GB800712A - A stepless variable-speed transmission - Google Patents

Abstract

800,712. Variable-speed gear. GROLL, R. C. Aug. 26, 1954 [Aug. 26, 1953], No. 24880/54. Class 80 (2). [Also in Group XXIX] A variable-speed gear comprises a throttled gear pump of which one wheel 37 is fast on an input shaft 36, whilst a meshing wheel 38, carried planet-wise in a freely-rotatable housing 44, is fast with a planetpinion 40 meshing a sun 41 on a final output sleeve 42 carrying an output gear-wheel 43, the pump serving to transfer oil from an external reservoir 45 to a pressure space inside the housing 44 and thence back to the reservoir through an outlet duct 55, which is inclined in the direction of and angularly spaced from the pump inlet 50, and includes a centrifugal and pressure-responsive control valve 53 for throttling the outlet duct to produce an eventual oneto-one drive. Vanes 76 on an impeller 75, in the reservoir space 45 and secured to the output sleeve 42 or input-shaft, feed oil towards the pump inlet 50 on starting and maintain uniform angular speed of the oil in the reservoir during running. The control valve 53 comprises a tube 53, Fig. 3, with ports 58, 68 which control inlet and outlet ducts 52, 55 as the tube is turned, by a centrifugal mass 59 on an arm 63 damped by a dashpot 61, or by equivalent balls, rollers, chains or cables in a duct. Housing pressure also acts on a spring-loaded piston 67 to increase the flow at high pressures. Excess pressure in the reservoir 45 is relieved to the housing through a spring-loaded valve 71. A definite minimum ratio is provided by a ball detent 25 preventing the housing 44 from reverse rotation and also having an arm 28 which pushes the centrifugal lever 63 radially inwards to open the control valve 53 fully during fixed ratio drive.