Abstract: A hydrostatic machine comprising a stator and a rotor. The stator comprises an inner cylindrical surface with a constant diameter and a cam ring comprising a cam track on the inner circumference thereof, the outer circumference of the cam ring being mounted in the aforementioned inner cylindrical surface. The hydrostatic machine also comprises two bearings that allow the rotation of the rotor in relation to the stator and that are mounted on the inner cylindrical surface of the stator, axially on either side of the cam ring, the cam ring and the two bearings having the same outer diameter.

Abstract: A hydrostatic axial piston machine includes a housing, a connection plate closing the housing, working connections formed on the connection plate, a drive shaft, a swashplate, a cylinder drum coupled to the shaft in the direction of rotation, bores formed in the drum and each including a piston, a control plate against which the drum bears, a retraction plate for removing a piston from the bores, and a retraction ball arranged in front of the first end face of the drum which surrounds a drum neck of the drum and the shaft and by which the retraction plate is loaded in the direction of the swashplate. A pressure chamber is defined by seals between the retraction ball, the drum, and the shaft, and is configured to be acted upon by a pressure above a housing pressure. The retraction ball is sealed against the drum neck and against the shaft.

Abstract: A bent-axis hydraulic pump motor includes: a cylinder block, a retainer plate; and a constant velocity joint, which includes an inner joint element; an outer joint element; and a plurality of balls interposed between block-side ball grooves and shaft-side ball grooves to transmit torque between the cylinder block and the retainer plate, so that all block-side groove planes, which include respective extending axial lines of the block-side ball grooves and the inclined rotation center, are inclined with respect to an axial center of a center shaft and all drive shaft-side groove planes, which include respective extending axial lines of the shaft-side ball grooves and the inclined rotation center, are inclined with respect to an axial center of a drive shaft such that loads applied to a cage in an axial direction from the balls are balanced.

Abstract: Methods and apparatus are provided for lubricating a piston-to-shoe interface in a hydraulic motor or pump. Piston assemblies are installed in a housing that are each adapted to receive a reciprocating drive force and are each configured, in response thereto, to cyclically move between an intake direction and a discharge direction. Each piston assembly includes a piston and a piston shoe, and the piston, the piston shoe, or both have a plurality of pockets formed in a surface that defines a piston-to-shoe interface. When the pistons cyclically move, liquid is supplied to each piston-to-shoe interface to form a hydrostatic bearing at each piston-to-shoe interface. A portion of the liquid that is supplied to each piston-to-shoe interface is selectively supplied to and from one or more of the plurality of pockets.

Abstract: A hydraulic machine arrangement includes at least one hydraulic machine having a plurality of pistons reciprocating within corresponding cylinders. The pistons can be driven by a cam to operate the hydraulic machine as a pump, and they can drive the cam to operate the hydraulic machine as a motor. The hydraulic machine can be configured to selectively disengage a certain piston or pistons from the cam to operate at less than full displacement. Controlling the pressure in the cylinders corresponding to the disengaged pistons can be accomplished by a number of mechanisms, including selectively exhausting fluid from the cylinders, or using a jet pump to siphon off some of the fluid from a high pressure side of the hydraulic machine. Two of the hydraulic machines can be mounted together to help balance axial forces and eliminate the need for an expensive high capacity thrust bearing.

Abstract: According to the present invention, a reciprocating compressor with a rotary valve comprises a cylinder block with plural cylinder bore, a drive shaft which is supported and permitted to rotate in relation to the cylinder block, a piston which is housed in the cylinder bore and allowed to reciprocate therein, a power transmitting unit which connects the piston and drive shaft, a rear housing wherein an intake chamber and exhaust chamber are formed, and a rotary valve which rotates with the drive shaft and is installed in the inner surface of a coupling hole formed in the cylinder block and permitted to slide and rotate therein. In the inner circumference of the cylinder block, connection holes are respectively connected to the cylinder bore. A bypass unit is included between the coupling hole and rotary valve and bypasses the refrigerant remaining in the connection hole of one cylinder bore during the compressive stroke of the piston, then discharges it through the connection hole of another cylinder bore.

Abstract: A hydraulic control circuit for a radial piston engine with two speeds. The changeover between the speeds takes place through the alteration of the absorption volume, the delivery side being connected to the discharge side with a bypass connection by a valve arrangement for a selected number of engine pistons. The control circuit provides a space-saving way of ensuring that the changeover between speeds occurs smoothly and in such a manner to preserve the individual components as far as possible. To this end, at least one intermediate switching position, in which the delivery side is throttled to the discharge side, i.e. connected by a diaphragm-type arrangement, is provided in front of valve arrangement between the two end switching positions. The valve arrangement is preferably driven such that a valve body can be moved through the intermediate switching position at a controlled speed.

