Abstract: An adjustable hydrostatic pump (10), in particular a piston pump, is proposed, whose cam ring (22) is adjustable via a hydromechanical adjusting assembly (35) and which has a device for active noise abatement. A pressure chamber (39) of a adjusting piston (37) acting upon the cam ring (22) is acted upon by pressure changes, via an additional control unit (47) parallel to the hydromechanical pressure controller (41), in such a way that the oscillating actions of power-train forces on the hydraulic fastening of the cam ring (22) are reduced, thus lessening the noise produced by the piston pump.

Abstract: An electro hydraulically adjustable pump has an adjustment member which is adjustable by at least one adjustment piston, a control valve which acts upon the at least one adjusting piston, a servo amplifier which triggers the control valve and which is supplied with an actual value of a pump adjustment and an actual value of a control valve adjustment, and an element which produces an additional pulse-shape adjusting signal as a function of an angle of rotation of the pump so as to control the control valve through the servo amplifier by the additional pulse-shaped adjustment signal.

Abstract: The flow controlling device for a hydrostatic pump has a servo-piston (12) for adjusting the actuating element (11) of the adjustable pump (10) which is acted upon by a control pressure. The latter is controlled by a regulating valve (22) which is acted upon by a pressure differential across a measuring throttle (16) arranged in the delivery line (15) of the pump. Moreover, a pressure spring (23) acts on the regulating valve against the higher pressure. An external pressure supply (26) (pressurized reservoir) is provided for preparing the control pressure. To obtain an accurate, rapid flow control, even for low operating pressures, a connection line (76, 71) connecting the high-pressure side of delivery line (15) to the control pressure connector of the servo-piston (12) is provided, which contains a fixed throttle (72). Alternatively, the regulating valve may be replaced by two spatially separate valves, a flow regulator (80) and a pressure regulator (81).

Abstract: A positive-displacement machine includes a hollow housing provided with two diametrically opposed bores each having a first end communicating with an interior of the housing and a second end closed by a cover. A rotor member is adjustably displaceable in the interior of the housing due to displacement of two pistons positioned in the bores. The pistons are connected to a high pressure chamber, to thereby create in the pistons pressure sufficient to move the latter, to thereby move the rotor member. The housing is provided with control devices to change the pressure in the bores and create a pressure differential in the bores sufficient to move the rotor member into a predetermined position.

Abstract: A control arrangement for a hydrostatic drive comprises a gear pump driven by an internal combustion engine and supplying fluid to a fluid motor. The control arrangement is constructed in such a manner that even at a high number of revolutions per time unit of the internal combustion engine, the fluid motor may be operated at a low number of revolutions.

Abstract: An arrangement for pumping fluids includes at least one variable-output pump and a drive therefor. An auxiliary pump is also driven by the drive and discharges control fluid at a rate corresponding to the speed of rotation of the drive into a discharge conduit in which a variable flow-through cross-sectional area throttle valve is located. The pressure in the discharge conduit upstream of the throttle valve controls the displacement of a control slide between the two end positions thereof in one of which the control slide controls the variable-output pump so as to increase the output thereof, while in the other of such positions of the control slide the pump is controlled so as to reduce the output thereof. The throttle valve is responsive to the pressure in the discharge conduit, but can be arrested in any position thereof when the drive is overloaded so that the flow-through cross-sectional area thereof is fixed, which results in a decrease of output of the variable-output pump when the drive is overloaded.

Abstract: The pump has a regulating element whose position is controlled by means of a first and second piston. The first piston is kept under pressure by the output pressure of the pump. The output side of the pump is also connected to a throttle valve which has a cross-section allowing fluid flow which varies as a function of pressure. The pressure difference created at the throttle valve output relative to the throttle valve input acts on a three-position three-port control valve which control the pressure on the second piston accordingly. The second piston has a larger diameter than the first piston.

Abstract: In a piston machine of the type having a housing, a reciprocable piston in the housing and provided with an axial end portion and a piston-reciprocating element having a glide surface located opposite and movable with reference to the end portion for effecting the reciprocation of the piston, the invention provides for a glide shoe which is articulately connected to the end portion of the piston and which has a glide face in gliding contact with the glide surface of the piston-reciprocating element. The glide face has a recess which communicates via a passage with a source of pressure fluid, a sealing rim of substantially constant width surrounding the recess, and a plurality of face portions which are located outwardly of the sealing rim and configurated so that hydrodynamic pressure fields develop between the face portions and the respectively juxtaposed surface portions of the glide surface.

Abstract: In a piston machine of the type having a housing, a reciprocable piston in the housing and provided with an axial end portion and a piston-reciprocating element having a glide surface located opposite and movable with reference to the end portion for effecting the reciprocation of the piston, the invention provides for a glide shoe which is articulately connected to the end portion of the piston and which has a glide face in gliding contact with the glide surface of the piston-reciprocating element. The glide face has a recess which communicates via a passage with a source of pressure fluid, a sealing rim of substantially constant width surrounding the recess, and a plurality of face portions which are located outwardly of the sealing rim and configurated so that hydrodynamic pressure fields develop between the face portions and the respectively juxtaposed surface portions of the glide surface.