Vickers® General Product Support

Hydraulic Hints & Trouble Shooting Guide

Revised 8/96 694

General Hydraulic Hints ...... 3

Troubleshooting Guide & Maintenance Hints ...... 4

Chart 1 Excessive Noise ...... 5

Chart 2 Excessive Heat ...... 6

Chart 3 Incorrect Flow ...... 7

Chart 4 Incorrect Pressure ...... 8

Chart 5 Faulty Operation ...... 9

Quiet Hydraulics ...... 10

Contamination Control ...... 11

Hints on Maintenance of Hydraulic Fluid in the System...... 13

Aeration ...... 14

Leakage Control ...... 15

Hydraulic Fluid and Temperature Recommendations for Industrial Machinery...... 16

Hydraulic Fluid and Temperature Recommendations for Mobile Hydraulic Systems...... 19

Oil Viscosity Recommendations ...... 20

Pump Test Procedure for Evaluation of Antiwear Fluids for Mobile Systems...... 21

Oil Flow Velocity in Tubing ...... 23

Pipe Sizes and Pressure Ratings ...... 24

Preparation of Pipes, Tubes and Fittings Before Installation in a Hydraulic System...... 25

ISO/ANSI Basic Symbols for Fluid Power Equipment and Systems...... 26

Conversion Factors ...... 29

Hydraulic Formulas ...... 29

2 General Hydraulic Hints

Good Assembly Pipes Tubing Do’s And Don’ts Practices Iron and steel pipes were the first kinds Don’t take heavy cuts on thin wall tubing of plumbing used to conduct fluid with a tubing cutter. Use light cuts to Most important – cleanliness. between system components. At prevent deformation of the tube end. If All openings in the reservoir should be present, pipe is the least expensive way the tube end is out or round, a greater to go when assembling a system. possibility of a poor connection exists. sealed after cleaning. Seamless steel pipe is recommended No grinding or welding operations for use in hydraulic systems with the Ream tubing only for removal of burrs. should be done in the area where pipe interior free of rust, scale and dirt. DO NOT over ream tubing as it can hydraulic components are being weaken the connection. Early classifications of pipe wall installed. thicknesses were: standard, extra heavy Do not allow chips to accumulate in the All cylinder, valve, pump and hose and double extra heavy. tubing. They can be difficult to remove connections should be sealed and/or after bending. Today, pipes are classified by schedule capped until just prior to use. number as specified by the American Follow the manufacturers Mineral spirits should be kept in safety National Standards Institute (ANSI). The recommendations on the use of flaring containers. schedule numbers vary from 10 through tools. Don’t overtighten the feed screw 160. The larger the number, the heavier handle on a compression type flaring tool. Air hoses can be used to clean fittings the wall thickness. The outer pipe Improper use of a tool can cause washout and other system components. However, diameter stays the same for a given pipe and/or splitting of the flare connection. the air supply must be filtered and dry to size, while the inside opening becomes prevent contamination of the parts. smaller as schedule number increases. Bend tubing instead of cutting and using a fitting. This reduces pressure drop and Examine pipe fittings and hose A comparison of early classifications minimizes system losses. The minimum assemblies prior to use to be certain that versus the ANSI classification follows: radius of a tubing bend should be at burrs, dirt and/or scale are not present. least three times the inside diameter of Standard – Schedule 40 the tube. Larger bends are preferred. All pipe and tubing ends should be Extra Heavy – Schedule 80 reamed to prevent restriction and Sketch the optimum tubing route before turbulent flow. The double extra heavy classification beginning the bending process. Be sure does not compare with a schedule to use tubing with the proper temper to Do not use Teflon tape on straight number. However, the inside diameter of prevent wrinkles and flattened bends. thread connections. a double extra heavy pipe is approximately one half that of a schedule Most flares are made by hand or power When installing pumps or motors, 160 pipe. tools that swage the tube end over a always align coupling halves as closely split die. The standard flare angle is 37 as possible, within 0.007 inch. In many cases, flanges are welded to degrees from the centerline. For best the pipe ends and gaskets or “O” rings results, heavy wall tubing should be cut, When using flexible couplings, follow the are used to seal the connections. deburred, and flared and bent using manufacturer’s recommendations or Various pipe fittings are used to route power equipment. allow 1/32 to 1/16 inch clearance the piping to and from each system between the coupling halves. component. These fittings can be For information on sealing technology, or threaded or welded in place as the need how to prevent leakage of hydraulic fluid, Do not drive couplings on pump or arises. Threaded connections are used refer to “Leakage Control” in this catalog. motor shafts. They should be a slip fit, in low pressure applications and welded or shrunk on using hot oil. connections are used if high pressure, Always use a dry spray-on lubricant on high temperature, or a severe splines when installing. This prevents mechanical load exists. wear and adds to the life of the splines. All piping should be secured with When using double universal joint clamps to prevent vibration and couplings, the shafts must be parallel excessive stress due to the weight of and the yokes must be in line. the fluid. Do not weld the clamps to the pipe as it may weaken the pipe and When installing V-belt pulleys on pumps cause a stress crack. or motors, line up both pulleys as closely as possible. Always install the pulleys with a minimum amount of overhang as close to the pump or motor face as possible. This increases bearing service life.

3 Troubleshooting Guide & Maintenance Hints

1. Know the capabilities of the system. 1. Excessive heat means trouble. A General Each component in the system has a misaligned coupling places an The troubleshooting charts and maximum rated speed, torque or excessive load on bearings and can maintenance hints that follow are of a pressure. Loading the system beyond be readily identified by the heat general system nature but should the specifications simply increases generated. A warmer than normal provide an intuitive feeling for a specific the possibility of failure. tank return line on a relief valve system. More general information is indicates operation at relief valve covered in the following paragraphs. 2. Know the correct operating pressures. setting. Hydraulic fluids which have a Effect and probable cause charts Always set and check pressures with a low viscosity will increase the internal appear on the following pages. gauge. How else can you know if the leakage of components resulting in a operating pressure is above the heat rise. Cavitation and slippage in a maximum rating of the components? pump will also generate heat. System Design The question may arise as to what the correct operating pressure is. If it isn’t 2. Excessive noise means wear, There is, of course, little point in correctly specified on the hydraulic misalignment, cavitation or air in the discussing the design of a system which schematic, the following rule should be fluid. Contaminated fluid can cause a has been operating satisfactorily for a applied: relief valve to stick and chatter. These period of time. However, a seemingly noises may be the result of dirty filters, uncomplicated procedure such as The correct operating pressure is the or fluid, high fluid viscosity, excessive relocating a system or changing a lowest pressure which will allow drive speed, low reservoir level, loose component part can cause problems. adequate performance of the system intake lines or worn couplings. Because of this, the following points function and still remain below the should be considered: maximum rating of the components and machine. 1. Each component in the system must Maintenance be compatible with and form an Once the correct pressures have been Three simple maintenance procedures integral part of the system. For established, note them on the hydraulic have the greatest effect on hydraulic example, an inadequate size filter on schematic for future reference. system performance, efficiency and life. the inlet of a pump can cause cavitation and subsequent damage to 3. Know the proper signal levels, 1. Maintaining a clean sufficient quantity the pump. feedback levels, and dither and gain of hydraulic fluid of the proper type settings in servo control systems. If and viscosity. 2. All lines must be of proper size and they aren’t specified, check them free of restrictive bends. An when the system is functioning 2. Changing filters and cleaning undersized or restricted line results in correctly and mark them on the strainers. a pressure drop in the line itself. schematic for future reference. 3. Keeping all connections tight, but not 3. Some components must be mounted to the point of distortion, so that air is in a specific position with respect to excluded from the system. other components or the lines. The Developing Systematic housing of an in-line pump, for Procedures example, must remain filled with fluid to provide lubrication. Analyze the system and develop a Guidelines logical sequence for setting valves, The following charts are arranged in five 4. The inclusion of adequate test points mechanical stops, interlocks and main categories. The heading of each for pressure readings, although not electrical controls. Tracing of flow paths one is an effect which indicates a essential for operation, will expedite can often be accomplished by listening malfunction in the system. For example, troubleshooting. for flow in the lines or feeling them for if a pump is exceptionally noisy, refer to warmth. Develop a cause and effect Chart 1 titled Excessive Noise. The troubleshooting guide similar to the noisy pump appears in Column A under Knowing the System charts appearing on the following pages. the main heading. In Column A there are The initial time spent on such a project four probable causes for a noisy pump. Probably the greatest aid to could save hours of system down-time. The causes are sequenced according to troubleshooting is the confidence of the likelihood of happening or the ease knowing the system. The construction and of checking it. The first cause is operating characteristics of each one Recognizing Trouble cavitation and the remedy is “a”. If the should be understood. For example, first cause does not exist, check for knowing that a solenoid controlled Indications cause number 2, etc. directional valve can be manually actuated The ability to recognize trouble will save considerable time in isolating a indications in a specific system is defective solenoid. Some additional usually acquired with experience. practices which will increase your ability However, a few general trouble and also the useful life of the system indications can be discussed. follow:

4 Troubleshooting Guide & Maintenance Hints

Chart 1 EXCESSIVE NOISE

A B C

PUMP NOISY MOTOR NOISY RELIEF VALVE NOISY

1. Cavitation 1. Coupling misaligned 1. Setting too low or too Remedy: a Remedy: c close to another valve setting Remedy: d

2. Air in fluid 2. Motor or coupling 2. Worn poppet and seat Remedy: b worn or damaged Remedy: e Remedy: b 3. Coupling Misaligned Remedy: c

4. Pump worn or damaged Remedy: e

Remedies: a. Any or all of the following: b. Any or all of the following: c. Align unit and check condition of seals, bearings and coupling. Replace dirty filters; wash strainers in Tighten leaking connections; fill solvent compatible with system fluid; reservoir to proper level (with rare d. Install pressure gauge and adjust to clean clogged inlet line; clean or exception all return lines should be correct pressure. replace reservoir breather vent; below fluid level in reservoir); bleed change system fluid; change to air from system; replace pump shaft e. Overhaul or replace. proper pump drive motor speed; seal (and shaft if worn at seal overhaul or replace supercharge journal). pump; fluid may be too cold.

