Abstract: The invention relates to a hydraulic vane type pump and to a radial piston pump. The cam ring of said pumps is adapted for horizontal and vertical movement. So as to achieve stable operating conditions for the pump at least within a certain range, a single-piece support body is mounted within the vertical adjustment screw so as to avoid a change in the level of height when the cam ring is moved axially.

Abstract: The invention relates to a vane pump having input and output slot means. Either the input slot means or the output slot means are designed such that for a movement of the cam ring into a position of zero excentricity the area of overlap between the input slot means and the output slot means is increased.

Abstract: An adjusting arrangement for a vane or radial piston pump in which the forces applied outwardly to the cam ring are compensated by the application of hydraulic pressure to each of a plurality of sections about the ring. System pressure is applied to one section and a regulating pressure to another. A spring or hydraulic arrangement absorb any force differential.

Abstract: A control valve for a variable displacement pump is improved so that the levelling of the pressure fluctuations of the pump is better and quicker. For this purpose an additional control piston portion on the control piston of the control valve is used. Corresponding to the deflection of the control piston the constriction cross-section set by the control piston portion between the supply connected to the pump pressure line and a passage leading to the control space of the variable pump is varied so that the pressure rise in the control space of the pump and also the pressure drop is accelerated.

Abstract: A hydraulic system comprises an accummulator for supplying hydraulic fluid to a load, a variable displacement pump for charging the accummulator and a valve means for adjusting the pump to deliver a high pressure for charging the accummulator and then to a low pressure when the load is supplied with fluid from the accummulator. By this operation, in which the pump is switched between the zero stroke positions of high and low pressure, the losses of the pump are decreased and the lifetime is increased.

Abstract: A hydraulic pump of the type in which a cam ring and rotor are mounted within a rotor chamber formed between a cover and housing fixedly mounted together. An adjustment screw extends into the rotor chamber transverse to the axis of rotation for adjusting the level of the cam ring. Two pairs of bolts, and only two pairs, extend parallel to the rotation axis at a given radius from that axis to fix together the housing and cover. The distance between the pair of bolts on either side of the adjustment screw and at the pressure region are less than the distance betwen the bolts of the opposite pair at the suction region. Further the angle .beta. between an x-x axis transverse to both the adjustment axis and the rotation axis and the radii of the pair of bolts on either side of the adjustment screw is between 60.degree. and 75.degree. and the angly .gamma. between the x-x axis and the radii of the other pair of bolts is between 25.degree. and 40.degree.

Abstract: A hydrostatic machine having a rotor mounted in a housing and having a leakage oil connection, the leakage oil being conducted before discharge to the tank through predetermined housing portions in order to heat the central part of the housing during the start-up phase of the machine.

Abstract: The pressure response of a pressure control valve is adjusted by a solenoid valve of which the solenoid is connected to an electrical three point control device. A programmed signal and an actual signal derived from a transformer of the control pressure valve are fed to the input of the three point control device.

Abstract: A hydrostatic radial piston pump has a housing with a suction chamber, an eccentric, a pressure valve member spaced from the eccentric and having a convex support, and a movable structural unit arranged between the eccentric and the pressure valve member and including a cylinder with a supporting face and a sealing edge spring-biased against the support of the pressure valve member, and a piston with a piston shoe spring-biased against the eccentric, wherein the supporting face has a circumferential groove subdividing it into an outer and inner annular face portion, the outer annular face portion has at least one substantially radial groove communicating the annular groove with the suction chamber, and the ratio of the force of a biasing spring and the dimension of the supporting face does not exceed substantially 2.5 kp/cm.sup.2.

Abstract: A pressure control valve is provided for controlling both the low and high pressure ranges of a variable displacement pump in addition to the pressure control valve used for adjusting the variable displacement member of the variable displacement pump.

