Abstract: The switching time in opening and closing a valve is determined by a closing throttle and an opening throttle which both together are arranged in series with a check valve. For closing the valve the check valve is opened thus making the opening throttle ineffective so that the closing speed is solely determined by the cross-section of the closing throttle. For opening the valve the check valve is closed so that the control pressure is decreased across the opening throttle defining a desired opening speed.

Abstract: A reservoir loading valve accomplishing a pressure protection of the reservoir circuit comprises a pre-control valve subject to the pressure of the control circuit and which controls depending on this pressure a switching valve the piston of which in turn controls the connection between a pump and a working hydraulic and the reservoir circuit. The reservoir circuit is supplied with pressure fluid through a blind bore and a transverse bore in the piston of the switching valve, while a flow control orifice is provided in the blind bore and controls the size of the flow of volume flowing to the reservoir circuit. When the reservoir is loaded and the working hydraulic circuit is connected, the piston of the switching valve will be displaced by the high pressure delivered by the pump into a position in which the connection between the pump and the reservoir circuit is completely interrupted.

Abstract: A hydraulically operated two-way seat type valve includes a housing a forming valve seat, and a locking body displaceable in the housing and cooperating with the valve seat. A cover is mounted on the housing. An actuating piston for actuating the locking body of the valve is guided in the cover. The piston has two opposing piston-shaped extensions one of which is secured to the locking body whereby a non self-closing valve can be switching into the self-closing valve.

Abstract: A control motor for a servo valve which includes pole screws defining an armature space, first and second spools or coils supported by the pole screws, respectively, a soft metal armature which is resiliently mounted to a thin walled tube and a samarium cobalt permanent magnet. The permanent magnet polarizes the armature so that when the spools or coils are energized, the armature will move toward one of the coils and away from the other coil.

Abstract: A method and apparatus for adjusting the working depth of a soil-moving (soil-working, tilling) machine carried by a tractor includes adjusting the position of the machine in relation to the tractor in dependence upon a traction signal and upon a position signal. The traction signal corresponds to the traction produced on the machine in the soil and the position signal corresponds to the position of the machine in relation to the tractor. A portion of the traction signal above a certain cut-off frequency and a portion of the position signal below the same cut-off frequency or below a lower one are utilized in the adjusting control.

Abstract: A fluid operated positioning apparatus includes a multi-position valve operated in response to differential pressure in a fluid control circuit. The control circuit includes two adjustable throttles in series, the junction between the throttles being connected to a control device at one end of the valve. Particular relationships for the throttles are disclosed. Other embodiments include additional throttles for improved control with low pressures.

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: The invention relates to a priority control means with which the actuation sequence of two servo motors can be automated. For this purpose a priority control valve is provided which on actuation of the higher priority control valve immediately blocks the lower priority servo motor. If the priority servo motor has reached a certain position the associated control valve is automatically switched back so that the actuation of the lower priority servo motor then follows automatically. Via a changeover valve the working pressure of the respective servo motor is furthermore automatically switched to the pump control of an adjustment pump or, with a constant pump, to the load-pressure-dependent pressure control so that a load-dependent regulation takes place.

Abstract: A vehicle, such as a tractor, has an attachment implement, such as a plow. An automatic controller acts upon a power lift of the plow, which moves the plow during operation in trenching position. In a first control, this motion of the plow ensues relative to the tractor, so that the vertical absolute velocity component of the plow becomes approximately zero. The plow is so moved relative to the vehicle that it moves upward during a downward motion of the plow-tractor joint and downward during an upward motion of such joint. The tractor is this completely disconnected dynamically from the plow, so that the pitching vibration behavior of the tractor is not subjected to a negative change due to the moments resulting from the forces of acceleration of the plow and affecting the plow, as is the case with a vehicle having a rigidly connected attachment implement. In a second control, the plow is moved in opposite phase to the tractor to counteract a change of its pitching angle coordinate.

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 casting mold with a feeder, particularly for producing cast iron, includes an exothermically heated feeder mass. The casting material in the cylindrical or slightly conical feeder volume of the feeder mass is kept in a liquid state until termination of the drawing in of casting material by suction into the casting cavity. The feeder volume has dimensions corresponding to the quantity of casting material drawn into the mold cavity to compensate for casting shrinkage, plus a miximum security allowance of 30 percent of the quantity of casting material drawn in. To obtain a feeder mass which is less costly than conventional feeder masses, from the point of view of simpler and more propitious temperature measurements, the feeder mass has an outside shape of a flattened sphere, a flattened ellipsoid or a flattened pear. The smallest diameter is on the side away from the casting being produced. The flattening is provided adjacent to the casting.

