Control device for driving direction control for a soil compactor and soil compactors with such a control device

Abstract

Control device for driving direction control for a soil compactor (2) with - a hydraulic head (24) which has a housing (26) in which a hydraulic piston (28) which is axially displaceable (30) within a cylinder (34) is arranged, - an excitation unit (4) to which the hydraulic head (24) is connected via a hydraulic line (12) for controlling the direction of travel, - a flow path (40) for a hydraulic fluid between a compensation chamber (36) and the hydraulic line (12), which can be closed via the hydraulic piston (28), - a control lever (22) via which the hydraulic piston (28) can be actuated, so that it is adjusted in the axial direction (30) and thereby transmits a control pressure to the excitation unit (4) by means of the hydraulic fluid to change the direction of travel, characterized in that - in the cylinder (34) at least one overflow opening (42) is formed as part of the flow path (40), wherein the overflow opening (42) can be reversibly closed by the hydraulic piston (28) depending on its axial position.

Description

[0001] The invention relates to a control device for controlling the direction of travel for a reversible soil compactor having the features of the preamble of claim 1, as well as to a soil compactor with such a control device. Such a soil compactor can be found in DE 20 2021 103 447 U1.

[0002] The soil compactor is also known as a vibrating plate or vibrating compactor. Such soil compactors generally have an exciter unit with a base plate attached to it. The exciter unit has two unbalanced shafts with centrifugal weights, and the phase position and thus the relative rotational position of the two unbalanced shafts is adjustable. For this purpose, the two unbalanced shafts are typically connected to each other via a gear, which is designed as a ring gear, in particular with an internal worm thread. The gear is hydraulically axially adjustable with the help of a control piston arranged in the exciter unit, with the axial movement being converted into a rotary movement by the worm thread to adjust the phase position. The phase or rotational position of the two shafts and thus the direction of travel can be continuously changed.

[0003] During operation, the two unbalanced shafts generate counterpressure, pushing the gear into a first end position. Typically, the excitation unit is designed such that this first end position is a position where maximum forward movement is set.

[0004] The control piston in the exciter unit is connected via a hydraulic line to a hydraulic head in which a hydraulic piston is arranged so that it can be displaced in an axial direction. This hydraulic piston forms a master piston, via which a hydraulic control pressure can be exerted on the control piston of the exciter unit. This control pressure counteracts the counterpressure generated by the unbalanced shafts and thus allows the gear to be moved toward a second end position, in which maximum movement in the opposite direction, in particular a reverse movement, is set. In general, the hydraulic piston in the hydraulic head therefore serves to continuously adjust the direction of travel of the soil compactor.

[0005] The hydraulic piston is mechanically actuated, for example, by a control lever, which can be designed as a simple lever or a retaining bracket. To actuate and adjust the hydraulic piston, a closable flow path is required between the hydraulic line and a compensation chamber for the hydraulic fluid in the hydraulic head.

[0006] In the control device known from DE 20 2021 103 447 U1, the hydraulic head has an integrated valve pin that can be moved relative to the rest of the hydraulic head and pressed against a valve seat to open and close the flow path. This occurs when the control lever is actuated, with its movement being transmitted to the valve pin via an actuating lever specially designed as a roller lever. The valve pin itself is mounted against the spring force of a valve spring, which exerts a force toward an open position.

[0007] Overall, this creates a complex mechanism for opening and closing the flow path, with high quality requirements to ensure reliable opening and especially closing in all operating situations.

[0008] Based on this, the invention is based on the object of providing a simply constructed control device in which a reliable opening and closing of the flow path is possible with little effort.

[0009] The object is achieved according to the invention by a control device for controlling the direction of travel for a reversible soil compactor having the features of claim 1 and by a soil compactor having such a control device.

[0010] The soil compactor is a soil compactor as described above. The control device has a hydraulic head with a housing in which the axially displaceable hydraulic piston is arranged as the master piston. The hydraulic head is connected via a hydraulic line to an excitation unit for controlling the direction of travel. Furthermore, a flow path for a hydraulic fluid between an escape chamber for the hydraulic fluid and the hydraulic line can be reversibly closed via the hydraulic head. Furthermore, a control lever, in particular manually operable, for example in the manner of a bracket, is provided, via which the hydraulic piston can be actuated so that it is adjusted in the axial direction. By actuating the control lever, the movement of the control lever is transmitted to the hydraulic piston via a force element, and a force is transmitted. In particular, a mechanical power transmission is provided.By moving the hydraulic piston, a control pressure is transmitted to the exciter unit via the hydraulic line and the hydraulic fluid to change the direction of travel. Specifically, as described above, a control piston (slave piston) located at the end of the hydraulic line in the exciter unit is moved. This, in turn, adjusts the phase relationship of the two unbalance shafts, thus continuously controlling the direction of travel and the driving speed.

