Support Roller, Vehicle with A Support Roller and Method for Stabilizing A Vehicle

Abstract

A support roller (30, 30) for supporting a vehicle on an underlying surface, comprising at least one bearing element which is at least indirectly connectable to at least one supporting structure of the vehicle, at least one fork connected to the bearing element, and at least one wheel (90, 90) which is mounted in the fork so as to be rotatable about a first rolling axis (R) and can be brought into contact with the underlying surface, at least one sensing device (190) for sensing at least one supporting force with which the wheel (90, 90) is supported on the underlying surface. A vehicle, in particular an industrial truck, comprising at least one support roller and a method for stabilizing a vehicle.

Claims

1. A support roller (30, 30) for supporting a vehicle on an underlying surface, comprising at least one bearing element which is at least indirectly connectable to at least one supporting structure of the vehicle, at least one fork connected to the bearing element, and at least one wheel (90, 90) which is mounted in the fork so as to be rotatable about a first rolling axis (R) and can be brought into contact with the underlying surface, wherein the support roller further comprises at least one sensing device (190) for sensing at least one supporting force with which the wheel (90, 90) is supported on the underlying surface, and wherein a force acting between at least a first element and at least a second element is detectable by means of the sensing means.

2. The support roller (30, 30) according to claim 1, characterized in that (i) the rolling axis (R) is perpendicular to a normal direction (N) of the underlying surface and/or that the supporting structure is formed at least in certain areas by a part of the vehicle body; (ii) the bearing element is formed in the form of at least one rotary bearing (110, 110) and that a rotation of the fork about a pivot axis (S) running substantially perpendicularly to the rolling axis (R) is possible by means of the rotary bearing (110, 110), wherein in particular the rolling axis (R) and the pivot axis (S) intersect or run obliquely relative to one another and/or the fork and/or the rolling axis (R) can be forced by means of at least one first return device into at least one predetermined position relative to the bearing element and/or the supporting structure, preferably with regard to the pivot axis (S), and/or, (iii) that a movement of at least one first element relative to at least one second element is detectable by means of the sensing device (190), preferably that a, in particular linear, movement in a first direction running perpendicularly to the rolling axis (R) and/or parallel to the pivot axis (S), and/or a force acting by means of the sensing device (190) a tensile force, a compressive force and/or shear force is detectable.

3. (canceled)

4. (canceled)

5. The support roller (30, 30) according to claim 1, characterized in that (a) that the first element is selected from the group comprising the roller, a bearing axle of the roller mounted in the fork, the fork, at least one connecting means of the fork to the bearing element, such as a pin (114), and the bearing element, and/or the second element is selected from the group comprising the bearing axle, the fork, the connecting means, the bearing element and the supporting structure, (b) the second element, in particular the bearing element, is adapted to keep the first element, in particular the fork, movable along the first direction (X), preferably the second element (110, 110) is adapted to allow a movement of the first element of up to 5 mm, in particular of 3 mm, preferably relative to the second element, and/or (c) the first element, in particular the fork and/or the connecting means, is forcible into a first position, in particular in a direction (X) towards the second element, by means of at least one second return device.

6. (canceled)

7. (canceled)

8. The support roller (30, 30) according to claim 2, characterized in that the first return device and/or the second return device comprises at least one elastic means (170), at least one compression spring, at least one helical spring, at least one pneumatic spring, at least one hydraulic spring and/or at least one gas pressure spring, and/or the sensing device (190) is arranged at least in certain areas in the bearing element and/or on the side of the bearing element, preferably the pivot bearing (110, 110), facing away from the fork and/or the wheel (90, 90).

9. (canceled)

10. The support roller (30, 30) according to claim 1, characterized by at least one position recognition device by means of which an alignment of the fork, the bearing axis and/or the wheel (90, 90) about the pivot axis (S) and/or relative to the underlying surface is determinable.

