Industrial truck and method for operating the same

Abstract

The present invention relates to an industrial truck (10) comprising a vehicle body (12) having a longitudinal direction and a width direction, a lifting mast (20) extending from the vehicle body (12) in a substantially vertical direction, an active position control system (22) which is configured to effect a relative movement of the lifting mast (20) with respect to the vehicle body (12), at least one support element (28) which extends between a first connection point (24) on the vehicle body (12) and a second connection point (26) on the lifting mast (20), and a support element adjustment system (30) which is configured to adjust a length of the support element (28) when the lifting mast (20) moves with respect to the vehicle body (12) in such a way that the resulting relative displacement of the second connection point (26) with respect to the first connection point (24) is compensated.Furthermore, the invention relates to a method for operating such an industrial truck.

Description

[0001] The present invention relates to an industrial truck comprising a vehicle body having a longitudinal direction and a width direction, a mast extending from the vehicle body in a substantially vertical direction, an active position control system configured to effect a relative movement of the mast with respect to the vehicle body, for example to suppress vibrations of the mast or to compensate for deflection of the mast during storage or retrieval of a load, and at least one support element extending between a first connection point on the vehicle body and a second connection point on the mast. The invention further relates to a method for operating such an industrial truck.

[0002] It is known from the prior art, and in particular from DE 10 2020 116 337 A1, for example, to provide active systems in industrial trucks to prevent mast vibrations and to compensate for mast deformations. Such systems typically comprise a detection unit that detects a condition of the vehicle and / or its surroundings. Based on this detection, actuators are operated that cause the vehicle's mast to move relative to the vehicle body, for example, to reactively or proactively suppress mast vibrations.

[0003] It is also known to provide support devices in industrial trucks that extend between a fastening point on a vehicle body of the corresponding vehicle and another fastening point on the mast of such a vehicle in order to provide improved support and power transmission between the mast and the vehicle body. By way of example, reference is made in this context to EP 3 263 510 A1, in which such a support device is provided in an industrial truck, which is further associated with a device for reducing vibrations.

[0004] However, practice has shown that, although a combination of these two systems—an active position control system for the mast and a support element—would be advantageous and desirable in principle to combine the aforementioned advantages of both systems, it also presents the problem that, with a rigid design of such a support device, the mast can also be rotated about a vertical axis when deflected by the active position control system. Such a rigid coupling would therefore, in turn, lead to additional uncontrolled movements of loads carried by the mast.Although a less rigid connection of the mast via a corresponding support element would be advantageous from this point of view, this would mean that the actual purpose of power transmission or connecting the mast to the vehicle body via the two connection points would be less effectively achieved.

[0005] Accordingly, it is desirable to be able to implement a combination of an active position control system and at least one support element in an industrial truck, whereby undesirable interactions between the two components mentioned are to be excluded and consequently an active position control of the mast is to be enabled, while at the same time the mast is optimally supported by at least one support element on the vehicle body.

[0006] To solve this problem and eliminate the aforementioned disadvantages of the prior art, the invention proposes additionally equipping a corresponding generic industrial truck with a support element adjustment system configured to adjust the length of the support element upon movement of the mast relative to the vehicle body in such a way that the resulting relative displacement of the second connection point relative to the first connection point is compensated. In this way, it is possible to dynamically adjust the length of at least one support element in the industrial truck according to the invention, so that optimal stability or an optimal force flow can be maintained at all times and in all states of the mast.In other words, a movement of the second connection point provided on the lifting frame is compensated for by suitably changing the guy length of the at least one support element towards the vehicle body.

[0007] First of all, it should be explained that the term "essentially vertically" aligned mast is to be understood as meaning that a vertical alignment thereof initially exists in an undeflected resting state, thereby enabling optimal handling of loads and the like by means of a height-adjustable load-handling device assigned to the mast. At the same time, however, the active position control system should enable deflection of the mast relative to the vertical with respect to at least one degree of freedom. The position control system can, in particular, be configured to pivot the mast about an axis parallel to the longitudinal direction of the vehicle body.

