Warner Electric wrap spring clutches and brakes are a simple, low cost and easily adaptable answer to various stop-start applications. Ideally suited to rotary indexing tables, their speed and accuracy offers both excellent repeatability (as there is no cumulative error) and minimum system inertia.
The torque generated by a wrap spring clutch arises from the cross-sectional strength of the spring and is independent of speed. The greater the force of rotation, the more tightly the spring grips the hubs.
Wrap spring clutch/brakes also offer dramatic advantages in torque-to-size ratios when compared to many other torque control devices, such as hysteresis, magnetic particle and friction disc units.
While the starting time of a friction clutch is inertial and frictional load dependent, the wrap spring clutch is not. The total time to speed will be constant, irrespective of load.
It is important to select the correct size for the job. A wrap spring clutch engages almost instantly, and the higher the load, the tighter the spring wraps down. It is not forgiving in the sense of a friction disc unit and it must be sized correctly for each application.