Rotary tool-driver with automatic torque governed declutching - uses variable torque-sprung ball coupling with ratchet clutch override

摘要

The hand-piece is used to drive a rotary tool (6) and disengages at a set torque, the disengage coupling being sited between the handle (1) and the driving head (3). The pressure applied by a coil spring (8) is modified to vary the disengage torque, applied to caged (18) balls (16) constituting the coupling. An adaptor sleeve (21) fits between the cage (18) and the head, locates the balls on its top face (21'), and can rotate relative to the head in one direction to prevent or override disengagement. A ratchet mechanism prevents the relative rotation associated with disengagement, and acts on an interface between the bottom of the adaptor and shoulder (3'). Sprung pins (22) in part-circular grooves (24) with unilaterally ramped floors may provide the ratchet effect and a polygonal section head formation (26) may house into the cage.