Manual displacement control device (MDC) for hydraulic units has an input shaft mounted rotatably about an input shaft axis in an input shaft block. The input shaft protrudes from the input shaft block with a first end, onto which a rotating torque can be applied. The MDC further includes a control spool housed in a control housing, which is moveable by means of rotating the input shaft for controlling a servo pressure. The control device has positioning means for adjusting and fixing the lateral position of the input shaft with respect to the control housing in a direction perpendicular to the input shaft axis and perpendicular to the direction of a restoring force exerted on the input shaft. The hydraulic unit is adjustable to its neutral position by means of a servo spring bracket providing an end stop surface for a servo spring seat towards the displacement element. The servo spring bracket is variably fixable to the hydraulic unit housing in a manner so that the orientation of the end stop surface can be adjusted parallel to the neutral position of the displacement element.

A hydraulic system according to the present invention includes a rotational shaft, a hydraulic rotor supported by the rotational shaft so as to be incapable of relative rotation, an output adjuster varying a volume of the hydraulic rotor, a control shaft tilting the output adjuster, a drive motor operating the control shaft around the axis, a drive shaft disposed on a reference axis same as the axis of the control shaft and operably driven around the axis by the drive motor, a deceleration mechanism decelerating rotary power input from the drive shaft and outputs the decelerated rotary power toward the control shaft, and a housing accommodating the hydraulic rotor, the output adjuster, and the deceleration mechanism, wherein the deceleration mechanism has a hypocycloid-type deceleration mechanism disposed on the reference axis.

A pump, including: a cylinder block including two through-bores and two pistons disposed in the through-bores; a drive shaft to rotate the cylinder block; a swash plate to displace the pistons within the through-bores to draw fluid through an inlet port into the through-bores; and expel the fluid from the through-bores into the outlet port; a torque sensor arranged to measure torque on the drive shaft and transmit a torque signal, including the measured torque, to a processor; and an actuator to receive, from the processor, a control signal generated using the torque signal and pivot the swash plate about a first axis, transverse to the axis of rotation, or maintain a circumferential position of the swash plate about the first axis; or pivot the cylinder block about a second axis, transverse to the axis of rotation, or maintain a circumferential position of the cylinder block about the second axis.

A variable displacement swash plate type piston pump includes first and second housing members fastened to each other by fastening members, a rotary shaft, a swash plate. A section of the inner circumferential surface of the first housing member has a recess. A bulging portion is arranged in a section of the outer circumferential wall of the first housing member. A section of the outer circumferential wall of the second housing member has a closing portion that closes the opening of the recess. The fastening members include first and second fastening members arranged at positions that are on the opposite sides of the recess, inside the width of the swash plate in a direction along the inclination axis of the swash plate, and closer to the rotary shaft than the distal ends of the bulging portion and the closing portion in the bulging direction.

In a drive device using a hydraulic pump controlled by a rotatable swash plate, the swash plate includes a pocket and a trunnion engaged to the pocket and rotatable about an axis of rotation offset from the swash plate axis of rotation. An interface is formed on a first end of the trunnion, and a first arcuate side of the interface engages a flat portion of the first side of the pocket as the trunnion is rotated in a first direction, and a second arcuate side of the interface engages a flat portion of the second side of the pocket as the trunnion is rotated in the opposite direction. The swash plate may also include at least one protrusion on a top surface extending in a direction perpendicular to swash plate axis of rotation to engage the housing and limit axial movement of the swash plate.

Provided is a variable displacement pump which includes a cylinder block including a plurality of cylinder bores formed in a rotation shaft in a circumferential direction and rotating together with the rotation shaft, a piston provided inside each of the plurality of cylinder bores to be slidable, and a swash plate supported to be tiltable with respect to the rotation shaft while a distal end portion of the piston is slidable thereon and which sucks and discharges a working fluid by moving the piston in a reciprocating manner with a stroke in accordance with an inclination angle of the swash plate, the variable displacement pump including: a control piston which includes a piston portion pressing the swash plate and controls the inclination angle of the swash plate; a piston accommodation portion which is formed in the housing and accommodates the piston portion; and a hollow cylindrical guide portion which is disposed between the piston accommodation portion and the piston portion and includes an inner peripheral surface supporting the piston portion to be slidable thereon, in which the housing is formed of a material having higher fatigue strength than the guide portion and the guide portion is formed of a material harder than the housing.

The invention relates to a device (10) for controlling the displacement of a machine (20) with axial pistons comprising a case (23) that houses a control unit comprising a displacement control spool (110) adapted to be switched between two positions by a control pressure (Ps) according to an axis of sliding (): a working position wherein the control spool (110) provides a connection between at least one inlet (103, 104) that receives a supply pressure and an outlet (105, 106) connected to a cylinder for adjusting the inclination of said machine (31a, 31b), and an idle position wherein the control spool (110) interrupts the connection between said inlet (102, 104) and said outlet (101, 103), and comprising means for switching adapted to vary the position of the adjusting cylinder (31a, 31b), a spring (140), characterised in that: said means of communication comprise a second switching spool (130), coaxial to the control spool (110), a switching pressure (Pm) exerts an axial force on the second spool (130) in the direction of the control spool (110), the spring (140) exerts an axial force on the two spools (110, 130), which tends to move them apart from each other, control pressure (Ps) exerts an axial force on the control spool (110) in the direction of the second tool (130).

A hydrostatic axial piston machine includes a housing, a cylinder barrel, and a drive shaft, which are connected together and mounted in the housing so as to rotate jointly about a first axis. The machine also includes a swash plate mounted in the housing so as to pivot about a second axis to adjust a swept volume of the machine. The machine further includes a hydraulic actuating apparatus, which has an actuating piston that delimits an actuating chamber. The machine also includes a regulating valve attached to a flange face of the housing. The regulating valve has connections situated in the flange face that are used to communicate hydraulic fluid to and from the actuating chamber. The flange face is arranged obliquely so as to enclose an angle with the second axis that is greater than 0 and smaller than 90.

A hydraulic machine comprising: an outer casing comprising a first front plate and a second front plate, a shaft rotatable about a main axis, a first rotor comprising a first rotor body rotatable with said shaft around said main axis, and a plurality of first pistons with respective spherical ring heads fixed to said first rotor body, a second rotor comprising a second rotor body and a plurality of second pistons with respective spherical ring heads, wherein the second rotor is rotatable about a secondary axis, inclined with respect to said main axis, a plurality of sleeves that are separate and independent from each other, each having a cylinder open at opposite ends and engaged on opposite sides by a first piston and by a second piston.

The present disclosure relates to a piston assembly, the piston assembly comprising a cylinder extending along an axis and having an open axial end, a cap assembly closing the cylinder at its open axial end, wherein the cap assembly comprises an insertion portion received in the cylinder at its open axial end, and a piston axially movably disposed within the cylinder and partially received in the insertion portion of the cap assembly. The present disclosure further relates to a variable displacement hydraulic unit including said piston assembly.