GB847944A - Improvements in or relating to clutch control mechanism for motor vehicles - Google Patents

Abstract

847,944. Controlling clutches. AUTOMOTIVE PRODUCTS CO. Ltd. July 4,1958 [July 16, 1957; Oct. 9, 1957], Nos. 22534/57 and 31589/57. Class 80 (2). A motor vehicle centrifugal clutch of the type having a release collar 21 movable in one direction to disengage the clutch irrespective of the position of the centrifugal weights 31 and in the opposite direction to permit spring pressure to effect engagement through levers 23 is actuated by a servomotor capable of selectively taking up either of two positions, in one of which the release collar is held in such a position that the clutch is engageable only by operation of the weights, while in the other position it allows the clutch to be engaged by its springs without operation of the weights. In the arrangement shown in Fig. 1, the release collar 21 is connected by links 13, 15, 17, 18 to a piston 12 in a servo-cylinder 11, member 13 passing through a sleeve 43 secured to a second piston 42 loaded by a spring 48. The pistons divide the cylinder into a compartment 37 normally communicating with atmosphere, but also, by means of a valve 38, capable of being connected to a vacuum reservoir 39, a subcompartment 45 open to atmosphere, and a second sub-compartment 44 which may be placed in communication with atmosphere or vacuum by a piston valve 56 controlled by an engine-driven governor 58. In the low-speed position shown valve 56 places the servomotor in communication with an atmospheric port 54, whereby piston 42 is forced to the left to act as a stop preventing movement of piston 12 to the right, thus holding collar 21 in a position in which weights 31 may engage the clutch. When the speed rises to a predetermined value governor 58 operates valve 56 to place sub-compartment 44 in communication with a vacuum port 53, whereby the clutch springs are able to effect engagement, pistons 12, 42 being moved to the right against spring 48. In a second embodiment, Fig. 3 (not shown), the servo change-over valve is solenoidactuated, the solenoid being in circuit with the ignition switch and being controlled by governor-actuated contacts. In this arrangement also the clutch throw-out lever may be operated manually to move it from the position in which the clutch is engaged by the springs to that for engagement by the weights. In an alternative circuit arrangement the ignition switch and two sets of contacts are arranged in parallel, one set of contacts being closed when the engine throttle valve is closed, the other set being closed by the selection of the lower gear ratios, such as first and second gears of a four-speed gear-box. Specification 847,942 is referred to.