A radial piston device includes a housing, a pintle attached to the housing and having a pintle shaft, a rotor rotatably mounted on the pintle shaft and having cylinders, pistons displaceably received in the cylinders, and a drive shaft coupled to the rotor and rotatably supported within the housing. The radial piston device includes mechanisms for reducing a pressure loss of hydraulic fluid flowing into the pintle shaft.

The present invention relates to a hydraulic device (10) with radial pistons, comprising: a shaft (12) arranged along an axis (1); a cover (13) forming a casing element, the cover and the shaft being free to rotate with respect to one another; a distribution assembly comprising: a multi-lobe cam (14); a cylinder block (15); a distributor (16) configured to exert a thrust force (P) against the cylinder block (15) along the axis (11) of the shaft; an assembly (22) of mechanical bearings comprising at least one mechanical bearing (22a) mounted in radial contact between the cover (13) and shaft (12), said assembly being configured to take up the thrust force (P) exerted by the distributor (16); and a radial contact ball bearing mounted in radial contact between the cover (13) and the shaft (12).

The device has an internal distributor to be disposed in a casing portion (10A), and has a body (15) that has an outside axial face (15B) provided with two grooves (17, 19) respectively for feed and for discharge. The distributor has distribution ducts (23A, 23B, 23C) that open out in a distribution radial face and a cylinder capacity selector that has a slide (50) suitable for being moved in an axial bore (53) for connecting the distribution ducts to one or the other of the grooves. The device further has a control chamber (52) provided between a first end wall (15) of the bore and the first end (50A) of the slide, and an opposing spring (55) disposed in a return chamber (52) situated at the second end (53) of the bore and closed, at the end closer to the distribution face (15A), by a second end wall (55) of the distributor.

The device has an internal distributor to be disposed in a casing portion (10A), and has a body (15) that has an outside axial face (15B) provided with two grooves (17, 19) respectively for feed and for discharge. The distributor has distribution ducts (23A, 23B, 23C) that open out in a distribution radial face and a cylinder capacity selector that has a slide (50) suitable for being moved in an axial bore (53) for connecting the distribution ducts to one or the other of the grooves. The device further has a control chamber (52) provided between a first end wall (15) of the bore and the first end (50A) of the slide, and an opposing spring (55) disposed in a return chamber (52) situated at the second end (53) of the bore and closed, at the end closer to the distribution face (15A), by a second end wall (55) of the distributor.

The hydraulic apparatus is set so that the ratio of the pressure-receiving area of the respective bottom oil chambers of the boom cylinder, the arm cylinder and the bucket cylinder to the pressure-receiving area of the respective rod oil chambers matches the ratio of the extruded volume drawn into or discharged from the bottom oil chambers per single rotation by the respective extrusion members of the first hydraulic pump motor, the second hydraulic pump motor and the third hydraulic pump motor to the volume discharged from or drawn into the rod oil chambers.

Hydrostatic radial piston unit comprising a front case part accommodating a drive shaft via shaft bearing means so that the drive shaft can rotate around a central axis relative to the front case part. A rear case part is attached on one side to the front case part and closed on another side in order to define an internal volume. A cylinder block is disposed in the internal volume and attached to the drive shaft in a torque proof manner. Axially disposed timing holes in the cylinder block connect radially oriented working volumes in the cylinder block with a cylinder block front face that is arranged perpendicularly to the central axis and faces away from the front case part. Integrally within the rear case part internal annular flow passages are formed and are connected to an inlet and an outlet of the radial piston unit and running basically in circumferential direction around the central axis. Internal distribution conducts configured to hydraulically connect the internal annular flow passages with the cylinder block timing holes are integrally formed within the rear case part, too.

A hydrostatic radial piston unit of the cam-lobe type of construction including a shaft defining a rotational axis of the hydrostatic radial piston unit. The shaft extends with a front end region from a non-rotary, stationary rear casing to a front casing. Within the front casing a cylinder block is housed and fixed in a torque-proof connection to the front end region of the shaft. In the cylinder block radially reciprocating working pistons are disposed in radially oriented cylinder bores to and from which cylinder bores hydraulic fluid can be conducted by means of a distributor. The distributor is arranged rotationally fixed with respect to the front casing and rotationally free relative to the shaft. A circumferential cam-lobe surface with which the working pistons can interact, is formed integrally with the front casing on its radial inner side.

The device comprises a casing portion that has an open axial end and that has two main holes, respectively for fluid feed and for fluid discharge. Said holes open out in an inside axial face of the casing portion, respectively via a first main orifice and via a second main orifice that are disposed in succession in the direction going away from the open axial end. The inside axial face has first, second, and third sealing inside bearing surface arrangements, respectively situated between the open axial end and the first main orifice, between the two main orifices, and beyond the second main orifice. At least two of the three arrangements are staggered inside arrangements, each of which comprises two axial bearing surfaces that are staggered relative to each other, and that are separated by a shoulder facing towards the open axial end.

The device comprises a casing portion that has an open axial end and that has two main holes, respectively for fluid feed and for fluid discharge. Said holes open out in an inside axial face of the casing portion, respectively via a first main orifice and via a second main orifice that are disposed in succession in the direction going away from the open axial end. The inside axial face has first, second, and third sealing inside bearing surface arrangements, respectively situated between the open axial end and the first main orifice, between the two main orifices, and beyond the second main orifice. At least two of the three arrangements are staggered inside arrangements, each of which comprises two axial bearing surfaces that are staggered relative to each other, and that are separated by a shoulder facing towards the open axial end.

An axial piston machine may include a rotor mounted rotatably in a housing. The axial piston machine may also include a plurality of cylinders in which a plurality of pistons are disposed such that the plurality of pistons are translationally movable. The plurality of cylinders may be arranged in a ring-like manner around the rotor. Further, the axial piston machine may include a starter device configured to exert a pulse-like torque on the rotor to initiate a starting operation. The starter device may be couplable to the rotor.