease leakage and suitable for applications where there are alternate loads the penetration of foreign particles can be effectively or shock loads, and maintenance-free types which prevented by fitting them directly to the sides of require no lubrication. combinable bearings. D

Spherical Sliding Bearing Page K1 Component Part Page L1 E

PILLOBALLs Cir-clips for Needle Roller Bearings

PILLOBALLs are compact self-aligning spherical plain Cir-clips for Needle Roller Bearings have been specially F bushings which can support a large radial load and a bi- designed for needle roller bearings on which, in many directional axial load at the same time. cases, generally available Cir-clips cannot be used. PILLOBALL Rod Ends have either a female thread in the They have a low sectional height and are very rigid. body or a male thread on the body, so they can be easily There are Cir-clips for shafts and for bores, and they are assembled onto machines. used for positioning to prevent bearing movement in the G PILLOBALLs are used in control and link mechanisms in axial direction. machine tools, textile machines, packaging machines, etc. H

Spherical Sliding Bearing Page K29 Component Part Page L17 I

L-Balls Needle Rollers

L-Balls are self-aligning rod-ends consisting of a special Needle Rollers are used for needle roller bearings and die-cast zinc alloy body and a studded ball which has its are rigid and highly accurate. J axis at right-angles to the body. These needle rollers are widely used as rolling elements They can perform tilting movement and rotation with low for bearings, and also as pins and shafts. torque, and transmit power smoothly due to the uniform clearance between the sliding surfaces. They are used in link mechanisms in automobiles, K construction machinery, farm and packaging machines, etc. L Spherical Sliding Bearing Page K45 Component Part Page L23

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A11 A12 A Features of Bearings

Direction of Load direction Allowable Sectional Reference Direction of Load direction Allowable Sectional Reference Bearing series Appearance motion and capacity rotational speed Friction height page Bearing series Appearance motion and capacity rotational speed Friction height page B

Needle roller Caged type bearings

Shell Type Thrust . Needle Roller B1 ～ Bearings ～ Bearings C Full complement Roller type bearings D With For C1 ～ thrust general usage ball bearing Needle Roller Cages E For engine With connecting C17 ～ thrust rods roller bearing Combined Type Needle Roller / ～ Bearings With F Caged type angular contact ball bearing Machined Type Needle Roller D1 ～ Bearings With Full three-point G complement contact type ball bearing

Needle Roller H Bearings with Caged type D93 ～ Caged type Separable Cage

Cam Followers 1 ～

Full Caged type complement I type

Full Separable Roller Bearings complement E1 ～ type caged type J

Non-separable 1% For sheaves Roller Followers caged type ～ K

Oscillating Radial Axial Light Medium Heavy Especially Non-separable Symbol Rotation motion load load load load load excellent Excellent Normal full complement type L

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A13 A14 A Features of Bearings Outline of Bearing Selection Bearings are available in many types and sizes. To obtain satisfactory bearing performance in machines and Direction of Load direction Allowable Sectional Reference Bearing series Appearance motion and capacity rotational speed Friction height page equipment, it is essential to select the most suitable bearing by carefully studying the requirements for the application. Although there is no particular procedure or rule for bearing selection, an example of a commonly adopted procedure B is shown in the figure below. Caged type, Separator type An example of procedure for bearing selection C ● Identify the machine and place where the bearing is to be used. Full Confirmation of Crossed ● Confirm the requirements for bearings such as required bearing complement J1 ～ requirements and Roller Bearings type 1 performance, and also confirm the operating conditions and special operating conditions environment conditions. D ● Select the bearing type suitable for the operating Slim type conditions by considering load direction and magni- See page Selection of bearing type 2 tude, rigidity, friction, allowable rotational speed, bearing A5 space, etc. E Steel-on-steel ● Select the bearing dimensions by calculating bearing type Selection of load, life, static safety factor, etc. See page Spherical 3 bearing dimensions A17 Bushings K1 ～ F Maintenance-free type ● Select the accuracy as required by the machine or Selection of equipment. See page 4 accuracy class, etc. A30

Insert type, G Lubrication type ● Select the radial clearance considering the fit, Selection of temperature, rotational speed, inclination of the inner See page 5 radial clearance and fit and outer rings, etc. A37 Die-casting type, H PILLOBALLs Lubrication type K29 ～ 6 Determination of bearing dimensions, accuracy, radial clearance and fit Maintenance-free I type

Selection of ● Select oil or grease lubrication. ● After selection of lubricant, in case of oil lubrication, See page lubrication and select the oil application method. 7 dust-proof methods A49 L-Balls Lubrication type K45 ～ ● Select the sealing method according to the lubricant. J

● Design the surrounding part based on how to mount Design of or dismount and based on mounting dimensions. See page Oscillating Radial Axial Light Medium Heavy Especially Symbol Rotation Excellent Normal motion load load load load load excellent 8 surrounding part A57 K

9 Determination of final specifications of the bearing and the surrounding part L

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A15 A16 Basic Dynamic Load Rating Basic rating life A

and Life The basic rating life is defined as the total number of Rotational speed revolutions that 90% of a group of identical bearings Velocity factor Life can be operated individually under the same condi- B tions free from any material damage caused by rolling Basic rating life represented by service hours Rolling bearings will suffer damage due to various fatigue. Life factor causes during service. Damage such as abnormal For rotation at a constant rotational speed, the basic wear, seizure, and cracks is caused by improper use, rating life can be represented by the total service including incorrect mounting, lack of oil, dust intrusion hours. C and so on, and can be avoided by remedying these causes. However, bearings will eventually be dam- Basic dynamic load rating Rotational speed aged due to fatigue-flaking even if used properly. Velocity factor When a bearing rotates under load, the raceways and The basic dynamic load rating is defined as the con- D the rolling elements are subjected to repeated stress- stant radial load (in the case of radial bearings) or the Basic rating life represented by service hours es concentrated on the part close to the surface. constant axial load acting along the bearing central Life factor Fatigue, therefore, occurs in the surface layer, pro- axis (in the case of thrust bearings) that allows a ducing damage in the form of scaling. This is called basic rating life of 1,000,000 revolutions. flaking (spalling). When this occurs, the bearing can Fig. 2 Scales for rating life calculation E no longer be used. Calculation of rating life

Bearing Life The relationship among the basic rating life, basic dynamic load rating and dynamic equivalent load F Bearing life is defined as the total number of revolu- (bearing load) of rolling bearings is as follows: Bearing life factors for various machines tions (or total service hours at a constant rotational C p L ＝ ……………………………………(1) speed) before a sign of the first flaking appears on the 10 （）P The required life of the bearing must be determined rolling surface of raceway or rolling elements. 6 according to the machine in which the bearing is to be where, L10 ： Basic rating life, 10 rev. G However, even when bearings of the same size, C ： Basic dynamic load rating, N used and the operating conditions. Table 1 shows reference values of life factors for structure, material and heat treatment are subjected P ： Dynamic equivalent load, N to the same conditions, the bearing lives will show selecting a bearing for each machine. p ：Exponent, Roller bearing: 10/3 variation (See Fig. 1.). This results from the statistical Ball bearing: 3 nature of the fatigue phenomenon. H Accordingly, when the rotational speed per minute is Table 1 Life factor of bearings f h for various machines In selecting a bearing, it is incorrect to take an aver- given, the basic rating life is represented as the total Machine and life factor f age life for all bearings as the design standard. It is h service hours according to the following equations: Operating conditions ～ 3 2 ～ 4 3 ～ 5 4 ～ 7 6 ～ more practical to consider a bearing life that is reliable 6 10 L10 p for the greater proportion of bearings used. L 500 f (2) Occasional or short term usage ・ Power tools ・ Agricultural machines h ＝＝60n h …………………… I Therefore, the basic rating life defined in the following is used. C f h ＝f n …………………………………(3) Infrequent usage but requiring ・ Construction machinery ・ Conveyors P reliable operation ・ Elevators 33.3 1/p f ＝ …………………………………(4) Intermittent operation but for ・ Roll neck of rolling mills ・ Small motors ・ Factory motors ・ Crane sheaves n （）n J comparatively long periods ・ Deck cranes ・ Machine tools ・ Compressors where, Basic rating life represented by L h ： ・ General cargo cranes ・ General gear units ・ Important gear units service hours, h ・ Passenger cars ・ Printing machines n ： Rotation speed, rpm Operated in excess of 8 hours ・ Escalators ・ Centrifugal separators ・ Paper making machines f ： Life factor h per day or continuously for an ・ Blowers K Velocity factor f n ： extended time ・ Wood working machines In addition, the rating life can be calculated by obtain- ・ Plastic extruding machines ing f h and f n from the life calculation scales of Fig. 2. Continuous use for 24 hours and ・ Water supply equipment accidental stops not allowed ・ Power station equipment L

Fig. 1 Variation of rolling fatigue life M

1N=0.102kgf=0.2248lbs. A17 1mm=0.03937inch A18 bearing life adjustment factors a , a and a , respec- Life of oscillating bearing 1 2 3 Life adjustment factor for operating conditions a3 Correction of basic dynamic load rating A tively. for temperature and hardness The life of an oscillating bearing can be obtained from This factor helps take into account the effects of oper- L na ＝ a1a2a3L 10 …………………………… (6) equation (5). ating conditions, especially lubrication on the bearing. Temperature factor p 6 90 C where, L na ： Corrected rating life, 10 rev. The bearing life is limited by the phenomenon of LOC ＝ ………………………………(5) B θ（）P a1 ： Life adjustment factor for reliability fatigue which occurs, in general, beneath surfaces The operating temperature for each bearing is deter- subjected to repeated stresses. Under good lubrica- mined according to its material and structure. If spe- where, L OC ：Basic rating life of oscillating a2 ：Life adjustment factor for special bearing, 106 cycles bearing properties tion conditions where the rolling element and raceway cial heat treatment is performed, bearings can be surfaces are completely separated by an oil film and used at temperatures higher than +150 °C. However, 2θ ： Oscillating angle, deg. (See Fig.3) a3 ：Life adjustment factor for operat- surface damage can be disregarded, a is set to be 1. the allowable contact stress decreases gradually as P ： Dynamic equivalent load, N ing conditions 3 C However, when conditions of lubrication are not good, the operating temperature increases. Accordingly, Therefore, when the oscillating frequency n 1cpm is namely, when the viscosity of the lubricating oil is low the basic dynamic load rating is lowered and can be given, the basic rating life as represented by total Life adjustment factor for reliability a1 or the peripheral speed of the rolling elements is obtained by the following equation: oscillating hours can be obtained by substituting n 1 especially low, and so on, a3< 1 is used. for n in equation (2) on page A17. The reliability of rolling bearings is defined as the pro- f C (7) D On the other hand, when lubrication is especially C t ＝ t …………………………………… When 2θ is small, an oil film cannot be formed easily portion of bearings having a life equal to or greater good, a value of a > 1 can be used. When lubrica- between the contact surfaces of the raceway and the than a certain specified value when a group of identi- 3 where, C t ：Basic dynamic load rating tion is not good and a < 1 is used, the life adjustment rolling elements. This may cause fretting corrosion. cal bearings are operated under identical conditions. 3 considering temperature rise, N factor a2 cannot generally exceed 1. In this case, please consult . With respect to individual bearings, it refers to the f t ： Temperature factor (See Fig. 4.) E probability of the life of a bearing being equal to or C ： Basic dynamic load rating, N When selecting a bearing according to the basic greater than a certain specified value. dynamic load rating, it is recommended that a suitable The corrected rating life for a reliability of (100-n)% value for reliability factor a is chosen for each appli- can be obtained using equation (6). Table 2 shows 1 cation. The selection should be made using the the values of the life adjustment factor a1 for various F (C/P) or f values determined by machine type and reliabilities. h based upon the actual conditions of lubrication, tem- perature, mounting, etc., which have already been Table 2 Life adjustment factor for reliability a1 experienced and observed in the same type of Fig. 4 Temperature factor machines. G Reliability ％ L n a 1 Hardness factor Fig. 3 Oscillating motion 90 L 10 1 Limiting conditions 95 L 5 0.62 When the shaft or housing is used as the raceway 96 L 4 0.53 These bearing life equations are applicable only when H surface instead of the inner or outer ring, the surface 97 L 3 0.44 the bearing is mounted and lubricated normally with- hardness of the part used as the raceway surface Corrected rating life 98 L 2 0.33 out intrusion of foreign materials and not used under L should be 58 64HRC. 99 1 0.21 extreme operating conditions. ～ If it is less than 58HRC, the basic dynamic load rating When a rolling bearing is used in ordinary applica- Unless these conditions are satisfied, the life may be is lowered and can be obtained by the following equa- I tions, the basic rating life can be calculated by equa- Life adjustment factor for special bearing properties a2 shortened. For example, it is necessary to separately tion: tions (1) and (2) mentioned previously. consider the effects of bearing mounting errors, This basic rating life applies to bearings which require The bearing life is extended or shortened according to excessive deformation of housing and shaft, centrifu- C H ＝ f H C …………………………………… (8) a reliability of 90%, have ordinary bearing properties the quality of the material, the manufacturing technol- gal force acting on rolling elements at high-speed rev- being made of materials of ordinary quality for rolling ogy of the bearing and its internal design. For these olution, excessive preload, especially large radial where, C H ：Basic dynamic load rating J bearings, and are used under ordinary operating con- special bearing life properties, the life is corrected by internal clearance of radial bearings, etc. considering hardness, N ditions. the life adjustment factor for special bearing proper- When the dynamic equivalent load exceeds 1/2 of the f H ： Hardness factor (See Fig. 5.) In some applications, however, it is necessary to ties a2. basic dynamic load rating, the life equations may not C ： Basic dynamic load rating N obtain a rating life that applies to bearings which The table of dimensions for Bearings shows the be applicable. K require high reliability, have special bearing properties values of the basic dynamic load rating which are or are used under special operating conditions. The determined taking into consideration the fact that corrected rating life for these special cases can be bearing life has been extended by improved quality of obtained from the following equation by using the materials and advances in manufacturing technolo- gies. Therefore, the bearing life is calculated using L equation (6) usually assuming a2 = 1.

