Hydrostatic axial piston machine

Abstract

A hydrostatic axial piston machine (1), in particular an axial piston pump, with an adjustable displacement volume, which is operated in a closed circuit, wherein the displacement volume is adjustable by means of an actuating device (4), wherein the actuating device (4) comprises a pressure-cutting function (16) which has a pressure-cutting valve (15) which is actuated depending on the pressure at a first pressure port (A) of the axial piston machine (1) and depending on the pressure at a second pressure port (B) of the axial piston machine (1). The pressure-cutting valve (15) is operatively connected to a first actuating piston (35a) which is actuated by the pressure at the first pressure port (A), and to a second actuating piston (35b) which is actuated by the pressure at the second pressure port (B).

Description

[0001] The invention relates to a hydrostatic axial piston machine, in particular an axial piston pump, with adjustable displacement volume, which is operated in a closed circuit, wherein the displacement volume is adjustable by means of an adjusting device, wherein the adjusting device includes a pressure cutting function which has a pressure cutting valve which is actuated depending on the pressure at a first pressure port of the axial piston machine and depending on the pressure at a second pressure port of the axial piston machine.

[0002] Such hydrostatic axial piston machines with variable displacement volume, operating in a closed circuit, are used as pumps or motors, for example, in the drive systems of mobile machinery or in the slewing drives of excavators. The actuator allows the displacement volume of the axial piston machine to be changed. Due to the pressure-cutting function of the actuator, in the case of an axial piston pump designed as an axial piston machine, during the acceleration phase, when a maximum high pressure is reached at the first or second pressure port, the axial piston pump is adjusted towards a reduction in displacement volume, thereby preventing the activation of an overpressure protection device in the closed circuit, such as a pressure relief valve.This prevents pressure medium from escaping the circuit via the overpressure protection device, thus preventing power losses and unnecessary heating of the pressure medium.

[0003] From DE 103 51 930 A1, a hydrostatic axial piston machine is known in which the pressure-cutting function is formed by two pilot valves designed as pressure-limiting valves, each assigned to a pressure port of the axial piston machine. Such a pressure-cutting function is complex due to the two pressure-limiting valves.

[0004] From DE 34 02 634 A1, a hydrostatic axial piston machine of this type is known, in which the pressure-cutting function comprises a single pressure-cutting valve. In order to selectively apply and thus actuate the pressure-cutting valve from either the pressure at a first pressure port of the axial piston machine or from the pressure at a second pressure port of the axial piston machine, DE 34 02 634 A1 provides a changeover valve acting as a switching valve. This valve is connected at a first inlet to the first pressure port of the axial piston machine, at a second inlet to the second pressure port of the axial piston machine, and at an outlet to the pressure-cutting valve for its control and actuation.However, such a changeover valve causes a high construction effort, since such a changeover valve has many gaps that must be sealed against the high pressure present at the two pressure ports of the axial piston machine, which can be more than 400 bar in known axial piston machines, and these gaps must be manufactured with high precision.

[0005] The present invention is based on the objective of providing a hydrostatic axial piston machine of the type mentioned above, in which the construction effort for the pressure cutting function is reduced.

[0006] This problem is solved according to the invention by the pressure cutting valve being operatively connected to a first actuating piston, which is acted upon by the pressure at the first pressure port, and to a second actuating piston, which is acted upon by the pressure at the second pressure port.

[0007] In the axial machine according to the invention, the pressure-cutting function is formed by a single pressure-cutting valve, which is operatively connected to the first actuating piston, which is actuated by the pressure at the first pressure port, and to the second actuating piston, which is actuated by the pressure at the second pressure port. Thus, the two actuating pistons enable the pressure-cutting valve to be selectively actuated by either the pressure at the first pressure port or the pressure at the second pressure port of the axial piston machine, without the need for a complex changeover valve.Such a pressure-cutting function, which has a single pressure-cutting valve and two actuating pistons for selecting the high pressure present at the corresponding pressure port of the axial piston machine for actuating the pressure-cutting valve, has low manufacturing effort and therefore low production costs.

[0008] According to an advantageous embodiment of the invention, the pressure-cutting valve is connected at a first port to a control pressure supply device, at a second port to the actuating device, and at a third port to a container, wherein the pressure-cutting valve has a first control position in which the first port is connected to the second port and the third port is closed, and a second control position in which the second port is connected to the third port and the first port is closed, wherein the pressure-cutting valve is acted upon by a spring device in the direction of the first control position and is acted upon by the first actuating piston and by the second actuating piston in the direction of the second control position.

