Patent GB-536473-A (GB)
Title: Improvements in or relating to power transmission apparatus and motor vehicles employing such power transmission apparatus
IPC: B60K17/04
Filed: 1940-01-24
Abstract: 536,473. Variable-speed gearing; clutches; motor vehicles. SALISBURY CORPORATION. Jan. 24, 1940, No. 1469. Convention date, Jan. 30, 1939. [Class 80 (ii)] [Also in Group XXXI] In a power transmission for a motor vehicle an automatically actuated clutch couples the engine to the transmission apparatus only when the engine is rotating above a pre-determined idling speed, and the transmission speed ratio increases automatically to a higher gear as the speed of the vehicle increases. Means are provided to clutch the transmission mechanism to the engine so that the latter can be started up by giving a forward movement to the vehicle. The engine crankshaft 44 has keyed thereto a clutch casing 103 with a ramp 125. Loose on the shaft are pulley faces 110, 111 and a housing 117, the face 111 being connected to the housing 117 by springs 115, and the parts 110. 117 being attached to a loose hub 108. Springs 122, 123 urge the pulley face 111 towards pulley face 110. A circumferential spring 131 is enclosed between the ramp 125 and a pressure plate 127, and a friction plate 132 is keyed by teeth 135, 136 to the pulley half 110. The latter also has a row of inclined ratchet teeth 138 opposed by similar teeth on a cup member 140 containing a friction ring 143 pressed against the casing 103 by a spring 144. A belt 47 connects the pulley 110, 111 to pulley faces 153, 161 on a countershaft 48 which is connected by chain gearing to a wheel axis of the vehicle. The face 153 is fixed to the shaft 48. The face 161 is slidable axially and is movable tc the right, Fig. 6, by fingers 173 pivoted at 174 to a casing 164 and acted upon by springs 182, 183 and to the left by the centrifugal force of balls 191 which engage ramps 162, 187. Screws 185 adjust the springs 182, 183. In operation, when the engine is idling the spring 131 is in the radially innermost part of the ramp 125 and the clutch is disengaged. When the engine speed exceeds the idling speed the spring 131 expands under centrifugal force and moves the pressure plate 127 to the left, Fig. 6, to engage the clutch. The belt gearing is then in low gear. As the vehicle speed increases. the balls 191 move outwardly under centrifugal force to separate the pulley faces 153, 161 so that the belt gearing steadily approaches high gear position. To start up the engine when at rest, the vehicle is given a forward motion. The inclined parts of the ratchet teeth 138 engage the corresponding parts of the teeth 141 to press the friction ring 143 against the casing 103 and so rotate the engine. In a modification of the main friction clutch, the ramp 125 is inclined in two directions so that the clutch is disengaged for idling speed but engaged for speeds above and below the idling speed. In another modification for the same purpose two separate spring and two separate ramps are employed. In a modification of the expanding pulley on the countershaft 48 the distance apart of the faces 153, 161, is also controlled by a bellows acted upon by the vacuum in the engine. The transmission gear is shown applied to a three-wheeled vehicle and is encased in a housing 62 arranged above the single rear wheel 42. The driver's seat is positioned on the housing 62. The steering wheel 72 is mounted in a triangular frame 70 and has a pulley 81 with a cable 77 the two ends of which pass round guide pulleys 80, 82, and round a pulley 74 to which they are fixed at 78, 83. A pulley 75 is fixed to the pulley 74 and has a cable 76 round it, the ends of the cable being fixed to a tie rod 73 connecting the front wheels 33, 34. Brakes on the three wheels are connected by cables 84 to a bell crank 85 connected to a brake pedal 86. The vehicle has two carrying compartments 91, 92, with hinged covers 93, 94.