WO2005108147A1 - Device and method for rectifying traction problems of multiaxle vehicles - Google Patents

Abstract

The invention relates to a device and a method for preventing or rectifying traction problems of multiaxle vehicles, whereby a central control unit (4) is connected to a traction control device (6) for monitoring the traction of the wheels associated with a driving axle. Said central control unit (4) evaluates the acquired data and, if a traction problem is detected, automatically activates an anti-slip regulation system (1) for regulating and/or controlling the slip of the wheels associated with the driving axle and at least one differential lock (3) for distributing the forces and/or torques acting upon the wheels that are associated with the driving axle.

Description

 Device and method for solving traction problems in multi-axle vehicles

The present invention relates to a device and a method for preventing or eliminating traction problems in multi-axle vehicles, in particular in buses, vans, trucks, or the like. The prevention or correction of traction problems should be automatic or driver-independent, i.e. done without driver intervention.

When multi-axle vehicles are used, this often results in driving conditions in which the vehicles have difficulties starting off, in particular on roads covered with snow or ice.

Although applicable to any vehicle, the present invention and the underlying problem with respect to multi-axle commercial vehicles with three or more axles are explained in more detail.

There are generally systems for traction control (ASR), various differential locking devices and systems for regulating air suspension in today's commercial vehicles. These systems each serve to remedy traction problems of the wheels assigned to the drive axle, these systems being predominantly controlled manually.

In vehicles, especially commercial vehicles, the front of the two rear axles is driven in most cases, while the rear axle as a pure trailing axle has no drive function. When starting such a vehicle, the drive wheels may spin due to a lack of static friction, since during the start, the movement of the vehicle body inevitably results in an additional load on the trailing axle and a relief in the drive axle. If this relief of the drive axle exceeds a certain threshold value, this leads to the drive wheels spinning, particularly on wet, snow-covered or ice-covered roads.

Devices are already known in which, for starting, the pressure in the bellows is reduced by spring devices of the trailing axle in order to increase the pressure in the bellows of the drive axle and thus the static friction force of the drive wheels. The pressure in the bellows of the trailing axle is reduced to a minimum value specified by law. A relay control ensures that the high pressure that inevitably occurs in the bellows of the drive axle only occurs over a limited period of time. After this time threshold has been reached, a controller switches the bellows of the trailing axle back to normal working pressure. This avoids overloading the bellows of the drive axle - especially when the multi-axle vehicle is fully loaded.

While traction control is generally activated automatically when a traction problem is detected, the vehicle user must manually actuate any differential locking devices or an axle load shifting device. This is uncomfortable and can lead to considerable driving uncertainties, for example, when driving uphill and the tires suddenly spin when not activated immediately.

The present invention is therefore based on the object of creating an apparatus and a method which are based on simple and inexpensive way increases driving comfort and driving safety in multi-axle vehicles in the event of traction problems.

This object is achieved according to the invention by a device with the features of patent claim 1 and by a method with the features of patent claim 10.

The idea underlying the present invention is that the traction control device present in the vehicle for regulating and / or controlling traction slip of the wheels assigned to the drive axle and at least one differential locking device for distributing the forces and acting on the wheels assigned to the drive axle / or moments are appropriately controlled and automatically activated by a common central control unit if a traction problem is detected.

Thus, the present invention has the advantage over the prior art that in the case of traction problems, the central control unit automatically activates the existing traction control device and the at least one differential lock device, so that the vehicle user does not have to carry out manual activation in the event of a traction problem. This increases both driving comfort and driving safety. The at least one differential lock device is designed, for example, as a longitudinal lock, cross lock, or the like.

Advantageous refinements and improvements of the device specified in claim 1 and the method specified in claim 10 can be found in the subclaims.

According to an advantageous embodiment, the central control unit is additionally provided with an automatic axle load shifting device provided in the vehicle for shifting a load between a non-driven axle and the drive axle for increasing the static friction force of the wheels assigned to the drive axle for a suitable automatic control of the same in the event of a detected traction problem. This increases driving safety through this further measure to eliminate a traction problem. Furthermore, the axle load shifting device does not have to be manually activated by the vehicle user, but is automatically activated by the central control unit when a traction problem is detected. This also significantly increases driving comfort and driving safety.

With the aid of the axle load shifting device, the axle load is primarily shifted from the non-driven to the drive axle, and thus the wheel load on the drive axle is increased, which leads to an increase in the static friction force.

