PRIOR ART Sequential gearboxes which facilitate gear changes without using a separate clutch are previously known. Designs of this kind are previously known for example from US 5 000 057, US 2 660 899 and US 2 028 028. A common feature of all these known designs is that they are extremely complex in construction, which is explained amongst other things by the fact that it has been attempted to avoid the use of clutch mechanisms in which cog teeth or the like interact directly. Instead, solutions have been found which call for a number of different alternative clutch mechanisms, which has drastically increased the number of constituent elements. It is obviously a great disadvantage to have a large number of parts, both from the weight, cost and maintenance point of view.

In many vehicle sectors, however, a choice has been made to retain clutch mechanisms containing cog teeth and other solutions have been developed instead to be able to eliminate a separate clutch. A commonly applied solution is to use so-called"dog ring" gearboxes. A dog ring can be said to consist of a driving disc with cog teeth on the side which is intended owing to substantial"play"to interact rapidly with corresponding cog teeth on one of the gear wheels in the gearbox. Gearboxes of this kind are often used, for example, in connection with smaller engines, for example on mopeds and motorcycles. However, this principle is used in larger gearboxes also, where a large torque has to be transmitted, swift gear changes have to be able to be performed and low weight is important, e. g. in racing gearboxes in Formula 1, rallying etc. Gear changes can be performed very quickly by means of these so-called"dog ring"gearboxes. In today's elite context, it is usual for the driver not to have to release the throttle when changing gear, but for the engine to be automatically interrupted for a very short time on

each gear change. Carrying out gear changes has been successfully optimized by means of advanced electronics, resulting in extremely small time losses when the engine does not transmit any torque. However, it is understood that it would be desirable to be able to cut these time losses completely.

In the sport of drag racing,"dog ring"engineering has been developed so that on acceleration the next gear up can be engaged while the existing gear continues to be engaged. This means that changes up can be performed entirely without interrupting acceleration. Known gearboxes of this kind do not facilitate engine braking, however. It can be said that such a gearbox functions as a free wheel, when the torque around the output shaft changes direction. It is understood that a gearbox which does not facilitate engine braking can only conceivably be accepted in a very limited application area, such as drag racing for example. This is therefore a considerable disadvantage.

BRIEF ACCOUNT OF THE INVENTION The object according to the invention is to eliminate or at least minimize the aforementioned problems, which is achieved by means of a gearbox comprising an input shaft and an output shaft, arranged on which is a number of interacting gear wheel pairs, one of the gear wheels in the gear wheel pair being fixed if) relation to its shaft while the other gear wheel is disposed rotatably around its shaft and is fixed only in an axial direction, and a number of drivers which are arranged coaxially with said rotatable gear wheels, which drivers are arranged rotationally securely on said shaft but axially displaceable, interacting elements on the drivers and said rotatable gear wheels respectively facilitating the continuous transmission of torque from the input shaft via said driver and gear wheel pairs to the output shaft without any interruption in acceleration when changing up, at least one driver being provided with interacting elements on either side, intended to interact with corresponding interacting elements on adjacent gear wheels, so that a decelerating torque can also be transmitted from the output shaft to the input shaft.

Thanks to the solution according to the invention, the advantage is gained that changing up can take place entirely without interruption in acceleration, i. e. without any

interruption at the moment of changing up, at the same time as the design permits deceleration by means of engine braking. In addition, the design makes it possible to achieve less wear than according to the known"dog ring"technique, since the gear change mechanism results in less violent treatment of the meshing dogs. A further advantage of the design is that the soft gear change transitions on acceleration lead to the sound level remaining very low, i. e. the gearbox will cause less noise than that known in connection with many conventional"dog ring"gearboxes. As a further bonus, the soft gear change mechanism means that relatively small forces need to be used to move the meshing dogs into and out of engagement. Thanks to the advantages of a gearbox according to the invention, it can also be used advantageously for standard automatic gearboxes, since it permits a combination of low losses and the elimination of gearshift interruption, producing a high level of efficiency, while at the same time facilitating better control/optimization of combustion, i. e. minimized exhaust discharge.

