Bi-directional spring clutch for reducing worm gear drive

Abstract

Bi-direction spring clutch apparatus for a reducing worm gear drive is disclosed. The bi-directional spring clutch apparatus includes a worm gear drive comprised of a worm and an output shaft rotatably mounted in a housing. A worm gear is rotatably mounted coaxially about the output shaft so that its teeth mesh with the threads of the worm. The worm gear includes two coaxial extensions which are also rotatably mounted coaxially about the output shaft but which are rotatably fixed relative to the worm gear. Located adjacent to each of the coaxial extensions of the worm gear are two torque transfer bushings. These are of the same outside diameter as the coaxial extensions, but are rotatably fixed relative to the output shaft. Stretched over each of the torque transfer bushing/coaxial extension pairs is a wound spring, each of the same hand of winding, and each having sufficient revolutions to result in self-locking of the torque transfer bushing/coaxial extension pairs. The end of each spring is bent radially outward to form a tang which projects through notches located in a cylindrically shaped control sleeve rotatably mounted coaxially about each spring. The control sleeves have a radial flange into which are machined radially spaced notches. By rotationally controlling the control sleeves, the wound springs can be permitted to lock up the torque transfer bushing/coaxial extension pairs or they can be prevented from doing so regardless of whether torque is being applied to the worm or to the output shaft.