According to a preferred development, the automatic axle load shifting device is designed as a starting aid based on air suspension, with the pressure in the spring bellows of the spring devices of the trailing axle being reduced in order to increase the pressure in the spring bellows of the drive axle and thus the static friction force of the drive wheels. The trailing axis, i.e. the non-driven rear axle is designed, for example, as a liftable trailing axle. However, other configurations, such as a leading axis, a trailing axis, or the like, can also be used.

The central control unit is preferably additionally connected to the shock absorber control or the roll control for a suitable automatic control thereof in the event of a detected traction problem. This increases driving safety even further, since another system that restores traction can be activated automatically by the central control unit in the event of a traction problem. The traction control device for checking the traction of the wheels assigned to the drive axle has at least one sensor device for comparing the wheel speeds of the wheels and / or at least one sensor device for detecting the slip of the wheels assigned to the drive axle.

The rear axle of the multi-axle vehicle is preferably designed as a drive axle. However, the device and the method according to the invention can be used on all drivable axes.

Preferred exemplary embodiments of the present invention are explained in more detail below with reference to the accompanying figure.

As can be seen in the figure, the device according to the present exemplary embodiment has a central control unit 4, which is signal-connected to a traction control device 6. The traction control device 6 has, for example, a sensor device 7 for comparing the wheel speeds of the wheels of the multi-axle vehicle. By comparing the wheel speeds, a slip or a spin and thus a traction problem of a wheel of the drive axle can be detected in a simple manner. The traction control device 6 can for example additionally or alternatively have a sensor device 8 for directly detecting the slip of the wheels assigned to the drive axle. It is obvious to a person skilled in the art that other well-known devices for measuring a traction problem can be integrated in the traction control device or connected to it.

The central control unit 4 also has, for example, a memory device 5 in which predetermined reference values are stored in advance, for example to determine the extent to which the start or end of a tract problems, the extent to which legally permitted limit values have been reached, or the like.

The central control unit 4, as further shown in the figure, is additionally connected to various systems for automatic activation of the same to remedy a detected traction problem. Examples of such traction elimination systems connected to the central control unit 4 and thus combined with one another are explained in more detail below.

An example of such a system for eliminating a traction problem is a traction control device 1. As is generally known, a drive wheel of the multi-axle vehicle is subject to slippage when the vehicle starts to drive or when it is accelerated, i.e. when the driving force of the driving wheel exceeds a frictional force developed between the tire of the driving wheel and the road surface [= the coefficient of friction between the tire and the road surface x the load of the vehicle weight on the driving wheel (wheel load)]. The frictional force acts in the driving or longitudinal direction of the vehicle. The amount of slip can be represented by an amount of slip that depends on the peripheral speed of the drive wheel and the speed of the vehicle. The frictional force between the drive wheel tire and the road surface, which sets the upper limit of the effective drive force of the drive wheel, changes with the amount of slip.

For example, the amount of slip can be controlled by a corresponding traction control device in such a way that the longitudinal frictional force becomes maximum in order to maintain the maximum drive efficiency of the vehicle, while the lateral frictional force exhibits the smallest possible drop in order to prevent the vehicle from sliding off or sliding sideways. This is done, for example, via an engine intervention Torque of the engine is controlled by switching an ignition device of the vehicle engine on and off or by allowing or stopping (throttling) the fuel supply from a fuel supply device for the engine in such a way that excessive slipping or spinning of the drive wheels is prevented.

Furthermore, traction control devices for wheels of a driven rear axle are known, a braking force regulator being positioned between the rear wheel brake cylinders and the inlet valve in order to keep the braking pressure of the rear wheels lower than that of the front wheels, thereby stabilizing the vehicle and preventing overbraking of the rear wheels.

Alternatively, to avoid locking of wheels when braking, the brake fluid pressure in a wheel cylinder can be reduced by a modulator while performing traction control, which under certain conditions is increased again, so that the braking torque (total braking torque including braking system torque) with respect to time is increased linearly.

Furthermore, the central control unit 4 is preferably additionally connected to at least one, preferably a plurality of differential locking devices 3.

