NARROW AISLE TRUCK WITH MEASURES FOR PREVENTING MAST VIBRATIONS AND FOR COMPENSATING FOR MAST DEFORMATIONS

Abstract

The present invention involves a narrow aisle truck comprising: a vehicle body having length and width directions; wheels assigned to the vehicle body and arranged on two axes running in the width direction and configured to drive and steer the truck; a drive system configured to exert an acceleration torque on at least one of the wheels; a mast extending substantially vertically with respect to the length direction of the vehicle body between the two axes; at least one detection unit to detect at least one state parameter; at least one actuator to cause a movement of the mast relative to the vehicle body; and a control unit to: determine a current state, determine an effect of an actuation of the at least one actuator on the current state, and activate the at least one actuator to reduce a difference between the determined current state and a predetermined target state.

Claims

1. A narrow aisle truck, comprising: a vehicle body having a length direction and a width direction; wheels assigned to the vehicle body and arranged on two axes running in the width direction of the vehicle body and configured to drive and steer the narrow aisle truck when driving on a driving surface; a drive system configured to exert an acceleration torque on at least one of the wheels; a mast extending substantially vertically with respect to the length direction of the vehicle body, between the two axes, wherein the mast is movably mounted relative to the vehicle body with a bearing arrangement with respect to at least one degree of freedom of movement; at least one detection unit configured (A) to detect at least one state parameter of one or more of (i) the narrow aisle truck or (ii) surroundings of the narrow aisle truck and (B) to output corresponding data; at least one actuator configured to cause a movement of the mast relative to the vehicle body corresponding to the at least one degree of freedom; and a control unit operatively coupled to the at least one detection unit and the at least one actuator and configured to: determine a current state of the narrow aisle truck based on the at least one state parameter detected by the at least one detection unit; determine an effect of an actuation of the at least one actuator on the current state; and activate the at least one actuator so that a difference between the determined current state and a predetermined target state is reduced.

2. The narrow aisle truck of claim 1, wherein the control unit is further operatively coupled to the drive system and is further configured to: determine an effect of a modulation of the acceleration torque exerted by the drive system on at least one wheel on the current state; and control the drive system that a difference between the determined current state and a predetermined target state is reduced.

3. The narrow aisle truck of claim 1, wherein the at least one detection unit is configured to detect an inclination of one or more of the vehicle body, the mast, or the driving surface relative to a horizontal, wherein the inclination is transverse to the length direction of the narrow aisle truck.

4. The narrow aisle truck of claim 1, wherein the at least one detection unit is configured to detect, for one or more of (A) the vehicle body or (B) the mast, one or more of (i) an acceleration or (ii) a vibration.

5. The narrow aisle truck of claim 1, wherein the at least one detection unit is configured to detect a relative or absolute position of the narrow aisle truck, and wherein the detection unit is also assigned a memory unit operatively coupled to the control unit, wherein topology data pertaining to the driving surface accessible to the narrow aisle truck is stored in the memory unit.

6. The narrow aisle truck of claim 1, wherein the control unit is further configured to classify possible disturbances on the basis of the at least one state parameter detected by the at least one detection unit.

7. The narrow aisle truck of claim 1, wherein the at least one actuator comprises one or more of: a single-acting hydraulic cylinder, a double-acting hydraulic cylinder, a linear motor, a stepping motor, a threaded spindle, a rack drive, an electromagnet or a piezo element.

8. The narrow aisle truck of claim 7, wherein the at least one actuator comprises a hydraulic cylinder with a variable spring preload.

9. The narrow aisle truck of claim 1, wherein the bearing arrangement comprises a damping element configured to dampen a movement of the mast relative to the vehicle body along at least one direction.

10. The narrow aisle truck of claim 1, wherein the mast is mounted, by means of the bearing arrangement, in a floating manner with respect to a bearing plane that extends substantially vertically in the width direction of the vehicle body, wherein at least one of the at least one actuator is configured to displace the mast in the vertical direction relative to the vehicle body.

11. The narrow aisle truck of claim 1, wherein the bearing arrangement is arranged to be movable with respect to the vehicle body one of the at least one actuator.

12. The narrow aisle truck of claim 10, wherein, as a result of a coupling of the at least one actuator to the mast, an effective axis running in a substantially horizontal direction is formed for displacing the mast in the vertical direction so that an actuation of the at least one actuator to move the bearing arrangement relative to the vehicle body leads to a pivoting of the mast about the effective axis.

