WO2008151401A1

WO2008151401A1 - Clutch plateau, clutch plateau housing, process for manufacturing a clutch plateau, clutch system and vehicle

Info

Publication number: WO2008151401A1
Application number: PCT/BR2008/000169
Authority: WO
Inventors: Ricardo Vera Torres
Original assignee: ZF do Brasil Ltda
Current assignee: ZF do Brasil Ltda
Priority date: 2007-06-14
Filing date: 2008-06-16
Publication date: 2008-12-18
Anticipated expiration: 2009-12-14
Also published as: BRPI0702601A2; AR067031A1

Abstract

The present invention relates to a vehicle clutch system having a clutch plateau whose housing (1) has a substantially annular shape and defines at least a preferably concentric and circular opening (2), said housing being composed of at least one linearly elongated strip (3), annularly formed in one or more segments.

Description

Title: "CLUTCH PLATEAU, CLUTCH PLATEAU HOUSING, PROCESS FOR MANUFACTURING A CLUTCH PLATEAU, CLUTCH SYSTEM AND VEHICLE"

The present invention relates to a plateau, particularly a clutch system plateau used in land vehicles, which exhibits educed manufacturing costs and efficient operation. The present invention further relates to a clutch plateau housing, to the process for manufacturing said clutch plateau, to a clutch system comprising said clutch plateau, and to a land automotive vehicle equipped with at least one said clutch plateau and one said clutch system.

Description of the Prior Art

Land automotive vehicles, such as light commercial automobiles, transportation vehicles, buses and agricultural machines, among others, have a transmission system which transmits motion from the engine to the driving wheels, multiplying or demultiplying the power according to the need. As a general rule, the transmission system comprises at least one gearbox, at least one differential, drive shafts or semi-shafts and at least one clutch system.

The clutch system comprises a plurality of components positioned between the engine and the gear of the vehicle, so as to selectively enable or prevent the transmission of engine rotations to the gearbox, and consequently to the differential, semi-shafts and driving wheels.

The most commonly used known clutch system, especially in passenger vehicles and light commercial vehicles, is referred to as the dry monodisc system, and essentially comprises a disc, a clutch plateau and an actuation system.

The disc is directly responsible for transmitting torque from the engine to the gearbox of the vehicle. To this end, it comprises a first portion in the form of an outer ring, having a friction material which cooperates with a circular flywheel associated with the crankshaft, and a second central portion, having a knurled or splined hole which cooperates with the pilot or primary shaft of the gearbox of the vehicle.

When the disc touches the flywheel, its friction material rubs against the corresponding surface of the flywheel, which moves the disc with its angular movement. The disc, in turn, moves the primary shaft of the gearbox, which is fitted to its central knurled or splined hole.

For the friction between the disc and the flywheel to be sufficient to move the vehicle without causing the components to slide against each other, the aforementioned clutch plateau and actuating spring are provided. The clutch plateau is a set of components, with a substantially circular appearance, among which the most important are the pressure plate, one or more springs and the housing. The pressure plate is substantially ring- shaped, and through the force exerted by the spring(s) it presses the disc against the flywheel, increasing the friction force component.

The clutch operates in such a way that the spring(s) normally press(es) the pressure plate against the disc, which in turn is pressed against the flywheel, transmitting the torque. In other words, the clutch at rest enables the transmission of torque from the engine to the transmission.

For the transmission of torque from the engine to the gear to cease, the disc must be pulled away from the flywheel, ceasing its angular movement. To this end, the actuating system of the clutch should be manipulated, which corresponds, in most cases, to a pedal which, when pressed, moves a fork which overcomes the elastic force exerted by the spring(s), pulling the pressure plate away from the clutch plateau. While the pedal is pressed, the pressure plate is kept away from the disc. As soon as the force exerted on the pedal ceases, the force of the spring(s) prevails again and the pressure plate is once again pressed against the disc, which in turn is pressed against the flywheel. The movement of the pedal is transmitted to the fork by means of cables or of an oildynamic circuit.

Some vehicles use an electrical clutch actuating system, where the pedal is substituted with a servomotor which directly actuates the clutch fork.

A large majority of current clutch systems use a single _

diaphragm spring. The diaphragm consists of a conical spring with slots radiating from its center (concentric slots). The spring is almost flat-mounted, so that when it tries to regain its original shape, it exerts a uniform pressure along its edges, which are on the pressure plate. The thrust ring acting on the diaphragm makes it bend, releasing the pressure plate to press the disc against the flywheel.

