Abstract: A pump and motor assembly (20) includes a centrifugal pump (30), a bent axis hydraulic pump 58, and a wet-type drive motor (228). The motor has a rotor and a stator that are submerged in hydraulic fluid for full lubrication and cooling. A drive shaft 66 is driven by the motor. The centrifugal pump has a rotatable impeller (50) for pumping hydraulic fluid from an inlet (48) to the bent axis hydraulic pump. The centrifugal pump also pumps fluid to the motor for lubrication and cooling. The bent axis hydraulic pump pumps the fluid and discharges the fluid from the system. The centrifugal pump and the bent axis hydraulic pump are rotatable along a common rotational axis R1 that is angled relative to the rotational axis R2 of the drive shaft.

Abstract: An axial piston pump has a fluid inlet, a fluid outlet, and a rotatable, one-piece piston housing carrying one or more pistons movable within one or more respective sleeves formed by the housing. A circumferential row of fixed field members is mounted to the housing at a mounting location formed by the housing, the mounting location being radially outward of the sleeve(s). The pump further has a stator surrounding the piston housing and including a circumferential row of armature windings such that the piston housing and the stator form an electro-magnetic motor operable to rotate the piston housing, and a swashplate engaged with the piston(s) such that rotation of the piston housing relative to the swashplate around an axis of rotation produces reciprocating movement of the piston(s) for the pressurisation of fluid received into the sleeve(s) from the fluid inlet and then discharged from the sleeve(s) to the fluid outlet.

Abstract: A pump configured to move fluid from one location to another location is provided. The pump includes a pump housing. The pump housing is composed of a wall structure. The wall structure includes a first laminar portion of a thickness of the wall structure composed of a resin that does not include any reinforcing fibers. The wall structure also includes a second laminar portion of the thickness of the wall structure that is composed a resin with reinforcing fibers dispersed through the resin.

Abstract: The cooling and lubricating system is provided for a piston sealing device for a piston, which includes a fixed skirt and a sliding skirt joined together by an interskirt mechanical connection to axially compress a continuous extensible segment under the action of a sliding skirt spring. The system adds to the device a sliding skirt thrust ring so as to insert between the fixed skirt and the continuous extensible segment a flow valve traversed by the interskirt mechanical connection. The valve is held at rest away from the fixed skirt by a valve return spring on the one hand, and including a flow calibration orifice on the other hand.

Abstract: A piston in a liquid-pressure rotating device in which pistons are arranged at a cylinder block rotatable together with a rotating shaft, includes: a cylindrical peripheral wall main body portion including a hollow portion, an opening portion formed at one end of the body portion and communicating with the hollow portion; a lid portion welded to an inner peripheral surface of the opening portion sealing the hollow portion and including an outer surface formed as a pressure receiving surface which receives liquid pressure; and a stress reducing portion provided on an inner peripheral surface of the body portion, the inner peripheral surface in contact with or close to an end portion of a welded portion formed between the opening portion and the lid portion, the end portion located at the hollow portion side, the stress reducing portion configured to reduce stress acting on the end portion of the welded portion.

Abstract: 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.

Abstract: A piston for an axial machine includes a piston body having a cavity that is closed in a pressure-tight way. The cavity is divided into a plurality of chambers, arranged one beside the other in cross-section.

Abstract: A radial piston machine includes a piston having a base which is provided with a roller. The roller is held secure by a bearing shell that is inserted in the piston base.

Abstract: An example includes an apparatus to pump a fluid. The apparatus includes a housing extending along a length defining an elongate interior, an actuator in the housing, conforming to the elongate interior, the actuator including a plurality of lumens, each having a length extending substantially parallel to the elongate interior, each from around 10 to 200 micrometers across and an actuator configured to oscillate the actuator in the actuator housing along the length of the elongate interior with a rate differential between movement in a first direction versus movement in a second direction opposite the first direction to pump the fluid.

Abstract: A piston for a radial piston machine includes a metal core that is substantially provided with a casing made of plastic. The casing is configured to be produced from PEEK together with a bearing shell as one piece and injection-molded onto the core.

