Abstract: A positioning drive having a hydraulic motor with a cam disc which is rotatable with a motor shaft and has a cam, a control valve which, with the hydraulic motor forms a unit with a housing and has a valve piston which is displaceable between several positions, a control element via which the valve piston can be supported on the cam disc, and an adjustment element which is operatively disposed between the control element and the valve piston and coaxial to the latter. The relative position between the valve piston and control element is variable by relative adjustment of the adjustment element with respect to the valve piston. The position of the adjustment element relative to the valve piston is securable by a releasable locking element. The outer of the two parts, valve piston and adjustment element, is guided outwards through the housing, and the locking element is accessible externally of the housing.

Abstract: The present invention proceeds from a control arrangement for at least two hydraulic consumers which has a positive displacement pump the setting of which is variable by a load-sensing regulator which can be acted on via a load-signaling line by the highest load pressure, on which a maximum-pressure and an output regulation are superimposed, two displaceable metering diaphragms a first one of which is connected between the positive displacement pump and a first hydraulic consumer and the second between the positive displacement pump and a second hydraulic consumer, and two pressure compensators a first one of which is arranged behind the first metering diaphragm and the second behind the second metering diaphragm and the regulating pistons of which can be acted on, in opening direction on a front side, by the pressure behind the corresponding metering diaphragm and in closing direction on the rear side by the pressure in the load-signaling line.

Abstract: A hydraulic unit having a hollow oil container which has a receiving space for oil between an external outer wall and an internal outer wall, and having a pump unit which comprises an electric motor and a pump which can be driven by the electric motor. Such a hydraulic unit is to be further developed in such a manner that it has only a low noise level, in which connection also sufficient cooling of the hydraulic fluid and of the electric motor should be assured. This is achieved in the manner that at least the pump, and preferably the pump unit, is included in an enclosure which is formed by the hollow oil container and at least one sound-damping element.

Abstract: The invention relates to a servo hydraulic force controlled system comprising a cylinder, a control valve and a controller as well as a load defining the controlled system. The optimum setting of the controller is automatically performed by using a fuzzy-set-logic, wherein the characteristics of the controlled system must be not known. According to the invention the step response of the controlled system is evaluated with respect to certain geometrical characteristics by means of a fuzzy classificator communicating with a ruling unit which correspondingly varies the control parameters. According to the invention, certain characteristics of the step response are thus used for the fuzzification and the optimizing procedure takes place in a predetermined setting order.

Abstract: A proportional valve has an output proportional to an electrical input signal. In a preferred embodiment, the valve is actuated by a proportional solenoid having a coil which is controlled by a control signal in proportion to voltage or current. The proportional solenoid is controlled by a relatively high current such as a rectified mains voltage. A control circuit ensures that the coil of the proportional solenoid is not overloaded. Particularly, it ensures that a maximum current value is not exceeded. In this way, the mains supply required in prior art devices may be eliminated.

Abstract: A control system for a variable-displacement hydraulic pump having an adjustment device and being electrical current-adjustable as required for supplying pressure to a first hydraulic apparatus (13), and pressure-adjustable for supplying pressure to a second hydraulic apparatus (14), in which case the pressure rating and the setting of the pilot valve controlled by the second hydraulic apparatus (14) may be programmed by a control signal. The control system includes a first control valve (18) that can be actuated by the weight of the load of the first apparatus (13) and by a spring (23) when switching to a higher displacement, or by the pump pressure when switching to a lower displacement. The system further includes a second control valve (19) which can be exposed to a force corresponding to the control signal (25) when switching to a higher displacement, or to the pump pressure when switching to a lower displacement.

Abstract: A one-piece axial seal is provided for sealing a passage at the interface between a first component and a second component, in particular a fluid conduit or a screw hole. The seal has a fastening section, comprising a projection adapted to be pressed into a bore provided in the first component, and a sealing section. So that the axial seal can take up an exactly defined position on the first component, the sealing section is prestressed in a direction towards which the projection extends.

Abstract: An injection system for an internal combustion engine having a plurality of cylinders is known which has a hydraulic pump with a delivery outlet to which a delivery line common to the cylinders is connected, and a plurality of injection units each of which is associated with a different cylinder and, in normal drive operation, can be controlled pulsewise by connection with the delivery line. There is also known an exhaust-brake system having a plurality of decompression valves each of which is associated with a different cylinder and, in brake operation, can be controlled pulsewise outside the exhaust stroke, in particular at the end of the compression stroke, by alternate pressure action on and pressure relief of the hydraulic actuating element. The purpose is to create a system with which, at little expense and at favorable cost, the "injection" and "exhaust-brake" functions can be satisfied.

Abstract: The present invention proceeds from an engine brake for a multi-cylinder internal combustion engine with decompression valves actuatable by pressurization of hydraulic pistons outside of the exhaust stroke of the working piston of the internal combustion engine, in particular at the end of the compression stroke. A radial piston pump is provided with internally supported radial pistons. The pump housing has a first housing section with the radial pistons, and a space for the eccentric which controls the radial pistons and a second housing section with the control outputs.

Abstract: In an underground storage space, particularly for endangered goods, access is effected via a left the opening of which, leading into the storage space, can be closed by two covers which are arranged spaced apart from each other.

Abstract: The invention is based on a hydraulic system, in particular of an engine brake for an internal combustion engine, having at least one hydraulic actuating element, a positive displacement pump by which pressurized fluid can be pumped from a low-pressure region into a high-pressure region, and a distributor unit (14) having a control output (13) which is connected via a control line with the actuating element, which control output can be pressurized from the high-pressure region and connected to the low-pressure region. In order to obtain the desired control of the actuating elements over a wide range of cycle times and speeds of rotation of the internal combustion engine with a pump of relatively small displacement, a return valve which opens towards the high-pressure region is provided, via which the control line can be connected to the high-pressure region after it has been pressurized from the high-pressure region and before it is connected to the low-pressure region.