The clutch plateau further comprises a cover or housing which has a structural function and encloses the other components. This housing is usually made of steel and has the shape of an annular plate which defines two main surfaces, which are substantially circular and have a concentric opening, which is also circular. The purpose of the opening is to enable the correct positioning of the primary shaft of the gearbox.

In the dry monodisc clutch systems known nowadays, the clutch plateau housing is formed by stamping and subsequent finishing and sizing operations. A circular sheet is taken and, by stamping or punching the cylindrical cross section, the central portion of the sheet is extracted, forming, at the same time, said circular concentric opening and other characteristic folds and holes of the housing.

This stamping operation, although not expensive in itself, leads to a considerable waste of raw-material, since all the material portion removed from the circular sheet to form the concentric opening is discarded and no longer used in the clutch manufacturing process.

Until the present moment, there had been no development of a clutch plateau manufactured so as to minimize steel waste (thereby reducing its manufacturing cost) without loss of performance and functionality. Object of the Invention

The object of the present invention is to provide a clutch plateau, notably for use in a vehicle dry monodisc clutch system, having a reduced manufacturing cost due to the reduced amount of material (usually steel) required for the manufacture thereof, without loss of performance and/or functionality.

Additionally, the present invention aims at providing a clutch plateau having a housing which, due to the reduced amount of raw material required for its manufacture, is more advantageous in terms of environmental impact, reducing the amount of waste material which needs to be discarded or reprocessed to be used at a later time. The present invention further aims at providing a clutch plateau housing which requires less material to be produced, resulting in a cheaper and more advantageous manufacture in terms of environmental impact, without loss of performance and/or functionality.

A further object of the present invention is a process for manufacturing a clutch plateau which enables the reduction of the amount of raw material required for said manufacture, without altering its performance and/or functionality.

Yet another object of the present invention is a clutch system comprising the aforementioned clutch plateau. Finally, a further object of the present invention is a land automotive vehicle equipped with at least one said clutch plateau and one said clutch system. Brief Description of the Invention

The objects of the present invention are achieved by a clutch plateau, particularly for use in a clutch system of a vehicle, having a housing of substantially annular shape and which defines at least a preferably concentric and circular opening, said housing being composed of at least one linearly elongated, annularly formed strip.

The objects of the present invention are also achieved by a clutch plateau housing, having a substantially annular shape and defining at least a preferably concentric and circular opening, which is composed of at least one linearly elongated, annularly formed strip.

Additionally, the objects of the present invention are achieved by a process for manufacturing a clutch plateau, specifically for manufacturing a clutch plateau housing, comprising the following steps:

- step (i): obtaining at least one linearly elongated strip, having a first main end and a second main end, opposed to the first one; - step (ii): annularly forming the strip or strips; and

- step (iii): weld joining the first and second ends of the strip or strips, thereby forming the housing.

Finally, the objects of the present invention are achieved by a vehicle clutch system and a vehicle, particularly a land automotive vehicle, comprising at least a clutch plateau as defined in the claims.

The present invention has the following advantages, among others:

(i) reduction of the manufacturing cost of the clutch plateau through the reduction of waste material which cannot be reused in the process for manufacturing the clutch;

(ii) reduction of environmental liabilities and of waste material which must be reprocessed, generating an economy of natural resources and money, in addition to a reduced environmental impact; and (iii) reduction in the manufacturing cost while maintaining the performance and functionality of the clutch plateau, without any loss to the user. Brief Description of the Drawings

The present invention will be described in more detail below, based on an example of execution represented in the drawings:

Figure 1 - corresponds to a schematic perspective view of a generic dry monodisc clutch system clutch plateau;

Figure 2 - corresponds to a first schematic view of the process for the manufacture of a prior-art clutch plateau housing; Figure 3 - corresponds to a second schematic view of the process for the manufacture of a prior-art clutch plateau housing;

Figure 4 - corresponds to a third schematic view of the process for the manufacture of a prior-art clutch plateau housing;

Figure 5 - corresponds to a schematic view of a first possibility of the process for the manufacture of the clutch plateau housing of the present invention in a first instance;

