Abstract: The invention relates to a neutral setting apparatus for adjustable hydraulic machines, in particular the adjustment of the neutral position of a servo valve. In particular, the invention relates to servo adjustment devices with mechanically adjustable control pistons, wherein the forces necessary for this can be applied mechanically, electro-magnetically, pneumatically or hydraulically. The invention relates to a neutral setting apparatus of an adjustable hydraulic machine, with a housing in which a mounted input shaft is arranged, to one end of which a torque can be applied for rotating the input shaft about an axis. Thus providing a robust and cost-effective setting mechanism for the neutral position of a servo valve.

Abstract: The invention concerns a hydrostatic drive with a closed hydraulic fluid circuit comprising a hydraulic motor and a variable displacement pump. A feed pump feeds hydraulic fluid under pressure. A control device regulates pressure to a double-sided servo control unit comprising a control piston in a double-sided control cylinder so that the control piston can open a feed line for hydraulic fluid to one side while opening a discharge line on the other. The control device comprises an actuator at the cylinder by means of which force can be exerted onto the piston. A preload element exerts force onto the piston. The pressure generated by the variable displacement pump returns via a return line such that force is exerted in the direction of the piston, if inactive, the piston is maintained by the preload element and the pressure of the variable displacement pump.

Abstract: The invention relates to a neutral setting apparatus for adjustable hydraulic machines, in particular the adjustment of the neutral position of a servo valve. In particular, the invention relates to servo adjustment devices with mechanically adjustable control pistons, wherein the forces necessary for this can be applied mechanically, electro-magnetically, pneumatically or hydraulically. The invention relates to a neutral setting apparatus of an adjustable hydraulic machine, with a housing in which a mounted input shaft is arranged, to one end of which a torque can be applied for rotating the input shaft about an axis. Thus providing a robust and cost-effective setting mechanism for the neutral position of a servo valve.

Abstract: The invention relates to an axial piston engine with a filling pump integrated in a receiving bore of the axial piston engine, which filling pump comprises a gerotor set with an externally toothed inner ring and an internally toothed outer ring and also an inner thrust plate and an outer thrust plate. The two thrust plates enclose the gerotor set between them and, on their surfaces facing away from the gerotor set, are in each case supported via a pressure field seal, which surrounds the pressure field regions formed in the thrust plates, in such a way on the housing walls axially enclosing the filling pump that lateral play in the form of axial mobility of the filling pump is guaranteed.

Abstract: An arrangement for filtering a hydraulic fluid having a bypass line connecting the feed channel to the discharge channel where the bypass line is opened by a pressure switching valve when a pressure change is caused by the contamination of the filter element.

Abstract: A hydrostatic variable displacement unit is provided having a swash plate which serves to adjust the stroke of displacement pistons in a cylinder block and can be pivoted in its angular position by means of a servo system, the servo system having at least one servo piston with two servo-piston end surfaces which are in each case assigned a servo cylinder and a servo-piston rear surface, and the servo cylinders, by means of the assigned servo-piston end surfaces, in each case bounding a servo-cylinder pressure space. The servo piston is acted upon by a spring arrangement having at least one spring arranged outside the servo-cylinder pressure space and clamped between two spring plates. The two spring plates are acted upon by the springs in the direction of a stop of the particular servo cylinder that is situated on its side such that in the neutral position, the spring plates bear against the servo-piston rear surfaces and against the stop of the particular servo cylinder.

Abstract: The invention relates to a hydrostatic variable unit with a servo system bringing about the control of the hydrostatic unit and with a valve unit controlling the servo system, the valve unit comprising two magnetically actuated proportional pressure-reducing valves which respectively act upon one of the sides of a servo system, which sides operate counter to each other, and having a safety function which, in the event of an incident, transfers the servo system into a safety position. The safety function is realized by at least one of the proportional pressure-reducing valves being designed at the same time as a pilot valve for activating and deactivating the second proportional pressure-reducing valve.

Abstract: Elastically deformable seal of an electrical control unit of a hydraulic machine. The seal has a pot-like shape with a diaphragm, which is in the form of a pot base, and also pot inner faces, pot edge faces and pot outer faces. In this case, the pot inner faces have first sealing faces, the pot edge faces have abutment faces and the pot outer faces have second sealing faces. The first sealing faces and the abutment faces are formed in such a way that they deform under pressure loading such that the second sealing faces arch out from the pot outer faces.

