Hydraulic or pneumatic actuation arrangement of a lamella switching element

Abstract

A hydraulic or pneumatic actuating arrangement with a multi-disk switching element having an actuating cylinder (8) connected to a hydraulic or pneumatic supply for actuating a disk pack of the multi-disk switching element, wherein a double-acting actuating cylinder (8) is provided with a first pressure chamber (10) associated with a first piston surface (9) and a second pressure chamber (12) associated with a second piston surface (11), wherein the two piston surfaces (9, 11) have different effective areas, wherein the first pressure chamber (10) and the second pressure chamber (12) are connected to one another during a first actuating phase to overcome a clearance (s) in the multi-disk switching element, and wherein the first pressure chamber (10) and the second pressure chamber (12) are separated from one another during a second actuating phase to close the multi-disk switching element, characterized in thatthat in the first actuation phase, the first pressure chamber (10) and the second pressure chamber (12) are subjected to a first actuation pressure (P1) of the hydraulic or pneumatic supply, and that in the second actuation phase, the first pressure chamber (10) is subjected to a second, higher actuation pressure (P2) of the hydraulic or pneumatic supply, and the second pressure chamber (12) is depressurised.

Description

[0001] The present invention relates to a hydraulic or pneumatic actuating arrangement for a multi-disk switching element. Furthermore, the invention relates to a method for actuating the actuating arrangement and a travel drive with the hydraulic or pneumatic actuating arrangement, as well as to an industrial truck or a construction machine with the travel drive.

[0002] Such a hydraulic or pneumatic actuation arrangement is installed, for example, in a transmission or an axle of a vehicle, whereby a plate pack of the multi-plate shift element is lubricated and cooled by oil. The oil present between the plates of the plate pack causes drag losses, which arise from the shearing of the oil of the plates of the plate pack located between the friction partners. The plate pack consists of outer plates and inner plates, which are arranged so as to be axially displaceable and are pressed against one another by appropriate axial actuation, thus creating a frictional or non-positive connection when the multi-plate shift element is switched on. When the multi-plate shift element is open, there is an axial play between the plates, which is referred to as the air gap.However, as soon as a speed difference exists between the plates of the plate pack, an undesirable drag torque occurs. There are many possible ways to reduce this drag torque. In particular, the drag torque can be reduced by increasing the clearance in the plate pack, thereby reducing the shear forces between the plates of the plate pack. However, it should be noted that increasing the clearance also increases the actuation travel of the plate switching element for switching or closing, which also undesirably increases the actuation volume of the hydraulic or pneumatic fluid.

[0003] DE 10 2006 055 009 A1 relates to a hydraulic disc brake with an electromechanical actuator and a hydraulic adjustment gear, which has a larger travel ratio to overcome a clearance and automatically switches to a smaller travel ratio and thus a larger power ratio when friction brake pads are in contact with a brake disc.

[0004] DE 10 2010 042 657 A1 relates to a shifting device for performing a shifting operation of a vehicle transmission, in particular in an automatic transmission or an automated manual transmission, comprising a shifting element that can be compressed or brought together by a pressurizable piston. The piston has two pressurizable piston surfaces that are successively subjected to pressure in two phases during the shifting operation. In the first phase, the shifting element is preloaded, and in the second phase, it is compressed or brought together.

[0005] US 2016 / 010 706 A1 discloses a method for quickly connecting or engaging a separate hydraulic disc clutch in a four-wheel drive vehicle, wherein the disc clutch has a hydraulic cylinder for its actuation, wherein the effective piston area in the cylinder is reduced during the connection phase.

[0006] The present invention is based on the object of creating an actuating arrangement and a method for actuating the actuating arrangement as well as a travel drive with the actuating arrangement and an industrial truck or a construction machine vehicle with the travel drive, in which the smallest possible actuating volume is realized with the smallest possible drag torque.

