Patent GB-734016-A (GB)
Title: Variable speed gear box
IPC: F16H3/72
Filed: 1952-05-28
Abstract: 734,016. Variable-speed gearing. BOWLES, C. V. May 28, 1953 [May 28, 1952], No. 13510/52. Class 80 (2). Automatically-variable epicyclic gearing comprises a sun wheel 1 fixed to an input shaft 2, with planet pinions 3 carried in a driven casing 9 and operating, through cranks 5 or the like, piston pumps which have tangentially-arranged cylinders 8 secured in the casing and which draw fluid from the casing through non-return valves 11 and deliver it through non-return valves 13 and pipes 13A to a plunger assembly controlling its return to the.casing, the movement of the plunger being responsive to output load. As shown in Figs. 1, 2, the casing 9 is secured to an output shaft 10 and the control plunger 21 is slidable axially in a cylindrical extension 16 of shaft 2 journalled in a sleeve 17 fixed in casing 9. One or other of a pair of opposed semi-circular slots 18 at the ends of cylinder 16 communicates through a slot in sleeve 17 with a channel 14 to which the pipes 13A deliver, the other slot 18 then registering with an outlet port (not shown) to the casing. Plunger 21 is subject to the action of opposed springs 22, 23, whereby the gear ratio varies with output load. The action may be modified by adjusting the force of the springs 22, 23 by means of a ram 24 forming the abutment for spring 23 and subjected to fluid supplied through a pipe 25 at a pressure determined by an adjustable relief valve, such adjustment being effected either manually or by interconnection with the accelerator pedal so that when the pedal is released the springs 22, 23 are fully relaxed and plunger 21 can slide without restraint, discharging fluid from one end of cylinder 16 as it is supplied to the other end, while as the pedal is depressed the ram 24 progressively compresses the springs to impose resistance to movement of plunger 21. In the form shown in Fig. 6, the pipes 13A deliver fluid into a cylindrical extension 39 of a spindle 43 splined in casing 9 and threaded into output shaft 10. The wall of cylinder 39 has three axially-spaced ports 41 of progressively-increasing length and each co-operating with a set of control plungers 54 slidable axially in cylinders 46 formed in a member 42 fixed to shaft 2, each cylinder 46 communicating at the left-hand end with a radial passage 55 adapted to register, during relative rotation of shaft 2 and casing 9, with the port 41 or with a discharge port 45 diametrically opposite to port 41, the right-hand ends of the cylinders 46 being connected through an annular passage. In the position shown, for example, fluid enters the top cylinders 46 through ports 41 and drives the top plungers to the right, the fluid to the right of those plungers driving .the bottom plungers to the left, and the fluid to the left of the bottom plungers being discharged into casing 9 through ports 45. The fluid pressure in cylinder 39 tends to move spindle 43 to the left, so as to close the ports 41 and give solid drive, while output load tends, through the screw connection between 10 and 43, to move 43 to the right to open the ports 41 successively, giving geared drive. Another form of plunger assembly comprises a spring-loaded plunger 29, Fig. 5, slidable in a sleeve 28 within a housing rigid with casing 9 under the control of a cam 30 on shaft 2. Fluid delivered by the pumps to a port 34 passes, under control of a piston valve 33 operated by a second cam 35 on shaft 2, to a port 31 whence it passes, under control of plunger 29, into the sleeve 28 and to a discharge port 32 controlled by valve 33. The end 29A of plunger 29 is inclined so that the automatic control action may be modified by angularly adjusting the sleeve 28. Additional fluid is drawn into sleeve 28 from casing 9 as required through a non-return valve 36. Means may also be provided for varying the stroke of the pumps or for angularly adjusting sleeve 28 in accordance with output load.