According to further aspects of the invention -said interacting elements comprise meshing surfaces for deceleration or acceleration respectively and also at least one inclined surface to be able to act on at least one driver with a disengaging transverse force, said inclined surface preferably being disposed below in relation to at least one meshing surface intended for acceleration, -said inclined surface interacts with at least one inclined surface disposed on the adjacent driver or gear wheel, which are arranged essentially parallel in relation to one another, -said driver is positioned by means of at least one shift fork, which at one end has interacting elements for the driver, and at its other end has elements interacting with a shift fork control device, it being possible to adjust the position of the driver, -said elements interacting with the fork control device comprise a mechanism with at least one control device, which during the greater part of its interaction is positively controlled in both transverse directions inside said shift fork control device, there being at least one zone A-B during which positive control does not take place, but certain play exists,

-said positive control is achieved by means of tracks, preferably in a drum, and control devices, which are fixedly arranged at one end of said shift fork, and a limited extent of said tracks has an increased width compared with the width otherwise existing in the track, -said elements interacting with the shift fork control device comprise a mechanism which is positively controlled in one direction and is movable to a limited extent against a spring force in the other direction, -said mechanism comprises a pin-shaped element which is disposed inside a recess in one end of said shift fork, which element is pressed in one direction inside said recess by means of a spring element and said shift fork control device being provided at least one track, inside which track one end of said element is disposed to move and thereby be capable of being moved in an axial direction, which leads to movement of the shift fork and driver, -the gearbox comprises at least two drivers, which can be engaged on either side with one and the same gear wheel at the same time, the gearbox preferably comprising the same number of drivers as the number of interacting gear wheel pairs for forward gear changing, -the meshing surfaces of one side are disposed at a certain angle, so that on engagement they give rise to a retaining force, so that the driver and gear wheel remain engaged in connection with the transmission of torque, α preferably being between 0-10°.

BRIEF DESCRIPTION OF DRAWINGS The invention will be explained below in greater detail with reference to the enclosed drawings, in which: Fig. 1 shows an outline drawing of how a gearbox according to invention functions, Fig. 2 shows a side view of a preferred embodiment of a gearbox according to the invention, Fig. 3 shows the gearbox according to Fig. 2 in section along the line A-A, Fig. 4 shows a view from the front of a gear wheel on the input shaft, Fig. 5 shows said gear wheel seen from the side,

Fig. 6 shows said gear wheel seen from the back, Fig. 7 shows a driver seen from the front, Fig. 8 shows a driver seen from the side, Fig. 9 shows a driver seen from the back, Fig. 10 shows a modified and preferred embodiment of a shift fork interacting with a gear drum, Fig. 11 shows a multiplicity of shift forks arranged beside one another, Fig. 12 shows a preferred embodiment of an output shaft provided with cog wheels and drivers, and Fig. 13 shows tracks in the gear drum in expanded form.

DETAILED DESCRIPTION Figure 1 shows the principles of how a gearbox according to the invention works and briefly describes its function and advantages. The gearbox consists of an input shaft 10 with four gear wheels 12,14,16,18. In parallel to the input shaft 10 is an output shaft 20, arranged on which are also four gear wheels 1,2,3,4. The gear wheels on the upper shaft are mounted fixedly on this shaft, while the gear wheels on the output shaft 20 are disposed joumalled in bearings around this shaft 20. The gear wheels are constantly engaged in one another in such a way that different desired gear changes are obtained, the numbering of the gear wheels corresponding to the respective gear, i. e. when 1 is engaged and driving, the lowest speed is obtained on the output gear, while 4 gives the maximum output speed on the output shaft. Arranged on either side of gear wheels 1,2, 3,4 on the output shaft 20 are drivers 22,24,26,28,30. It is shown in the figure that arranged on each driver, at least on one side, is a circular ring with cog teeth 32,34 (also called dogs). Arranged also in a corresponding manner on each gear wheel 1,2,3, 4 on either side is a corresponding circular arrangement with cog teeth 32'and 34' respectively. Each gear wheel has cog teeth 34'on one side with straight (a = 0) meshing surfaces and on the other side cog teeth 32'with meshing surfaces cut at an acute angle (a is between 0-10°). In a similar formulation, but in a reversed manner, the drivers are provided with their cog teeth 32,34. The drivers 22-30 are disposed on the output shaft 20 by means of splines, so that they are radially fixed but movable in an axial direction. The drivers can be moved by means of shift forks 36-44. The position of

