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 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: 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: 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: 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 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.

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: In the pressure regulation of a variable displacement pump very high pressures can build up in the pump delivery line if at the consumer no discharge of the fluid takes place, for example the piston of a servo motor moves against a stop. A pressure regulation of the pump is then only possible via the inner losses of the pump. Consequently, although the pressure can be built up rapidly it can only be reduced very slowly. According to the invention the pressure reduction is via a bypass which is controlled by the control valve of the variable displacement pump and which connects the pressure side of the pump to a tank discharge when the control valve is driven in the sense of a reduction of the pump pressure. According to the invention a very rapid pressure reduction is obtained so that the variable displacement pump can again be pressure controlled.

Abstract: The invention relates to a hydraulic vane type pump and to a radial piston pump. The cam ring of said pumps is adapted for horizontal and vertical movement. So as to achieve stable operating conditions for the pump at least within a certain range, a single-piece support body is mounted within the vertical adjustment screw so as to avoid a change in the level of height when the cam ring is moved axially.

Abstract: The invention relates to a vane pump having input and output slot means. Either the input slot means or the output slot means are designed such that for a movement of the cam ring into a position of zero excentricity the area of overlap between the input slot means and the output slot means is increased.

Abstract: In a directional seat valve all the valve seat components disposed axially adjacent each other in the housing bore are held between two closure screws and for assembling the valve the movable valve elements are supported via the valve actuating pin on a punch. By turning the closure screws the valve seat components can be adjusted in the axial direction so that the actuating pin has a predetermined spacing with respect to the housing end side of the valve. An advantage resides in that in the assembly of the valve itself a constant dimension can be set between the actuating pin and the housing and consequently an adjustment on subsequent attachment to the actuating means dispensed with, in particular an adjustment of the actuator cooperating with the actuating pin.

Abstract: For a drive system comprising a hydrostatic adjustable machine an electrical control is provided with which the actuator of the machine is driven so that for acceleration, retardation and braking, i.e. when the machine moves from motor mode to pump mode, a predetermined operating behavior of the machine necessarily results. The particular input desired value for the speed is transformed so that suddenly occurring abrupt acceleration, retardation and braking operations are avoided and in particular on abrupt entry of desired values increased safety against operating errors is achieved.

Abstract: Into the housing of a multiway valve a pressure balance is incorporated, the end of the control piston subjected to the load report pressure facing a housing recess in which the load report pressure obtains while the opposite end of the control piston is subjected to the supply pressure and in the opposite sense to the supply pressure to the force of a spring. The valve has a simple structure.

Abstract: A secondarily controlled hydrostatic machine with variable volume is connected to a line with impressed system pressure which is fed by a primary unit. By switching over the primary unit the secondary unit is subjected to a displacement amount which results in as large as possible a pivot angle of the secondary unit to obtain the highest possible efficiency. The switching over takes place in dependence upon an upper and lower switching point corresponding to the desired pivot angle range of the secondary unit.

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.