A hydraulic pump/motor includes: a cylinder block rotating about a rotation axis; a piston in a cylinder bore; and a valve plate facing a cylinder port. The valve plate includes: a high pressure port through which oil discharged from the cylinder port flows; a low pressure port through which the oil to be sucked into the cylinder port flows; a region disposed between the high and low pressure ports in a circumferential direction of the rotation axis and including a top dead center position facing the cylinder port of the cylinder bore in which the piston moved to a top dead center is disposed; and a residual pressure release port between the top dead center position and the low pressure port in the region. The residual pressure release port includes first and second ports disposed at positions different from each other in the radial direction of the rotation axis.

The present invention relates to an axial piston pump (1,1) with inclined plate for pumping a liquid comprising: a head (20) in which there are at least partially a plurality of cylinders (25) in a number greater than three, with parallel central axes, a plurality of pistons (75), each one sliding inside a respective cylinder (25) of the plurality of cylinders (25) for pumping liquid, a housing seat of a suction valve (115) made in the head (20), a housing seat of a delivery valve (120) made in the head (20). The housing seat of the suction valve (115) and the housing seat of the delivery valve (120) are in direct fluid communication with each other via a rectilinear channel (155) made in the head, said channel in turn being in direct fluid communication with a cylinder (25) of the plurality of cylinders.

The present invention relates to an axial piston pump (1,1) with inclined plate for pumping a liquid comprising: a head (20) in which there are at least partially a plurality of cylinders (25) in a number greater than three, with parallel central axes, a plurality of pistons (75), each one sliding inside a respective cylinder (25) of the plurality of cylinders (25) for pumping liquid, a housing seat of a suction valve (115) made in the head (20), a housing seat of a delivery valve (120) made in the head (20). The housing seat of the suction valve (115) and the housing seat of the delivery valve (120) are in direct fluid communication with each other via a rectilinear channel (155) made in the head, said channel in turn being in direct fluid communication with a cylinder (25) of the plurality of cylinders.

The present disclosure relates to a piston assembly, the piston assembly comprising a cylinder extending along an axis and having an open axial end, a cap assembly closing the cylinder at its open axial end, wherein the cap assembly comprises an insertion portion received in the cylinder at its open axial end, and a piston axially movably disposed within the cylinder and partially received in the insertion portion of the cap assembly. The present disclosure further relates to a variable displacement hydraulic unit including said piston assembly.

The present disclosure relates to a zeroing device comprising a piston movable along an axis, at least one biasing member for biasing the piston along the axis, and an axially displaceable zeroing member limiting axial movement of the at least one biasing member. The present disclosure further relates to a variable displacement hydraulic unit including said zeroing device.

A control plate (18) of a hydraulic machine includes a body (21), an arrangement of openings (22, 23), and a contact face (24). Means should be provided to operate a hydraulic machine with a low noise level. To this end the body (21) is made of a flat plastic material.

A control plate (18) of a hydraulic machine includes a body (21), an arrangement of openings (22, 23), and a contact face (24). Means should be provided to operate a hydraulic machine with a low noise level. To this end the body (21) is made of a flat plastic material.

A hydrostatic piston engine comprises a housing with a cylinder drum with cylinder bores mounted rotatably therein. Each of the cylinder bores receives a working piston in a longitudinally displaceable manner, via which a hydrostatic working chamber is delimited by the cylinder bore. The hydrostatic working chamber has an opening on an outer surface of the cylinder drum by which, when the cylinder drum rotates, outlets of a high-pressure chamber and of a low-pressure chamber of the piston engine and a reversing surface arranged between the two outlets in the rotational direction can be passed over in alternating fashion. At least one pressurizing medium channel is provided which, on one hand, opens out in the reversing surface and, on the other, into a pressurizing medium trough of the piston engine.

Disclosed herein is a valve assembly for a variable swash plate compressor. Since an opening hole of a suction reed is enlarged toward a suction port of a valve plate and refrigerant is also introduced into a cylinder bore through the opening hole when the suction port is opened, performance of a compressor may be enhanced by an increase in flow rate.

A hydraulic pump assembly comprises a rotatable piston drum (20) with at least one centrifugal lever (23) pivotally attached thereto for radial movements between radial flanges (20) under the action of centrifugal force at rotation of the piston drum. The centrifugal lever (23) is arranged to control the position of a valve member, preferably a ball (22), at the opening end of a bore (21) in the piston drum (20). There is a defined friction surface (28; 32) between the lever (23) and one of the radial flanges (20), and there are spring means (29-31; 25, 33) for resiliently biasing the lever against said one of the flanges.