In a perfect world, freewheels are overrunning clutches, when they will drive one way and overrun the freewheel the other way. In addition to being used as backstops, they can also be used as overrunning clutches or indexing freewheels. Many people use ruedas libres for backstopping. Mounted on the inclined shafts of conveyors, backstops are commonly called holdbacks. The purpose of this article is to provide information on the construction, functionality, and installation of freewheels.
Working of Freewheels
A freewheel is a machine element that possesses the following characteristics:
- Freewheeling occurs when the inner and outer rings do not make contact in one rotational direction.
- The inner and outer rings come into contact in the other direction of rotation; this direction can stop rotation or transmit high torque.
- A freewheel has an outer ring and an inner ring, both of which contain clamping elements. Clamping elements come in several types.
- Freewheels have an outer ring that rotates clockwise while their inner rings remain stationary.
- When the outer ring is turned the other way (anticlockwise), the inner and outer rings come into contact, driving the inner ring. A high torque can be transmitted when rotating in this direction (anticlockwise).
- During freewheeling operations, the outer ring is free to rotate freely when the inner ring is turning slower than the outer ring.
Freewheels come in two basic designs:
- Sprag freewheels
- Roller freewheels.
On the outer and inner rings of a sprag freewheel, there are cylindrical tracks.
When the outer ring with the stationary inner ring is rotated in the opposite direction, clamping is enabled. As a result, the sprogs are prevented from sliding along the tracks. It is possible to transmit a high torque in this rotation direction (driving operation).
Sprag ruedas libres can also be operated by turning the inner ring clockwise and the outer ring counterclockwise for freewheeling and driving.
Roller ramps are either found on the inner or outer ring of roller freewheels, as shown in the above image. There is a cylindrical track on one of the rings. A spring-loaded roller is placed between the rings.
By rotating the outer ring in the opposite direction from the stationary inner ring, clamping becomes effective. Thus, the rollers are prevented from slipping between the tracks. With this direction of rotation, high torques (driving operation) can be transmitted.
Freewheeling is also possible in this design when the inner ring is rotated counterclockwise, and driving is possible when the inner ring is rotated clockwise.