Abstract: An automatic control including a memory is provided to be loaded with positional data for the automatic control of a cycle of motions of preferably a plurality of power members. The speed reading the data in and out is freely selectable. Accordingly programming a cycle of motions may be performed in a slow motion process, whereas the speed of reading out the data is selected such that an optimum operational speed is obtained. In addition to the automatic speed control a manual control is provided to interrupt the cycle motion of the automatic control to manually adjust the position or the power member. In returning to the automatic control the further cycle of motion is taken up again where it has been interrupted.

Abstract: A process is described for application of pressure on setting mechanisms of transmission elements, e.g., band brakes or disk clutches, of an automatic transmission, particularly of the transmission system of a vehicle. In the process the control pressure applied to the setting mechanism is varied in dependence on the operating conditions. In order to eliminate transition errors and improve adaptation of the meshing behavior of the switching element, the slide of the switching element is regulated at a value adapted to the operating condition involved of the transmission and/or the vehicle. Apparatus for the implementation of the process is also described, as well as a hydraulic control system for supplying the operational chamber of a setting mechanism at a transmission element, which operational chamber has a continual leakage.

Abstract: Braking apparatus, in particular braking apparatus, using discs for use together with a rotary disc support adapted to support a first set of discs. A brake housing is provided which support a second set of discs which are interdigitating with the first set. A brake piston is located in an opening of the brake housing in a reciprocable manner. A Spring biases the brake piston towards the first and second sets of discs. Separately from the brake piston a cover mounted at the brake housing is provided.

Abstract: Described is a control circuit for a hydraulic power lift driven by a displacement pump which has a check valve releasable at least for lowering movements of the power lift, a actuation means switching the check valve off and on to control the flow from a pump line into an operating line leading to the power lift and vice-versa, and a load-sensing line carrying the load pressure and connected to the operating line, by which the variable-displacement pump is capable of being activated. The actuating means has an actuating unit switching the check valve off and on and a servo valve, activated simultaneously and controlling the flow to and from the power lift, with at least three switch positions. In the starting position of the actuating means, the latter connects the load-sensing line and the operating line, by way of the servo valve, with the tank and, after passage through a central position, the operating line with the pump line.

Abstract: A proportional directional control valve in combination with a pressure compensator flow rate control valve opening towards a reservoir and a pressure unloading valve in the load- pressure- carrying control line for the compensator valve are provided to actuate the telescopic cylinder of a tipper truck. The valve device is connected to a pump of constant displacement. The operating speed of the telescopic cylinder is independent from the load to be lifted and the driving speed of the pump. Upon reaching a predetermined load pressure the pressure unloading valve is activated and the load pressure engaging the compensator valve towards closing direction is reduced via the reservoir such that the compensator valve opens and the pump displacement volume returns to the reservoir.

Abstract: For the relief of a highly pressurized hydraulic liquid in a working chamber of pilot controlled 2/2 poppet valve is used. The working chamber is further connected to a pressure relief valve, the output of which is connected to a control conduit extending between a control chamber of the 2/2 poppet valve and the pilot valve. The apparatus of the invention requires a shorter period of time for the pressure relief without the danger of relief noise.

Abstract: The present invention provides a pilot operated pressure reducing valve in which the pilot liquid (generally the pilot fluid) is taken from the low pressure side, wherein two pilot liguid connections (or conduits) from the low pressure side to the pilot valve are provided which the separate from each other. The one connection takes the pilot liquid (or fluid) from the control area of the control spool while the other connection takes the pilot liquid (or fluid) from outside the control range (or area) of the control spool. A check valve is provided to seperate said two connections and closes to the low pressure side. Thus, even for large volume flows and large pressure differentials, between the high pressure side and the low pressure side, good control- and stability characteristics are obtained.

Abstract: Disclosed is a preferably electrohydraulic control for a load-dependently operating variable displacement pump, which is equipped with a differential pressure control device for ensuring a predetermined pressure drop at the control edge of a directional valve integrated into the consumer supply line. The differential pressure control device has a servo valve, the valve spool of which can be brought out of a first position, increasing the output volume of the variable displacement pump, against the compressive force of a spring and of a control pressure led off from the supply pressure upstream of the directional valve, by the pump pressure into a second position, reducing the output volume.

Abstract: A valve comprising a valve housing, a bore in said valve housing, annular grooves defining annular channels arranged in said valve housing and adapted to be connected to valve ports arranged in said housing, a control spool reciprocally mounted within said bore so as to connect and separate said valve ports, and land means in at least one of said annular channels so as to block the rotation of said control spool, said land means extending into said at least one channel transversely to the direction of flow of the pressure medium, said land means extending substantially radially into said annular channel.