[0007] This object is achieved according to the invention by the features of patent claim 1 or 10 or 11 or 12, wherein advantageous and claimed developments result from the subclaims and the description as well as the drawings.

[0008] Thus, a hydraulic or pneumatic actuation arrangement of a multi-plate shift element is proposed, comprising an actuation cylinder connected to a hydraulic or pneumatic supply for actuating a plate pack of the multi-plate shift element. The actuation arrangement comprises a double-acting actuation cylinder with a first pressure chamber associated with a piston surface and a second pressure chamber associated with a second piston surface. The two piston surfaces have different effective areas. The first pressure chamber and the second pressure chamber are connected to one another during a first actuation phase to overcome a clearance in the plate pack, and the first pressure chamber and the second pressure chamber are separated from one another during a second actuation phase to close the multi-plate shift element.

[0009] In this way, a differential cylinder is proposed as a double-acting actuating cylinder in which the differential effect, i.e. the actuation of two piston surfaces, can be switched off. Due to the differently dimensioned active surfaces, it is possible to pressurise both interconnected pressure chambers of the differential cylinder or the actuating cylinder with hydraulic or pneumatic medium at a low initial actuation pressure that is sufficient to overcome the clearance in the plate pack. With a small actuation volume, a large piston travel or actuation travel can be covered and thus the clearance can be overcome. The piston force is low but sufficient to overcome the clearance. If, for example, a defined actuation pressure or a defined actuation travel is exceeded, the two pressure chambers can be separated from one another.One of the pressure chambers is further pressurized with a second actuation pressure that is higher than the first actuation pressure. While the other pressure chamber is depressurized or pressurized with a significantly lower pressure than the actuation pressure. This means that the full piston area is available for actuation. The actuation force is correspondingly high. The piston travel per actuation volume is small, but since the clearance has already been overcome, only a very short piston travel or actuation travel needs to be covered in this operating state, for example, to compensate for any compliance in the actuation.

[0010] Consequently, with the proposed actuation arrangement, the required hydraulic or pneumatic fluid volume can be reduced by a factor of > 10 for the same piston force. This has the advantage that the clearance can be increased, if necessary, to reduce the drag torque. Furthermore, it is possible to compensate for any wear that occurs on the multi-plate switching element by increasing the actuation travel accordingly, since the proposed actuation arrangement enables corresponding reserves through the saved actuation volume. Furthermore, with the proposed actuation arrangement, actuation can be ensured without additional actuation pressure boosters or other additional components. Overall, the reduced drag torque can reduce losses and heating as well as wear on the multi-plate switching element.

[0011] In the proposed actuation arrangement, according to the invention, in the first actuation phase, the first pressure chamber and the second pressure chamber can be subjected to a first actuation pressure in order to overcome the clearance, and in a second actuation phase, the first pressure chamber can be subjected to a second, higher actuation pressure and the second pressure chamber can be depressurized.

[0012] A structurally simple embodiment of the double-acting actuating cylinder in the actuating arrangement according to the invention is achieved in that the first piston surface corresponds to a first end face of the piston and that the second piston surface is provided on a second end face of the piston, wherein the effective area of ​​the second piston surface is reduced by the area of ​​a piston rod operatively connected to the plate pack. This results in an annular area as the second piston surface due to the centrally arranged piston rod, while the first piston surface corresponds to the entire end face of the piston. Thus, with the same pressure applied to both piston surfaces, the larger first piston surface enables the piston to move to overcome the clearance.

[0013] In order to provide the previously described switching in the double-acting actuating cylinder or in the differential cylinder, in order to switch between the first actuating phase and the second actuating phase, the proposed actuating arrangement comprises at least one directional control valve that can be switched depending on pressure or actuating travel. In this way, the connection between the two pressure chambers can be established or the two pressure chambers can be separated from each other by switching the directional control valve accordingly when a predetermined actuating pressure or actuating travel is reached.