Abstract: An axial piston machine having a swashplate or an oblique axis which can be adjusted by means of servopistons and has a valve segment and an adjustment unit for the electrically proportional adjustment of the volumetric displacement. The adjustment unit comprises proportional magnets which can be activated electrically, and a control piston for controlling the oil pressure which moves the servopistons. The proportional magnets act on the control piston along a common tappet axis, a feedback device for feeding back the current swashplate or oblique-axis valve-segment position to the control piston being provided. The feedback device comprises spring levers 6, 6? which can pivot about an axis, the spring levers 6, 6? each being mounted on the pivot axis 5 with a bearing shell 15, which are each composed of two component shells which support the spring lever 6, 6? at separate locations on the pivot axis 5, and which each essentially enclose a half-space about the pivot axis 5.

Abstract: The invention relates to a circuit for enabling or disabling hydraulic actuating devices, in particular for enabling the braking system of a hydraulic propel drive, having a device for checking the pressure level in working lines or control lines of hydraulic circuits, a maximum or minimum pressure level being checked in two or more working lines or control lines. An ‘OR’ logic circuit is provided for checking the pressures. In said ‘OR’ logic circuit, two or more pistons are arranged in series in a common bore. In each case one of the pressures to be checked is introduced into one of the spaces between the pistons and the space between one of the pistons and the base of the bore.

Abstract: The invention relates to a circuit for enabling or disabling a braking system of a hydraulic propel drive, having a device for checking operating parameters which are relevant to a neutral setting and having a spring device, in particular a load spring, which acts counter to the control piston of an electrohydraulic solenoid valve which is designed to enable the braking system by means of electrical operation. A device for generating a force, which is dependent on the neutral position, of the spring device is provided, wherein when a neutral setting is not present, the force action of the spring arrangement prevents the electrohydraulic solenoid valve from enabling the braking system, by acting counter to the electrical operation of the magnet of said solenoid valve.

Abstract: A valve arrangement in a hydraulic circuit comprises a longitudinal duct 3 and a transverse duct 2. A throttle slide 10 can be displaced in the direction of the longitudinal duct 3. Arranged in the throttle slide 10 is a valve piston 25, by means of which the flow through the hollow throttle slide 10 can be enabled or blocked. The flow of hydraulic fluid takes place through two groups of passage holes 33a, 35a, which are arranged in the throttle slide 10. The interaction of pressure and flow direction of the hydraulic fluid, and also the restoring force of a slide spring 20 and a piston spring 30, achieves a situation where hydraulic fluid can flow through the valve arrangement in both directions but that a throttling action occurs only when the hydraulic fluid flows from the transfer duct 2 to the longitudinal duct 3 under increased pressure.

Abstract: In the housing 1 of a hydraulic machine, the pressure Pi acts in the chamber 2. For this purpose, a passage opening 4 is provided, which is formed as a valve seat 5. A valve body 6 can be displaced longitudinally in the housing 1 and forms a pressure-tight spring chamber for an inner valve spring 21. The spring chamber is connected to the chamber 2 via a pressure equalizing hole 9. The prestress of the inner valve spring 21 can be set by means of a setting screw 18. In addition, there is an outer valve spring 22. Both the valve springs load the valve body 6 with the effect of closing it. The pressure equalizing valve described combines a compact design with an advantageous flow characteristic. When a maximum value of p1 is reached, the valve body 6 lifts off the valve seat 5 and hydraulic fluid from the chamber 2 flows away via the valve chamber 3.

Abstract: In the stationary part (1) of an axial piston machine, a first flow duct (2) and second flow duct (5) intersect with the central axes (3) and (6). A valve body (20) having a valve cone (21) and a tubular guide piston which can be displaced in relation to the valve cone is situated in the extension of the central axis (3) of the first flow duct (2). The valve body (21) bears against a first valve seat (4) which is surrounded by an expanded section (7). The entire valve body (20) moves in a tubular partial housing (9) which is connected to the stationary part (1) in a sealed manner via a seal (11), a screw connection (10) and a flange (12) which rests on a shoulder (13) of the stationary part (1). A first compression spring (27) and a second compression spring (28) serve to support the valve body (20) and its parts in relation to one another. An extension stem (22) passes through the tubular guide piston and guides the second compression spring (28).