the forks is controlled by means of control pins 46, which are disposed in tracks 48,50, 52,54,56, which tracks are arranged in the surface of a shift fork control device 58, in the form of a gear drum, which can be rotated/pivoted by means of a gear shift bar (not shown). Disposed at the end of each shift fork is a spring 62 between one side of it and the control pin 46, so that a pressure force is achieved against the shift fork, which presses it to the right in the picture. Furthermore, located in the lower end 38 of the shift fork is an oblong hole 62, which facilitates movement of the shift fork in a lateral direction (to the left in the picture) in a direction which compresses the spring 60.

The gearbox functions so that when the gear lever is moved, the gear drum/ manoeuvring element 58 also moves, the control pins 46 for the forks and with them the two drivers 22,24, which sit on either side of first gear's gear wheel pair 1,18, are being moved in towards the gear wheel 1 by means of tracks 54,56. The transmission of force from the shift fork 36 to the driver takes place by means of y-shanks 37A, 37B, which enclose the outer edge 25 of the driver. When the manoeuvring element 58 is rotated so that the control pins are located on the line marked by a 1, the cog teeth 32, 32'and 34,34'respectively will be engaged. In connection with acceleration (see direction of rotation on input and output shaft respectively), the cog teeth 32,32'will transmit force from the input gear wheel 1, which force is transmitted from the input shaft 10 via the gear wheel 18, to the output shaft 20 thanks to the arrangement and direction of rotation of the teeth. The teeth 34,34'on the other side of the gear wheel 1 will only be actively engaged in connection with any deceleration, when a transmission of force in the opposing direction is obtained. In this way, a gear mechanism is thus obtained which minimizes wear and is without undesirable noise. The bevel-cut a meshing surfaces of the acceleration dogs can be advantageous in certain executions, since on acceleration they provide a uniting force between gear wheel and driver.

When a higher gear is to be engaged, the manoeuvring element 58 is turned a stage further in the same direction as before, the left-hand driver 24 first being moved out of first gear's gear wheel, since it is positively controlled by the fork 38 in that the control pin 46 is pressed directly against the edge of the hole 62, while the right-hand driver will remain engaged, as the control pin 46 for its fork 36 is only moved in the hole 60 to

compress the spring 62. The right-hand driver 22 will therefore remain engaged until its transmission torque ceases, which takes place as soon as the left-hand driver 24 engages in second gear's gear wheel. Changing up can thus take place continuously during full acceleration. On changing down, the gear lever is moved in the opposite direction, so that the manoeuvring element 58 rotates in the opposite direction. On changing down from second to first, for example, driver 24 between the gear wheels of first gear and second gear will be disengaged from the gear wheel 2 of second gear, following which the driver 22 arranged to the right of the gear wheel of first gear will move to engage with the accelerating tooth row 32,32', and the"decelerating"tooth row 34 on the driver 24 will be brought into engagement with the deceleration teeth 34'.

