Differential drive mechanisms

摘要

A differential drive mechanism comprises a cage, which is rotatable about a first axis and represents the input, two coaxial output shafts which are rotatable with respect to the cage about the first axis, a coupling which is connected eccentrically to the two output shafts to transmit relative contra-rotational movement between them by connections which permit relative rotation of the coupling and the output shafts about a second axis parallel to the first axis and a restraint member which is coupled to the cage and to the coupling such that the coupling is rotatable with respect to the cage about a third axis perpendicular to the axis and capable of reciprocation in a direction perpendicular to the first axis but prevented from movement in a direction parallel to the first axis. The eccentric connections are constituted by a respective eccentric hole in the inner end of each output shaft in which the associated end of the coupling is received. The inner end of each output shaft is in sliding engagement with the inner surface of the cage whereby as the cage rotates about the first axis the sliding surface on the inner end of each output shaft is pressed by the coupling into contact with the opposing sliding surface on the cage so that a proportion of the input torque transmitted to the cage is transmitted directly to the output shafts through the cooperating sliding surfaces and does not pass through the coupling and restraint members.