Abstract: A directional control valve is provided which can be switched into one of its switching positions only after the operator has supplied an additional signal.

Abstract: A hydrostatic drive system consists respectively of an adjustable primary and secondary unit which are connected together via a conduit train with impressed pressure. The volume flow of the primary unit is regulated in dependence upon the impressed pressure and the volume flow of the secondary unit as a function of the speed. To avoid pronounced dropping of the impressed pressure the power of the secondary unit is limited. For this purpose a circuit is provided in which the volume flows of the primary and secondary units are compared. The power limitation intervenes when the volume flow of the secondary unit exceeds the volume flow of the primary unit.

Abstract: A hydraulic circuit comprising a control pump having first and second adjustment means for changing the output volume of fluid pump, and a regulating valve adapted to suppy user means with a pressurized liquid.

Abstract: In the neutral position of a directional control valve in which the connection of the constant pump to the consumer is interrupted the entire delivery of the constant pump is led via a bypass valve to the tank. According to the invention the regulating range of the bypass valve is increased by an additional connection which is controlled by a further piston which in the neutral position of the directional control valve is displaced by a weak spring into the open position and thus ensures a pressureless circulation of the pump working medium to the tank.

Abstract: A control device transmits hydraulic pressure from a continuously circulating pump to a hydraulic device. A pressure limiting valve communicates with the pump to exhaust the pump to reservoir when the system is in a stand-by mode. The control device includes a servo valve and a directional control valve. Movement of the latter relative to the former is possible in order to create a pressure back-up in a load indicating line which closes the pressure limiting valve, thereby increasing the pump pressure supplied to the servo valve when it is desired to initiate a working mode. Subsequent actuation of the servo valve causes hydraulic pressure to be supplied to or exhausted from the hydraulic device. Actuation of the servo valve is produced by hydraulic pressure which also communicates with the load indicating line via a one-way valve.

Abstract: A hydraulic lift is raised by hydraulic fluid which passes through a servo valve and is lowered when the servo valve exhausts the hydraulic lift to a reservoir. The hydraulic fluid travels to and from the lift through a service line in which a blocking valve is disposed. A control unit opens the blocking valve against a spring bias in response to the application of a control pressure to a control element disposed on one side of the control unit. The control pressure is supplied via a control line which also actuates the servo valve. A branch control line branches from the control line and applies pressure to another control element which acts counter to the first-mentioned control element. The branch control line includes tow throttles between which a discharge line is connected and communicates with the reservoir.

Abstract: The invention refers to a pilot controlled pressure relief valve comprising a pair of fluid ports to be operable in both directions of flow. The pressure relief valve is provided with a single pilot control valve 24 which allows for an equal actuating pressure in both flow directions.

Abstract: An inductive distance detecting circuit has a control circuit, an inductive distance detector, and an evaluation circuit (demodulator). The control circuit is an LC- oscillator which comprises a parallel circuit having a capacitor and which uses coils of the inductive distance detector, connected in series. An operational amplifier uses the capacitor and coil to determine distance.

Abstract: A control motor for a servo valve which includes pole screws defining an armature space, first and second coils supported by the pole screws, respectively, a soft metal armature which is resiliently mounted to a thin walled tube and a permanent magnet which polarizes the armature. An annular body carrying said pole screws and providing for a magnetic path between the pole screws and the permanent magnet.

Abstract: The invention relates to a control circuitry for a solenoid operated control valve. The invention provides for a simplified means to obtain a constant valve gain and thus a linear valve characteristic by stepwise varying the gain of the input signal to control the stroke of the valve piston. The non-linear valve gain is first measured to obtain gain correcting values which are stored in a table store corresponding to predetermined values of the input signal for controlling the valve. This input signal is delivered by a commercial CNC-control. The input signal is varied by the correcting means so that the input signal is increased in the zero-flow-range of the valve for example. Assuming that the pressure difference across the valve is constant there will be obtained a linear flow characteristic for the valve. The resolution of the corrected input value is responsive only to the resolution of the CNC input valve as the input value is continuously corrected by multiplication between its incremental steps.

Abstract: A container is suspended from four hoist ropes. One end of each rope is wound on a drum to be driven in either direction to hoist or lower the container. The second end of each rope is connected to a double acting hydraulic cylinder. The cylinders are controlled by a valve system to dampen swaying of the load to reset the ropes and for skewing, trimming and listing the load.