A nitriding layer (13) is formed on the front surface side of a base material of a cylinder block (7) including an opening side end surface (7B) and each cylinder hole (12). Then, a piston sliding surface (12A) of each cylinder hole (12) is formed as a compound layer-removed hole (17) by removing a compound layer (16) that is located on the front surface side of the nitriding layer (13) by using polishing means such as, for example, honing and so forth. Further, a compound layer-removed surface (18) is formed on a part (A) where a compound layer-removed hole (17) and a cylinder inlet side tapered surface (12B) of each cylinder hole (12) intersect by using the polishing means such as, for example, the honing and so forth. This compound layer-removed surface (18) is formed as a tapered-state inclined surface of an angle α.

A rotary type valve plate compressor may include a shaft, a housing through which the shaft passes, a plurality of cylinders mounted in the housing, a piston received in the cylinder and to be moved forward and rearward in response to rotational operation of a swash plate, and a rotary type valve plate to receive a rotational force of the shaft and to open and close a refrigerant passage hole through which refrigerant passes, based on a phase of the piston.

A rotary type valve plate compressor may include a shaft, a housing through which the shaft passes, a plurality of cylinders mounted in the housing, a piston received in the cylinder and to be moved forward and rearward in response to rotational operation of a swash plate, and a rotary type valve plate to receive a rotational force of the shaft and to open and close a refrigerant passage hole through which refrigerant passes, based on a phase of the piston.

An axial piston machine of oblique axis design has a pivot angle that is adjustable via a set piston and a control valve and includes a first valve slide that is linearly movable relative to a first valve axis and is connected at two opposite ends to a first or a second fluid port. The first valve slide has a central region that defines a control point at which the lower of pressures at the first and second fluid ports act. The control point is connected via a fixed first throttle and a second throttle to a housing interior. A second valve slide that is linearly movable relative to a second valve axis is configured to adjust the second throttle. The first valve axis is arranged between the set piston and the control valve or a region of the control valve and is oriented transverse to the adjusting axis.

A bent-axis axial-piston hydraulic machine may have a cylinder block being movable circumferentially about a first rotation axis. The machine may also have a transmission shaft which is functionally associated with the cylinder block and which can rotate about a transmission axis incident on the rotation axis. The machine may also have a distributor, and a device for angular offsetting which is associated with the distributor to rotate the distributor to cause a variation of effective cubic capacity while a geometric cubic capacity of the machine remains constant. The corresponding method for adjusting the capacity of a bent-axis axial piston hydraulic machine is also disclosed.

An axial piston machine of oblique axis design has a pivot angle that is adjustable via a set piston and a control valve and includes a first valve slide that is linearly movable relative to a first valve axis and is connected at two opposite ends to a first or a second fluid port. The first valve slide has a central region that defines a control point at which the lower of pressures at the first and second fluid ports act. The control point is connected via a fixed first throttle and a second throttle to a housing interior. A second valve slide that is linearly movable relative to a second valve axis is configured to adjust the second throttle. The first valve axis is arranged between the set piston and the control valve or a region of the control valve and is oriented transverse to the adjusting axis.

An axial hydraulic pump-motor, in which a cylinder block having a plurality of cylinder bores on a valve plate having a high-pressure side port and a low-pressure side port for controlling an amount of reciprocation of a piston in each of the cylinder bores, the hydraulic pump-motor includes: a residual pressure release port provided on the valve plate and communicating until the cylinder bore on a top dead center side communicates with the low-pressure side port; a residual pressure acquisition portion obtaining a value of a residual pressure in the cylinder bore on the top dead center side; and a directional switching valve switching a flow path between the residual pressure release port and an hydraulic oil tank and a flow path between the residual pressure release port and the low-pressure side port.

An axial hydraulic pump-motor, in which a cylinder block having a plurality of cylinder bores on a valve plate having a high-pressure side port and a low-pressure side port for controlling an amount of reciprocation of a piston in each of the cylinder bores, the hydraulic pump-motor includes: a residual pressure release port provided on the valve plate and communicating until the cylinder bore on a top dead center side communicates with the low-pressure side port; a residual pressure acquisition portion obtaining a value of a residual pressure in the cylinder bore on the top dead center side; and a directional switching valve switching a flow path between the residual pressure release port and an hydraulic oil tank and a flow path between the residual pressure release port and the low-pressure side port.

A rotary type valve plate compressor may include a shaft, a housing through which the shaft passes, a plurality of cylinders mounted in the housing, a piston received in the cylinder and to be moved forward and rearward in response to rotational operation of a swash plate, and a rotary type valve plate to receive a rotational force of the shaft and to open and close a refrigerant passage hole through which refrigerant passes, based on a phase of the piston.

An axial piston pump, particularly for hydraulic systems, includes a cylinder drum (1) rotationally driven about an axis (15) in a pump housing (7). Piston cylinder units are arranged in the drum in a circle at an offset. Pistons (21) are at least indirectly supported on a swashplate (3) by their actuation end (31) accessible outside the cylinder drum (1). Between the swept volumes (19) of the piston cylinder units and a stationary fluid inlet and stationary fluid outlet of the pump housing (7), a control device (23) is arranged that has fluid channels (25, 26) for the targeted transfer of fluid from the fluid inlet into the swept volumes (19) and from the swept volumes (19) to the fluid outlet. At least one pressure compensation channel (28, 30) is provided in the control device (23), between the fluid channels (25, 26), to build or release fluid pressure in the swept volumes (19) in a targeted manner.