[0008] Furthermore, it should be noted that the active attitude control system of the vehicle according to the invention can comprise at least one sensor for detecting a state of the vehicle and / or its surroundings, at least one actuator for triggering the relative movement of the lifting mast with respect to the vehicle body, a control unit for processing the data supplied by the at least one sensor unit and for controlling the at least one actuator and, if appropriate, a prediction unit which can be integrated, for example, with the control unit and can be capable of predicting disturbances to be expected in the future from the detected current spatial and movement state of the vehicle as well as knowledge of its surroundings and of proactively controlling the at least one actuator in order to prevent or at least reduce predicted or expected vibrations or other disturbances of the lifting mast.The aforementioned means can also be used to compensate for any deflection of the lifting frame when a load is being loaded or unloaded, provided that such deflection is detected by a suitable sensor.

[0009] In order to further ensure the constant force flow with respect to the at least one support element during all possible operating states of the industrial truck according to the invention, the neutral position of the support element can first be suitably adjusted before commissioning the industrial truck, so that the desired behavior of the support element with regard to the absorption and transmission of forces is achieved in the non-deflected neutral position of the mast. Furthermore, in this way, a deflection of the mast relative to the vehicle body is appropriately compensated by the support element and the support element adjustment system in such a way that the most unchanged force transmission possible and the maintenance of the force flow in all states of the mast can be ensured.

[0010] In principle, different designs of the support element and the support element adaptation system are conceivable in industrial trucks according to the invention in order to be able to achieve the desired properties or the intended functioning thereof.

[0011] In a first conceivable variant, the at least one support element can comprise a rigid first section and a second section whose length is adjustable relative to the first connection point, and the support element adjustment system can comprise a mechanical coupling between the lifting frame and the second section. The term "length-adjustable" second section is to be understood in such a way that, for example, the distance between the end of the first section adjacent to the second section and the first connection point can be achieved by appropriately pivoting a lever, which is to be understood as the second section of the support element, or by providing an eccentric disc. Generally speaking, the second section is thus a component by means of which the length change of the support element between the two connection points can be brought about in a general manner.Another example of this is a so-called "support-integrated" second section, which can be designed as a length-adjustable element provided at any position along the length of the support element, for example by means of a telescopic section, a length-adjustable actuator or the like, in order to be able to adjust the length of the support element at this point away from the two connection points thereof.

[0012] With regard to the aforementioned variant of a mechanical coupling of the support element adjustment system, several specific embodiments are also conceivable. For example, this mechanical coupling can be implemented using a linkage, which, by means of a connection to the lifting frame via a pivoting element, causes the second section of the support element to pivot, thereby changing the length of the support element. Such an embodiment can therefore be formed with a simple and rigid connection between the corresponding pivoting joints or, for example, via a toggle lever with corresponding swivel joints.

[0013] A further embodiment of such a mechanical coupling of the support element adjustment system can be implemented using a Bowden cable, which, by means of a connection to the lifting mast, causes a change in the length of the support element when the lifting mast moves relative to the vehicle body. In such an embodiment, the length-adjustable second section of the support element is designed such that the force transmission via the Bowden cable allows both a shortening and an extension thereof, in order to be able to convert any movement of the lifting mast relative to the vehicle body into an extension or shortening of the support element in a suitable manner.

[0014] Furthermore, it is also conceivable to implement the mechanical coupling of the support element adjustment system by means of a cardan shaft, a spindle drive, a chain drive, or a belt drive. A connection to the lifting mast triggers a rotary movement of the corresponding drive when the lifting mast moves relative to the vehicle body, which causes the second section of the support element to pivot, resulting in a change in the length of the support element. Depending on the specific design, the corresponding second section of the support element can be designed, for example, as an eccentric disc or as a joint or hinge with suitable leverage ratios in order to convert the rotary movement transmitted by the respective drive into a corresponding change in the length of the second section of the support element.

