A hydraulic control circuit of a double-acting orientation cylinder to orient fan vanes of a turbojet engine, comprising an oil tank, a variable-displacement axial piston pump including a swash plate controlled by a double-acting control and compensation cylinder comprising a control chamber and a compensation chamber, the pump being supplied by the reservoir and having the outlet thereof configured to be able to be connected, via a supply pipe, to a second chamber of the orientation cylinder, a first chamber of the orientation cylinder being connected to the tank, the chambers of the control and compensation cylinder both being pressurised with a pressure corresponding to the outlet pressure of the pump, and wherein the control and compensation chambers are arranged to increase the tilt of the plate in order to increase the displacement of the pump when the pressurisation pressure of these chambers increases.

A mounting member for a hydraulic pump or other rotating kit for a hydraulic drive device includes a running surface having a pair of arcuate kidney ports formed thereon. The running surface also includes a plurality of pressure gradient grooves formed on the running surface, each pressure gradient groove having a proximal end adjacent to a respective one of the ends of one of the kidney ports and a distal end. The distal end of one of the pressure gradient grooves associated with one kidney port may overlap the distal end of a pressure gradient groove associated with the other kidney port. The distal end of at least one of the pressure gradient grooves is located outside the circumference of a pitch circle that passes through the center of each of the kidney ports. The distal end of at least one of the other pressure gradient grooves is located inside the circumference of the pitch circle.

A fluid pressure rotary machine includes a cylinder block that is fixed to a rotary shaft and includes a plurality of cylinder bores, a piston disposed to be free to slide in each cylinder bore such that a volume chamber is defined thereby, a swash plate that causes the piston to reciprocate such that the volume chamber expands and contracts, and a valve plate that slides against the cylinder block and includes an intake port and a discharge port communicating with the volume chamber. The valve plate includes a sliding surface formed to project in a spherical shape against the cylinder block. The cylinder block includes a sliding surface formed as an indentation corresponding to the shape of the sliding surface of the valve plate. A minute gap is formed between the sliding surface of the valve plate and the sliding surface of the cylinder block in an outer edge position.

An axial piston machine of swash plate design includes cylinder bores with respective longitudinal axes that are arranged at an acute angle with the rotational axis and that approach the rotational axis radially in the direction of their control plate-side ends. For each cylinder bore, a point of action of a resulting hydrostatic relieving force, which acts on the cylinder barrel, of the hydrostatic sliding bearing is spaced apart radially with regard to the rotational axis of the cylinder barrel further than a point of intersection of the longitudinal axis of the cylinder bore with the cylinder barrel-side bearing face of the hydrostatic sliding bearing.

A port plate for a swashplate type axial piston pump is described herein. The port plate includes an inlet port, a discharge port, and a first metering notch in fluidic communication via a first passage with a metering notch area adjustment valve configured to adjust the effective area of the metering notch. The first metering notch is disposed at a leading edge of one of the inlet port or the discharge port.

A valve plate for a fluid pump includes a body having a first surface and an oppositely disposed second surface. The body defines a first kidney slot that extends through the first and second surfaces and a second kidney slot that extends through the first and second surfaces. A first notch is disposed in the first surface of the body and extends outwardly from the first kidney slot in a direction toward the second kidney slot. A second notch is disposed in the first surface and extends outwardly from the first kidney slot in a direction toward the second kidney slot. The second notch is separated from the first notch.

A valve plate for a fluid pump includes a body having a first surface and an oppositely disposed second surface. The body defines a first kidney slot that extends through the first and second surfaces and a second kidney slot that extends through the first and second surfaces. A first notch is disposed in the first surface of the body and extends outwardly from the first kidney slot in a direction toward the second kidney slot. A second notch is disposed in the first surface and extends outwardly from the first kidney slot in a direction toward the second kidney slot. The second notch is separated from the first notch.

Hydraulic axial piston unit includes a rotatable cylinder block and a valve segment with two pressure ports. An IDC control port and an ODC control port are located on the valve segment in circumferential direction between the circumferential ends of the pressure ports such that a cylinder bore can be fluidly connected to the IDC control port or the ODC control port when the associated working piston is at or close to its inner dead center or outer dead center. The circumferential distance from the control ports to the pressure ports is smaller than the circumferential extension of the cylinder bores. A first and a second bypass line each connecting one of the control ports are provided with an adjustable orifice in the first bypass line, capable of continuously variably opening and closing the first bypass line in order to enable an adjustable fluid flow connection between the connected pressure port and the connected pressure port.

Hydraulic axial piston unit includes a rotatable cylinder block and a valve segment with two pressure ports. An IDC control port and an ODC control port are located on the valve segment in circumferential direction between the circumferential ends of the pressure ports such that a cylinder bore can be fluidly connected to the IDC control port or the ODC control port when the associated working piston is at or close to its inner dead center or outer dead center. The circumferential distance from the control ports to the pressure ports is smaller than the circumferential extension of the cylinder bores. A first and a second bypass line each connecting one of the control ports are provided with an adjustable orifice in the first bypass line, capable of continuously variably opening and closing the first bypass line in order to enable an adjustable fluid flow connection between the connected pressure port and the connected pressure port.

A hydrostatic axial piston machine is disclosed, in the housing of which a drive shaft is rotatably mounted about an axis of rotation. The housing comprises a pot-like housing part having a first abutment and a cover-like housing part having a second abutment. The two abutments are clamped against one another in a sealing manner. A first fitting pin is inserted precisely into a first fitting recess of the first abutment on the one hand and into a second fitting recess of the second abutment on the other hand. A second fitting pin is provided on a side opposite the axis of rotation, which is inserted precisely into a third fitting recess of the first abutment on the one hand and into a fourth fitting recess of the second abutment on the other hand. The second fitting recess has a radial widening relative to the axis of rotation, whereby the second fitting recess is a slotted hole and/or a fitting groove.