[0011] According to the invention, at least one overflow opening is formed in the cylinder as part of the flow path, wherein the overflow opening can be reversibly closed by the hydraulic piston depending on its axial position. The hydraulic piston therefore closes the overflow opening formed in a wall of the cylinder with its outer wall depending on its axial position. During its adjustment movement, the hydraulic piston slides along an inner wall of the cylinder and thereby closes or opens the overflow opening, so that the flow path from the hydraulic line to the compensation chamber is opened or closed.

[0012] When the control lever is operated, the direction of travel changes due to an axial displacement of the hydraulic piston, which closes at least one overflow opening and thus the flow path. Further movement of the hydraulic piston builds up the desired control pressure for the change in direction.

[0013] Compared to the known design with the valve pin centrally located within the hydraulic piston and guided relative to it, this significantly simplifies the design of the hydraulic piston. For reliable closure, for example, the formation of a sealing seat between the valve pin and the valve seat is no longer necessary. Rather, reliable closure is assured by the hydraulic piston itself.

[0014] Preferably, the piston has a circumferential sealing ring, which is arranged above (relative to the axial direction) the overflow opening when the flow path is open and below it when the flow path is closed. The sealing ring ensures a reliable seal between the piston and the inner wall of the cylinder. The sealing ring is made of an elastic material such as rubber, for example.

[0015] Preferably, the hydraulic piston has at least one recess or a reduced diameter in a lower section below the circumferential sealing ring, wherein a portion of the flow path is formed by this recess or the reduced diameter. In this section below the circumferential sealing ring, a portion of the flow path therefore runs between the hydraulic piston, specifically between an outer piston wall and the inner cylinder wall. This portion is designed, in particular, as a circumferential free annular space between the hydraulic piston and the inner cylinder wall.

[0016] Preferably, the overflow opening is designed as a purely radial bore, which extends through the cylinder wall in the radial direction or, if appropriate, at an angle to the radial direction. This bore can be formed in a simple manner.

[0017] Preferably, the cylinder is designed as a simple cylindrical sleeve or tube or bushing and has a closed cylinder wall except for the at least one overflow opening.

[0018] In general, preferably several, for example 2, 3 or 4 overflow openings are formed, which are arranged in particular evenly distributed around the circumference.

[0019] In a preferred embodiment, the overflow openings open into a flow chamber that runs annularly around the cylinder. This flow chamber is connected to the compensation chamber for the hydraulic fluid or is part of it. Therefore, at least an upper portion of the cylinder extends into this annular flow chamber. This is particularly designed concentrically to the cylinder.

[0020] Preferably, the hydraulic piston is formed in one piece—if applicable, except for the additional sealing ring described above. Specifically, it has no parts that move relative to one another. The hydraulic piston is designed, in particular, as a monolithic component. This allows for simple manufacturing and also achieves a robust design.

[0021] In a preferred embodiment, the hydraulic piston has a control pin at its upper end. This pin is, in particular, part of the previously described one-piece and, in particular, monolithic hydraulic piston. During operation, an actuating lever acts on this control pin to actuate the hydraulic piston.

[0022] This operating lever is operated in particular via the control lever described above.

[0023] Preferably, at least one spring element is provided, which exerts a restoring force on the piston acting in the axial direction, counteracting a counterpressure generated by the excitation unit. The particular advantage of this design is that it improves both the control of the direction of travel and the safety properties. Since the spring element exerts a counterforce on the hydraulic piston, which counteracts the counterpressure generated by the excitation unit, switching between the directions of travel and controlling the speed can be easily controlled. Furthermore, in a release position, when the control lever is not actuated and no force is exerted via it, uncontrolled movement is avoided.It is ensured that the hydraulic piston assumes a defined position so that a controlled movement of the soil compactor is automatically established, especially in the forward direction, and an uncontrolled speed, especially forward speed, is avoided.

