Abstract: A hydraulically unblockable non-return valve has a control piston (21), the control side of which can be connected with a control pressure medium source (35) and the other side of which can be connected with a supply container (33). In order to create a hydraulically unblockable non-return valve, in which the control side of the control piston does not need to be relieved of pressure, the other side of the control piston is perpetually connected with the supply container. Also provided is a throttle bore (27) which connects the two sides of the control piston with each other.

Abstract: A device for controlling a consumer, in particular a hydromotor includes a restrictor, preferably an electrohydraulic proportional directional control valve, and a control valve operating on the basis of a releasable non-return valve. The control valve is provided with an actuating cylinder-and-piston unit having control ports and a biasing spring for the piston. The control valve also has a connecting port which is connected with a connecting port of the restrictor. In order to substantially simplify the structural design of the device, a flow regulator is installed between the control port of the control valve and the connecting port of the restrictor which is connected with the consumer. The control sides of the flow regulator and the control valve are connected through a throttle with a supply container. The space of the cylinder-and-piston unit adjoining the control side of the control piston is connected with another connecting port of the control valve and with the restrictor.

Abstract: A hydrostatic machine having a fixed displacement volume which is connected to the operating chamber of a hydraulic cylinder which machine is mechanically coupled to a second hydrostatic machine having a variable displacement volume to control the force exerted by the hydraulic cylinder. When control liquid is displaced from the working chamber of the cylinder the first machine acting as a motor drives the second machine which displaces control liquid into an accumulator. Vice versa, liquid is taken from the accumulator and the second machine acting as a motor drives the first machine which feeds liquid into the working chamber. The pressure in the working chamber, or, respectively, the force exerted by the cylinder is maintained constant by a corresponding adjustment of the displacement volume of the second machine.

Abstract: A pressure-reducing valve is secured to a proportional magnet by resiliently connecting the valve sleeve of the valve receiving the piston to the housing of the proportional magnet, thus avoiding possible deformations of the valve sleeve resulting from mounting. Furthermore, the operational safety of the valve is improved by abutments limiting the stroke of the valve piston and by a control edge which is additionally provided at the valve sleeve.

Abstract: The invention relates to pressure relief valves which spring bias is controlled by a proportional magnet. The force applied by the proportional magnet is increased by an additional hydraulic pressure force which acts on the spring. There is the advantage of decreasing the size of the proportional magnet and/or increasing the flow capacity of the valve.

Abstract: A first front face of a main control spool of a main control valve is loaded with a constant pressure, whereas the opposite face is loaded with a controlled pressure to control the fluid passages to and from a hydraulic actuator. The control pressure is adjusted by means of a two-edge control of the pilot control spool of a pilot control valve which is actuated by a single proportional solenoid against the force of a spring. The advantages obtained thereby result in a substantial savings in manufacturing expenditure and a substantially improved control operation.

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: An arrangement for controlling a hydraulic motor having supply and discharge sides, has a throttling directional valve having supply and discharge sides and a port, a speed lowering brake valve controlling the discharge side of the hydraulic motor and having a control piston with a control side and a port connected with said port of said directional valve, a control valve arrangement between the control side of the control piston and the supply side of the hydraulic motor and having end sides with end side ports, the control valve having a control slider which selectively connects the control side of the control piston with the supply side of the hydraulic motor and disconnects the control side of the control piston from the latter, is constantly connected at the end side ports with the discharge side of the hydraulic motor prior or after the directional valve and connects the discharge side of the hydraulic motor after the directional valve with the control side of the control piston or disconnect the discha

Abstract: A radial piston machine has a cylindrical housing which encloses a rotary shaft formed with an eccentric. A plurality of stationary piston rods is connected to the inner wall of the housing and radially directed toward the shaft. The free ends of piston rods are provided with ball-and-socket joints permitting universal rotary movement of the pistons. Each piston slidably engages the inner wall of an assigned cylinder which at its bottom wall slidably engages the eccentric. In a modification, the spherical surface of the stationary ball joint directly engages the inner wall of the cylinder.

Abstract: A pressure fluid operated limit switch, particularly for a device for controlling an adjusting element in dependence upon a control value and a reference value. The limit switch includes a housing formed with a recess in which a spring-biased valve member is positioned. The valve member normally abuts against a valve seat formed by a shoulder in the switch housing is at times moved away from that seat against the force of the spring in response to a condition of the adjusting element with which the limit switch is mechanically connected. In order to ensure rapid movement of the valve member away from its seat and thus preventing throttling of the pressure fluid when the switch is in its open position the valve member is provided with the actuating element rigidly connected thereto and carrying at its free end an axially slidable sleeve biased by a spring which is clamped between that sleeve and the valve member.