[0014] Within the scope of a preferred embodiment of the invention, a multi-disk brake of a traction drive is provided as the multi-disk switching element. To actuate the multi-disk brake, the hydraulic or pneumatic supply is connected to a brake cylinder or a master brake cylinder for applying an actuating pressure or a braking pressure. The actuating pressure can then be used to apply the pressure chambers described above to actuate the multi-disk brake.

[0015] The hydraulic or pneumatic supply can have a fluid or a gas as the actuating medium, wherein the actuating medium is conveyed from the brake cylinder to the actuating cylinder. For this purpose, the first pressure chamber can be connected to the brake cylinder via a first pressure line for pressurization. Accordingly, the first pressure chamber is pressurized with the corresponding actuating pressure when the brake cylinder is actuated. In order to be able to pressurize the second pressure chamber during the first actuation phase, the second pressure chamber can be connected, for example, either via a second pressure line and the switchable directional control valve to the brake cylinder for pressurization or to a reservoir. Accordingly, with the directional control valve switched accordingly, a connection can be created between the second pressure chamber and the first pressure chamber and the brake cylinder.In the second actuation phase, the connection between the first and second pressure chambers is separated by appropriate switching of the directional control valve and the second pressure chamber is connected to a reservoir, for example for pressure equalization.

[0016] In one possible variant of the hydraulic or pneumatic supply design, the second pressure line of the second pressure chamber can be connected to a pressure accumulator. This allows pressure equalization in the second pressure chamber during the second actuation phase.

[0017] However, it is also conceivable that the second pressure line can be connected to the reservoir directly or via the directional control valve. Thus, various options are conceivable within the framework of the design of the hydraulic or pneumatic supply in the proposed actuation arrangement to implement the actuation in the actuation arrangement.

[0018] A next aspect of the present invention is to claim a method for actuating the above-described hydraulic or pneumatic actuating arrangement of the multi-disk switching element, whereby the above-described and further advantages are obtained.

[0019] It is provided that in order to actuate the plate pack of the plate switching element, the double-acting actuating cylinder for actuating a plate pack of the plate switching element is actuated by a double-acting actuating cylinder with piston surfaces having different effective surfaces in such a way that during a first actuation phase, in order to overcome a clearance in the plate pack, a first pressure chamber and a second pressure chamber are connected to one another and that during a second actuation phase, in order to close the plate switching element, the first pressure chamber and the second pressure chamber are separated from one another.

[0020] According to the invention, in the proposed method, in the first actuation phase, the first pressure chamber and the second pressure chamber are pressurized with the first actuation pressure of the hydraulic or pneumatic supply, and in the second actuation phase, the first pressure chamber is pressurized with the second, higher actuation pressure of the hydraulic or pneumatic supply, and the second pressure chamber is depressurized.

[0021] A further aspect of the present invention is to claim a travel drive with the hydraulic or pneumatic actuation arrangement described above. For example, the travel drive can be used for any vehicle in which, for example, the multi-disk shift element or multi-disk brake is used in a transmission housing to decelerate the vehicle.

[0022] A further aspect of the present invention provides for an industrial truck or a construction vehicle to be equipped with the aforementioned drive system. Consequently, forklifts or construction machinery, for example, can be braked accordingly.

[0023] The present invention is further explained below with reference to the drawings.

[0024] They show: Fig. 1 a sectional view of a travel drive according to the invention with an actuating arrangement according to the invention for a forklift truck; Fig. 2 a schematic sectional view of a first embodiment of a hydraulic or pneumatic actuating arrangement in a first actuating phase for overcoming a clearance; Fig. 3 a schematic sectional view of the first embodiment of the hydraulic or pneumatic actuating arrangement in a second actuation phase; Fig. 4 a schematic sectional detailed view of a double-acting actuating cylinder of the actuating arrangement according to the invention; Fig. 5 a schematic sectional view of a second embodiment of the hydraulic or pneumatic actuating arrangement according to the invention in the first actuating phase; Fig. 6 a schematic sectional view of the second embodiment of the hydraulic or pneumatic actuating arrangement according to the invention in the second actuating phase; Fig. 7 is a schematic sectional view of a third embodiment of the hydraulic or pneumatic actuating arrangement according to the invention in the first actuation phase; and Fig. 8 a schematic sectional view of the third embodiment of the hydraulic or pneumatic actuating arrangement according to the invention in the second actuation phase.

