Abstract: A hydraulic control valve (1) is assigned to a pressure line (13) led from a pressure medium source to at least one load. The control valve has a first position in which the pressure line (13) is pressurized by the pressure medium source and a second position in which the load connected to the pressure line (13) is depressurized. The control valve (1) is directed toward the first position by an actuating device (17) and toward the second position by a restoring device (11). The control valve (1) has a safety function such that the pressure line (13) can be depressured to a container, irrespective of the position of the control valve (1). The safety function can be a valve function (20) integrated in a control slide (3) of the control valve (1).

Abstract: The invention relates to a hydraulic control valve (1) which is assigned to a pressure line (13) that is led from a pressure medium source to at least one load, and has a first position, in which the pressure line (13) can be pressurized by means of the pressure medium source, and has a second position, in which the load connected to the pressure line (13) can be depressurized, it being possible for the control valve (1) to be acted on in the direction of the first position by means of an actuating device (17) and in the direction of the first position by means of a restoring device (11). The object, with little expenditure, of permitting the load to be depressurized in the event of a functional fault of the control valve, is achieved according to the invention in that the control valve (1) has a safety function by means of which, in the event of a functional fault of the control valve (1), the pressure line (13) can be depressurized to a container, irrespective of the position of the control valve (1).

Abstract: A track-laying vehicle has two tracks, each with a hydrostatic drive unit, where at least one drive motor 1, 2 adjustable in working volume is provided in each drive unit and to which at least one pressure medium supply line 3, 4, 5, 6 connected to a hydrostatic pump leads and which has a working volume adjusting device 9, 11, 10, 12 that can be influenced by a signal dependent on the operating pressure. To avoid unintentional changes in direction of the track-laying vehicle in the case of different resistances to the tracks, it is proposed to connect the pressure medium supply lines 3, 4, 5, 6 of all the drive motors 1, 2 to a shuttle valve circuit 32, 33, 34 which determines the highest of the operating pressures of the hydrostatic drive unit and empties in a signal line 19 that is connected to the control elements of the working volume adjusting devices 9, 11, 10, 12 of all the drive motors 1, 2.

Abstract: A control device for a variable displacement hydrostatic machine having a stroke-volume regulator which is responsive to an actuating pressure. The control device includes a booster pump. The delivery pressure of the machine is the actuating pressure unless the delivery pressure of the machine is insufficient in which case the actuating pressure is a feed pressure produced by the booster pump. The control device includes a plurality of delivery-pressure lines and a proportioning pressure regulator having an outlet pressure which is proportionally reduced relative to the intake pressure connected between each delivery-pressure line and the stroke-volume regulator.

Abstract: A pump assembly including a primary power source and several axial piston pumps is disclosed. A connection flange is provided on the primary power source on which a first axial piston pump is connected. At least one more axial piston pump is coaxially connected on the connection flange. In order to support the multipump assembly stress-free and pinch-free without special adjustments, it is proposed to fasten at least approximately vertical guide or support plates on at least one and preferably both sides of the first axial piston pump at the connection flange of the primary power source and to connect the plates through an intermediate flange housing with the additional axial piston pump that is connected coaxially with the first axial piston pump.

Abstract: In an adjustable axial flow piston pump having a swivellable component such as a swash plate, pressure chambers for swivelling the swivellable component, a lever connected with the swivellable component and supported in the housing of the pump, a final control member mounted in and movable in the lever, a fluid passage in the lever supplying fluid pressure to the control member, a fluid passage in the pump housing connected to the pressure chamber and a fluid passage in the lever connecting the control member and the fluid passages in the housing whereby fluid pressure is delivered through the lever and control means to the pressure chamber.

Abstract: A hydraulic system having at least two pumps including a variable-displacement pump and a constant-displacement pump, both driven from a common prime mover, includes a control-pressure pump operated by the shaft of the prime mover and operating with its input a valve which controls the pressure of a control piston acting upon a spring which bears upon the control member in a direction opposite to its setting piston. A cylinder of the setting piston is connected to the output of the adjustable-displacement pump.