Patent GB-455361-A (GB)
Title: Improvements in variable speed power transmissions for vehicles
IPC: F16H61/00
Filed: 1935-04-15
Abstract: 455,361. Controlling change speed gearing and clutches. ABBEY, A., 111, Hatton Garden, London.-(Velo Automishun Corporation; 15, Exchange Place, Jersey City, New. Jersey, U.S.A.) April 15, 1935, No. 11659. [Class 80 (ii)] [See also Group XXIX] Change-speed shifter-elements 21c and 22c, Fig. 2 for first-speed and reverse, and second- and high-speeds respectively, are separately operated by pairs of pneumatic power-cylinders 21, 21 and 22, 22 respectively, and the power-cylinders 21 automatically operate a valve 21d which acts somewhat as a fluid interlock and ensures that, during a change from first to second speeds, the power-cylinders 21 are first energized to change from first speed to neutral, in which position the valve 21d energizes the power-cylinders 22 for change from neutral to second-speed. The working- fluid is engine-suction, controlled by a sliding distributer-valve 23, operated only automatically by a driven-shaft centrifugal governor 45, Fig. 3, a manual valve 77, Fig. 2, being provided for selecting first speed or reverse, such manual valve being supplied with enginesuction through the governor-controlled valve 23, which latter cuts off the supply above a speed of four or five miles per hour, thereby rendering the manual valve 77 ineffective to energize the reverse shift device at all speeds above that mentioned. The fluid supply to the manual valve 77 also passes through a valve 50, opened by manual depression of the main-clutch pedal, so that forward or reverse selection cannot be rendered effective until the clutch is disengaged. During an automatic change, the main-clutch is automatically disengaged and the engine throttled. There is also an interconnection with the service-brake, whereby the gear is automatically neutralized when the vehicle is braked to a standstill. Such interconnections are described in detail below. In order to avoid the bulk of large gear-shifting cylinders, two double-acting cylinders 21 act together on the shifter-element 21c for low-speed and reverse, whilst two similar cylinders 22 act on the second- and high-speed shifter element 22c, the individual pistons of each pair being rigidly connected together. Single cylinders may alternatively be used. Engine-suction, from an inlet-pipe 19, is directed to the appropriate sides of the cylinders 21, 22, by the sliding distributer-valve 23, loaded in one direction by a spring 35, and in the other by the governor 45 on the driven shaft 7a, the valve serving also to vent the idle side of the cylinders 22. Moving with the shifter-element 22c is a valve 22d, which serves to connect either side of the cylinders 22 alternately with vent-conduits 65, 66, normally closed by a valve 52, which is yieldingly connected with the service-brake pedal, depression of which vents both conduits 65, 66, and simultaneously energizes a suctionconduit 67 which, when the governor allows the distributing-valve 23 to return to its position of rest, communicates with central ports 67<1> in the shifter-cylinders, thereby neutralizing the gear. In moving from the low-speed position (at the right of Fig. 2) to neutral, the side 56<1> of the cylinders 21 is neutralized by an atmospheric vent 71, opened by a latch connection with the piston and released when the latter reaches neutral. Means for disengaging the main-clutch 17, Fig. 6, and, throttling the engine during a change, comprises a suction-cylinder 118, acting on the clutch-pedal 17, which latter acts mechanically on the engine-throttle 137 through a lever 139. The power-cylinder 118 is connected with the engine-suction line 19, through a valve 120<1>, opened by movement in either direction, of a piston 133 in a doubleacting cylinder 59 connected to opposite ends of the shifter-cylinders 22 for second- and-high speeds. The valve 120<1> always opens in the same direction, irrespective of the direction of movement of the piston, an enlargement 131 of which acts alternately on a pair of trip-latches 124, 126 connected by a lever 123 and a spring 129. Before the piston 133 reaches the end of its travel, the latch 124 strikes a stop 130, thereby freeing the piston, whilst a detent 144 springs up to hold the lever 123 in the valve-open position. At the end of the movement, a collar 143 on the throttle-rod 140, disengages the detent 144 and allows the clutch to re-engage, a spring 137<1> then opening the throttle. For complete manual operation, the suction is cut off at 20 and during a gear-shift, all the by shifter cylinders are vented to atmosphere a foot-operated valve 107, Fig. 2. The changespeed gear, which is of the conventional sliding-wheel type, can then be operated by a readily attachable conventional ballmounted lever, normally carried as an accessory in the vehicle. In a modification, the clutch-control valve 120a, Fig. 29, is opened by release of the accelerator-pedal 156, but, in order to prevent the engine racing with the clutch disengaged, an engine-driven centrifugal governor 158 acts on a collar 160 and keeps the clutch-control valve closed until the engine-speed falls even though the accelerator-pedal has been released. For a rapid change, the clutch-pedal 17a can be manually operated to open the valve 120a through a lever 161, without waiting for the engine to slow down. The clutch-pedal operates a valve 50a, energizing the change-speed power devices.