[0025] In Fig. 1 shows an example of a travel drive with a hydraulic or pneumatic actuation arrangement according to the invention for a multi-disk brake 1 of a forklift truck. The travel drive is typically used in pairs on the front axle of counterbalanced forklift trucks. The travel drive comprises a gearbox and a drive motor (not shown in detail), e.g., an electric motor. The gearbox, in turn, comprises a spur gear stage 2, which has a drive pinion 3 and a spur gear 4. An inner disk carrier 5 of the multi-disk brake 1 is fixedly connected to the spur gear 4. The spur gear 4 and the inner disk carrier 5 of the multi-disk brake 1 rotate about a common axis and are mounted by means of a bearing. The inner disk carrier 5 has a toothing as a sun gear 6 of a planetary gear stage. The drive power is transmitted from an electric motor (not shown in detail) to the drive pinion 3 and from there to the spur gear 4.From there, the drive power flows via the inner disk carrier 5 and the planetary gear stage to the output flange 7, to which a vehicle wheel (not shown) is attached.

[0026] In Fig. Figure 2 shows a section of the transmission with the hydraulic or pneumatic actuation arrangement of the multi-disk brake 1 according to the invention. The actuation arrangement comprises an actuation cylinder 8 connected to a hydraulic or pneumatic supply for actuating a disk set of the multi-disk switching element or the multi-disk brake 1. The actuation cylinder 8 is designed as a differential cylinder or as a double-acting actuation cylinder 8 with a first pressure chamber 10 assigned to a first piston surface 9 and a second pressure chamber 12 assigned to a second piston surface 11. The two piston surfaces 9, 11 have differently dimensioned effective surfaces.The first pressure chamber 10 and the second pressure chamber 12 are connected to one another during a first actuation phase in order to overcome a clearance s in the disk set of the multi-disk brake 1, wherein the first pressure chamber 10 and the second pressure chamber 12 are separated from one another during a second actuation phase in order to close the multi-disk brake 1.

[0027] In Fig. 2 shows the first operating state, while Fig. 3 shows the second actuation state. In the second actuation state, the drive can be mechanically braked using the disk pack of the multi-disk brake 1. The disk pack consists of stationary disks 13, which are connected in a rotationally fixed but axially movable manner to the ring gear 14 of the planetary stage, which is fixed to the housing, and of rotating disks 15, which are connected in a rotationally fixed but axially movable manner to the rotating inner disk carrier 5. The stationary disks 13 and the rotating disks 15 are arranged coaxially and alternately with one another. The stationary disks 13 are provided with a friction lining on both end faces. The outer diameter of the rotating disks 15 is larger than the inner diameter of the stationary disks 13. Furthermore, the outer diameter of the stationary disks 13 is larger than the inner diameter of the rotating disks 15.This creates a common friction surface in the axial direction between adjacent stationary plates 13 and rotating plates 15. There is also a friction surface between the thrust plate 16 and the adjacent stationary plate 13. The plate pack is located between the thrust plates 16, 17. The non-axially movable thrust plate 17 is connected to the ring gear 14 and is thus fixed to the housing. The thrust plate 16 is axially movable. It rotates around the common axis together with the spur gear 4, the inner plate carrier 5 and the rotating plates 15. The clear distance between the thrust plates 16, 17 is greater than the sum of the thicknesses of all plates 13, 15. The difference is the clearance s. The compression springs 18 press the thrust plate 16 in the axial direction against the spur gear 4 in order to maintain the clearance s when the multi-disk brake 1 is open.