Figure 2 shows a preferred embodiment of a gearbox according to the invention. The basic construction is the same as described in Figure 1, but certain parts differ in execution. Amongst other things, it is shown that the input shaft 10 is provided with a further two forward gears 15,17 and a reverse gear 19. To optimize from the space point of view and reduce unnecessary weight, the input shaft 10 is provided with a rotationally symmetrical cavity 11. The output shaft 20 is also provided correspondingly with a cavity 21. The drivers 22,24 etc. are disposed in the same way as according to Figure 1, but instead of being provided with teeth on either side, there are instead teeth on one side and recesses on the other side, which will be explained in greater detail in connection with Figures 7,8 and 9. As in Figure 1, there is also a gear drum 58 provided with tracks 56,54 etc., which adjusts the position of the shift forks 36,38 etc. via control devices 46. Furthermore, it is shown that a spring 62 is used in the same way to press the control pin 46 in a given direction. The function is the same as for the arrangement already described in connection with Figure 1 and is not therefore described in greater detail.

Figure 3 shows selected parts of a driver 24 in cross-section, a plan view of a shift fork 36 and selected parts of the gear drum 58 in section. It is evident that the driver 24 is provided at its periphery with a track 25, inside which inwardly projecting elements 37A, 37B are arranged to be able to control the axial position of the driver 24. The upper part of the shift fork 36 is shaped like a U-shaped shank 36A, 36B, which

encloses roughly half the circumference of the driver 24. The U-shaped shanks 36A, 36B are joined at the bottom by a rod-shaped part 38. Inside this rod-shaped part, said control pin 46 is arranged pivotingly around an axis 45. The pin 46 is pressed constantly in one direction by means of a spring 60, which is arranged inside a cavity 62. The control pin 46 projects below the lower end part of the shift fork, where it runs inside a track 54 disposed on the periphery of the gear drum 58.

Figures 4,5 and 6 show various views of a gear wheel 1 according to a preferred execution according to the invention. Figure 4 shows a front view, which makes it clear that the gear wheel on this side is provided with recesses 32', which comprise a bevelled part 32A'and 3 last part 32B'and a right-angled upper surface 32C'. Figure 6 shows that the opposing side of the gear wheel 1 is provided with projecting tooth-like elements 34', which elements comprise an inclined part 34A', a flat part 34B'and a meshing surface 34C', which can be inclined. Normally around 4-8 teeth are used on each side. The distance/intermediate spacing between the teeth must be made relatively large to facilitate fast engagement. At the same time, the teeth must have an adequate extension to withstand the load. Normally, this means that the extension of a tooth represents approx. 20-30 % of the"intermediate spacing". To increase the speed further when moving into engagement, the teeth according to the invention are provided with a relatively long sloping rear part 34A', i. e. on the part located on the opposite side in relation to the meshing surface 34C'. Thanks to this execution, and its correspondence at interacting recesses, a very small flat part 34B'is obtained, i. e. small exposed axial limiting surface, so that the probability of swift engagement increases dramatically on fast axial movement of the driver, yet good strength is retained at the same time. The inclined surfaces 32A, 32A'can also be executed straight, since these always leave one another when driving forwards. However, at least one of the surfaces 34A, 34A'must be sharply inclined to force the driver 32 out of engagement with the gear wheel in case the spring 62 should not succeed in having done this.

Figures 7,8 and 9 show views corresponding to the above, but for a driver 22 according to a preferred execution according to the invention. A front view is shown (a rear view) (Figure 9) with projecting male element 32, which is provided with an inclined part

32A, a flat part 32B and a right-angled meshing surface 32C (Fig. 8). It is also shown that the driver 22 on its inner limiting surface is provided with teeth 21 intended to interact with teeth formed in a corresponding manner on the output shaft 20, so that axial displacement can take place at the same time as the driver 22 is fixed in a radial direction on the shaft 20. Figure 7 shows a view from the opposite side, where the driver 22 is provided with recesses 34. These recesses consist of a sharply inclined, bevelled surface 34A and a flat surface 34B and finally an acute-angled meshing surface 34C (which can also be made straight). The acute-angled meshing surface 34C is clearest from Figure 8, which also clearly shows the track 25 in the outer periphery of the driver.

Figures and 13 show important modifications according to a preferred execution according to the invention. Since the basic principles according to the preferred modification are the same as described earlier, the description below will focus mostly on important differences. It is evident from Figure 10 and Figure 11 that the basic execution of the gear control device is the same, with a gear drum 58, disposed on which is a multiplicity of tracks 56, for control of shift forks 36 via control pins 46.