Differential locks assigned to a differential gear are generally known in order to lock the driven wheels of the vehicle together and thereby to be able to deactivate the differential gear. For example, a lock includes a hydraulic mechanism with a source that supplies pressurized fluid that actuates a clutch with a pack of coated disks. The hydraulic mechanism preferably has a rotating cylinder and a piston therein, the pressurized fluid from a stationary inlet ring into a bore rotating disk is introduced, which is in communication with the pressure chamber of the cylinder. The clutch is located outside of the ring gear bearing base, thereby avoiding the load bearing capacity of the ring gear bearing of the differential gear. For example, the differential lock can also comprise two clutch halves, with which a form-fitting connection between a wheel drive shaft and a differential housing can be established in the usual way. The differential lock includes, for example, a piston which is directly displaceable longitudinally in a housing bore of the rear axle gear housing made of metal and which can be engaged when compressed air is applied and released when compressed air is released as a result of a spring force. For this purpose, the piston is sealed with an O-ring on the circumference of the housing bore, this housing bore must have a very high surface quality in order to achieve a corresponding sealing effect on the one hand and to protect the O-ring on the other hand.

Of course, other versions of differential locks are possible. The differential lock device can be designed, for example, as a longitudinal lock, cross lock, or the like.

If, for example, the associated wheels are spinning by the traction control device 6 or by the sensor devices 7 and 8 assigned to them on a sensed drive axle, the necessary differential locks are automatically inserted, for example, depending on the speed and speed of the engine and / or the wheels. The locks can be activated automatically either individually or as a whole by the central control unit 4. After automatic recognition of the end of the situation or the elimination of the traction problem, ie the traction is restored by the measures taken, the differential locks are automatically deactivated again by the central control unit 4. There- in the case of a predetermined waiting time can also be taken into account by the central control unit, in which the locks remain in the activated state after the removal of the traction problem has been identified. Such predetermined waiting times can, for example, also be stored in the memory device 5 of the central control unit 4 and can also be applied analogously to other traction elimination systems.

When a traction problem is detected, the central control unit 4 automatically activates the arranged or the arranged differential locks 3 in a suitable manner in order to remedy the traction problem automatically without manual intervention by the vehicle user.

As can also be seen in the figure, the central control unit 4 is advantageously additionally connected to an automatic axle load shifting device 2. In this case, the multi-axle vehicle preferably has an additional axle assigned to the drive axle, which is partially relieved during a starting process or in the event of a traction problem, for example by reducing the operating pressure of the air suspension bellows of the additional axle to a residual pressure. The axle load released in the process is thus also transferred to the drive axle, i.e. this increases the axle load of the drive axle. The additional axle can be designed, for example, as a liftable trailing axle, leading axle, trailing axle, or the like.

When a traction problem is detected on the drive axle, the load transfer is automatically initiated by the central control unit. The legally permitted limit values are preferably taken into account, which are stored in advance, for example, in the storage device 5 of the central control unit 4, as previously explained. When a traction problem is detected, the central control unit 4 preferably controls the axle load shifting device 2 in stages in such a way that discrete axle load shifts are carried out or activated gradually until the traction problem is eliminated. For example, in a first stage, an axle load shift can only take place up to a load, and then, upon detection of a traction problem that has not yet been remedied, a further axle load shift can take place up to the legally permitted maximum load limit. After certain discrete load increases, test loops are run through, from which the central control unit 4 can analyze to what extent the traction problem has been remedied or a further axle load shift is necessary. Alternatively, the axle load can be shifted immediately up to the maximum legally permitted limit.

The central control unit 4 is preferably also connected to the shock absorber control or roll control 9 of the multi-axle vehicle, the shock absorber hardness also being changed in a suitable manner when a traction problem is detected.

The present invention thus provides a device and a method for automatically preventing or correcting traction problems, wherein various traction correction systems present in the multi-axle vehicle can be automatically activated in a suitable manner at the same time when a traction problem is detected by a central control unit. The individual systems can be combined with one another in a favorable manner, controlled individually, or certain systems can be switched on in succession in accordance with a previously stored priority list. Furthermore, various sequence programs of the individual systems can be stored in the central control unit 4 or in the storage device 5. Thus, the present invention provides an inexpensive traction elimination system because the existing components are generally already present in multi-axle vehicles. The traction elimination systems must be connected to one another in a suitable manner with a common central control unit in such a way that suitable control is ensured when a traction problem is identified.

Although the present invention has been described above on the basis of preferred exemplary embodiments, it is not restricted thereto, but rather can be modified in many ways.

In addition to the above, the following modification of the object shown in the figure is to be pointed out: It is also conceivable for such an implementation in which both the central control unit 4 and the traction control device 6 are dispensed with. That The detection of a driving state in which there are traction problems or in which there are traction problems is carried out using the traction control device 1, which then also controls or selects the additional systems or devices which are to be activated in addition to the traction control device 1 these are components 3 and possibly 2 and / or 9.

