AT524936A4 - Platform for at least four-wheel motor vehicles with electric drive - Google Patents

Abstract

A platform for at least four-wheel motor vehicles with an electric drive comprises at least one front and at least one rear axle group, which are spaced apart from one another in a longitudinal direction of the platform and of which at least the front axle group has wheels (11) which can be steered about a respective pivot axis (14) and which are attached to Wheel carriers (12) are rotatably mounted about wheel axles (13) and are driven individually by electric motors, the wheel carriers (12) pivotable about the pivot axes (14) being connected to one another via a connecting rod (31). The wheels (11) are steered only by means of drive and/or braking forces. The platform has a modular structure and has a chassis module (1) and a front axle module (2) forming the front axle group, which can be connected as a whole to the chassis module (1) and can be removed from the chassis module (1).

Description

The invention relates to a platform for at least four-wheel motor vehicles with an electric drive, comprising at least one front and at least one rear axle group which are spaced apart from one another in a longitudinal direction of the platform and of which at least the front axle group has wheels which can be steered about a respective pivot axis and which are attached to Wheel carriers are rotatably mounted about wheel axles and are driven individually by electric motors, the wheel carriers, which can be pivoted about the pivot axes, being connected to one another via a connecting rod and the wheels being steered only by means of drive

and/or braking forces.

platforms for four-wheel motor vehicles with electric drive

are known in different embodiments.

Among other things, with regard to autonomous driving, where there are also areas of application with limited maximum speeds, for example in the range of up to 80 or 90 km/h, there are new requirements and

Possibilities, which also lead to new starting points

have led. So have already been specially designed for such purposes

customized platforms developed in a simple way

can be equipped with different structures,

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to enable different purposes, such as passenger transport or load transport.

Such platforms are also called skateboard platform

designated.

In four-wheel motor vehicles with electric drives, where the two steerable wheels of a front axle group are driven individually by means of wheel hub motors, it is already known to steer the wheels only by means of drive and/or braking forces. This emerges, for example, from DE 10 2019 104 391 A1 or WO 2020/169134 A1. The wheel carriers belonging to an axle, which can be pivoted about pivot axes in order to steer the wheels, are connected by means of a connecting rod. There is neither a part mechanically acting on the connecting rod nor a separate steering actuator for steering the wheels. Rather, the motor vehicle is steered in that the individual wheel drives of the wheels arranged on the steerable axle are used to transmit drive and/or braking torques to these wheels, which steer the wheels in a predetermined direction. Braking torques for steering the wheels can be exerted instead or additionally by means of a mechanical braking device for the respective wheel. In the event that a single-wheel drive fails, there is a holding device which is connected to the connecting rod

cooperates to brake or block them.

A similar device also emerges from US Pat. No. 10,562,400 B2. The holding device, in order to be able to determine each of the steerable wheels in a given angular position, acts here directly with the pivot bearing of the

Wheel carrier together around the pivot axis.

In contrast, in the steering device known from US Pat. No. 9,221,495 B2, the wheels are steered by means of steering actuators, which actively adjust the angular position of a respective wheel carrier about the pivot axis. These steering actuators are available in addition to the electric individual wheel drives. The electric motors are outside of the respective wheel

arranged and connected to this via a drive shaft.

Furthermore, a modular construction of a platform has already become known to the effect that there is a separate wheel module for each of the wheels. In addition to the wheel and its suspension, this includes an electric wheel hub motor for driving, a brake and an electric steering actuator for actively steering the wheel. The wheels are therefore steered by means of separate steering actuators. the

Wheel modules are mounted on a chassis module.

The object of the invention is to provide an advantageous platform of the type mentioned at the outset which, with a simple design, has a high degree of flexibility for adapting to different applications. According to the invention

this is achieved through a platform with the characteristics of the

claim 1.

The platform according to the invention has a modular structure, which includes a chassis module and a front axle module forming the front axle group. This front axle module, which has steerable right and left wheels, the wheels being steered only by means of driving and/or braking forces, is integral with the

Chassis module can be connected and removed from the chassis module.

Because the invention has a front axle module,

preferably also a rear axle module,

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provides, which can be connected as a whole to the chassis module and can be removed from the chassis module, a modular design of a platform is made possible, in which the steerable wheels are steered only by means of drive and/or braking forces, where necessary , the steerable right and left wheels of a respective axle group via a connecting rod

associate.

