| 摘要 |
An automatic transmission has a frictionally engaging element, such as a low-and-reverse brake or the like, that is hydraulically actuated for assuming a certain gear position. A hydraulic control system for the transmission comprises a first hydraulic section which produces a line pressure; a solenoid which produces a solenoid pressure; a decompression control valve which receives the line pressure to produce an output pressure while using both the solenoid pressure and the output pressure as signal pressures; a switching valve interposed between the decompression control valve and the frictionally engaging element. The switching valve has a first position wherein the output pressure is fed to the frictionally engaging element and a second position wherein the line pressure is fed to the frictionally engaging element. The hydraulic control system further comprises a second hydraulic section that keeps the switching valve at the first position when a signal pressure applied thereto is lower than a predetermined switching pressure and turns the switching valve to the second position when the signal pressure becomes higher than the predetermined switching pressure.
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