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 piston machine, particularly a radial piston machine which includes a pintle supporting a rotor which has a plurality of radially extending bores in which radial pistons are guided. These bores are in communication with control chambers formed in the pintle. One of the chambers is a high-pressure chamber and the other is a low-pressure chamber. Pre-control grooves and additional passages are provided at the control chambers to prevent, during the operation of the radial piston machine the occurrence of pressure shocks at the inner and outer dead centers.

Abstract: An arrangement for regulating supply flow and limiting supply pressure of an adjustable pump, has a flow regulating valve, a control spring and a throttling element for controlling the flow regulating valve and arranged so that a primary pressure takes place upstream and a secondary pressure takes place downstream of the throttling element so as to form a pressure differential, an adjusting member operative for adjusting the pump and controllable by the throttling element, a servo element operative for forming communication with a pressureless space in the event when the supply pressure exceeds a predetermined value so that the pump is adjusted back to a smaller supply, as second throttling element arranged to bring the secondary pressure to the flow regulating valve, and a third throttling element arranged to vary the secondary pressure, connected in series with the servo valve, and first operating when the latter is open.

Abstract: A power regulating device for a hydrostatic pump with at least one pressure-loaded piston which adjusts a stroke-varying member and is controlled by a valve with two springs acting upon one side of the valve and a gauge piston loaded by the delivery pressure and a lever through which a force proportional to the delivery pressure acts upon the other side of the valve, is provided with an additional spring which acts upon the gauge piston via an intermediate member in the same direction in which the delivery pressure acts, and with a second pressure medium source arranged to act with a variable control pressure upon the intermediate member against the additional spring.

Abstract: A control system for maintaining the product of the lifting pressure and lifting volume times flow constant in an adjustable pump having a regulating member acted upon by two pressure-controlled pistons. The device includes a control valve which is operatively connected with a spring with a linear characteristic, which spring is through the control valve operatively connected to an adjusting lever having an arm which is varied proportionally to the working pressure of the pump. The moment is produced by the force of that spring and that variable lever arm. A counter moment is generated by a force of a second spring and a second arm of the adjusting lever. Upon creating the force equilibrium on the adjusting lever the control valve is so controlled that the product of the pumping pressure and pumping volume times flow remains constant. The control valve controls one of the two pressure-controlled pistons which adjusts the stroke of the regulating member.

Abstract: An arrangement for regulating the output flow and the output pressure of an adjustable pump includes two parallel throttles arranged, respectively, in an output conduit and in a branch conduit; a spring biased multi-way directional control valve is controlled by differential pressure in the branch conduit upstream of the two throttles to adjust the delivery of the pump; manually closed overpressure control valve connects the branch conduit downstream of the corresponding throttle to a tank and a normally open one-way valve connects the output conduit to the branch conduit downstream of the throttles and interrupts the connection as long as the overpressure control valve is open.

Abstract: The control system has an adjustable flow-rate pump and a fixed flow-rate pump which is supplied with hydraulic fluid via a supply conduit. A first throttle is interposed in this conduit and produces first signals in form of pressure differentials in dependence upon variations in the rotational speed of an ungoverned combustion engine which powers the hydraulic drive, which signals trigger flow-rate adjustments of the main pump. A second throttle is also interposed in the supply conduit and produces second signals in form of pressure differentials in dependence upon variations in the load upon the hydraulic motor of the hydraulic drive, which signals trigger movements of the throttle flap of the internal combustion engine towards the open or closed position thereof.

Abstract: An arrangement for controlling the operation of a fluid-displacement machine, such as a hydraulic pump or motor, which is equipped with an adjuster that adjusts the machine toward higher and lower throughputs in dependence upon the pressure of a control fluid acting thereon, includes a control valve which communicates the adjuster either with a high-pressure zone or with a low-pressure zone of a control circuit in different ones of its terminal positions. In addition thereto, the arrangement includes a pressure-limiting valve interposed between the low-pressure and the high-pressure zones of the control circuit. Both the control and pressure limiting valves are acted upon by the control fluid, the pressure of which is controlled by a common regulating valve.

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: The control system for a hydraulic transmission comprises a throttle element which consists of a constant throttle and a spring charged adjustable throttle arranged in parallel or, alternatively, comprises a combination of a constant throttle with adjustable throttles. The adjustable throttle has a cross section varying in response to the operating pressure of the hydrostatic transmission. The moment of rotation of a hydrometer included in the transmission is determined by the fluid stream caused by an adjustable pump which is adjusted by a servomechanism controlled by the throttle element and thus forms a transmission control member.

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: 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: A radial piston machine, such as a pump or a motor, has a housing in which a cylinder body is rotatable. The cylinder body has radial cylinder bores which accommodate reciprocable pistons. A shaft mounts the cylinder body for rotation and is formed with two axially spaced circumferential grooves between which it is also formed with a high-pressure control opening and with a diametrically opposite low-pressure control opening; these openings communicate intermittently with the inner ends of the cylinder bores. Sealing lands are formed on the shaft intermediate the grooves and the openings, and supporting lands are formed axially outwardly of the grooves.

Abstract: The transmission drives a dispensing apparatus at a speed varying in proportion to a command value furnished by a command device. The transmission includes a hydromotor driving the dispensing apparatus, a main pump driving the hydromotor, and a regulating arrangement for making the variations in the speed of the hydromotor proportional to the variations in the command value. The regulating arrangement includes first and second measuring pumps driven by the hydromotor and by the command device for generating control pressures respectively indicative of the hydromotor speed and the command value. The regulating arrangement further includes a hydraulic control device connected to receive the control pressures and operative for automatically varying the fluid output of the main pump in dependence upon the difference in the control pressures.

Abstract: A pressure regulator for an adjustable pump has an adjustable member for regulating the amount of fluid delivered by the pump. The position of the adjustable member is adjusted by two pistons of different diameters acting from opposite sides of the adjustable member and in which pressure of the fluid delivered by the pump is directed through a passage controlled by a control valve to one of the cylinder bores in which one of the pistons is closely guided. The control valve is movable by the fluid pressure between a neutral position in which fluid from the pump is prevented from flowing into the cylinder bore of the one piston, and two working positions, in one of which fluid from the pump will flow to the cylinder bore of the one piston while part of the fluid will flow over a throttle to a space at atmospheric pressure, and in the other of which fluid will flow unthrottled from the cylinder bore of the one piston to the aforementioned space.

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.