Patent GB-223285-A (GB)
Title: Improvements in speed changing mechanism
IPC: F16H29/12
Filed: 1923-07-11
Abstract: 223,285. Vessey, E. A., and Infinitely Variable Gear Syndicate, Ltd. July 11, 1923. Variable speed ratchet gearing of the type described in Specification 18909/13, in which a ratchet wheel is secured to a driven shaft and pawls are connected by links to a driving-shaft, so that a relative displacement of the axes of these shafts produces change in the speed ratio. Ellipse generators are provided to secure uniformity of motion of each pawl when it comes into driving position. A form yielding approximate compensation only is shown in Figs. 13, 15 and 19. The ratchet wheel 235 is on the driven shaft 236, and the pawl-actuating driving-shaft 212, which is laterally movable, is connected to a first-motion shaft 2 by a drag-link coupling 203. The ellipse generator comprises two pairs of pivots 205, and links 206, Fig. 15, which yield two mutually-perpendicular parallel motions to members 208, 209, respectively. Control is effected by varying the eccentricity of an eccentric 211. When the eccentric 211 is concentric with shaft 212, the main crank pin 216 of the generator describes a circle. In the other extreme position of the eccentric, the pin 216 describes a " mean ellipse." A series of links connect the pin 216 td a second main crank pin 221, Fig. 13. Each crank pin drives a set of hydraulically-actuated pawls 229, shown also in Fig. 19, which are arranged in different planes, and are carried upon nested sleeves 224, 225, which sleeves together form an oil-tight drum. Upon the peripheries of these sleeves are rings of radial hollow bosses 226, 227, and surrounding each boss and slidable upon it, is a cylinder 228 closed at the top and carrying there the pawl teeth 229. These pawl teeth are adapted to drive two rings of ratchet teeth 237 arranged internally upon a shell 235 which is adapted to be connected through a forward and reverse driving train 236<1> to the driven shaft 236 of the gearing. The drum within the nested sleeves, is kept full of oil by a pump 239, and an annular piston 233 is kept reciprocating within this drum by the relative turning of the sleeves 224, 225. This has the effect of alternately thrusting one ring of pawls outward into engagement and sucking the other ring of pawls inward for the idle stroke. This reciprocation is effected by a screw-thread 230 and castellations 231 on the two sleeves respectively. Means are provided for thrusting out both sets together for solid driving. In a much more complicated form of the invention the ellipse generator on each speed forms the ellipse required by theory to give a perfectly uniform speed to the pawl while in action. This form contains these separate mechanisms; (1) the Oldham - type coupling; (2) the ellipse generator, (3) the duplicator; (4) the speedvarying mechanism; (5) the pawl-operating mechanism; (6) the reversing-gear; (7) the automatic power control. The pawls in this form comprise pairs of plungers 52, Fig. 1, which are thrust apart axially by toggles 66 actuated by cams 70. The plungers 52 have toothed ends adapted to engage and drive positively opposed discs 58, 59 with toothed faces secured to the driven part 57. The teeth are in staggered relation so that the toggles can always open fully out.