Patent GB-877017-A (GB)
Title: Improvements in and relating to a gear box control mechanism
IPC: F15B1/02
Filed: 1959-05-21
Abstract: 877,017. Change-speed control. COMPAGNIE DE PONT-A-MOUSSON. May 21, 1959 [May 22, 1958], No. 17276/59. Class 80 (2). [Also in Group XXXIV] Each of the ratio establishing brakes and/or clutches of a change-speed gear is engaged when liquid under pressure is admitted from a manually actuated ratio selecting valve to a second valve, comprising a main passage and a throttled by-pass passage, and thence to a simple servomotor, build-up of pressure in the servomotor conditioning the second valve to close the main passage so that completion of engagement of the ratio establishing brake is effected by the slow flow of liquid through the throttled by-pass passage. The throttle by-pass passage includes a restricting needle valve adjusted by actuation of the accelerator pedal controlling the engine of a motor car in which the gearing is mounted, depression of the accelerator pedal for increased engine torque acting to open the restriction for rapid completion of brake engagement. In one form, oil under pressure supplied from an engine-driven pump 32, Fig. 1, to a pipe 29 and a hand-operated ratio selecting valve S, passes through a pipe 9a to a valve T which, when a ratio establishing brake band 3 is disengaged, connects directly through a main pipe 9 to a brake operating servomotor V. As the pressure in the pipe 9 and the servomotor V increases during brake engagement, a pipe 10 feeds this increasing pressure to the end of a valve piston 25 which is moved against the bias of a spring 27 to shut off direct communication between the pipes 9a, 9 and instead open communication between the pipe 9a and a pipe 11 which leads through a restricted orifice E to the pipe 9. Accordingly, completion of brake engagement is effected slowly by bleed of oil through the orifice E. A needle valve 13 controls the size of the orifice E, and is connected by links 18, 20, &c., to the accelerator pedal 21 of the engine in a motor car containing the change-speed gear. When the accelerator pedal 21 is depressed for maximum engine torque, the needle valve 13 is substantially withdrawn from the orifice E, so that liquid passes therethrough more readily for relatively rapid completion of brake engagement. The hand-operated ratio selector valve S also controls the supply of oil to pipes 9b ... 9d, each leading in turn to a valve similar to the valve T and controlling the rate of flow of liquid to a servomotor applying a ratio establishing brake in the change-speed gear. Each of these valves is similarly provided with a throttled restriction E adjusted by depression of the accelerator pedal 21. In a modification, the needle valve 13 of each valve T is replaced by a composite valve assembly consisting of four frusto-conical parts connected apex-tobase, each part controlling the passage of oil under pressure through the associated pipe 11 of one of the valves T in the pipes leading to a ratio establishing brake engaging servomotor, Figs. 3, 4 (not shown). In another modification, a brake-engaging servomotor V, Fig. 5, is supplied with oil under pressure through the pipe 9a and a valve T<SP>1</SP> which serves only to close communication between the pipes 9a, 9, an accelerator-pedal controlled throttling needle valve E<SP>1</SP> lying in a pipe 44 directly connecting the pipes 9a, 9.