[0024] As described above, due to their design, a hydraulic backpressure builds up through the two unbalanced shafts, which acts on the hydraulic piston in the opposite direction to the axial direction. Since such soil compactors are typically operated at maximum engine power of the exciter unit and thus at maximum speed of the unbalanced shafts, a high backpressure typically builds up.

[0025] Preferably, the spring force of the spring element is dimensioned such that – in the described release position, i.e., in the absence of forced actuation by the control lever – the hydraulic piston is held in an axial intermediate position against the counterpressure. This prevents the counterpressure from pushing the hydraulic piston into an end position in which a maximum speed, especially in the forward direction, would occur. This axial intermediate position is therefore a safety position.

[0026] The spring force, and thus the resulting intermediate position, is preferably selected such that the soil compactor only moves forward at a defined, low speed, despite the exciter unit's motor running at full speed. This measure provides reliable anti-pinch protection. If, for example, the user is at risk of becoming trapped during a reverse movement, for example due to loss of control, the direction of travel is automatically reversed by releasing the control lever. This is because the counterpressure generated and the spring force defined by the spring element change the direction of travel to a controlled forward movement at a slow speed.

[0027] Preferably, the control lever is connected to a rotary shaft in a rotationally fixed manner and acts on the hydraulic piston via this shaft to adjust it in the axial direction. The control lever is thus adjusted around a rotational axis to change the direction of travel; this rotational movement is transmitted via the rotary shaft and leads to the mechanical forced adjustment of the hydraulic piston in the axial direction.

[0028] The at least one spring element is preferably a leg spring or torsion spring, one leg of which is supported directly or indirectly on the rotary shaft, and the other leg of which is supported directly or indirectly on the housing. The design as a leg spring is particularly favorable and advantageous from a structural point of view. This exerts a restoring torque on the rotary shaft, which counteracts the counterpressure generated by the excitation unit.

[0029] The rotary shaft preferably continues through the leg spring. This allows for a space-saving arrangement. The rotary shaft excels by extending completely through the housing. The rotary shaft thus protrudes from both sides of the housing, with a leg spring arranged on each side of the housing and thus outside the housing. This ensures sufficient restoring force while maintaining an overall compact design.

[0030] The at least one leg spring, and preferably both leg springs, are each sealed within a bushing, which has (only) an annular gap through which, for example, moisture can escape. The gap is kept so small that no dirt particles can penetrate the interior of the bushing.

[0031] The spring element is preferably located outside the housing. The housing generally defines a hydraulic chamber, which also contains, among other things, the hydraulic fluid. Therefore, the spring element does not come into contact with the hydraulic fluid.

[0032] To transmit the mechanical force from the control lever to the hydraulic piston, the aforementioned actuating lever, specifically a roller lever, is also provided. This roller lever is connected to the rotary shaft and acts at least indirectly on the hydraulic piston. Specifically, this roller lever acts on the previously explained control pin of the hydraulic piston.

[0033] Additionally, a compression spring is provided that acts on the hydraulic piston in the opposite direction to the axial direction. The compression spring exerts a force on the hydraulic piston in the opposite direction to the axial direction, particularly in the direction of an upper stop for the hydraulic piston.

[0034] The hydraulic piston is generally infinitely adjustable from an upper position to a lower position using the control lever. Preferably, the upper position is limited and defined by an upper stop, and the lower position by a lower stop.

[0035] An embodiment of the invention is explained in more detail below with reference to the figures. These show Fig. 1 a side view, partly in section, of a soil compactor, Fig. 2 a sectional view through an excitation unit of the Fig. 1 soil compactor, Fig. 3 a partial view of a hydraulic head to which a control lever designed in the manner of a bracket is rotatably attached, Fig. 4 a sectional view through the hydraulic head along the section line AA according to Fig. 3 Fig. 5 a sectional view along the section line BB in Fig. 4, Fig. 6A a sectional view along the section line CC according to Fig. 4, where the hydraulic piston is in an upper position and Fig. 6B a sectional view analogous Fig. 6A, with the hydraulic piston in a lower position.

[0036] The Fig. 1 soil compactor 2 regularly has a further Fig. 2 shown excitation unit 4 with a base plate 6 attached thereto. As can be seen in particular from Fig. As can be seen in Figure 2, the exciter unit 4 has two unbalanced shafts 8 driven by a motor. A control bar 20 is attached to the exciter unit 4, which usually has a handlebar at its upper end for operating the soil compactor 2. This also forms a control lever 22 for controlling the direction of travel.