13. The narrow aisle truck of claim 1, wherein the mast is mounted in a floating manner with respect to a bearing plane that extends substantially vertically and in the width direction of the vehicle body, by means of the bearing arrangement, wherein the narrow aisle truck further comprises a further bearing arrangement configured to allow a pivoting of the mast about an axis extending perpendicular to the bearing plane, wherein an arranged actuator drives the pivoting.

14. The narrow aisle truck of claim 13, wherein the further bearing arrangement is also configured to allow the mast to pivot about a further axis lying in the bearing plane, wherein the bearing arrangement is arranged to be movable with respect to the vehicle body by one of the at least one actuator.

15. The narrow aisle truck of claim 13, wherein the further bearing arrangement and the at least one actuator for pivoting the mast are arranged on opposite sides of the mast with respect to the width direction of the vehicle body.

16. The narrow aisle truck of claim 15, wherein the bearing arrangement is arranged to be movable with respect to the vehicle body by one of the at least one actuator and wherein an effective axis running substantially in a horizontal direction is formed by the at least one actuator for pivoting the mast and the further bearing arrangement, wherein the narrow aisle truck comprises a coupling of the at least one actuator and the further bearing arrangement to the mast so that an actuation of the actuator to move the bearing arrangement relative to the vehicle body leads to a pivoting of the mast about the effective axis.

17. The narrow aisle truck of claim 1, wherein the mast is mounted by means of the bearing arrangement in a manner allowing only a vertical movement, wherein the mast is mounted movably with respect to the width direction of the vehicle body by means of a further bearing arrangement, wherein the at least one actuator is configured to move the mast a region of the further bearing arrangement in the width direction of the vehicle body to cause the mast to pivot by elastic torsion.

18. The narrow aisle truck of claim 17, wherein the bearing arrangement is movable with respect to the vehicle body by one of the at least one actuator and, wherein an effective axis running in a substantially horizontal direction is formed by the further bearing arrangement so that an actuation of the actuator to move the bearing arrangement relative to the vehicle body leads to a pivoting of the mast about the effective axis.

19. The narrow aisle truck of claim 1, further comprising a further bearing arrangement configured to allow the mast to pivot about a stationary pivot axis running in the length direction of the vehicle body, wherein the at least one actuator is configured to cause the mast to pivot about the pivot axis.

20. The narrow aisle truck of claim 19, wherein the further bearing arrangement is further configured to allow a movement of the mast along the pivot axis, wherein the at least one actuator comprises two actuators arranged to act on the mast at an angle to one another.

21. The narrow aisle truck of claim 1, further comprising a further bearing arrangement comprising an arcuate linear guide or a slewing ring bearing, wherein the arcuate linear guide or the slewing ring bearing is configured to pivot the mast about a pivot point arranged centrally on the mast in the width direction of the vehicle body, wherein the at least one actuator is configured to cause the mast to pivot about the pivot point.

22. The narrow aisle truck of claim 21, wherein the further bearing arrangement is further configured to allow pivoting of the mast about an effective axis running substantially horizontally in the width direction of the vehicle body through the pivot point, wherein a further actuator is arranged in such a way that an actuation of the further actuator leads to a pivoting of the mast about the effective axis.

23. The narrow aisle truck of claim 1, wherein the bearing arrangement is configured to allow pivoting of the mast about a stationary pivot axis running in the length direction of the vehicle body, the at least one actuator being configured to cause the mast to pivot about the pivot axis, wherein the pivot axis is arranged centrally with respect to the width direction of the vehicle body on an underside of the mast.

24. The narrow aisle truck of claim 23, further comprising a further bearing arrangement vertically above the bearing arrangement that allows a movement of the mast in the width direction of the narrow aisle truck.

25. The narrow aisle truck of claim 24, wherein the at least one actuator for pivoting the mast about the pivot axis and the further bearing arrangement is formed as an assembly.

26. The narrow aisle truck of claim 23, wherein the bearing arrangement is further configured to allow pivoting of the mast about an effective axis running substantially in the width direction of the vehicle body, and wherein the further bearing arrangement is arranged to be movable by a further actuator with respect to the vehicle body so that actuation of the further actuator causes the mast to pivot about the effective axis.

27. The narrow aisle truck of claim 23, wherein the bearing arrangement comprises a slewing ring bearing or a bearing pin.

28. The narrow aisle truck of claim 10, wherein the at least one actuator comprises two actuators arranged on opposite sides of the mast.

29. The narrow aisle truck of claim 20, wherein the two actuators form a triangle together with the width direction of the vehicle body.