[0028] The transmission housing contains oil, which also flows between the stationary plates 13 and the rotating plates 15. When open, the rotating plates 15 can rotate freely relative to the stationary plates 13. However, due to the shear forces acting in the oil in the air gaps between the plates 13, 15, a drag torque is created, which leads to transmission losses during power transmission. The air gap s can be set larger when using the actuating arrangement according to the invention than with a conventional actuating arrangement, without requiring more actuating volume for brake actuation.

[0029] As already described, the actuation process of the hydraulic or pneumatic actuation arrangement of the multi-disk brake 1 consists of two actuation phases, regardless of the respective design variants. The first actuation phase enables the clearance s to be overcome. In the first actuation phase, a long piston travel or actuation travel is required, but only a low actuation force. For example, in Fig. 2, Fig. 5 and Fig. 7, the illustrated master brake cylinder or brake cylinder 19 generates a first actuation pressure P1 and a corresponding volume flow, which is present in both pressure chambers 10, 12. The first actuation pressure P1 is transmitted via a supply line 20 to the hydraulic supply or pneumatic supply. Depending on whether a fluid or a gas is used as the actuation medium, this is a hydraulic or pneumatic supply. As long as a volume flow is flowing, the required actuation pressure is low. Via a directional control valve 21, a first pressure line 22, which is connected to the first pressure chamber 10, and a second pressure line 23, which is connected to the second pressure chamber 12, are short-circuited with one another, i.e. connected, as soon as the first actuation phase occurs. As a result, the first actuation pressure P1 is present in both the first pressure chamber 10 and the second pressure chamber 12.

[0030] According to Fig. 4 clearly shows that the first piston surface 9 of the first pressure chamber 10 corresponds to the first end face of the piston 24, with the second piston surface 11 of the second pressure chamber 12 being provided on the second end face of the piston 24. Accordingly, the first piston surface 9 corresponds to the entire first end face of the piston 24 with the diameter D. The second piston surface 11 of the second pressure chamber 12, in contrast, corresponds to the second end face minus the area of ​​the piston rod 25 with the diameter d. Consequently, the effective area of ​​the first piston surface 9 is the entire end face of the piston 24, while the effective area of ​​the second piston surface 11 corresponds to an annular area reduced by the area of ​​the piston rod 25. Consequently, the first piston surface 9 of the first pressure chamber 10 is larger than the second piston surface 11 of the second pressure chamber 12.Thus, the piston 24 moves toward the second pressure chamber 12 due to the first actuating pressure P1 present in both pressure chambers 10, 12, since the effective area of ​​the second piston surface 11 is smaller. Via the piston rod 25 of the piston 24 of the actuating cylinder 8, an axial plain bearing 33 and thus the thrust washer 16 are moved toward the vanes 13, 15 until the clearance is overcome.

[0031] During the second phase of activity, which for example takes place in Fig. 3, Fig. 6 and Fig. 8, the closing of the multi-disk brake 1 is initiated after the air gap s has been overcome. The directional control valve 21 switches when a certain actuating pressure or when a certain actuating travel is reached, so that the first pressure line 22 with the first pressure chamber 10 is separated from the second pressure line 23 with the second pressure chamber, so that a second, higher actuating pressure P2 is only present in the first pressure chamber 10, while the second pressure chamber 12 is depressurized because it is separated from the supply line 20 of the brake cylinder 19. The piston travel or the actuating travel is very small in the second actuation phase because only compliances in the system are compensated for. Consequently, the disk set of the multi-disk brake 1 is closed and a braking torque is built up between the inner disk carrier 5 and the ring gear 14 fixed to the housing.

[0032] The second pressure chamber 12 is in the first embodiment according to Fig. 2 and Fig. 3 is connected to a pressure accumulator 26. The pressure accumulator 26 can absorb the volume of the actuating medium from the second pressure chamber 12 during the second actuation phase, so that the first actuation pressure P1 present from the first actuation phase is reduced during the second actuation phase.