Fig. 5 Hardness factor M

1N=0.102kgf=0.2248lbs. A19 1mm=0.03937inch A20 Basic Static Load Rating and Static safety factor Calculation of Bearing Loads Load factor A

Static Safety Factor The basic static load rating gives the theoretical allow- The loads acting on bearings include the weight of the Although radial loads and axial loads can be obtained able limit of the static equivalent load. Normally, this machine parts supported by the bearings, the weight by calculation, it is not unusual for the actual bearing Basic static load rating limit is corrected by considering the operating condi- of the rotating body, loads produced when operating loads to exceed the calculated loads, due to vibration B tions and the requirements for the bearing. The cor- the machine, loads by belts or gears transmitting and shocks produced when operating the machine. When a bearing at rest sustains a heavy load or a rection factor, namely, the static safety factor f s is power, and various other loads. The actual bearing load is obtained from the following bearing rotating at a relatively low speed receives a defined as in the following equation and its general These loads can be divided into radial loads perpen- equation, by multiplying the calculated load by the heavy shock load, the contact stress may exceed a values are shown in Table 4. dicular to the central axis of the bearings and axial load factor: certain limiting value, producing a local permanent C 0 loads parallel to the central axis, and they act inde- C f s ＝ ………………………………………(9) F ＝ f wFc ……………………………………(10) deformation in the raceways or the rolling elements, P 0 pendently or in combination with other loads. In addi- and subsequently causing noise or vibration or lower- where, C 0 ：Basic static load rating, N tion, the magnitude of vibration or shocks on the bear- where, F ： Bearing load, N ing the rotating performance. The basic static load P 0 ： Static equivalent load, N ings varies depending on the application of the fw ： Load factor (See Table 6.) rating is, therefore, determined as a guideline for the machine. Thus, theoretically calculated loads may Fc ： Theoretically calculated load, N D maximum allowable load for the bearing at rest, under Table 4 Static safety factor not always be accurate and have to be corrected by which the permanent deformation will not exceed a multiplying various empirical factors to obtain the Table 6 Load factor certain limit value, and the lowering of the rotating Operating conditions of the bearing f s actual bearing loads. performance will not occur. Its definition is given as Operating conditions Example fw follows. When high rotational accuracy is required ≧ 3 E The basic static load rating is the static load that gives For ordinary operation conditions ≧ 1.5 Smooth operation Electric motors, Air conditioning equipment, Load distribution to bearings 1 ～ 1.2 without shocks Measuring instruments, Machine tools the contact stress shown in Table 3 at the center of For ordinary operation conditions not the contact area of the rolling element and the race- requiring very smooth rotation ≧ 1 Table 5 shows examples of calculations where static Reduction gearboxes, Vehicles, Textile Ordinary operation 1.2 ～ 1.5 way receiving the maximum load. A radial load con- When there is almost no rotation loads are acting in radial direction. machinery, Paper making machinery F stant in direction and magnitude is used in the case of Operation subjected to Rolling mills, Rock crushers, Construc- radial bearings, while an axial load constant in magni- 1.5 ～ 3 vibration and shocks tion machinery tude acting along the bearing central axis is used in In case of Shell Type Needle Roller Bearings of which the case of thrust bearings. outer ring is drawn from a thin steel plate and then carburized and quenched, it is necessary to use a sta- G Table 3 tic safety factor of 3 or more.

Type of bearing Contact stress MPa Table 5 Load distribution to bearings H Roller bearings 4000 Example Bearing load Self-aligning ball bearings 4 600 Other ball bearings 4 200 I dK r1＋bK r2 F r1= f

cK r1＋aK r2 F r2= f J

K

gK ＋bK －cK F = r1 r2 r3 r1 f

aK ＋dK －eK L F = r2 r3 r1 r2 f M

1N=0.102kgf=0.2248lbs. A21 1mm=0.03937inch A22 H Bearing loads in case of belt or chain transmission T= 9550000 ……………………………(14) Mean equivalent load corresponding to fluctuating load N n p 1 p A F m = F n dN ……………………(19) N∫0 When power is transmitted by a belt or chain, the load T √ K t = ……………………………………(15) When the load applied to the bearing fluctuates, the R acting on the pulley or sprocket wheel is obtained bearing life is calculated by using the mean equivalent where, F m： Mean equivalent load, N from the following equations: load Fm, which is a constant load that will give the N ： Total number of revolutions, rev. K s = K t tan θ ………………………………(16) B bearing a life equal to that produced under the fluctu- F ： Fluctuating load, N H n T= 9550000 ……………………………(11) 22 ating load. The mean equivalent load is obtained p ：Exponent, Roller bearing = 10/3 n K c =√K t ＋K s = K t sec θ …………………(17) from the following equation: Ball bearing = 3 T K = ……………………………………(12) t R where, T ： Torque applied to gear, N-mm Table 9 shows examples of the calculation of mean C K t： Tangential force acting on gear, N where, T ：Torque acting on pulley or sprocket equivalent loads for various fluctuating loads. K s： Radial force acting on gear, N wheel, N-mm K c： Resultant normal force on gear tooth surface, N K ： Effective transmitting force of belt or chain, N t H ： Transmitting power, kW H ： Transmitting power, kW D n ： Rotational speed, rpm Table 9 Mean equivalent load for the fluctuation load n ：Rotation speed, rpm R ： Pitch circle radius of drive gear, mm R ：Effective radius of pulley or Type of fluctuating load Mean equivalent load F m θ： Pressure angle of gear, deg. sprocket wheel, mm E p 1 p pp For belt transmission, the load K r acting on the pulley F m =(F 1 N 1 ＋F 2 N 2 ＋…＋F n N n) shaft is obtained from the following equation, multiply- √N ing the effective transmitting force K t by the belt factor Step load where, N 1 ： Total number of revolutions under load F 1 rev. f b shown in Table 7. N 2 ： Total number of revolutions under load F 2 rev. F N n ： Total number of revolutions under load Fn rev. K r = f bK t ………………………………………(13)

Table 7 Belt factor 1 G F m =(2F max ＋ F min ) 3 Type of belt f b Monotonously changing load where, F ： Maximum value of fluctuating load, N V-belts 2 ～ 2.5 max Fig. 6 F min ： Minimum value of fluctuating load, N Timing belts 1.3 ～ 2 H Plain belts (with tension pulley) 2.5 ～ 3 In this case, the resultant normal force on the tooth Plain belts 4 ～ 5 surface acts as the radial force to the shaft and the magnitude of vibration or shocks varies depending on In the case of chain transmission, a value of 1.2 to 1.5 the accuracy and surface finish of the gear. F ≒ 0.65F I Therefore, the radial load K applied to the shaft is m max is taken as the chain factor corresponding to f b. The r load acting on the sprocket wheel shaft is obtained obtained from the following equation, multiplying the from equation (13) in the same manner as the belt resultant normal force K c on gear tooth surface by the Sinusoidally transmission. gear factor fz shown in Table 8. fluctuating load J

Bearing loads in case of gear transmission K r = f z K c ……………………………………(18) F m ≒ 0.75F max

When power is transmitted by gears, the force acting Table 8 Gear factor on the gears varies according to the type of gear. K Type of gear f z Spur gears produce radial loads only, but helical F S F R gears, bevel gears and worm gears produce axial F = F ＋ F － Precision gears m S R F F 1.05 ～ 1.1 S ＋ R loads in addition to radial loads. Taking the simplest (Pitch error and form error: Less than 0.02mm) Stationary load plus case of spur gears as an example, the bearing load is rotating load where, F S ： Stationary load, N Ordinary machined gears L obtained from the following equations: 1.1 ～ 1.3 F R ： Rotating load, N (Pitch error and form error: 0.02 ～0.1mm) M

1N=0.102kgf=0.2248lbs. A23 1mm=0.03937inch A24 Equivalent load Static equivalent load Boundary Dimensions and Needle Roller Cage A

The loads applied to the bearing are divided into radi- When both radial load and axial load are applied to Identification Number E w ： Nominal roller set outside diameter the bearing simultaneously, the virtual load, acting on al loads that are applied perpendicular to the central F w ： Nominal roller set bore diameter the center of the bearing, that will produce a maxi- axis and axial loads that are applied in parallel to the Boundary dimensions B c ：Nominal cage width central axis. These loads act independently or in com- mum contact stress on the contact surface between B bination with other loads. the rolling element and the raceway equal to that Examples of symbols for quantities indicating the given by the radial load and the axial load is defined boundary dimensions of Needle Roller Bearings Dynamic equivalent load as a static equivalent load. are shown below. For details, see the table of dimen- In the case of needle roller bearings, radial bearings sions for each model. C When both radial load and axial load are applied to receive only radial loads and thrust bearings receive the bearing simultaneously, the virtual load, acting on only axial loads. Accordingly, radial loads are directly Machined Type Needle Roller Bearing the center of the bearing, that will give a life equal to used for the radial bearings, while axial loads are directly used for the thrust bearings. that under the radial load and the axial load is defined d ： Nominal bearing bore diameter D as a dynamic equivalent load. D ： Nominal bearing outside diameter [For radial bearings] In the case of needle roller bearings, radial bearings B ： Nominal inner ring width P = F ………………………………………(22) receive only radial loads and thrust bearings receive 0r r C ： Nominal outer ring width only axial loads. Accordingly, radial loads are directly [For thrust bearings] F w ： Nominal roller set bore diameter used in the life calculation of the radial bearings, while P 0a= Fa ………………………………………(23) Fig. 9 Needle Roller Cage E r ： Chamfer dimensions of inner and outer rings axial loads are directly used for the thrust bearings. r smin：Smallest permissible single chamfer where, P ： Static equivalent radial load, N 0r dimensions of inner and outer rings [For radial bearings] P 0a ： Static equivalent axial load, N Thrust Roller Bearing P r = F r ………………………………………(20) F r ：Radial load, N F [For thrust bearings] D ： Nominal cage outside diameter F a ： Axial load, N c P a= F a ………………………………………(21) d c ： Nominal cage bore diameter D w ： Nominal roller diameter where, P r： Dynamic equivalent radial load, N G Pa：Dynamic equivalent axial load, N F r ： Radial load, N F a： Axial load, N H

Fig. 7 Machined Type Needle Roller Bearing I Shell Type Needle Roller Bearing

D ： Nominal bearing outside diameter F w： Nominal roller set bore diameter C ： Nominal outer ring width J

Fig. 10 Thrust Roller Bearing K

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Fig. 8 Shell Type Needle Roller Bearing M

A25 A26 Identification Number 4 Cage symbol 8 Classification symbol A

The identification number of Bearings consists Symbol Descriptions Symbol Descriptions of a model number and supplemental codes. The N Made of synthetic resin (None) JIS Class 0 descriptions of typical codes and their arrangements B are shown below. There are many codes other than V No cage or full complement P6 JIS Class 6 those described. See the section of identification P5 JIS Class 5 number of each bearing. 5 Seal or shield symbol P4 JIS Class 4 Table 10 Arrangement of identification number of bearing C Symbol Descriptions Model code 1 Model number Table 11 Indication of boundary dimensions Z With dust cover Boundary dimensions 2 Model number ZZ With shields on both sides Material symbol 3 Bearing type Model code Indication of boundary dimensions D U With a seal on one side Cage symbol 4 TA，TLA，YT，YTL Roller set bore diameter + Outer ring width Shell Type Needle Roller Bearings Shield symbol UU With seals on both sides (1) 5 BA，BHA，YB，YBH Roller set bore diameter + Outer ring width Supplemental Seal symbol, code 2RS With seals on both sides Needle Roller Cages for General Usage KT，KTW Roller set bore diameter + Roller set outside diameter + Cage width E Bearing ring shape symbol 6 Needle Roller Cages for Engine Connecting Rods KT … EG，KTV … EG Roller set bore diameter + Roller set outside diameter + Cage width Clearance symbol 7 NA，RNA Dimension series + Bore diameter number 6 Bearing ring shape symbol TR，TAF，GTR Roller set bore diameter + Bearing outside diameter + Bearing width Classification symbol 8 Symbol Descriptions Machined Type Needle Roller Bearings TRI，TAFI，GTRI Bearing bore diameter + Bearing outside diameter + Outer ring width F BR，GBR Roller set bore diameter + Bearing outside diameter + Bearing width (1) 1 Model code NR With stop ring on outer surface of outer ring BRI，GBRI Bearing bore diameter + Bearing outside diameter + Outer ring width (1) The model code represents the bearing series. The Roller set bore diameter + Bearing outside diameter + Bearing width OH(1) With oil hole in bearing ring RNAF，RNAFW features of each bearing series are shown on pages Needle Roller Bearings with Separable Cage NAF，NAFW Bearing bore diameter + Bearing outside diameter + Bearing width A5 to A15. J No oil hole NAU，NAG，NAS Dimension series + Bore diameter number G 1 Roller Bearings Note( ) This differs depending on the type of bearing. See the TRU Bearing bore diameter + Bearing outside diameter + Bearing width 2 Boundary dimensions section of each bearing. NTB，AS，WS，GS Bearing bore diameter + Bearing outside diameter One of the following four kinds of presentation meth- Thrust Bearings AZ Bearing bore diameter + Bearing outside diameter + Bearing height ods is used for showing boundary dimensions in the 7 Clearance symbol AZK Bearing bore diameter + Bearing outside diameter + Roller diameter H identification number, which vary depending on the NAX NBX Roller set bore diameter + Assembled bearing width bearing series. Table 11 shows the presentation Symbol Descriptions ， methods of boundary dimensions for each model Combined Type Needle Roller Bearings NAXI，NBXI Innerring bore diameter + Assembled bearing width code. C2 C2 clearance NATA，NATB Dimensional series + Bore diameter number CF，NUCF，CFS Stud diameter I (None) CN clearance Cam Followers (a)Dimension series + Bore diameter number CR，CRH Bearing outside diameter (1) (b)Bore diameter or roller set bore diameter + C3 C3 clearance NAST，NART，NURT Bearing bore diameter Roller Followers Outside diameter or roller set outside diameter + C4 C4 clearance CRY Bearing outside diameter (1) Width Crossed Roller Bearings CRBH，CRB，CRBS，CRBT Bearing bore diameter + Bearing width J C5 C5 clearance (c)Bore diameter or roller set bore diameter + Width SB… A，GE Inner ring bore diameter Spherical Bushings (d)Basic diameter T1 SBB Inner ring bore diameter (1) Special radial clearance C1 PILLOBALLs PB PHS POS PHSB,POSB,PHSA Inner ring bore diameter (Applicable to Crossed Roller Bearings) , , , 3 Material symbol Screw size C2 L-Balls LHSA，LHS K Seals for Needle Roller Bearings OS，DS Shaft diameter + Seal outside diameter + Seal width Symbol Type of material WR Shaft diameter Cir-clips for Needle Roller Bearings F Stainless steel for bearing rings and rolling elements AR Bore diameter Note(1) The nominal dimensions of inch series bearings are indicated in units of 1/16 inch. L