The front and/or rear axle module is advantageously connected to the chassis module by means of a screw connection, with the front and/or rear axle module advantageously having a rigid base unit via which the connection to the chassis module takes place and on which

the suspension is installed.

If, in the platform according to the invention, the rear axle group is also designed as a modular axle module, which is preferred, the wheels of this rear axle module can be non-steerable or also steerable. If the wheels of the rear axle module can be steered, they are preferably driven individually by means of electric motors and the steering takes place only by means of drive and/or

braking forces.

In an advantageous embodiment of the invention, the wheels of the front axle module and/or rear axle module are suspended via a trailing arm wheel suspension, which has at least one left and at least one right trailing arm, which are each pivotably connected to the base unit about a transverse axis. The pivoting of the trailing arm relative to the base unit is expediently spring-loaded and damped. Through this

Be trained, especially if it's an axis

with wheels driven individually by electric motors and steered only by means of drive and/or braking forces, advantages are achieved in terms of the required installation space. This also advantageously makes it modular

Training of the axle group allows.

Appropriately, it is provided that an upper and a lower trailing arm are provided for both the left wheel and the right wheel, which mount the wheel carrier, which is assigned to the respective wheel, pivotably in the manner of a parallelogram guide. The upper and lower trailing arms on the respective side of the front and/or rear axle module are thus connected at different heights to the wheel carrier, which is assigned to the respective wheel, so that they can pivot about a respective transverse axis and are at different heights on the base unit of the axle module respective transverse axis pivoted. It can be achieved that there is no change in the angular position of the pivot axes of the wheel carriers (ie no change in the caster angle) when the trailing arms are pivoted relative to the base unit about the transverse axes. This leads to significant advantages in the steering of the wheels only by means of drive and / or braking forces when there are different pivot positions of the trailing arm about the respective transverse axis, which

arise when deflecting.

The suspension of the trailing arms is preferably via torsion bar springs. These are expediently arranged coaxially to the respective transverse axis about which the respective trailing arm to which the respective torsion bar spring is connected can be pivoted. In this case, these transverse axes are advantageously related to the longitudinal direction of the platform

and/or offset in height from one another. It

This means that torsion bar springs arranged coaxially to the transverse axes can extend over more than half of the track width. In addition, an advantageous adjustment of the spring force of the torsion bar springs is made possible by this design, in which purely rotational movements of the torsion bar springs occur. For this purpose, in a region spaced apart from the connection of the torsion bar spring with the trailing arm, a holding part is connected to the respective torsion bar spring in a rotationally fixed (= non-rotatable) manner but displaceable in relation to the transverse direction parallel to the transverse axis, with the holding part being mounted on the base unit of the axle module so that it can be adjusted in the transverse direction is. The spring force of the respective torsion bar spring can thus be influenced by the displacement of the holding part relative to the base unit. In this case, an actuator for displacing the holding part in the transverse direction relative to the base unit is preferred

present.

In an advantageous embodiment of the invention, there is a holding device by means of which the current angular position of each of the steerable wheels of the front axle module and/or rear axle module about the respective pivot axis can be determined with a holding force. Such a holding device is advantageous if one of the electric motors of the wheels of a steerable axle fails. A desired angular position of the wheels can then still be set with the remaining electric motor and/or a mechanical braking device for the respective wheel and the wheels can be fixed in the set angular position with the holding device. In one possible embodiment, the holding force with which the determination takes place can only be selected to be large enough that this can be applied by means of the

Driving and / or braking forces can still be overcome. It can

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thus by means of the driving and / or braking forces even with a malfunction of the holding device nor a steering

steerable wheels are carried out.

Further advantages and details of the invention are explained below with reference to the attached drawing. In

this show:

Fig. 1 is an oblique view of an embodiment of a

platform according to the invention;

Figure 2 is a side view; Fig. 3 is a view from below, Fig. 4 is an oblique view analogous to Fig. 1 but with

removed axis modules;

5 shows an exploded view of a front axle module (without the parts arranged on the wheel carrier on the left in relation to the direction of travel);

Fig. 6 is an oblique view (without the on both wheel carriers

arranged parts);

Fig. 7 is a plan view; Fig. 8 is a front view; Fig. 9 is a side view;

Fig. 10 is a section along line A-A of Fig. 8;

11 shows an exploded view of a second exemplary embodiment of a front axle module (without the parts arranged on the left-hand wheel carrier);

12 is an oblique view;

Fig. 13 is a front view;

Fig. 14 is a side view;

Fig. 15 is an exploded view of a front axle module according to a third embodiment of the invention (without the on the left wheel carrier

arranged parts);

partially schematic representations.

