A hydraulic motor for vehicle wheel includes a hydrodynamic element, a reaction element, an oil distributor rotating as one with the reaction element, and a brake mounted between the two elements to oppose the rotational movement. The hydrodynamic element has a flange that surrounds the oil distributor. On its radially exterior face, it has means for rotationally coupling with the rotary discs of the brake. The brake is thus positioned around the distributor.

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).

A hydraulic radial piston device includes a housing, a pintle having a pintle shaft, a rotor mounted on the pintle shaft and defining a plurality of cylinders, and a plurality of pistons displaceable in the cylinders. The radial piston device further includes a piston ring that provides an interface for the pistons. The radial piston device includes various configurations for improving the performance and efficiency of the device.

A hydraulic radial piston device includes a housing, a pintle having a pintle shaft, a rotor mounted on the pintle shaft and defining a plurality of cylinders, and a plurality of pistons displaceable in the cylinders. The radial piston device further includes a piston ring that provides an interface for the pistons. The radial piston device includes various configurations for improving the performance and efficiency of the device.

A hydraulic radial piston device includes a housing, a pintle having a pintle shaft, a rotor mounted on the pintle shaft and defining a plurality of cylinders, and a plurality of pistons displaceable in the cylinders. The radial piston device further includes a piston ring that provides an interface for the pistons. The radial piston device includes various configurations for improving the performance and efficiency of the device.

The hydraulic machine includes a cam and a cylinder block with pistons co-operating with cam lobes, each of which has two ramps extending between top and bottom dead center arcs. The cylinders are connected in alternation to a feed and to a discharge, in sequences separated by switchover stages including an isolation stage during which they are isolated relative to the feed and discharge main ducts. The angular position of the start or of the end of at least one first isolation stage relative to the corresponding dead center arc is different from the angular position of the start or of the end of at least one second isolation stage relative to its corresponding dead center arc, both of these dead center arcs being top dead center arcs or both of them being bottom dead center arcs.

A device for hydraulically operating a drive wheel of a wellbore tractor has, in certain embodiments, at least one cam and a rotatable assembly arranged to be rotatable with respect to the cam about an axis of rotation. The rotatable assembly has at least one piston. The device also has a chamber and at least one supply port for supplying hydraulic fluid from the chamber to the piston for energizing the piston, the supply port being arranged to be moved between first and second positions relative to the cam. In the first position, the piston can connect to the supply port and be energized to impart force against the cam for producing forward rotation of the assembly. In the second position, the piston can connect to the supply port and be energized to impart force against the cam for producing reverse rotation of the assembly. Related distributor assembly, wellbore tractor, and method are also described.

A device for hydraulically operating a drive wheel of a wellbore tractor has, in certain embodiments, at least one cam and a rotatable assembly arranged to be rotatable with respect to the cam about an axis of rotation. The rotatable assembly has at least one piston. The device also has a chamber and at least one supply port for supplying hydraulic fluid from the chamber to the piston for energizing the piston, the supply port being arranged to be moved between first and second positions relative to the cam. In the first position, the piston can connect to the supply port and be energized to impart force against the cam for producing forward rotation of the assembly. In the second position, the piston can connect to the supply port and be energized to impart force against the cam for producing reverse rotation of the assembly. Related distributor assembly, wellbore tractor, and method are also described.

The devices comprises a distributor (16) that presents distribution ducts opening out into a radial distribution face (16A), and a distributor-counterpart engaged in each other in such a manner that two main enclosures (18, 20) are provided between their opposite axially-extending faces. The device comprises a cylinder-capacity selector comprising two slides (24, 26) arranged after the other in a bore (22) of the element engaged in the other, to which are connected the main enclosures (18, 20) and at least some of the distribution ducts (30, 31). The slides are able to adopt at least three distinct configurations establishing different connections between the main ducts (18, 20) and the distribution ducts via the main enclosures, in order to be able to obtain at least three distinct operating cylinder capacities.

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.