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1N=0.102kgf=0.2248lbs. A27 1mm=0.03937inch A28 Accuracy A Example of identification number The accuracy of Needle Roller Bearings con- (a) Example of "Dimension series + Bore diameter number" (b) Example of "Bore diameter or roller set bore diameter + Remarks forms to JIS B 1514:2000 (Tolerances of Rolling Outside diameter or roller set outside diameter + width" The meanings of the new symbols for quantities Bearings), and the dimensional accuracy and rotation- B al accuracy are specified. The specified items are used for accuracy of radial bearings are as Supplemental Supplemental shown in Fig. 11. follows: Model number code code Model number Needle Roller Bearings are classified into 4 classes of ①∆ represents the deviation of a dimension from NA49 02 C2 P6 KT5 8 8 N accuracy. These classes are represented by the the specified value. numbers 0, 6, 5 and 4, written in order of increasing ②V represents the variation of a dimension. C Model code Model code accuracy. ③Suffixes s, m, and p represent a single (or Table 12 shows the accuracy for the inner rings of actual) measurement, a mean measurement, Dimension series Roller set bore diameter radial bearings, Table 13 shows the accuracy for the and a measurement in a single radial plane, Bore diameter number Roller set outside diameter outer rings of radial bearings, Table 14 shows the tol- respectively. D erances for the smallest single roller set bore diame- [Example] Vdp means the difference between Clearance symbol Cage width ter of radial bearings, and Table 15 shows the permis- the largest and the smallest of the bore sible limit values of chamfer dimensions of radial Classification symbol diameters in a single radial plane (circularity). Cage symbol bearings. For thrust bearings, see the section on V means the difference between the largest accuracy of Thrust Bearings. Note that the series of dmp E and the smallest of the single plane mean bore Shell Type Needle Roller Bearings, Roller Bearings, (c) Example of "Bore diameter or roller set bore diameter + width" (d) Example of "Basic diameter" Cam Followers, Roller Followers, Combined Type diameters (cylindricity). Needle Roller Bearings, and Crossed Roller Bearings have special accuracy. For further details, see the F Supplemental Supplemental section on accuracy of each bearing series. Model number code Model number code NAX20 30 Z CF10 VB UU

Single bore diameter deviation ∆ds Model code Model code G Single plane mean bore diameter deviation ∆dmp Roller set bore diameter Basic diameter (Stud diameter) Single outside diameter deviation ∆ Deviation of boundary Ds Assembled bearing width Cage symbol dimensions ∆ Single plane mean outside diameter deviation Dmp H ∆ Shield symbol Shape of stud head Deviation of a single inner ring width Bs

Deviation of a single outer ring width ∆ Seal symbol Cs Accuracy of boundary dimensions Bore diameter variation in a single radial plane Vdsp I

Mean bore diameter variation Vdmp

Outside diameter variation in a single radial plane V Variation of boundary Dsp dimensions Mean outside diameter variation VDmp J

Accuracy of Inner ring width variation VBs bearings Outer ring width variation VCs K Radial runout of assembled bearing inner ring Kia

Assembled bearing inner ring face runout with raceway Sia

Rotational Inner ring reference face runout with bore Sd accuracy L Radial runout of assembled bearing outer ring Kea

Assembled bearing outer ring face runout with raceway Sea

Variation of outside surface generatrix inclination with outer ring reference face SD

Fig. 11 Accuracy of bearings M

A29 A30 Table 12 Tolerances for inner ring unit: μ m A d ∆ ∆ V V ∆ dmp ds dsp dmp K ia S d S ia(3) Bs VBs d Nominal bearing Single plane mean bore diameter deviation Single bore Bore diameter variation in a single radial plane Mean bore diameter Radial runout of Inner ring Assembled bearing Deviation of a single inner ring width Inner ring width variation Nominal bearing bore diameter diameter variation assembled bearing deviation reference face inner ring face bore diameter Diameter series 8, 9(1) Diameter series 0(2) inner ring runout with bore runout with raceway ClassClassClassClassClassClassClassClassClassClassClassClass Class Class Class ClassClass Class Class Class Class Class Class Class mm Class 0 Class 6 Class 5 Class 4 Class 4 Class 0 Class 6 Class 5 Class 4 mm B 0 6 5 4 0 6 5 4 0 6 5 4 0 6 5 4 5 4 5 4 0 6 5 4 Over Incl. HighLow HighLow High Low High Low High Low Max. Max. Max. Max. Max. Max.High Low HighLow High Low High Low Max. Over Incl. 2.5 10 0 - 8 0 - 7 0 - 5 0 - 4 0 - 4 10 9 5 4 8 7 4 3 6 5 3 2 10 6 4 2.5 7 3 7 3 0 - 120 0 - 120 0 - 40 0 - 40 15 15 5 2.5 2.5 10 10 18 0 - 8 0 - 7 0 - 5 0 - 4 0 - 4 10 9 5 4 8 7 4 3 6 5 3 2 10 7 4 2.5 7 3 7 3 0 - 120 0 - 120 0 - 80 0 - 80 20 20 5 2.5 10 18 18 30 0 - 10 0 - 8 0 - 6 0 - 5 0 - 5 13 10 6 5 10 8 5 4 8 6 3 2.5 13 8 4 3 8 4 8 4 0 - 120 0 - 120 0 - 120 0 - 120 20 20 5 2.5 18 30 C 30 50 0 - 12 0 - 10 0 - 8 0 - 6 0 - 6 15 13 8 6 12 10 6 5 9 8 4 3 15 10 5 4 8 4 8 4 0 - 120 0 - 120 0 - 120 0 - 120 20 20 5 3 30 50 50 80 0 - 15 0 - 12 0 - 9 0 - 7 0 - 7 19 15 9 7 19 15 7 5 11 9 5 3.5 20 10 5 4 8 5 8 5 0 - 150 0 - 150 0 - 150 0 - 150 25 25 6 4 50 80 80 120 0 - 20 0 - 15 0 - 10 0 - 8 0 - 8 25 19 10 8 25 19 8 6 15 11 5 4 25 13 6 5 9 5 9 5 0 - 200 0 - 200 0 - 200 0 - 200 25 25 7 4 80 120 120 180 0 - 25 0 - 18 0 - 13 0 - 10 0 - 10 31 23 13 10 31 23 10 8 19 14 7 5 30 18 8 6 10 6 10 7 0 - 250 0 - 250 0 - 250 0 - 250 30 30 8 5 120 180 180 250 0 - 30 0 - 22 0 - 15 0 - 12 0 - 12 38 28 15 12 38 28 12 9 23 17 8 6 40 20 10 8 11 7 13 8 0 - 300 0 - 300 0 - 300 0 - 300 30 30 10 6 180 250 250 315 0 - 35 0 - 25 0 - 18 44 31 18 44 31 14 26 19 9 50 25 13 13 15 0 - 350 0 - 350 0 - 350 35 35 13 250 315 D 315 400 0 - 40 0 - 30 0 - 23 50 38 23 50 38 18 30 23 12 60 30 15 15 20 0 - 400 0 - 400 0 - 400 40 40 15 315 400 400 500 0 - 45 0 - 35 56 44 56 44 34 26 65 35 0 - 450 0 - 450 50 45 400 500 500 630 0 - 50 0 - 40 63 50 63 50 38 30 70 40 0 - 500 0 - 500 60 50 500 630 630 800 0 - 75 80 0 - 750 70 630 800 800 1000 0 - 100 90 0 - 1000 80 800 1000 E 1000 1250 0 - 125 100 0 - 1250 100 1000 1250

1250 1600 0 - 160 120 0 - 1600 120 1250 1600 1600 2000 0 - 200 140 0 - 2000 140 1600 2000

Note(1) Applicable to all series except NAS series (2) Applicable to NAS series F (3) Applicable to NATA and NATB series

Table 13 Tolerances for outer ring unit: μ m

∆ ∆ (1) (4) ∆ G D Dmp Ds VDsp V Dmp Kea S D S ea Cs VCs D Nominal bearing Single plane mean outside diameter deviation Single out- Outside diameter variation in a single radial plane Mean outside Radial runout of Variation of outside Assembled Deviation of a single Outer ring width variation Nominal bearing outside diameter side diam- diameter variation assembled bearing surface generatrix bearing outer outer ring width outside diameter eter devia- Open bearing Bearing with seal or shield outer ring inclination with outer ring face runout tion ring reference face with raceway Diameter series 8, 9(2) Diameter series 0(3) Diameter series 0(3) ClassClassClassClassClassClassClassClass Class Class Class Class Class Class Class Class H mm Class 0 Class 6 Class 5 Class 4 Class 4 Class 6 Class 5 Class 4 Class 5 Class 4 Class 0, 6, 5, 4Class 0 Class 6 Class 5 Class 4 mm 0 6 5 4 0 6 5 4 0 6 5 4 0 6 5 4 Over Incl. HighLow HighLow High Low High Low High Low Max. Max. Max. Max. Max. Max. Max.High Low Max. Over Incl. 2.5 6 0 - 8 0 - 7 0 - 5 0 - 4 0 - 4 10 9 5 4 8 7 4 3 9 6 5 3 2 15 8 5 3 8 4 8 5 5 2.5 2.5 6 6 18 0 - 8 0 - 7 0 - 5 0 - 4 0 - 4 10 9 5 4 8 7 4 3 9 6 5 3 2 15 8 5 3 8 4 8 5 5 2.5 6 18 18 30 0 - 9 0 - 8 0 - 6 0 - 5 0 - 5 12 10 6 5 9 8 5 4 10 7 6 3 2.5 15 9 6 4 8 4 8 5 5 2.5 18 30 I 30 50 0 - 11 0 - 9 0 - 7 0 - 6 0 - 6 14 11 7 6 11 9 5 5 13 8 7 4 3 20 10 7 5 8 4 8 5 5 2.5 30 50 50 80 0 - 13 0 - 11 0 - 9 0 - 7 0 - 7 16 14 9 7 13 11 7 5 16 10 8 5 3.5 25 13 8 5 8 4 10 5 6 3 50 80 80 120 0 - 15 0 - 13 0 - 10 0 - 8 0 - 8 19 16 10 8 19 16 8 6 20 11 10 5 4 35 18 10 6 9 5 11 6 8 4 80 120 120 150 0 - 18 0 - 15 0 - 11 0 - 9 0 - 9 23 19 11 9 23 19 8 7 25 14 11 6 5 40 20 11 7 10 5 13 7 8 5 120 150 150 180 0 - 25 0 - 18 0 - 13 0 - 10 0 - 10 31 23 13 10 31 23 10 8 30 19 14 7 5 45 23 13 8 10 5 14 8 Same as the Same as the 8 5 150 180 J 180 250 0 - 30 0 - 20 0 - 15 0 - 11 0 - 11 38 25 15 11 38 25 11 8 23 15 8 6 50 25 15 10 11 7 15 10 tolerance tolerance 10 7 180 250 values of ∆ values of V 250 315 0 - 35 0 - 25 0 - 18 0 - 13 0 - 13 44 31 18 13 44 31 14 10 26 19 9 7 60 30 18 11 13 8 18 10 Bs Bs 11 7 250 315 315 400 0 - 40 0 - 28 0 - 20 0 - 15 0 - 15 50 35 20 15 50 35 15 11 30 21 10 8 70 35 20 13 13 10 20 13 for d of the for d of the 13 8 315 400 400 500 0 - 45 0 - 33 0 - 23 56 41 23 56 41 17 34 25 12 80 40 23 15 23 same bearing same bearing 15 400 500 500 630 0 - 50 0 - 38 0 - 28 63 48 28 63 48 21 38 29 14 100 50 25 18 25 18 500 630 K 630 800 0 - 75 0 - 45 0 - 35 94 56 35 94 56 26 55 34 18 120 60 30 20 30 20 630 800 800 1000 0 - 100 0 - 60 125 75 125 75 75 45 140 75 800 1000 1000 1250 0 - 125 160 1000 1250 1250 1600 0 - 160 190 1250 1600 1600 2000 0 - 200 220 1600 2000 2000 2500 0 - 250 250 2000 2500 L Note(1) Classes 0 and 6 are applicable to outer rings without stop rings. (2) Applicable to all series except NAS series (3) Applicable to NAS series (4) Applicable to NATA and NATB series M

1N=0.102kgf=0.2248lbs. A31 1mm=0.03937inch A32 Table 14 Tolerances for smallest single roller set Table 15 Permissible limit values for chamfer 1 Methods of Measurement A bore diameter F ws min( ) unit: μm dimensions of radial bearings unit: mm F ∆ d r w Fws min r s min s max Measurement of Needle Roller Bearings is Nominal roller set bore diameter Deviation of smallest single roller set bore diameter Smallest Nominal bore diameter Largest permissible single chamfer dimension based on JIS B 1515:1988 (Methods of Measurement mm permissible single for Roller Bearings). Tables 16 and 17 show some Over Incl. High Low chamfer dimension Over Incl. Radial direction Axial direction B examples of the methods. 3 6 ＋ 18 ＋ 10 2 2 0.1 ─ ─ 0.55（ ） 0.55（ ） Special methods are used to measure Shell Type 6 10 ＋ 22 ＋ 13 0.15 ─ ─ 0.6 （2） 0.6 10 18 Needle Roller Bearings. Therefore, refer to the sec- ＋ 27 ＋ 16 0.2 ─ ─ 0.7 （2） 0.8 18 30 33 20 tion on accuracy for these bearings on page B3. ＋ ＋ ─ 40 0.8 （2） 1 0.3 C 30 50 ＋ 41 ＋ 25 40 ─ 0.8 1 50 80 49 30 ＋ ＋ 0.4（1） ─ ─ 0.8 1.2 Table 16 Measurement methods of accuracy of boundary dimensions 80 120 ＋ 58 ＋ 36 ─ 40 1.1 （2） 2 120 180 0.6 ＋ 68 ＋ 43 40 ─ 1.3 2 Measurement methods Accuracy and definitions 180 250 ＋ 79 ＋ 50 ─ 50 1.5 3 D 250 315 ＋ 88 ＋ 56 1 50 ─ 1.9 3 d sp max＋ d sp min 315 400 ＋ 98 ＋ 62 d mp ＝ ─ 120 2 3.5 Bore In principle, measurements of dimensions 2 400 500 ＋ 108 ＋ 68 1.1 are carried out using a two-point measur- d mp 120 ─ 2.5 4 diameter d sp max ：Maximum value of bore diameter (d s) 1 Single plane mean Note( ) This is the diameter of the cylinder used instead of the ─ 120 2.3 4 ing instrument for various radial planes. obtained for a single radial plane inner ring, where the radial clearance becomes 0 at least 1.5 bore diameter d ：Minimum value of bore diameter (d ) E in one radial direction. 120 ─ 3 5 sp min s ─ 80 3 4.5 obtained for a single radial plane 2 80 220 3.5 5 ∆ dmp ∆ ＝ d － d 220 ─ 3.8 6 Single plane mean bore dmp mp ─ 280 4 6.5 d ：Nominal bore diameter 2.1 diameter deviation 280 ─ 4.5 7 F V dsp 100 3.8 6 ─ Bore diameter variation V dsp ＝ d sp max － d sp min （1） 2.5 100 280 4.5 6 in a single radial plane 280 ─ 5 7 V ＝ d － d ─ 280 5 8 dmp mp max mp min 3 d ：Maximum value of single plane mean bore G 280 ─ 5.5 8 V dmp mp max Mean bore diameter diameters d for various radial planes 4 ─ ─ 6.5 9 mp variation d ：Minimum value of single plane mean bore 5 ─ ─ 8 10 This does not apply to the regions within a mp min diameters d mp for various radial planes 6 ─ ─ 10 13 range of 1.2 times the largest permissible single chamfer dimension from both side- ∆ 1 ds Note( )Not specified in JIS. ∆ ds ＝ d s － d H (2) The numeric value differs from JIS. surfaces of the inner ring. Single bore diameter d s ：Any measured bore diameter obtained in any radial plane Remark Although the exact shape of the chamfer is not specified, deviation its profile in the axial plane must not extend beyond the D ＋ D imaginary circular arc of radius rs min which is tangential D sp max sp min to the inner ring side surface and bearing bore surface or Outside In principle, measurements of dimensions mp ＝ D 2 to the outer ring side surface and bearing outside sur- diameter are carried out using a two-point measur- mp D ：Maximum value of outside diameter (D ) I face. (See Fig. 12.) Single plane mean sp max s ing instrument for various radial planes. obtained for a single radial plane outside diameter D sp min ：Minimum value of outside diameter (D s) obtained for a single radial plane ∆ Dmp ∆ ＝ D － D J Single plane mean outside Dmp mp D ：Nominal outside diameter diameter deviation

