Abstract: A linear weight actuator includes a clamp assembly adjustably connecting the power screw to the output spindle. The assembly includes an integrally formed key, riding in a slot formed in the actuator housing, which obviates the need for a separate key element. A mounting plate is adjustably clamped to the actuator housing, by a threaded mounting nut, such that the plate may be conveniently rotated relative to the housing. A linear bearing disposed in the mounting nut provides lateral support for the output spindle at a point spaced from the clamp assembly. A clamping ring encircles a thinned segment of the power nut and urges it against the power screw to prevent backlash.

Abstract: A pneumatic stepper motor weight actuator captures the advantages of polymeric harmonic gears while occupying less space and eliminating the problems associated with air entrapment in the stator grooves. Air entrapment is eliminated by providing orificed air passages from the bottom of the longitudinal stator grooves to the center stator hole. Advantageously, the actuator includes a rigid gear comprising a toothed polymeric sleeve adhesively bonded inside a metal cup.