GB1310515A - Transmission systems - Google Patents

Abstract

1310515 Change-speed control CAV Ltd 29 June 1970 [7 July 1969] 34134/69 Headings F2D and F2C In a synchronized-shift motor-vehicle countershaft type change-speed gear control, movement of a manually operated gear-shift lever 23 into an alternative gear selecting position energizes an actuator 26 to partly free, i.e. ease, the main clutch 10 and, further, modifies an engine throttle control 25 whereby a gear establishing signal is supplied from a control unit 22 to electromagnetically operable valves (not shown) controlling a fluid-pressure operated gear-shift servo-motor unit 19 on balanced energization of polarized differential synchronism detectors 20, 21 mounted on the input and output shafts of the gear-gox, the output signals of the detectors 20, 21 being compared in the control unit 25 which produces its signal for gear-shift actuation when the compared signals indicate that the relative speeds between the input and output shafts is zero. As shown, an engine 11, normally controlled by a manually operated fuel control lever 24, drives via the main clutch 10 and constant-mesh sliding dog clutch controlled C.S.G. 16 to the output shaft 13. Assuming the sliding dog clutch 17 on the output shaft 13 is coupled to the input gear 14 for direct drive, when the gear lever 23 is moved to the low gear position the actuator 26 is energized to ease the main clutch 10 through the intermediary of a spring 27 and simultaneously the servo 19 disengages the dog clutch 17 and moves it into the central neutral position. A signal is then passed to the throttle control 25 which increases the engine speed, which increase in speed is transmitted via the clutch 26 to the gear-box and when the relative speed of the dog clutch 17 and low gear 15 are zero the servo 19 effects engagement thereof. Fig. 2 illustrates an alternative form of main clutch, engagement of which is effected by independent nested sets of springs 33, 36 the pressure plate being formed in two parts 32, 33 loosely connected with lostmotion by a lip 37 formed on the outer plate 35, the inner light springs 33 passing through holes in the outer plate 35 to separately load the inner plate 32 and provide a two-stage clutch release, the light springs 33 solely serving to transmit the limited torque when the main clutch is eased during synchronism. Further movement of the outer plate 35 additionally moves the inner plate 32 to fully release the main clutch for starting purposes. In a further alternative clutch arrangement, two driven clutch plates are held in spaced relationship by light springs such that during partial clutch engagement the clutch plates are outwardly urged by the light springs alone into engagement with the driving clutch members to transmit the limited torque, full clutch engagement being effected by the normal clutch springs which compress the driving and driven clutch parts and plates together, thereby compressing and overriding the light springs.