Torque control actuator

Claim 1

A torque control actuator, comprising: a clutch including: (a) an input shaft adapted to be rotatively driven by a prime mover; (b) an output shaft adapted to rotatively drive a workpiece; and (c) means connecting the input shaft to the output shaft to rotationally drive the output shaft in response to rotation of the input shaft below a first predetermined torque, said means allowing the output shaft to slip relative to the input shaft above the predetermined torque; first rotary engagement means coupled to the output shaft to rotate with the output shaft; second rotary engagement means axially slidable relative to the first rotary engagement means into and out of engagement with said first means, said second means having a cam surface defined thereon, said cam surface having a ledge facing axially away from the first means, a leg portion extending from an end of the ledge toward the first means and an inclined return portion axially opposed from the leg and ledge and extending axially away from the leg and ledge from an angular position of the leg to the angular position of an ledge; cam means rotatively driven at the speed of said input shaft, said cam means being connected to the second rotary engagement means so as to cam on the cam surface of the second rotary engagement means; an axially moveable control for effecting a desired operation; means for translating axial movements of the cam means to the control; means biasing the cam means, the second rotational engagement means, the translating means and the control to an initial position in which the second rotary engagement means is out of engagement with the first rotary engagement means; and releasable means for axially moving the control, the translating means, the cam means and the second rotary engagement means against the force of the biasing means in response to operation of the prime mover; wherein: (a) upon initial operation of the prime mover below the first predetermined torque exerted on the workpiece, the moving means urges the control, the translation means, the cam means and the second rotary engagement means from an initial axial position to a second axial position, said axial movement causing said cam means to abut the ledge of the cam surface and thereby engage the first and second rotary engagement means so that both said engagement means rotate with the output shaft; (b) at operating torques at least as great as the first predetermined torque the output shaft slips relative to the input shaft and the cam means cams off the ledge into the leg to move axially relative to the second rotary engagement means to a third axial position, said axial movement allowing the control to move to a corresponding third axial position; and (c) release of the moving means allows the biasing means to return the cam means, second rotary engagement means, translation means and control to the initial position, whereupon the cam means cams on the return portion of the cam surface to angularly align the cam means with the ledge of the cam surface in the initial position.