5 Troubleshooting Guide & Maintenance Hints

Chart 2 EXCESSIVE HEAT

A B C D

PUMP HEATED MOTOR HEATED RELIEF VALVE HEATED FLUID HEATED

1. 1. Fluid heated 1. Fluid heated 1. System pressure too Remedy: See column D Remedy: See column D Remedy: See column D high Remedy: d

2. Cavitation 2. Relief or unloading 2. Valve setting incorrect 2. Unloading valve set Remedy: a valve set too high Remedy: d too high Remedy: d Remedy: d

3. Air in fluid 3. Excessive load 3. Worn or damaged valve 3. Fluid dirty or low supply Remedy: b Remedy: c Remedy: e Remedy: f

4. Relief or unloading 4. Worn or damaged 4. Incorrect fluid valve set too high motor viscosity Remedy: d Remedy: e Remedy: f

5. Excessive load 5. Faulty fluid cooling system Remedy: c Remedy: g

6. Worn or damaged 6. Worn pump, valve, motor, pump cylinder or other component Remedy: e Remedy: e Remedies: a. Any or all of the following: c. Align unit and check condition of g. Clean cooler and/or cooler strainer; seals and bearings; locate and replace cooler control valve; repair or Replace dirty filters; clean clogged correct mechanical binding; check for replace cooler. inlet line; clean or replace reservoir work load in excess of circuit design. breather vent; change system fluid; change to proper pump drive motor d. Install pressure gauge and adjust to speed; overhaul or replace correct pressure (keep at least 125 supercharge pump. PSI difference between valve b. Any or all of the following: settings). Tighten leaking connections; fill e. Overhaul or replace. reservoir to proper level (with rare exception all return lines should be f. Change filters and also system fluid if below fluid level in reservoir); bleed improper viscosity; fill reservoir to air from system; replace pump shaft proper level. seal (and shaft if worn at seal journal).

6 Troubleshooting Guide & Maintenance Hints

Chart 3 INCORRECT FLOW

A B C

NO FLOW LOW FLOW EXCESSIVE FLOW

1. Pump not receiving fluid 1. Flow control set too low 1. Flow control set too high Remedy: a Remedy: d Remedy: d

2. Pump drive motor not 2. Relief or unloading 2. Yoke actuating device operating valve set too low inoperative (variable displacement pumps) Remedy: e Remedy: d Remedy: e

3. Pump to drive coupling 3. Flow by-passing thru 3. RPM of pump drive sheared partially open valve motor incorrect Remedy: c Remedy: e or f Remedy: h

4. Pump drive motor turning 4. External leak in system 4. Improper size pump in wrong direction Remedy: b used for replacement Remedy: g Remedy: h

5. Directional control set in 5. Yoke actuating device wrong position inoperative (variable displacement pumps) Remedy: f Remedy: e

6. Entire flow passing 6. RPM of pump drive over relief valve motor incorrect Remedy: d Remedy: h

7. Damaged pump 7. Worn pump, valve, Remedy: c motor, cylinder or other component

8. Improperly assembled Remedy: e pump Remedy: e

Remedies: a. Any or all of the following: c. Check for damaged pump or pump f. Check position of manually operated drive; replace and align coupling. controls; check electrical circuit on Replace dirty filters; clean clogged solenoid operated controls; repair or inlet line; clean or replace reservoir d. Adjust. replace pilot pressure pump. breather vent; fill reservoir to proper level; overhaul or replace e. Overhaul or replace. g. Reverse rotation. supercharge pump. b. Tighten leaking connections. h. Replace with correct unit.

7 Troubleshooting Guide & Maintenance Hints

Chart 4 INCORRECT PRESSURE

A B C D

NO PRESSURE LOW PRESSURE ERRATIC PRESSURE EXCESSIVE PRESSURE

1. No flow 1. Pressure relief path 1. Air in fluid 1. Pressure reducing, exists Remedy: b relief or unloading Remedy: See Chart 3, valve misadjusted column A Remedy: See Chart 3, column A and B Remedy: d

2. Yoke actuating device 2. Pressure reducing valve 2. Worn relief valve inoperative (variable set too low Remedy: e displacement pumps) Remedy: d Remedy: e

3. Pressure reducing 3. Contamination in fluid 3. Pressure reducing, valve damaged Remedy: a relief or unloading Remedy: e valve worn or damaged Remedy: e 4. Damaged pump, motor 4. Accumulator defective or cylinder or has lost charge Remedy: e Remedy: c

5. Worn pump, motor or cylinder Remedy: e

Remedies: a. Replace dirty filters and system fluid. b. Tighten leaking connections (fill reservoir to proper level and bleed air from system).

8 Troubleshooting Guide & Maintenance Hints

Chart 5 FAULTY OPERATION

A B C D

NO MOVEMENT SLOW MOVEMENT ERRATIC MOVEMENT EXCESSIVE SPEED OR MOVEMENT

1. No flow or pressure 1. Low flow 1. Erratic pressure 1. Excessive flow Remedy: See Chart III Remedy: See Chart 3 Remedy: See Chart IV Remedy: See Chart 3

2. Limit or sequence 2. Fluid viscosity too high 2. Air in fluid 2. Feedback transducer device (mechanical, Remedy: a Remedy: See Chart I malfunctioning electrical or hydraulic) Remedy: e inoperative or misadjusted Remedy: e

3. Mechanical bind 3. Insufficient control 3. No lubrication of 3. Misadjusted or Remedy: b pressure for valves machine ways or malfunctioning servo Remedy: See Chart 4 linkage amplifier Remedy: See Chart 4 Remedy: c

4. No command signal 4. No lubrication of machine 4. Erratic command signal 4. Over-riding work load to servo amplifier ways or linkage Remedy: f Remedy: h Remedy: f Remedy: g

5. Inoperative or mis- 5. Misadjusted or malfunc- 5. Misadjusted or malfunc- adjusted servo amplifier tioning servo amplifier tioning servo amplifier Remedy: c Remedy: c Remedy: c

6. Inoperative servo valve 6. Sticking servo valve 6. Malfunctioning feedback transducer Remedy: c Remedy: c Remedy: e

7. Worn or damaged 7. Worn or damaged 7. Sticking servo valve cylinder or motor cylinder or motor Remedy: d Remedy: e Remedy: e

8. Worn or damaged cylinder or motor Remedy: e Remedies: a. Fluid may be too cold or should be c. Adjust, repair or replace. f. Repair command console or changed to clean fluid of correct interconnecting wires. viscosity. d. Clean and adjust or replace; check condition of system fluid and filters. g. Lubricate. b. Locate bind and repair. e. Overhaul or replace. h. Adjust, repair or replace counterbalance valve.

