Abstract: A directional control valve has snap-locking device for retaining the slide of the directional control valve in at least one switching position. The snap-locking device has a snap-locking part with a snap-locking piston that allows an engagement part to engage and lock the slide of the directional control valve. A kick-out device disengages the engagement part when a predetermined control pressure is exceeded. The kick-out device triggering force may be adjusted by a setting device that acts on a kick-out spring. A switching device that allows the kick-out function to be switched off independently of the setting of the setting device associated with the directional control valve in order to prevent disengagement independently of the initial stress of the kick-out spring.

Abstract: A load valve apparatus having a control valve which can be connected to a pump and an accumulator and which in a first position connects the pump to the accumulator and in a second position isolates the pump from the accumulator, and the pump and the accumulator are isolated from one another when the accumulator pressure exceeds a certain value, and a connected consuming device is isolated from the accumulator in such a way that the load pressure of the consuming device does not affect the accumulator. The pressure of the pump and/or of the accumulator is used to regulate the pump.

Abstract: The present invention relates to a control system for hydraulic power units, in particular hydraulic cylinder-piston-assemblies comprising a valve to be controlled by an electronic controller, the valve controlling the fluid path between the power unit, a pressure source and a reservoir. A pressure sensor and a circuit for differentiating the sensed pressure quantity in response to time is provided for sensing a respective output variable of the power unit. The pressure variation signal is utilized to assist operating the valve to improve the control operation, i.e. to dampen fluid vibrations or to decrease the hammering noise produced in the operation of stamping, nibbling or shearing machines.

Abstract: The invention relates to a drive system for a hydraulic press. The drive system is of the type of secondary controlled system maintaining an impressed pressure of substantially constant magnitude in a pressure system. A hydraulic transformer comprises a pair of mechanically coupled hydrostatic machines each having a variably capacity. The first machine is connected to the pressure system and the second machine to the press cylinder. The invention provides a drive system in which biasing the press cylinder, rapid tranverse and pressing stroke, decompressing the fluid and flushing of hot fluid is accomplished in a closed loop free of throttling losses. The hydraulic transformer further allows to recover energy to the pressure system.

Abstract: A control for a hydraulic drive or actuator is provided, wherein the actuator has pressurized operating fluid applied thereto, and wherein the operating fluid is directed through an electrically controlled valve for establishing the amount of operating fluid to be fed to the actuator. An electrical signal for controlling the valve is provided by a computing device. In the computing device, a predetermined desired value for the position (or travel), force, or pressure of the actuator or drive is continuously calculated based, at any given time, at least on one measured or simulated state variable indicative of a condition of the drive or actuator at the time of calculation. The calculated desired value determines the amplitude of the electrical signal directed to an electrical actuating device of the valve. The computing speed of the computing device for determining the respective desired value is faster than the actuating velocity or speed of the valve.

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 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: 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: A hydraulic gear machine, in particular an internal gear machine having two gear wheels which mesh with each other in a chamber of a multipart housing, a sealing plate arranged on the side of the two gear wheels axially between them and a housing part, and a pressure field which is present in the housing part on the high-pressure side, is open towards the sealing plate, and is adapted to be acted on by high pressure. The order to provide embodiments of the gear machine which differ in their direction of rotation with the use of many of the same parts, a second pressure field is present in the housing part and the first pressure field is present only on the one side and the second pressure field only on the other side of a center plane which is defined by the axes of rotation of the two gear wheels so that a piece of the housing part is still present between the two pressure fields.

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.