| 摘要 |
PURPOSE: A hydraulic control system for an automatic transmission is provided to improve fuel consumption ratio by reducing load of an engine with lowering line pressure in the parking and neutral range and increase startability with reducing load of an oil pump. CONSTITUTION: A hydraulic control system for an automatic transmission comprises a torque converter(1) properly having torque change of driving force of the engine depending on the running condition of a vehicle; an oil pump(3) producing hydraulic pressure in accordance with driving of the engine; a pressure control unit controlling pressure, with geared with a manual valve(5) to make hydraulic pressure of the oil pump low by contrast with driving range line pressure in parking and neutral range; and a hydraulic distribution unit selectively supplying or exhausting hydraulic pressure to each friction element(9) to achieve hydraulic pressure transmitted through the manual valve to a predetermined gear level. Therefore, load of the engine is reduced and fuel consumption ratio is improved.
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