9 Quiet Hydraulics

Today, buyers are demanding quiet machines because of their concern Acoustic Isolation Reservoirs about meeting industry’s noise limits. The greatest sound level reductions are Reservoirs provide the means for Vickers is helping to meet this demand attained with the pump acoustically as releasing entrained bubbles. These by supplying quiet hydraulic well as mechanically isolated. This can come from sources other than the components. Sound levels of some requires that the pump be completely pump inlet and are usually present in pumps today, for example, are fifty enclosed in a non-porous shell weighing the fluid returning to the reservoir. It is percent lower than the same model at least 10 kg per square meter of important to note that low reservoir pumps of a few years ago. surface. No openings can be tolerated temperatures reduce the rate of and all joints must be sealed with bubble escape and may result in resilient gaskets or moldings. incomplete release. As pointed out Sound Advice earlier, high temperatures promote Grommets of rubber or other soft bubble formation. The best balance Producing quiet, hydraulically-actuated material should be used to close between these two alternatives is machines requires more than just the openings around piping and to prevent achieved by maintaining the use of quiet components. mechanical contact between the temperature of oil leaving the enclosure and piping. It must be reservoir in the range of 120 to Meeting the stringent sound-level emphasized that while mechanical 150F and the temperature of specifications of today’s industrial hydraulic isolation by itself can reduce noise, water-based fluids between 100 and systems and machines takes careful acoustic isolation can only be effective 120F. engineering. The pump should be when used in combination with considered first. It not only produces sound mechanical isolation. A simple reservoir has to be large directly but generates vibrations and fluid to effect complete bubble release. pulsations. These react with other machine By providing baffles to guide the fluid parts which produce more sound. Fluids through a circuitous path and by locating return and pump inlet lines The condition of the fluid being pumped as far apart as possible, a reservoir Pump Selection is also important in controlling sound. holding between two to three minutes Fluid viscosity, temperature and of maximum pump flow can be Pumps generate more acoustic energy vacuum by themselves have no effect adequate. per unit of hydraulic power by running at on sound levels. It is important to high speed rather than at low. For this control them, however, to prevent the reason, a pump should operate at 1200 formation of entrained air or vapor RPM whenever sound is critical. Below bubbles that can double sound levels, 3000 PSI, the trade-off between pressure and reduce pump life. and pump size for a given drive power has little effect on noise, so you are free A combination of high fluid to select any combination of these factors temperature and inlet vacuum that otherwise meet your needs. generates what are called cavitation bubbles. However, at low temperatures, a high viscosity fluid in a very long suction line can also Mechanical Isolation produce sufficient vacuum to cause To meet lower sound level limits, the cavitation. Important methods of pump should be mechanically isolated suppressing bubble formation include: from the rest of the machine using Using short runs or large diameter anti-vibration mountings. This also inlet lines; keeping the reservoir requires that all connections to the elevation close to or above that of the pumps be made with flexible hose. pump; using low pressure-drop inlet filters that signal when they are Flexible hose will often reduce noise even producing high vacuums and need where anti-vibration mountings are not changing; and, providing adequate used. It prevents vibrations from reaching fluid controls. These are all good other lines and components to keep them hydraulic practices that become from becoming sound sources. In long increasingly important where you lengths, this hose is, itself, a good sound must achieve low sound levels. generator so only short lengths should be used. For long runs, use solid pipes with short hoses at the ends. All long lines must be supported every meter or so, preferably with clamps providing vibration damping. Lines must not contact panels that are good sounding boards. Where they pass through such panels, allow sufficient clearance to prevent direct contact; never use bulkhead fittings in such cases.

10 Contamination Control

Contaminant in hydraulic systems is now recognized as the most frequent Control of Contamination cause of malfunction or failure of The following table prescribes hydraulic equipment. Dependent on the preventative measures relative to the nature, size and/or amount of different common types and causes of contaminant, it can cause: contamination. For additional information, request Vickers Guide to Systemic – Reduced component service life. Contamination Control, catalog 561.

– Machine malfunction, particularly when operating near maximum capacity. Fluid degradation by: – Risk of frequent breakdowns under Solid High Water Air the same conditions. Preventive Measures Contam. Temp. – Production rates below schedule. For Storage Drums: – Store in cool, dry location. – High product scrap rates and quality – Ensure that closures fully seal in the fluid. faults. – Wipe away any dirt and moisture from around the closure before loosening and emptying. – Use a portable filtration and transfer unit for Nature of Contaminant emptying and refilling. Contaminant can be either particle For Storage Tanks: contaminant or the product(s) of fluid – Install in cool, dry location. degradation. – Ensure that all covers and stop valves effectively seal in the fluid. – Keep filling lines clean; cap ends when not in use. Particle contaminant can be metal, rubber, plastic, dirt, dust, fibre, sand, – Use a portable filtration unit for filling and emptying. paint, etc.; several types may be present For Hydraulic Systems: at any time. It can enter the fluid at any time after the fresh clean fluid has been – Provide fluid filter(s) in location(s) that assure the produced by the fluid manufacturer. required protection. There is usually little likelihood that fresh – The ideal steady-state flow conditions through an fluid became contaminated during the off-line filter make this a must for most applications. refining and blending processes. – Whenever possible, use filters having element condition indicators. Fluid degradation results in: – Vented systems must be fitted with an air breather appropriate to the environment(s) in which the – Oxidation and/or the formation of machine is to be operated and the requirements of gummy deposits and sludge from the the system. combined effects of high – Fit strainers to pump inlet lines if there is risk of temperatures, air, water and particle large contaminant particles (i.e. string, rag, screws, contaminant. These can increase etc.) entering the lines. viscosity, cause gummy deposits to – Prevent air entering the system, particularly through coat moving parts, clog orifices and pump inlet lines. Ensure air-tight joints in any small passages, thus impairing sub-atmospheric zone or pump inlet lines. Also smooth mechanical movements and make sure that those lines and all return and drain form sludge. lines terminate below the minimum fluid level in the reservoir; pump inlet lines should be sufficiently – Unstable emulsions of poor lubricity below to prevent air entering through a vortex at formed when water accidently low fluid levels. emulsifies with oil. These impair smooth – Design for, and maintain, fluid temperatures at movements and promote wear. optimum levels for the application. Apply coolers if necessary. – Aeration or air bubbles in the fluid, – Locate or screen hydraulic systems away from high particularly at low pressures. In temperature sources (e.g. furnaces). excess, they cause noise in pumps and valves leading to erratic or – Assemble system in clean conditions using clean spongy machine movements, practices. premature wear and failure. – Pre-clean pipes and reservoir immediately before installation. Cap any ends that cannot immediately be connected to mating components (e.g. between shifts).

11 Fluid degradation by: Solid High Water Air Preventive Measures Contam. Temp. For Hydraulic Systems: – Remove protective caps only just before connecting mating components. – Use a portable filtration and transfer unit to fill the reservoir system. – Flush new systems, and those that have undergone major repairs, before starting up. Temporarily remove actuators and replace with flushing manifolds or valves. Servo valves and similar high precision units should also be replaced with flushing manifolds or valves for flushing operations. Make sure that actuators are clean internally before connecting to the system. – Make sure that air breathers and reservoir covers are at all times properly installed and tightly secured. – Stop any leakage of water into the system from coolers or other sources. Make a leak-tight repair. – By planned maintenance, ensure that clean filter elements are applied (or metallic elements cleaned when appropriate) when indicators or visual inspection shows this to be necessary. – Take fluid samples periodically and analyze to determine whether effects of particle contaminant, heat, water and air indicate need for more control of those factors or replacement of the fluid. – Whenever the reservoir is emptied, clean it out thoroughly and remove all residual contaminant. If necessary, restore protective paint or other finishes. On completion, cap all openings unless the system is to be refilled immediately.

12 Hints On Maintenance Of Hydraulic Fluid In The System

finer) can be used. It is important that Preparation of pipes, tubes and fittings Hydraulic Fluid Changes fluid be clean and free of all substances in this catalog should be referred to and Good maintenance procedures make it which will cause improper operation. followed. This will lower the possibility mandatory to keep the hydraulic fluid of premature failure due to clean. A daily, weekly or monthly log contamination of the system. should be kept on the hydraulic fluid Fluid Contamination – condition. Causes and Effects Adverse Operating Conditions No hard and fast rules can be Contamination From experience, we have found that established for changing the fluid machines used in a very dusty because of the great variety of operating A contaminated system can be the result atmosphere and in windy areas require conditions. However, we do know that of several factors; system design special components. For example, when filter elements are replaced inadequate, poor maintenance of the heavy duty breathers, chrome plated frequently, service life of a system system, poor housekeeping of the system piston rods, plus frequent changes of increases. Periodic testing of the fluid by and adverse operating conditions. the filter cartridges are also required. the supplier is recommended to confirm suitability for continued use and to System Design Inadequate establish the correct fluid and filter Effects of Contamination element replacement interval. – Reservoirs which cannot be cleaned. – Breathers that permit abrasives Contamination affects all types of hydraulic equipment adversely. Some of the considerations affecting inherent in the atmosphere to enter the system. Precision high tolerance parts are very hydraulic fluid are: operating susceptible to the effects of temperature, type of service, – Poor cylinder packing design (no contamination. Dirty fluid causes wear contamination levels, filtration, and the wiper to clean dirt from the piston which accelerates leakage and the chemical composition of the fluid. rod). development of heat in a system. Heat – Improper piston rod design (piston lowers the lubricity of a hydraulic fluid Fluid Recommendations rods with poor wear characteristic). and causes additional wear. – Improper valving (anti–cavitation The basic recommendations for fluid checks omitted from cylinder circuits If a hydraulic pump or motor should fail, are stipulated in the Hydraulic Fluid and with rapid drop characteristics). the system becomes contaminated. Remove the unit for repair. The Temperature Recommendations for – Failure to provide adequate filtration. Industrial Machinery in this catalog. reservoir must be drained, flushed, and The fluids recommended give the Poor Maintenance of the System cleaned. All hoses, lines, cylinders and assurance of adequate wear protection valves should be inspected for wear and excellent chemical stability under – Improper and unclean practices when and particles of the unit that failed. the most adverse operating conditions. adding fluid to the system. Flush all components of the complete – Failure to clean breathers. system to remove metallic particles. On mobile applications, the viscosity – Failure to change pitted cylinder rods grade of the fluid should be changed in Replace filter elements. Dispose of the and worn cylinder packings. fluid removed from the system and fill spring and autumn as is done with – Failure to use good cleanliness automotive engines. Hydrostatic the reservoir with clean hydraulic fluid. practices when changing system Install a new or rebuilt unit and start-up transmissions and control mechanisms components. may require a different viscosity fluid. the system. Allow the system to run for Fluid requirements are normally – Failure to change filter cartridges a period of time to verify normal outlined in the original equipment and/or filter at proper intervals. operation. Filter elements should be manufacturers operation and – Failure to purge debris from the changed after 40 or 50 hours of maintenance manuals. system after a pump failure. operation. This guarantees that the system is essentially clean and free of Poor Housekeeping of the Draining The System any residue of the failed unit. System A very good reference catalog on The system should be started and fluid Surgical cleanliness is not required, contamination is available titled Vickers heated before draining. This will lower however, ordinary clean practices Guide to Systemic Contamination the time it takes to drain the system and during assembly will pay off in Control. This catalog describes types allow impurities suspended in the fluid increased service life of the equipment. and sources for contamination, effects to be removed. It is desirable to remove of types and sizes of particles, all fluid from the system. Bleeding of Excessive and improper use of pipe specifying contamination levels, the fluid at the lowest point in the thread sealer on lines and gaskets in selecting a filter, locating a filter, design system will help in most cases. the system can cause pump failures. steps and worked examples of fluid This is especially true when a type of sampling analysis. Order catalog 561 Systems which have accumulated sealer is used that hardens. from your local Vickers representative. deposits that were not removed during draining must be flushed with a light Another source of contamination is viscosity fluid. The fluid should contain fittings, hoses and lines which are a rust inhibitor to protect metal surfaces received from a vendor uncapped. The against rust formation after draining. use of brazed or welded fittings, and unpickled steel plating can also When hydraulic fluid is added to contribute to the contamination. replenish the system, it should be pumped through a 25 micron filter. If such a filter is not available, a funnel with a fine wire screen (200 mesh or