[0033] In Fig. Figure 4 shows a detailed view of the actuating cylinder 8, which illustrates the previously described structure. This shows the two pressure chambers 10 and 12 with the differently dimensioned piston surfaces 9, 11.

[0034] In Fig. 5 and Fig. 6 shows a second embodiment of the hydraulic or pneumatic actuation arrangement. Fig. 5 shows the first actuation phase, while Fig. 6 shows the second actuation phase.

[0035] In the second variant according to Fig. 5 and Fig. 6, no pressure accumulator 26 is connected to the second pressure line 23. Instead, the second pressure line 23 is connected to a reservoir 29 via a first check valve 27 and a third pressure line 28. Furthermore, the directional control valve 21A differs in its function from the directional control valve 21 according to Fig. 2 and Fig. 3.

[0036] In the first actuation phase, the first pressure line 22 and the second pressure line 23 are short-circuited via the directional control valve 21A, so that the first pressure chamber 10 and the second pressure chamber 12 are connected to the supply line 20 of the brake cylinder 19 and the first actuation pressure P1 is present in both pressure chambers 10, 12. Fig. In the second actuation phase shown in Figure 6, the second pressure line 23 is switched via the directional control valve 21A after reaching the predetermined limit value for the actuation pressure or the actuation travel such that the second pressure line 23 is connected to the reservoir 29 via the switched directional control valve 21A, via a second check valve 31, and via a fourth pressure line 30. The second check valve 31 prevents air from entering the system. The fourth pressure line 30 can divert the oil or air, which is still displaced from the second pressure chamber 12 during the second actuation phase, e.g., into the reservoir 29. If the actuation pressure is reduced, the piston 24 moves back slightly.To ensure that no negative pressure develops in the second pressure chamber 12 when the actuating pressure is reduced, the first check valve 27 is provided in the third pressure line 28, which can feed oil or air from the reservoir 29 into the second pressure line 23 via the third pressure line 28. This prevents a negative pressure in the second pressure chamber 12.

[0037] In the Fig. 7 and Fig. 8 shows a third embodiment of the hydraulic or pneumatic actuation arrangement. In Fig. 7 is the first activation phase and in Fig. 8 shows the second actuation phase. The directional control valve 21 corresponds to the directional control valve 21 in the first embodiment according to Fig. 2 and Fig.3. In the third embodiment, the actuating medium can be directed from the second pressure chamber 12, for example, via a spring-loaded check valve 32 into the reservoir 29. The opening pressure of the spring-loaded check valve 32 must be greater than the switching pressure of the directional control valve 21. This is because the spring-loaded check valve 32 may only open when the first pressure chamber 10 is separated from the second pressure chamber 12 via the directional control valve 21. To avoid a negative pressure in the second pressure chamber 12 when the actuating pressure is reduced, a first check valve 27 can also be provided in this third embodiment in a third pressure line 28, which is connected to the reservoir 29. The spring-loaded check valve 32 is connected to the reservoir 29 via the fourth pressure line 30. Reference symbol 1 multi-disk brake 2 spur gear stage 3 drive pinions 4 spur gear 5 inner disc carriers 6 Sun gear 7 Output flange 8 actuating cylinders 9 first piston surface 10 first printing room 11 second piston surface 12 second pressure chamber 13 vertical slats 14 ring gear 15 rotating slats 16 thrust washer 17 thrust washer 18 compression spring 19 brake cylinders 20 supply line 21, 21A directional control valve 22 first pressure line 23 second pressure line 24 pistons 25 Piston rod 26 pressure accumulators 27 first check valve 28 third pressure line 29 storage containers 30 fourth pressure line 31 second check valve 32 spring-loaded check valve 33 axial plain bearings s Release clearance of the multi-disk brake d Diameter of the piston rod D Diameter of the piston P1 first actuation pressure in the first actuation phase P2 second higher actuation pressure in the second actuation phase

