PROBLEM TO BE SOLVED: To provide a variable displacement hydraulic pump satisfactorily controlling a displacement variable mechanism even in a low pressure region and having a stable state on both the large displacement side and the small displacement side.;SOLUTION: The variable displacement pump has a switching valve which forms a first connection for connecting a pressure receiving part to a low pressure side flow passage to reduce pilot pressure when a displacement variable mechanism for varying a discharge volume per unit revolution of a pump mechanism for sucking and discharging liquid with rotation driving by a prime mover by mechanically shifting in accordance with increase and decrease of the pilot pressure acting on the pressure receiving part is shifted to the large displacement side, and which forms a second circuit connection for introducing own discharge pressure of the pump mechanism to the pressure receiving part as the pilot pressure when the displacement variable mechanism is shifted to the small displacement side. A liquid outflow blocking means is equipped for blocking outflow of the liquid from the pressure receiving part side to a discharge side of the pump mechanism to seal off the pilot pressure acting on the pressure receiving part when the switching valve forms the second circuit connection.;COPYRIGHT: (C)2006,JPO&NCIPI
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