13 Aeration

have a high sulphur content tend to Reservoir must be deep enough to Aeration accelerate “O” ring hardness. This is one prevent aeration. Causes of the principle reasons for keeping system operating temperatures down. Vortexing Fluid in the Reservoir Normal operating temperature of a The following are candidates for the If the fluid level in the reservoir is low system is 90 degrees above ambient. formation of air in a system. and the inlet demand is great, a vortex When operating temperatures are in – Leaking inlet lines. condition can develop which pulls air excess of this value, trouble may result. – Control valve “O” rings leaking. into the pump inlet. In a hydraulic Maximum operating temperatures should system, vortexing is normally the result – Shaft seal leakage. be checked at the pump outlet port. – Leaking cylinder packings caused of low fluid or poor reservoir design. by cavitating cylinders. Shaft Seal Leakage One of the best ways of curing a – Turbulence or sloshing in the vortex problem is to place an reservoir. Most vane pumps are internally drained. The shaft seal cavity is connected to the anti-cavitation plate over the outlet of – Vortexing fluid in the reservoir pump inlet. Excessively high inlet the reservoir. This is a common piece – Release of air suspended within vacuums can cause air leakage at the of sheet metal at lease 1/8 inch thick the fluid. shaft seal. The maximum vacuum set over and above the outlet opening. measured at the pump inlet should not This plate will allow flow into the outlet Effects exceed five inches of mercury. from a horizontal direction and effectively extends and enlarges the Aeration can be in many forms; large Shaft misalignment can increase the reservoir opening. This prevents the bubbles, foam or in various degrees of probability of air leakage past the shaft vortex condition from developing. suspension. It usually causes pump noise seal. Universal jointed couplings or (cavitation). Small bubbles cause extreme splined couplings can cause seal Release of Air Suspended in Fluid and rapid ring wear, with corresponding leakage if not properly aligned. Straight vane tip wear. Larger bubbles cause vanes (direct) coupling should never be used. There is considerable air suspended in to collapse and pound. This pounding cold hydraulic fluid. As the fluid warms, effect develops rippling in the ring and the The use of the wrong type of tools can air is released into the system. A ring will have a dull appearance. This is cause distortion or mutilation of a shaft reduction of fluid pressure will also more apparent on straight vane rings seal at installation. The outer diameter of release air out of suspension. A simple which are hardened cast iron. With the shaft should be lightly polished before relief valve poppet can create an orifice extreme aeration cases, the wear is so installation to remove any burrs or that increases velocity of the fluid and rapid that a ring and vanes can be roughness in the area of the shaft seal. lowers its pressure. The reduced destroyed within an hour. In many cases, a Shaft seals must be made of the correct pressure condition releases air out of large step will be worn in the ring contour material for a given application. A material suspension into the system. Relief valves at the pressure quadrant. When the step that is not compatible with system fluid can should be returned below the fluid level reaches a depth where the vane extends deteriorate and result in a leakage of the reservoir as far from the reservoir and locks, the vane and/or ring will break. problem. outlet as possible. This allows time for Also, the shaft can break where it enters the air released by the relief valve to be the rotor if the torque is great enough. Leaking Cylinder Packings removed before leaving the reservoir and Caused By Cavitating Cylinders entering the inlet area of the pump. Cures In some cases, special return line On applications where a rapid raise and configurations are needed, or air bleed Leaking Inlet Lines lower cycle is experienced, air can enter valves used, to remove air from the the system through a cylinder rod seal. system. – Pipe threaded fittings can be porous. Vacuums in excess of 20 inches of Use an approved type of pipe thread mercury have been recorded in systems A special baffle made of 60 mesh screen sealer on all pipe threads. without anti-cavitation check valves. This is can be installed into the reservoir. This – If the pump inlet flange surface is enough to force dirt particles past the shaft baffle should be positioned at a 30 angle rough, scored or mutilated, air leakage seal into the system with the air. An in the reservoir so that inlet oil is above the past the “O” ring seal can result. anti-cavitation check will allow flow from screen and outlet oil is below the screen. the reservoir to enter the rod area of the The top of the screen should be below the With any of the above defects, air can cylinder during a vacuum condition from reservoir fluid level far enough to prevent be pulled into the system. developing. This will lower the possibility of surface foam from coming in contact with fluid contamination through the rod seal of the screen. Surface foam can penetrate Control Valve “O” Rings Leaking a working cylinder. through the screen into the outlet area. “O” rings are used to seal against port The screen baffle will eliminate all leakage in many control valves. These Turbulence or Sloshing in the bubbles except the very small ones seals can be checked by applying heavy Reservoir from the fluid if designed properly. grease around the part to be checked. If Return lines, if improperly located, the noise stops, the trouble has been can cause turbulence and aeration. A located and repair can be initiated. Plexiglass window should be placed On systems which have been operating in the prototype reservoir to study flow at excessive high temperatures, the “O” conditions. Return lines emptying rings can harden and take a set. If this above the fluid level cause bubbles to occurs, air leakage can result. This is form in the system. Return lines true not only in a pump, but also in the should always be terminated below rest of the components of the system. the fluid level. Vehicle movement can Another factor enhancing air leakage is cause sloshing within the reservoir. the actual fluid composition. Fluids which 14 Leakage Control

4. Use a minimum number of fittings and Cost Of Leakage connectors. Use welded joints Mounting Plates Concern for safety at work and the wherever practical. When valve packages or subplates are rapidly increasing cost of oil makes bolted to mounting plates, the condition industry sensitive to leakage. 5. Use parallel thread connectors, tees of the plate is important to obtain a Leakage creates safety hazards, and elbows in place of tapered pipe satisfactory initial seal and prevent wastes costly oil, increases machine threads. extrusion and wear. Requirements are: down-time, decreases production rates, generates product spoilage and 6. Use manifolds instead of individual – Flat mounting surfaces increases replacement parts lines wherever possible. inventory. The cost of effective – Good sealing surface finish -64 leakage control is minor when 7. Specify proper bolt and plug torques micro-inches with no radial scratches compared to the long term costs of for expected peak pressures to leakage. prevent surface separation and static – High enough bolt preload to prevent seal nibbling. surface separation. Leak-Free Design 8. Stress good workmanship to avoid poorly assembled fittings and Preventing Seal Hydraulic systems do not need to leak. connectors. Today’s designer must create a more Deterioration leak resistant system, where static seal leakage should not occur and Reducing Dynamic Seal Premature deterioration of the seal can dynamic seal leakage will be result from other factors. A primary controlled. Before presenting some Wear factor is excessive fluid temperature. A design practices proved effective in good guide is that seal life is halved by Most dynamic seals are well designed every 20 F. rise. The cure: Incorporate stopping leaks, we should consider the and will provide long, relatively sources of most leaks. sufficient heat exchangers to keep fluid leak-free service if given reasonable temperatures below 150 F. chance. Four things a designer can do to extend the life of dynamic seals are: Another factor may be compatibility of Cause Of Leaks the fluid with the seal material where 1. Eliminate side loads on cylinder rod special fluids are used. If a doubt arises, Almost all hydraulic system leaks and drive shaft seals. contact your Vickers representative. The occurring after extended service result following brief review of seal materials from three conditions: 2. Protect cylinder rods from abrasive may be helpful. dirt with scrapers, shields or rubber – Loosening of fittings and connectors gaiters. Nitrile (Buna N) is the most widely used by shock and vibration and best all around elastomer for 3. Provide the requisite filtration and petroleum (mineral) oils, fuel and – Wear of dynamic seals and mating easily cleaned reservoirs to prevent fire-resistant fluids – with the exception parts especially in hydraulic cylinders dirt build-up in the oil. of phosphate esters. – Deterioration of the elastomer 4. Keep cylinder rod and shaft speeds Fluoroelastomer (Viton or Fluorel) because of elevated fluid as low as possible. temperatures or an incompatibility with costs more than Nitrile, can be used the hydraulic fluid instead of Nitrile but has the added advantage of longer life when fluid Requirements For temperatures consistently run above 150 F. It can be used with phosphate Combatting Shock And Static Seals ester fluids (except Skydrol). Vibration A static seal retains fluid between rigid, stationary surfaces. The seal must be Polyurethane shows extrusion and Many things can be done to minimize compressed as with a gasket or abrasion resistance superior to Nitrile leakage from loose fittings and deformed as with an “O” ring, to flow in petroleum oils, fuel and silicate connectors subject to shock and into the microcrevices in the mating esters, but deteriorates if vibration: surface and also raise the seal’s contaminated with hot water. internal stress level higher than the 1. Support all pipe lines with damped pressure to be sealed. When parts are Refer to “Stop Leaks” bulletin 394 for mountings to absorb both shock and not rigid enough or bolt preload is not more comprehensive coverage of vibration. high enough, the mating surfaces will leakage control. separate under the action of fluid 2. Reduce shock with low-shock valves pressure, creating clearances of or accumulators. enlarging those that might exist because the sealing surfaces were not 3. Use pressure controls with low initially flat enough. With movement of override and strategically placed to mating surfaces, the static seal protect all parts of the system. becomes a dynamic seal. Rough surfaces will wear the seal and changing clearances nibble seal edges.