Abstract: A piston unit for a radial piston machine includes a piston and a roller or a roller element. The roller or roller element has a circular cylindrical jacket apart from a chamfer. A hydrostatic pressure- or force-relief element is provided in a contact area between the piston and the roller. The hydrostatic pressure- or force-relief element forms a pressure field in the contact area. The roller or roller element also has one or two end-face holes. Due to the hole(s), the roller is slightly weakened at the associated end section such that Hertzian stress is reduced at the same associated end section.

Abstract: A cylinder includes a cylinder body defining a cylinder bore. End caps close opposite ends of the cylinder body. A piston/rod assembly of the cylinder includes a piston portion and a rod portion. The piston portion is located in the cylinder bore and the rod portion extends outwardly of the cylinder body through at least one of the end caps and terminates at an end having a first interlocking member. The cylinder also includes an attachment member having opposite first and second ends. The first end of the attachment member has a second interlocking member for cooperating with the first interlocking member for attaching the attachment member to the end of the rod portion. The second end of the attachment member includes a mating feature for connecting the attachment member and thus, the rod portion to another part.

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: In a radial piston engine having pistons bearing against the circumference of an eccentric, which pistons execute a swivelling motion upon the rotational motion of the eccentric and are in engagement with a guide body, which bears on the radially outer end by a radially outwardly convex spherical-annular bearing face against a concave spherical-annular bearing face in the housing or cylinder cover. To attain complete piston relief, the bearing arrangement is designed such that the guide body (2) is provided with an upper end face (8) which is acted on by the pressure medium over a hydraulically effective plane (de) extending perpendicularly to the longitudinal axis of the guide body (2). The hydraulically effective plane lies in the area of the bearing face (5) on the housing (6) or intersects the face for all swivelling positions of the piston (3).

Abstract: A propelling apparatus for a vehicle switchable between a four wheel drive mode and a two wheel drive mode. The apparatus comprises a hydraulic pump for driving hydraulic motors associated with front wheels and rear wheels, respectively. A shutoff valve is provided on oil lines extending between the hydraulic pump and one of the hydraulic motors, e.g. the motor associated with the front wheels. The shutoff valve is operable to establish the two wheel drive mode for driving only the rear wheels. A pumping preventive device prevents the hydraulic motor associated with the front wheels from effecting pumping action due to power transmitted from the front wheels when the shutoff valve is operated.

Abstract: A member oscillates on a face and another member pivots on a bed of the first member. Passages are provided through the members to lead a lubrication fluid under pressure into a fluid pocket between the mentioned face and one of the members. The fluid pressure in the pocket carries a major portion of the load of one of the members on the face. The oscillation of the members has one stroke under higher load and one under less load. The pivotal movement of the other member controls the flow of fluid through the passages to provide high pressure in the fluid pocket at the stroke under higher load and lower pressure in the pocket at the stroke under less load. The arrangement is especially suitable to be provided on pistons and piston shoes of radial piston machines. But it can also serve to carry load on other members of machines or vehicles, wherein at least two movements are taking place and a source of supply of fluid under pressure is available.

Abstract: A vehicle with a hydrostatic transmission system of wheel motor type in which the wheel motor is specially designed to meet the strict requirements of the vehicle, with a maximum mechanical efficiency of 0.97, speed ranging from 0 to 1500 r.p.m. for both fixed displacement and continuously variable displacement, and a wide speed ratio. It is compact in size, simple in construction, and easy to produce. The system may include a manual or automatic control device of the continuously variable displacement motor or pump and a distributing valve which can control the individual working mode of each wheel motor, so that the adjustable speed range can be further extended and the mean efficiency of the vehicle can be improved.

Abstract: A system for hydrostatic pressure release of the rocker in the bearing box in an axial piston machine. The pressure-relief system includes slots in the rocker bearing box connected with axial passages through the pistons, pressure pockets in the guide shoes and passageways through the rocker. In order to render the forces in the pressure-relief system essentially constant and speed-independent, the pressure-relief devices of the rocker bearing and four individual slots, two of which are parallel to each other in the region of each of the two bearing surfaces on the rocker and which are connected to the pressure pockets in the guide shoes by the passageways through the rocker.