Furthermore, such an implementation is also conceivable, in which the central control unit 4 is present, but the traction control device 6 is dispensed with. In this case too, a driving state in which traction problems occur or in which there are traction problems is identified using the traction control device 1. The control or selection of the additional systems or devices to be activated in addition to the traction control device 1, in which components 3 and possibly 2 and / or 9 are then carried out by the central control unit 4. rale control unit 4 then has the function of a higher-level controller or coordinator.

In addition or as an alternative to the first embodiment of the device or method according to the invention described above, in which the focus is on a combination of a traction control device with at least one differential lock and an axle load shifting device, a further second embodiment will be described below in which a combination of a traction control device with at least one lock contained in the vehicle, in particular a differential lock. That It is primarily a combination of the automatic activation of locks with a traction help management or the integration of the locks contained in the vehicle as part of a traction aid or traction help. Automated activation of locks and traction help should be possible in the event of traction problems.

As a background to this embodiment, the following should be stated: In today's commercial vehicles, there are mostly systems for regulating the traction slip, these systems are referred to as traction control systems (ASR), systems for operating various locks arranged in the vehicle, the locks being predominantly electronically controlled and there being the locks can be longitudinal locks or cross locks, as well as systems for regulating the air suspension, which are used, for example, as part of a level control.

With the aid of the device or the method according to this further embodiment, an intelligent interconnection of the systems listed above is to be achieved in order to give or guarantee the driver maximum comfort and driving safety. The following procedure is proposed for this: If the wheels or at least one wheel is detected on a sensed axle, in particular on a drive axle, the necessary locks are automatically inserted. This can take place, for example, as a function of the speed, in particular the vehicle speed and / or the speed of the engine and / or the wheels. For vehicles that are equipped with multiple locks, these are so-called four-wheel drive vehicles, for example a 6x6 vehicle (vehicle with three axles with two wheels each, all three axles being driven), the locks can be inserted individually or as a whole , The necessary locks are those locks with which it is possible to reduce the torque acting on the spinning wheel.

The spinning of the wheels or the at least one wheel is preferably detected with the aid of the traction control device. However, it is also conceivable that this can be done with the help of a higher-level system or controller. Depending on the implementation, the locks can be activated directly from the traction control device or from a higher-level system or higher-level controller, in particular a central control unit.

Is the end of the driving state in which the traction problem arose before initiation or implementation of the stabilizing interventions or in which the traction problem existed, or is it recognized, or is it simply recognized that the traction is restored, ie the traction problem is eliminated , the locks are automatically deactivated. The locks can be deactivated either immediately after the point in time when it is recognized that traction has been restored, or else taking into account a waiting time. In this case, the locks remain a pre-determined after the point in time when it was recognized that the traction was restored. certain period of time active before they are then deactivated. This means that the locks are still active for a predetermined period of time despite the traction being restored.

So far, the combination of a traction control device with locks has been dealt with in connection with this second embodiment. Of course, in addition to these two components, other components that have an influence on the traction of the vehicle can be activated in driving conditions in which there is insufficient traction or in which traction problems arise.

In particular in the case of vehicles which are equipped with an axle load shifting device, a 6x2 vehicle may be mentioned as an example, i.e. A vehicle with three axles, of which one axle is designed as a steerable axle, another axle as a drive axle and another axle as a liftable trailing axle, can automatically initiate the load shift upon detection of a traction problem on the drive axle. In such a case, in addition to the traction control device and the locks, the axle load shifting device can also be used to remedy the traction problem or to restore traction or as a starting aid.

In addition to the traction control device and the locks, if the vehicle is equipped accordingly, a shock absorber control or roll control can also be used to remedy the traction problem or to restore traction or as a starting aid. For this purpose, the shock absorbers are adjusted to a "harder" and thus safer level.

The traction help is ended using the standard traction help function. In summary, it can be stated: It is a device for influencing the traction behavior of drive wheels of a vehicle, the vehicle having a plurality of axles with respectively assigned wheels, the axles being at least one steerable steering axle and one with drive means arranged in the vehicle operatively connected drive axle. A differential lock should be assigned to this drive axle from an operational point of view. In addition, the vehicle has traction slip influencing means, in particular a traction control system, with which, when a condition specified for the traction slip present on the wheels of the drive axle is met, the traction slip is associated with braking means associated with the driver of the wheels of the drive axle and / or in the drive means is reduced, the differential lock assigned to the drive axle being actuated independently of the driver to influence the traction present on the drive axle and / or on the driven wheels when a defined state of the drive slip influencing means is present.