15 Hydraulic Fluid And Temperature Recommendations For Industrial Machinery

Unit Type Viscosity Anti-wear Characteristicts Inline Piston Viscosity (Pumps & Motors) Grades: 32-68 cSt (150-315 SUS) @ 40C. (104F) Running: 13-54 cSt (70-250 SUS) At Start Up: 220 cSt (1000 SUS) Max. Antiwear typeyy hydraulic oils such as: Angle Piston Viscosity automotive crankcase oils having API Vane (Except MHT) Grades: 32-68 cSt (150-315 SUS) @ 40C. (104F) letter designations “SE”, “SF”, “SG”, or Gear Running: 13-54 cSt (70-250 SUS) “SH” per SAE J183 (Pumps & Motors) At Start Up: 860 cSt (4000 SUS) Max. Viscosity MHT (High Torque/ Grades: 32-68 cSt (150-315 SUS) @ 40C. (104F) Low Speed Running: 13-54 cSt (70-250 SUS) Vane Motors At Start Up: 110 cSt (500 SUS) Max. cSt: Centistokes SUS:Saybolt Universal Seconds

Adhere to the oil recommendations for MHT units rather than the pumps involved.

Viscosity Grades are the standard viscosity grades listed in ASTM D-2422 titled “Viscosity System for Industrial Fluid Lubricants”, but any intermediate viscosity is acceptable.

Selection Of Viscosity Grades Use the following tabulation to The SAE 10W grades fall between determine the temperature extremes the 32 cSt (150 SUS) and 46 cSt between which the viscosity grades (215 SUS) grades and the SAE can be used to remain within Vickers 20–20W approximates the 68 cSt start–up and running viscosity range (315 SUS) grade. recommendations. Viscosity Start Up Start Up Start Up Running Running Grade 860 cSt 220 cSt 110 cSt 54 cSt 13 cSt 40C (104F) (4000 SUS) (1000 SUS) (500 SUS) (250 SUS) Max. (70 SUS) Min. 32 cSt (150 SUS) –12C (11F) 6C (42F) 14C (58F) 27C (80F) 62C (143F) 46 cSt (215 SUS) –6C (22F) 12C (54F) 22C (72F) 34C (94F) 71C (159F) 68 cSt (315 SUS) 0C (32F) 19C (66F) 29C (84F) 42C (108F) 81C (177F)

Some of the factors especially important Two specific types of oil meet the General Data in the selection of oil for use in an requirements of modern industrial industrial hydraulic system are: hydraulic systems: Oil in hydraulic systems performs the dual function of lubrication and 1. The oil must contain the necessary 1. Antiwear type industrial hydraulic oils. transmission of power. It constitutes a additives to ensure high antiwear A new generation of industrial vital factor in a hydraulic system, and characteristics. Not all hydraulic oils hydraulic oils containing adequate careful selection should be made with contain these in sufficient amounts. quantities of antiwear compound is the assistance of a reputable supplier. recommended by VIckers for general Proper selection of oil assures 2. The oil must have proper viscosity to hydraulic service. satisfactory life and operation of the maintain adequate sealing and system components with particular lubricating quality at the expected emphasis on hydraulic pumps and operating temperature of the motors. Generally, oil selected for use hydraulic system. with pumps and motors are acceptable for use with valves. Critical servo 3. The oil must have rust and oxidation valves may need special consideration. inhibitors for satisfactory system operation.

16 Hydraulic Fluid And Temperature Recommendations For Industrial Machinery

These oils are generally developed maximum and minimum viscosity ranges and evaluated on the basis of pump of the oil at start-up and during running be Cleanliness wear tests such as the Vickers maintained. (See chart) Very high Thorough precautions should always be 35VQ25A and ASTM D-2882. These viscosities at start-up temperatures can observed to ensure that the hydraulic oils offer superior protection against cause noise and cavitational damage to system is clean. pump and motor wear and the pumps. Continuous operation at advantage of long service life. In moderately high viscosities will tend to hold 1. Clean (flush) entire system to remove addition, they provide good air in suspension in the oil as well as paint, metal chips, welding shot, lint, demulsibility as well as protection generate higher operating temperatures. etc. against rust. This can cause noise and early failure of pumps, motors and erosion of valves. Low 2. Filter each change of oil to prevent 2. Automotive type crankcase oils viscosities result in decreased system introduction of contaminant into the having API letter designation “SE”, efficiency and impairment of dynamic system. “SF”, “SG”, “SH”, per SAE J183. lubrication which causes wear. 3. Provide continuous oil filtration to remove sludge and products of wear The above classes of oils in the Choose the proper oil viscosity for your and corrosion generated during the 10W and 20-20W SAE viscosity particular system so that over the entire life of the system. ranges are for severe hydraulic temperature range encountered, the service where there is little or no start-up viscosity and the running 4. Provide continuous protection of water present. The only adverse viscosity range shown in the chart is system from entry of airborne effect is that the “detergent” met. This is important, and assurance contamination by proper filtration of additive tends to hold water in a should be obtained from your oil air through breathers. tight emulsion and prevents supplier that the viscosity of the oil being 5. During usage, proper oil filling of separation of water, even on long used will not be less than the minimum reservoir and servicing of filters, time standing. recommended at maximum oil breathers, reservoirs, etc. cannot be temperature encountered. over emphasized. Automotive type crankcase oils generally exhibit poorer shear stability A number of antiwear hydraulic oils which could result in some loss of containing polymeric thickeners (V.I. Sound Level viscosity during their service life. improvers) are available and are used for More shear stable multiple viscosity low temperature application. The Noise can be an indication of system industrial grade hydraulic fluids will temporary and permanent viscosity loss of problems. Fluid selection and the provide improved viscosity control. some of these oils at operating condition of that fluid in service will temperature may adversely affect the life affect the noise levels of your systems. Over the years, Vickers hydraulic oil and performance of components. Be recommendations have been based on certain you know the extent of loss of Some of the major factors affecting the oils that: (1) provide adequate wear viscosity (shear stability) of polymer fluid conditions that cause the loudest protection, (2) have proper viscosity, and containing oils under hydraulic service noises in a hydraulic system are: (3) are sufficiently stable to withstand the before using them so that you do not chemical, thermal and mechanical stresses operate below the recommended minimum 1. Very high viscosities at start-up of severe hydraulic service. There are viscosity. The selection of an oil with good temperatures can cause pump noises automotive crankcase oils that are outside shear stability, is recommended for low due to cavitation. of the API SE, SF, SG and SH classes temperature applications. that meet the above basis of 2. Running with moderately high recommendation. viscosity fluid will impede the release of entrained air. The fluid will not be With these oils, it is highly desirable to Temperature completely purged of such air in the have acceptable data from pump wear time it remains in the reservoir before To obtain optimum service life from recycling through the system. tests (35VQ25A and ASTM-D-2882). In both the oil and the hydraulic system, exceptional cases where the requirements operate between 49C (120F) and of speed, pressure, temperature and 54C (130F). The maximum oil ambient conditions exceed the temperature normally recommended recommendations for industrial machinery, is 66C (150F). please refer to the oil recommendations. These fluids must also pass the Vickers MHT motors are permitted to operate at 35VQ25 pump test. higher temperatures, but this is permissible by meeting special application requirements. For this Viscosity service, oils should have antiwear characteristics required to pass pump Viscosity is the measure of the fluid’s test on page 20. Pumps can be resistance to flow. The selection of a approved to operate MHT motors at hydraulic oil of specific viscosity range these higher temperatures. Contact your must be based on the needs of the Vickers representative for system, limitations of critical components, recommendations. or proper performance of specific types of units. Vickers recommends that certain