[0015] Furthermore, the mechanical coupling of the support element adjustment system could also be implemented by means of a rack, by means of which a movement of the lifting frame relative to the vehicle body is converted into a change in the length of the second section of the support element. In this case, a substantially parallel movement of the second section of the support element can be achieved compared to the deflection of the lifting frame relative to the vehicle body, whereby suitable leverage ratios can again be provided between the support element and the lifting frame, for example, to enable different angles of the support elements relative to the vehicle body.

[0016] As an alternative to the variant with a mechanical coupling, the support element adjustment system could also comprise a hydraulic coupling between the lifting mast and the support element, wherein a receiving element is assigned to the lifting mast and a length-adjustable master element is assigned to the support element, and a movement of the lifting mast relative to the vehicle body is converted into a change in the length of the support element. In this case, a corresponding master element could, for example, be designed directly as a master cylinder, which could act as a length-adjustable second section of the support element. However, a more complex design could also be provided, in which, for example, a telescopic change in the length of the support element is provided, and the corresponding master element then drives a corresponding extension and retraction movement of the telescopic system.

[0017] A similar, for example, direct or telescopic, change in the length of the support element could further be achieved by the support element adjustment system comprising an electronic coupling between the lifting mast and the support element, wherein a detection unit is assigned to the lifting mast and a length-adjustable actuating unit is assigned to the support element. A movement of the lifting mast relative to the vehicle body is detected by a control unit of the support element adjustment system using the detection unit, and a change in the length of the actuating unit is effected on this basis. In this case, the detection unit could also be directly integrated with the active position control system, so that a corresponding control of the actuating unit can be coordinated with a control of the at least one actuator of the position control system.Accordingly, the expected deflections of the mast caused by the actuation of the position control system must be evaluated and applied directly to the actuator to enable appropriate interaction between the two systems. In this context, the corresponding actuator could be designed in a conventional manner as an electromechanical actuator, for example, as a linear drive or rotary actuator with a suitable gear unit for translating into a linear movement, which corresponds to a change in the length of the actuator and can thus cause the length of the support element to be adjusted.

[0018] Although it is also conceivable in principle to provide only a single support element on the industrial truck according to the invention, which extends between the mentioned first and second connection points on the vehicle body and the lifting frame, it can be advantageous for improved force absorption with respect to the width direction of the industrial truck if a plurality of support elements are provided, for example two support elements whose respective second connection points are spaced apart from one another in the width direction of the industrial truck.Of course, the first connection points can also be spaced apart from one another in a similar way in the width direction of the mast, whereby the specific positioning of the individual connection points can be made dependent on the overall geometry of the corresponding industrial truck and can, for example, be based on both the width of the vehicle body and the mast.

[0019] Furthermore, the industrial truck according to the invention can be designed, in particular, as a narrow-aisle forklift truck, and a vertically displaceable driver's position support can be assigned to the mast, so that the corresponding vehicle can be designed as a so-called "man-up vehicle." Especially in such vehicle types, it has been shown that vibrations of the mast can significantly impair operating efficiency and driver comfort, since, especially when the load handling device or driver's position support is fully extended, the prevailing leverage conditions can cause significant deflection relative to the ground and considerable acceleration.

[0020] According to a second aspect, the present invention further relates to a method for operating such an industrial truck, comprising detecting vibrations of the mast and / or a deflection of the mast by means of at least one sensor unit of the position control system and / or predicting vibrations of the mast by means of a prediction unit of the position control system, controlling at least one actuator of the position control system to suppress the detected and / or predicted vibrations or to compensate for the detected deflection of the mast by causing a movement of the mast relative to the vehicle body and adjusting the length of the at least one support element such that the resulting relative displacement of the second connection point relative to the first connection point of the at least one support element is compensated.

[0021] Further advantages and features of the present invention will become even clearer from the following description of possible embodiments thereof, when considered together with the accompanying figures. These show in detail: Figure 1: A schematic side view of an embodiment of an industrial truck according to the invention, which can be combined with various variants of support element adjustment systems, which are shown in the following figures; Figures 2a to 2g: concrete embodiments of support element adjustment systems with mechanical coupling; Figures 3a and 3b: embodiments of support element adjustment systems with mechanical coupling and support-integrated length change; Figure 4: an embodiment of a support element adjustment system with hydraulic coupling; Figure 5: an embodiment of a support element adjustment system with electronic coupling; and Figure 6: a detailed view of a variant of the support element adjustment system from Figure 2d .