[0037] A hydraulic line 12 is arranged inside the control bar 20, via which a hydraulic pressure is transmitted to a control piston 14 in the excitation unit 4 for controlling the direction of travel.

[0038] The control lever 22 is rotatably mounted on a hydraulic head 24. The Fig. The position of the control lever 22 shown in Figure 1 is a (front) end position, in which the control lever 22 is manually pushed to the maximum forward position, allowing the soil compactor to move at maximum forward speed. From this position, the control lever 22 can be moved counterclockwise by the operator to a second (rear) end position. This position corresponds to a maximum reverse speed.

[0039] The function and structure of the control device for driving direction control is specifically described using the sectional drawings according to the Fig. 4 and Fig. 5 explains: The hydraulic head 24 has a housing 26, which in the exemplary embodiment is constructed in several parts, particularly two parts, with a housing cover and a base housing. A hydraulic piston 28 is mounted in the housing 26 and can be displaced in the axial direction 30 from an upper end position to a lower end position. In the exemplary embodiment, the hydraulic piston 28 has a cylindrical main body, to the upper end of which an axially extending control pin 38 is connected.

[0040] In Fig. 4, the hydraulic piston 28 is in its upper end position. In this position, it is pressed, for example, against an upper stop. The hydraulic piston 28 is generally guided within a cylinder 34. A compensation chamber 36 for a hydraulic fluid is formed above the hydraulic piston 28. This compensation chamber 36 is delimited by the housing 26; specifically, it is located in the area of ​​the dividing plane between the housing cover and the base body. The hydraulic fluid can be filled into this compensation chamber via an opening that can be closed by an inlet screw.

[0041] A flow path 40 (see in particular Fig. 6A), which can be reversibly closed by means of the hydraulic piston 28, connects the hydraulic line 12 with the compensation chamber 36.

[0042] Furthermore, a compression spring 44 is arranged below the hydraulic piston 28, which exerts a spring force on the hydraulic piston 28 counter to the axial direction 30. A connector 46 is provided for connecting the fluid line 12 to the excitation unit 4.

[0043] A rotary shaft 48 is guided through the housing 26 and is connected in a rotationally fixed manner to the control lever 22. In the center and in the area of ​​the control pin 38, an actuating lever, designed in the exemplary embodiment as a roller lever 50, is rotationally fixedly attached to the rotary shaft 48, which acts with its front end on a rear end of the control pin 38.

[0044] In the in the Fig. In the position shown in Figure 4, the roller lever rests against a roller lever stop 52. The control lever 22 is pushed into this position by active actuation. In this (front) end position, there is preferably some play between the roller lever 50 and the control pin 38; at least the roller lever 50 exerts no force. The compression spring 44 pushes the hydraulic piston 28 upwards, so that the flow path 40 is opened and pressure equalization can take place if necessary (see in particular also Fig. 6A, Fig. 6B).

[0045] To control the direction of travel, the control lever 22 can be adjusted from the maximum forward position shown toward the rearward position. The corresponding rotational movement causes the roller lever 50 to act on the hydraulic piston 28, in this example via the control pin 38.

[0046] The hydraulic piston 28 initially closes an overflow opening 42 in the cylinder 34 and thus the flow path 40. This occurs in an intermediate position of the hydraulic piston 28. When the hydraulic piston 28 is moved further downwards, a control pressure is then transmitted to the excitation unit 4 via the hydraulic fluid due to the closed flow path 40, so that - as described above - the direction of travel is changed and the soil compactor 2 switches to reverse movement.

[0047] Out of Fig. Figure 5 shows the mechanics of the hydraulic head 24 in the area of ​​the rotary shaft 48, which is connected in a rotationally fixed manner to the control lever 22. It can also be seen that a leg spring 54 is arranged on each side of the housing 26 within a particularly cylindrical bushing 55. One spring leg of each spring is supported on the housing 26, indirectly via a (screw) bolt. In a similar way, the other spring leg is supported indirectly on the rotary shaft 48. For this purpose, a bolt is provided, which is connected to an annular disk 56, which is connected in a rotationally fixed manner to the rotary shaft 48. The two leg springs 54 therefore exert a restoring torque and thus a restoring force on the rotary shaft 48, which is transmitted to the hydraulic piston 28. The leg springs 54 are protected and essentially sealed in the respective bushing 55, except for an annular gap.The annular gap is formed between the socket wall and the housing 26 or an end plate attached thereto.