30. The narrow aisle truck of claim 29, wherein the triangle comprises an isosceles triangle or an equilateral triangle.

31. The narrow aisle truck of claim 23, wherein the pivot axis is arranged centrally with respect to the vertical direction in the region of the wheels of the narrow aisle truck.

32. The narrow aisle truck of claim 24, wherein the further bearing arrangement comprises a roller guide.

Description

[0038] Further features and advantages of the present invention will become clear from the following description of embodiments thereof when considered together with the accompanying drawings. In detail, in the drawings:

[0039] FIGS. 1a and 1b are schematic views of an embodiment of a narrow aisle truck according to the invention, having a plurality of detection units provided thereon;

[0040] FIG. 2 is a schematic view of a hydraulic actuator with variable spring preload, as can be used in the various embodiments of narrow aisle trucks according to the invention;

[0041] FIGS. 3a and 3b show a first embodiment of a narrow aisle truck according to the invention in two schematic views;

[0042] FIGS. 4a and 4b show a second embodiment of a narrow aisle truck according to the invention in two schematic views;

[0043] FIGS. 5a and 5b show a third embodiment of a narrow aisle truck according to the invention in two schematic views;

[0044] FIGS. 6a and 6b show a fourth embodiment of a narrow aisle truck according to the invention in two schematic views;

[0045] FIGS. 7a to 7c show a fifth embodiment of a narrow aisle truck according to the invention in three schematic views;

[0046] FIGS. 8a to 8c show a sixth embodiment of a narrow aisle truck according to the invention in two schematic views; and

[0047] FIGS. 9a and 9b show a seventh embodiment of a narrow aisle truck according to the invention in three schematic views.

[0048] In FIGS. 1a and 1b, a narrow aisle truck according to the invention is first shown schematically in two different views. The narrow aisle truck is denoted by the reference numeral 10 and comprises a vehicle body 12 having a front pair of wheels 14a and 14b, which are provided on different longitudinal members 16, and a driven and steered rear wheel 18, via which the vehicle 10 stands on a driving surface U.

[0049] The axes of rotation of the front wheels 14a and 14b and of the rear wheel 18 each run in the width direction x of the vehicle 10, while the straight-ahead direction of travel of the vehicle 10 is also referred to as the length direction y.

[0050] Between the two axes of the front wheels 14a and 14b and of the rear wheel 18 in the length direction y of the vehicle 10, a mast 20 extends in a substantially vertical (z) direction, to which, in the embodiment shown in FIGS. 1a and 1b, a driver's cab 20a is connected in a vertically displaceable manner.

[0051] Due to its design with the mast 20 arranged between the axles of the front wheels 14a and 14b and the rear wheel 18, the narrow aisle truck 10 shown here is primarily suitable for use in logistics facilities in which only narrow aisles are provided between high bays in which goods are stored and can be picked by an operator located in the driver's cab 20a. It goes without saying that in alternative variants the narrow aisle truck 10 could also be designed as a driverless vehicle and consequently could be operated autonomously or remotely, with the driver's cab 20a being replaced by a corresponding structure in such variants. Furthermore, it goes without saying that the vehicle 10 can also include numerous other components which are customary for such vehicles, for example a hydraulic system which can supply some of the actuators described below.

[0052] With regard to different embodiments of the attachment and mounting of the mast 20 with respect to the vehicle body 12 by means of different variants of bearing arrangements, reference is made to the following drawings; in connection with FIGS. 1a and 1b, first we will discuss various detection units which can be used to detect at least one state parameter of the narrow aisle truck 10 and/or its surroundings, and which can be provided in different embodiments of such narrow aisle trucks 10 either singly or in any combination.

[0053] In this case, FIG. 1a first shows an inclination sensor 22 in the region of the mast 20, which can be designed, for example, as a multi-axis acceleration sensor and consequently can detect inclinations of the mast 20 about at least one of the x, y and z axes. Furthermore, respective ground sensors 24a and 24b are provided on both sides of the vehicle 10 in the width direction x, which sensors detect the properties of the driving surface U to the side of the vehicle 10, and can detect unevenness thereof.

[0054] In a similar way, further ground sensors 24c and 24d are shown in FIG. 1b, which can undertake a corresponding detection of the driving surface U in front of and behind the vehicle 10 in the length direction y thereof. In addition, FIG.. 1b shows a further acceleration or inclination sensor 26 in the region of the vehicle body 12, which can be designed as a three-axis acceleration sensor analogously to the sensor 22 assigned to the mast 20.