Depending on the level of equipment, the vehicle has a further third axis which is spatially assigned to the drive axle, in which case axle load influencing means are provided with which the axle load acting on the third axle can be influenced. In the event that the vehicle has several drive axles, the vehicle has further differential locks, in particular one differential lock for each drive axle and possibly further differential locks inserted between the drive axles.

A third embodiment of the device according to the invention or of the method according to the invention can be the following: To eliminate traction problems or to restore traction, the traction control device that is present in the vehicle anyway is used first, in any case. In addition to the traction control system at least one further component is used, ie activated, this further component being selected from various components with which the traction of the vehicle can be influenced. These components, from which at least one more is selected, ie at least one of which is activated, are locks arranged in the vehicle and an axle load shifting device and / or a shock absorber control and / or a roll control and / or an air suspension.

In this embodiment, a higher-level controller or a higher-level system is advantageously present, which carries out the coordination or selection of the systems or components to be activated, so that in addition to the traction control system, the system which is optimal for improving the traction is used.

In summary, it can be stated: It is a device for influencing the traction behavior of drive wheels of a vehicle, the vehicle having a plurality of axles with respectively assigned wheels, the axles being at least one steerable steering axle and one with drive means arranged in the vehicle operatively connected drive axle. The vehicle has traction slip influencing means, in particular a traction control system, with which, when a condition specified for the traction slip present on the wheels of the drive axle is met, the traction slip associated with driver-independent interventions in the wheels of the drive axle and / or in the drive means is reduced. In addition, the vehicle has further components or systems with which the traction on the drive axle or the traction of the driven wheels can be influenced. These further components or systems should be the following: A differential lock operatively assigned to the drive axle and axle load influencing means with which the on a Axle load acting on the third axis can be influenced, this third axis being spatially assigned to the drive axis and / or an air suspension and / or a shock absorber adjustment and / or a roll control. If there is a defined state of the traction slip influencing means, at least one further of these components is activated or selected for additionally influencing the traction present on the drive axle or on the driven wheels.

In the event that the vehicle has multiple drive axles, the vehicle has further differential locks. In particular, a differential lock for each drive axle and possibly other differential locks inserted between the drive axles.

At this point, the design of the vehicles will be discussed. The first embodiment is based on a vehicle which has a plurality of axles, each with associated wheels, the axles being at least one steerable steering axle, a drive axle operatively connected to drive means arranged in the vehicle, and a third axle spatially assigned to the drive axle , Axle load influencing means or an axle load shifting device are provided with which the axle load acting on the third axle can be influenced. Such a vehicle usually has at least three axles.

The second and third embodiment is based on a vehicle which has at least two axles. So that an axle load shifting device can also be used, this vehicle should also have at least three axles.

The traction control device is traction slip influencing means, with which, when one is met, one for the wheels of the drive axle, ie the Drive wheels of the vehicle present drive slip predetermined condition of the drive slip is reduced by driver-independent interventions in the wheels of the drive axle associated brake means and / or in the drive means.

If there is a defined state of the traction control device or of the traction control means, another component present in the vehicle, with which the traction can be influenced, is activated independently of the driver to remedy the traction problem. The defined state of the traction slip influencing means is advantageously present when the condition specified for the traction slip is fulfilled and / or when the traction slip influencing means emits a warning signal that the driver-independent interventions in the braking means and / or in the driving means of the vehicle are carried out Indicates the vehicle, and / or if the drive slip influencing means emits control signals which are provided for carrying out the driver-independent interventions in the brake means and / or in the drive means.

The condition stipulated for the drive slip is simply fulfilled when the drive slip occurring at the wheels of the drive axle exceeds a predetermined drive slip threshold value, the drive slip resulting as a function of the difference between the driving speed of the vehicle and the peripheral speed of the wheels of the drive axle.

The device according to the invention or the method according to the invention is generally formulated as a device or a method for influencing the traction behavior of drive wheels of a vehicle.

Finally, it should also be pointed out that advantageous combinations of the individual configurations or implementations described above are conceivable. Ie individual Features or aspects that are described in connection with one configuration or implementation can certainly be used in another implementation or configuration.