Abstract: In an axial piston motor or pump the cylinder barrel is mounted on a medial shaft which has a shoulder which axially bears against the front end of the rotor barrel. The rear end of the medial shaft is radially borne in a housing portion. The front portion of the medial shaft is provided with a bearing member of an axial thrust bearing for support on a respective axial thrust bearing member in the housing. On the rear end of the rotary barrel an axially selfthrusting control body is provided to seal the flow of fluid to and from the cylinders of the rotary barrel. The control body presses against the rotary barrel, the rotary barrel presses against the shoulder of the medial shaft and the thrust bearing member of the shaft bears on the thrust bearing member of the housing. As a result thereof the cylinders in the rotary barrel can be straight through bores. The manufacturing of the rotor barrel is thereby simplified and the flow acceleration losses of former bore type cylinders are prevented.

Abstract: A hydraulically operated, swash-plate apparatus such as a hydraulically operated continuously variable transmission includes a cylinder block rotatably supported in a case and having a plurality of axial cylinders arranged in an annular pattern, plungers received respectively in the cylinders, and a swash plate supported in the case and slidably held against the free ends of the plungers through a shoe therebetween. The plungers are movable into and out of the respective cylinders by a stroke determined by the angle of inclination of the swash plate. The shoe having a body and a sliding surface disposed thereon and slidably held against the swash plate and made of a material having a coefficient of thermal expansion different from that of the body of the shoe. The sliding surface becomes convex at a temperature upon operation of the apparatus.

Abstract: An axial piston machine whose pistons are formed as stepped pistons and which bound a first cylinder space and a second cylinder space, wherein the pistons are driven on the driving side via an axially displaceable driving surface on which they slide in a sliding bearing with a pressure pocket which is connected to the first cylinder space by a passage, is arranged so that the loading of the sliding bearings is reduced depending on the operating condition of the axial piston machine. This is achieved by connecting the second cylinder space to a second pressure pocket on one of the two sliding surfaces by a second passage separate from the first passage.

Abstract: A rotary fluid energy translating device which comprises a casing and a couple ring rotatably supported in the casing. Static fluid pressure is applied to the couple ring at circumferentially spaced points and from both the outer and the inner side of the ring so that a couple of forces is produced in the couple ring while providing balanced static pressure on the ring at each of the circumferentially spaced points thereby to rotate the couple ring, which can be connected to a mechanical element outside the casing. By positively rotating the couple ring by means of an external drive, it is possible to operate the device as a fluid pump.

Abstract: This invention relates to a radial piston device with a rotatable casing useful as a pump or a motor. The device is highly efficient with an overall efficiency of 0.95 and a mechanical efficiency of 0.97, a wide rotational speed range of over 1000 rpm, and can be made with continuously variable or fixed displacement. The device is compact in size, light in weight and simple in structure making it easy to manufacture. Moreover, the device can be constructed from a variety of materials without restrictive material requirements, can operate with both filtered and non-filtered oil, and is not sensitive to environmental effects. When the device is mounted on a wheel to form a hydrostatic transmission system, the layout and performance of the vehicle are significantly improved. The displacement control means provided by the present invention is also applicable to other motors or pumps with eccentric shafts. This invention also provides a simple and reliable flat oil seal.

Abstract: The former art provides multi-stroke hydrostatic motors, which perform at a single revolution of the rotor multiple inward and outward strokes of the pistons. A high torque was thereby obtained. The invention discovers, that the know multi-stroke motors have still relatively short piston strokes in relation to the diameter of the rotor.The invention increases the efficiency of multiple stroke motors by the provision of control communications to control the flow of fluid pressure into pockets open to the piston faces and cylinder walls, whereby the torque of the rotor is transferred from the pistons to the cylinder walls by high pressure fluid in the pockets. The invention also provides radial guide extensions to enlarge the stroke of the pistons in a given size and weight of the device combined with the partial movement of the pockets along the guide extensions.

