Abstract: Manual displacement control device (MDC) for hydraulic units has an input shaft mounted rotatably about an input shaft axis in an input shaft block. The input shaft protrudes from the input shaft block with a first end, onto which a rotating torque can be applied. The MDC further includes a control spool housed in a control housing, which is moveable by means of rotating the input shaft for controlling a servo pressure. The control device has positioning means for adjusting and fixing the lateral position of the input shaft with respect to the control housing in a direction perpendicular to the input shaft axis and perpendicular to the direction of a restoring force exerted on the input shaft. The hydraulic unit is adjustable to its neutral position by means of a servo spring bracket providing an end stop surface for a servo spring seat towards the displacement element.

Abstract: The invention relates to a high-pressure hydraulic fluid screening element (1) for inserting into a hydraulic line or into a hydraulic connection of a hydraulic device, having an annular main body (2), which is aligned with respect to its axis of rotation (9) in a longitudinal direction (5). The outside diameter of the main body (2) is greater than its axial length. The inner cross section of the main body (2) is covered over by a screening region (3), which is provided with a multiplicity of apertures (4). In this case, the main body (2) and the screening region (3) are produced integrally by the powder injection-molding process.

Abstract: Manual displacement control device (MDC) for hydraulic units has an input shaft mounted rotatably about an input shaft axis in an input shaft block. The input shaft protrudes from the input shaft block with a first end, onto which a rotating torque can be applied. The MDC further includes a control spool housed in a control housing, which is moveable by means of rotating the input shaft for controlling a servo pressure. The control device has positioning means for adjusting and fixing the lateral position of the input shaft with respect to the control housing in a direction perpendicular to the input shaft axis and perpendicular to the direction of a restoring force exerted on the input shaft. The hydraulic unit is adjustable to its neutral position by means of a servo spring bracket providing an end stop surface for a servo spring seat towards the displacement element.

Abstract: Displacement control device for providing pressure fluid to a servo unit for adjusting the displacement of a pressure fluid unit, having a control cylinder in which a control spool is mounted shiftable along the longitudinal axis of the control cylinder, an inlet port, a servo port and a discharge port are formed in the control cylinder longitudinally spaced from each other, wherein the control spool comprising: a basically cylindrical outer surface; a front face on which an actuation force can act for shifting the control spool along the longitudinal axis; a discharge area opposite to the front face; a longitudinal bore inside the control spool, wherein one end of the longitudinal bore opens towards the front face and the other end is connected via a backpressure orifice with the discharge area; a control recess provided lengthwise in the outer surface; a radial bore which connects via a flow limiting orifice the longitudinal bore with the outer surface, wherein the opening of the radial bore at the outer su

Abstract: Displacement control device for providing pressure fluid to a servo unit for adjusting the displacement of a pressure fluid unit, having a control cylinder in which a control spool is mounted shiftable along the longitudinal axis of the control cylinder, an inlet port, a servo port and a discharge port are formed in the control cylinder longitudinally spaced from each other, wherein the control spool comprising: a basically cylindrical outer surface; a front face on which an actuation force can act for shifting the control spool along the longitudinal axis; a discharge area opposite to the front face; a longitudinal bore inside the control spool, wherein one end of the longitudinal bore opens towards the front face and the other end is connected via a backpressure orifice with the discharge area; a control recess provided lengthwise in the outer surface; a radial bore which connects via a flow limiting orifice the longitudinal bore with the outer surface, wherein the opening of the radial bore at the outer su

Abstract: Pressure relief valve (1) comprising a valve housing (2), in which a double-side operable cylindrical pressure relief valve spool (3) is housed slidable along a longitudinal axis (4) of a cylindrical bore (5) in the valve housing (2). The pressure relief valve spool (3) can be shifted into a first position by a first force acting on an actuating side (6) of the pressure relief valve spool (3) and can be shifted into a second position by a pressure force acting on a sealing side (7) of the pressure relief valve spool (3). On the sealing side (7) of the pressure relief valve spool (3) a double-sealing, rotational symmetric poppet (30) is located having a rotational axis (34), a first convex sealing surface (31) and a second convex sealing surface (32). The first sealing surface (31) facing away from the pressure relief valve spool (3) is provided for sealing with an external valve seat (11).

Abstract: A Control unit of a hydraulic unit comprises a control piston slidable arranged in a control cylinder to provide a hydraulic fluid under servo pressure at a first outlet of the control unit suitable for the displacement of the hydraulic unit. The servo pressure is proportional to a sum of the inner forces of the hydraulic unit and the operational forces act on the control unit. The hydraulic fluid provided at the outlet is fed by a charge pressure supply at charge pressure at an inlet of the control unit. The control piston has a blind bore in the direction of a longitudinal axis of the control unit, in which a pressure relief valve is arranged functioning as a pilot-control unit having a two-sided pressure relief piston arranged in the blind bore and slidable relative to the control piston by means of an actuator.

Abstract: The invention relates to a high-pressure hydraulic fluid screening element (1) for inserting into a hydraulic line or into a hydraulic connection of a hydraulic device, having an annular main body (2), which is aligned with respect to its axis of rotation (9) in a longitudinal direction (5). The outside diameter of the main body (2) is greater than its axial length. The inner cross section of the main body (2) is covered over by a screening region (3), which is provided with a multiplicity of apertures (4). In this case, the main body (2) and the screening region (3) are produced integrally by the powder injection-molding process.

Abstract: The invention relates to a displacement unit (1) of a hydraulic machine, for which the hysteresis is reduced. For this purpose, in the control spool (3) and/or at the control spool (3) a mass body (16) and a spring (17) are arranged, which are excited to resonance vibrations. The vibrations are self-excited and sustained by a partial flow rate of the hydraulic fluid which is modulated periodically. The high frequent vibrations are transmitted over the spring (17) onto the associated control spool (3), thereby reducing the friction and hence the hysteresis.

