Abstract: A pump supplies via in each case a directional valve with associated pressure balance fluid or pressure medium to a plurality of loads. When the pump power is not sufficient a proportional quantity reduction is achieved at all loads in that the control voltages of the control members for electrical actuation of the directional valves are supplied to a summation stage and the sum voltage is compared in a comparison stage with a limit value corresponding to the maximum pump displacement, whereupon when the limit value is exceeded a control signal is generated with which the stroke of the driven directional valves is reduced.

Abstract: In a radial piston machine which includes a driven rotatable rotor with radial pistons displaceable in radial recesses of the rotor by pressure medium and carrying rollers which cooperate with a cam track of the rigid cam plate, the length of the rollers can be increased due to the provision in the bores receiving the rollers respective opposing recesses in which portions of the roller are received.

Abstract: The invention relates to a three-way pressure reducing valve for reducing a primary pressure to a secondary pressure. Said three-way pressure reducing valve comprises means for monitoring the secondary pressure. First spool means of said pressure reducing valve and second spool means of said monitoring means are provided with first and second spring means, respectively. Further, first and second adjustment means, respectively, are provided said first and said second spool means being coaxially arranged.

Abstract: A plurality of mechanically coupled secondarily controlled hydrostatic machines with variable volume are connected to a line with impressed system pressure fed by a primary unit. By reducing the variable volume to 0 in individual hydrostatic machines the remaining machines are subjected to a higher torque which results in a greater pivot angle of the remaining secondary units. As a result the efficiency and controllability are improved. The changeover is effected in dependence upon an upper and lower switching point corresponding to the pivot angle of the unit remaining in engagement.

Abstract: A control block is made up of a plurality of directional valves which serve to actuate a plurality of hydraulic drives to which in some cases a different pressure is to be supplied. For this purpose two pressure-limiting valves adjustable to different pressures are provided, the valve adjustable to the lower pressure being connected to the last valve unit. This gives a simple construction and substantial freedom in the association of the drives.

Abstract: The invention concerns a hydraulic system for supplying a hydrostatic steering system. A central variable capacity hydraulic fluid pump supplies the steering system and a secondary consuming device via separate respective compensated pressure maintaining valves. The steering system and secondary consuming device are controlled by respective load report lines which are brought together at a changeover valve which is operative to permit the higher reported pressure to be delivered to a volume governor for the pump. Upon the secondary consuming device entering a neutral condition or a fluid loss condition, the changeover valve moves to block the load report line to the secondary consuming device; and a control circuit, including a branch line from the feed line to the steering system, maintains a higher pressure in the load report line of the steering hydraulic circuit than in the line of the secondary consuming device.

Abstract: In a plastic processing machine (injection moulding machine) the amount of working medium to be supplied to the hydraulic drives and to the injection cylinder and the clamping cylinder is regulated to control the adjustment rates via a quantity control of an adjustment pump. The setting of the pressures necessary at the drives is effected in contrast via a directional valve which controls the fluid paths to one of the drives and which is adapted to be connected to the tank via a regulatable throttle point governing the pressure. This simplifies the apparatus expenditure for the pressure control of such a machine.

Abstract: A pump supplies via in each case a directional valve a plurality of consumers with fluid, a pressure balance for load-independent division of the pump displacement being provided between each branch line branching off the pump delivery line and the directional valve. In a pressure regulating valve common to all pressure balances a control pressure is generated from the pressure difference between the pump pressure and the respective highest consumer pressure and is applied to all the pressure balances so that when the pump power is inadequate a proportional quantity reduction at all consumers is achieved.

Abstract: An adjustable hydrostatic machine is connected to a pressure line with impressed system pressure. The pressure difference applied at the machine is set at a control valve so that the stroke volume of the machine in idling operation is set to an adjustment belonging to a predetermined load torque. In idling operation the machine is thus operated at large stroke volume with small pressure difference. If it is then necessary to furnish the load torque a switching valve is opened so that at the machine the full pressure difference is immediately applied, the machine can furnish the desired torque and the time loss necessary for setting the machine is eliminated.

