Abstract: A valve plate is used in a swash plate type motor including a motor shaft and a cylinder block in a motor housing and includes: a sliding supporting surface contacting a rear end surface of the cylinder block to support the cylinder block; a supporting surface that is a surface corresponding to and opposite to the sliding supporting surface; a central through hole through which the motor shaft penetrates; and a plurality of ports and formed around the central through hole as inlets and outlets of operating oil so as to penetrate the valve plate, and a cooling concave portion into which the operating oil flows is formed in a region except for the ports and on the supporting surface.

Abstract: A swash plate type hydraulic rotating machine includes: a rotating shaft; a valve plate; a swash plate; a cylinder block on the outside of the rotating shaft slidingly contacting the valve plate; cylinders provided in the cylinder block having axially movable pistons therein; shoes on a distal end of respective pistons; an annular keep plate between the swash plate and the cylinder block supporting the shoes having a plain bearing within the inner periphery of the keep plate, the plain bearing supporting the keep plate to push the keep plate toward the swash plate side; and set springs biasing the plain bearing and the cylinder block toward the opposite sides in the axial direction. The swash plate type hydraulic rotating machine is configured such that, when in an assembled state, a gap in the axial direction between the cylinder block and the plain bearing is 0 or a fine gap.

Abstract: A valve plate is used in a swash plate type motor including a motor shaft and a cylinder block in a motor housing and includes: a sliding supporting surface contacting a rear end surface of the cylinder block to support the cylinder block; a supporting surface that is a surface corresponding to and opposite to the sliding supporting surface; a central through hole through which the motor shaft penetrates; and a plurality of ports and formed around the central through hole as inlets and outlets of operating oil so as to penetrate the valve plate, and a cooling concave portion into which the operating oil flows is formed in a region except for the ports and on the supporting surface.

Abstract: The present invention provides a cooling structure of a cylinder block, the cooling structure being capable of improving a cooling performance of sliding surfaces. A cylinder block includes a plurality of cylinders, and pistons are respectively inserted into the cylinders through openings. Each of the pistons performs reciprocating sliding on a sliding surface which defines the cylinder. A plurality of cooling depressions are formed on an outer peripheral surface of the cylinder block. Each of the cooling depressions extends from a front end surface of the cylinder block on a dividing wall located between the two adjacent cylinders and is formed by reducing the thickness of the dividing wall so as to reduce a thickness of a portion between the sliding surface and the outer peripheral surface.