[0009] According to an advantageous embodiment of the invention, the pressure-cutting valve has a control slide arranged longitudinally displaceable in a housing bore of a valve sleeve.

[0010] According to an advantageous embodiment of the invention, the first actuating piston and the second actuating piston are arranged to be longitudinally displaceable in a housing bore of a further valve sleeve, wherein the further valve sleeve is detachably attached to the valve sleeve.By using one valve sleeve for the control slide of the pressure-cutting valve and another valve sleeve for the two actuating pistons, the construction effort of the pressure-cutting function according to the invention can be further simplified, since only the second valve sleeve needs to be designed and manufactured with corresponding precision for the high pressure in the range of 400 bar at the two pressure ports of the axial piston machine, whereas the valve sleeve of the control slide can be designed for significantly lower pressures in the range of a maximum of 50 bar, which makes it possible for only the second valve sleeve for the two actuating pistons to be heat-treated and for the valve sleeve of the control slide of the pressure-cutting valve to be manufactured in a cost-effective manner without heat treatment.

[0011] According to an advantageous embodiment of the invention, the housing bore of the valve sleeve and the housing bore of the further valve sleeve are arranged in axial alignment. This results in an axially aligned arrangement of the control spool of the pressure-cutting valve and the two actuating pistons, thereby enabling trouble-free and reliable actuation of the control spool of the pressure-cutting valve by the actuating pistons.

[0012] According to an advantageous embodiment of the invention, the second actuating piston is arranged axially adjacent to the first actuating piston in the housing bore of the further valve sleeve. This results in a series arrangement of the two actuating pistons in the housing bore of the further valve sleeve, which allows for further simplifications in terms of construction effort.

[0013] According to an advantageous embodiment of the invention, the first actuating piston is arranged with a first end face adjacent to an end face of the control spool of the pressure-cutting valve, and a second end face of the first actuating piston, opposite the first end face, is subjected to the pressure at the first pressure port. This allows for simple actuation of the control spool of the pressure-cutting valve by the first actuating piston when a corresponding pressure is present at the first pressure port of the axial piston machine on its second end face.

[0014] According to an advantageous embodiment of the invention, the second actuating piston is arranged with a first end face adjacent to the second end face of the first actuating piston, and a second end face of the second actuating piston, opposite the first end face, is subjected to the pressure at the second pressure port. This allows for simple actuation of the control spool of the pressure-cutting valve by the second actuating piston when a corresponding pressure is present at its second end face at the second pressure port of the axial piston machine. The first actuating piston, arranged axially between the control spool of the pressure-cutting valve and the second actuating piston, serves only to transmit the force generated by the pressure at the second pressure port on the second actuating piston to the control spool of the pressure-cutting valve for its actuation.

[0015] According to an advantageous embodiment of the invention, a first control port is formed on the housing bore of the further valve sleeve, which is connected to the first pressure port, and a second control port is formed, which is connected to the second pressure port, wherein the second control port is arranged axially spaced from the first control port in the longitudinal direction of the further valve sleeve. This allows the first actuating piston to be actuated by the pressure at the first pressure port of the axial piston machine and the second actuating piston to be actuated by the pressure at the second pressure port of the axial piston machine in a simple manner.

[0016] According to an advantageous embodiment of the invention, the second end face of the first actuating piston is formed on a pin section of the first actuating piston with a reduced diameter. This ensures in a simple manner that, with the end faces of the actuating pistons in contact, the first actuating piston can be actuated by the pressure at the first pressure port of the axial piston machine in order to actuate the valve spool of the pressure-cutting valve.

[0017] According to an advantageous embodiment of the invention, the first end face of the second actuating piston is formed on a pin section of the second actuating piston that has a reduced diameter. This ensures in a simple manner that, when the end faces of the actuating pistons are in contact, the second actuating piston is separated from the pressure at the first pressure port of the axial piston machine from the pressure at the first actuating piston, so that the pressure present at the first pressure port of the axial piston machine can act on the second end face of the first actuating piston and actuate the first actuating piston to actuate the valve slide of the pressure-cutting valve.

[0018] The invention has a number of advantages.