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: A compensating valve arrangement is connected between a throttling direction control valve or proportioning valve which controls fluid flow from a pressure source to a load. The compensating valve is provided with a pressure reducing valve, check valves and throttling points between the pressure supply and the control piston of the compensating valve to compensate for surges, prevent sudden driving of the load and prevent leakage.

Abstract: A control for the speed of rotation of a hydrostatic machine in which the controlled variable and generated in a speed controller and is made up of a proportional component and an integrating component is limited by a limiting signal which is also made up of a predetermined basic value and a ramp signal behaving proportionally to the actual pivot angle of the hydrostatic machine. The limiting signal thus limits the output signal of the speed controller so that a rapid response behaviour is obtained and fluctuations in the settling to the desired speed are reduced.

Abstract: A safety circuit which is essentially for supplyng hydraulic loads. Briefly stated, this circuit has a control pump which, via a priority valve, supplies hydraulic power to a power steering hydraulic circuit and at least one other load hydraulic circuit on a priority basis where the power steering receives the highest priority. Also provided is a control circuit which limits the intake pressure of the control pump and has a safety valve associated with it which is controlled by the intake vacuum of the control pump. This valve effects a reduction of the pump output when pressure in the suction line from the hydraulic fluid storage container drops below a minimum pressure.

Abstract: A 3/2 directional poppet valve is provided having a pilot poppet valve and a main valve. Said main valve comprises a housing having a longitudinal bore within which two 2/2 cartridge or logic valves are arranged in an axially opposite manner. A spool is provided in each of said logic valves. The diameters of said spools being different and the front ends of said spools facing towards each other can be mechanically coupled such that the movement of the one or the other spool into the closing position causes a movement of the other spool out of its closing position.

Abstract: A tool, in particular a lapping wheel, is to be positioned by a hydraulic drive cylinder and subsequently pressed against a workpiece. For this purpose a position control and a pressure or force control is provided. The weight change of the lapping disk subjected to wear is automatically detected by measuring the pressure value which is necessary to keep the weight in a state of suspension without support. The pressure value is stored and in the subsequent pressure regulating operation fed as compensating parameter to the pressure control circuit.

Abstract: In the supply of priority and lower-ranking consumers the flow to the priority consumer must be maintained even when there is a leak in the hydraulic system of the lower-ranking consumers. For this purpose the priority consumer is connected via in each case a check valve to a pump and an auxiliary pump. If the pressure generated by the pump drops for example due to a leak a valve opening the pressure line to the discharge is shut-off and the priority consumer thereby supplied with fluid delivered by the auxiliary pump.

Abstract: Proportional magnet having a housing in which an armature bar is mounted which is movable under the influence of an armature winding arranged in the housing, wherein a hydraulic unit serving to operate the armature bar is additionally provided.

Abstract: In a brake valve of the type in which a given ratio is maintained between a master pressure developed by a brake pedal and an actual brake pressure, an arrangement is provided for continuous, rather than stepwise, adjustment of this ratio. The brake valve includes a control piston which is subjected to the master pressure and which, by the displacement thereof, opens and closes connecting channels between an accumulator containing a primary pressure fluid and a brake, as well as between the brake and a fluid collecting tank. The control piston and a measurement piston apply counter forces to the arms of a balance beam whose lever ratio determines the degree of feedback of the instantaneous brake pressure to the control piston. A stop is provided in the path of the axis of the control piston, which limits the stroke of the piston, to prevent the overloading of the balance beam during abnormally high braking pressures such as occur, for instance, during panic braking.

Abstract: A directional control valve comprising a valve housing, tank-, user-, and pump-ports provided in said housing, a spool reciprocally mounted in said housing and adapted to connect and/or separate said ports, and a pilot controlled flow control valve within said directional control valve.

Abstract: A radial piston machine includes a stationary cam plate and a rotational cylinder block provided with radial bores receiving a plurality of radial pistons displaceable in those bores and supported against the cam plate surrounding the cylindrical block by rollers. Each piston has in the region of supporting the roller a web which is cured and supported in one of the grooves formed in the cam plate.