[0055] Further sensors not shown here but which can also be used in narrow aisle trucks according to the invention include position sensors for a relative or absolute position of the narrow aisle truck in space, for example receivers for GPS or for position determination information output by local transmitters, acceleration and speed sensors for detecting a driving status of the narrow aisle truck 10, etc.

[0056] According to the regulation or control concept of the vehicle according to the invention, the individual detection units deliver their data to a control unit 27, indicated only schematically in the drawings, which determines a current state of the vehicle 10 on the basis of the state parameters supplied in this way, determines an effect on this current state of an actuation of at least one of the actuators described below, and then controls the at least one actuator in such a way that a difference between the determined current state and a predetermined target state is reduced—wherein the latter can be defined, for example, in such a way that the mast 20, regardless of possible inclinations or unevenness of the driving surface U, and thus of the vehicle body 12 of the vehicle 10, is kept in a perfectly vertical orientation.

[0057] For this purpose, the control unit 27 can also be operatively coupled to a drive system, also not shown, of the narrow aisle truck 10, which, for example, exerts a drive torque on the vehicle 10 by means of the steered and driven rear wheel 18, and which can also cause the vehicle 10 to decelerate through braking interventions. For this purpose, the control unit 27 can determine the effect of a modulation of the acceleration torque exerted by the drive system on the rear wheel 18 on the current state, and control the drive system in such a way that a difference between the determined current state and a predetermined target state is reduced.

[0058] For the description of an example of a particularly suitable actuator type for the actuations of the mast 20 of the narrow aisle truck 10 described below, reference is also made to FIG. 2, in which a hydraulic actuator 30 with variable spring preload is shown. This comprises a first piston 42 and a second piston 44, the second piston 44 being provided to effect the actual power transmission to the corresponding component of the narrow aisle truck 10. In contrast, by means of the first piston 42, a preload is exerted on a spiral spring 46 arranged between the two pistons 42 and 44, due to a hydraulic pressure being supplied to a first hydraulic connection 48. This allows the static equilibrium or the zero position of the cylinder 30 to be established, wherein a further application of hydraulic pressure to a second pressure connection 50 triggers a movement of the second piston 44 and reduces the energy required for this by the amount of the work stored in the spring.

[0059] A first embodiment of a narrow aisle truck according to the invention, in which such an actuator can be used, is shown in FIGS. 3a and 3b and denoted there by the reference numeral 100. Here, and in the following description of further embodiments, for example with regard to the placement of possible detection units and also the directions and axes in the vehicles, reference is made to the description of FIGS. 1a and 1b, wherein equivalent or identical components of the embodiments each have the same reference numeral, increased by a multiple of 100; their description is omitted in detail in various places.

[0060] Accordingly, the narrow aisle truck 100 comprises a vehicle body 112 and a mast 120, as well as two front wheels 114a and 114b and a rear wheel 118. A driver's cab 120a is also attached to the mast 120 in a vertically displaceable manner. Furthermore, the mast 120 itself is movably mounted relative to the vehicle body 112 by means of a bearing arrangement 128—in the embodiment shown in FIGS. 3a and 3b, mounted in a floating manner in particular with regard to the x and z directions, i.e. freely, at least within a predetermined range in these directions, or mounted to be movable in a damped manner and fixed with respect to the y direction.

[0061] It is thus possible, by means of two first actuators 130a and 130b arranged between the mast 120 and the vehicle body 112, to displace the mast 120 at its connection points to the actuators 130a and 130b by a predetermined amount in the z direction in relation to the vehicle body 112 in each case, which is determined by the maximum stroke of the two actuators 130a and 130b. In this way, when the two actuators 130a and 130b are activated asymmetrically, the mast can also be tilted by a predetermined amount in the x-z plane. Since the two actuators 130a and 130b are also connected to the mast 120, for example by means of radial spherical plain bearings, in a pivotable manner, the imaginary connecting axis of the two connecting points of the actuators 130a and 130b creates an effective axis X130, which runs in the x direction and about which a pivoting of the mast 120 is also possible, which corresponds to a pitching movement of the mast 120.

[0062] In order to drive this pivoting or pitching, a further actuator 132 is also provided in the narrow aisle truck 100, which allows the bearing arrangement 128 to be displaced relative to the vehicle body 112 in the y direction.

