| 摘要 |
PURPOSE: A hydraulic control system of an automatic transmission for a vehicle is provided to reduce driving loss of an oil pump by lowering line pressure in operating a damper clutch at 2-range and decreasing line pressure regardless of operation of the damper clutch over 3-range. CONSTITUTION: A hydraulic control system of an automatic transmission for a vehicle is composed of an oil pump(4) generating hydraulic pressure; a regulator valve(10) controlling hydraulic pressure; a reducing valve(14); and plural control valves receiving control pressure and switching the passage. A line pressure regulating unit is installed between a shift control valve, a damper clutch control valve and the reducing valve to switch the port of the regulator valve. Line pressure is decreased by returning hydraulic pressure from the oil pump to an oil pan partially.
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