| 摘要 |
PURPOSE:To prevent the drop in a line pressure at the time of sudden stoppage of a vehicle so that it can be responsively increased and restored by adding an oil pressure chamber for operating the spool of a pressure regulating valve toward the drain-port closing side, and supplying a pitot pressure to this oil pressure chamber via at least a check valve. CONSTITUTION:If the number of revolutions of an engine suddenly drops at the time of sudden braking, the pitot pressure and the pump oil pressure drops. Then, in a pressure regulating valve 60, while the oil pressure in the port 61a on the one side of a subland 65 at the end part of a spool 62 is nearly zero, in the oil pressure chamber 66 on the other side an oil pressure remains by the action of a check valve 13, and therefore the remaining pressure in the oil pressure chamber 65 immediately shifts the spool 62 to the closing side of a drain port 61d even if the load of a spring 64 is small. Thus, the drop in a line pressure can be prevented, and the line pressure can be responsively increased and restored.
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