Abstract: In a priority control device the supply flow to the lower-ranking consumer is set by a flow control valve (pressure balance) whose control chamber subjected to the control pressure of the lower-ranking consumer can be relieved of pressure via a proportional valve. The proportional valve is adjusted in dependence upon the load pressure of the priority consumer so that the flow of fluid to the lower-ranking consumer is throttled by the pressure balance when the pressure difference at the priority consumer drops on increased volume flow requirement. The priority control device thus consists of two simply constructed power valves and a small-dimensioned pilot valve.

Abstract: A parking brake valve cooperates with a spring loaded cylinder which releases a parking brake when pressurized. The valve includes a shaft with an eccentric section, and this shaft may be turned by an actuating lever from a position in which the brake is engaged to a released position. In the released position, the eccentric section of the shaft causes the movement of a control piston, permitting the spring loaded cylinder to be pressurized, releasing the brake. The pressure applied to the spring loaded cylinder is also provided to a radial surface on the shaft, causing the shaft to be friction locked in the released position, despite a spring force applied by a control spring tending to return it to the braking position. If a breakdown occurs in the parking brake system, however, the pressure to the spring loaded cylinder will drop, releasing the friction lock.

Abstract: The invention relates to a driving unit for a feed pump, particularly for a crude oil feed pump which is suitable for recovery of energy. The delivery flow of a hydraulic variable displacement pump, in particular a pump of the axial piston type is used to perform the upstroke of the pump piston. A directional valve control means is provided to deliver the liquid volume displaced under pressure in the downstroke of the pump piston through the pump in the same direction of flow as for the upstroke. The pressurized fluid may either pass to a reservoir, wherein the pump drives a motor for supplying electrical energy back to the electric supply, or, respectively, may load a hydraulic accumulator which is connected to the suction port of the pump for performing the upstroke of the pump piston for which the accumulator is discharged, wherein the remaining torque only has to be supplied by the drive motor.

Abstract: A proportional solenoid operated pressure regulating valve is disclosed. First and second metering spools are respectively mounted for movement inside first and second control spools. Each metering spool responds to a fluid pressure being controlled at a respective operating port.

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 device for controlling an adjustable arm 1 has an operating circuit 10 including a movable valve 3 with two control mechanisms 11, 12 bidirectionally actuated by pressure. A control circuit to activate the movable valve is connected to a pressure source 19, to the two control mechanism 11, 12, and to an adjustable throttle 22 attached to one of the two control mechanism 12. The control circuit also includes an adjustable throttle 24, series connected adjustable throttles 27, 28 attached to the other control mechanism 11 and a fifth adjustable throttle 57. The fifth throttle is used to create an additional actual value input. An adjustable control valve 53 employs the desired and actual value inputs supplied by the adjustable throttles in various ways by interconnecting the throttles with the control devices and a pressure ratio valve 45 so that the system responds to applied force, position or both.

Abstract: The present invention relates to a rotary piston machine comprising a housing which consists of a flange housing, an intermediate housing and an end housing. The flange housing has a flange extending there from landing the machine on a suitable support. A shaft is rotatively supported within the housing, and a rotor is fixedly mounted on the shaft and adapted to rotate together with the shaft. A hollow gear for farming compressing chambers is also located within the housing for cooperation with the rotor. A commutator is fixedly mounted within the flange housing means and is adapted to supply pressure medium to and to remove pressure medium from the compressing chambers.

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: A pressure responsive flow divider valve for servo-powered steering devices comprises a flow control valve having three ports to divide the fluid flow delivered by a pump between a pair of partial volumes, one flowing to the steering valve and the other flowing to a further hydraulic load. When the steering device is not operated, the further load is primarily supplied with fluid, while the flow to the load is reduced, but the steering valve is fully supplied when the steering device is actuated. The valve comprises a valve member which is actuated in response to pressure to change the cross section of the throttle in the flow control valve so that the steering valve is supplied with a relatively small volume of fluid when the steering device is not operated, whereas the valve member is shifted by a pressure increase when the steering device is actuated to supply an increased fluid flow to the steering valve as required. The valve according to the invention allows to reduce energy to drive the pump.