Differential drive mechanism

A drive mechanism for interconnecting rotatable driving and driven members, said drive mechanism comprising:

• gear means for transmitting drive forces between said driving and driven members and for enabling relative rotation to occur between said driving and driven members;
• main clutch means operable between an engaged condition in which said main clutch means is effective to retard relative rotation between said driving and driven members and a disengaged condition;
• and actuator means for effecting operation of said main clutch means from the disengaged condition to the engaged condition in response to a predetermined rate of relative rotation between the driving an driven members, said actuator means including a flyweight, an axially extending member mounted for rotation, drive means for rotating said axially extending member about its axis at an angular velocity which varies as a function of the relative rotation between the driving and driven members, support means for pivotally supporting said flyweight for rotation with said axially extending member and for radially outward movement of at least a portion of said flyweight away from the axis of rotation of said axially extending member, means for effecting operation of said main clutch means from the disengaged condition to the engaged condition upon outward movement of said flyweight to a predetermined position, and stop means for engaging said portion of said flyweight and for rotatably moving with said flyweight to limit the extent of said radially outward movement of said portion of said flyweight beyond said predetermined position to absorb at least a portion of the loading on said pivotal support and to prevent retardation of rotation of said flyweight by said stop means when said radially outward movement is thereby limited.