A liquid pressure rotary machine in which a rotation delay of a retainer with respect to a cylinder block is reduced and contact of pistons placed between the retainer and the cylinder block with peripheral members is suppressed is provided. A piston pump includes a rotation shaft, a cylinder block, piston heads, piston rods, a retainer, a swash plate, and a tilt adjustment mechanism. When the tilt adjustment mechanism swings the swash plate, a discharge amount of the piston pump becomes variable. The retainer to be rotated together with the piston heads and the piston rods is supported by a retainer bushing provided in the rotation shaft. By engaging ball pins of the retainer bushing with spherical surface pin grooves of the retainer, the retainer and the retainer bushing are integrally rotatable about the center axis of the rotation shaft and the retainer is swung about the spherical surface center.

A liquid pressure rotary machine in which a rotation delay of a retainer with respect to a cylinder block is reduced and contact of pistons placed between the retainer and the cylinder block with peripheral members is suppressed is provided. A piston pump includes a rotation shaft, a cylinder block, piston heads, piston rods, a retainer, a swash plate, and a tilt adjustment mechanism. When the tilt adjustment mechanism swings the swash plate, a discharge amount of the piston pump becomes variable. The retainer to be rotated together with the piston heads and the piston rods is supported by a retainer bushing provided in the rotation shaft. By engaging ball pins of the retainer bushing with spherical surface pin grooves of the retainer, the retainer and the retainer bushing are integrally rotatable about the center axis of the rotation shaft and the retainer is swung about the spherical surface center.

Provided is a variable displacement pump which sucks and discharges a working fluid by moving a piston with a stroke in response to an inclination angle of a swash plate, the variable displacement pump including: a control piston which includes a columnar piston portion pressing the swash plate and adjusts the inclination angle of the swash plate between a maximal inclination angle in which a discharge capacity of the working fluid becomes maximal and a minimal inclination angle in which the discharge capacity of the working fluid becomes minimal; a piston accommodation portion which is formed in the housing and accommodates the piston portion; and a pressed portion which is disposed between the swash plate and the piston portion and is pressed toward the swash plate by the piston portion, in which when the inclination angle of the swash plate is an intermediate inclination angle in which the discharge capacity of the working fluid becomes an intermediate amount between the maximal amount and the minimal amount, a contact point between the piston portion and the pressed portion is located at a center portion including an axis center of the piston portion in an end surface on the side of the swash plate in the piston portion.

Provided is a variable displacement pump which sucks and discharges a working fluid by moving a piston with a stroke in response to an inclination angle of a swash plate, the variable displacement pump including: a control piston which includes a columnar piston portion pressing the swash plate and adjusts the inclination angle of the swash plate between a maximal inclination angle in which a discharge capacity of the working fluid becomes maximal and a minimal inclination angle in which the discharge capacity of the working fluid becomes minimal; a piston accommodation portion which is formed in the housing and accommodates the piston portion; and a pressed portion which is disposed between the swash plate and the piston portion and is pressed toward the swash plate by the piston portion, in which when the inclination angle of the swash plate is an intermediate inclination angle in which the discharge capacity of the working fluid becomes an intermediate amount between the maximal amount and the minimal amount, a contact point between the piston portion and the pressed portion is located at a center portion including an axis center of the piston portion in an end surface on the side of the swash plate in the piston portion.

A swash plate bearing is disclosed. The swash plate bearing may have an arcuate cage member having at least one flange and a plurality of rolling elements rotatably coupled to the at least one flange. A coupling seat extends laterally from the at least one flange, the coupling seat may have an insertion hole. A link member may be rotatably coupled to the cage member, the link member having a central portion positioned between a first terminal portion and a second terminal portion. A first stem connects the central portion to the first terminal portion and a second stem connects the central portion to the second terminal portion. The central portion is positioned in the insertion hole.

A swash plate bearing is disclosed. The swash plate bearing may have an arcuate cage member having at least one flange and a plurality of rolling elements rotatably coupled to the at least one flange. A coupling seat extends laterally from the at least one flange, the coupling seat may have an insertion hole. A link member may be rotatably coupled to the cage member, the link member having a central portion positioned between a first terminal portion and a second terminal portion. A first stem connects the central portion to the first terminal portion and a second stem connects the central portion to the second terminal portion. The central portion is positioned in the insertion hole.

The present invention relates to a hydraulic pump system including a variable displacement pump that generates an outlet pressure. The hydraulic pump system also includes a control system that decreases a displacement volume of the variable displacement pump in response to an increase in the outlet pressure and increases a displacement volume of the variable displacement pump in response to a decrease in the outlet pressure.

A hydraulic device comprises a housing, a shaft rotatable about a first axis of rotation and a flange. A plurality of cylindrical sleeves cooperate with a plurality of pistons on the flange to form compression chambers, wherein the cylindrical sleeves are rotatable about a second axis of rotation which intersects the first axis of rotation by an acute angle such that upon rotating the shaft the volumes of the compression chambers change. A barrel plate is rotatable about the second axis has a first side for supporting the cylindrical sleeves. An opposite second side is supported by a supporting surface of a plate-shaped face element which is fixed to the housing. The supporting surface lies in a first plane. The face element has a back side that lies in a second plane, which forms an angle with the first plane that is smaller than said acute angle.

A hydraulic device comprises a housing, a shaft rotatable about a first axis of rotation and a flange. A plurality of cylindrical sleeves cooperate with a plurality of pistons on the flange to form compression chambers, wherein the cylindrical sleeves are rotatable about a second axis of rotation which intersects the first axis of rotation by an acute angle such that upon rotating the shaft the volumes of the compression chambers change. A barrel plate is rotatable about the second axis has a first side for supporting the cylindrical sleeves. An opposite second side is supported by a supporting surface of a plate-shaped face element which is fixed to the housing. The supporting surface lies in a first plane. The face element has a back side that lies in a second plane, which forms an angle with the first plane that is smaller than said acute angle.

A hydraulic rotary machine configured to reduce sliding resistance of a reciprocating piston and to suppress a reduction in volumetric efficiency corresponding to an amount of leakage of hydraulic oil. A piston pump includes a rotor shaft, a cylinder block, a piston head, a piston rod, a retainer, a swash plate, and a tilt regulation mechanism. When the tilt regulation mechanism rocks the swash plate, the amount of discharge from the piston pump is variably changed. The retainer which rotates with both the piston head and the piston rod is supported by a retainer bush provided to the rotor shaft. The retainer sphere section of the retainer and the retainer bush sphere section of the retainer bush have spherical shapes having the same curvature. During the regulation of tilt, the retainer rocks while the retainer bush sphere section is in sliding contact with the retainer bush.