[0022] In Figure 1First, an industrial truck according to the invention is shown schematically in a side view. The industrial truck is generally designated by the reference numeral 10 and is designed as a narrow-aisle forklift truck. It comprises a vehicle body 12 with a front pair of wheels 14, which are provided on respective longitudinal members 16, and a driven and steered rear wheel 18, with which the vehicle 10 rests on a driving surface U.

[0023] The axes of rotation of the front wheels 14 and the rear wheel 18 each run in the width direction of the vehicle 10, while the straight-ahead direction of travel of the vehicle 10 is also referred to as the longitudinal direction. Between the two axes of the front wheels 14 and the rear wheel 18 in the longitudinal direction of the vehicle 10, a lifting frame 20 extends in a substantially vertical direction, with which in the Figure 1shown embodiment, a driver's station 20a is connected in a vertically displaceable manner.

[0024] Due to its design with the mast 20 arranged between the axles of the front wheels 14 and the rear wheel 18, the industrial truck 10 shown here is primarily suitable for use in logistics facilities that have only narrow aisles between high-bay racks, in which goods can be stored and picked by an operator located in the driver's cab 20a. It is understood that in alternative variants, the industrial truck 10 could also be designed with a driver's cab permanently attached to the vehicle body 12 or as a driverless vehicle and could therefore be operated autonomously or remotely. In such variants, the driver's cab would be replaced by a corresponding superstructure.Furthermore, it is understood that the vehicle 10 may include numerous other components which are conventional for such vehicles, for example a hydraulic system which may supply some of the actuators described below.

[0025] Furthermore, the vehicle 10 comprises an active position control system 22, shown only schematically, which is configured to effect a relative movement of the mast 20 relative to the vehicle body 12 to suppress vibrations of the mast 20 and / or to compensate for deflection of the mast 20 during storage or retrieval of a load. For this purpose, the position control system 22 can comprise components not shown in detail here, such as sensor units, actuator units, a controller, and a prediction unit, which, in a manner known per se, evaluate a current state of the vehicle and / or its surroundings and trigger corresponding relative movements of the mast 20 relative to the vehicle body 12 to suppress vibrations of the mast 20.

[0026] Furthermore, the vehicle comprises a support element 28, which extends between a first connection point 24 on the vehicle body 12 and a second connection point 26 on the lifting frame 20 in the form of a guying and serves to transmit forces between the lifting frame 20 and the vehicle body 12 and thus to support the lifting frame 20. It should be noted that, although in Figure 1 only a single support element 28 is shown, but variants of vehicles 10 according to the invention with two or more support elements 28 are also conceivable, which can be designed and / or operated in an identical manner.

[0027] In order to be able to compensate for the changing distance between the connection points 24 and 26 in the event of a relative movement of the mast 20 with respect to the vehicle body 12, which is triggered by the active position control system 22, the industrial truck further comprises a Figure 1 First of all, a support element adjustment system 30 is shown only schematically, which is designed to adjust the length of the support element 24 when the lifting frame 20 moves relative to the vehicle body 12. Different configurations of this support element adjustment system 30 are conceivable, which are explained below with reference to the other figures.

[0028] These illustrate respective embodiments of vehicles according to the invention, which differ essentially in the respective configurations of their support element adaptation systems. Therefore, in order to avoid unnecessary duplication of explanations of some identical or equivalent components, these are each designated by the same reference numerals, each increased by a multiple of 100, and reference is made to their general description within the framework of the generic embodiment of Figure 1For example, the corresponding lifting frames are designated 120, 220, 320, ..., while the vehicle bodies are designated 112, 212, 312, ... and a description of them is omitted. Figures 2a to 2g , 3a and 3b each variant of support element adaptation systems with mechanical coupling between the lifting frame 20 and the support element 28 of the vehicle 10 from Figure 1 . In all figures described below, arrows are used to illustrate the corresponding movements of the individual components when the respective lifting mast moves.