11. The support roller (30, 30) according to claim 1, characterized in that the sensing device (190) and/or the position recognition device comprises and/or comprise at least one sensor means, in particular comprising at least one limit switch, at least one strain gauge sensor, at least one pressure sensor, at least one Hall sensor, at least one radar sensor, at least one ultrasonic sensor, at least one distance sensor, at least one echo sounder sensor, at least one acoustic sensor, at least one optical sensor, at least one electromagnetic sensor, and/or at least one magnetic sensor, or and/or the first position and/or at least a second position of the first element relative to the second element is detectable by means of the sensing device (190).

12. A vehicle, in particular an industrial truck, comprising at least one support roller (30, 30) according to claim 1.

13. The vehicle according to claim 12, characterized in that the vehicle further comprises at least one coupling rocker (210), wherein the coupling rocker (210) is arranged mechanically between the supporting structure and the support roller (30, 30) and the coupling rocker (210) has at least one rocker (214) mounted rotatably about at least one rotary axis (D) and a lever (216, 216) which is operatively connected to the rocker (214), wherein the support roller (30, 30), in particular the bearing element, is supported at the end of the lever (216, 216) away from the pivot axis (S) and/or the rocker (214), wherein furthermore the lever (216, 216) is preferably surrounded by the rocker (214) and/or is formed integrally with the rocker (214) at least in certain areas, wherein the coupling rocker (210) comprises at least one third return device by means of which the rocker (214) and/or the lever (216, 216) is/are forcible into at least one third position, wherein the third return device preferably comprises at least one torsion spring, at least one helical spring, at least one tension spring, at least one thrust spring, at least one shear spring, at least one rubber-elastic element, at least one spiral spring and/or at least one gas pressure spring.

14. (canceled)

15. The vehicle according to claim 13, characterized in that (i) the coupling rocker (210) comprises at least one shock absorbing device, wherein a movement, in particular of the lever (216, 2161 the support roller (30, 30) and/or the rocker (214) about the rotary axis (D) can be cushioned by means of the shock absorbing device, and/or (ii) the vehicle is characterized by at least one control member, which is in particular in operative connection with the shock absorbing device, wherein a movement, in particular of the lever (216, 2161 the support roller (30, 30) and/or the rocker (214), about the rotary axis (D) by means of the control member is reducible, preferably suppressible, wherein the control member is preferably at least in certain areas enclosed by the shock absorbing device.

16. (canceled)

17. The vehicle according to claim 15 or 16, characterized in that the shock absorbing device and/or the control member comprises at least one cylinder, in particular a hydraulic cylinder (250), with at least one piston (252) movable within the cylinder, the cylinder being operatively connected to the lever (216, 216), the support roller (30, 30), in particular the bearing element, and/or the rocker (214), preferably via a connecting element (230) extending at least in a radial direction with respect to the rotary axis (D), and the piston (252) being operatively connected to the supporting structure or the piston (252) being operatively connected to the lever (216, 216), the rocker (214), the support roller (30, 30), the bearing element and/or the connecting element (230) and the cylinder being operatively connected to the supporting structure.

18. The vehicle according to claim 17, characterized in that the control member comprises at least one control element, the control element preferably comprises at least one control valve and/or, by means of closing the control element, a movement of the shock absorbing device and/or of the control member and/or a movement, in particular of the rocker (214), of the lever (216), 216) and/or the support roller (30, 30), about the rotary axis is prevented and, when the control element is opened, a movement of the shock absorbing device and/or of the control member and/or a movement, in particular of the rocker (214), of the lever (216, 216) and/or of the support roller (30, 30), about the rotary axis (D) is released.

19. The vehicle according to claim 18, characterized in that (i) the cylinder preferably comprises a single-acting cylinder and the control element comprises a throttle element (258) adapted to control the flow rate of at least one fluid, preferably a hydraulic fluid, a gas and/or air into the cylinder, preferably to allow shock absorbing, preferably the control element being adapted to control the throttle element (258) as a function of the supporting force detected by the sensing device in order to increase the fluid pressure in order to avoid a reduction of the supporting force below a predetermined value, or (ii) the cylinder, in particular the hydraulic cylinder (250), comprises at least two-cylinder chambers (254, 256) connectable to each other via at least one throttle, the fluid being movable in particular between the cylinder chambers (254, 256), in particular by movement of the piston (252).

