Patent ID: 8677884

Claim:
A hydraulic pump/motor, comprising: a rotational shaft, both of whose ends are rotatably attached to a casing and an end cover closing an opening of the casing via a bearing; a cylinder block rotating together with the rotational shaft; a plurality of pistons fittedly inserted into a plurality of cylinder holes formed on the cylinder block so as to be able to reciprocate; a swash plate provided in the casing so as to be tilted relative to the rotational shaft to allow tip ends of the pistons to slide so as to be able to slidingly contact the swash plate; a valve plate that slidingly contacting a rear end face of the cylinder block, wherein the hydraulic pump/motor distributes oil into the cylinder holes through a port provided on the valve plate; a detected unit formed on an outer circumferential surface of the cylinder block; and a rotation sensor arranged in the casing in a state opposed to the detected unit for detecting the detected unit, wherein the rotation sensor is provided on a position corresponding to a position between a deepest portion of the cylinder hole and the rear end face of the cylinder block in an axial direction of the cylinder block.