A hydrostatic piston machine has an adjustment element that is adjustable for varying a displacement volume, and a rotating cylinder part having a plurality of cylinder bores with pistons that are supported on the adjustment element and delimit a displacement chamber. Each displacement chamber is moved in an alternating manner by a connecting opening to overlap a low-pressure control opening situated on a low-pressure side of a stationary control part and a high-pressure control opening situated on a high-pressure side of the control part. Two switching regions are situated between the low-pressure control opening and the high-pressure control opening, the pistons changing direction at a dead center within the switching regions. The position of the adjustment element is determined from a pressure profile which is a function of the variable size of the displacement chambers in a switching region, the variable size depending on the position of the adjustment element.

A hydrostatic axial piston machine has a drive shaft penetrating a housing on either side. In this case, the mechanically weaker of the two shaft ends is strengthened by an undercut being eliminated, said undercut defining the minimum diameter of the shaft end and thus of the entire drive shaft. Instead, the strength of the relevant shaft end is increased by a displacement of a circular bearing surface for a rolling bearing radially outwardly and away from the rolling bearing. In this case, the circular bearing surface is displaced below a compression spring which clamps the cylinder drum against a distributor plate. The resulting spacing between the circular bearing surface and the rolling bearing remaining in place is bridged by a sleeve or by a ring. A concave rounded shaft shoulder is simply formed below the sleeve and/or the ring.

An axial piston pump may comprise a valve plate assembly including a plurality of valve plates rotatably disposed adjacent to each other and configured to control the flow of fluid between a piston chamber and inlet and outlet port passages. The piston pump may also comprise a swashplate arrangement that is capable of being angled in two different directions to be used in combination with the valve plate assembly. A fixed displacement axial piston pump may also comprise the valve plate assembly disclosed herein in which pressure transitions are facilitated in the same fashion, but without the variable of changing swashplate angles which control pump flow.

A bi-directional pump connected to a motor by a pair of supply/discharge lines; a regulator changes the bi-directional pump tilting angle; and a controller controls the regulator based on a turning signal outputted from a turning operation valve. At the turning acceleration, at which the signal increases, the controller calculates a motor flow rate passing through the motor and an instruction flow rate determined based on the turning signal. If the instruction flow rate is greater than a reference flow rate obtained by adding a predetermined value to the motor flow rate, the controller controls the regulator so the bi-directional pump tilting angle is adjusted to a tilting angle realizing the reference flow rate. If the instruction flow rate is not greater than the reference flow rate, the controller controls the regulator so the bi-directional pump tilting angle is adjusted to a tilting angle realizing the instruction flow rate.

An axial piston pump including a housing, a cylinder block, and a swash block. The cylinder block is rotatable within the housing about a vertical axis and includes an array of openings in the cylinder block distributed about the vertical axis and an array of pistons reciprocatably movable within the respective openings. The swash block is rotatable about an axis of rotation that is transverse to the vertical axis, and the degree of rotation is configured to control the extent of reciprocation of the pistons as the cylinder block rotates. The swash block has arc shape conical bearing surfaces tilted relative to the axis of rotation that are configured to guide movement of the swash block rotationally about the axis of rotation and prevent movement of the swash block axially along the axis of rotation.

A pump barrel (70) for use in a hydrostatic pump assembly includes a barrel body (88) defining a plurality of piston bores (84) that receive a plurality of pistons moveable within the bores, and a porting face (74) that defines a plurality of ports (72) in fluid communication with the piston bores and providing fluid flow paths into and out from the barrel body. Each port (72) has a leading edge surface and a trailing edge surface relative to a direction of rotation of the pump barrel, said leading and trailing edge surfaces being oriented in a first direction (along line 6-6) at non-right angles relative to the porting face (74). Each port (72) has an inner edge surface (80) and an outer edge surface (82) relative to a radial direction of the pump barrel, said inner and outer edge surfaces (80,82) being oriented in a second direction (along line 9-9) comprising a tilt angle (90,92) relative to the porting face (74) that is different from the angles in the first direction. A hydrostatic pump assembly incorporating such a pump barrel (70) is also disclosed.

A pump barrel (70) for use in a hydrostatic pump assembly includes a barrel body (88) defining a plurality of piston bores (84) that receive a plurality of pistons moveable within the bores, and a porting face (74) that defines a plurality of ports (72) in fluid communication with the piston bores and providing fluid flow paths into and out from the barrel body. Each port (72) has a leading edge surface and a trailing edge surface relative to a direction of rotation of the pump barrel, said leading and trailing edge surfaces being oriented in a first direction (along line 6-6) at non-right angles relative to the porting face (74). Each port (72) has an inner edge surface (80) and an outer edge surface (82) relative to a radial direction of the pump barrel, said inner and outer edge surfaces (80,82) being oriented in a second direction (along line 9-9) comprising a tilt angle (90,92) relative to the porting face (74) that is different from the angles in the first direction. A hydrostatic pump assembly incorporating such a pump barrel (70) is also disclosed.

A drive device incorporating a hydraulic pump having a swash plate. At least two structural ribs and skirting ribs are located on and extend along the length of the swash plate. A plurality of thrust ribs may be formed on an inner housing surface and adjacent to respective contact surfaces on the swash plate, the thrust ribs being located so that at least one, but fewer than all, of the ribs can be in contact with its respective contact surface on the swash plate at a time, permitting rotation while limiting axial movement of the swash plate. A trunnion shaft includes a free end disposed so as to be accessible from outside the housing through a bore formed therein, and a control arm having a shaft portion extends into and supports the distal free end of the trunnion shaft within the bore.

The invention relates to a rotary hydraulic machine which includes a casing (2) containing pistons actuated by an input shaft, said casing having a transverse front surface provided so as to engage with a mounting, and a transverse rear surface receiving a rear cover (4) supporting collectors connected to said pistons, the casing comprising side attachment tabs (30, 40) each having an axial bore (32) ending in a rear clamping surface, provided such as to receive an element for clamping said machine to the mounting, characterised in that at least one tab forms an axially elongate pad (40), the height of which is greater than half of the length of said casing included between the front and rear surfaces thereof.

A hydrostatic axial piston machine includes a double-acting actuating cylinder configured to adjust the piston displacement. The actuating cylinder has two actuating chambers that are connected to two spatially separated cartridge valves. The two cartridge valves are inserted obliquely into a wall section of the axial piston machine. The wall section on the one hand forms a wall of the housing of the axial piston machine and on the other hand forms a wall of the actuating cylinder.