V Dsp Outside diameter variation V Dsp ＝ D sp max － D sp min in a single radial plane K

V Dmp ＝ D mp max － D mp min V Dmp D mp max ：Maximum value of single plane mean outside Mean outside diameters D mp for various radial planes This does not apply to the regions within a diameter variation D mp min ：Minimum value of single plane mean outside L range of 1.2 times the largest permissible diameters D mp for various radial planes

single chamfer dimension from both side- ∆ Ds ∆ Ds ＝ D s － D surfaces of the outer ring. Single outside Fig. 12 Permissible values for chamfer dimensions D s ：Any measured outside diameter obtained in any radial plane diameter deviation M

1N=0.102kgf=0.2248lbs. A33 1mm=0.03937inch A34 Table 17 Measurement methods for rotational accuracy A

Measurement methods Accuracy and definitions Accuracy Measurement methods

In principle, this is measured using a master gauge. The inner ring reference face runout with bore, in principle, is measured S d Roller set The master gauge is fixed on the base with its side using a tapered arbor. ∆ ＝(d δ )－F Inner ring B bore diameter surface downward, and the outer ring with needle ∆ Fws G ＋ 1m w The bearing is correctly fitted to the arbor, which is held by both centers Fws reference face so that it can rotate smoothly without play. An indicator probe is applied rollers is fitted onto the gauge. An indicator probe is Deviation of a single dG ：Outside diameter of master gauge axially to the approximate middle of the width of the flat part of the inner applied radially to the approximate middle of the out- roller set bore diam- runout with δ1m ：Arithmetical mean value of outer ring movement ring reference side-surface. The tapered arbor together with the bearing side surface of the outer ring, and a measuring load eter bore is applied in that direction inward and outward alter- Fw ：Nominal dimension of roller set bore diameter is turned fully once to obtain the runout, which is the difference between C nately to obtain the amount of outer ring movement. the maximum and minimum readings of the indicator. Measurements are taken at various angular posi- The outer ring reference side-surface is placed on a flat base, and the inner ring is S tions by turning the outer ring. D left free. Two stoppers are applied to the outside cylindrical surface of the outer Variation of ring at a distance of 1.2 times the maximum permissible chamfer dimension (r s ∆ outside surface ) from the base. Just above one of the stoppers, an indicator probe is applied D Fws min ∆ Fws min ＝(dG ＋δ1min)－ Fw max Deviation of small- generatrix radially to the outside cylindrical surface of the outer ring at a distance of 1.2 times the maximum permissible chamfer dimension (r ) from the upper side-sur- est single roller set δ1min ：Minimum value of outer ring movement inclination s max face. The outer ring is turned fully once along the stoppers to obtain the Variation bore diameter with outer ring which is the difference between the maximum and the minimum readings of the reference face indicator. E The radial runout of the inner ring is measured by holding the tapered The inner ring width is measured between K ia ∆ arbor, to which the bearing is correctly fitted, horizontally by both centers the base and the indicator probe perpen- Bs ＝ B s － B Inner ring ∆ Bs Radial runout so that it can rotate smoothly without play. An indicator probe is applied dicular to the base. width Deviation of a single of assembled radially downward to the approximate middle of the width of the outside- B s ：Single inner ring width F inner ring width surface of the outer ring. The inner ring, together with the tapered arbor, B ：Nominal inner ring width bearing inner ring is turned fully once to obtain the radial runout, which is the difference between the maximum and the minimum readings of the indicator. (The V Bs ＝ B s max － B s min outer ring is not rotated.) V Bs The radial runout of the outer ring is measured by holding the tapered G K ea Inner ring width variation B s max ：Maximum value of single inner ring width arbor, to which the bearing is correctly fitted, horizontally by both centers B s min ：Minimum value of single inner ring width Radial runout so that it can rotate smoothly without play. An indicator probe is applied of assembled radially downward to the approximate middle of the width of the outside- The outer ring width is measured between ∆ ＝ C － C bearing outer surface of the outer ring. The outer ring is turned fully once to obtain the Outer ring the base and the indicator probe perpen- ∆ Cs s H Cs ring radial runout, which is the difference between the maximum and the mini- width dicular to the base. Deviation of a single C ：Single outer ring width mum readings of the indicator. (The inner ring is not rotated.) outer ring width s C ：Nominal outer ring width In the case of needle roller bearings without inner ring, the measurement is carried out by using a cylindrical arbor instead of the inner ring.

V Cs ＝ C s max － C s min S ia The axial runout of the inner ring is measured by placing the outer ring on I a flat base with the center axis of the bearing vertical. An indicator probe V Cs Assembled is applied axially to the approximate middle of the flat part of the inner ring Outer ring width variation C s max ：Maximum value of single outer ring width bearing inner reference side-surface. The specified measuring weight is applied to the C s min ：Minimum value of single outer ring width ring face runout inner ring reference side-surface in the direction of the center axis. The J In principle, the height is measured between with raceway inner ring is turned fully once to obtain the runout, which is the difference Bearing the base plane on which the back surface of between the maximum and the minimum readings of the indicator. the outer ring is placed and the disk master height The axial runout of the outer ring is measured by placing the inner ring on placed on the back surface of the inner ring. ∆ Ts ＝ T s － T S ea ∆ Ts the flat base with the center axis of the bearing vertical. An indicator Deviation of the Assembled probe is applied axially to the approximate middle of the flat part of the K T ：Actual bearing height actual bearing height s bearing outer outer ring reference side-surface. The specified measuring weight is T ：Nominal bearing height ring face runout applied to the outer ring reference side-surface in the direction of the cen- ter axis. The outer ring is turned fully once to obtain the runout, which is with raceway the difference between the maximum and the minimum readings of the indicator. L

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1N=0.102kgf=0.2248lbs. A35 1mm=0.03937inch A36 ∆ ∆ ∆ 1 Table 18 shows the radial internal clearances of Selection of clearance C ＝ F ＋ E ………………………………(24) A Clearance Needle Roller Bearings with Inner Ring based on JIS B 1520:1995 (Radial internal clearances of rolling bear- where, ∆ Amount of reduction of the radial The clearances between the bearing rings and rolling Radial clearances of needle roller bearings change C ： ings). The radial internal clearances are classified clearance, mm elements are known as bearing clearances. When according to bearing fit, temperature difference into C2, CN, C3, C4, and C5, with clearances increas- ∆ Amount of expansion of the out- either the inner or outer ring is fixed and a specified between bearing rings and rolling elements, loads, F ： ing in this order. CN is used under normal operating side diameter of inner ring, mm B measuring load is applied to the free bearing ring etc., and these factors greatly influence bearing life, conditions. When a smaller range in radial internal ∆ Amount of shrinkage of the bore inward and outward alternately in the radial direction, accuracy, noise, generation of heat, etc. If radial E ： clearance than the values shown in Table 18 is diameter of outer ring, mm the displacement of the free bearing is referred to as clearances are too large, noise and vibration will required, please consult . the radial internal clearance. The amount of measur- increase, and if they are too small, abnormally great 1 Amount of expansion of the outside diameter of inner ring ing load in this case is extremely small, and its values forces are exerted on the contact areas between C 2 In the case of Shell Type Needle Roller Bearings, raceways and rolling elements, resulting in abnormal- are specified in JIS B 1515:1988 (Methods of the correct dimensional accuracy is achieved only With solid shaft Measurement for Rolling Bearings). ly high heat generation and a decrease in bearing life. ・ after the bearings are press-fitted into the specified Therefore, in the ideal case, the clearance provided d housing bore. Therefore, the clearances shown in ∆ ＝ ∆ ………………………………(25) before mounting should be such that it will become F de F D Table 18 are not applicable. See page B5. zero or slightly larger when the bearing has reached ・ With hollow shaft steady-state operation and the temperature has 3 For the radial internal clearances of Cam Followers, become constant (saturation temperature). However, 2 ∆ ∆ d 1 －(d i/d) Roller Followers and Crossed Roller Bearings, see the F ＝ de 2 2 ……(26) it is difficult to achieve this ideal state for all bearings. F 1 －(d/F) (d i/d) relevant section for each bearing. Under general operating conditions, bearings with CN E where, ∆ ： Effective interference of inner ring, mm clearance are most widely used, and are manufac- de d ： Bore diameter of inner ring, mm tured to provide satisfactory performance when fitted F ： Outside diameter of inner ring, mm according to Tables 21 and 22. d ： Bore diameter of hollow shaft, mm When radial internal clearances other than CN are i F used, refer to Table 19. 2 Amount of shrinkage of the bore diameter of outer ring

Table 18 Radial internal clearances of Needle Roller Bearings unit: μm ・ With steel housing（D ＝∞） d Classification of clearances Table 19 Examples of selecting radial internal 0 Nominal bore diameter clearances other than CN clearance E G C2 CN C3 C4 C5 ∆ ＝∆ ………………………………(27) mm E De D Over Incl. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Operating conditions Selection of clearance ・ With steel housing（D 0 ≠∞） ─ 10 0 25 20 45 35 60 50 75 ─ ─ When heavy loads and shock loads are 2 10 24 0 25 20 45 35 60 50 75 65 90 ∆ ∆ E 1 －(D/D0) H applied, and amount of interference is great. E ＝ De 2 2 ……(28) 24 30 0 25 20 45 35 60 50 75 70 95 D 1 －(E/D) (D/D 0) 30 40 5 30 25 50 45 70 60 85 80 105 When directionally indeterminate loads are applied, where, ∆ De ： Effective interference of outer ring, mm 40 50 5 35 30 60 50 80 70 100 95 125 and a tight fit is required for both inner and outer rings. C3 or larger clearance D ： Outside diameter of outer ring, mm 50 65 10 40 40 70 60 90 80 110 110 140 When temperature of inner ring is much E ： Bore diameter of outer ring, mm 65 80 10 45 40 75 65 100 90 125 130 165 higher than that of outer ring. I D 0 ： Outside diameter of housing, mm 80 100 15 50 50 85 75 110 105 140 155 190 When shaft deflection and/or mounting 100 120 15 55 50 90 85 125 125 165 180 220 error to the housing are great. Reduction of radial clearances due to 120 140 15 60 60 105 100 145 145 190 200 245 temperature differences between inner 140 160 20 70 70 120 115 165 165 215 225 275 When less noise and vibration are required. J When a loose fit is required for both inner and outer rings. C2 or smaller clearance and outer rings 160 180 25 75 75 125 120 170 170 220 250 300 When preload is required. 180 200 35 90 90 145 140 195 195 250 275 330 Frictional heat generated by rotation is dissipated 200 225 45 105 105 165 160 220 220 280 305 365 through the shafts and housings as well as through oil 225 250 45 110 110 175 170 235 235 300 330 395 Reduction of radial clearances by fit and air. Under general operating conditions, heat dis- K 250 280 55 125 125 195 190 260 260 330 370 440 sipation is larger on the housing side compared with 280 315 55 130 130 205 200 275 275 350 410 485 When the inner or outer rings are interference fitted that on the shaft side, and the temperature of the 315 355 65 145 145 225 225 305 305 385 455 535 onto shafts and into housings, respectively, they outer ring is usually lower than that of the inner ring. 355 400 100 190 190 280 280 370 370 460 510 600 expand or shrink due to elastic deformation. As the During operation, the temperature of the rolling ele- 400 450 110 210 210 310 310 410 410 510 565 665 L result, the radial clearances are reduced. These ments is the highest, followed by that of the inner ring 450 500 110 220 220 330 330 440 440 550 625 735 reduced radial clearances are called residual (inter- and that of the outer ring. The amount of thermal Remark For bearings with CN clearance, no symbol is attached to the identification number. In the case of bearings with C2, C3, C4 and C5 expansion, therefore, varies, and the radial clearances clearances, these symbols are attached to the identification number. nal) clearances. Example NA 4905 C2 The amount of reduction is obtained by the following are reduced. This reduced radial clearance is called equation, and it is generally 70 to 90% of the interfer- the effective (internal) clearance, and the amount of M ence amount. reduction is obtained by the following equation:

1N=0.102kgf=0.2248lbs. A37 1mm=0.03937inch A38 ∆ α∆ as ∆ , the temperature difference between the inner δ＝ t E …………………………………(29) Conditions for determination of fit T A Fit ring and the shaft can be estimated to be (0.1 ～ 0.15) ∆ ∆ . Accordingly, the amount of reduction of the inner where, δ ： Reduction of radial clearance, mm Purpose of fit When determining a suitable fit for a bearing, it is nec- T α ：Coefficient of linear expansion for essary to consider various conditions such as nature ring interference is obtained by the following equation.