Abstract: The assembly is used with a support having a flat surface and formed with a bore extending generally parallel to but beneath the surface and with a passage extending from the bore to the surface, with a control element in the bore and pivotal therein about an axis generally parallel to the surface, and with a control rod projecting from the element through the passage beyond the surface. This rod is connected to the element and pivots therewith about the axis through an arc on pivoting of the element in the bore about the axis. The assembly comprises an elastomeric annular cuff having an inner periphery tightly engaging and secured against movement on the rod and an outer periphery engaging and slidable on the surface all around the passage and dimensioned to engage the surface all around the passage in any position of the rod. This cuff is prestressed generally parallel to the rod between its peripheries to press at the outer periphery against the surface.

Abstract: A slide valve, in particular the piston of a switching valve, is actuated in both directions of adjustment by a pressure medium which acts on the annular face and/or the circular face of a regulating piston fixed one-sidedly to the slide valve. The equalization of the differing controlling forces, determined by the different sized surfaces of the regulating piston that are subjected to pressure, is achieved by means of a spring or by an hydraulic counterforce.

Abstract: A control-circuit throttle valve assembly coupled to and regulating a hoisting unit correcting element or final control element of a tractor via a mechanical coupling including a throttle housing, a flow restrictor throttling body shiftably mounted in the throttle housing, the throttling body having a guiding edge portion, a control conduit with a circular cross-section communicating with the throttle housing, the control conduit including a pass-through area, and a run-off conduit communicating with the throttle housing, the guiding edge portion at least partially closing off communication between the control circuit and the throttle housing through the pass-through area upon shifting of the throttling body within the throttle housing such that the pass-through area is throttled as a linear function during operation of the hoisting unit.

Abstract: A suction container for two hydraulic circuits, particularly for a steering circuit and a control circuit has a housing lower portion closed with a cover. A suction tube is inserted into the housing lower portion, which tube is connected to a first consumer line. The container also includes connections which are in communication with a second consumer line and with a fluid supply container. During operation the suction container is under predetermined pressure. A filter device is disposed in the cover before the connection to the second consumer line. A pressure-limiting valve and a reverse valve openable into the container housing are also mounted in the cover.

Abstract: Electromagnet solenoid with a housing in which a winding support supporting the magnet winding is arranged, having an armature which supports at least one stem and is mounted to be capable of moving to and fro within the winding support, and with end pieces terminating the housing. For guiding the armature a sleeve made of magnetic material is provided within the winding support, and said sleeve has on its surface directed towards the armature a sliding coating defining an air gap (i.e. a space free of magnetic material,) and in addition to serving for guiding the armature the said sleeve serves for redirecting magnetic flux.

Abstract: A device for the positioning of an adjustment element dependent upon a desired level and the actual level, particularly for the adjustment of a hoist gear train of a tractor, a combine or the like, has an operating circuit 10, which has a multi-way valve 3 pressure-operated in two directions, and a control circuit 29 for the operation of the multi-way valve, connected to a pressure source 19, which is connected to two control devices 11, 12 of the multi-way valve. Circuit 29 has two adjustable series-connected throttles 22, 24, connected to one of the two control devices. The first throttle 24 is also connected to a tank 7 and the second throttle 22 is also connected to pressure source 19. Both throttles have the same maximum flow-through cross section, and are adjustable in the same manner. Third and fourth throttles 27, 28 are provided, one being between the pressure source and control device 11, and the other between the control device and tank 7.

Abstract: A device for controlling the connection between a pressure medium source and a medium supply container is provided in a pressure medium operated system. The device includes a control valve with a housing formed with a longitudinal bore, in which a valve member is axially displaced between two end positions by pressure of the pressure medium. The valve member includes a piston and a seat portion facing a valve seat formed in the valve housing. The piston is of the diameter larger than that of the valve seat. A bore connected to the medium supply container is provided in the valve housing which is controlled by displacement of the piston.

Abstract: A force measuring procedure and a force measuring apparatus are used to control the power hoist of an agricultural tractor. The force measuring procedure operates in such a manner that the relative displacement of a point on an elastic system is detected by at least one Hall sensor disposed on either the elastic system or on the fixed frame with the Hall sensor being located in a magnetic field with a predeterminable magnetic flux. For this the force measuring apparatus has a flex rod attached to at least one of a pair of lower hitches which indicates the bending moment, and the Hall sensor is mounted with its detector surface essentially in the primary plane of bending deformation of the flex rod and is connected to the control circuit of the power hoist.

Abstract: A pressure reducing valve comprises a valve housing having an axial bore coupled to a fluid operated load device, and first and second transversely extending control bores coupled to a supply tank and a fluid pressure source, respectively. A control slide is axially shiftable in the axial bore and has first and second pistons controlling fluid flow through the control bores. The fluid pressure supplied to the load device acts on a first end of the control slide. A proportional electromagnet has a plunger which contacts and applies force to the opposite end of the control slide. A first restrictor provides fluid communication between the control slide ends, while a second restrictor provides fluid communication between the control slide opposite end and the supply tank.