[0029] A first example of this is in Figure 2ashown and designated by the reference numeral 100, wherein the support element 128 comprises a first section 128a and a second section 128b and the change in length of the support element 128 is accomplished only by the second section 128b, which is designed as a rotatable element which, depending on the angular position, can compensate for a different distance between the first connection point 124 and the second connection point 126 of the support element 128.

[0030] For this purpose, the support element adjustment system 100 further comprises a linkage 130, which can convert a translation of a relative movement of the lifting frame 120 with respect to the vehicle body 112 into a corresponding pivoting movement of the second section 128b of the support element 128 in order to adapt its length in a suitable manner to the deflection of the lifting frame 120. Thus, in each deflection state of the lifting frame 120, a correct length of the support element 128 is ensured, wherein the respective design of the lever ratios of the second section 128b of the support element 128 and of the linkage 130 can be adapted to the specific geometric conditions of the vehicle 10 and the specific movements of the linkage 130 and of the second section 128b of the support element 128 can be determined by the Figure 2a can be traced using the arrows shown.

[0031] Similarly, in Figure 2bAn embodiment is shown in which a toggle lever 230 is provided in the support element adjustment system 200, which can also cause a pivoting of the second section 228b of the support element 228 and thus a change in its length. This variant is characterized by the fact that only swivel joints and simple components are required, although complete freedom from tension of the joints cannot be achieved, and the coupling rod used must be adjustable.

[0032] Another variant is also in Figure 2cshown, in which an arrangement of Bowden cables 330 is used together with a corresponding second section 328b of the support element 328, which, according to a counter element 330a assigned to the lifting frame 320, can be changed in length in both directions based on the effects of the Bowden cables 330, that is to say can be both lengthened and shortened, in order to be able to compensate for all corresponding movements of the lifting frame 320 relative to the vehicle body 312.

[0033] Another variant of a support element adjustment system 400 is shown in Figure 2d shown, in which a cardan shaft 430 is provided, which in a similar manner as in the Figures 2a and 2bIn the embodiments shown, this causes the second section 428b of the support element 428 to twist to change its length when the lifting frame 420 is deflected. This shows that in this embodiment, a high level of power transmission and a virtually rigid connection is possible through the provided cardan shaft 430, and furthermore, great flexibility is achieved with regard to its length. However, this solution is structurally relatively complex, since intermediate bearings are necessary and increased space is required. Furthermore, input and output gears are required in order to convert the initially linear movement of the lifting frame 420 relative to the vehicle body 412 into a rotary movement, which is then converted back into a pivoting movement of the second section 428b of the support element 428.

[0034] Another variant is in Figure 2eshown, in which a spindle drive 530 is used in a support element adjustment system 500. In contrast to the embodiment with a cardan shaft 430 from Figure 2d A completely rigid connection can be used, and the corresponding spindle drive can be designed to be self-locking. Although high power transmission is also possible in this embodiment, a precise bearing of the spindle drive shaft 530 is necessary, and increased manufacturing costs are to be expected in this variant.

[0035] Figure 2fnow shows an embodiment with a chain or belt drive, in which the mechanical coupling of the support element adjustment system 600 is achieved by coupling the lifting frame 620 to a rotating disk of the chain or belt drive 630 and the second section 628b of the support element 628 is designed as an eccentric disk, which leads to a change in the length of the support element 628 as a whole when rotated by the chain or belt drive 630.

[0036] Another variant with mechanical coupling is in Figure 2gas a support element adjustment system 700 with a rack and pinion unit 730, which can directly translate a movement of the lifting frame 720 relative to the vehicle body 712 into a parallel movement of the second section 728b of the support element 728 to a corresponding displacement element on the lifting frame 720. This variant also represents a nearly rigid connection and the possibility for high power transmission, but requires precise bearing of the corresponding shaft.