bearing steel and magnitude of the load, temperature, required -3 To achieve the best performance of needle roller ∆ dT＝ (0.1～0.15) ∆ T αd≒0.0015 ∆ T d×10 …(32) ≒ 12.5 × 10-6 1/。 C rotational accuracy, material/finish grade/thickness of B bearings, it is important that the bearing rings are cor- ∆ t ：Temperature difference between the the shaft and housing, ease of mounting and dis- where, ∆ ：Reduction amount of inner ring rectly fitted onto the shaft and into the housing. dT outer ring and the inner ring plus rolling mounting, etc. interference due to temperature The purpose of fit is to provide the appropriate elements considered as one unit,。 C difference, amount of interference required between the inner mm E ： Bore diameter of outer ring, mm 1 Nature of load and fit ∆ ring and the shaft or between the outer ring and the T ：Temperature difference between C Basically, the appropriate fit depends on whether the housing, to prevent harmful mutual slippage. the inside of the bearing and the The temperature difference ∆ t is considered to be 5 load direction is rotational or stationary in relation to If the interference is insufficient, it will cause a harmful outside of the housing,。 C ～10。C under normal operating conditions and 15 ～ the inner and outer rings. relative displacement, known as creep, between the α ：Coefficient of linear expansion 20。 C at high rotational speeds. Therefore, when the The relationship between the nature of radial loads fitted surfaces in the circumferential direction. This for bearing steel D temperature difference is great, a correspondingly and the fit is, in general, based on Table 20. may lead to abnormal wear of fitted surfaces, intru- -6 larger radial internal clearance must be selected. ≒ 12.5 × 10 1/。 C sion of wear particles into the bearing, generation of 2 Load amount and interference d ：Bore diameter of inner ring, mm abnormal heat, vibration, etc. Therefore, a suitable fit The greater the load, the larger the interference must must be selected. be. 4 Shaft finish grade and interference E When selecting an interference between the inner ring Since peaks of surface roughness of the fitted surface Table 20 Nature of radial load and fit and the shaft, it is necessary to estimate the reduction are crushed down when fitting the bearing, the effec- tive interference becomes smaller than the apparent Fit of interference due to the radial load. The amount of Nature of the load reduction of interference is obtained by the following interference obtained by measurements, and it is gen- F Rotating conditions Inner ring Outer ring equations. erally obtained by the following equations. ・ For ground shaft

Inner ring : Rotating ・ When F r ≦ 0.2C 0 d Outer ring : Stationary ∆ de ＝ ∆ df …………………………(33) d ＋ 2 Load direction : Fixed d -3 G ∆ dF ＝ 0.08 F r × 10 ………………(30) √B ・ For machined shaft Rotating load on inner ring Interference fit Clearance fit Stationary load on outer ring ・ When F r>0.2C 0 d ∆ de ＝ ∆ df …………………………(34) Inner ring : Stationary d ＋ 3 ∆ F r -3 H Outer ring : Rotating dF ＝ 0.02 × 10 ……………………(31) B where, ∆ Effective interference of inner Load direction : Rotating with outer ring de ： ring, mm where, F r ： Radial load applied to bearing, N d Bore diameter of inner ring, mm C0 ： Basic static load rating, N ： ∆ Apparent interference, mm I ∆ dF ：Amount of reduction of inner df ： Inner ring : Stationary ring interference, mm Outer ring : Rotating d ： Bore diameter of inner ring, mm 5 Minimum interference and maximum interference Load direction : Fixed When the load direction is rotating in relation to the B ： Width of inner ring, mm inner ring, the inner ring is fitted with interference to Rotating load on outer ring Clearance fit Interference fit J the shaft. Stationary load on inner ring 3 Temperature conditions and change of interference For solid ground steel shafts, the minimum interfer- Inner ring : Rotating The interference of fitted surfaces is also influenced ence (required apparent interference) ∆ df is Outer ring : Stationary by the temperature difference between the bearing expressed by the following equation which is deduced Load direction : Rotating with inner ring and the shaft and housing. For example, when steam from equations (30) or (31), (32) and (33). K is flowing through a hollow shaft, or when the housing is made of light metal, it is necessary to take into con- d＋ 2 ∆ ≧ (∆ ＋ 0.0015 ∆ d × 10 -3) …(35) The load direction is not sideration the differences in temperature, the coeffi- df d dF T fixed, including cases where Inner ring : Rotating or stationary cient of linear expansion and other such factors. Directionally indeterminate load the load direction is fluctuat- Outer ring : Rotating or stationary Interference fit Interference fit Usually, the interference of the inner ring decreases It is desired that the maximum interference should be L ing or there is an unbal- Load direction : Not fixed as the bearing temperature increases during opera- less than 1/1000 of the shaft diameter. In the case of anced load. tion. If the temperature difference between the inside the outer ring, the effective interference varies accord- of the bearing and the outside of the housing is taken ing to the housing material, thickness, shape, etc., so it is determined empirically. M

1N=0.102kgf=0.2248lbs. A39 1mm=0.03937inch A40 Selection of fit Table 22 Fit between needle roller bearings with inner ring and shafts A Shaft dia. mm Tolerance class Application examples When selecting a suitable fit, in addition to the various Operating conditions 1 Over Incl. of shaft（ ） (Reference) conditions mentioned above, it is necessary to draw on experience and practical results. Light load, normal load, low or g6 Tables 21 and 22 show the most general fit data. medium rotating speed Wheels on dead axles B When a thin housing or a hollow shaft is used, the Stationary load Control lever gears Heavy load, medium rotating speed All shaft diameters h6 interference is made larger than an ordinary fit. on inner ring Rope sheaves The fit between needle roller bearings without inner Especially smooth operation and Tension pulleys ring and shafts is based on Table 23. h5 C accuracy are required. For the fit between Shell Type Needle Roller Bearings and housing bores, see page B5. － 50 j5 Electric appliances, Precision machinery 100 k5 For the fit between inner rings for Shell Type Needle Light load 50 Machine tools, Pumps 100 200 m6（2） Roller Bearings and shafts, see Table 22. Blowers, Transportation vehicles Rotating load 200 － n6（3） D on inner ring or k5 4 Directionally － 50 （ ） General bearing applications m5，m6 2 indeterminate Normal load 50 150 （ ） Pumps, Transmission gearboxes, Table 21 Fit between needle roller bearings and housing bores (Not applicable to Shell Type Needle Roller Bearings) 150 200 n6（3） load Wood working machinery, Internal combustion engines 200 p6（3） Tolerance class of － E Operating conditions Application examples (Reference) housing bore（1） Heavy load － 150 n6（3） Industrial vehicles, Construction machinery Shock load 150 － p6（3） Crushers Heavy load on thin housing, large P7（2） Flywheels 1 shock load Notes( ) This table applies to solid steel shafts. (2) It is necessary to examine the reduction of radial internal clearances caused by the expansion of inner rings after mounting. 3 Rotating load on ( )It is necessary to use bearings with radial internal clearances greater than CN clearance. F Heavy load, normal load N7（2） Wheel bosses, transmission gears (4) For NATA and NATB, do not use a tighter fit than k5. outer ring

Light load, fluctuating load M7 Pulleys, tension pulleys Table 23 Tolerance class of shafts assembled with needle roller bearings without inner ring Radial internal clearance Fw G Large shock load M7 Eccentric wheels, pumps Nominal roller set bore diameter mm Smaller than CN clearance CN clearance Larger than CN clearance Directionally indeterminate Heavy load, normal load Compressors K7 Over Incl. Tolerance class of shaft（1） load H － 65 k5 h5 g6 Normal load, light load J7 Crankshafts, compressors 65 80 k5 h5 f6 80 160 k5 g5 f6 Shock load, heavy load J7 General bearing applications, gear shafts 160 180 k5 g5 e6 180 200 j5 g5 e6 I Stationary load Normal load, light load H7 General bearing applications 200 250 j5 f6 e6 on outer ring 250 315 h5 f6 e6 With heat conduction through shaft G7 Paper dryers 315 － g5 f6 d6 Note(1) When the housing bore fit is tighter than K7, the shaft diameter is made smaller by considering shrinkage of roller set bore diameter J Light load, normal load, requirements of high-precision after mounting. K6 Main spindles of machine tools rotation and high rigidity

Notes(1) This table applies to steel or cast iron housings. For lighter metal, a tighter fit should be selected. For split housings, do not use a fit tighter than J7. (2) Care should be taken so that the radial internal clearance is not too small. K Remark Light load, normal load and heavy load represent P ≦ 0.06C, 0.06C

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1N=0.102kgf=0.2248lbs. A41 1mm=0.03937inch A42 Table 24 Fit values for radial bearings (JIS Class 0) (Fit with housing bore) unit: μｍ Design of Shaft and Housing Inclination of shaft A D ∆ Dmp G7 H7 J7 K6 K7 M7 N7 P7 Shafts and outer rings may have some inclination Nominal outside Single plane mean Accuracy and roughness of shaft and housing diameter outside diameter between them due to deflection of the shaft, machin- Housing Housing Housing Housing Housing Housing Housing Housing mm deviation ing accuracy of shafts and housings, errors in mount- Bearing Bearing Bearing Bearing Bearing Bearing Bearing Bearing Accuracy and roughness of fitting surface ing, etc. B Over Incl. High Low In this case, the use of two or more bearings in tan- 3 6 0 - 8 - 24 ～ - 4 - 20 ～ 0 -14 ～ 6 -10 ～ 6 -11 ～ 9 -8～ 12 -4～ 16 0 ～ 20 Since the bearing rings of needle roller bearings are dem arrangement on a single shaft should be avoid- 6 10 0 - 8 - 28 ～ - 5 - 23 ～ 0 -16 ～ 7 -10 ～ 7 -13 ～ 10 -8～ 15 -4～ 19 1 ～ 24 thin, their performance is easily affected by poor ed. Instead, a bearing with large load ratings should 10 18 0 - 8 - 32 ～ - 6 - 26 ～ 0 -18 ～ 8 -10 ～ 9 -14 ～ 12 -8～ 18 -3～ 23 3 ～ 29 accuracy of shafts or housings. Under general oper- be used. 18 30 0 - 9 C - 37 ～ - 7 - 30 ～ 0 -21 ～ 9 -11 ～ 11 -15 ～ 15 -9～ 21 -2～ 28 5 ～ 35 ating conditions, the fitting surfaces of shafts and It is recommended that inclination of shafts be less 30 50 0 -11 - 45 ～ - 9 - 36 ～ 0 -25 ～ 11 -14 ～ 13 -18 ～ 18 -11 ～ 25 -3～ 33 6 ～ 42 housings can be finished by lathe turning. However, than 1/1000. 50 80 0 -13 - 53 ～ -10 - 43 ～ 0 -31 ～ 12 -17 ～ 15 -22 ～ 21 -13 ～ 30 -4～ 39 8 ～ 51 when the load is great and high accuracy and low 80 120 0 -15 - 62 ～ -12 - 50 ～ 0 -37 ～ 13 -19 ～ 18 -25 ～ 25 -15 ～ 35 -5～ 45 9 ～ 59 noise are required, a grinding finish is required. Table 27 Tolerance class IT values for basic 120 150 0 -18 - 72 ～ -14 - 58 ～ 0 -44 ～ 14 -22 ～ 21 -30 ～ 28 -18 ～ 40 -6～ 52 10 ～ 68 Table 26 shows the accuracy and roughness of fitting dimensions D 150 180 0 -25 - 79 ～ -14 - 65 ～ 0 -51 ～ 14 -29 ～ 21 -37 ～ 28 -25 ～ 40 -13～ 52 3 ～ 68 surfaces for general use. Basic dimension Tolerance class 180 250 0 -30 - 91 ～ -15 - 76 ～ 0 -60 ～ 16 -35 ～ 24 -43 ～ 33 -30 ～ 46 -16～ 60 3 ～ 79 mm IT5 IT6 IT7 250 315 0 -35 -104 ～ -17 - 87 ～ 0 -71 ～ 16 -40 ～ 27 -51 ～ 36 -35 ～ 52 -21～ 66 1 ～ 88 Accuracy and roughness of raceway surface 315 400 0 -40 -115 ～ -18 - 97 ～ 0 -79 ～ 18 -47 ～ 29 -57 ～ 40 -40 ～ 57 -24～ 73 1 ～ 98 Over Incl. Tolerance μｍ E 400 500 0 -45 -128 ～ -20 -108 ～ 0 -88 ～ 20 -53 ～ 32 -63 ～ 45 -45 ～ 63 -28～ 80 0 ～ 108 In case of needle roller bearings unlike other bear- － 3 4 6 10 Remark The negative value denotes a clearance and the positive value denotes an interference. ings, mating surfaces such as shaft and housing bore 3 6 5 8 12 surfaces can be used directly as the raceway sur- 6 10 6 9 15 faces. For such use, accuracy and roughness of the 10 18 8 11 18 Table 25 Fit values for radial bearings (JIS Class 0) (Fit with shaft) unit: μｍ raceway surfaces are important because they will 18 30 9 13 21 F ∆ g6 h5 h6 j5 k5 m5 m6 n6 p6 d dmp influence bearing life, noise and accuracy. 30 50 11 16 25 Nominal bore Single plane mean In general, accuracy and roughness of raceway sur- 50 80 13 19 30 diameter bore diameter 80 120 15 22 35

Bearing Bearing Bearing Bearing Bearing Bearing Bearing Bearing Bearing faces are based on Table 26. mm deviation 120 180 18 25 40 G Shaft Shaft Shaft Shaft Shaft Shaft Shaft Shaft Shaft Over Incl. High Low 180 250 20 29 46 315 23 32 52 3 6 0 -8 -12 ～ 4 -5～ 8 -8～ 8 -2～ 11 1 ～ 14 4 ～ 17 4 ～ 20 8 ～ 24 12 ～ 28 250 400 25 36 57 6 10 0 -8 -14 ～ 3 -6～ 8 -9～ 8 -2～ 12 1 ～ 15 6 ～ 20 6 ～ 23 10 ～ 27 15 ～ 32 315 500 27 40 63 10 18 0 -8 -17 ～ 2 -8～ 8 -11 ～ 8 -3～ 13 1 ～ 17 7 ～ 23 7 ～ 26 12 ～ 31 18 ～ 37 400 630 30 44 70 H 18 30 0 -10 -20 ～ 3 -9～ 10 -13 ～ 10 -4～ 15 2 ～ 21 8 ～ 27 8 ～ 31 15 ～ 38 22 ～ 45 500 30 50 0 -12 -25 ～ 3 -11 ～ 12 -16 ～ 12 -5～ 18 2 ～ 25 9 ～ 32 9 ～ 37 17 ～ 45 26 ～ 54 50 80 0 -15 -29 ～ 5 -13 ～ 15 -19 ～ 15 -7～ 21 2 ～ 30 11 ～ 39 11 ～ 45 20 ～ 54 32 ～ 66 80 120 0 -20 -34 ～ 8 -15 ～ 20 -22 ～ 20 -9～ 26 3 ～ 38 13 ～ 48 13 ～ 55 23 ～ 65 37 ～ 79 Table 26 Specifications of shafts and housings for radial needle roller bearings 120 140 I Shaft Housing bore 140 160 0 -25 -39 ～ 11 -18 ～ 25 -25 ～ 25 -11 ～ 32 3 ～ 46 15 ～ 58 15 ～ 65 27 ～ 77 43 ～ 93 Item 160 180 Fitting surface Raceway surface Fitting surface Raceway surface 180 200 0.3 × IT6（1） 0.3 × IT6（1） 0.3 × IT7（1） 0.3 × IT7（1） 200 225 0 -30 -44 ～ 15 -20 ～ 30 -29 ～ 30 -13 ～ 37 4 ～ 54 17 ～ 67 17 ～ 76 31 ～ 90 50 ～ 109 Circularity or or or or 1 1 1 1 J 225 250 0.3 × IT5（ ） 0.3 × IT5（ ） 0.3 × IT6（ ） 0.3 × IT6（ ） 250 280 0.5 × IT6（2） 0.3 × IT6（1） 0.5 × IT7（2） 0.3 × IT7（1） 0 -35 -49 ～ 18 -23 ～ 35 -32 ～ 35 -16 ～ 42 4 ～ 62 20 ～ 78 20 ～ 87 34 ～ 101 56 ～ 123 Cylindricity 280 315 or or or or 0.5 × IT5（2） 0.3 × IT5（1） 0.5 × IT6（2） 0.3 × IT6（1） 315 355 0 -40 -54 22 -25 40 -36 40 -18 47 4 69 21 86 21 97 37 113 62 138 ～～～～～～3 3 K 355 400 Surface roughness μ mRa 0.8 0.2（ ） 1.6 0.2（ ） 400 450 （μ mRy） (3.2) (0.8) (6.3) (0.8) 0 -45 -60 ～ 25 -27 ～ 45 -40 ～ 45 -20 ～ 52 5 ～ 77 23 ～ 95 23 ～ 108 40 ～ 125 68 ～ 153 450 500 Remark The negative value denotes a clearance and the positive value denotes an interference. Hardness － 58 ～ 64HRC（4） － 58 ～ 64HRC（4） L