A first exemplary embodiment of the invention is explained below with reference to FIGS. 1 to 10. FIG. The modular platform has a chassis module 1, a front axle module 2 and a rear axle module 3. A rigid supporting platform base 1a of the platform is formed from the chassis module 1 . In the figures, the chassis module 1 is only shown schematically as a contoured plate. In practice, the chassis module will have different parts, e.g. Preferably, accumulators for the electric drive are also attached to the platform base la of the chassis module (not

shown in the figures).

The front right and left wheels in relation to the direction of travel can be steered. The motor vehicle therefore has a steered front axle. A front axle group has the front wheels together with their wheel suspension and forms the steered front axle. The front axle group is formed by the front axle module, which is described further below

is described in more detail.

The rear wheels are not steerable in the embodiment. A rear axle group includes the rear wheels together with their wheel suspension and forms the rear axle. In the exemplary embodiment, the rear axle group is formed by the rear axle module 3 . It could also be a rear one

Axle module are used, which also steerable wheels

having. This could be analogous to the front axle module

be trained.

A platform according to the invention could also have more than one

have front and/or more than one rear axle module.

Such a platform can also be used as a skateboard platform

be designated.

The rear axle module 3 is designed with a rigid axle 4 in the exemplary embodiment. This is suspended from a base unit 6 of the rear axle module 3 by means of leaf spring assemblies 5 . The inherently rigid base unit is attached to the chassis module 1 by means of a screw connection. For this purpose, screws 7 that pass through openings in the base unit 6 are screwed into screw threads of the chassis module 1 . The connection between the chassis module 1 and the rear axle module 3 can be rigid or, as indicated, include spring and / or damping elements 9, such as rubber bushings or hydraulic bushings to the transmission of

reduce vibration and/or noise.

The wheels 8 rotatably mounted by the rigid axle 4 can be driven by electric motors, for example by wheel hub motors. An additional mechanical braking device for each wheel, as is known, is

expediently available.

The front axle module 2 has an inherently rigid base unit 10 which carries the wheel suspension. The base unit 10 is used to connect to the chassis module 1. This is preferably designed as a screw connection. Screws 18 pass through openings in the base unit 10 and

are screwed into the screw thread of the chassis module 1. the

Connection can be rigid here or it can, as indicated, suspension and / or damping elements 19 may be interposed, for example in the form of rubber bushings or hydraulic bushings to the transmission of

reduce vibration and/or noise.

The right and left wheels 11 of the front axle module 2 are rotatably mounted on wheel carriers 12 about wheel axles 13 . The wheels 11 are steerable. For this are the right and left

Wheel carrier 13 mounted pivotably about pivot axes 14 .

The wheels 11 of the front axle module 12 are driven individually by electric motors 15 . In the exemplary embodiment shown, the electric motors are designed in the form of wheel hub motors. In principle, it would also be conceivable and possible for there to be electric motors attached to the base unit 10, which are connected to the respective wheel

1l are connected via a respective drive shaft.

A mechanical braking device is provided for each wheel 11 . In this context, a

Brake disc 16 and a brake caliper 17 are shown.

It would also be conceivable and possible for braking alone

done by the electric motors.

The wheels 11 of the front axle module 12 are suspended from the base unit 10 via a trailing arm wheel suspension. There is a lower trailing arm 21 and an upper trailing arm 20 for both the left wheel and the right wheel 11 . The respective lower trailing arm 21 is connected to the base unit 10 such that it can pivot about a respective lower transverse axis 22,

on the other hand, about a respective lower transverse axis 23 with the

respective wheel carrier 12 pivotally connected. The respective upper trailing arm 20 is connected to the base unit 10 such that it can pivot about a respective upper transverse axis 24 and is connected to the respective wheel carrier 12 such that it can pivot about a respective upper transverse axis 25 . The transverse axes 22-25 are perpendicular to the longitudinal direction of the platform. The longitudinal direction of the platform

is parallel to the direction of straight travel.

The upper transverse axes 24 are higher than the lower transverse axes 22 and the upper transverse axes 25 are higher than the lower transverse axes 23. A parallelogram guide for the respective wheel carrier 12 is formed. When the trailing arms 20, 21 are pivoted about the transverse axes 24, 22 relative to the base unit 10, the change

Angular positions of the wheel carrier 12 therefore not.