Abstract: In a fluid pump or motor improvements are provided to the piston shoes therein to permit a higher pressure in the respective device. Other improvements are done to the hydrostatic bearings in radial piston or radial chamber type fluid motors and pumps. A further arrangement is, that plural pistons are applied to permit the use of two different fluids in the respective device. This leads also to the application of disc springs and their modification in a pump or motor to make the pumping of non-viscous fluids like water possible at very high pressure. Motors are provided with arrangements to permit them to drive and to carry simultaneously or to have hollow shafts, whereby improved and novel machines and vehicles are obtained.

Abstract: An axial piston pump is disclosed which includes a housing, a cylindrical bore in the housing, a piston barrel rotatable in the bore and spaced from the bore walls and an antifriction bearing structure surrounding the barrel between the barrel and the bore. A plurality of axial piston are provided in the barrel which are open at one end and have fluid passages through the barrel at the other end. A piston is provided in each such piston bore which extends out of the open end. A spring is provided between each piston and the other end of the piston bore. A fixed ramp swash plate is provided in the housing bore beneath the extending pistons and an antifriction thrust bearing is provided between the swash plate and pistons. An axial drive shaft is provided on the barrel which extends through an antifriction bearing in an opening in the housing opposite the bore for drivingly engaging on external drive structure.

Abstract: A rotary fluid energy converter which is used either as a hydraulic pump or as a fluid motor has a housing, a torque ring, pistons, a cylinder barrel, and spaces. The ring is closely held against the inner surface of the housing via first static pressure bearing which are circumferentially spaced from one another. As the ring is rotated relative to the housing, the volumes of the spaces increase or decrease. Each of the first bearings has two pressure pockets axially adjacent each other. Fluid flows out of the spaces and is distributed to the corresponding pressure pockets via restrictors.

Abstract: In a pivot bar portion of a piston shoe in a radial piston device wherein the pivot portion is pivotably borne in a bed in the piston which extends normal to the longitudinal axis of the piston, recesses are provided parallel to the pivot axis whereby bearing lands are formed between the recesses. The bearing lands are tracting fluid out of the recesses along themselves and the bearing bed face of the piston, when the shoes pivot in the piston. A perfectly operational forced lubrication between the pivot portion and the piston is thereby assured which results in a long life and very high bearing capacity between the piston and the piston shoe.

Abstract: The former art provides multi stroke hydrostatic motors, which perform at a single revolution of the rotor multiple inward and outward strokes of the pistons. A high torque was thereby obtained. The invention discovers, that the known multi stroke motors are still too heavy, obtain small overall efficiencies and their power per size and weight is limited because the known motors failed to provide means to carry the tangential loads by fluid pressure power. The invention increases the power and efficiency of multiple stroke motors by the provisions of control means to control the flow of fluid pressure into pockets open to the piston faces and cylinder walls, whereby the torque of the rotor is transferred from the pistons to the cylinder walls by pressure in fluid in the pockets. The invention also provides means to enlarge the stroke of the pistons in a given size and weight of the device.

Abstract: On piston shoes in radial piston pumps, motors and engines the radial load which is excerted by the pressure under the piston onto the piston shoe is to a high rate borne by hydrostatic bearings between the piston shoe and the inner guide face of the piston stroke actuator ring. At high revolutions per given time the centrifugal forces appearing from the masses of piston and shoe increase drastically which results therein, that the bearing capacity of the hydrostatic bearing fails to bear the increased load. The invention gives rules how additional hydrodynamic bearing portions can become provided on the outer portions of the piston shoes, whereby those portions will carry an additional load by hydrodynamic actions. Since the bearing capacity of such bearing portions increases with increase of the rotary speed of the device, the applicable range of revolutions per minute can be increased by the application of the invention.