[0037] The Figures 3a and 3bnow show two variants 800 and 900 of support element adaptation systems in which the length variability of the support elements 828 and 928 is implemented in a "support-integrated" manner, i.e. the length-variable second section 828b or 928b of the support elements 828 and 928 is not arranged directly in the region of the first connection points 824, 924, but in a section remote therefrom relative to the length of the support element 828 or 928. Thus, in these two variants, the corresponding first section 828a or 928a is each designed in two parts and extends on both sides of the respective second section 828b or 928b.

[0038] In variant 800, a mechanical coupling 830 is provided, which first converts a movement of the lifting frame 820 into a rotary movement of a shaft, which is then converted again into a linear movement in the region of the support element 828, enabling a telescoping of the support element 828 in the region of the second section 828b. In contrast, in variant 900, a mechanical coupling 930 is used, which, in a guided manner via a lever mechanism, converts a movement of the lifting frame 920 relative to the vehicle body 912 into a telescoping movement of the support element 928 by means of a forward and backward movement of a shaft.

[0039] In contrast to the previously discussed variants with mechanical coupling, the Figure 4Now, a variant of a support element adjustment system 1000 with a hydraulic coupling, in which a hydraulic slave cylinder 1030 is assigned to the lifting frame 1020, while a master cylinder 1032 acting as a length-adjustable second section 1028b is assigned to the support element 1028. By appropriately designing the two cylinders 1030 and 1032, a geometric relationship can be established which, upon deflection of the lifting frame 1020 relative to the vehicle body 1012, causes a corresponding lengthening or shortening of the support element 1028. In particular, the slave cylinder 1030 can hydraulically transmit the movement of the lifting frame 1020 in the same direction to the master cylinder 1032 and the respective hydraulic volume of the two cylinders 1030 and 1032 can be adapted to the inclination of the support element 1028 relative to the vehicle body 1012.

[0040] Similarly, in Figure 5an electronic support element adjustment system 1100 is shown, in which an electronic coupling is provided between the lifting mast 1120 and the support element 1128, wherein a detection unit 1130 is assigned to the lifting mast 1120 and a length-adjustable actuating unit 1132 is assigned to the support element 1128, and a movement of the lifting mast 1120 relative to the vehicle body 1112 is detected by a control unit 1134 of the support element adjustment system 1100 and, on this basis, a change in the length of the actuating unit 1132 is effected. In this case, the actuating unit 1132 can act directly as a length-adjustable second section 1128b of the support element 1128 or, for example, drive a telescopic section of the support element 1128 to extend and retract. Furthermore, it should be noted that the detection unit 1130 orits control unit 1134 can also be directly integrated with the control unit of the position control system 1122 (not shown in more detail), and the control of the actuating unit 1132 can be coordinated with the control of the at least one actuator of the position control system 1122 on the basis of acquired data about a state of the vehicle 10 or its surroundings.

[0041] Finally, the Figure 6 a detailed view of the variants Figure 2d, whereby it becomes clear at this point that the cardan shaft 430 acts on an eccentric wheel 432, which in turn carries the first section 428a of the support element 428 and, by rotating, displaces the eccentric wheel into a position corresponding to a different length of the corresponding support element 428 in order to compensate for the movement of the lifting frame 420, which initially triggered the rotation of the cardan shaft 430. Thus, in this variant, the eccentric wheel 432 corresponds precisely to the length-adjustable second section 428b of the support element 428.

Claims

1. Industrial truck (10), comprising: - a vehicle body (12) with a longitudinal direction and a width direction; - a lifting mast (20) extending from the vehicle body (12) in a substantially vertical direction; - an active position control system (22) configured to effect a relative movement of the lifting mast (20) relative to the vehicle body (12); - at least one support element (28) extending between a first connection point (24) on the vehicle body (12) and a second connection point (26) on the lifting mast (20); and - a support element adjustment system (30) configured to adjust a length of the support element (28) upon movement of the lifting mast (20) relative to the vehicle body (12) such that the resulting relative displacement of the second connection point (26) relative to the first connection point (24) is compensated. ​2. Industrial truck (10) according to claim 1, wherein the position control system (22) is configured to pivot the lifting frame (20) about an axis parallel to the longitudinal direction of the vehicle body (12).