The connections of the trailing arms 20, 21 with the wheel carriers 12 are in the form of ball joints. The wheel carriers 12 can thus also be pivoted about the respective pivot axis 14 relative to the trailing arms 20, 21 in order to rotate the wheels 11

to steer.

The inclination of the pivot axes 14 upwards backwards or forwards represents the caster angle. As can be seen from FIG. Preferably, a platform according to the invention will have the caster angle equal to 0° or a (slightly) negative caster angle for the steered wheels

trained (less than 5°).

The angle of inclination of a respective pivot axis 14 upwards

inside is called spreading. As from Fig. 7

As can be seen, the respective pivot axis 14 is aligned vertically in the exemplary embodiment when viewed from the front, i.e. the spread is 0°. Preferably, in a platform according to the invention for the steered wheels, the spread is set to a value of 0° or a (slight)

negative value (less than 5°).

The torque differences between the right and left wheels, in order to set the position of the wheels about the pivot axes 14, can be kept small by the formation of the caster angle and the spread mentioned. There may be low required drive or braking torques

Steering the wheels can be achieved.

The pivoting of the trailing arms 21 about the transverse axes 22 is spring-loaded. For this purpose, a respective torsion bar spring 26 is present for the respective lower trailing arm 21 . This respective torsion bar spring 26 extends coaxially to the respective lower transverse axis 22 about which the respective lower trailing arm 21 is pivotable. So that the torsion bar springs 26 can be as long as possible, i.e. can have a length greater than half the track width, the lower transverse axes 22 for the right and left lower trailing arm 21 are offset from one another, in the exemplary embodiment in relation to the longitudinal direction of the platform, i.e. one of the two Transverse axis 22 is further forward and the other of the two transverse axes 22 further back. Correspondingly, the upper transverse axes 24 of the right and left upper trailing arms 20 are based on the

Longitudinally offset from the platform to each other.

The offset of the lower and upper transverse axes 22, 24 could

instead or in addition, also in height.

In the exemplary embodiment, the trailing arms 20, 21 are of different lengths on the right and left sides corresponding to the offset of the transverse axes 22, 24, so that the wheel axles 13 of the right and left wheels 11 coincide. The wheel axles 13 of the right and left wheels 11 could also be related to the longitudinal direction of the platform

be offset to each other.

In a region spaced apart from the connection to the respective trailing arm 21 , the respective torsion bar spring 26 is non-rotatably connected to the base unit 10 . A holding part 21 is used for this purpose, which is in a non-rotatable connection with the respective torsion bar spring 26 . In order to enable the spring force to be adjusted, a respective holding part 27 is connected to the respective torsion bar spring 26 so that it can be displaced in relation to the transverse direction parallel to the transverse axes 22-25 and is mounted on the base unit 10 so that it can be displaced in the transverse direction. An electric actuator 28 is preferably provided in each case for displacing the respective holding part 27 in the transverse direction. It is thus possible by means of an electrical control device (not shown in the figures) to adjust the suspension, even when the vehicle is in operation.

take place.

The respective holding part 27 is non-rotatably connected to the respective torsion bar spring 26 via a respective connecting piece 29. Its rotational position relative to the holding part 29 can be adjusted and fixed, whereby a pretension of the respective torsion bar spring 26 is set

can be.

The pivoting of the respective lower trailing arm 21 is

damped by a respective damper 30. in the

Embodiment are provided as a damper 30 rotary damper, via which the lower trailing arm 21 can be pivoted about the lower transverse axes 22 at a downward

projecting legs 10a of the base unit 10 are mounted.

The right and left wheel carriers 12 which can be pivoted about the pivot axes 14 are connected to one another via a connecting rod 31 which synchronizes the pivoting of the right and left wheel carriers 12 about the pivot axes 14 . The connecting rod 31 has a center piece 31a, which is mounted on the base unit 10 by means of bearing legs 10b of the base unit 10 so that it can be displaced in the transverse direction. A right and a left side piece 31b, 31c are articulated to the center piece 31a, the side pieces 31b, 31c being connected to the wheel carriers

12 are articulated.

A more than three-piece or a two-piece construction of the connecting rod (with the two side pieces 31b, 31c being extended and connected directly to one another) is possible

also conceivable and possible.