Figure 6 - corresponds to a schematic view of the first possibility of the process for the manufacture of the clutch plateau housing of the present invention in a second instance;

Figure 7 - corresponds to a schematic view of the first possibility of the process for the manufacture of the clutch plateau housing of the present invention in a third instance;

Figure 8 - corresponds to a schematic view of the first possibility of the process for the manufacture of the clutch plateau housing of the present invention in a fourth instance;

Figure 9 - corresponds to a schematic view of the first possibility of the process for the manufacture of the clutch plateau housing of the present invention in a fifth instance;

Figure 10 - corresponds to a schematic view of the first possibility of the process for the manufacture of the clutch plateau housing of the present invention in a sixth instance; Figure 11 - corresponds to a perspective view of the clutch plateau housing of the present invention obtained through the first possibility of the manufacturing process;

Figure 12 - corresponds to a schematic view of a second possibility of the process for the manufacture of the clutch plateau housing of the present invention in a first instance, when the forming of the elongated strip is made by calendering;

Figure 13 - corresponds to a schematic view of the second possibility of the process for the manufacture of the clutch plateau housing of the present invention in a second instance, when the forming of the elongated strip is made by calendering;

Figure 14 - corresponds to a schematic view of the second possibility of the process for the manufacture of the clutch plateau housing of the present invention in a third instance, when the forming of the elongated strip is made by calendering; Figure 15 - corresponds to a schematic view of a second possibility of the process for the manufacture of the clutch plateau housing of the present invention in a first instance, when the forming of the elongated strip is made by stamping;

Figure 16 - corresponds to a schematic view of the second possibility of the process for the manufacture of the clutch plateau housing of the present invention in a second instance, when the forming of the elongated strip is made by stamping;

Figure 17 - corresponds to a schematic view of the second possibility of the process for the manufacture of the clutch plateau housing of the present invention in a third instance, when the forming of the elongated strip is made by stamping; Figure 18 - corresponds to a schematic view of the second possibility of the process for the manufacture of the clutch plateau housing of the present invention in a fourth instance;

Figure 19 - corresponds to a schematic view of the second possibility of the process for the manufacture of the clutch plateau housing of the present invention in a fifth instance;

Figure 20 - corresponds to a schematic view of the second possibility of the process for the manufacture of the clutch plateau housing of the present invention in a sixth instance; and

Figure 21 - corresponds to a perspective view of the clutch plateau housing of the present invention obtained through the second possibility of the manufacturing process. Detailed Description of the Drawings

The clutch systems used in land vehicles enable the gradual equalization between the rotation of the crankshaft of an internal combustion engine and the wheels of a vehicle, through the transmission system

(gearbox, differential, semi-shafts, etc.). To this end, a clutch disc connected directly to the pilot shaft of the gearbox (not illustrated) is provided, which can be coupled to the flywheel (also not illustrated), which is a circular part connected to the crankshaft and which rotates simultaneously with it. In general, the disc is maintained pressed against the flywheel by means of a diaphragm spring, or by means of a plurality of helical springs; however, this latter solution is outdated and desuete. A generic clutch system, of the dry monodisc type, is illustrated in figure 1 , with its main constituent components, namely: housing 100, disc (not illustrated), diaphragm spring 300, pressure plate 400, engagement fork/roller bearing 500 and sealing rings/seal retainers 600. The usual operation condition of a clutch system maintains the engine and the gear mechanically connected, since the pressure exerted by the diaphragm spring 300 on the pressure plate 400, pressing it against the disc, generates sufficient friction force between the flywheel and the disc for the torque to be transmitted from the former to the latter. In order to define the required and sufficient friction force between them, the surface of the disc rubbing against the flywheel is coated with a material having known roughness/friction coefficient, such as, for example, sintered material sheets.

When the rotation of the engine needs to be decoupled from the rotation of the powertrain (for example, when the vehicle is at rest, with the engine running and the transmission in gear), the clutch disc must be pulled away from the flywheel, which, in general, is made by actuating a pedal called clutch pedal (not illustrated).

Similarly, it is necessary to couple the disc and the flywheel when the vehicle starts to be put in motion after a gear is engaged in the gearbox. In order to prevent jolting, the coupling between the disc and the flywheel in these situations should be progressive, meaning that the rotation of the engine and of the transmission should be leveled gradually, which increases the comfort in the use of the vehicle and the durability of the components of the powertrain.