Notes(1) 30% or less of the dimensional tolerance for shafts or housing bores is recommended. (2) 50% or less of the dimensional tolerance for shafts or housing bores is recommended. 3 ( ) When required accuracy is not critical, a surface roughness within 0.8 μ mRa (3.2 μ mRy ) is allowable. (4) An appropriate thickness of the hardened layer is required. M

1N=0.102kgf=0.2248lbs. A43 1mm=0.03937inch A44 Raceway materials and heat treatment Dimensions related to mounting of bearings Table 28 Largest permissible single corner radius entry of harmful foreign substances, such as dirt, dust A of shafts and housings ras max and water. For this reason, sealing devices must When using shafts and housings as raceways, the fol- The dimensions of shaft and housing related to unit: mm always work effectively to seal and prevent against lowing materials are generally used. mounting of the needle roller bearings are shown in r s min r as max dust penetration under all operating conditions. Also, High-carbon chromium bearing steel the table of dimensions for each bearing. (See Fig. Smallest permissible Largest permissible single when selecting a suitable sealing method, it is neces- single chamfer corner radius of shafts and B SUJ2 JIS G 4805 13.) sary to consider such factors as the type of lubricant, dimension housings peripheral speed of the seal, operating temperature, Carburizing steel SCM415 ～ 421 JIS G 4105 The minimum value of the shaft shoulder diameter d a which receives the inner ring, and the maximum value 0.1 0.1 shaft eccentricity, seal friction, etc. as well as ease of Carburizing steel SNCM 220 JIS G 4103 0.15 0.15 of the housing shoulder diameter D which receives assembly and disassembly. Carburizing steel SCr 420 JIS G 4104 a 0.2 0.2 the outer ring, represent the effective shoulder diame- Sealing methods are of the non-contact and contact C Carburizing steel SNC 415、815 JIS G 4102 0.3 0.3 ters (excluding the chamfered part) which make prop- types, and it is necessary to select the appropriate Carburizing steel S 15 CK JIS G 4051 0.4 0.4 er contact with the side faces of the inner and outer type depending on the application. In addition, S50C and S55C (JIS G 4051) can be 0.6 0.6 rings respectively. used after through hardening or induction hardening. 1 1 Also, the maximum value of the shaft shoulder (or 1.1 1 Non-contact type sealing method The hardened layer produced by tempering at +160 D inner ring retaining piece) diameter d is the dimen- 1.5 1.5 ～+180。 C after hardening must have a fine uniform a sion related to the ease of mounting/dismounting of 2 2 There are many methods of non-contact type sealing, martensite microstructure. the shaft and inner ring to/from the housing and outer 2.1 2 including the use of oil grooves, flingers and When hardening the raceway surface by case hard- ring. 2.5 2 labyrinths, which utilize the centrifugal force and nar- ening or induction hardening, a surface hardness of The largest permissible single corner radius r of 3 2.5 row gaps. E 58 ～ 64HRC and an appropriate thickness of the as max the shaft and housing must be smaller than the small- 4 3 Since they do not make direct contact with the shaft hardened layer must be ensured. The minimum est permissible single chamfer dimension r of the 5 4 or housing, it is unnecessary to consider friction and effective thickness of the hardened layer after heat s min bearing so that the side surface of the bearing can wear, and the non-contact sealing method is suitable treatment and grinding is defined as the distance from make proper contact with the shoulder. Table 28 Table 29 Fillet relief dimensions for ground shafts for high speed rotation and high operating tempera- the surface to the depth where the hardness is 513HV F shows the related dimensions. and housings unit: mm tures. However, because of gaps, this method is not (50HRC), and it is obtained by the following equation. For dimensions of the fillet relief when finishing the r s min always sufficient in preventing oil leakage and dust Smallest permissible Fillet relief dimensions entry when the machine is not in operation. Eht ≧ 0.8Dw(0.1 ＋ 0.002D w) ……………(36) shaft or housing by grinding, the values shown in Table 29 are recommended. single chamfer r where, E ht ：Minimum effective thickness of For other dimensions related to mounting, see the dimension t gs b 1 Oil groove G the hardened layer, mm related section for each bearing as required. 1 0.2 1.3 2 Oil grooves are provided on either the shaft or hous- D w ： Roller diameter, mm In addition, for ease in dismounting of bearings, it is 1.1 0.3 1.5 2.4 ing bore, or on both for more effective sealing (See 1.5 0.4 2 3.2 Generally, the required effective thickness of the convenient to make notches in the shoulder of the Fig. 14.). The clearance between the shaft and the 2 0.5 2.5 4 hardened layer is at least 0.3 mm. shaft or housing to allow the insertion of dismounting housing bore should be as small as possible, and the 2.1 0.5 2.5 4 H hooks. values shown in Table 30 are generally used, taking 3 0.5 3 4.7 into consideration errors in machining and assembly, 4 0.5 4 5.9 shaft deformation, etc. Three or more grooves are 5 0.6 5 7.4 made with a width of 3 ～ 5 mm and a depth of 4 ～ 5 6 0.6 6 8.6 I 7.5 0.6 7 10 mm. If the grooves are filled with grease, it will be more effective for dust prevention. As shown in Fig. 15, helical grooves are suitable for Sealing horizontal shafts which have a fixed direction of rota- tion. Right or left handed grooves are used according J To obtain the best performance of rolling bearings, it to the direction of rotation, and they are used for oil is necessary to prevent leakage of lubricant and the lubrication normally in conjunction with a suitable anti- dust device. K

Fig. 13 Dimensions related to mounting L

(1)(2)(3) Fig. 14 M

1N=0.102kgf=0.2248lbs. A45 1mm=0.03937inch A46 Table 30 Clearance between grooved shaft and 3 Labyrinth Contact type sealing method Table 33 Peripheral speed and surface roughness A housing bore unit: mm Although it is a little difficult to make, the labyrinth is of shaft very effective in preventing oil leakage especially at Peripheral speed m ／ s Surface roughness Shaft dia. Clearance In this type of sealing, the shaft is sealed by the appli- high speeds. At low speeds, filling the labyrinth with cation of pressure resulting from the elasticity of the Over Incl. μ mRa(μ mRy) grease is effective in preventing the entry of dust. In Incl. 50 mm 0.25 ～ 0.4 seal material to the sealing surface of the shaft, which － 5 0.8(3.2) Fig. 17, it is necessary to split the housing or cover B Over 50 mm 0.5 ～ 1 rotates, reciprocates or oscillates. Synthetic rubber, 5 10 0.4(1.6) plate into two. In Fig. 18, it is easy to assemble, and synthetic resin and felt are generally used as sealing 10 － 0.2(0.8) if combined with an oil seal, it improves the sealing materials. effect. Table 31 shows the labyrinth clearances generally 1 Oil seal 2 Felt seal C used. Synthetic rubber oil seals are the most general type of Because of their simple structure, felt seals have long sealing used. The sealing effect is obtained when the been used to protect grease lubrication from dust. elastic lip comes into contact with the shaft. Some Since felt absorbs some grease during operation, it lips are spring-loaded to maintain adequate pressing hardly causes heat generation and seizure, but it can- not be used when the peripheral speed of the shaft is D Fig. 15 force. The sliding surfaces of the lip and the shaft always high (more than 4 m/s). Where there is a high con- show frictional behavior such that the boundary lubri- centration of dirt and dust, they may become attached 2 Flinger cation and fluid lubrication are mixed. If there is an to the contact surface of felt, sometimes scratching The oil flinger is a disk attached to the shaft which insufficient amount of oil between the contact sur- the shaft surface. To prevent this, two felt seals are E throws off oil due to the centrifugal force of rotation (1) faces, it will cause heat generation, wear and seizure. placed apart from each other, or a felt seal is used and thus prevents oil leakage and the entry of foreign Conversely, if the oil film is too thick, it may cause oil together with a synthetic rubber seal. particles. Fig. 16 (1) shows an example in which the leakage. flinger is located inside the housing, mainly to prevent General oil seals are specified in JIS B 2402. F oil leakage. Since it sucks in dust and dirt, it should Oil Seals for Needle Roller Bearings (See page 486.) be used in a dust free environment. Fig. 16 (2) shows have a low sectional height to match the Needle an example in which the flinger is located outside the Roller Bearings. housing, and is used in combination with another Nitrile rubber is generally used as the material for oil (2) sealing device, to prevent entry of foreign particles. seal lips. Table 32 shows the materials and their G operating temperature ranges. The finished surface of the shaft where the seal lip Fig. 17 makes contact must have an appropriate surface roughness, as shown in Table 33, according to the H peripheral speed. It must also have accurate circular- ity, and the shaft eccentricity should be less than 0.05 (1) mm. To increase wear resistance, the hardness of the slid- I ing part of the shaft must be more than 40HRC. This can be achieved by hard-chrome plating or heat treat- ment.

(2) Table 32 Seal materials and operating temperatures J Fig. 18 Fig. 16 Seal material Operating temperature range ℃ Table 31 Labyrinth clearance unit: mm Nitrile rubber Clearance － 25 ～＋ 120 K Shaft dia. Acrylic rubber － 15 ～＋ 130 Radial direction Axial direction Synthetic rubber Silicon rubber － 50 ～＋ 180 Incl. 50 mm 0.25 ～ 0.4 1 ～ 2 Fluoro rubber － 10 ～＋ 180 Over 50 mm 0.5 ～ 1 3 ～ 5 Tetrafluoethylene resin － 50 ～＋ 220 L

M

1N=0.102kgf=0.2248lbs. A47 1mm=0.03937inch A48 Methods of lubrication Grease lubrication 2 Replenishment of grease A Lubrication The life of grease depends on its type and quality, the 1 Amount of grease to be filled type and dimensions of the bearing, operating condi- Purpose of lubrication Grease lubrication and oil lubrication are generally used for rolling bearings. In special cases, solid lubri- The amount of grease to be filled depends on the tions, temperature, amount of wear, penetration of for- cants are also used. housing structure, dimensions, type of grease used eign particles and water, etc. The main purpose of bearing lubrication is to reduce In general, grease lubrication requires the simplest and atmosphere. Generally, filling about 1/3 to 1/2 of Fig. 20 shows the replenishment intervals for grease, B friction and wear and to prevent heat generation and sealing device. It is therefore economical, and widely the free space inside of the bearing and the housing and is used as a general guideline. The values seizure. The lubricant and the lubricating method used. Also, once filled with grease, the bearing can is considered to be appropriate. Too much will cause obtained from this diagram apply to cases in which have a big influence on the operating performance of be used for a long period without replenishing the a rise in temperature, and care should be taken espe- the load condition is normal, the machine body is sta- the bearing, and it is therefore necessary to select grease. However, compared with oil, its heat removal cially at high speed rotations. tionary, and the operating temperature on the outer them suitably for the operating conditions. C properties and cooling capacity are inferior, since In Fig. 19, several grease pockets are provided by the surface of bearing outer ring is less than +70。 C. If The effects of lubrication are as follows. grease has high flow resistance, which causes high grease sectors on one side of the bearing. Even if the the temperature exceeds +70。 C, as a general rule, churning heat. filled grease is dispersed by the centrifugal force at the replenishment interval is halved for every 15。 C 1 Reduction of friction and wear Oil has greater fluidity and superior heat removal high rotational speeds, it is trapped by the grease increase. At the contact surfaces between the race rings, rolling D properties. It is therefore suitable for high-speed pockets and diverted back into the bearing again. Old elements and cage of the bearing, lubrication pre- operations. In addition, it is simple to filter out dust grease accumulates in the space on the opposite side vents metal-to-metal contact, and reduces friction and and dirt from oil. Thus it can prevent the generation of the bearing, and this can be removed periodically wear due to sliding and rolling, in the latter of which of noise and vibration and increase bearing life. by taking off the cover. micro-slips occur by differential slip, skew, spin, or Another advantage of oil lubrication is that it offers the E elastic deformation. possibility for selecting the appropriate method for particular operating conditions from among various 2 Elimination of frictional heat available lubrication methods. However, measures to The lubricant removes the heat generated by friction prevent oil leakage are required. As a guideline for or transferred from outside, and prevents overheating F selection, Table 34 compares grease and oil lubrica- of the bearing. Circulating lubrication is generally tion. used for this purpose. For the lubricants used for Spherical Bushings, see page K2. 3 Influence on bearing life G The bearing life is extended if the rolling contact sur- faces between the race rings and rolling elements are Table 34 Comparison between grease lubrication Fig. 19 separated by an oil film of adequate thickness, and is and oil lubrication shortened if the oil film is inadequate due to low oil Item Grease lubrication（1） Oil lubrication H viscosity, etc. Sealing, Simple Slightly complicated 4 Rust prevention Housing structure The lubricant prevents rust formation on the inside High temperature allowed and outside surfaces of the bearing. Temperature High temperature not allowed I (Cooling effect by circulation)

5 Dust prevention Rotational speed Low and medium speeds High speed allowed Grease lubrication is particularly effective for dust pre- vention. Oil circulating or jet lubrication is effective in Load Low and medium loads High load allowed J washing foreign particles away from the area around the bearing. Elaborate Maintenance Easy (Pay special attention to oil leaks. )

Lubricant replacement Slightly complicated Simple K

Lubrication performance Good Very good Remark d is the bore diameter of the inner ring. For a bearing without an inner ring, the roller set bore L Dust filtration Difficult Simple diameter F w is used for d. Fig. 20 Interval for replenishment of grease Dust and dirt can be removed by Entry of dust and dirt Easy measures for protection filtering in circulating lubrication.

