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http://rbearing.en.made-in-china.com/product/EKGQhdNrhMkR/China-Sprag-Freewheel-Instead-of-Gmn-One-Way-Clutch-Fe442z.htmlFreewheel-clutches transmit or support torque moment by friction contact in one direction and permit idling in the opposite direction.
Freewheel-clutches are used as:Indexing elements to change from oscillating to intermittent rotary motion.Backstops to prevent self reversing due to load condition when the machine is not activated.Overrunning clutches to maintain driven unit activated even during slowdown, or in the case of two speed operation (by independent motors) to switch to the higher speed by passing the slower.A large quantity of freewheel-clutches with varying design features and dimensions are available, depending on requirements such as: Torque, indexing frequency, idling speed and environment.The supporting equipment around the clutch has to be built accurately and of high quality for the clutch to operate properly This is why we offer support units or complete assemblies of freewheel clutches. Lubrication is especially important to obtain maximum life of freewheel clutches. Good lubrication decreases drag. Please refer to our Lubrication Selection Table for proper selection.Clutches (except the sealed Clutches of series FND, FPD, FK 62...-RS, FK 62...-2RS, FKN...-RS and FKN...-2RS) are shipped rustprotected not lubricated.
For extreme applications, please consult with our technical staff.
FE448 ;FE443 ;FE422; FE423 ; FE428; FE427 ;FE432; FE433 ;FE453 ; FE437 in stock. 

MARKS

A large quantity of freewheel-clutches with varying design features and dimensions are  available  , depending on requirements such as: Torque, indexing frequency, idling speed and environment.
 

The supporting equipment around the clutch has to be built accurately and of high quality for the 

clutch to operate properly .This is why we offer support units or complete assemblies of freewheel 

clutches.

How Do Sprag Clutches Work?

A sprag clutch resembles a roller bearing, but instead of allowing the elements to roll freely in both directions the rolling elements lock when rolled the oposite direction. Sprag clutches have three main operations: overunning, indexing and backstopping. The sprag clutch consists of a series of cam shaped steel wedges (or sprags). Each sprag is placed at an angle to permit rotation in one direction, yet provides instantaneous backstopping in the other.

Torque is transmitted from one race to the other by the wedging action of the sprags, consistently providing safe and reliable performance. A sprag clutch is designed so that the maximum number of sprags can be accomodated, enabling greater torque transition in comparison to its size and weight.

Function: The sprag clutch design shows at the contact surfaces a sophisticated geometrical shape, the engagement curve, which results in a certain pitch angle (?a, ?i ) when the sprags get in contact with the round mating parts. When torque is applied to the clutch the sprags roll in along the engagement curve until an equilibrium of forces between the torque and tension in the sprags and mating parts is achieved. This part of the engagement curve is called operating zone.

The engagement curve has to meet the operating condition (? <= µ) (µ = coefficient of friction). The size of the engagement angle ? is determined by the applied torque and the force of reaction of the expansion ? of the mating parts. The engagement angle ? creates an angle of twist between outer an inner ring which will remain equal with constant operating conditions and should not be considered slippage or intermittent slippage.

The logarithmic spiraled engagement curve

The logarithmic spiraled engagement curve is the prerequisite for precise indexing and long operating life. To achieve these factors it is important that all sprags engage simultaneously and with the same angle for torque pickup. Equal force acting on all sprags is required from the instant of engagement to full torque transfer.

The special geometric shape of the logarithmic spiral along the engagement curve guarantees equal pitch angles between the sprags and round mating parts in each position of the engagement curve. This angle remains equal even with different position angles of the sprags.

Spring System
In order to provide instant torque transmission, the sprags have to be kept in friction contact all the time reliably with a spring system. We provide two spring systems:

Identification The Standard design of model FE 400 includes the meander spring system even when the suffix "M" has not to be added. For Z-type spring please add suffix "Z", e.g. FE 442 Z, FR 422 Z etc. Please note that our ball bearing sized clutches are available with Z-type spring system only.

Indexing

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Indexing elements change an oscillating motion into an intermittent rotary motion; or reverse. The most common explanation of this would be an assembly line or automatically fed production line. As seen here a production line that needs to move to the next position but then stop, wait, and then proceed one position and repeat. This motion can be controlled and protected with the use of Sprag Clutches. Many types of conveyers, assembly machines, and production machines can utilize Sprag Clutches for the process or machine/personnel protection in case of motor/electrical failure.

Indexing Applications

·                     Copiers: Paper Feeding

·                     Furniture Production: Glue Roller

·                     Food Production: Bottling Plant

·                     Sowing Machines: Material Feeder

·                     Automatic Winch: Controlled Raising/Lowering

Backstop

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This Clutch application is most commonly used for safety in case of machine failure. This could be an escalator to an elevator, or even the PTO on a tractor. If a machine is lifting a heavy object and the power goes out, a clutch can hold the weight in place protecting all that is involved.

Backstop Applications

·                     Conveyers: Stop load

·                     Winches: Stop load

·                     High Voltage Switching: Safety device

·                     Textile Machine: Material feed protection

·                     Industrial Fan: Motor Protection

Overrunning

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This type of Clutch application can take a couple of forms. The main one would be a reverse direction preventer to protect the machine it is mounted on. This is where the Clutch is spinning without being engaged, ‘Overrunning’, until failure occurs. At this moment the clutch would engage and hold the process in place. The opposite application would be when the clutch is engaged most of the time, but overrunning is required for successful operation. The most notorious application for this use is the bicycle.

Overrunning Applications

·                     Conveyers: Speed Compensation

·                     Mixers: Motor Protection

·                     Motorcycles: Gear Box or Transmission

·                     Packaging Machine: Spins Down Freely

·                     Printing Press: Ink Roller Drive