| 摘要 |
An automatic transmission has a low clutch that assumes its engaged condition at a plurality of lower gear positions of D-range and a high clutch that assumes its engaged condition at a plurality of higher gear positions of D-range, A hydraulic control system for the transmission comprises a hydraulic section that produces a line pressure; a solenoid valve that produces a solenoid pressure upon receiving a solenoid signal; a first pressure control valve that produces a first output pressure from the line pressure by using the solenoid pressure and the first output pressure as operation signal pressures, the first output pressure having a smaller gain with respect to the solenoid pressure; a second pressure control valve that produces a second output pressure from the line pressure by using the solenoid pressure and the second output pressure as operation signal pressures, the second output pressure having a larger gain with respect to the solenoid pressure; and a switching valve that selectively assumes a first position to feed the low clutch with the first output pressure when the engagement of said low clutch brings about a higher gear position that needs a smaller torque contribution, and a second position to feed the low clutch with the second output pressure when the engagement of low clutch brings about a lower gear position that needs a larger torque contribution. The switching movement of the switching valve is effected by a high clutch pressure applied to the high clutch.
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