Note(1) This represents bearing grease for general use. M

1N=0.102kgf=0.2248lbs. A49 1mm=0.03937inch A50 Oil lubrication oil flows along the grooves in the case and accumu- the bearing rotates together with the bearing forming Lubricants A lates in the oil pockets, keeping the oil level constant. an air wall. As shown in Fig. 24, the jet from the noz- 1 Oil bath lubrication So the oil is steadily supplied to the bearing. zle blows directly into the space between the inner For rolling bearings, lubricating grease or oil is gener- This is the most commonly used oil lubrication ring and the cage. Due to the large amount of oil ally used. For special applications, solid lubricants method, and is used for medium and low speeds. If being used, it is more effective to make the discharge are used. the amount of oil is too large, heat will be generated port larger, and use the forced discharge. B by churning, and if the amount is too small, seizure When the d mn value (mean value of the bearing out- Lubricating grease will occur. Therefore, the correct amount of oil must side and bore diameters in millimeter x rotational be maintained. When the machine is stationary, the speed in revolutions per minute) is more than Grease is a semi-solid lubricant made by mixing base correct oil level in the case of a bearing mounted on a 1,000,000, the speed of the jet should be 10～ 20 oil (liquid lubricant) and a thickener under heat and C horizontal shaft, is near the center of the lowest rolling m/s, the nozzle diameter should be about 1 mm, oil adding additives as required. element. In the case of a vertical shaft, about 50% of supply pressure should be 0.1 ～ 0.5 MPa, and the oil There are many types of grease according to various the surfaces of the rolling elements should be sub- supply amount should be about 500 cc/min or greater. combinations of base oil, thickeners and additives. Fig. 22 Oil splash lubrication merged in oil. When the rotational speed is higher, the oil supply Grease is usually classified by thickeners and base D It is desirable to provide an oil gauge so that the oil pressure and the oil amount should be higher. oil. Table 35 shows the general properties of each 4 Oil circulating lubrication level can be easily checked while the machine is sta- type of grease. When automatic lubrication is more economical tionary or running. because lubrication is required at many points, or when cooling is required for high rotational speed, this 2 Oil drip lubrication E method is used. The oil is supplied with a pump, Oil drips, which are fed down from a sight-feed oiler or which can control the oil pressure, and a filter or cool- along a fiber string, become an oil spray due to wind er, etc. can be set up in the circulation system, mak- pressure generated by the rotating cage, shaft, nut, ing this an ideal method of lubrication. As shown in etc., or they strike the rotating parts and form an oil Fig. 23, the oil supply and discharge ports are located F spray, which fills up the housing and every required opposite to each other, and the discharge port is part. Because oil spray removes frictional heat, this made large to prevent the accumulation of oil. method has a more effective cooling effect than the oil Fig. 24 Oil jet lubrication bath method, and is widely used for high-speed rota- tion and medium load conditions. G In the case of the sight-feed oiler (Fig. 21), the num- Table 35 Properties of various types of grease ber of drips can be adjusted. However, this is difficult Name (Common name) Calcium Sodium Aluminum Mixed base Barium Non-soap base grease Lithium grease using the string-feed method. The number of drips grease grease grease grease grease (Non-soap grease) depends on the bearing type, rotational speed, etc., Cup Fiber Mobile Diester Silicon Bentone H but 5 ～ 6 drips per minute is generally used. Item （）grease （）grease （）grease （）grease （）grease （）grease Base oil Mineral oil Mineral oil Mineral oil Mineral oil Mineral oil Mineral oil Diester oil Silicon oil Mineral oil Synthetic oil Na + Ca soap, Silica gel. Thickener Ca soap Na soap Al soap Ba soap Li soap Li soap Li soap Bentone Polyurea, Fig. 23 Oil circulating lubrication Li + Ca soap etc. I Fibrous and Stringy and Fibrous and Fibrous and Appearance Buttery Buttery Buttery Buttery Buttery Buttery 5 Oil mist lubrication buttery buttery buttery buttery After dirt and dust are removed by a filter, the oil is Pour point ℃ 80 ～ 90 150 ～ 180 70 ～ 90 160 ～ 190 150 ～ 180 170 ～ 190 170 ～ 190 200 ～ 250 200 ～ None turned into a spray by dry compressed air, and this Operating temperature range ℃ － 10 ～＋ 70 － 20 ～＋ 120 － 10 ～＋ 80 － 10 ～＋ 100 － 10 ～＋ 135 － 20 ～＋ 120 － 50 ～＋120 － 50 ～＋180 － 10 ～＋150 ～＋ 200 J lubricates the bearing. When the air and oil pass Pressure resistance Strong to weak Strong to medium Strong Strong Strong to medium Medium Medium Weak Medium to weak Medium Fig. 21 Oil drip lubrication through the bearing, the air cools the bearing and the Good, poor for Na+ oil lubricates it. In addition, because the air inside the Water resistance Good Poor Good Good Good Good Good Good Good Ca soap grease 3 Oil splash lubrication housing is at a higher pressure than the outside air, In this method, oil is splashed in all directions by the the entry of water and foreign particles is prevented. Mechanical stability Fair Good Poor Good Poor Excellent Excellent Excellent Good Good to poor K rotation of the gear or disk. This can be used for con- There are many other advantages of this method, and Contains about Long fibrous It has water Usable at fairly It has water This is the best Excellent Mainly used Generally good heat resis- siderably high-speed rotations without soaking the it is suitable for high rotational speed applications 1% water. grease cannot and rust resis- high speeds. and heat resis- all-purpose under low for high tem- tance. Grease having a miner- When the tem- withstand high tant proper- tant proper- grease among temperature peratures. Not al base oil is for general use. bearing directly in oil. such as high speed internal grinding spindles. perature rises speeds, but ties, and ties. This is an soap based conditions and suited to high Grease having a synthetic base In the gear case where shafts and bearings are lubri- to more than has good pres- adheres easily all-purpose greases. has superior speeds and oil is suitable for special use L +80゜C, the sure resis- to metal sur- grease. frictional prop- heavy loads. where superior heat and chem- cated with the same oil, wear particles may be intro- 6 Oil jet lubrication Features and application water evapo- tance proper- face. erties. ical resistance properties are duced into the bearing as they might get mixed with This is a highly reliable lubrication method and is used rates and the ties. Short Suitable for required. grease sepa- fibrous grease small bearings the oil. In this case, a permanent magnet is provided under severe conditions such as ultra-high rotational rates into oil is compara- used in mea- at the bottom of the gear case to collect metal parti- speeds and high temperatures. The speed of the oil and soap. This tively good for suring instru- is used for high speeds. ments. M cles, or a shield plate is installed next to the bearing. jet should be more than 20% of the peripheral speed medium loads. Fig. 22 shows another method in which the splashed of the inner ring raceway surface, since the air around

1N=0.102kgf=0.2248lbs. A51 1mm=0.03937inch A52 1 Base oil running for long periods of time, its temperature rises. A Petroleum lubricating oil is usually used as the base This results in oxidation of the lubricant and formation oil. of oxides, which lead to corrosion of the bearing. As the lubricating performance of grease depends Thus, when a bearing is to be operated for long peri- mainly on that of base oil, the viscosity of the base oil ods of time without regreasing, antioxidants are is an important property. In general, low viscosity is added. In addition, grease containing extreme pres- B suitable for light-load and high-speed rotations, and sure additives is suitable for use in places that are high viscosity for heavy-load and low-speed rotations. subjected to heavy loads. Synthetic lubricants of the diester or silicon series are used instead of lubricants of the petroleum series in 5 Miscibility of different greases C consideration of the pour point and high temperature In principle, it is desirable to use grease of the same stability. brand. However, when the mixing of different greases is unavoidable, greases with the same type of thick- 2 Thickener ener and with a similar type of base oil should be As shown in Table 35, metal soap bases are mostly used. D used as thickeners. In particular, Na-soap is water- It should be noted that if different types of grease are soluble and emulsifies easily, and it cannot be used in mixed, they may interact with each other and the con- damp or wet areas. The type of thickener and the sistency will become softer than that for the individual pour point of grease have a close relationship. In greases. E general, the higher the pour point, the higher the max- imum usable temperature of grease. However, even Lubricating oil Fig. 25 Relationship between viscosity and temperature of lubricating oil when the grease uses a thickener having a high pour point, its upper operating temperature limit is low if its For rolling bearings, refined mineral oil or synthetic oil F base oil has low heat resistance. is used. To improve its properties, antioxidant addi- Table 38 Conditions of bearing use and examples of lubricating oil selection tives, extreme pressure additives and detergent addi- ISO viscosity grade(VG) 3 Consistency tives are added as required. Conditions This represents the hardness grade of grease. When selecting lubricating oil, it is important to select 10 15 22 32 46 68 100 150 220 320 460 680 G Grease becomes harder in proportion to the amount oil which has adequate viscosity under operating tem- Refrigerator oil

of thickener if the same thickener is used. peratures. If the viscosity is too low, the formation of － 30 ～ 0 ℃ s s

Immediately after grease has been stirred (usually 60 the oil film will be insufficient, causing abnormal wear s Bearing oil times), a depression is formed in the grease in a and seizure. On the other hand, if the viscosity is too s

0 ～ 50 ℃ s Turbine oil specified time using a specified cone. The consisten- high, it will generate excessive heat or increase power s H

cy (combined consistency) is expressed by the value loss due to viscous resistance. As a general stan- s Bearing oil s

of depth of depression (mm) multiplied by 10. dard, oil having higher viscosity should be used for 50 ～ 80 ℃ s Turbine oil This value gives an estimate of the fluidity during heavier loads and oil having lower viscosity should be s

operation with a greater value for softer grease. used for higher rotational speeds. Operating temperature s Bearing oil

Table 36 shows the consistency number of grease Under conditions of normal use for various bearings, s I

80 ～ 110 ℃ Turbine oil Gear oil

s

and the relationship between the consistency and the values of viscosity shown in Table 37 will be a s s s operating conditions. guideline. s d n value Large s Small

The relationship between viscosity and temperature m Load Small s sLarge Table 36 Consistency and operating conditions of grease can be obtained from Fig. 25. Also, Table 38 shows J examples of selecting lubricating oil according to the Remarks ・Lubricating oils are based on JIS K 2211 (Refrigerator Oil), JIS K 2239 (Bearing Oil), JIS K 2213 (Turbine Oil), and JIS K 2219 NLGI (Gear Oil). Combined consistency Application conditions of bearing use. consistency number ・ The method of lubrication in these cases is mainly oil bath lubrication or circulating lubrication. ・ When the temperature is on the high side within the operating temperature range, oils of high viscosity are used. 0 385 ～ 355 For centralized lubrication, ・ d n represents the mean value of the bore and outside diameters (mm) of the bearing multiplied by the rotational speed (rpm). Table 37 Bearing series and required viscosity of lubricating oil m K 1 340 ～ 310 For oscillating motion Kinematic viscosity at 2 295 ～ 265 For general use Bearing series operating temperatures 3 250 ～ 220 For general use, For high temperature Needle roller bearings 4 205 ～ 175 For sealing with grease 13 mm2/s or more Roller bearings L

4 Additives Crossed roller bearings 20 mm2/s or more Additives include various types of substances, which Thrust needle roller bearings are added to grease in small quantities to improve its 32 mm2/s or more Thrust roller bearings M characteristics. For example, when a bearing is kept

1N=0.102kgf=0.2248lbs. A53 1mm=0.03937inch A54 C-Lube Bearing ・To ensure normal rotation of the bearing, apply a Friction and Allowable Allowable rotational speed A load of 1% or more of the basic dynamic load rating C-Lube Bearing is a bearing that is lubricated at use. Rotational Speed As the rotational speed of rolling bearings is with a newly developed thermosetting solid-type lubri- ・The allowable rotational speed is different from that increased, the bearing temperature also increases cant. A large amount of lubricating oil and fine parti- of the general needle roller bearings. See the val- Friction due to the heat generated at the contact surfaces cles of ultra high molecular weight polyolefin resin are ues shown in Table 39. between the cage, raceways and rolling elements, B solidified by heat treatment to fill the inner space of Compared with sliding bearings, the starting (static) until it finally leads to bearing seizure. It is therefore the bearing. As the bearing rotates, the lubricating oil friction for rolling bearings is small, and the difference necessary to maintain the rotational speed of a bear- oozes out onto the raceway in proper quantities, between the starting (static) friction and the kinetic ing below a certain limit value to ensure safe opera- maintaining the lubrication performance for a long friction is also small. The loss of power and tempera- tion for long periods. This limit value is called the C period of time. Solid-type lubricant ture rise in machines are thus reduced, improving the allowable rotational speed. C-Lube Bearing is available in all Needle Roller mechanical efficiency. Since the amount of heat generated is approximately Bearing series with an outer diameter not exceeding Frictional torque is influenced by the bearing type, proportional to the sliding speed at the contact area, 80 mm. Also, C-Lube Bearing with food grade oil is bearing load, rotational speed, lubricant characteris- this sliding speed is an approximate guide indicating D available For Food machinery. When required, please tics, etc. It varies according to the lubricant when the limit of the bearing rotational speed. consult for further information. operated under light-loads and high-speed conditions, The allowable rotational speed of bearings thus varies and according to the load when operated under according to the bearing type, size, bearing load, Features of C-Lube Bearing Needle roller heavy-loads and low-speed conditions. method of lubrication, radial clearance, and other Frictional torque of rolling bearings is complicated such factors. E ・Most suitable for preventing grease dry-up in appli- because it is influenced by various factors, but for The allowable rotational speeds shown in the table of cations where lubrication is difficult. convenience, it can be expressed approximately by dimensions are empirical values. They are not Outer ring ・Great reduction of maintenance work by extending the following equations. absolute values and can be changed according to the the lubrication interval. bearing use conditions. Depending on the structure F d ・Elimination of oil contamination, making this bear- Structure of C-Lube Bearing ・ Radial bearings M＝μP ……………………(37) and accuracy around the bearing, the lubricant and 2 ing most suitable for applications that would be the lubrication method, it is possible for some bear- d adversely affected by oil. ・ Thrust bearings M＝μP m ……………………(38) ings to be operated at more than twice the allowable 2 rotational speed given in the table without trouble. Table 39 Allowable rotational speed of C-Lube Bearing Cautions for using C-Lube Bearing G where, M ： Frictional torque, N-mm Type (representative) Allowable dn values 1 2 μ ： Coefficient of friction ・Never wash C-Lube Bearing with organic solvent Model code (representative) dm（n ）、d1（n ） P ： Bearing load, N and/or white kerosene which have the ability to Machined type needle roller bearing NA，TR，TAF，NAF 20 000 d ：Bearing bore diameter, mm remove fat, or leave the bearing in contact with Shell type needle roller bearing TA…Z，TLA…Z 20 000 H d m ：Mean value of bearing bore and these agents. Cam follower CF…W 10 000 outside diameters, mm ・The operating temperature range is -15 ～+80。 C. 1 Notes( ) dmn ＝＝（bore diameter of bearing［mm］＋ outside diameter of bearing［mm］） For continuous operation, the recommended oper- /2 × rotational speed［rpm］ 2 ating temperature is +60。 C or less. ( ) d1n ＝＝ stud diameter［mm］× rotational speed［rpm］ The approximate coefficients of friction of Bearings under operating conditions, in which lubrica- I tion and mounting are correct and where loads are relatively large and stable, are shown in Table 40.

