HYDRAULIC CIRCUIT FOR TRANSMISSION

PROBLEM TO BE SOLVED: To minimize a leakage of oil pressure transmitted to an oil pump from an external oil pressure supply source when the oil pump driven by an engine stops, without requiring a special check valve. SOLUTION: When a hydraulic actuator 19 is operated under the delivery pressure of a second oil pump OP2 because a first oil pump OP1 is out of operation, a pump shift valve 28 cuts off one discharge port 17B of the first oil pump OP1 from oil passages P4, P5. Discharge ports 17A to which oil pressure from the second oil pump OP2 is transmitted, are thereby reduced to one port to reduce the leakage of oil. At this time, a check valve (a first check valve) for preventing the supply of oil pressure to the first oil pump OP1 from the second oil pump OP2 is dispensed with to reduce the number of components. Furthermore, oil pressure from the second oil pump OP2 can be led to a regulator valve 21 without being intercepted by the check valve and regulated to a line pressure. COPYRIGHT: (C)2011,JPO&INPIT