Abstract: The invention relates to a high-pressure hydraulic fluid screening element (1) for inserting into a hydraulic line or into a hydraulic connection of a hydraulic device, having an annular main body (2), which is aligned with respect to its axis of rotation (9) in a longitudinal direction (5). The outside diameter of the main body (2) is greater than its axial length. The inner cross section of the main body (2) is covered over by a screening region (3), which is provided with a multiplicity of apertures (4). In this case, the main body (2) and the screening region (3) are produced integrally by the powder injection-molding process.

Abstract: Method for deceleration of a hydrostatic transmission 3 driven by a drive motor 2 comprising a closed hydraulic fluid circuit, in which a hydraulic pump 4 coupled mechanically with the drive motor 2 and a hydraulic motor 5 are arranged. Two hydraulic lines 6, 7 connect the hydraulic pump 4 and the hydraulic motor 5 and constitute for the hydraulic motor 5 according to the drive direction of the hydrostatic transmission 3 a supply line 6 and a return line 7.

Abstract: Pressure relief valve (1) comprising a valve housing (2), in which a double-side operable cylindrical pressure relief valve spool (3) is housed slidable along a longitudinal axis (4) of a cylindrical bore (5) in the valve housing (2). The pressure relief valve spool (3) can be shifted into a first position by a first force acting on an actuating side (6) of the pressure relief valve spool (3) and can be shifted into a second position by a pressure force acting on a sealing side (7) of the pressure relief valve spool (3). On the sealing side (7) of the pressure relief valve spool (3) a double-sealing, rotational symmetric poppet (30) is located having a rotational axis (34), a first convex sealing surface (31) and a second convex sealing surface (32). The first sealing surface (31) facing away from the pressure relief valve spool (3) is provided for sealing with an external valve seat (11).

Abstract: Hydrostatic adjusting device of a hydraulic machine, the swept volume of which can be adjusted by way of a servo adjusting unit, having a control unit which has a control cylinder which has at least one inlet for pressurized hydraulic fluid, at least one servo connector for a connecting line to the servo adjusting unit, and at least one outlet to a hydraulic fluid collecting region. A control piston is arranged in the control cylinder, which control piston can be displaced by means of at least one control piston actuator and has control edges. In interaction with control edges which are configured in the control cylinder, the inlet or the outlet can be alternately connected hydraulically to the connecting line, whereby the pressure which prevails in the connecting line can be returned hydraulically via a control line to at least one end side of the control piston.

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 displacement unit (1) of a hydraulic machine, for which the hysteresis is reduced. For this purpose, in the control spool (3) and/or at the control spool (3) a mass body (16) and a spring (17) are arranged, which are excited to resonance vibrations. The vibrations are self-excited and sustained by a partial flow rate of the hydraulic fluid which is modulated periodically. The high frequent vibrations are transmitted over the spring (17) onto the associated control spool (3), thereby reducing the friction and hence the hysteresis.

Abstract: The invention relates to a displacement unit (1) of a hydraulic machine, for which the hysteresis is reduced. For this purpose, in the control spool (3) and/or at the control spool (3) a mass body (16) and a spring (17) are arranged, which are excited to resonance vibrations. The vibrations are self-excited and sustained by a partial flow rate of the hydraulic fluid which is modulated periodically. The high frequent vibrations are transmitted over the spring (17) onto the associated control spool (3), thereby reducing the friction and hence the hysteresis.

Abstract: A Control unit (2) of a hydraulic unit comprises a control piston (3) slidable arranged in a control cylinder (4) to provide a hydraulic fluid under servo pressure (P2) at a first outlet (8) of the control unit (2) suitable for the displacement of the hydraulic unit. The servo pressure (P2) is proportional to a sum of the inner forces of the hydraulic unit and the operational forces act on the control unit (2). The hydraulic fluid provided at the outlet (8) is fed by a charge pressure supply at charge pressure (P1) at an inlet (7) of the control unit (2).

Abstract: Method for deceleration of a hydrostatic transmission 3 driven by a drive motor 2 comprising a closed hydraulic fluid circuit, in which a hydraulic pump 4 coupled mechanically with the drive motor 2 and a hydraulic motor 5 are arranged. Two hydraulic lines 6, 7 connect the hydraulic pump 4 and the hydraulic motor 5 and constitute for the hydraulic motor 5 according to the drive direction of the hydrostatic transmission 3 a supply line 6 and a return line 7.

Abstract: The invention relates to a high-pressure hydraulic fluid screening element (1) for inserting into a hydraulic line or into a hydraulic connection of a hydraulic device, having an annular main body (2), which is aligned with respect to its axis of rotation (9) in a longitudinal direction (5). The outside diameter of the main body (2) is greater than its axial length. The inner cross section of the main body (2) is covered over by a screening region (3), which is provided with a multiplicity of apertures (4). In this case, the main body (2) and the screening region (3) are produced integrally by the powder injection-moulding process.

Abstract: Hydrostatic adjusting device of a hydraulic machine, the swept volume of which can be adjusted by way of a servo adjusting unit, having a control unit which has a control cylinder which has at least one inlet for pressurized hydraulic fluid, at least one servo connector for a connecting line to the servo adjusting unit, and at least one outlet to a hydraulic fluid collecting region. A control piston is arranged in the control cylinder, which control piston can be displaced by means of at least one control piston actuator and has control edges. In interaction with control edges which are configured in the control cylinder, the inlet or the outlet can be alternately connected hydraulically to the connecting line, whereby the pressure which prevails in the connecting line can be returned hydraulically via a control line to at least one end side of the control piston.