How do freewheels work?

The general mechanism of a freewheel is always the same. A shaft transmits energy to a hub. At the moment when the power transmission stops, or the shaft turns slower than the hub, the freewheel prevents the hub from braking. Even if the shaft rotates in the opposite direction, the freewheel ensures that the hub remains in rotation until the energy supplied has been used up.

To make it more vivid, vizualize a freewheel, as if you´re riding a bike.As long as you pedal, power is transmitted via the pedals and chain to the wheel hub. If the cyclist stops pedalling, the bicycle does not stop right away. A freewheel in the wheel hub ensures that the bicycle continues to roll even though the driving shaft no longer rotates and transmits power.

If you ride your bicycle downhill, the freewheel prevents you from having to pedal as fast as you pick up speed.

In the classic sense, a sprag functions is an element of torque transmission. Depending on the occasion and the need, rigid sprags can be replaced by sprag rollers or springs. The requirements for a freewheel differ especially with regard to power and speed and make different technical designs necessary

What types of freewheels are there?

self contained freewheels

Non-bearing sprag or roller freewheels offer the advantage of direct mounting by means of different variants of flange covers, which can be mounted on gearboxes, motors or other drives, by means of screw connections. Freewheels with torque limitation are also available. Due to their design, they can also be used as backstops in gearboxes, as mechanical protection in the event of an operating failure.

This can save enormous costs, because the more expensive the gearbox or motor is, the more a mechanical protection by means of a self contained freewheel can replace the costly installation of a brake.

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built-in freewheels

built-in freewheels have a wide range of applications. For example, they can be used as indexing freewheels or backstops. Their advantage lies, among other things, in the possibility of space-saving installation. The installation is carried out by means of a press or key connection.

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combined bearing freewheel products

combined bearing freewheel products are available in various designs. They are used where there is a low torque. Rolling bearing freewheels are offered with and without groove as well as with and without seals. They are maintenance-free. They also have integrated rolling bearings, saving space and time for the installation of an additional bearing.

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centrifugal lift off sprags freewheels

Backstops as well as overrunning clutches are referred to as centrifugal lift off sprag freewheels. These freewheels operate without contact in overrunning mode. The special focus here is on the speed in overrunning as well as in driving operation. This variant of the freewheel works absolutely wear-free, which leads to an extremely long service life with all the resulting advantages.

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