[0048] The control lever 22, designed as a bracket, is mechanically and rotationally fixedly connected on both sides to a rubber buffer 60 via a connecting plate 58, in this example via a screw connection. The rubber buffer 60, in turn, is rotationally fixedly connected to the previously described annular disc 56 and fixed thereto. This is achieved in particular by vulcanization. The rubber buffer 60 generally serves to isolate vibrations.

[0049] A restoring force or torque is exerted via the leg spring 54, which is transmitted to the valve pin 38 via the roller lever 50 in the axial direction 30. The spring force of the leg spring 54 is selected such that the hydraulic piston 28—when no force is exerted via the control lever 22—is pressed into a safety position or intermediate position in which the hydraulic piston 28 is in a middle position between its two end positions. This position is selected such that the control pressure thus built up in the excitation unit 4 adjusts the corresponding control piston 14 such that a slight forward movement is established.

[0050] As explained at the beginning, during operation, the exciter unit 4 generates a hydraulic counterpressure through the two imbalance shafts 8 contained therein, which generally acts from below on the hydraulic piston 28, counter to the axial direction 30. This counterforce is therefore generally reduced by the leg springs 54. This defined generation of the restoring force or the restoring torque generally serves to ensure that (at full engine speed of the exciter unit 4) the soil compactor 2 moves forward only slowly, thus preventing uncontrolled, rapid forward movement due to a possible loss of control by the operator. At the same time, the controlled forward movement prevents unintentional backward movement, thus providing anti-pinch protection.

[0051] Furthermore, the restoring force exerted also makes it easier to control the direction of travel via the control lever 22, since the force exerted from below by the counterpressure on the hydraulic piston 28 is reduced by the counterforce exerted by the leg springs 54.

[0052] The selected arrangement of the leg spring 54 virtually along the axis of rotation of the rotary shaft 48 also results in an overall compact design with a simple structural configuration.

[0053] Based on the Fig. 6A and Fig. 6B, the special design of the hydraulic head 24 with regard to the flow path 40 and its reversible opening or closing is explained below.

[0054] Fig. Figure 6A shows a situation where the flow path 40 is open and the hydraulic piston 28 is in the upper end position. Fig. 6B, in contrast, shows a situation in which the flow path 40 is closed and the hydraulic piston 28 is in the lower end position.

[0055] A section of the flow path 40 is (only) in Fig. 6A represented by the double arrow.

[0056] In the exemplary embodiment, the hydraulic piston 28 has an annular groove 62 in a lower section of the hydraulic piston 28 (in the exemplary embodiment, in the lower third, without taking into account the control pin 38). A closed, circumferential sealing ring 64 is located in this annular groove 62, which is formed in particular from a suitable elastic material such as rubber.

[0057] The cylinder 34 is designed as a simple (metallic) cylindrical bushing, which is attached to the housing 26 and, for example, is pressed into it. Below the cylinder 34, a central flow channel, particularly in the manner of a bore, is formed in the housing 26, into which the connecting piece 46 is inserted at the end. In the exemplary embodiment, the compression spring 44 is also supported on this. The compression spring 44 is therefore arranged within this flow channel and rests with its upper end on a lower contact surface of the hydraulic piston 28.

[0058] The flow channel is part of the flow path 40 and is connected via the connecting piece 46 to the hydraulic line 12 connected to it in the assembled state.

[0059] In the exemplary embodiment, the hydraulic piston 28 has a reduced diameter in its lower section below the annular groove 62, so that its cylinder wall is spaced from the inner wall of the cylinder 34, so that a free annular space is formed there, through which the hydraulic fluid can flow.

[0060] If the hydraulic piston 28 is in its upper position, as shown in Fig. 6A, the annular groove 62 is arranged above, in particular directly above, the overflow opening 42, so that the free annular space in the lower section of the hydraulic piston 28 extends to the overflow opening 42 and thereby the flow path 40 is opened via the overflow opening 42.

[0061] An annular flow chamber 66 is formed circumferentially around the cylinder 34 as part of the flow path 42. In this area, the cylinder 34 therefore projects freely into the interior of the housing 26 formed by the flow chamber 66.

[0062] The flow path 40 finally continues via free spaces in the upper area of ​​the hydraulic head 24 into the compensation chamber 36.