20. (canceled)

21. The vehicle according to claim 15, characterized in that the control member comprises at least one braking means (262), in particular an electromagnetic brake, a mechanical brake, an adhesive and/or positive brake, the braking means being operatively connected, preferably on the one hand, to the rocker (214) and/or to the support roller (30, 30) and/or, on the other hand, to the supporting structure, wherein (a) the braking means (262) is arranged at least in certain areas, preferably circularly revolving about the rotary axis (D) of the coupling rocker (210), and/or (b) the vehicle is characterized by at least one control device operatively connected to the control member and/or the shock absorbing device, the control device comprising at least one power supply, in particular an electrical voltage supply and/or a device for storing and/or emitting mechanical energy, of the braking means (262), and wherein when energy is emitted from the control device to the control member a movement of the shock absorbing device and/or of the control member and/or a movement, in particular of the rocker (214) and/or of the support roller (30, 30), about the rotary axis (D) is prevented, and when the emission of energy is interrupted a movement of the shock absorbing device and/or of the control member and/or a movement, in particular of the rocker (214) and/or of the support roller (30, 301 about the rotary axis (D) is enabled.

22. (canceled)

23. (canceled)

24. The vehicle according to claim 12, characterized by at least one control device operatively connected to the sensing device (190), the position recognition device, the control device and/or the control member, preferably the control element, wherein the control member can preferably be influenced by means of the control device in such a way that the movement about the rotary axis (D) is reduced, is preferably prevented when, by means of the sensing device (190), a supporting force is sensed which corresponds to a missing contact between the support roller (30, 30) and the underlying surface and/or the movement about the rotary axis (D) is at least partially released when, by means of the sensing device (190), a supporting force is sensed which corresponds to an existing contact between the support roller (30, 30) and the underlying surface, wherein the control device influences the control member as a function of a position of at least one lifting fork of the vehicle, in particular relative to the underlying surface, a speed of the vehicle and/or a steering angle of the vehicle.

25. (canceled)

26. The vehicle according to claim 12, characterized in that (i) the control member comprises at least one pump means for increasing a fluid pressure in the cylinder, in particular the cylinder chambers (254, 256), preferably the control device being adapted to control the pump means as a function of the supporting force detected by the sensing device (190) in order to increase the fluid pressure in order to avoid a reduction of the supporting force below a predetermined value, (ii) the vehicle is characterized by a plurality of support rollers (30, 30) according to any of claims 1 to 11, wherein the coupling rocker (210) preferably comprises a plurality of levers (216, 216), preferably arranged on the rocker (214), surrounded by the rocker (214) and/or at least in certain areas integrally formed with the rocker (214), and/or (iii) the vehicle is formed as an industrial truck and/or as a pallet truck with at least one drive wheel, in particular a pallet truck with five-wheel chassis.

27. (canceled)

28. (canceled)

29. A method (1000) for stabilizing a vehicle according to claim 12, having a coupling rocker (210) and at least one support roller (30, 30) according to claim 1, having the following steps: detecting 1010 a supporting force with which the support roller (30, 30) is supported on an underlying surface, wherein in the case of at least one first supporting force the support roller (30, 30) is in contact with the underlying surface, and in the case of at least one second supporting force the support roller (30, 30) is not in contact with the underlying surface; and controlling (1020) of a control member (250) as a function of the detected supporting force, wherein a rotation of the coupling rocker (210) and/or the support roller (30, 30) about a rotary axis (D) is at least partially prevented by means of the control member upon detecting the second supporting force.

30. The method (1000) according to claim 29, characterized in that, (a) when the first supporting force is recognized, a movement about the rotary axis (D) is cushioned by means of at least one shock absorbing device, (b) the cushioning and suppression of the movement about the rotary axis (D) is carried out by means of a device which at least in part comprises the control member and the shock absorbing device, in particular the shock absorbing device and the control member are at least in part formed integrally, and/or (c) the suppression of the movement about the rotary axis (D) is achieved by suppressing a movement of the shock absorbing device and/or at least a third return device.