[0019] The pressure-cutting valve according to the invention, which, instead of a selector valve designed as a changeover valve, has two actuating pistons arranged in series in order to selectively actuate the pressure-cutting valve either from the pressure at the first pressure port of the axial piston machine or from the pressure at the second pressure port of the axial piston machine, has few high-pressure-carrying components and few high-pressure-carrying gaps, namely the two actuating pistons and the further valve sleeve. In the pressure-cutting valve according to the invention, only the housing bore in the further valve sleeve, in which the two actuating pistons are arranged to be longitudinally displaceable, needs to be precisely manufactured in order to seal the high pressure acting on the actuating pistons. The further valve sleeve can be sealed on its outer circumference by means of suitable seals, for example, soft gaskets or steel sealing rings.By using the valve sleeve for the control spool of the pressure-cutting valve and the additional valve sleeve for the two actuating pistons, only the additional valve sleeve for the two actuating pistons, which forms the high-pressure section of the pressure-cutting valve, requires heat treatment, whereas the valve sleeve for the control spool of the pressure-cutting valve, which forms the low-pressure section of the pressure-cutting valve, can be manufactured without heat treatment. The additional valve sleeve can be detachably attached to the valve sleeve with minimal construction effort, for example, using a round wire snap ring.

[0020] Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiment shown in the schematic figures. Here, Figure 1 shows a circuit diagram of an axial piston machine according to the invention, Figure 2 shows the pressure cutting valve of the axial piston machine. Figure 1in a longitudinal section.

[0021] In the Figure 1 The circuit diagram of a hydrostatic drive machine 1 according to the invention is shown. In the illustrated embodiment, the hydrostatic drive machine 1 is designed as an axial piston pump that operates in a closed circuit.

[0022] An axial piston machine 1, designed as a hydrostatic axial piston pump, is driven by a drive motor (not shown in detail), for example, an internal combustion engine or an electric motor. The machine is connected in a closed circuit to at least one hydraulic consumer (not shown in detail), for example, a hydraulic motor of a drive system or a rotary drive. The closed circuit consists of a first pressure medium line 2a and a second pressure medium line 2b, wherein the first pressure medium line 2a is connected to a first pressure port A of the axial piston machine 1 and the second pressure medium line 2b is connected to a second pressure port B of the axial piston machine 1.

[0023] The axial piston machine 1 is designed as a variable displacement pump with adjustable displacement volume and has a delivery volume control device 3, for example a swashplate designed as a cradle, which is in operative connection with an control device 4 for adjustment.

[0024] The actuating device 4 has a spring-centered actuating piston 5 which is operatively connected to the delivery volume actuating device 3 and which is provided with a first control pressure chamber 5a and a second control pressure chamber 5b.

[0025] A position-controlled control valve 6 is provided for controlling the pressurization of the control pressure chambers 5a and 5b of the actuating piston 5. The control valve 6 has a control pressure port 7, which is connected to a control pressure line 8. The control valve 6 also has a first control pressure port 9a, which is connected to the first control pressure chamber 5a of the actuating piston 5 via a first control pressure line 10a. A second control pressure port 9b of the control valve 6 is connected to the second control pressure chamber 5b of the actuating piston 5 via a second control pressure line 10b. The control valve 6 also has reservoir ports 11a and 11b, which are connected to a reservoir line 12 leading to a reservoir 13. The actuating piston 5, and thus the delivery volume control device 3, is operatively connected to the control valve 6 for position control via a mechanical linkage 14.

[0026] The actuating device 4 further includes a pressure cutting function 16, which has a pressure cutting valve 15 that is selectively actuated by the pressure at the first pressure port A of the axial piston machine 1 and by the pressure at the second pressure port B of the axial piston machine 1.

[0027] The pressure cutting valve 15 is connected at a first port A1 to a control pressure supply device 20, for example a control pressure pump 21. A delivery line 22 of the control pressure supply device 20 is connected to port A1 for this purpose.

[0028] At a second connection A2, the pressure cutting valve 15 is connected to the control pressure line 8 which leads to the control valve 6.

[0029] The pressure-cutting valve 15 is connected to the container 13 at a third port A3. A container line 23 leading to the container 13 is connected to this third port A3.

[0030] The pressure-cutting valve 15 has a first control position 15a, in which the first port A1 is connected to the second port A2 and the third port A3 is closed, and a second control position 15b, in which the second port A2 is connected to the third port A3 and the first port A1 is closed. An intermediate position 15c is provided between control positions 15a and 15b, in which ports A1, A2, and A3 are connected to each other.

