A hydraulic piston unit including a rotational group for driving or being driven by a driving shaft, and having a tiltable displacement element for adjusting the displacement volume of the rotational group between a minimum or a maximum displacement, wherein, on t valve segment between a kidney-shaped inlet port and a kidney-shaped outlet port at respective dead end positions of reciprocally moveable working pistons first and second control ports are located in fluid connection with cylinder bores in the cylinder block, for controlling the position of the displacement element. The hydraulic piston unit further includes a control valve with a shiftable control valve spool fluidly connected via a high pressure port to a high pressure side of the hydraulic piston unit. The control valve spool is configured to conduct hydraulic fluid from the high pressure side to one of the first or the second control port.

A swash plate type liquid-pressure rotating device includes a movement restricting mechanism configured to restrict a movement of a spherical bushing relative to a rotating shaft toward a first side in an axial direction. The movement restricting mechanism is a restricting member such that a portion of the spherical bushing which portion is located at the first side in the axial direction contacts the restricting member. The swash plate type liquid-pressure rotating device further includes: a stopper attached to the rotating shaft; and a gap adjusting member. The gap adjusting member is inserted into a gap G3 formed between the stopper and the bearing when the spherical bushing, the retainer plate, the shoe, and the swash plate tightly contact one another in the axial direction. The gap adjusting member restricts a movement of the rotating shaft relative to the casing toward the first side in the axial direction.

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.

A hydrostatic axial piston machine has a housing. In the housing of the hydrostatic axial piston machine, an actuating pressure cylinder is formed at an angle to the drive shaft. A control valve is inserted into the actuating pressure cylinder in a cartridge type of design. In order to enable maximum movement of an actuating piston in the direction toward the control valve, the cartridge is of shortened design. To this end, an actuating pressure port, which is arranged between a high-pressure port and a low-pressure port, and an actuating pressure passage are arranged completely inside the cartridge.

A control mechanism for a hydrostatic transmission includes a piston rod, a neutral biasing spring, a piston, a cylinder case provided with a first fluid chamber and a second fluid chamber, a solenoid valve capable of selectively supplying pressurized fluid to the first fluid chamber and the second fluid chamber, a pivot shaft configured to swingably support the cylinder case, and a first relief valve configured to flow the hydraulic fluid from the first fluid chamber to the second fluid chamber when a hydraulic pressure in the first fluid chamber exceeds a set pressure, and a second relief valve configured to flow the hydraulic fluid from the second fluid chamber to the first fluid chamber when a hydraulic pressure in the second fluid chamber exceeds a set pressure.

A fuel pump system for an aerial refueling system including: a variable displacement motor operable to be driven by a hydraulic fluid pressure; a fuel pump operable to be driven by the variable displacement motor; and a drive system controller (DSC) connected to the variable displacement motor, wherein the DSC is operable to direct an operation of the fuel pump in modes comprising: a flow control mode operable to maintain an output fuel flow rate from the fuel pump to a predetermined maximum inlet pressure at a reception coupling for a receiver aircraft; a fuel pressure control mode operable to regulate the output fuel flow rate to not exceed the predetermined maximum inlet pressure; and a priority mode operable to reduce the output fuel flow rate in response to a decrease in the hydraulic pressure. Also a method of refueling a receiver aircraft.

An axial piston machine includes a housing, an actuating piston, and a closing screw. The housing includes a cylinder bore, a recess, and a fluid channel. An end of the bore open to an outside of the housing has an internal thread. The recess is located in a region of the internal thread, and is deeper than a thread depth of the internal thread so that a floor region of the recess is free from thread turns. The piston is linearly moveable in the cylinder bore, and is configured to adjust a displacement volume of the machine. The screw is screwed into the internal thread so as to form a closed chamber between the piston and the screw. The fluid channel opens into the floor region of the recess, and is fluidically connected to the cylinder chamber.

An articulated coupling is provided for a piston sealing device for a piston which includes a fixed skirt and a sliding skirt interconnected by a mechanical inter-skirt connection for axially compressing a continuous extensible segment under the action of a sliding skirt spring, the coupling replacing, on the one hand, the fixed skirt by a ball-joint skirt and providing, on the other hand, a troncospherical piston end which cooperates with a skirt troncospherical bearing surface provided on the ball joint skirt while an articulation unit interposed between the inter-skirt mechanical connection and the piston and/or between the connection and the sliding skirt.

The present disclosure relates to a sealing assembly for a hydraulic piston pump/motor. The sealing assembly comprises a cylinder block, a fluid distribution member, and a sealing member disposed between the cylinder block and the fluid distribution member. The sealing member encloses and seals a fluidic connection between the cylinder block and the fluid distribution member. The present disclosure further relates to a hydraulic piston pump/motor comprising said sealing assembly.

A swashplate-type axial piston machine includes a housing, a first pivot bearing received in the housing, a drive shaft rotatably mounted in respect of an axis of rotation, a cylinder drum, a control plate, a third control aperture in the plate, and a first channel arranged in the housing. The first pivot bearing delimits a first and second housing space from one another. The drum and the plate are arranged in the first housing space. The plate has at least a first and at least a second control aperture. The first aperture is in fluidic exchange connection with a first fluid connection on the housing. The second aperture is in fluidic exchange connection with a second fluid connection on the housing. The third aperture is arranged in the peripheral direction between a first and a second aperture. The first channel fluidically connects the third aperture to the second housing space.