When the clutch pedal is actuated by means of a cable or of a hydraulic circuit, it moves the actuating fork 500, which overcomes the force exerted by the diaphragm spring 300 and effects said separation. The system is kept in this state until the pedal is released and the diaphragm spring 300 goes back to pressing the disc against the flywheel.

Nowadays, automatic microprocessed clutch actuating systems have been developed, which substitute the pedal with oildynamic or electric circuits which make the coupling and decoupling between the disc and the flywheel. In any case, with the exception of the actuating manner, the clutch system itself does not present significant differences compared to the manually actuated ones. Now that the basic operation of the dry monodisc clutch system has been explained in its essence, a more detailed description of its most important components should be provided.

The clutch disc has a substantially circular shape and comprises a first portion in the form of an outer ring, having a friction material which cooperates with a circular flywheel associated with the crankshaft, and a second central portion, having a knurled or splined hole which cooperates with the pilot or primary shaft of the gearbox of the vehicle. Preferably, the disc further comprises a first and a second vibration damping system to attenuate the torsion vibrations generated by the engine in the transmission. It should be noted, however, that the specific constitution of the disc is irrelevant in the present case, and that it may have any of many different configurations without causing the resulting invention to be outside the scope of protection of the claims.

Analogously, the retainers 600, the engagement fork 500 and the other accessory components may vary immensely as to their characteristics, since they are also not included in the scope of protection of the claims.

The spring 300, as previously mentioned, is preferably of the diaphragm type. The diaphragm spring 300 is substantially conical and has slots radiating from its center (concentric slots). The spring 300 is almost flat- mounted, so that when it tries to regain its original shape, it exerts a uniform pressure along its outer perimeter, which is on the pressure plate 400. The thrust ring acting on the spring 300 makes it bend, releasing the pressure plate 400 and consequently separating the disc from the flywheel.

This system is preferred nowadays due to the need to occupy less and less space in the engine compartment (the clutch plateau with the diaphragm spring has a very reduced thickness, which is very important for compact vehicles) and enables the use of light weight mechanical components, minimizing the resistance to the engine rotation, resulting in lower mechanical loss.

The shape, performance and functionality of the improved clutch plateau, which is the main innovation of the presently disclosed clutch system, are analogous to those of the prior-art clutch plateaus; however, its housing 1 is obtained with less material waste and with reduced cost, due to its groundbreaking concept and to the use of an innovative manufacturing process.

The whole housing has a substantially annular shape, defining a preferably concentric and circular opening to enable the correct positioning of the primary shaft of the gearbox. Preferably, the housing is made of steel, but it is evident that it can be made of any other required or desirable material.

In the prior-art housings 100, illustrated in figures 1 and 4, the annular shape is obtained by stamping a preferably substantially circular steel sheet illustrated in figures 2 and 3. By means of a die or a punch, illustrated as P in figure 3, the concentric opening 55 is made, and the piece of material corresponding to the opening is discarded. If the housing is made of steel, the discarded steel can be reused if sent to locations specifically intended for this purpose, but it is not used in the housing manufacturing process anymore. Since the area of the opening 55 for obtaining the housing is considerable in relation to the total area of the steel sheet 50, the waste of raw material is also relevant and inconvenient.

This considerable waste of raw material increases the manufacturing costs of the prior-art clutch plateau in many ways:

(a) Firstly, there is a need to buy a certain amount of excess raw material, a considerable part of which will never be used in forming the clutch plateaus;

(b) Secondly, there is the logistic cost of gathering, storing and sending said raw material for recycling or disposal, including all the correlated operations.

(c) Finally, there is the indirect cost for society and for the environment, resulting from the need to dispose of the waste raw material or to recycle it.

The clutch plateau of the present invention does not lead to any kind of considerable raw material waste, since its housing is not produced by stamping from a single piece.

A first embodiment of the clutch plateau of the present invention has a housing 1 formed by calendering of a steel strip. But essentially speaking, this first embodiment of the clutch plateau of the present invention also has a housing 1 having a substantially annular shape and which defines at least one preferably concentric and circular opening 2; however, the housing is composed of a linearly elongated, annularly formed strip 3.

The elongated strip 3 has a total length such that, after formed by calendering to assume an annular shape, it forms exactly the housing 1 , without the need for punching to obtain the central opening, and therefore without considerably cutting/removing material.