Claims

DaimlerChrysler AG patent claims 1. Device for eliminating traction problems in multi-axle vehicles; with at least one drive axle; with a traction control device (1) for regulating and / or controlling a traction of the wheels assigned to the drive axle; a traction control device (6) for checking the traction of the wheels assigned to the drive axle; and at least one differential locking device (3) for distributing the forces and / or moments acting on the wheels assigned to the drive axle, characterized in that there is a central control unit (4) which is used to receive traction data and to detect a traction problem with the Traction control device (6) and for suitable automatic control of the traction control device (1) and the at least one differential locking device (3) in the event of a detected traction problem. 2. Device according to claim 1, characterized in that the at least one differential locking device (3) is designed as a longitudinal lock, cross lock, or the like. 3. Device according to claim 1, characterized in that a non-driven axis is present, wherein the central control unit (4) is additionally connected to an axle load shifting device (2) for shifting a load between the non-driven axle and the drive axle in order to increase the static friction force of the wheels assigned to the drive axle for a suitable automatic control thereof in the event of a detected traction problem is. 4. The device according to claim 3, characterized in that the automatic axle load displacement device (2) is designed as a starting aid based on an air suspension. 5. The device according to claim 3, characterized in that the non-driven axle is designed as a liftable trailing axle, leading axle, trailing axle, or the like. 6. The device according to claim 1, characterized in that the central control unit (4) is additionally connected to the shock absorber control for a suitable automatic control thereof in the event of a detected traction problem. 7. The device according to claim 1, characterized in that the traction control device (6) has at least one sensor device (7) for comparing the wheel speeds of the wheels of the multi-axle vehicle. 8. The device according to claim 1, characterized in that the traction control device (6) at least one Sensor device (8) for detecting the slip of the wheels assigned to the drive axle. 9. The device according to claim 1, characterized in that the rear axle of the multi-axle vehicle is designed as a drive axle. 10. Method for automatically correcting traction problems in multi-axle vehicles; in which a traction slip of the wheels assigned to a drive axle is regulated and / or controlled by means of a traction control system (1); in which the traction of the wheels assigned to the drive axle is checked by means of a traction control device (6); and in which, by means of a differential locking device (3), the forces and / or moments acting on the wheels assigned to the drive axle are distributed, characterized in that by means of a central control unit (4) the traction control device (6) receives traction data and traction problems are recorded and the Traction control device (1) and the at least one differential locking device (3) are automatically controlled in a suitable manner in the event of a detected traction problem. 11. The method according to claim 10, characterized in that the at least one differential locking device (3) is designed as a longitudinal lock, cross lock, or the like. 12. The method according to claim 10, characterized in that by means of the central control unit (4) additionally an axle load shifting device (2) for moving a load between a non-driven axle and the drive axle for an increase in the static friction force of the wheels assigned to the drive axle is automatically controlled in a suitable manner in the event of a detected traction problem. 13. The method according to claim 12, characterized in that the automatic axle load shifting device (2) is designed as a starting aid based on an air suspension. 14. The method according to claim 12, characterized in that the non-driven axle is designed as a liftable trailing axle, leading axle, trailing axle, or the like. 15. The method according to claim 10, characterized in that the central control unit (4) additionally controls the shock absorber control in a suitable manner in the event of a detected traction problem. 16. The method according to claim 10, characterized in that the traction control device (6) is designed with at least one sensor device (7) for comparing the wheel speeds of the wheels of the multi-axle vehicle. 17. The method according to claim 10, characterized in that the traction control device (6) is formed with at least one sensor device (8) for detecting the slip of the wheels assigned to the drive axle. 18. The method according to claim 10, characterized in that the at least one differential locking device (3) depending on the speed and / or speed of the engine and / or the wheels by the central control unit (4) is automatically activated in the event of a detected traction problem. 19. The method according to claim 10, characterized in that a plurality of differential locking devices (3) individually or collectively by the central control unit (4) are automatically activated in the event of a detected traction problem. 20. The method according to claim 12, characterized in that the central control unit (4) controls the automatic axle load shifting device (2) in accordance with the legally permitted limit values. 21. The method according to claim 12, characterized in that a gradual increase in the axle load distributed by the axle load shifting device (2) as a function of the traction data resulting therefrom is carried out by the central control unit (4). 22. The method according to claim 12, characterized in that the central control unit (4) first performs a load and then, depending on the traction data acquired, an overload of the axle load distributed by the axle load shifting device (2). 23. The method according to claim 10 and 12, characterized in that after detecting an end of the traction problem, the traction control device (1), the at least one differential locking device (3) and the axle load shifting device (2) are automatically deactivated by the central control unit (4). 24. The method according to claim 23, characterized in that upon detection of an end of the traction problem, a predetermined waiting time is waited by the central control unit (4) before the traction control device (1), the at least one differential locking device (3) and the axle load shifting device (2 ) can be deactivated by the central control unit (4).