Self-locking differential gear

A method of altering the torque output ratio of a differential of the type comprising two output cam members rotatable about an axis, each said member having a single annular cam surface thereon of undulating form comprising pairs of mutually inclined surfaces, one of said cam members having a different number of said pairs of inclined surfaces thereon than the other of said cam members, the cam surfaces on the cam members being frusto conical and converging towards each other, and a plurality of cam followers having end surfaces engaging the cam surfaces of the output cam members, the arrangement being such that relative contra rotation of said output cam members causes the cam followers to slide axially, and an input element engaging the followers which are slidably supported by the input element and moving the followers circumferentially relative to the output cam members, the input element engaging with a radially outer portion of each cam follower to move the follower circumferentially relative to the cam output members, and supporting the two cam output members against axially outward movement during drive of the cam output members through the followers, wherein the output cam member having the higher number of pairs of inclined surfaces thereon frictionally engages the input element with a higher frictional force than the other output cam member in order to reduce the difference between the torque output ratio of the output cam members when making a right-hand turn compared with the torque output ratio when making a left-hand turn, said method comprising:

• causing the output cam member having the higher number of pairs of inclined surfaces thereon, to frictionally engage the input element with a higher frictional force than the other output cam member in order to reduce the difference between the torque output ratio of the output cam members when making a right hand turn.