[0063] If the hydraulic piston 28 is pushed downward in the axial direction 30 by means of the control lever 22 (and thus via the rotary shaft 48 and the roller lever 50, which acts on the control pin 38 from above), the hydraulic piston 28 slides over the overflow opening 42. As soon as the sealing ring 64 is below the overflow opening 42, the flow path 40 is closed.

[0064] If the hydraulic piston 28 is pushed further downwards, no compensation of the hydraulic fluid takes place and a hydraulic pressure is built up, via which the control is then carried out as described above.

[0065] As can be seen from a comparison of the Fig. 6A, Fig. As can be seen in Figure 6B, a large part of the adjustment path of the hydraulic piston 28 occurs when the flow path 40 is closed. List of reference symbols 2 soil compactors 4 Excitation unit 6 Base plate 8 unbalanced shafts 12 Hydraulic line 14 control pistons 20 control spar 22 control levers 24 Hydraulic head 26 housings 28 hydraulic pistons 30 Axial direction 34 cylinders 36 Compensation space 38 Control pin 40 Flow path 42 Overflow opening 44 compression spring 46 connecting piece 48 Rotating shaft 50 roller levers 52 Roller lever stop 54 torsion spring 55 socket 56 ring disc 58 connection plate 60 rubber buffers 62 ring groove 64 Sealing ring 66 Flow space QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2021 103 447 U1 [0001, 0006]

Claims

[1] Control device for controlling the direction of travel for a soil compactor (2) with - a hydraulic head (24) having a housing (26) in which a hydraulic piston (28) is arranged that is displaceable in the axial direction (30) within a cylinder (34), - an excitation unit (4) to which the hydraulic head (24) is connected via a hydraulic line (12) for controlling the direction of travel, - a flow path (40) for a hydraulic fluid between a compensation chamber (36) and the hydraulic line (12) which can be closed via the hydraulic piston (28), - a control lever (22) via which the hydraulic piston (28) can be actuated so that it is adjusted in the axial direction (30) and thereby transmits a control pressure to the excitation unit (4) by means of the hydraulic fluid to change the direction of travel, characterized by , that - at least one overflow opening (42) is formed in the cylinder (34) as part of the flow path (40), wherein the overflow opening (42) can be reversibly closed by the hydraulic piston (28) depending on its axial position. [2] Control device according to the preceding claim, characterized by that the hydraulic piston (28) has a sealing ring (64) which is positioned above the overflow opening (42) when the flow path (40) is open and below the overflow opening (42) when the flow path (40) is closed. [3] Control device according to the preceding claim, characterized by that the hydraulic piston (28) has at least one recess or a reduced diameter as part of the flow path (40) in a lower section below the sealing ring (64). [4] Control device according to one of the preceding claims, characterized by that the overflow opening (42) is designed as a radial bore. [5] Control device according to one of the preceding claims, characterized by that the overflow opening (42) opens into a flow space (66) which runs annularly around the cylinder. [6] Control device according to one of the preceding claims, characterized by that the hydraulic piston (28) is formed in one piece - possibly except for an additional sealing ring (64). [7] Control device according to one of the preceding claims, characterized by that the hydraulic piston has a control pin (38) at its upper end, on which an actuating lever (50) acts to actuate the hydraulic piston (28). [8] Control device according to one of the preceding claims, characterized by that at least one spring element (54) is provided which exerts a restoring force acting in the axial direction (30) on the hydraulic piston (28), which counteracts a counterpressure generated by the excitation unit (4). [9] Control device according to the preceding claim, characterized by that the spring force of the spring element (54) is dimensioned such that - in the absence of forced actuation by the control lever (22) - the hydraulic piston (28) is held in an axial intermediate position against the counterpressure, which is preferably selected such that the soil compactor moves at low speed in the forward direction. [10] Control device according to one of the preceding claims, characterized by that the control lever (22) is connected in a rotationally fixed manner to a rotary shaft (48) and acts via this on the hydraulic piston (28) in order to adjust it in the axial direction (30). [11] Control device according to the preceding claim, characterized by that the at least one spring element is a leg spring (54), one spring leg of which is supported on the rotary shaft (48) and the other spring leg of which is supported on the housing (26). [12] Control device according to one of the preceding claims, characterized by that a compression spring (44) acts on the hydraulic piston (28) opposite to the axial direction (30). [13] Control device according to one of the preceding claims, characterized by that the hydraulic piston (28) is continuously adjustable from an upper position to a lower position by means of the control lever (22). [14] Soil compactor (2) with a control device according to one of the preceding claims.

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