Abstract: A hydrostatic transmission including a hydraulic pump and a hydraulic motor fluidly connected with each other, being immersed in an oil sump formed in a housing. A pair of oil passages for fluidly connecting the hydraulic pump with the hydraulic motor are formed in a center section on which the hydraulic pump and the hydraulic motor are mounted. The center section is provided on an outer surface thereof with a pair of openings of the respective oil passages. A control arm is disposed in the housing so as to interlock with a pump capacity changing member like a movable swash plate, thereby enabling the pump capacity changing member to be moved to various actuation positions including a neutral position in association with rotation of the control arm rotated to various actuation positions including a neutral position. A contact member having a surface abutting against the pair of openings of the center section is formed integrally with the control arm. A pair of oil passages are provided in the contact member.

Abstract: A hydraulic motor arrangement including a hydraulic motor having an inlet port arranged to receive a driving fluid, and an outlet port whereby fluid can exhaust from the motor, the arrangement incorporating a by-pass line interconnecting the inlet and the outlet ports, a non-return valve being located within the by-pass line and being arranged to permit fluid flow from the outlet port to the inlet port but to substantially prevent fluid flow in the reverse direction.

Abstract: A hydrostatic transmission is provided comprising a hydraulic pump and a hydraulic motor fluidly connected with each other through a closed fluid circuit. Pistons press against a control arm connected with a movable swash plate of the hydraulic pump and generate a friction force when the movable swash plate, which has been rotated slantwise, automatically returns toward the neutral position by a neutral return spring. The movable swash plate gradually returns to the neutral position by pressure of the piston. A discharging oil hole is open at the utmost end of each of the pistons for draining a portion of operating oil which operates the piston in the closed fluid circuit to the interior of a housing. Grooves are formed along a surface of the control arm abutting against the pistons.

Abstract: An axial plunger slurry pump comprises a pump body, a sloping cam plate, a swashplate, cylinders, plungers and a pump head. Each of the plungers comprises a plunger body with a rubber piston positioned in its front end and being able to slide over it, and an oil receiving gap communicating with an oil passage disposed between two facing end surfaces of the plunger body and the rubber piston. There are check valves each of which is provided in an oil passage between a ball of each of two-ball links, which ball is coupled with the swashplate, and the swashplate. Each of the cylinder and the plunger body are fitted together by means of a half-and-half locating pad, a cylinder sleeve, a pressing cap, and a locking device. The pump may be used widely in drilling, electric power, mine, building, and metallurgy, etc., for conveying mud, mortar, ore pulp, coal pulp, concrete, etc.

Abstract: This invention relates to a device to reduce pulsations on a hydrostatic positive displacement unit, such as an axial piston machine or a radial piston machine which can be used both as a pump and as a motor. The direction of rotation of the positive displacement unit is reversible and at least one piston is mounted so that it can move longitudinally in a cylinder bore forming a cylinder chamber. The device has a buffer element which can be brought into communication with the cylinder chamber by a connecting channel.

Abstract: A hydrostatic transmission is provided comprising a hydraulic pump and a hydraulic motor fluidly connected with each other through a closed fluid circuit. Pistons press against a control arm connected with a movable swash plate of the hydraulic pump and generate a friction force when the movable swash plate, which has been rotated slantwise, automatically returns toward the neutral position by a neutral return spring. The movable swash plate gradually returns to the neutral position by pressure of the piston. A discharging oil hole is open at the utmost end of each of the pistons for draining a portion of operating oil which operates the piston in the closed fluid circuit to the interior of a housing. Grooves are formed along a surface of the control arm abutting against the pistons.

Abstract: This invention relates to a device to reduce pulsations on a hydrostatic positive displacement units, such as an axial or radial piston machine working both as a pump and as a motor with a reversible direction of rotation. In the displacement units, at least one piston is mounted so that it can move longitudinally in a cylinder bore which forms a cylinder chamber. The device has a buffer element which is in communication with the high-pressure side and can be brought into connection with the cylinder chamber. The device reduces pulsations on hydrostatic positive displacement units by which the reversing actions of the cylinder chambers are optimized and the pulsations are effectively minimized in a broad bandwidth of operating conditions. A switchable valve, in particular a non-return valve which opens toward the cylinder chamber is located in a connecting channel between the buffer element and the cylinder chamber.