17 3. Aerated fluid can be caused by Water-Glycol Fluids ingestion of air through the pipe joints Water Based Fluids of inlet lines, high velocity discharge General Data Water-glycol fire-resistant fluids are lines, cylinder rod packings, or by typically water and diethylene glycol fluid discharging above the fluid level To assure an effective emulsion or mixtures. They have approximately 40% in the reservoir. Air in the fluid will solution, the water should not have water content. cause abnormal noise and wear in excessive hardness or have an acid Oil-In-Water Fluids your system. nature, and it should be distilled or deionized with less than 300 parts per Oil-in-water fluids are emulsions of oil 4. Contamination fluids can cause million hardness. and water. When preparing these excessive wear of internal pump mixtures, the soluble oil should always parts which may result in increased Hard water containing excessive mineral be added to the water while maintaining sound levels. content, such as calcium and iron, may good fluid agitation. The water should cause deposits in the hydraulic system never be added to the soluble oil. Do not 5. Systems using water based fluids or result in additive separation or mix soluble oil brands. are susceptible to noise created by emulsion breaking. vaporization of the fluid if excessive Filters vacuums and temperatures are Proper maintenance of water containing encountered. fluids requires periodic testing for pH, oil Many Vickers standard indicating type and water concentrations. The pH inlet filters and return line filters are should be maintained at 8.0-9.5 in approved with water-based fluid types. Fire Resistant Fluids accordance with the supplier’s recommendation. If the pH number A reduction of predicted life of hydraulic Hydraulic systems using fire resistant exceeds these limits, discard the fluid. components should be expected when fluids require special engineering Always use a premixed fluid to replenish using water-based fluid types. considerations. For applications using the system. The recommended storage fire resistant fluids, consult Vickers or operating temperature range of water Synthetic Fluid Type Guide to Alternative Fluids, Bulletin containing fluids is 4C (39F) to 49C 579, for the specific component being (120F), unless otherwise specified by Phosphate Ester used or contact your local Vickers the fluid supplier. representative for assistance. Phosphate ester type fluids are Types Of Water Based manufactured from chemically produced Proper design, operation and esters. These types of fluids require maintenance of fluid power systems is Fluids fluorocarbon seals. Consult your fluid of paramount importance to obtain the supplier for the types of seals which are optimum performance of fire resistant Invert Emulsions compatible. fluids such as synthetics, water glycol Invert emulsions are inverted Environmental Hydraulic Oil and water-in-oil emulsion types. water-in-oil emulsions consisting of a continuous oil phase surrounding finely If you have equipment that operates in Additionally, you should consult your fluid divided water droplets that are uniformly environmentally sensitive areas, you may supplier for specific fluid maintenance dispersed throughout the mixture. consider use of more environmentally and application data on their fluid. aware fluids. These fluids perform well in our hydraulic systems but may require extra caution in order not to exceed their performance capabilities.

18 Hydraulic Fluid And Temperature Recommendations For Mobile Hydraulic Systems

The oil in a hydraulic system serves as index. The viscosity index of hydraulic Antiwear Hydraulic Oil the power transmission medium. It is system oil should not be less than 90. also the system’s lubricant and coolant. Multiple viscosity oils, such as SAE These oils are produced by all major oil The selection of proper oil is a 10W-30, incorporate additives to improve suppliers and should consist of good requirement for satisfactory system viscosity index (polymer thickened). These quality base stocks compounded with performance and life. oils should have a minimum viscosity index antiwear, antioxidation, antifoam and of 120. Oils of this type generally exhibit antirust additives. These may be In most cases, use of these both a temporary and permanent decrease petroleum, vegetable or synthetic base oil. recommendations will lead to selection of in viscosity due to oil shear encountered in a suitable oil. However, due to the the operating hydraulic system. The actual Due to the large number of different complex nature of oil formulation, the viscosity can, therefore, be far less in the antiwear hydraulic oils, it is impossible variety of oils available and peculiarities of operating hydraulic system than what is for Vickers to test its products with all of individual hydraulic applications, there will shown in normal oil data. Accordingly, the available fluids. Because of this, an be rare instances where an oil selected when such oils are selected, it is evaluation procedure was developed for on the basis of these recommendations necessary to use those with high shear fluid suppliers to establish the suitability may yield unsatisfactory results. Vickers stability to insure that viscosity remains of their products for use in Vickers cannot be responsible for such within recommended limits while in service. components. Refer to “Pump Test exceptions. In this respect, the customer Procedure For Evaluation Of Antiwear is encouraged to consult his Vickers Chemical Stability Hydraulic Fluids For Mobile Systems”, representative or a reputable oil company page 20, for details of the 35VQ25 test when selecting an oil. Oxidation and thermal stability are procedure. It is the responsibility of your essential characteristics of oils for mobile oil supplier to assure that their fluids hydraulic systems. The combination of meet Vickers requirements. Important Factors In base stocks and additives should be stable during the expected lifetime of the Environmental Hydraulic Oil Selecting An Oil oil when exposed to the environment of these systems. If you have equipment that operates in Additives environmentally sensitive areas, you may consider use of more Hydraulic fluids contain a number of Suitable Types Of Oil envionmentally aware fluids. These additive agents which materially improve fluids perform well in our hydraulic various characteristics of oil for systems but may require extra caution in hydraulic systems. These additives are Crankcase Oil order not to exceed their performance selected to reduce wear, increase Oil having an API letter designation SE, capabilities. For further clarification, chemical stability, inhibit corrosion and refer to Vickers Guide to Alternative depress the pour point. SF, SG or SH per SAE J183. Note that one oil may meet one or more of these Fluids, Bulletin 579. designations. Antiwear Other Oils Pump performance and reliability are Certain other types of petroleum oil are directly affected by the antiwear additive suitable if they meet the following formulation contained in the oil. Oils provisions: providing a high level of antiwear protection are recommended for 1. Contain the type and content of optimum performance and long life. antiwear additives found in the above designated crankcase and antiwear Viscosity hydraulic oils, and have passed the pump tests. Viscosity is the measure of the fluid’s resistance to flow. The oil selected must 2. Have sufficient chemical stability for have proper viscosity to maintain an mobile hydraulic system service. adequate lubricating film at system operating temperature. 3. Meet the viscosity requirements shown in the following tables. In addition to dynamic lubricating properties, oil must have sufficient body to provide an adequate sealing effect between working parts of pumps, valves, clylinders and motors, but not enough to cause pump cavitation or sluggish valve action. Optimum operating viscosity of the oil should be between 16 cSt (80 SUS) and 40 cSt (180 SUS).

“Viscosity Index” reflects the way viscosity changes with temperature. The smaller the viscosity change, the higher the viscosity 19 Oil Viscosity Recommendations

Oil Viscosity Recommendations

Crankcase Oils Antiwear Hydraulic Oils

Hydraulic System Hydraulic System Operating Tem- SAE Viscosity Operating Tem- ISO Viscosity perature Range1 Designation perature Range1 Grade –23C to 54C 5W, 5W-20, –21C to 60C 22 (–10F to 130F) 5W-30 (–5F to 140F) –18C to 83C 10W –15C to 77C 32 (0F to 180F) (5F to 170F) –18C to 99C 10W-30, –9C to 88C 46 (0F to 210F) 10W-40 (15F to 190F) 10C to 99C 20-20W –1C to 99C 68 (50F to 210F) (30F to 210F)

1 Temperatures shown are cold (ambient) start-up to maximum operating. During cold start-up, avoid high-speed operation of hydraulic components until the system is warmed up to provide adequate lubrication.

20 Pump Test Procedure For Evaluation Of Antiwear Fluids For Mobile Systems

3. Increase pressure to 205-210 bar Test Pump gage (2975-3025 psig). When Test Circuit temperature stabilizes at 90-96C 35VQ25A-11*20 (Cartridge Kit P/N 1 413421) (195-205F), record operating parameters, including flow. Terminate test if flow is below 136 L/min (36 10 ″ Test Conditions gpm) after five hours of operation. 2 Line Size With production tolerances, low flow 9 5 Speed: 2350-2400 rpm sometimes occurs while pumping light fluids. This condition tends to Outlet Pressure: 205-210 bar gage M (2975-3025 psig) increase the wear rate. 8 Inlet Pressure: 0-.15 bar gage 6 3 2 (0-2 psig) with flooded inlet Test Duration Inlet Temperature: 90-96C (195-205F) Continue operation of the unit for 50 hours total (including break-in time), periodically monitoring operation Operating Mode parameters. 7 4 Steady-state pressure at above rated conditions for 50 hours. Terminate test if Description of Components flow degradation exceeds 7.5 L/min Number Of Cartridges (2 gpm) prior to the completion of the 1. Reservoir (50 gallons minimum; Evaluation requires a minimum of three 50-hour test. Such terminations are not elevated above pump centerline to pump cartridges. The fluid should not be considered to be failures since this flow provide gravity feed) degradation can be due to causes other changed during the total 150-hour test period. than excessive wear, such as erosion on 2. Temperature gage or thermocouple the side plates resulting from insufficient inlet pressure. Accept/Reject Guidelines 3. Inlet pressure gage Initial Fluid Condition 1. Total weight loss of all vanes from 4. Pump: 35VQ25A-11*20 (cartridge kit individual cartridge tested should be P/N 413421) Water Content: .075% maximum less than 15 mg (not including Contamination Level: ISO Code intravanes). 5. Electric motor (125 HP) 18/16/14 or better particle count. 2. Weight loss of ring from individual 6. Outlet pressure gage Alternatively, 30 cartridge tested should be less than mg/liter maximum 75 mg. 7. Pressure relief valve gravimetric con- tamination (using 3. Regardless of weight loss 8. Filter (10 micrometer nominal) filter membrane measurements, the pump parts, of 0.8 micrometer especially the rings, should not have 9. Cooler porosity). evidence of unusual wear or stress in contact areas. There may be 10. Flow meter instances when unsatisfactory performance is indicated even though Pump Break-In the weight loss is low; for example, galling or excessive burning would Procedure not show as excessive weight loss 1. Increase pump speed to test level but would be unacceptable. and apply 70 bar gage (1000 psig) outlet pressure. When inlet When any one cartridge out of three temperature of approximately 50C fails for any reason, two more (125F) is achieved, maintain it for cartridges should be tested. In this case, 1 elapsed time of /2 hour at pressure. four of the five tested cartridges must meet the above accept/reject guidelines. 2. Increase pressure to 140 bar gage (2000 psig). When inlet temperature This procedure is offered only as a fluid of approximately 80C (175F) is screening method. Successful achieved, maintain it for elapsed time completion of this test does not 1 of /2 hour at pressure. constitute endorsement or approval of fluids by Vickers.