3. Industrial truck (10) according to one of claims 1 and 2, wherein the at least one support element (128, 828, 928) comprises a rigid first section (128a, 828a, 928a) and a second section (128b, 828b, 928b) whose length is variable with respect to the first connection point (124, 824, 924), and the support element adjustment system (100, 800, 900) comprises a mechanical coupling between the mast (120, 820, 920) and the second section (128b, 828b, 928b).

4. Industrial truck (10) according to claim 3, wherein the mechanical coupling of the support element adjustment system (100, 200) is implemented by means of a linkage (130, 230) which, by means of a connection to the mast (120, 220) via a pivotable element, causes pivoting of the second section (128b, 228b) of the support element (128, 228) to change the length of the support element (128, 228).

5. Industrial truck (10) according to claim 3, wherein the mechanical coupling of the support element adjustment system (300) is implemented by means of a Bowden cable (330), which, by means of a connection to the lifting frame (320), causes a change in the length of the support element (328) upon movement of the lifting frame (320) relative to the vehicle body (312). ​6. Industrial truck (10) according to claim 3, wherein the mechanical coupling of the support element adjustment system (400; 500; 600) is implemented by means of a cardan shaft (430), a spindle drive (530), a chain drive or a belt drive (630), wherein a connection to the lifting frame (420; 520; 620) triggers a rotational movement of the corresponding drive (430; 530; 630) upon movement of the lifting frame (420; 520; 620) relative to the vehicle body (412; 512; 612), which rotational movement causes the second section (428b; 528b; 628b) of the support element (428; 528; 628) to pivot, resulting in a change in the length of the support element (428; 528; 628). causes.

7. Industrial truck (10) according to claim 3, wherein the mechanical coupling of the support element adjustment system (700) is implemented by means of a rack, by means of which a movement of the lifting frame (720) relative to the vehicle body (712) is converted into a change in the length of the second section (728b) of the support element (728).

8. Industrial truck (10) according to one of claims 1 and 2, wherein the support element adjustment system (1000) comprises a hydraulic coupling between the lifting frame (1020) and the support element (1028), wherein a receiving element (1030) is assigned to the lifting frame (1028) and a length-adjustable transmitter element (1032) is assigned to the support element (1028), and a movement of the lifting frame (1020) relative to the vehicle body (1012) is converted into a change in the length of the support element (1028). ​9. Industrial truck (10) according to one of claims 1 and 2, wherein the support element adjustment system comprises an electronic coupling (1130) between the lifting mast (1120) and the support element (1128), wherein a detection unit (1130) is assigned to the lifting mast (1120) and a length-adjustable actuating unit (1132) is assigned to the support element (1128), and a movement of the lifting mast (1120) relative to the vehicle body (1112) is detected by a control unit (1134) of the support element adjustment system, and on this basis, a change in the length of the actuating unit (1132) is effected.

10. Industrial truck (10) according to one of the preceding claims, comprising a plurality of support elements (28), the respective second connection points (26) of which are preferably spaced apart from one another in the width direction of the industrial truck (10). ​11. Industrial truck (10) according to one of the preceding claims, wherein the industrial truck (10) is designed as a narrow-aisle forklift truck and a vertically displaceable driver's seat support (20a) is assigned to the lifting frame (20). ​12. A method for operating an industrial truck (10) according to one of the preceding claims, comprising: - detecting vibrations of the mast (20) and / or deflection of the mast (20) by means of at least one sensor unit of the position control system (22) and / or predicting vibrations of the mast (20) by means of a prediction unit of the position control system (22); - controlling at least one actuator of the position control system (22) to suppress the detected and / or predicted vibrations or to compensate for the detected deflection of the mast (20) by causing a movement of the mast (20) relative to the vehicle body (12); and - adjusting the length of the at least one support element (28) such that the resulting relative displacement of the second connection point (26) relative to the first connection point (24) of the at least one support element (28) is compensated.

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