31. (canceled)

32. (canceled)

Description

[0048] Further features and advantages of the invention result from the following description, in which preferred embodiments of the invention are explained by means of schematic drawings.

[0049] The following applies:

[0050] FIG. 1a, 1b are schematic front views of a prior art industrial truck in a neutral and inclined vehicle position;

[0051] FIG. 2 is a schematic cross-sectional view of a support roller known from prior art;

[0052] FIG. 3a, 3b are schematic cross-sectional views of a support roller according to an embodiment of the invention in an unloaded and a loaded state;

[0053] FIG. 4 is a schematic view of a coupling rocker with a first and a second support roller and a hydraulic cylinder according to an embodiment of the invention;

[0054] FIG. 5a, 5b are hydraulic circuit diagrams for controlling the hydraulic cylinder according to embodiments of the invention;

[0055] FIG. 6 is a schematic view of a coupling rocker with a first and a second support roller and a braking means according to an embodiment of the invention;

[0056] FIG. 7 is a circuit diagram for the electrical control of the hydraulic valve according to embodiments the invention; and

[0057] FIG. 8 is a flowchart visualizing the execution of a method for stabilizing an industrial truck according to an embodiment of the invention.

[0058] FIG. 1a shows a schematic front view of a vehicle in the form of an industrial truck 1 known from prior art. The industrial truck 1 shown as an example is a pallet truck with a five-wheel chassis, wherein in FIG. 1a only the first and second support rollers 3, 3 and the drive wheel 5, each connected to a supporting structure 4 of the industrial truck 1, are shown. On the industrial truck 1 shown in FIG. 1a, the drive wheel 5 is essentially centered between the first and second support rollers 3, 3. The first and second support rollers 3, 3 are attached to a coupling rocker (not shown) and are connected to each other by this coupling rocker. In the prior art the coupling rocker is usually attached to the support structure of the industrial truck 1 with spring bearings and has the object of distributing the supporting force evenly between the first and second support rollers 3, 3 according to the driving situation.

[0059] FIG. 1b shows a schematic view of the industrial truck 1 shown in FIG. 1a in an inclined position. Industrial truck 1 can, for example, incline accordingly when cornering tightly with loads held in a high position. If the industrial truck 1 tilts to the side, the coupling rocker is rotated about a rotary axis and the entire spring force of the coupling rocker acts on the first support roller 3 in the example shown. The second support roller 3 is relieved accordingly and loses contact with an underlying surface 6 on which the industrial truck 1 is moved (shown in FIG. 1b with a dashed border). If the industrial truck 1 tilts further at this point, and if in particular the support roller 3 moves further in the normal direction N of the underlying surface 6, there is a risk of tipping over. In this situation shown in FIG. 1b, the supporting force with which the support roller 3 is supported on the underlying surface 6 is below a first threshold value, since the support roller 3 does not touch the underlying surface 6, i.e. the support roller 3 is free in the air.

[0060] On the other hand, the supporting force of the support roller 3 is above a threshold value because the support roller 3 is in contact with the underlying surface 6.

[0061] FIG. 2 shows a schematic cross-sectional view of a support roller 3 known from prior art. The support roller 3 comprises a fork which is intended to house a wheel 9. Wheel 9 is held in the fork so that it can rotate about a rolling axis R. By means of a bearing formed as a rotary bearing 11 the fork formed as a steering fork 7 can be held with a wheel on the supporting structure of the industrial truck (not shown) by means of the coupling rocker (not shown) so that it can rotate about a pivot axis S around its own axis. In the support roller 3 shown, two ball bearings 13a, 13b are arranged around the pin 14 of the fork 7 for this purpose. Wheel 9 is attached to the coupling rocker (not shown) via the rotary bearing 11, so that wheel 9 can steer too when cornering.

