GB622786A - Improvements relating to power transmission mechanism for motor vehicles - Google Patents

Abstract

622,786. Change-speed gear; clutches. MORRIS MOTORS, Ltd., MERRITT, H. E., and FOWERAKER, D. B. April 9, 1947, No. 9386. [Class 80 (ii)] In a change-speed gear in which a two-speed gearbox, arranged for a kick-down shift, is used in conjunction with a main gearbox, two centrifugal clutches operate the twospeed gear which has a one-way coupling in the low speed path, to give direct drive when both clutches are engaged and low speed when one clutch is disengaged. A two-speed gear 1 having two input shafts 3, 4 driven from the two centrifugal clutches 25, 24 provides a direct drive, through the. shaft 4, and a low-speed drive through the shaft 3, gears 5, 6, freewheel 13 and gears 12, 11 to the shaft 4 which also constitutes the input shaft of a conventional main gearbox. The driven plate of the clutch 24 which is splined to the shaft 4 is located oetween a face of the engine fivwheel 27 and a front driving plate 28 slidably mounted on three studs 29 fixed to the flywheel. The driven plate of the clutch 25 is located between the plate 28 and a rear driving plate 32 acted upon by clutch springs 34 carried by a spring carrier plate 33, the latter being slidably carried on bolts 35, disposed within three of the springs 34 and having heads which engage with the carrier plate 33. The carrier plate is moved axially for clutch engagement by the outward movement of three centrifugal weights 36, pivoted on bolts 37 which interconnect the rear driving plate and a front carrier plate 30, acting through the levers 40 pivoted on an end plate 42 and having their ends 43 engaging the spring carrier plate 33. When the speed of rotation of the clutch has become low enough for disengagement, the springs 34 move back the plate 33 to the limit of the bolt heads, and then the pull-off springs 46 move the rear driving plate 32 to disengage the clutches, the springs 47, 48 holding the front driving plate 28 equidistant from the flywheel and the rear plate 32. A manual clutch control for disengagement is provided by the thrust block 51 movedaxially by a fork 52 on a shaft 71 to engage the inner end of three levers 49 pivoted on pins in the bolts 55 carried by the end plate 42. Between the fulcrum and its outer end, each lever bears on a bridge piece 57, carried by studs which pass with clearance through the rear driving plate and are secured in the front driving plate, such that initial movement. of the fork 52 disengages the clutch 24. At their ends the levers bear on the plate 30 such that continued movement of the fork 52 results in complete disengagement of the clutches. To enable the vehicle to be started by towing or pushing, spring controlled centrifugal latches 60, in accordance with Specification 483,102, are fitted. Excess travel of the accelerator -pedal 63 causes the spring-loaded plunger 64 to rock the lever 65 and so, through the linkwork 66, 67, 68, key 72 in the elongated slot 73, shaft 70 and the levers 75, 76 to move the fork 52 to disengage the clutch 24 aided by the servo-spring 81 which assists engagement and disengagement of the clutches by toggling over the lever 80. A lost motion connection in the form of a chain 78 co-operates with the key and slot connection 72, 73 to allow partial movement of the fork 52 by the accelerator pedal 63 and full movement of the fork by the main clutch pedal, 74 without interference with the alternate pedals. The kick-down low speed is held engaged by a latch 84 engaging the end of the lever 65 ; substantial movement of the pedal 63 in the direction of its release moves the lever arm 87 and thence rod 86 to press an abutment 90 on the latch plate, thus releasing the lever 65. A torsion spring 94 takes up slack in the clutch lever and thrust block 51.