[0031] The pressure cutting valve 15 is acted upon by a spring device 30 in the direction of the first control position 15a.

[0032] The pressure-cutting valve 15 is actuated in the direction of the second control position 15b by a first actuating piston 35a, which is in operative connection with the pressure-cutting valve 15 and is actuated by the pressure at the first pressure port A of the axial piston machine 1, and by a second actuating piston 35b, which is in operative connection with the pressure-cutting valve 15 and is actuated by the pressure at the second pressure port B of the axial piston machine 1.

[0033] A control line 36a, connected to the first pressure medium line 2a, is routed to the first actuating piston 35a. A corresponding control line 36b, connected to the second pressure medium line 2b, is routed to the second actuating piston 35b.

[0034] If the force generated at the first actuating piston 35a from the force of the pressure at the first port A exceeds the preload of the spring device 30, the pressure cutting valve 15 is actuated in the direction of the second control position 15b, in which the actuating pressure present in the control pressure line 8 led to the control valve 6 is reduced to the container 13, thereby adjusting the delivery volume control device 3 in the direction of a reduction of the displacement volume.

[0035] If the force generated at the second actuating piston 35b from the force of the pressure at the second port B exceeds the preload of the spring device 30, the pressure cutting valve 15 is actuated in the direction of the second control position 15b, in which the actuating pressure present in the control pressure line 8 led to the control valve 6 is reduced to the container 13, thereby adjusting the delivery volume control device 3 in the direction of a reduction of the displacement volume.

[0036] In the Figure 2 is a longitudinal section of the pressure cutting valve 15 of the Figure 1 shown with the two actuating pistons 35a, 35b.

[0037] The pressure-cutting valve 15 has a valve sleeve 50 in which a housing bore 51, designed as a longitudinal bore, is formed, in which a control spool 52 of the pressure-cutting valve 15 is arranged to be longitudinally displaceable. The housing bore 51 is designed as a through-bore extending through the entire length of the valve sleeve 50.

[0038] A spring chamber is formed between the housing bore 51 and a locking screw 53, in which the spring assembly 30 is arranged. In the illustrated embodiment, the preload of the spring assembly 30 is adjustable by means of a threaded pin 54, which can be screwed into the locking screw 53.

[0039] The spring assembly 30 is operatively connected to the control slide 51 via an interposed spring plate 55. In control position 15a, the spring plate 55 rests against a shoulder 56 of the housing bore 51. In control position 15b, the spring plate 55 rests against a stop 57, which is formed, for example, by a snap ring fixed in the housing bore 51.

[0040] The valve sleeve 50 has connections A1, A2, A3, with connection A2 being arranged between connections A1, A3 in the longitudinal direction of the valve sleeve 50.

[0041] The control valve 52 is provided with a first control recess 58, which controls the connection of port A1 with port A2, and a second control recess 59, which controls the connection of port A2 with port A3.

[0042] The spring chamber is connected to the control recess 59 and thus to the connection A3 which is connected to the container 13 by means of a longitudinal bore 60 formed in the control slide 52 and a transverse bore 61 branching off from the longitudinal bore 60.

[0043] The first actuating piston 35a and the second actuating piston 35b are arranged to be longitudinally displaceable in a housing bore 65 of a further valve sleeve 66, which is designed as a longitudinal bore. The housing bore 65 is designed as a through bore extending through the further valve sleeve 66 over its entire length.

[0044] The further valve sleeve 66 is detachably attached to the valve sleeve 50. According to the Figure 2 The further valve sleeve 66, with a shoulder at the right end area of ​​the further valve sleeve 66, is inserted into the housing bore 51 of the valve sleeve 50 and secured in the axial direction by means of a locking device 67, for example a snap ring 68.

[0045] In the assembled state, the housing bore 51 of the valve sleeve 50 and the housing bore 65 of the further valve sleeve 66 are aligned and have a common longitudinal axis L.

[0046] The second actuating piston 35b is arranged axially adjacent to the first actuating piston 35a in the housing bore 65 of the further valve sleeve 66, so that the two actuating pistons 35a 35b are connected in series and arranged one behind the other in the housing bore 65.

[0047] The first actuating piston 35a is arranged - viewed in the longitudinal direction of the longitudinal axis L - between the control slide 52 and the second actuating piston 35b.

