Clutch Functions and Applications

Clutch Functions and Applications All Formsprag/Stieber clutches described is based on the accumulation of many are divided into three basic types of in this catalog are “overrunning” clutches, years of experience in the design, applications for which they are intended . i .e ., they will drive in one direction but con struction and application of The three basic applications are: overrun (freewheel) in the other direction . overrunning clutches . In physical The preparation of a catalog such as this appearance, the Formsprag/Stieber • Overrunning can be undertaken only by a company catalog overrunning clutches are all very • Indexing having very broad experience in all much alike . However, different types • Holdbacks or Backstops aspects of the use and application of of applications will involve differing overrunning clutches . load character istics and will call for These three categories are described in variations in the technical details of clutch greater detail under those headings in this Formsprag/Stieber is such a company, construction . For this reason the clutches catalog . and the information given in this catalog Overrunning clutch Indexing clutch Backstopping clutch This class of applications is typified by In this type of application, re cip ro cat ing In backstopping or holdback* applications, standby and compound drives . For motion applied to the driving race is one race is always fixed to a stationary ex am ple, a steam turbine and a standby trans formed into intermittent motion in ground member . The function of the electric motor may be con nect ed to a only one direction at the driven race . For clutch is to permit ro ta tion of the sin gle driven shaft through overrunning example, if a pinion is connected to the mechanism, con nect ed to the other clutches . The shaft can then be driven by driving race, a rack meshing with the race, in one di rection only, and to prevent either the turbine or the motor or both with pinion can give reciprocating mo tion to any ro tation in the reverse di rec tion at no further modification of the installation . the driv ing race . The clutch will then all times . Although the clutch nor mal ly The turbine drive clutch au to mat i cal ly ad vance or “index” the work (driv en race) overruns most of the time, it is re ferred to engages when the tur bine starts to drive, on each forward stroke of the rack, but as a holdback or backstop in conveyors, but au to mat i cal ly over runs when the load will not return or back-up on the return gear reducers and sim i lar equipment is transferred to the electric motor . stroke of the rack . because its func tion is to pre vent reverse rotation . Considerations Considerations * “Holdback” is a name given to a back stop clutch when mounted on an inclined con vey or • Type of motor • Number of cycles/min head shaft. • Max starting torque • Index angle • Internal combustion engines, • Nominal torque please consult Formsprag • Inertia (WR2) of the driven masses Considerations • Nominal driving torque • Accelerations of the driving • Motor breakdown torque • Range of driving speed member • Maximum dynamic reverse torque • Inertia (WR2) of the driven masses • Number of indexes during due to elasticity of the locked parts: • Range of overrunning speed service life elastic belts, shafts of more than • Number of starts during service life • Shaft diameter 9 feet (3 meters) long • Shaft diameter • Range of overrunning speed Applications • Number of torque applications during service life Applications • Metal stamping • Shaft diameter • Dual motor/engine drives • Pressworking • Conveyor belts • Packing machines • Creep and starter drives • Indexing tables Applications • Disengagement of centrifugal mass es • Assembling machines • Inclined conveyors • Printing machines • Escalators • Pumps • Gear drives • Fans 2 www.formsprag.com P-956-FC 8/18 Clutch Functions and Applications Backstopping VFB & HFB models provide automatic backstopping for fans to prevent wind milling when the fan is turned off, actuates instantaneously to prevent any reverse rotation . Dual Drive FSO clutches are used in dual drive applications to provide instantaneous clutching from one drive to the other in case of the failure of either . Indexing Indexing clutches are used to con vert re cip ro cat ing linear Backstopping mo tion to in cre men tal rotary motion for conveyor or The LLH Holdback clutch is used to backstop (prevent ma te ri al feed ap pli ca tions . reverse rotation) the incline conveyor in a material Clutch Models: HPI, AL handling application . Clutch-Couplings Clutch Couplings are used for dual drive of a pump or fan, and when there is a need to connect inline shafts . Backstopping The clutch coupling prevents backdriving of the other drive source when operating at motor speeds . Clutch FHB backstops are mounted on the double extended couplings allow for the tran si tion from one drive source input shaft of gear reducers and provide instantaneous to an oth er without controls . automatic backstopping to the drive system for typically Clutch Models: FW, FWW, ALKMS, RIZEL,AL . .KMSD2, inclined conveyors and bucket elevator applications . RIZ . .ELG2 P-956-FC 8/18 www.formsprag.com 3.

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