The displaceability of the center piece 3l1a in the transverse direction can be fixed by means of a holding device 32 up to a holding force exerted by the holding device 32 in the activated state. The holding device has at least one electrical actuator 32a, by means of which the holding device is adjusted between its passive state (open state), in which the displacement of the center piece 31a is released, and its activated state (closed state), in which a holding force is exerted on the center piece will. The holding device 32 is here on

attached to one of the bearing legs 10b.

A momentary angular position of the wheels 11 can thus be determined with a holding force by means of the holding device 32 . This can be advantageous if one of the electric motors 15 fails. The holding force can only be chosen so large that even in the closed state of the holding device 32 by means of sufficiently high driving and/or braking forces, an adjustment of the

current angular position of the wheels 11 can be achieved.

The wheels 11 are steered, ie the angular position of the wheels 11 about the pivot axes 14 is adjusted, as already mentioned several times, only by means of drive and/or braking forces. There is therefore no steering mechanism by which the rotation of a steering wheel is mechanically transmitted to the angular position of the wheels. There are also no additional steering actuators which are not used to drive the wheels about the wheel axles 13 but only to actively adjust the angular position of the wheels about the pivot axes

14 serve.

A steering of the wheels only by means of drive and braking forces is already known in principle and does not have to be explained in detail within the scope of this document. An electrical control device used for this purpose is not shown, and this is generally not part of the platform either. Are not shown, apart from the electric motors for the individual wheel drives and the other actuators 28, 32a described other parts of the electrical equipment, such as electrical lines and sensors, such as sensors for detecting the

Angular position of the wheel carriers 12 about the pivot axes 14.

A second embodiment of the invention is in

Explained below with reference to FIGS. 11 to 14. Hereinafter

the differences from the first exemplary embodiment are essentially described. Unless otherwise described, the design corresponds to that of the first exemplary embodiment and the description of the first exemplary embodiment and possible modifications thereof

can be used accordingly.

In contrast to the first exemplary embodiment, in this second exemplary embodiment there is only a single left and a single right trailing arm 21'. Like the lower trailing arms 21, these trailing arms 21' are mounted on the base unit 10 so that they can pivot about transverse axes 22, their pivoting being cushioned by torsion bar springs 26 in the same way as in the first exemplary embodiment. To dampen the pivoting, telescopic dampers are provided as dampers 19', which act between the respective trailing arm 21' and the base unit 10. Instead of this

rotary dampers could also in turn be provided.

The wheel carriers 12 are here on the respective individual trailing arm 21' about the respective pivot axis 14

pivoted.

A holding device 32', which interacts directly with the respective wheel carrier 12, is used here to determine the current angular position of the wheels 11 about the respective pivot axis 14. The holding device has a brake part 32'''b which fixes the pivot position of the respective wheel carrier 12 about the respective pivot axis 4,

which is actuated by a respective actuator 32'a. However, analogously to the first exemplary embodiment, the holding device could again be connected to the connecting rod 31

work together.

A third embodiment of the invention is shown in Figs. 15-17. The difference compared to the second exemplary embodiment consists in the type of damping of the pivoting of the respective trailing arm 21'. The upward and downward movement of the trailing arms 21' is here converted into a horizontal movement in the transverse direction by means of toggle levers 33, this movement of the toggle levers 33 being damped by means of linear dampers 30'', which are arranged in the transverse direction and between the upward direction Legs of the respective toggle lever 33 and the base unit 10 act. Such an arrangement has advantages

with regard to the space required.

Various further modifications of the shown exemplary embodiments of the invention are conceivable and possible without departing from the scope of the invention as defined in the claims. For example, the wheel suspension for the steerable wheels could be designed in different ways. Instead of a trailing arm suspension, another type of suspension could also be used, for example a McPherson suspension, a double wishbone suspension or a

Wheel suspension by means of a rigid axle.

Instead of the rear axle module 3 shown with non-steerable wheels, a rear axle module with steerable wheels could also be used, with these wheels also being steered only by means of drive and/or braking forces. For example, the rear axle module

be designed in a similar way to the front axle module.

It could also have more than one front axle module with steerables

Wheels may be present and/or there could be more than one

rear axle module with non-steerable wheels or steerable

wheels are present.