[0048] The first actuating piston 35a is equipped with a first, in which Figure 2 The right end face 70a is arranged adjacent to an end face 72 of the control slide 52 of the pressure-cutting valve 15. One of the end faces opposite the first end face 70a, in which Figure 2 The left, second end face 70b of the first actuating piston 35a is subjected to the pressure at the first pressure port A. A first control port S1 is provided on the further valve sleeve 66 for this purpose, which is connected to the control line 36a and thus to the first pressure port A.

[0049] The second actuating piston 35b is equipped with one in which Figure 2 The first end face 71a on the right is adjacent to the second end face 70b of the first actuating piston 35a. One of the end faces opposite the first end face 71a, in the Figure 2 The left, second end face 71b of the second actuating piston 35b is subjected to the pressure at the second pressure port B. A second control port S2 is provided on the further valve sleeve 66 for this purpose, which is connected to the control line 36b and thus to the second pressure port B.

[0050] The second control port S2 is axially spaced from the first control port S1 in the longitudinal direction L of the further valve sleeve 66. According to the Figure 2 The first control port S1 is arranged in the middle area of ​​the further valve sleeve 66 and the second control port S2 is formed in a left end area of ​​the further valve sleeve 66.

[0051] The left end of the housing bore 65 of the further valve sleeve 66 is closed by means of a sealing screw 75 screwed into the further valve sleeve 66.

[0052] The second end face 70b of the first actuating piston 35a is formed on a pin section of the first actuating piston 35a with a reduced diameter. An annular gap is formed between the pin section of the first actuating piston 35a and the housing bore 65, which is connected to the control port S1.

[0053] The first end face 71a of the second actuating piston 35b is formed on a pin section of the second actuating piston 35b with a reduced diameter. An annular gap is formed between the pin section of the second actuating piston 35b and the housing bore 65, which is connected to the control port S1.

[0054] The further valve sleeve 66 is provided on its outer circumference with annular grooves 81, 82, into which seals, for example soft seals or steel sealing rings, can be inserted, with which a seal of the high-pressure-carrying control ports S1, S2 can be achieved against a receiving bore (not shown in detail), into which the further valve sleeve 66 and the valve sleeve 50 can be installed.

[0055] For fastening in the receiving bore, a threaded section 80 is formed on the valve sleeve 50, by means of which the valve sleeve 50 can be screwed into the receiving bore. For sealing the valve sleeve 50 against the receiving bore, an annular groove 85 is formed on the outer circumference of the valve sleeve 50, into which a seal, for example an O-ring, can be inserted.

[0056] The axial piston machine 1 according to the invention operates as follows.

[0057] If, by appropriate control of the control valve 6, the delivery volume control device 3 is adjusted such that the axial piston machine 1 delivers at the first pressure port A and thus into the first pressure medium line 2a, the high pressure present at the first pressure port A is present in the control line 36a, which is connected to the control port S1. The pressure present at the control port S1 is present at the annular gaps formed by the pin sections of the actuating pistons 35a, 35b and the housing bore 65 and displaces the second actuating piston 35b in the Figure 2 to the left, so that the pressure of the first pressure port A at the control port S1 is applied to the second end face 70b of the first actuating piston 35a. As soon as the force on the second end face 70b of the first actuating piston 35a resulting from the pressure of the first pressure port A exceeds the preload of the spring assembly 30, the first actuating piston 35a is moved to the left. Figure 2 The control spool 52 of the pressure-cutting valve 15 is moved to the right and actuates it from the first control position 15a towards the second control position 15b. In the second control position 15b of the pressure-cutting valve 15, the pressure in the control pressure line 8 is reduced by the connection of ports A2 and A3, which adjusts the delivery volume control device 3 towards a reduction in the displacement volume of the axial piston pump and achieves pressure cut-off.

[0058] If, by appropriate control of the control valve 6, the delivery volume control device 3 is adjusted such that the axial piston machine 1 delivers at the second pressure port B and thus into the second pressure medium line 2b, the high pressure present at the second pressure port B is present in the control line 36b, which is connected to the control port S2, so that the pressure present at the control port S2 of the second pressure port B is present on the second end face 71b of the second actuating piston 35b. As soon as the force on the second end face 71b of the second actuating piston 35b resulting from the pressure of the second pressure port B exceeds the preload of the spring device 30, the second actuating piston 35b is moved to the Figure 2 shifted to the right, so that the second actuating piston 35b also moves the first actuating piston 35a in the Figure 2The first actuating piston 35a shifts the control spool 52 of the pressure-cutting valve 15 to the right, actuating it from the first control position 15a towards the second control position 15b. The first actuating piston 35a transmits the force generated at the second actuating piston 35b to the control spool 52 of the pressure-cutting valve 15. In the second control position 15b of the pressure-cutting valve 15, the connection of ports A2 and A3 reduces the pressure in the control pressure line 8, thereby adjusting the delivery volume control device 3 towards a reduction in the displacement volume of the axial piston pump and achieving pressure cut-off.