Abstract: In radial piston pumps and motors the dimensions of the rotor, pistons and piston shoes are optimized for best efficiency and power in a given size and weight. The efficiency and reliability of the piston shoes is improved by the provision of fluid pressure pockets in the outer face of the piston shoe which have cross-sectional areas exceeding the cross-sectional area of the piston whereon the piston shoe is pivotably borne. Welding of the outer face of the piston shoe is prevented and the devices are able to operate with higher pressures and rotary velocities.

Abstract: The former art provides multi stroke hydrostatic motors, which perform at a single revolution of the rotor multiple inward and outward strokes of the pistons. A high torque was thereby obtained. The invention discovers, that the known multi stroke motors are still too heavy, obtain small overall efficiencies and their power per size and weight is limited because the known motors failed to provide means to carry the tangential loads by fluid pressure power. The invention increases the power and efficiency of multiple stroke motors by the provisions of control means to control the flow of fluid pressure into pockets open to the piston faces and cylinder walls, whereby the torque of the rotor is transferred from the pistons to the cylinder walls by pressure in fluid in the pockets.

Abstract: A piston for a hydraulic piston machine in which a piston body receives a ball in a space defined at one end of thereof. A bearing dish supports the ball in the space with an O-ring engaging the recess to seal the bottom surface of the bearing dish. Preferably the bearing dish is formed with a steel support layer, a bronze layer cast onto the steel support layer, and a plastic layer supporting the ball.

Abstract: In a radial piston machine, there is provided an outer stator and an inner rotor rotatable on a control pintle provided with supply and discharge channels. The rotor contains at least one radial bore in which is slidable a spherical piston comprising an outer ball and an inner cylindrical sleeve. The radially inward end of the sleeve, which end is adapted to be acted upon by the outlet pressure of the machine, includes a sealing lip which, during operation, in particular at higher pressures, expands circumferentially and, under certain circumstances, moves in sealing abutment with the inner wall of the radial bore.

Abstract: An axial piston machine of the inclined axis type is operable as a pump or motor has a drive shaft, a drive plate rotatable with the drive shaft, a machine housing, a drum having cylindrical bores inclined to the axis of rotation of the drive plate, pistons reciprocally mounted in the bores and connected to the drive plate, and an axial slide bearing and a radial slide bearing arranged in the housing to provide axial and radial support for the drive plate, in which an improved radial slide bearing comprises a circumferentially spaced arrangement of pressure chambers formed in the outer periphery of the drive plate each corresponding to a respective one of the cylindrical bores, the pressure chamber opening outwardly of the drive plate to form a hydrostatic and a hydrodynamic radial slide bearing with an adjacent internal bearing surface of the housing.

Abstract: A hydraulic radial piston motor with a cam disc and a cylinder block with a number of pistons running in cylinders in the block presses rollers against the cam disc in such a way that a torsional moment arises. The rollers are formed with guide members running in slots in guide units which take up tangential forces. The rollers are mounted in roller cages which are formed with hydrostatic bearings. At their outer end each piston is formed with a part-spherical bearing surface and the roller cage has a cooperating part-spherical bearing surface, which allows angular movements between the roller cages and the pistons in all directions.

Abstract: A filled piston (10) has a tube (19) extending axially through the core (13) of filler material. The tube (19) provides the passage (23) through which hydraulic fluid passes to lubricate the bearing surfaces of components associated with the piston (10). This eliminates the problem of the hydraulic fluid eroding the filler material and thus the need for visual inspection of the passage through the piston.

Abstract: A hydrostatic piston machine has a housing, a rotor, a plurality of pistons rotatable with the rotor, and a displacing element operative for effecting reciprocation of the pistons and having a surface which is in sliding contact with the latter. Means is provided for reducing friction between the surface of the displacing element and the pistons during the sliding contact. This means includes a recess formed in the surface of the displacing element and communicating with a space which is under pressure so that a cushion of pressure fluid develops between the surface and the piston. The space under pressure may be constituted by a low pressure zone of the machine or by the low pressure and a high pressure zone of the machine.