Rotational endurance test 100 Table 40 Coefficient of friction J Test condition C-Lube Cam Follower Test product C-Lube Cam Follower: CF10/SG Bearing series μ Standard Cam Follower: CF10 75 Rotational speed : 1,000rpm Ambient temperature : Room temperature Needle roller bearings with cage 0.0010 ～ 0.0030 K 50 Full complement needle roller bearings 0.0030 ～ 0.0050 Thrust needle roller bearings 0.0030 ～ 0.0040 Standard Cam Follower Thrust roller bearings 0.0030 ～ 0.0040 25 L Residual oil content ratio in the bearing % 0 0 1 000 2 000 3 000 4 000 5 000 Operation time min. M

1N=0.102kgf=0.2248lbs. A55 1mm=0.03937inch A56 Methods of mounting When press fitting, the friction of the fitting surfaces A Operating Temperature Range Handling of Bearings can be reduced by applying high viscosity oil over the Mounting methods of bearings are different according fitting surfaces. The allowable operating temperature range for needle Precautions in handling to the type of bearing and the fit. In general, mount- The pressing-in or pulling-out force to be applied to roller bearings is generally -20 ～ +120。 C. ing of needle roller bearings is comparatively easy. the bearing is given on page A59. When operating at temperatures outside this range, Since the bearing is a high-accuracy mechanical ele- However, non-separable bearings with large interfer- B the operation may be limited by the allowable temper- ment, special attention must be paid to its handling. ences should be handled with great care. 2 Mounting by shrink fitting ature range of prepacked grease, seal, cage material, The following precautions should be noted when han- This method is used when the interference is great or etc. dling the bearings. 1 Mounting by press fit when a large bearing is to be fitted. The housing is The operating temperature range for some types of Small and medium bearings with small interferences heated and thermally expanded when fitting the outer bearings is different from the above. See the section C 1 Bearings and their surrounding parts should be kept clean. require a small pressing-in force for mounting, and ring to the housing and the inner ring is heated and for each bearing. Bearings and their surrounding parts must be kept they are mounted using a press at room temperature. expanded when fitting it to the shaft allowing the bear- clean paying special attention to dust and dirt. Tools The bearing should be pressed in carefully, applying a ing to be set easily within a short time. The maximum and the working environment should also be cleaned. force evenly to the bearing with a fitting tool as shown allowable temperature for the shrink fit is +120。C, and in Fig. 26. For separable bearings, the inner and heating should be performed appropriately. Pure D 2 Bearings should be handled carefully. outer rings can be mounted separately, and the non-corrosive mineral oil is recommended as the A shock load during handling may cause scratches, mounting work is simple. However, when installing heating oil for shrink fit, and insulation oil for trans- indentations and even cracks or chips on the raceway the shaft and inner ring assembly into the outer ring, formers is considered to be the best. During cooling, surfaces and rolling elements. care should be taken not to damage the raceway sur- the bearing also shrinks in the axial direction. E faces and rolling elements. Therefore, to ensure that there is no clearance 3 Bearings should be mounted or dismounted with proper tools. between the bearing and the shoulder, an axial force When mounting and dismounting, tools suitable for must be applied continuously to the bearing until it the bearing type should be used. has cooled. F When the interference between the outer ring and the 4 Bearings should be protected against corrosion. housing is great, an expansion fit method in which the Bearings are treated with anti-corrosive oil. However, bearing is cooled using dry ice or other cooling agent when handling them with bare hands, sweat from the before fitting can be used. Immediately after fitting, hands may result in future rust formation. Gloves however, moisture from the air easily condenses on G should be worn, or hands should be dipped in mineral the bearing. Therefore, it is necessary to take pre- oil. ventive measures against corrosion.

Fig. 26 Mounting H When mounting non-separable bearings, the inner Preparation and outer rings are pressed in simultaneously by applying a cover plate as shown in Fig. 27. It must Before mounting the bearing, the dimensions and fil- never happen that the inner ring is press-fitted to the I lets of the shaft and housing should be checked to shaft by striking the outer ring, or the outer ring by ensure that they conform to specifications. striking the inner ring, because the raceway surfaces Bearings should be unwrapped just before mounting. and rolling elements will be scratched or indented. In case of grease lubrication, bearings should be filled J with grease without cleaning the bearings. Even in the case of oil lubrication, it is normally unnecessary to clean the bearings. However, when high accuracy is required or when using at high speeds, the bear- ings should be cleaned using cleaning oil to remove K thoroughly oily contents. The cleaned bearings should not be left alone without anti-corrosive precau- tions, because bearings can easily be corroded after anti-corrosive agents are removed. L Lubricating grease is prepacked in some types of bearings. Therefore, refer to the relevant section for Fig. 27 each bearing. M

1N=0.102kgf=0.2248lbs. A57 1mm=0.03937inch A58 Pressing force and pulling force Dismounting Dismounting of inner ring A

Guidelines for the pressing force when pressing in the Dismounting of the bearings is carried out for the peri- In the case of bearings such as needle roller bearings inner ring to the shaft and the pulling force when odic inspection or repairs of machines. By inspecting in which the inner and outer rings are separable, the pulling it out are obtained from the following equation. the bearing, related parts or mechanisms, lubrication, simplest way to press out the inner ring is by using a etc., important data is obtained. In the same manner press as shown in Fig. 29. B 2 d ∆ d as in mounting, care should be taken to prevent dam- The puller shown in Fig. 30 is also generally used. K＝ f k df｛｝B 1 － ………(39) d＋ 2 ( F ) age to the bearing or other parts. This is designed according to the bearing size. In addition, there are a 3-hook puller (Fig. 31) and a 2- where, K ： Pressing or pulling force, N A suitable dismounting method should be selected according to the type of the bearing, fit, etc. Bearings hook puller for wide-range use. C f k ： Resistance factor determined by the coefficient of friction 4 mounted by interference fit are especially difficult to When pressing in inner ring to shaft, f k=4 × 10 dismount, and it is necessary to give due considera- Fig. 31 When pulling out inner ring from shaft, f =6 × 104 k tion to the structure around the bearing during the d ： Bore diameter of inner ring, mm design stage. ∆ In addition to these, when it is difficult to remove the df ： Apparent interference, mm D inner ring due to high shoulders, several holes for B ： Width of inner ring, mm Dismounting of outer ring removal pins are made through the shoulder, or sev- F ： Outside diameter of inner ring, mm eral hook grooves are cut in the shoulder as shown in The actual pressing force or pulling force may be Outer rings mounted by interference fit are dismount- Fig. 32 and Fig. 33. greater than the calculated value due to mounting ed as shown in Fig. 28, by screwing in the push-out When a bearing is not to be used again after removal, E errors. When designing a puller, it is necessary that bolts evenly through several screw holes provided at it may be removed by heating with a torch lamp. the puller has the strength (rigidity) to withstand more places corresponding to the side face of the outer than 5 times the calculated value. ring. F Running test

After mounting the bearing, a running test is carried out to check whether the mounting is normal. G Usually, it is first checked by manual turning. Then, it is operated by power gradually from no-load and low- speed up to normal operating conditions to check for abnormalities. H Noise can be checked by using a soundscope or simi- Fig. 29 Fig. 32 lar instrument. In this test, checks are carried out for the following abnormalities. Fig. 28

1 Manual turning I (a) Uneven torque ……………… Improper mounting (b) Sticking and rattling …Scratches or indentations on the raceway surface (c) Irregular noise… Penetration of dust or foreign J particles

2 Power running (a) Abnormal noise or vibration… Indentations on K the raceway surface, too great clearance Fig. 30 Fig. 33 (b) Abnormal temperature … Unsuitable lubricant, improper mounting, too small clearance L

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1N=0.102kgf=0.2248lbs. A59 1mm=0.03937inch A60 Inspection of bearing Maintenance and inspection Table 41 Damage, causes and corrective action A

Condition of bearing damage Cause Corrective action Cleaning of bearing Maintenance and inspection

Flakings at opposite circumferential positions on raceway Improper roundness of housing bore Correction of housing bore accuracy When inspecting a bearing after removal, the appear- Maintenance and inspection are carried out to main- surfaces ance of the bearing should be recorded first. Then, tain good performance of bearings installed in the B Flakings in the vicinity of raceway surface edges and roller Improper mounting, Shaft deflection, Poor Careful mounting, Careful centering, Correction after the residual amount of lubricant is checked and machine. ends centering, Poor accuracy of shaft or housing of shoulders of shaft and housing for right angles a sample of lubricant is collected, the bearing should Maintenance is performed by checking the machine Flakings on raceway surfaces with an interval corresponding to Great shock load when mounting, Rusting Careful mounting, Protection against rust for be cleaned. operating conditions, checking and replenishing or Flaking roller pitch during machine stoppage long periods of machine stoppage For cleaning, light oil or kerosene is commonly used. replacing the lubricant, checking the bearing and C Too small clearance, Too great load, Poor Correct selection of fit and clearance Cleaning is divided into rough cleaning and final related parts by periodic disassembly and other such Early flaking on raceway surfaces and rolling elements cleaning, and wire gauze is set as a raised bottom in procedures. lubrication, Rusting, etc. Correct selection of lubricant Poor lubrication in early stage a container to prevent the bearing from touching the Items for inspection of a running bearing in a machine Selection of softer grease, Galling on raceway surfaces and rolling surfaces of rollers Grease consistency too hard bottom of the container. include the bearing temperature, noise, vibration and Avoiding quick acceleration D Lubricating grease and adhering substances such as condition of lubricant. High acceleration at start foreign particles are removed with a brush, etc., When any abnormality is found during operation, the Galling Poor lubrication, Poor mounting, Correct selection of lubricant Galling between roller end faces and collar guide surfaces using oil for rough cleaning. Care should be taken cause should be investigated and measures taken by Large axial load Correct mounting during this process, because if the bearing is turned referring to the section on running test on page 62. Excessive shock load, Too much interference. Reevaluation of load conditions, Correction of fit, with foreign particles attached, the raceway surfaces When removing a bearing, refer to the section on dis- Poor cylindricity of shaft. Too large fillet radius, Correction of machining accuracy of shaft or E Cracks in outer or inner ring may be scratched. mounting on page A59. Development of thermal cracks, sleeve, Making fillet radius smaller than the Final cleaning is carried out by turning the bearing in Development of flaking chamfer dimension of bearing Development of flaking cleaning oil. It is desirable that the cleaning oil is kept Damage, causes and corrective action Cracked rolling elements, Shock to collar when mounting, Careful handling and mounting clean by filtering. Immediately after cleaning, the Breakage broken collar F bearing must be protected against corrosion. Rolling bearings can generally be used fully up to Dropped by careless handling their rolling fatigue life if they are properly selected, Abnormal load to cage by poor mounting, Minimizing mounting errors, Broken cage Inspection and evaluation of bearing mounted, operated and maintained. However, they Poor lubrication Study of lubricating method and lubricant may actually be damaged earlier than their expected Indentations on raceway surfaces at an interval Shock load applied when mounting, Careful handling The judgement as to whether the removed bearing is lifetimes creating problems or accidents. Common corresponding to the pitch between rolling elements (brinelling) Excessive load while stopping G

reusable depends on the inspection after cleaning. causes of damage include improper mounting or han- Dent Biting of foreign substances such as Cleaning of housing, Improvement of sealing, Indentation on raceway surfaces and rolling surfaces of rollers Conditions of the raceway surfaces, rolling elements dling, insufficient lubrication and penetration of foreign metal chips and sands Use of clean lubricant and fitting surfaces, wear condition of the cage, particles. Vibration when the bearing is stationary such Fixing of shaft and housing, False brinelling increase of bearing clearance, dimensions, rotational It may be difficult to determine the exact cause of a as during transportation, Use of lubricating oil, H (Phenomenon like brinelling) accuracy, etc. should be checked for damage and problem by checking only the damaged bearing. The Oscillating motion with small amplitude Application of preload to reduce vibration abnormalities. conditions of the machine before and after the occur- Fretting Increase of interference, The evaluation is performed based on the experience rence of the damage, the location and the operating Localized wear of fitted surfaces accompanied by red-brown Sliding between fitted surfaces Application of oil taking into consideration the degree of damage, and ambient conditions of the bearing, the structure wear particles I machine performance, importance of the machine, around the bearing, etc. should also be examined. It Wear on raceway surfaces, collar surfaces, rolling surfaces of Penetration of foreign particles, Poor Improvement of sealing, Cleaning of housing Abnormal wear operating conditions, period until the next inspection, then becomes possible to assess the cause of the rollers, cages, etc. lubrication, Rust Use of clean lubricant and other such factors. damage by linking the conditions of the damaged Creep Sliding between fitted surfaces, Increase of interference, bearing to the probable causes arising from the Wear on fitted surfaces Insufficient tightening of sleeve Correct tightening of sleeve machine operation, and to prevent the recurrence of J Supply of proper amount of proper lubricant, similar problems. Discoloration of rolling elements and/or raceway surfaces Poor lubrication, Too small clearance, Poor Rechecking of fit and bearing clearance Common types of damage, causes and corrective and/or flange surfaces, Adhesion and welding, Discoloration of mounting Rechecking of mounting dimensions and related Seizure cage action are listed in Table 41. parts Insulation of bearing, K Ripples on raceway surfaces Melting by sparks due to electric current Grounding to avoid electric current Electric corrosion Careful storage if under high temperature and Rust or corrosion on bearing inside surfaces or Condensation of vapor in air, high humidity, Protection against rust,

Rust, on fitted surfaces Penetration of corrosive substances Improvement of sealing corrosion L

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1N=0.102kgf=0.2248lbs. A61 1mm=0.03937inch A62 A63