Claims

1. Hydrostatic axial piston machine (1), in particular an axial piston pump, with adjustable displacement volume, which is operated in a closed circuit, wherein the displacement volume is adjustable by means of an adjusting device (4), wherein the adjusting device (4) comprises a pressure cutting function (16) which has a pressure cutting valve (15) which is actuated depending on the pressure at a first pressure port (A) of the axial piston machine (1) and depending on the pressure at a second pressure port (B) of the axial piston machine (1), characterized by the fact that the pressure cutting valve (15) is operatively connected to a first actuating piston (35a) which is acted upon by the pressure at the first pressure port (A), and to a second actuating piston (35b) which is acted upon by the pressure at the second pressure port (B).

2. Hydrostatic axial piston machine (1) according to claim 1, characterized by the fact thatThe pressure-cutting valve (15) is connected at a first port (A1) to a control pressure supply device (20), at a second port (A2) to the actuating device (4), and at a third port (A3) to a reservoir (13), wherein the pressure-cutting valve (15) has a first control position (15a) in which the first port (A1) is connected to the second port (A2) and the third port (A3) is closed, and a second control position (15b) in which the second port (A2) is connected to the third port (A3) and the first port (A1) is closed, wherein the pressure-cutting valve (15) is acted upon by a spring device (30) in the direction of the first control position (15a) and is acted upon by the first actuating piston (35a) and by the second actuating piston (35b) in the direction of the second control position (15b).

3. Hydrostatic axial piston machine (1) according to claim 1 or 2, characterized by the fact that the pressure cutting valve (15) has a control slide (52) arranged longitudinally displaceable in a housing bore (51) of a valve sleeve (50).

4. Hydrostatic axial piston machine (1) according to claim 3, characterized by the fact that the first actuating piston (35a) and the second actuating piston (35b) are arranged to be longitudinally displaceable in a housing bore (65) of a further valve sleeve (66), wherein the further valve sleeve (66) is detachably attached to the valve sleeve (50).

5. Hydrostatic axial piston machine (1) according to claim 4, characterized by the fact that the housing bore (51) of the valve sleeve (50) and the housing bore (65) of the further valve sleeve (66) are aligned.

6. Hydrostatic axial piston machine (1) according to claim 4 or 5, characterized by the fact thatthe second actuating piston (35b) is arranged axially adjacent to the first actuating piston (35a) in the housing bore (65) of the further valve sleeve (66).

7. Hydrostatic axial piston machine (1) according to any one of claims 3 to 6, characterized by the fact that the first actuating piston (35a) is arranged with a first end face (70a) adjacent to an end face (72) of the control slide (52) of the pressure cutting valve (15) and a second end face (70b) of the first actuating piston (35a) opposite the first end face (70a) is subjected to the pressure at the first pressure port (A).

8. Hydrostatic axial piston machine (1) according to claim 7, characterized by the fact thatthe second actuating piston (35b) is arranged with a first end face (71a) adjacent to the second end face (70b) of the first actuating piston (35a) and a second end face (71b) of the second actuating piston (35b) opposite the first end face (71a) is subjected to the pressure at the second pressure port (B).

9. Hydrostatic axial piston machine (1) according to any one of claims 4 to 8, characterized by the fact that a first control port (S1) is formed on the housing bore (65) of the further valve sleeve (66), which is connected to the first pressure port (A), and a second control port (S2) is formed, which is connected to the second pressure port (B), wherein the second control port (S2) is arranged axially spaced from the first control port (S1) in the longitudinal direction of the further valve sleeve (66).

10. Hydrostatic axial piston machine (1) according to one of claims 7 to 9, characterized by the fact thatthe second end face (70b) of the first actuating piston (35a) is formed on a pin section of the first actuating piston (35a) with a reduced diameter.

11. Hydrostatic axial piston machine (1) according to one of claims 8 to 10, characterized by the fact that the first end face (71a) of the second actuating piston (35b) is formed on a pin section of the second actuating piston (3b) with a reduced diameter.

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