Abstract: A rotating cylinder engine having a stationary housing surrounding a rotating cylinder block which rotates unitarily but eccentrically with an output shaft. The housing rotatably mounting both the shaft and the cylinder block. The output shaft has cam flats cooperatively positioned with cylinders in the cylinder block; the cylinders having sealed outer ends. A piston is slideable in each cylinder with its inner end sealingly and slidingly engaging an associated cam flat. Fluid passages in said cam flats alternate from a source of pressured air and from an exhaust. The pistons have a central bore therein confluent with the fluid passages in the cam flats so that pressure can flow through the piston and react between the outer ends of the cylinders and the cam flats, and the cylinder block and the cam flats rotate unitarily but eccentrically. In one embodiment, bridle rings hold the pistons on the cam flats.

Abstract: A cylindrical piston has a part-cylindrical outcut, which is slotted radially and contains a swingable pivot-member of at least part-cylindrical configuration borne in the outcut and pivoting therein under load. The mentioned outcut is formed partially around an axis which is normal to the longitudinal axis of the mentioned piston and extending through the longitudinal axis of the piston. A plurality of preferably part-annullarily formed grooves for the reception of pressure fluid are provided preferably in said pivot-member in order to lubricate bearing portions of said member between two adjacent grooves or recesses to assure a high pressure lubrication from both ends of the respective bearing portion. Efficiency and lifetime of said bearing portion is thereby increased and so is the bearing capability.

Abstract: A swash plate type hydraulic device comprising a rotary shaft rotatably supported on a frame, a cylinder block mounted on the rotary shaft for rotation therewith, a plurality of cylinder bores formed in the cylinder block in a circular pattern around the axis of rotation thereof, a plurality of plungers slidably fitted in the cylinder bores so as to define hydraulic chambers, a swash plate mounted on the frame in an inclined manner with respect to the rotary shaft in opposing relation to the plungers, an annular shoe being in abutting engagement with the swash plate for relative rotation, a plurality of connecting rods operatively connecting the shoe and plungers, and a pair of synchronous gears respectively mounted on the cylinder block and shoe in meshing engagement with each other for synchronized rotation of the cylinder block and shoe. The connecting rods are universally jointed at one end thereof to the shoe and at the other end thereof to the plungers.

Abstract: A member oscillates on a face and another member pivots on a bed of the first member. Passages are provided through the members to lead a lubrication fluid under pressure into a fluid pocket between the mentioned face and one of the members. The fluid pressure in the pocket carries a major portion of the load of one of the members on the face. The oscillation of the members has one stroke under higher load and one under less load. The pivotal movement of the other member controls the flow of fluid through the passages to provide high pressure in the fluid pocket at the stroke under higher load and lower pressure in the pocket at the stroke under less load. The arrangement is especially suitable to be provided on pistons and piston shoes of fluid handling machines. But it can also serve to carry load on other members of machines or vehicles, wherein at least two movements are taking place and a source of supply of fluid under pressure is available.

Abstract: The present invention relates to an assembly, for use in a pressurized fluid mechanism equipped with pistons bearing against a reaction plate by way of slipper blocks, which assembly consists in such a piston and the associated slipper block coupled to one end of said piston by means of a "ball and socket" type assembly, the male element of the assembly being constituted by that part of the slipper block facing the face supporting the said slipper block on the reaction plate. A bolt comprising a screw and nut, joins the slipper block to the piston, the supporting surfaces of the nut and of the screw head on the corresponding parts of the slipper head and of the piston being of the "ball and socket" type.The invention finds an application in the production of high power hydraulic motors.

Abstract: A cylindrical piston has a part-cylindrical outcut, which is slotted radially and contains a swingable pivot-member of at least part-cylindrical configuration borne in the outcut and pivoting therein under load. The mentioned outcut is formed partially around an axis which is normal to the longitudinal axis of the mentioned piston and extending through the longitudinal axis of the piston. A plurality of preferably part-annullarily formed grooves for the reception of pressure fluid are provided preferably in said pivot-member in order to lubricate bearing portions of said member between two adjacent grooves or recesses to assure a high pressure lubrication from both ends of the respective bearing portion. Efficiency and life time of said bearing portion is thereby increased and so is the bearing capability.

