| 摘要 |
PURPOSE:To always secure necessary clutch pressure without any influence of line pressure control by controlling a clutch of a forward-backward switching device and a brake by individual hydraulic control systems having a sub oil pump. CONSTITUTION:A main oil pump 70 and a sub oil pump 72 are operated by starting of an engine to generate oil pressure, and a high line pressure governed by a line pressure control valve 100 is generated in a main oil pump side oil path 81, which is supplied to a cylinder 47 to set a low-speed step. On the other hand, a low working pressure governed by two relief valves 150, 160 is generated in sub oil pump side oil paths 140, 85, and the thus generated reducing pressure is conducted to each solenoid valve for control. The working pressure is conducted to a transfer control valve 130 to generate a clutch pressure, which is supplied to a transfer clutch 63 to transmit a torque.
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