Abstract: A power output control device for a pump having a delivery adjuster, is formed of a housing including a control piston attacked at one end with the output medium of the pump and having means for controlling the pump adjuster; a two-armed rocking lever is supported in the housing for movement parallel to the axis of the control piston, one arm of the lever being biased by a governor spring having a progressive biasing force while the other arm of the lever acts on the control piston against the force of pressure medium; an additional biasing spring thrusts against the other arm of the lever and a first setting screw adjusts the biasing force of the additional biasing means and a second setting screw adjusts the biasing force of the governor spring by adjusting the position of the pivot point of the two-armed rocking lever.

Abstract: A radial piston pump has a housing bounding a suction chamber therein and provided with a plurality of pressure ports spaced from one another in circumferential direction of this housing, and with at least one suction port. A plurality of valve units spaced from one another in the circumferential direction of this housing are provided, each of which includes a pressure valve element located in a respective one of the pressure ports and a sleeve member mounted in the same pressure port radially outwardly of the pressure valve element so as to form, together with the latter, a pressure chamber inwardly of and communicating with the pressure port. A plurality of circumferentially extending channels are formed in this housing and intersect the respective pressure chambers.

Abstract: A radial piston pump comprises a housing bounding a suction chamber therein and at least one valve piston unit mounted in the housing. The valve piston unit includes a pressure valve defining a pressure chamber, a movable piston having an axial passage operatively communicating the suction chamber with the pressure chamber, and a suction valve located in the axial passage of the piston. The suction valve is operative for opening and closing the axial passage of the piston so as to establish and interrupt the above communication, respectively. The piston performs a suction stroke and a working stroke, and a valve member of the suction valve is open during the suction stroke of the piston. The valve member has such a mass that it is opened by an accelerative force produced during the above suction stroke of the piston. The piston is moved by an eccentric mounted on a rotatable shaft, which eccentric has a circumferential groove operatively communicating the suction chamber with the axial passage of the piston.

Abstract: The radial pump preferably for use in connection with a hydraulic clamping device includes a plurality of pumping elements enclosed in a housing and cooperating with a corresponding pluraity of discharge valves. A multiway control valve controls the delivery of pressure fluid to a load port in such a manner that during the actuation of the load the outlet of all discharge valves are united to deliver the entire flow of pressure fluid into the load port, whereas when the load is maintained under a constant pressure, only one pumping element delivers discharged fluid via a single discharge valve into the load port and the remaining pumping elements deliver their output into the reservoir.

Abstract: A radial piston pump has a housing, a shaft mounted for rotation in the housing and including an eccentric provided with a cam track, inlet and outlet ports in the housing, valve means installed in the ports, a plurality of radially reciprocable pistons spaced about the eccentric and each having a radially inner surface in sliding engagement with the cam track, and a layer of synthetic plastic material having a low coefficient of friction on each of the surfaces, so as to reduce friction between the same and the cam track.

Abstract: A hydraulic system has a pump whose outlet is connected to a load and which has a pilot port whose pressurization is proportional to the pressure at the outlet. A restriction is provided between the outlet of the pump and the load. A differential valve is provided connected to the conduit between the pump and the load to both sides of the restriction and serves to compare the difference between pressure upstream and downstream of this restriction with a set point so as to depressurize the pilot port of the pump when this difference exceeds the set point. Furthermore, another valve is provided which compares the pressure in the feed conduit downstream of the restriction through yet another set point and also serves to depressurize the pilot port when this downstream pressure exceeds the second set point.

Abstract: A variable-output pump has an output-adjusting element which is acted upon by a differential piston arrangement having oppositely facing active surfaces of a smaller and of a larger active area. Control fluid is permanently admitted to the smaller active area of the differential piston arrangement to act on the same and urge the output-adjusting element of the pump toward a low-output position. A biasing spring acts against the force of the fluid acting on the smaller surface, and the control fluid is also selectively admitted to the larger surface to urge the adjusting element toward higher outputs. A control slide controls the admission of the control fluid to the larger surface of the differential piston arrangement and has a housing provided with a bore in which a slide is mounted for movement longitudinally of the bore. The slide has an end face acted upon by the control fluid and another end face acted upon by a spring.