A variable displacement vane pump includes a biasing element for urging the control ring toward a first position that corresponds to a maximum volumetric capacity of the pump. Fluid pressure within a control chamber urges the control ring toward the second position. A feedback path is in communication with a fluid outlet of the pump for supplying a pressurized fluid. A first supply path provides the pressurized fluid to the fluid inlet. A second supply path provides the pressurized fluid to the control chamber. A valve controls flow of the pressurized fluid via the second supply path by moving between a fully open position and a fully closed position in which flow of the pressurized fluid along the second supply path is prevented by the valve. Moving the valve from the open position to the closed position increases the fluid pressure within the control chamber.

A variable displacement vane pump includes a biasing element for urging the control ring toward a first position that corresponds to a maximum volumetric capacity of the pump. Fluid pressure within a control chamber urges the control ring toward the second position. A feedback path is in communication with a fluid outlet of the pump for supplying a pressurized fluid. A first supply path provides the pressurized to the fluid inlet. A second supply path provides the pressurized fluid to the control chamber. A valve controls flow of the pressurized fluid via the second supply path by moving between a fully open position and a fully closed position in which flow of the pressurized fluid of along the second supply path is prevented by the valve. Moving the valve from the open position to the closed position increases the fluid pressure within the control chamber.

A variable capacity type oil pump, which is driven by an engine, supplies hydraulic pressure to a hydraulic control circuit of an automatic transmission. A range switch mechanism, which includes a motor as a motive power source, switches a shift range of the automatic transmission. Further, a switch operation mechanism, which switches a discharge amount of the oil pump, is driven by the motor of the range switch mechanism. In this case, an operative position of the switch operation mechanism is switched by the motor according to an input rotation speed of the oil pump, thereby switching the discharge amount of the oil pump. Accordingly, the motor of the range switch mechanism is used to drive the switch operation mechanism to switch the discharge amount of the oil pump, and thus a motive power source dedicated to changing the discharge amount of the oil pump is not needed.