21 Acceptable Rings Unacceptable Rings

22 Oil Flow Velocity In Tubing

Oil Flow Capacity Of Tubing Figures in the chart are USgpm flow capacities of tubing, and were calculated from the formula: GPM = V A B .3208, in which V = velocity of flow in feet per second, and A is inside square inch area of tube.

Figures in Body of Chart are USgpm Flows Tube Wall 2 4 10 15 20 30 O.D. Thick. Ft/Sec Ft/Sec Ft/Sec Ft/Sec Ft/Sec Ft/Sec .035 .905 1.81 4.52 6.79 9.05 13.6 .042 .847 1.63 4.23 6.35 6.47 12.7 .049 .791 1.58 3.95 5.93 7.91 11.9 1/2 .058 .722 1.44 3.61 5.41 7.22 10.8 .065 .670 1.34 3.35 5.03 6.70 10.1 .072 .620 1.24 3.10 4.65 6.20 9.30 .083 .546 1.09 2.73 4.09 5.46 8.16 .035 1.51 3.01 7.54 11.3 15.1 22.6 .042 1.43 2.85 7.16 10.7 14.3 21.4 .049 1.36 2.72 6.80 10.2 13.6 20.4 .058 1.27 2.54 6.34 9.51 12.7 19.0 5/8 .065 1.20 2.40 6.00 9.00 12.0 18.0 .072 1.13 2.26 5.66 8.49 11.3 17.0 .083 1.03 2.06 5.16 7.73 10.3 15.5 .095 .926 1.85 4.63 6.95 9.26 13.9 .049 2.08 4.17 10.4 15.6 20.8 31.2 .058 1.97 3.93 14.8 9.84 19.7 29.6 .065 1.88 3.76 14.1 9.41 18.8 28.2 3/4 .072 1.75 3.51 13.2 8.77 17.5 26.4 .083 1.67 3.34 12.5 8.35 16.7 25.0 .095 1.53 3.07 11.5 7.67 15.3 23.0 .109 1.39 2.77 10.4 6.93 13.9 20.8 .049 2.95 5.91 14.8 22.2 29.5 44.3 .058 2.82 5.64 14.1 21.1 28.2 42.3 .065 2.72 5.43 13.6 20.4 27.2 40.7 7/8 .072 2.62 5.23 13.1 19.6 26.2 39.2 .083 2.46 4.92 12.3 18.5 24.6 36.9 .095 2.30 4.60 11.5 17.2 23.0 34.4 .109 2.11 4.22 10.6 15.8 21.1 31.7 .049 3.98 7.96 19.9 29.9 39.8 59.7 .058 3.82 7.65 19.1 28.7 38.2 57.4 .065 3.70 7.41 18.5 27.8 37.0 55.6 .072 3.59 7.17 17.9 26.9 35.9 53.8 1 .083 3.40 6.81 17.0 25.5 34.0 51.1 .095 3.21 6.42 16.1 24.1 32.1 48.2 .109 3.00 6.00 15.0 22.4 29.9 44.9 .120 2.83 5.65 14.1 21.2 28.3 42.4

23 Pipe Sizes And Pressure Ratings

Figures in Body of Chart are USgpm Flows Tube Wall 2 4 10 15 20 30 O.D. Thick. Ft/Sec Ft/Sec Ft/Sec Ft/Sec Ft/Sec Ft/Sec .049 6.50 13.0 32.5 48.7 64.9 97.4 .058 6.29 12.6 31.5 47.2 62.9 94.4 .065 6.14 12.3 30.7 46.0 61.4 92.1 .072 6.00 12.0 30.0 44.9 59.9 89.8 1-1/4 .083 5.75 11.5 28.8 43.1 57.5 86.3 .095 5.50 11.0 27.5 41.2 55.0 82.5 .109 5.21 10.4 26.1 39.1 52.1 78.2 .120 5.00 10.0 25.0 37.4 50.0 74.9 .065 9.19 18.4 45.9 68.9 91.9 138 .072 9.00 18.0 45.0 67.5 90.0 135 .083 8.71 17.4 43.5 65.3 87.1 131 1-1/2 .095 8.40 16.8 42.0 63.0 84.0 126 .109 8.04 16.1 40.2 60.3 80.4 121 .120 7.77 15.5 38.8 58.3 77.7 117 .065 12.8 25.7 64.2 96.3 128 193 .072 12.6 25.2 63.1 94.7 126 189 .083 12.3 24.6 61.4 92.1 123 184 1-3/4 .095 11.9 23.8 59.6 89.3 119 179 .109 11.5 23.0 57.4 86.1 115 172 .120 11.2 22.3 55.8 83.7 112 167 .134 10.7 21.5 53.7 80.6 107 161 .065 17.1 34.2 85.6 128 171 257 .072 16.9 33.7 84.3 126 169 253 .083 16.5 32.9 82.3 123 165 247 2 .095 16.0 32.1 80.2 120 160 240 .109 15.5 31.1 77.7 117 155 233 .120 15.2 30.3 75.8 114 152 227 .134 14.7 29.4 73.4 110 147 220

Pipe Sizes And Pressure Ratings

Nominal Outside Number Length Schedule 40 Schedule 80 Schedule 160 Double Pipe Diameter of of (Standard) (Extra Heavy) Extra Heavy Size of Pipe ThreThreads d Effective Pipe Burst Pipe Burst Pipe Burst Pipe Burst in. in. Per Inch Threads ID-in. Pres. ID-in. Pres. ID-in. Pres. ID-in. Pres. in. PSI PSI PSI PSI 1/8 0.405 27 0.26 – – – – – – – – 1/4 0.540 18 0.40 .364 16,000 .302 22,000 – – – – 3/8 0.675 18 0.41 .493 13,500 .423 19,000 – – – – 1/2 0.840 14 0.53 .622 13,200 .546 17,500 .466 21,000 .252 35,000 3/4 1.050 14 0.55 .824 11,000 .742 15,000 .614 21,000 .434 30,000 1 1.315 11-1/2 0.68 1.049 10,000 .957 13,600 .815 19,000 .599 27,000 1-1/4 1.660 11-1/2 0.71 1.380 8,400 1.278 11,500 1.160 15,000 .896 23,000 1-1/2 1.900 11-1/2 0.72 1.610 7,600 1.500 10,500 1.338 14,800 1.100 21,000 2 2.375 11-1/2 0.76 2.067 6,500 1.939 9,100 1.689 14,500 1.503 19,000 2-1/2 2.875 8 1.14 2.469 7,000 2.323 9,600 2.125 13,000 1.771 18,000 3 3.500 8 1.20 3.068 6,100 2.900 8,500 2.624 12,500 – –

