A hydraulic radial piston device is provided with a mechanism for reducing pressure pulsations and providing a smooth pressure transition throughout different displacement operations. In certain examples, the hydraulic radial piston device is configured to maintain an amount of precompression and an amount of decompression of hydraulic fluid trapped in a cylinder chamber to be consistent, respectively, throughout different displacement operations.

A hydraulic radial piston device is provided with a mechanism for reducing pressure pulsations and providing a smooth pressure transition throughout different displacement operations. In certain examples, the hydraulic radial piston device is configured to maintain an amount of precompression and an amount of decompression of hydraulic fluid trapped in a cylinder chamber to be consistent, respectively, throughout different displacement operations.

A piston unit includes a piston which has a rolling element seat configured to rotatably support a rolling element. The rolling element seat has a bearing surface with a surface coating composed of a polymer compound or with a ceramic surface coating.

A piston unit includes a piston which has a rolling element seat configured to rotatably support a rolling element. The rolling element seat has a bearing surface with a surface coating composed of a polymer compound or with a ceramic surface coating.

The pump can have a support having a guide extending around an axis, a radial position of the guide relative the axis varying around the axis, and a first oil passage formed in the support; a rotary assembly mounted to the support via support bearings, and rotatable around the axis, the rotary assembly having a second oil passage and a cylinder, the cylinder extending radially relative the axis, an inlet port fluidly connecting the first oil passage to the cylinder, and an outlet port fluidly connecting the cylinder to the second oil passage, and a piston slidingly mounted in the cylinder, a radially-outer end of the piston further slidingly engaged with the guide.

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 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.

A radial piston device includes a housing (102), a pintle (110) attached to the housing (102) and having a pintle shaft (112), a rotor (130) rotatably mounted on the pintle shaft (112) and having cylinders (132), pistons (150) displaceably received in the cylinders (132), and a drive shaft (190) coupled to the rotor (130) and rotatably supported within the housing (102). The rotor (130) is made with two parts, such as a rotor body (250) and a rotor insert (252) received into the rotor body (250).

A pump having two pistons placed in a rotor, situated in a stator forming two opposite parallel eccentric pumping chambers having at least one inlet port through which the fluid is drawn into at least one of the pumping chambers during the filling movement of at least one of the pistons and, subsequently, expelled from at least one of the pumping chambers, during the emptying movement of at least one of the pistons, to at least one outlet port, characterized by an inlet cavity in connection with the inlet port, an outlet cavity in connection with the outlet port and two port changeover transition zones situated between each side of the cavities.

To provide a radial piston pump capable of displacement control without using an electronic control valve. For achieving the above object, the radial piston pump includes: a first cam circumferentially varying in radius on an inner circumferential side or outer circumferential side of the cam in a continuous manner; a second cam circumferentially varying in radius on an inner circumferential side or outer circumferential side of the cam in a continuous manner; a first operation member operating along a side of the first cam on which the radius of the cam continuously varies; a second operation member operating along a side of the second cam on which the radius of the cam continuously varies; a first piston connected to the first operation member; a second piston connected to the second operation member; a cylinder connecting with the first piston and the second piston and varied in volume by motion of at least one of the first piston and the second piston; and an adjustment unit for rotating at least one of the first cam and the second cam.