| 摘要 |
916,731. Change-speed control. BROWN INDUSTRIES Ltd., DAVID. Feb. 2, 1961 [Feb. 16, 1960], No. 5388/60. Class 80 (2). A vehicle transmission comprises fluid-pressure-operated forward and reverse drive clutches controlled by an inlet valve 13 operated by an engine driven pump 10 and an exhaust valve 21 operated by an output-driven pump 16, so that engagement of either clutch subsequent to disengagement of the other is prevented until the output shaft is stationary. Valve 21 is shown in the neutral position, and when the engine is running pump 10 moves the inlet valve 13 to the left against a spring 14 to supply oil to a duct 15 leading to the main control member by which it is diverted to either of passages 24, 25 in communication with the forward and reverse clutch actuators, respectively. With the vehicle moving forward pump 16 delivers to the sump pipe 18, a non-return valve 20 being closed so that pressure builds up to move valve 21 to the right and uncover the exhaust port 26 of the reverse clutch. To reverse, the main control is moved to the position to exhaust the forward clutch and as the vehicle comes to rest pump 16 ceases to operate so that valve 21 is centralized, cutting off both forward and reverse exhaust ports 26, 27 so that the reverse clutch is engaged. As pump 16 reverses oil is delivered to sump pipe 17 with pressure build-up to move valve 21 to the left and uncover the forward exhaust port 27. If the engine is not running valve 13 is in the position shown for a towing or rolling start. The pump 16 may be replaced by an electric generator energizing either of two coils operating valve 21 according to the direction of rotation.
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