Abstract: A hydraulic pump or motor having a rotary cylinder barrel formed with a plurality of cylinders in which a corresponding number of plungers are axially slidably disposed for reciprocation and a valve plate in frictional engagement with an end face of the cylinder barrel and being formed with a suction slot and a discharge slot to be communicated with the cylinders of the barrel, wherein the cylinder barrel is contained within a cavity formed in a housing having an end wall formed with an inlet passage in open communication with the suction slot of the valve plate and an outlet passage in open communication with the discharge slot of the valve plate, and a fluid control valve assembly is disposed in the end wall of the housing to permit the flow of hydraulic fluid supplied therethrough into the cavity of the housing from the outlet passage when applied with the pressure of hydraulic fluid higher than a predetermined value.

Abstract: A hydraulic continuously variable speed transmission includes a hydraulic pump and a hydraulic motor, at least one of said hydraulic pump and motor being of variable displacement type. A hydraulic path is formed in a member of the pump which rotates in synchronism with an output shaft of engine, for communicating hydraulic a pressure chamber of the hydraulic pump with a drain. A check valve is provided in the hydraulic path for closing the hydraulic path under centrifugal force created by the rotation of the member when this member is in rotation faster than a predetermined speed, and for opening the hydraulic path against a centrifugal force when the member is in rotation slower than the predetermined speed.

Abstract: A hydraulic pump/motor in which working piston elements are arranged for radial reciprocation. A cam is arranged eccentrically to a rotor which carries the pistons. Fluid cavities are provided in feet on the pistons, in the faces of a polygon to which the feet are attacahed, and in bearing pads in the outer ends of the cylinders to provide hydrostatic balancing. The pistons are hollow and are equipped with check valves to prevent centrifugal force from expelling fluid from the polygon and foot cavities. The cam includes mating spherical surfaces which compensate for bending forces applied to the cam. An improved mechanism for adjusting the cam position uses inherent forces to eliminate the need for a power assist device for cam adjustment. Port plates on opposite sides of the rotor provide inlet to the unit near the axis of the unit and outlet near the outer edge to alleviate stresses and increase efficiency.

Abstract: A radial-piston machine has a rotor formed with a plurality of each a piston carrying radial cylinders.Each such piston is formed on its radially outer end with a part-spherical seat and a part-spherical portion of a respective piston shoe that rides on an eccentric cam in the housing is engageable in each seat. Each such piston shoe may move radially into and out of engagement with the respective piston. A pair of end members axially flank the piston shoes to prevent their escape in axial-direction.The piston-engaging portions of the shoes are always engaged radially in said cylinders. The cylinders may have outer portions with a cross-slot extending parallel to the axis of the rotor through said cylinders. The pistons and shoes may embrace each other partially or be radially free of each other, so, that either the connected piston and piston shoe assembly moves radially between end elements associated to the rotor or the pistons and shoes move unconnected to each other radially between said end elements.

Abstract: The axial piston machine, such as an engine or a pump, comprises a radial hydrostatic bearing for the drive shaft in the form of an oil gap between a conical shaft portion and a corresponding conical boring in a bearing block. The gap has a plurality of bearing pockets normally supplied with high-pressure oil via throttling means communicating with the high-pressure oil. An auxiliary axial hydrostatic bearing in the form of a bearing gap defined between the face of the bearing block near the tapering end of the bearing body and a radial extension of the drive shaft is supplied with an auxiliary low-pressure oil having an approximately constant pressure. A self-adjustable pressure chamber is provided in a plane parallel to the axial hydrostatic bearing gap and is defined by a collar supported on the drive shaft opposite the first radial extension and communicating with the axial bearing gap via a conduit.

Abstract: An axial piston machine of the swash plate type includes a valve plate provided in a front face thereof with control openings which communicate at opposite ends through bores with the rear face of the valve plate. A plurality of shallow pockets, respectively forming hydrostatic bearings, are also provided in said front face, which communicate through connecting bores respectively with throttle bores, which in turn communicate at inner ends with respective control openings, and in which spring loaded throttle pins are arranged with small clearance for oscillating movement.

Abstract: Radial piston pump or motor has within its housing a stationary pintle valve, an external shaft connected to a rotating spider of which are mounted pressure balanced pivotal cylinders. Rigid piston - shoe assemblies engage the cylinders and ride on a cylindrical raceway the eccentricity of which is adjustable for stroke. Balanced annular sealing is provided between the pivotal cylinders and arcuately surfaced pockets therefor in the rotating spider/rotor.