[0063] Thus, in the embodiment of a narrow aisle truck according to the invention shown in FIGS. 3a and 3b, a displacement of the mast 120 in the vertical (z) direction, an inclination or pivoting of the mast 120 in the plane spanned by the x and z directions, as well as a pitching of the mast 120 about the effective axis X130 are possible, so that a large number of possible vibrations or disturbances of the mast 120 with respect to its predefined target state can be compensated for or combated.

[0064] A second embodiment of a narrow aisle truck according to the invention, in which actuators of the type shown in FIG. 2 can also be used, is shown in FIGS. 4a and 4b, denoted there by the reference numeral 200.

[0065] In this second embodiment, the mast 220, analogously to the mast 120 of FIGS. 3a and 3b, is mounted in a floating manner with respect to a bearing plane by means of a bearing arrangement 228 which extends in the x and z directions. Furthermore, a further bearing arrangement 234 is provided, which is implemented by two pivot levers 234a and 234b on both sides of the mast 220 in the x direction, and which allows the mast 220 to pivot about an axis running in the y direction, which is driven by a first actuator 230 oriented in the x direction.

[0066] The configuration of the second bearing arrangement 234 with the aid of the two pivot levers 234a and 234b also forms, in a manner similar to the embodiment of FIGS. 3a and 3b, an effective axis running along the x direction, which is formed by a solely-rotatably mounted shaft 236 connected to the two pivot levers 234a and 234b. This shaft 236 allows a pivoting or a pitching of the mast 220 that can be driven by a second actuator 232 which, in a manner analogous to the embodiment shown in FIGS. 3a and 3b, causes the first bearing arrangement 228 to be displaced in the y direction. Thus, the embodiments of FIGS. 3a and 3b as well as 4a and 4b correspond in terms of the possible degrees of freedom and drivable pivoting movements of the masts 120 and 220, but differ in the design of their respective further bearing arrangements 134 and 234 and the positioning and mode of operation of their actuators 130a and 130b, and 230, respectively.

[0067] FIGS. 5a and 5b show a third embodiment of a narrow aisle truck according to the invention, which is denoted by the reference numeral 300, and which also has significant overlaps with the embodiment 100 of FIGS. 3a and 3b.

[0068] In particular, the two embodiments mentioned follow the same concepts with regard to their first bearing arrangements 128 and 328, and with regard to an actuator 132 and 332 acting thereon in they direction. Likewise, the mast 320 of FIGS. 5a and 5b is also arranged to be floating with respect to a plane running in the x direction and z direction and pivotable about an effective axis X330 with respect to the vehicle body 312. However, in the embodiment 300 shown in FIGS. 5a and 5b, only a single actuator 330 is provided for displacing the mast 320 in the z direction, which actuator can only act on one side thereof.

[0069] On the opposite side of the mast 320 in the z direction, the actuator 330 is opposite a radial spherical plain bearing 331, which both allows the pivoting of the mast 320 about the already mentioned effective axis X330 and itself forms a pivot axis running in the y direction, which allows the pivoting driven by the actuator 330 within the bearing plane. Here, the actuator 330 and the radial spherical plain bearing 331 together form a further bearing arrangement 334. Although in this embodiment the pivot point for the mentioned pivoting lies in the bearing plane outside the mast 320 itself, this does not impair the effectiveness and efficiency of a pivoting movement driven in this way.

[0070] In this embodiment, a further variant is also conceivable in which the bearing arrangement 328 also firmly clamps the mast 320 in the x direction, so that only one degree of freedom in the z direction remains in this variant of the bearing arrangement 328. In this case, a slight elastic deformation of the mast 320 between the two bearing arrangements 328 and 334 would have to be provided and accepted for a pivoting movement about the axis running in the y direction, said axis formed by means of the radial joint bearing 331.

[0071] FIGS. 6a and 6b now show a fourth embodiment 400 of a narrow aisle truck according to the invention, which substantially corresponds to the first embodiment of FIGS. 3a and 3b with regard to its bearing arrangement 428 and to an actuator 432 which displaces it. In contrast to the first embodiment, however, the further bearing arrangement 434 is formed by two bearing elements 434a and 434b which are free in the x direction and are provided on both sides of the mast 420 in the form of cylindrical sliding guide elements, which together form a further bearing arrangement 434, and allow a pitching of the mast 420 about an effective axis X430.