Abstract: A slant plate type hydraulic device is provided which comprises a frame, a cylinder rotatable mounted in the frame and a plurality of plunger means which are slidably fitted into the cylinder. The plunger means are positioned in a circular pattern around the axis of the cylinder. A holder means is provided, along with a slant plate means wherein the holder means holds the slant plate means such that the slant plate means and cylinder are rotatable with respect to one another. Also included is a plurality of shoe means, with each shoe means being universally, rotatably mounted on one of the plunger means, wherein the shoe means are in sliding contact with the slant plate means. Finally, biasing means are provided for holding the shoe means in contact with the plate means.

Abstract: A cylinder block (1) has radial bores (3) of rectangular cross section with a piston comprising a hollow roller (5) and a piston cap (4). The rollers (5) are supported on an outer cam (2). The piston caps (4) are periodically exposed to the pressure (p) of a medium which is delivered to them via channels (11, 13) in side sealing plates (6,7) and via the hollow spaces (10) of the rollers (5). The piston caps (4) are provided with sealing strips (17, 18) resting on bore walls (8, 9) and with support ribs (19, 20). Each roller (5), with the two associated bore walls (8, 9), forms gaps each of which, together with the one sealing strip (17, 18) and bore wall (8, 9) define an intermediate chamber (p.sub.c, p.sub.o). From the intermediate chambers (p.sub.c, p.sub.o) channels (25, 26) lead in the piston cap (4) to the support faces ( 23, 24) of the support ribs (19, 20).

Abstract: In a radial piston pump, motor, transmission the deep diving or entering piston shoe is utilized and swingably borne in the pivot-bed of the radially reciprocating piston.Since deep diving piston shoes have large piston strokes, the shoes pivot in the pistons in large angles.Thereby a considerable force-portion of the load on the piston is transfered to the wall between the piston and the cylinder, whereby heretofore short pistons produced occasionally welding and sticking between the cylinder wall and the piston wall.The piston therefore receives radially extending portions, which may extend beyond the medial portions of the piston show and may even enter into the ring groove of the piston stroke actuator ring. Thereby a very long guidance of the piston on cylinder wall portions is obtained, which makes the application of effective pressure balancing pockets at correct location between piston wall and cylinder wall possible.

Abstract: A glide shoe of a hydraulic piston machine has a glide face which is in gliding contact with a gliding surface of a piston-reciprocating element. The glide shoe has a bore which communicates with an interior of a housing of the machine and extends toward the glide face so that a working medium which flows through the bore causes build-up of a hydrostatic pressure between the bore and the glide surface of the piston-reciprocating element. The glide face is continuous and is interrupted only by recess means which occupies not more than a relatively small portion of the glide face so that a relatively high hydrodynamic pressure can build up between the remainder portion of the glide face and the glide surface of the piston-reciprocating element during working movement of the glide shoe relative to the piston-reciprocating element.

Abstract: A sliding piston joint of a hydrostatic piston machine has a piston having a recess or cavity and a sliding shoe having a head portion receivable into the recess or cavity of the piston so as to support the latter. The sliding shoe has a base portion having a surface which faces away from the piston and faces toward a hydrostatic pressure zone generated during operation of the machine. The head portion of the sliding shoe and the piston have surfaces which are in sliding contact with one another. A throughgoing passage extends through the sliding shoe so that a portion of working fluid flows from the hydrodynamic pressure zone to the contacting surfaces of the sliding shoe and the piston to thereby relieve the latter.

Abstract: A fluid pressure machine such as a motor or pump has an orbiting cylinder block (9) housing a number of radial pistons (11) sliding within respective cylinders (10). Each piston has a cylindrical coaxial bore in which a fluid displacing member (13) fixed to the cylinder block is located so as to define within the cylinder an annular outer chamber (14) and an inner chamber (15). A selectively operable spool valve (36) is arranged for supplying hydraulic fluid under pressure to the inner and/or the outer chamber and thereby control the operating speed of the machine.