20 21, 22 23 24

19

Legend

to the reference numbers:

Chassis module Platform base Front axle module Rear axle module Rigid axle Leaf spring package Base unit Screw

wheel

Suspension and/or damping element, base unit, leg, bearing leg

wheel

Wheel carrier Wheel axle Swivel axle Electric motor Brake disc Brake caliper Screw Suspension and/or damping element Trailing arm

21) Trailing arm lower transverse axle lower transverse axle

upper transverse axis

25 upper transverse axis 26 torsion bar spring

27 holding part

28 actuator

29 connecting piece 30, 30', 30'' damper 31 connecting rod 31a center piece

31b side piece

31c side piece

32, 32' holding device 32a, 32'a actuator 32'b braking part

33 toggle levers

Claims (3)

20 patent claims 1. Platform for at least four-wheel motor vehicles with an electric drive, comprising at least one front and at least one rear axle group, which are spaced apart from one another in a longitudinal direction of the platform and of which at least the front axle group has wheels (11) that can be steered about a respective pivot axis (14), which are mounted on wheel carriers (12) so that they can rotate about wheel axles (13) and are driven individually by electric motors (15), the wheel carriers (12) which can be pivoted about the pivot axes (14) being connected to one another via a connecting rod (31) and the steering of the wheels (8) takes place only by means of drive and/or braking forces, characterized in that the platform is of modular design and has a chassis module (1) and a front axle module (2) forming the front axle group, which as a whole is connected to the chassis module (1) connectable and dated Chassis module (1) is removable. 2. Platform according to claim 1, characterized in that the front axle module (2) by means of a screw connected to the chassis module (1). 3. Platform according to claim 1 or 2, characterized characterized in that the front axle module (2) a has a rigid base unit (10) via which in with the chassis module (1) connected state of the front axle module (2) is connected to the chassis module (1) and attached to which the wheel suspension is. Platform according to Claim 3, characterized in that the wheels (11) of the front axle module (2) are suspended via a trailing arm wheel suspension which has at least one left and at least one right trailing arm (20, 21, 21'), each with the base unit (10) about a transverse axis (24, 22) are pivotally connected, wherein the wheel carrier (12) with the trailing arms (20, 21, 21 ') to the respective Pivot axis (14) are pivotally connected. Platform according to Claim 4, characterized in that an upper and a lower trailing arm (20, 21) are provided both for the left wheel (11) and for the right wheel (11), which support the wheel carrier assigned to the respective wheel (11). (12) by type a Store the parallelogram guide so that it can pivot. Platform according to Claim 4 or 5, characterized in that at least one torsion bar spring (26) assigned to the at least one left trailing link (21, 21') and at least one torsion bar spring (26) assigned to the at least one right trailing link (21, 21') for suspension the pivoting of the respective trailing arm (20, 21') about the respective transverse axis (22) relative to the base unit (10) are provided. Platform according to claim 6, characterized in that the torsion springs (26) coaxial to the respective 11. 22 Transverse axis (22) are arranged, around which the respective trailing arm (21, 21'), to which the respective torsion bar spring (26) is connected, can be pivoted, with these transverse axes (22) relative to the Longitudinally offset from the platform to each other. Platform according to Claim 7, characterized in that the respective torsion bar spring (26) is held in a non-rotatable manner by a holding part (27) in a region spaced from the connection to the respective trailing arm (21, 21') which, in relation to the axis parallel to the transverse axis ( 22) lying transverse direction is displaceably connected to the torsion bar spring (26) and which on the base unit (10) of the axle module (2) in the Transverse direction is adjustable. Platform according to Claim 8, characterized in that the holding part (27) can be moved in the transverse direction relative to the base unit (10) by means of an actuator (28). is movable. Platform according to one of Claims 1 to 9, characterized in that the respective angular position of each of the steerable wheels (11) of the front axle module (2) about the respective pivot axis (14) by means of a holding device (32, 32') with a holding power can be determined. Platform according to Claim 10, characterized in that to determine the angular position of the respective steerable wheel (11) with the holding force, the holding device (32, 32') is connected to the connecting rod (31) or to the respective wheel carrier (12) works together. 13. 14 15 23 Platform according to one of Claims 1 to 11, characterized in that the connecting rod (31) has a center piece (31a) which is mounted on the base unit (10) of the axle module (2) so that it can be displaced in the transverse direction and has side pieces (31b, 31c). Which with the center piece (31a) and with the respective Wheel carrier (12) are articulated. Platform according to one of Claims 1 to 12, characterized in that the platform also has a rear axle module (3) forming the rear axle group. having. Platform according to one of claims 1 to 13, characterized in that the caster angle is 0° or is negative. Platform according to any one of claims 1 to 14, characterized characterized in that the spread is 0° or is negative.