[0072] Although these cylindrical sliding guide elements 434a and 434b can also have a certain amount of play in the z direction, in any case they provide a degree of freedom in the x direction for pivoting the mast 420 about a pivot axis running substantially in the y direction, which possibly requires a torsion of the mast due to it being fixed in the z direction. In order to drive this pivoting, an actuator 430 is again provided, which drives a displacement of the mast 420 in the x direction in the region of the further bearing arrangement 434. In this case, the bearing arrangement 428 can in turn be designed such that it only allows a movement in the z direction of the mast 420, and thus the pivoting movement about the pivot axis running in the y direction is brought about by an elastic bending of the mast 420. This embodiment is characterised by simple and inexpensive bearing arrangements and, due to the relatively strong similarities with narrow aisle trucks that are already in production, further synergy effects can be achieved.

[0073] A fifth embodiment of a narrow aisle truck according to the invention is shown in FIGS. 7a to 7c, and is denoted by the reference numeral 500. This embodiment 500 is characterised in that two actuators 530a and 530b are provided in the region of the bearing arrangement 528, which act on the mast at an angle to one another, and for this purpose are arranged as an isosceles triangle with the width direction of the narrow aisle truck 500.

[0074] In this embodiment, the bearing arrangement 528 allows the mast 520 to move in the x-y plane, and the further bearing arrangement 534 forms a centre of rotation for pivoting the mast 520 about the respective axes—both about the x direction and about the y direction. Because the two actuators 530a and 530b can now be operated in a coordinated manner, vibrations about axes running parallel to the x direction, as well as parallel to the y direction, can be driven in a suitable manner, wherein the degrees of freedom are exactly determined and fewer bearing points are necessary due to the provision of the centre of rotation in the region of the further bearing arrangement 534. Furthermore, the bearings used can be designed to run particularly smoothly, and also a greater level compensation, in particular with regard to a rotation about the x axis, can be easily implemented.

[0075] The embodiment of FIGS. 8a to 8c, which is denoted there by the reference numeral 600, and comprises two variants that are shown in FIGS. 8b and 8c, represents in a certain way a modification of the embodiment 500 of FIGS. 7a to 7c, since a further bearing arrangement 634 is also provided in this case, which allows a centrally placed centre of rotation for pivoting the mast 620 about an axis parallel to the y direction. For this purpose, in the variant of FIG. 8b, an arcuate linear guide 634a is provided as a further bearing arrangement 634, while in the variant of FIG. 8c a slewing ring bearing 634b is used as a further bearing arrangement 634.

[0076] The actuator 630 acting in the x direction can thus in both variants cause a pivoting about the given axis running through the bearing arrangement 634 and in the y direction, while the corresponding bearing points are also designed in such a way that actuating a further actuator 632 oriented in the y direction, which allows a displacement of the bearing arrangement 628, causes a pivoting of the mast about an effective axis X634 running through the bearing point and in the x direction. In this embodiment, too, the degrees of freedom for pivoting the mast are exactly determined, and no additional translation in the z direction is necessary in the bearing points. A smooth-running bearing is thus possible, and greater level compensations, in particular in the case of a rotation about the pivot axis parallel to the y direction, can be easily implemented.

[0077] Finally, a seventh embodiment of a narrow aisle truck according to the invention is shown in FIGS. 9a and 9b, and is denoted by the reference numeral 700. In this embodiment, the bearing arrangement 728 is formed by a slewing ring bearing which is arranged centrally on the underside of the mast 720, in particular with regard to the vertical direction, in the region of the wheels 714a, 714b and 718 of the narrow aisle truck 700. This bearing arrangement 728 allows the mast 720 to be pivoted both about a pivot axis running in the x direction X728 and about a pivot axis Y728 running in the y direction.

[0078] In order to drive the corresponding pivoting movements, an actuator 730 designed as a rotating spindle and, on the other hand, a further actuator 732 designed as a cylinder, which can also move the rotating spindle 730 in the y direction, are provided. The rotating spindle 730 thus drives the pivoting of the mast 720 about the pivot axis Y728 running in the y direction, while the cylinder 732 drives the pivoting of the mast 720 about the pivot axis X728 running in the x direction.

[0079] Finally, it should be pointed out that many of the embodiments discussed above can also be implemented in variants with fewer degrees of freedom; for example, in the embodiments of FIGS. 3a to 6b, each of the bearing arrangements 128, 228, 328 or 428 could be fixed to the corresponding vehicle body 112, 212, 312 or 412, so that the further actuators 132, 232, 332 or 432 and thus the possibility of stimulating the respective mast 120, 220, 320 or 420 to pitching movements, would be dispensed with. It should also be noted that the present invention is not limited to narrow aisle trucks with three wheels, of which only one is driven and steered, but that other configurations are also conceivable, for example with four wheels, two of which are driven and the other two are steered.