[0062] FIG. 3a shows a schematic cross-sectional view of a support roller according to an embodiment of the invention in an unloaded state. This means that the supporting force is below the first threshold value, i.e. the support roller 30 in particular is not in contact with the underlying surface. As shown in FIG. 3a, many features of the support roller 30 correspond to the features of the support roller of the prior art shown in FIG. 2. In contrast to the support roller of the prior art, in the embodiment shown the wheel 90 is not only rotatable about the pivot axis S via the steering fork 70 but is also arranged in the rotary bearing 110 along the first direction X, i.e. axially movable to the pivot axis S. In order to achieve improved tracking accuracy, the steering fork 70 can be pulled into a predetermined position around the pivot axis S by means of an unrepresented first return device. For this purpose, in the embodiment shown, plain bearings 150a and 150b are pressed between the ball bearings 130a and 130b and the pin 114 of the steering fork 70. The plain bearing bushes 150a, 150b allow this movement of the wheel 90 along the direction X. FIG. 3a further shows that a second return device, which is formed as an elastic means 170 in the shape of a spring, is arranged at a sliding bush 150 in order to keep the wheel 90 in an unloaded state vertically pushed out relative to the rotary bearing 110. The person skilled in the art knows, however, that the displacement can also be effected by means of other return devices, e.g. a rubber spring.

[0063] FIG. 3a shows the first direction X by means of an arrow. In this context, the term unloaded state can be used to describe a position in which no significant supporting force acts vertically on the wheel 90. For example, this position is assumed when the support roller 30 no longer makes contact with the underlying surface due to an inclination of the industrial truck.

[0064] FIG. 3a also schematically shows a sensing device 190, which, for example, can detect the position of the steering fork 70 along the first direction X relative to the rotary bearing 110 as a limit switch. In other embodiments not shown, however, the act of recognizing can be carried out alternatively or in addition to the embodiment shown contactless by means of a Hall sensor and/or a radar sensor.

[0065] FIG. 3b shows a schematic cross-sectional view of the support roller 30 shown in FIG. 3a in a loaded state. This loaded state can for example be assumed if the support roller 30 has contact with the underlying surface. For example, when the weight of the industrial truck (not shown) exerts an axial force on the support roller 30 and the support roller 30 rests on the underlying surface with a supporting force above the second threshold. Between the two positions shown in FIGS. 3a and 3b there is a distance of approx. 3 mm of the steering fork 70 relative to the rotary bearing 110. However, the person skilled in the art knows that shorter or longer distances can also be covered. The changed position can then be detected via the sensing device 190. It is important to note here that the movement in the X direction takes place against the force generated by the elastic means 170, i.e. the second return device, so that the supporting force acting on the support roller 30 can be inferred from the position. When the supporting force is removed again, the support roller 30 can return to the unloaded state shown in FIG. 1.

[0066] FIG. 4 shows a schematic view of a coupling rocker 210 with a first and second support roller 30, 30. The coupling rocker 210 is mechanically arranged between the support rollers 30, 30 and a bearing 212 of the vehicle's supporting structure. The coupling rocker 210 comprises a 214 rocker on which levers 216, 216 are mounted. Bearings 212 are supported by levers 216, 216. The rocker 214 is mounted in bearing 212 so that it can rotate together with the levers 216, 216 around a rotary axis D. This rotation is carried out against the force of a third return device 218 in the form of a rubber-elastic compression spring.

[0067] The coupling rocker 210 further comprises a shock absorbing device in the form of a 250 hydraulic cylinder. A piston 252 of the hydraulic cylinder 250 is supported by means of a connecting element 230 on the rocker 214. The housing of the hydraulic cylinder 250 is supported by the supporting structure of the vehicle.

[0068] In accordance with the invention, i.e. by means of the third return device, the coupling rocker 210 is arranged in a spring-loaded way on the supporting structure of the vehicle. In the embodiment shown, a first and a second support roller 30, 30 are arranged at opposite end areas of the coupling rocker 210. In the embodiment shown, the support rollers with sensing device shown in FIGS. 3a and 3b can be used. However, the person skilled in the art knows that other embodiments may also be used, such as support rollers with pressure sensors in the wheels, and/or support rollers comprising Hall sensors, and/or radar sensors for sensing the supporting force, at least indirectly by measuring a movement along the first direction.