The strip 3 preferably has a substantially elongated shape, and defines a first main end 4 and a second main end 5, opposed to the first one, which can be seen in detail in figures 5 to 8.

For the manufacture of the housing 1 , the strip 3 passes between a pair of rollers in an equipment called calender, representatively illustrated by two parallel, spaced apart spheres. As the strip 3 passes through the space between the two spheres, an axial force (represented by arrow F in the figures) is applied thereto, permanently deforming it. As a result, the strip 3, as it passes through the calender, assumes a curvilinear shape. Once the strip 3 has completely passed through the calender, it has been formed into a ring, so that the first and the second main ends 4,5 of the strip are substantially adjacent to each other (see figure 8). Evidently, the length of the strip 3, the speed with which it passes through the calender and the force F exerted on said strip are determined so as to obtain the ring- shaped form with the main ends adjacent to each other.

Subsequently, the first and second main ends 4,5 of the strip are joined by welding, thus forming the housing 1 itself. Still preferably, the area of the weld is machined for surface homogenization.

Optionally, after the welding and machining processes, the housing 1 undergoes stamping to form the folds and/or sizing, in which steps no loss of material occurs that is not negligible (see figure 10). The finished housing is illustrated in figure 11.

Although the housing 1 is preferably made of carbon steel, it is evident that it can be made of any other required or desirable material.

A second embodiment of the clutch plateau of the present invention exhibits the housing 1 composed not only of a single calendered strip 3, but of two or more strip segments which are formed (assuming the shape of parts of rings) and welded so as to form the housing 1 , which therefore has as many welds as the number of strip segments 3 forming it. In this case, it can be essentially said that the housing 1 is composed of two or more linearly elongated, annularly formed strips 3, each of which constitutes a strip segment, in which the annular strip segments are adjacently joined to each other so as to form the housing 1.

Each segment of the linearly elongated strip 3 comprises a first main end and a second main end, opposed to the first one, joined together, after the calendering process, by welding. After all the welding has been carried out, this housing 1 also undergoes stamping to form the folds and/or sizing, in which steps no loss of material occurs that is not negligible (see figure 20). An example of a housing formed by four strip 3 segments is illustrated in figure 21 , but it is evident that this number may be higher or lower, if required or desirable. In case several strip segments formed to produce the housing 1 are used, it is important to note that these segments may be formed by calendering or by stamping (where they will be formed without producing a large amount of scrap, since there is no need to form an opening).

Another inventive and novel invention is the process for manufacturing a clutch plateau, specifically the manufacturing of the clutch plateau housing 1 , which comprises the following steps:

- step (i): obtaining at least one linearly elongated strip 3, having the o

first main 4 end and the second main end 5, opposed to the first one;

- step (ii): annularly forming the strip or strips; and

- step (iii): joining the first and second ends 4,5 of the strip or strips 3 by welding 6, thereby forming the housing 1. Preferably, though not necessarily, the process comprises a step

(iv) of stamping for forming the folds and/or sizing, but no loss of material which is not negligible occurs, since the purpose of said forming is merely to give the part its final measurements, with the sizing of the important dimensions. Also preferably, the process further comprises a step (v) of machining the clutch plateau in the area of the weld(s) 6.

In order to obtain the first embodiment of the clutch plateau, there is a first possibility of the manufacturing process (schematically illustrated in figures 5 and 10), in which step (i) corresponds to obtaining a single linearly elongated strip 3. In this case, step (ii) corresponds to annularly forming the single strip 3 by calendering until the first and the second ends 4,5 are adjacent, and may correspond to a single procedure or to several successive calendering sub-steps, each gradually and successively forming the strip 3, until the ring shape is reached. For the sake of illustration only, in the drawings, step (ii) is shown in figures 6 and 7 as a single step.

In order to obtain the second embodiment of the clutch plateau, there is a second possibility of the manufacturing process (schematically illustrated in figures 12 and 20), in which step (i) corresponds to obtaining two or more linearly elongated, annularly formed strips 3, each constituting a strip segment, and in which step (ii) corresponds to annularly forming said two or more strip segments by calendering (figures 12 to 14) or by stamping (figures 15 to 17).

A further inventive and novel invention, included in the scope of protection of the attached claims, is a vehicle clutch system, particularly, but not necessarily, a clutch system of the dry monodisc type, characterized by comprising, among other components (such as a disc, an engagement fork, an actuating system, etc.), at least one clutch plateau 1 as defined above.

