GB449586A - Improvements in or relating to worm reversing gearing - Google Patents

Abstract

449,586. Variable-pitch propellers. FAIREY AVIATION CO., Ltd., and FAIREY, C. R., Cranford Lane, Hayes, Middlesex, and FORSYTH, A. G., Venlaw, Burdon Lane, Cheam, Surrey. June 6, 1935, No. 16494. [Class 114] [See also Group XXIV] In worm reversing- gearing, the direction of rotation is reversed by altering the sense of the worm and to this end a single convolution of the worm is formed as a discontinuous resilient circular rib e, Figs. 1 and 2, which is adapted to lie in either of grooves c or d on a worm shaft a to form either a right-hand or left-hand worm, a further groove b being provided for an inoperative position of the rib e. With this arrangement the change of sense of the worm has to be effected manually when the parts are stationary, but in the arrangement in Figs. 7 and 9, the change can be effected during the relative rotation of the parts. This arrangement illustrates the application of the invention to variable-pitch propellers, the worm shaft a being stationary and worm wheels such as f, secured to individual propeller blades, having a planetary motion around the axis of the shaft a. The worm comprises as before a resilient circular rib e secured at one end to the shaft, the other end being secured to a block m which is capable of lateral movement in a slot n to move the rib e into the left-hand or right-hand thread position against the helical side walls of a groove h, or to retain it in its central and neutral position as shown. This lateral movement of the rib e is obtained by axial movement of an inner sleeve j, to which the block m is secured, slidably keyed to the shaft a and movable by means of pins t engaging in inclined slots v, these pins being secured to a rotatable control ring q and projecting through slots u in the shaft a.