[0069] The hydraulic cylinder 250 fulfils both the function of the shock absorbing device and the function of the control member. For this purpose, a throttle in the form of a control-less hydraulic valve is arranged in the hydraulic cylinder. The movement of the fluid within the hydraulic cylinder 250 from a cylinder chamber above the piston to the cylinder chamber below the piston can be controlled via the hydraulic valve so that in a closed state of the hydraulic valve the movement of the hydraulic cylinder 250 is blocked in order to block a vertical movement, in particular a suspension, of the coupling rocker 210 and the first and second support rollers 30, 30 arranged thereon, and in an open position to release the movement of the hydraulic cylinder 250 in order to enable the vertical movement, in particular suspension, of the coupling rocker 210 and the first and second support rollers 30, 30 arranged thereon. The opening of the valve remains so that the throttling function is maintained, and cushioning is thus ensured.

[0070] FIGS. 5a, 5b show hydraulic circuit diagrams for controlling the hydraulic cylinders 250, 250 according to the embodiments of the invention.

[0071] In the hydraulic circuit diagram shown in FIG. 5a, the hydraulic cylinder 250, shown as a single-acting hydraulic cylinder, is controlled by means of the hydraulic valve Y1. In the embodiment shown there is no connection between the cylinder chambers 254 and 256. In the closed position the hydraulic valve Y1 blocks the movement of the piston 250. However, if hydraulic valve Y1 is in an open position, the movement of piston 252 is released. As shown in FIG. 7, hydraulic valve Y1 can be electrically operated, i.e. electrically closed or opened, by means of a control device 260.

[0072] In an embodiment not shown, there may be a connection between the cylinder chambers so that the movement or resilience of the coupling rocker in the open position can be enabled so that the hydraulic cylinder can perform the functions of the control member. By installing a throttle in the connection between the cylinder chambers, the function of the shock absorbing device can also be realized.

[0073] The embodiment shown in FIG. 5b can essentially have the structure of the embodiment shown in FIG. 5a. In the embodiment shown, the hydraulic cylinder 250, which is shown as a single-acting hydraulic cylinder, is controlled via a throttle element 258 by means of the hydraulic valve Y1. The throttle element 258 enables the flow rate of the fluid to be controlled, thus enabling a particularly cushioned movement when the hydraulic valve Y1 is open. In the embodiment shown in FIG. 5b, an inclination can be actively counteracted by increasing or decreasing the fluid pressure in the hydraulic cylinder 250. This can be supported by a pump medium. FIG. 5b also shows a non-return valve 259 parallel to the throttle element 258. This non-return valve 259 can be used to cushion a retracting movement of the cylinder without cushioning an extension movement in the opposite direction. This allows the extension movement to take place more quickly.

[0074] In the embodiment shown, the cylinders can be extended by increasing the fluid pressure and retracted when the pressure is reduced, in order to additionally counteract a tipping over. By increasing the pressure, it is possible to counteract a movement ofthe coupling rocker with a higher counterforce.

[0075] FIG. 6 is a schematic view of a coupling rocker 210 with a first and a second support roller 30, 30 and a braking means 262 according to an embodiment of the invention.

[0076] The support rollers 30, 30 and the fastening of the support rollers 30, 30 of the embodiment of the coupling rocker 210 shown in FIG. 6 can essentially correspond to the embodiment shown in FIG. 4. However, the 210 coupling rocker shown in FIG. 6 comprises a braking means 262 realized as an electromagnetic brake acting as a control member and/or shock absorbing device. In the embodiment shown, the braking means 262 can be arranged around the rotary axis D and can also be fixed to the supporting structure of the vehicle by means of a holding device (not shown).