24 Preparation Of Pipes, Tubes, And Fittings Before Installation In A Hydraulic System

General Requirements – Threaded fittings should be – Rinse parts in hot water inspected to prevent metal slivers When installing the various iron and from the threads getting into the – Place in tank No. 3. The solution in steel pipes, tubes, and fittings of a hydraulic system. this tank should contain antirust hydraulic system, it is necessary that compounds as recommended by the they be absolutely clean, free from – Before filling the system with manufacturer. Usually the parts being scale, and all kinds of foreign matter. hydraulic oil, be sure that the treated should be left to dry with To attain this end, the following steps hydraulic fluid is as specified and antirust solution remaining on them. should be taken: that it is clean. DO NOT use cloth strainers or fluid that has been If pieces are stored for any period of – Tubing, pipes and fittings should be stored in contaminated containers. time, ends of the pipes should be brushed with boiler tube wire brush plugged to prevent the entrance of or cleaned with commercial pipe – Use at least a No. 120 mesh screen foreign matter. Do not use rags or cleaning apparatus. The inside edge when filling the reservoir. Use of a waste as they will deposit lint on the of tubing and pipe should be reamed Vickers clean cart, porta filtering inside of the tube or pipe. after cutting to remove burrs. Also and transfer unit, is recommended. Immediately before using pipes, remove burrs from outside edge. Operate the system for a short time tubes and fittings should be to eliminate air in the lines. Add thoroughly flushed with suitable – Short pieces of pipe and tubing and hydraulic fluid if necessary. degreasing solution. steel fittings should be sandblasted to remove rust and scale. – Safety precautions. Dangerous Sandblasting is a sure and efficient chemicals are used in the cleaning method for short straight pieces and and pickling operations to be fittings. Sandblasting should not be described. They should be kept only used however, if there is the in the proper containers and slightest possibility that particles of handled with extreme care. sand will remain in blind holes or pockets in the work after flushing. Pickling Process – In the case of longer pieces of pipe or short pieces bent to complex shapes – Thoroughly degrease parts in where is is not practical to sandblast, the degreaser, using a recommended parts should be pickled in a suitable vapor degreasing solvent. solution until all rust and scale is removed. Preparation for pickling – Tank No. 1 Solution. Use a requires thorough degreasing in a commercially available derusting recommended vapor degreasing solvent. compound in solution as recommended by the manufacturer. – Neutralize pickling solution. The solution should not be used at a temperature exceeding that – Rinse parts and prepare for storage. recommended by the manufacturer, otherwise the inhibitor will – Tubing must not be welded, brazed, evaporate and leave a straight acid or silver soldered after assembly as solution. The length of time the part proper cleaning is impossible in will be immersed in this solution will such cases. It must be accurately depend upon the temperature of the bent and fitted so that it will not be solution and the amount of rust or necessary to spring it into place. scale which must be removed. The operator must use good judgement – If flange connections are used, on this point. flanges must fit squarely on the mounting faces and be secured with – After pickling, rinse parts in cold screws of the correct length. Screws running water and immerse in tank or stud-nuts must be drawn up No. 2. The solution in this tank evenly to avoid distortion in the should be a neutralizer mixed with valve or pump body. water in a proportion recommended by the manufacturer. This solution – Be sure that all openings into the should be used at recommended hydraulic system are properly temperatures and the parts should covered to keep out dirt and metal remain immersed in the solution for slivers when work such as drilling, the period of time recommended by tapping, welding, or brazing is being the manufacturer. done on or near the unit.

25 ISO/ANSI Basic Symbols For Fluid Power Equipment And Systems

Lines Pumps

Line, Working Hydraulic Pump (Main) Fixed Displacement Heater Line, Pilot (For Control) Line, Liquid Drain Variable Hydraulic Cooler Displacement Flow, Direction of Pneumatic

Motors and Cylinders Temperature Lines Crossing or Controller Hydraulic Fixed Displacement Lines Joining Filter, Strainer

Line With Fixed Restriction Variable Displacement Line, Flexible Pressure Switch

Station, Testing, Cylinder, Single  Measurement or Acting Power Take-Off Cylinder, Double Acting Pressure Indicator Variable Component (run arrow through Single End Rod symbol at 45 Double End Rod Temperature Indicator Adjustable Cushion Pressure Compen- Advance Only sated Units (arrow Component parallel to short side Differential Enclosure of symbol) Piston Direction of Shaft Rotation (assume Miscellaneous Units arrow on near side Temperature Cause of shaft or Effect Electric Motor M Vented Reservoir Pressurized Accumulator, Spring Methods of Operation Line, To Reservoir Loaded Above Fluid Level Spring

Below Fluid Level Manual Accumulator, Gas Charged Vented Manifold Push Button

26 Flow Control, Push-Pull Lever Adjustable Definition Of Functions (temperature and pressure Function Definition Pedal or Treadle compensated Intensified Pressure Pressure in excess of supply pressure which is Two Position induced by a Mechanical Two Connection booster or intensifier. Two Position Supply Pressure Power-actuating Detent Three Connection fluid. Charging Pressure Pump-inlet Pressure Two Position pressure that is higher than Compensated Four Connection atmospheric Solenoid, Single pressure. Winding Three Position Reduced Pressure Auxiliary pressure Four Connection which is lower than supply Servo Control pressure. Two Position In Transition Pilot Pressure Control-actuating pressure. Pilot Pressure Valves Capable Of Metered Flow Fluid at controlled Remote Supply Infinite Positioning flow rate, other (horizontal bars than pump Internal Supply indicate infinite delivery. positioning ability) Exhaust Return of power and control fluid to reservoir. Valves Note Intake Sub-atmospheric pressure, usually Additional symbols are shown in on intake side of Check Vickers Circuitool booklet available for pump. a nominal charge. Ask for circuitool Drain Return of leakage On–Off template kit 352. fluid to reservoir. (manual shut-off) Inactive Fluid which is Color Code For Fluid within the circuit, but which does Power Schematic not serve a Pressure Relief Drawings functional purpose during Function Color the phase being represented. Intensified Pressure. . Black Supply...... Red Pressure Reducing Charging Pressure. . . Intermittent Red Reduced Pressure. . . . Intermittent Red Pilot Pressure...... Intermittent Red Metered Flow...... Yellow Flow Control, Exhaust...... Blue Adjustable– Intake...... Green Non-Compensated Drain...... Green Inactive...... Blank

27 Conversion Factors

To convert Into Multiply by Into To convert Divide by Unit Symbol Unit Symbol Factor Atmospheres Atm bar bar 1.013250 BTU/hour Btu/h kilowatts kW 0.293071  10–3 cubic centimeters cm3 liters 1 0.001 cubic centimeters cm3 milliliters ml 1.0 cubic feet ft3 cubic meters m3 0.0283168 cubic feet ft3 liters l 28.3161 cubic inches in3 cubic centimeters cm3 16.3871 cubic inches in3 liters l 0.0163866 degrees (angle) radians rad 0.0174533 Fahrenheit F Celsius C C=5 (F–32) / 9 feet ft meters m 0.3048

feet of water ft H2O bar bar 0.0298907 fluid ounces, UK UK fl oz cubic centimeters cm3 28.413 fluid ounces, US US fl oz cubic centimeters cm3 29.5735 foot pounds f ft lbf joules J 1.35582 foot pounds/minute ft lbf/min watts W 81.3492 gallons, UK UK gal liters l 4.54596 gallons, US US gal liters l 3.78531 horsepower hp kilowatts kW 0.7457 inches of mercury in Hg millibar mbar 33.8639

inches of water in H2O millibar mbar 2.49089 inches in centimeters cm 2.54 inches in millimeters mm 2.54 kilogram force kgf newtons N 9.80665 kilogram f. meter kgf m newton meters Nm 9.80665 kilogram f. /sq. centimeter kgf/cm2 bar bar 0.980665 kilopascals kPa bar bar 0.01 kiloponds kp newtons N 9.80665 kilopond meters kp m newton meters Nm 9.80665 kiloponds/square centimeter kp/cm3 bar bar 0.980665 metric horsepower kilowatts kW 0.735499 microinches in microns m 0.0254 millimeters of mercury mm Hg millibar mbar 1.33322

millimeters of water mm H2O millibar mbar 0.09806 newtons/square centimeter N/cm2 bar bar 0.1 newtons/square meter N/m2 bar bar 10–5

28 Conversion Factors

To convert Into Multiply by

Into To convert Divide by Unit Symbol Unit Symbol Factor pascals (newtons/sq meter) Pa bar bar 10–5 pints, UK UK pt liters l 0.568245 pints, US US liq pt liters l 0.473163 pounds (mass) lb kilograms kg 0.4536 pounds/cubic foot lb/ft3 kilograms/cubic meter kg/m3 16.0185 pounds/cubic inch lb/in3 kilograms/cubic centimeter kg/cm3 0.0276799 pounds force lbf newtons N 4.44822 pounds f feet lbf ft newton meters Nm 1.35582 pounds f inches lbf in newton meters Nm 0.112985 pounds f/square inch lbf/in2 bar bar 0.06894 revolutions/minute r/min radians/second rad/s 0.104720 square feet ft2 square meters m2 0.092903 square inches in2 square meters m2 6.4516  10-4 square inches in2 square centimeters cm2 6.4516 Hydraulic Formulas

Horsepower: Conversion Factors: Pressure (PSI) = feet head  0.433  specific gravity.  1 hp = 33,000 ft. lbs. per minute Horsepower = GPM PSI 1714 1 hp = 42.4 btu per minute Specific gravity of oil is approximately 0.85. 1 hp = 0.746 kwhr (kilowatt hours) Torque: Thermal expansion of oil is 1 U.S. gallon = 231 cubic inches. approximately 1 cu.in. per 1 gal. per  Torque (lb. in.) = CU IN./REV. PSI Pipe volume varies as the square of the 10F rise in temperature. 2π diameter; volume in gallons = 0.0034 D2L  Torque (lb. in.) = HP 63025 RPM where: D = inside diameter of pipe in inches Flow: L = length in inches  Flow (gpm) = CU IN./REV. RPM Velocity in feet per second = 231 0.408  flow (gpm) Overall Efficiency: D2

Overall efficiency = Output HP 100 where: D = inside diameter of pipe in Input HP inches Atmospheric pressure at sea level = Volumetric Efficiency: 14.7 PSI Volumetric efficiency = Output GPM 100 Atmospheric pressure decreases (pump) Theoretical GPM approximately 0.41 PSI for each one thousand feet of elevation up to Volumetric 23,000 feet efficiency = Theoretical GPM 100 (motor) Input GPM

29