Claims

[1] Hydraulic or pneumatic actuating arrangement with a multi-disk switching element with an actuating cylinder (8) connected to a hydraulic or pneumatic supply for actuating a disk pack of the multi-disk switching element, wherein a double-acting actuating cylinder (8) is provided with a first pressure chamber (10) associated with a first piston surface (9) and a second pressure chamber (12) associated with a second piston surface (11), wherein the two piston surfaces (9, 11) have different effective areas, wherein the first pressure chamber (10) and the second pressure chamber (12) are connected to one another during a first actuating phase to overcome a clearance (s) in the disk pack and wherein the first pressure chamber (10) and the second pressure chamber (12) are separated from one another during a second actuating phase to close the multi-disk switching element, characterized bythat in the first actuation phase the first pressure chamber (10) and the second pressure chamber (12) are subjected to a first actuation pressure (P1) of the hydraulic or pneumatic supply and that in the second actuation phase the first pressure chamber (10) is subjected to a second, higher actuation pressure (P2) of the hydraulic or pneumatic supply and the second pressure chamber (12) is depressurized. [2] Hydraulic or pneumatic actuating arrangement according to claim 1, characterized by that the first piston surface (9) corresponds to a first end face of the piston (24) and that the second piston surface (11) is provided on a second end face of the piston (24), wherein the effective surface of the second piston surface (11) is reduced by an area of ​​a piston rod (25) which is in operative connection with the plate pack. [3] Hydraulic or pneumatic actuating arrangement according to one of the preceding claims, characterized bythat a directional control valve (21, 21A) which can be switched depending on the pressure or actuation path is provided for switching between the first actuation phase and the second actuation phase. [4] Hydraulic or pneumatic actuating arrangement according to one of the preceding claims, characterized by that a multi-disk brake (1) of a travel drive is provided as the multi-disk switching element. [5] Hydraulic or pneumatic actuating arrangement according to one of the preceding claims, characterized by that the hydraulic or pneumatic supply is connected to a brake cylinder (19) for applying the actuating pressure. [6] Hydraulic or pneumatic actuating arrangement according to claim 5, characterized by that the first pressure chamber (10) is connected to the brake cylinder (19) via a first pressure line (22) for pressurization. [7] Hydraulic or pneumatic actuating arrangement according to one of the preceding claims, characterized bythat the second pressure chamber (12) can be connected via a second pressure line (23) and via the directional control valve (21, 21A) to the brake cylinder (19) for pressurization or to a reservoir (29). [8] Hydraulic or pneumatic actuating arrangement according to claim 6 or 7, characterized by that the second pressure line (23) is connected to a pressure accumulator (26). [9] Hydraulic or pneumatic actuating arrangement according to claim 7 or 8, characterized by that the second pressure line (23) can be connected to the storage tank (29) directly or via the directional control valve (21,21A). [10] Method for actuating a hydraulic or pneumatic actuating arrangement according to one of the preceding claims, wherein, for actuating a disk pack of the disk switching element, a double-acting actuating cylinder (8) with piston surfaces (9, 11) having different effective areas is controlled in such a way that, during a first actuation phase, a first pressure chamber (10) and a second pressure chamber (12) are connected to one another to overcome a clearance (s) in the disk pack, and that, during a second actuation phase, the first pressure chamber (10) and the second pressure chamber (12) are separated from one another to close the disk switching element, characterized bythat in the first actuation phase the first pressure chamber (10) and the second pressure chamber (12) are subjected to a first actuation pressure of the hydraulic or pneumatic supply and that in the second actuation phase the first pressure chamber (10) is subjected to a second, higher actuation pressure of a hydraulic or pneumatic supply and the second pressure chamber (12) is depressurized. [11] Travel drive with a hydraulic or pneumatic actuating arrangement according to one of claims 1 to 9. [12] Industrial truck or construction vehicle with a drive according to claim 11.

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