Torque transmitting device

A device for transmitting torque between a shaft and an outer annular element, comprising;

• at least one eccentric device arranged for rotation with the shaft, said eccentric device including a cam element which is displaceable at right angles to the input shaft and which is biased towards its outermost position by means of a spring;
• and a plurality of rocker arms in a uniform spaced relationship around the shaft which can be activated by the eccentric device, each of the rocker arms provided with engaging means arranged to be brought into driving engagement with the annular element by movement of said rocker arm, and in which device the effective length of the eccentric device is arranged to vary in dependence upon the force required to activate a rocker arm, thereby to obtain between the shaft and the annular element a transmission ratio which varies in dependence upon the load on the annular element.