[0077] In particular, in addition to the function of the shock absorbing device, the braking means 262 also fulfils the function of the control member. In the realization shown as an electromagnetic brake, the brake blocks a vertical movement, in particular a suspension, of the coupling rocker 210 and of the first and second support rollers 30, 30 arranged thereon, when the electromagnetic brake is switched on and/or a current flows through the coil of the brake. If no current flows through the coil, the vertical movement, in particular the suspension, of the coupling rocker 210 and the first and second support rollers 30, 30 arranged on it is released. In the embodiment shown, two brake means 262, 262 are arranged on the rotary axis D of the coupling rocker 210 at opposite ends. Both braking means 262, 262 can be connected in the same way in order to enable and inhibit the movement of the coupling rocker 210 at the same time. The person skilled in the art knows, however, that even a single 262 brake is sufficient to lock the 210 coupling rocker.

[0078] FIG. 7 shows that the switching contacts S1, S2 are connected in series with the sensing devices of the support rollers and connect the coil of the hydraulic valve Y1 to a voltage source 270. Thus, when both switching contacts S1, S2 are closed, i.e. the two support rollers are in a first position where they are in contact with the underlying surface, the hydraulic valve Y1 is controlled so that it is opened in a first mode and remains open to allow and cushion a movement or springs of the coupling rocker. For example, the inventive control device could be structured in this way. The person skilled in the art knows, however, that a programmable logic controller could also be used as a control device.

[0079] If the industrial truck is tilted and one of the two support rollers on the coupling rocker is relieved, the signal is interrupted, and the hydraulic cylinder blocks the coupling rocker. Thus, the further deflection of the loaded support roller can be prevented. If both support rollers come into contact with the underlying surface again, the hydraulic valve Y1 is opened again due to the detected increased supporting force, so that the drive wheel has sufficient load again, which is required to ensure sufficient traction during starting, steering and braking.

[0080] In embodiments not shown, a fluid pressure within the hydraulic cylinder can also be changed by means of the control device or other control means can be used, such as an alignment of a support roller around the pivot axis detected by a positioning means.

[0081] The circuit shown in FIG. 7 can for example be used to control the hydraulic cylinders shown in FIGS. 5a and 5b. However, the brake fluid shown in FIG. 6 and described above can also be controlled by means of such a circuit if instead of the hydraulic valve coil, the brake fluid coil is connected in the circuit.

[0082] FIG. 8 shows a method 1000 for stabilizing an industrial truck according to an embodiment of the invention. The method comprises the following steps:

detecting 1010 a supporting force with which the support roller is supported on an underlying surface, wherein in the case of at least one first supporting force the support roller is in contact with the underlying surface, and in the case of at least one second supporting force the support roller is not in contact with the underlying surface; and
controlling 1020 of a control member as a function of the detected supporting force, wherein a rotation of the coupling rocker 210 and/or the support roller about a rotary axis is at least partially prevented by means of the control member upon detecting the second supporting force.

[0083] The features depicted in the above description, claims and figures may be essential to the invention in its various embodiments, either individually or in any combination.

LIST OF REFERENCE NUMERALS

[0084] 1 industrial truck [0085] 3, 3, 30, 30 support roller [0086] 4 supporting structure [0087] 5 drive wheel [0088] 6 underlying surface [0089] 7, 70, 70 steering fork [0090] 9, 90, 90 wheel [0091] 11, 110, 110 rotary bearing [0092] 13a, 13b, 130a, 130b ball bearing [0093] 14, 114 pin [0094] 150a, 150b plain bearing [0095] 170 elastic means [0096] 190 sensing device [0097] 210 coupling rocker [0098] 212 bearing [0099] 214 rocker [0100] 216, 216 lever [0101] 218 return device [0102] 230 connecting means [0103] 250, 250 hydraulic cylinder [0104] 252, 252 piston [0105] 254, 256, 254, 256 cylinder chamber [0106] 258 throttle element [0107] 259 non-return valve [0108] 260 control device [0109] 262 braking means [0110] 270 voltage source [0111] 1000 method for stabilizing an industrial truck [0112] 1010 detecting a position [0113] 1020 controlling a positioning cylinder [0114] S1, S2 switching contact [0115] Y1 hydraulic valve [0116] S pivot axis [0117] R rolling axis [0118] X direction [0119] N normal direction [0120] D rotary axis