Abstract: In a power-brake system, a hydraulic pressure generated by means of a pump may be supplied, controllably in proportion to an actuation force via brake conduits, by a power-brake valve to individual brake cylinders. Control pressure conduits are connected to the brake cylinders or the brake conduits in the vicinity of the brake cylinders and these control pressure conduits are connected to the brake valve. The brake pressure at the brake cylinders may be fed back, via the control pressure conduits, as the control pressure for acting on the control end of the brake valve so that a control of the control plungers of the brake valve is carried out corresponding to the brake pressure build-up at the brake cylinders and, particularly when low brake pressures are desired, rapid pressure build-up times in the brake conduits are ensured.

Abstract: A hydraulic control device having a directional valve by means of which the direction of movement and the speed of a hydraulic consumer, especially a mobile working device can be modified. The hydraulic control device has a hydraulic pre-control device by which a control pressure can be applied, via a first control line, to a first control chamber and, via a second control line, to a second control chamber of the directional valve, and having valve arrangement in a first control line by which a largely free flow of control oil is admitted to a first control chamber and by which, by a throttling of the discharge of control oil, the movement of a control slide of the directional valve can be damped.

Abstract: A hydraulic drive system includes a first driven hydrostatic machine adjustable in volume and operating as a pump supplying fluid to a supply line for maintaining an impressed pressure therein, a second hydrostatic machine which is adjustable in volume and is connected to the supply line, a valve determining the direction of rotation and the speed of the second machine by adjusting a control flow defining a desired speed value, a signal generator coupled to the second machine for generating a control flow defining an actual value of the speed, a pilot controlled valve for comparing the actual value control flow and the desired value control flow and generating a pressure difference therebetween, and an adjusting cylinder controlled by the pressure difference for setting the pivotal angle of the second machine. To increase the load stiffness and stability of the control system a hydraulic compensating volume is connected to either side of the signal generator.

Abstract: A circuit arrangement for controlling the output torque of a hydrostatic machine connected to a hydraulic system having an impressed operating pressure. The circuit arrangement has a control element for changing the output torque of the machine based upon operating parameters corresponding to pressure, speed, temperature and the like. Control means are supplied with a desired torque value for generating a control signal for actuating the control element. Pick-up means are connected to the control means and to the control element for picking up a pivotal angle .alpha. or an eccentricity E, respectively, representing an actual displacement volume of the hydrostatic machine. The pivotal angle .alpha. and the eccentricity E are measured in either an analog or a digital manner. When measured in an analog manner, the desired value of the pivotal angle is .alpha.=M/P and the desired value of the eccentricity is E=M/P, where M is the torque and P is the pressure.

Abstract: A hydraulic circuit for supplying a plurality of series-operated consumers of a hydraulically controlled installation, in particular of an injection molding machine, having a pump with feed-flow pressure control, is described. To be able to slow down greater moving masses with very little expenditure in regard to circuitry and devices, only a portion of the consumers, such as the extruder, the injection unit and possibly the ejector are operated in open circulation, while at least one selected further consumer, such as the clamping unit of the injection molding machine, where a greater mass must be moved in alternating directions, is moved in semi-closed or closed circulation.

Abstract: A constructional unit comprising a hydraulic machine having a drive or driven shaft and of a support by which the hydraulic machine is held with the interposition of material which deadens solid-conducted noise. Low noise emission of the hydraulic machine is obtained in the manner that the support extends over the hydraulic machine in particular in the direction towards the shaft and that the hydraulic machine is supported on the support via material which deadens solid-conducted noise, present between its outer wall surface and the support. In this way the noise emission can be reduced in a simple manner.

Abstract: A control arrangement for at least one hydraulic consumer in which the consumer can be controlled with respect to direction and speed via a directional control valve device, in which two consumer lines lead from the directional control valve device to the consumer, each of which consumer lines can be connected to a pump and a tank respectively via a directional control valve piston and a metering restrictor and in which a throttle valve having a servo-piston is associated with each consumer line. The consumer is to be held free of leakage oil in a given position.

Abstract: The present invention provides for a control apparatus for independently operating at least two users. The users can be the tilt cylinders and the lift cylinders of a loader. The control apparatus provides for the adjustment of the control valves and for the adjustment of the pressure control apparatus of the variable displacement pump means in dependency of each other. In accordance with the invention, the control position of the control spool of the control valve controlling the user with the largest load provides for a measure (or for the adjustment) of the pressure control device of the variable displacement pump. In this manner an extremely effective and economic operation of the hydraulic system comprising the control apparatus and the users is obtained.

Abstract: The invention relates to a drive for a press, in particular for a sheet metal forming press, the press including a press ram which can be moved up and down and a hydraulic movable counter support. The counter support can be moved in a forward stroke in the direction towards the press ram via at least one hydraulic cylinder by a first hydrostatic machine, and in a return stroke by the press ram. In known presses, during the return stroke of the counter support, the pressure medium is displaced from the hydraulic cylinder while a predetermined pressure is maintained by means of a pressure relief valve (pressure limiting valve) or a throttle valve (flow control valve). The balance sheet of energy of such a drive of such a press is to be improved. This is achieved by providing that the first hydrostatic machine is a pressure controlled machine, preferably an axial piston machine. Preferably, the axial piston machine can be swiveled in both directions, i.e. pivoted towards both sides.