Abstract: Arranged in a hydraulic circuit is a valve with an L-shaped duct arrangement, which is formed by a transverse duct 2 and a longitudinal duct 3. Formed in extension of the longitudinal duct 3 is a holding and guiding bore 4, in which a throttling element, comprising a throttle slide 10 and a valve piston 21 that can be displaced therein, can be displaced longitudinally. The valve piston 21 has a passage hole 25, which is connected to the interior of the throttling element and two proportionate annular chambers 17a and 17b. Of these, the proportionate annular chamber 17b is connected to a pilot control valve via a control duct 19. Depending on the direction and pressure of the hydraulic fluid flowing through the L-shaped duct arrangement, the throttling element is moved in or out and extended or compressed in the process.

Abstract: An axial piston machine having a swash plate or oblique axis which can be adjusted by means of servopistons and has a valve segment and an adjustment unit for the electrically proportional adjustment of the volumetric displacement, the adjustment unit comprising proportional magnets which can be activated electrically, and a control piston for controlling the oil pressure which moves the servopistons, the proportional magnets acting on this control piston along a common tappet axis. A feedback device for feeding back the current swash plate or oblique axis valve segment position is provided. The feedback device comprises spring levers and a pointer which can be pivoted about an axis, the pointer which is embodied as a two-armed lever engaging in the control piston on one side of the pivot axis, and between the spring levers on the other side.

Abstract: The invention relates to an axial piston engine with a filling pump integrated in a receiving bore of the axial piston engine, which filling pump comprises a gerotor set with an externally toothed inner ring and an internally toothed outer ring and also an inner thrust plate and an outer thrust plate. The two thrust plates enclose the gerotor set between them and, on their surfaces facing away from the gerotor set, are in each case supported via a pressure field seal, which surrounds the pressure field regions formed in the thrust plates, in such a way on the housing walls axially enclosing the filling pump that lateral play in the form of axial mobility of the filling pump is guaranteed.

Abstract: An axial piston machine having a swashplate or an oblique axis which can be adjusted by means of servopistons and has a valve segment and an adjustment unit for the electrically proportional adjustment of the volumetric displacement. The adjustment unit comprises proportional magnets which can be activated electrically, and a control piston for controlling the oil pressure which moves the servopistons. The proportional magnets act on the control piston along a common tappet axis, a feedback device for feeding back the current swashplate or oblique-axis valve-segment position to the control piston being provided. The feedback device comprises spring levers 6, 6? which can pivot about an axis, the spring levers 6, 6? each being mounted on the pivot axis 5 with a bearing shell 15, which are each composed of two component shells which support the spring lever 6, 6? at separate locations on the pivot axis 5, and which each essentially enclose a half-space about the pivot axis 5.

Abstract: An axial piston machine having a swash plate or oblique axis which can be adjusted by means of servopistons and has a valve segment and an adjustment unit for the electrically proportional adjustment of the volumetric displacement, the adjustment unit comprising proportional magnets which can be activated electrically, and a control piston for controlling the oil pressure which moves the servopistons, the proportional magnets acting on this control piston along a common tappet axis. A feedback device for feeding back the current swash plate or oblique axis valve segment position is provided. The feedback device comprises spring levers and a pointer which can be pivoted about an axis, the pointer which is embodied as a two-armed lever engaging in the control piston on one side of the pivot axis, and between the spring levers on the other side.

Abstract: A valve arrangement in a hydraulic circuit comprises a longitudinal duct 3 and a transverse duct 2. A throttle slide 10 can be displaced in the direction of the longitudinal duct 3. Arranged in the throttle slide 10 is a valve piston 25, by means of which the flow through the hollow throttle slide 10 can be enabled or blocked. The flow of hydraulic fluid takes place through two groups of passage holes 33a, 35a, which are arranged in the throttle slide 10. The interaction of pressure and flow direction of the hydraulic fluid, and also the restoring force of a slide spring 20 and a piston spring 30, achieves a situation where hydraulic fluid can flow through the valve arrangement in both directions but that a throttling action occurs only when the hydraulic fluid flows from the transfer duct 2 to the longitudinal duct 3 under increased pressure.