Finally, another inventive and novel invention included in the scope of protection of the attached claims is a vehicle, particularly a land automotive vehicle, which comprises at least one clutch plateau 1 as defined above.

Having described an example of a preferred embodiment, it should be understood that the scope of the present invention embraces other possible variations, and is limited only by the content of the appended claims, including therein the possible equivalents.

Claims

1. A clutch plateau, particularly for use in a clutch system of a vehicle, having at least a housing (1 ) of substantially annular shape and which defines at least a preferably concentric and circular opening (2), characterized in that said housing (1 ) is composed of at least one linearly elongated, annularly formed strip (3).

2. A clutch plateau according to claim 1 , characterized in that the housing (1 ) is composed of two or more linearly elongated, annularly formed strips (3), each of which constitutes a strip segment, in which the annular strip segments are adjacently joined to each other so as to form the housing

(1 ).

3. A clutch plateau according to claim 1 , characterized in that the linearly elongated strip (3) is annularly formed by calendering.

4. A clutch plateau according to claim 2, characterized in that each linearly elongated strip segment is annularly formed by calendaring or stamping.

5. A clutch plateau according to claim 3, characterized in that the linearly elongated strip (3) comprises a first main end (4) and a second main end (5), opposed to the first one, joined together, after the calendering process, by welding (6).

6. A clutch plateau according to claim 4, characterized in that each linearly elongated strip segment comprises a first main end and a second main end, opposed to the first one, joined together, after the calendering process, by welding.

7. A clutch plateau housing, having a substantially annular shape and defining at least a preferably concentric and circular opening (2), characterized by being composed of at least one linearly elongated, annularly formed strip (3).

8. A housing according to claim 7, characterized by being composed of two or more linearly elongated, annularly formed strips (3), each of which constitutes a strip segment, in which the annular strip segments are adjacently joined to each other. I D

9. A housing according to claim 7, characterized in that the linearly elongated strip (3) is annularly formed by calendering.

10. A housing according to claim 8, characterized in that each linearly elongated strip segment is annularly formed by calendaring or stamping.

11. A housing according to claim 9, characterized in that the linearly elongated strip (3) comprises a first main end (4) and a second main end (5), opposed to the first one, joined together, after the calendering process, by welding (6).

12. A housing according to claim 10, characterized in that each linearly elongated strip segment comprises a first main end and a second main end, opposed to the first one, joined together, after the calendering process, by welding.

13. A process for manufacturing a clutch plateau, specifically the manufacture of a clutch plateau housing (1 ), characterized by comprising the following steps:

- step (i): obtaining at least one linearly elongated strip (3), having a first main end (4) and a second main end (5), opposed to the first one;

- step (ii): annularly forming the strip or strips (3); and - step (iii): joining the first and second ends (4,5) of the strip or strips

(3) by welding (6), thereby forming the housing (1 ).

14. The process according to claim 13, characterized in that step (i) corresponds to obtaining a single linearly elongated strip (3).

15. The process according to claim 13, characterized in that step (i) corresponds to obtaining two or more linearly elongated, annularly formed strips (3), each of which constitutes a strip segment.

16. The process according to claim 14, characterized in that step (ii) corresponds to annularly forming the single strip (3) by calendering until the first and second ends (4,5) are adjacent to each other.

17. The process according to claim 15, characterized in that step

(ii) corresponds to annularly forming said two or more strip segments by calendering or stamping.

18. The process according to claim 13, characterized by comprising a step (iv) of stamping to form the folds and/or sizing, without any loss of material which is not negligible.

19. The process according to claim 13, characterized by comprising a step (v) of machining the clutch plateau in the weld (6) zone.

20. The process according to claim 13, characterized in that step (ii), of annularly forming the strip (3) by calendaring, may correspond to a single procedure or to several successive calendering sub-steps, each gradually and successively forming the strip (3), until the annular shape is reached.

21. A vehicle clutch system, particularly, but not necessarily, a clutch system of the dry monodisc type, characterized by comprising, among other components, at least one clutch plateau (1) as defined in claims 1 to 6.

22. A vehicle, particularly a land automotive vehicle, characterized by comprising at least one clutch plateau (1 ) as defined in claims 1 to 6.