In contrast to the execution shown and described above, each shift fork 36 is provided with two control pins 46A, 46B, which interact and are controlled inside respective tracks 56 in the gear drum 58. One of the two control pins 46A is permanently anchored/fixed in relation to the shift fork 36. The other control pin 46B can however be moved a certain distance At in a lateral direction in relation to the shift fork 36. In addition, it is evident from Figures 10 and 11 that each shift fork 36 is provided with a control peg 70. This control peg 70 is fixedly anchored at the movable pin 46B, i. e. close to the gear drum 58 and has an extension which is parallel to the extension of the gear drum. The control peg 70 disposed by the movable pin 46B is disposed with its moving end 70A inside a corresponding recess 36A in the fixed part of the shift fork 36, so that the movable pin 46B is controlled by means of the control peg 70 to only move in a transverse direction. The recess in the shift fork 36 for the control peg 70 therefore also extends in a direction which is parallel to the extension of the gear drum. To obtain very good control and avoid any possible drawbacks (for example, a jamming effect, or hard edge loading), the control peg has been made such a length that in principle it entirely fills the recess as a whole when the movable control pin is in its most distant

position in relation to the shift fork 36. Thus this control pin 70 projects in a lateral direction from the shift fork 36 on one side of it when the movable pin 46B is in its inner position, i. e. lies close to the side of the shift fork 36, as shown in Figure 11. To be able to make a compact box, in which the shift forks can be moved to come close to one another, each shift fork 36 is provided on its other side with a recess 71, which is intended to be able to receive the projecting part 70A of the adjacent control peg, so that two control forks which lie next to one another, for example 36, 38, can be displaced to be in contact with one another. According to the preferred execution, the maximum thickness ts of each shift fork 36 is equal to, or essentially equal to, the combined thickness of a cog wheel td and a driver tm.

Figure 12 shows a preferred embodiment of an output shaft 20 with six cog wheels 1-6 for forward gears and a cog wheel R for the reverse function. It is also shown that six drivers 22,24,26,28,30,31 are arranged on this shaft 20. As already stated above, the basic principles are the same as described above. Thus only certain changes will be focused on. One change is that the recesses 32'in the gear wheels/cog wheels 1 on the deceleration side are not provided with any inclined/bevelled part. One end surface 32C'in this recess is intended to interact with the deceleration dog 32 (its surface 32C) on deceleration, while the other end surface 32A'of the recess 32'on the whole never comes into contact with the corresponding surface of the deceleration dog 32 of the driver, e. g. 24. This is achieved by arranging the meshing surfaces on cog wheel 1 or the driver respectively in a manner specially suited to the purpose. The figure shows a position in which the meshing surfaces 34C'of the acceleration dogs on cog wheel 1 are disposed at the same level 76 as the meshing surface 32C of the deceleration dogs 32 on the drivers. In this position, it is the case that the distance 11 between the meshing surfaces 34C'and 34C, which are in contact on acceleration, is less than the distance 12 between the opposing, non-contacting surfaces 32A and 32A'on the deceleration side.

As is evident from Figure 12, the difference is extremely small, often only approx. 1 mm but sufficient for no contact to occur.

It is evident from Figure 13 that the control tracks 49-56 in the drum (gear) 58 according to the preferred embodiment have a different form compared with Figure 1.

The primary difference in relation to Figure 1 is that five of the six tracks in the drum 58 are provided with a varying width tl, t2, along their extension. Only the control track for sixth gear is provided with a constant width t3, which corresponds to the width/diameter of a control pin 46. The other control tracks are formed along the greater part of their extension with a width tl, which corresponds to the outer dimension between the outer surfaces of two control pins 46A, 46B in a compressed position, when the movable pin 46B is pressed in towards the fixed pin 46A, in one and the same shift fork 36. In addition, it is shown that each of the five control tracks is provided with a part A-B where the width t2 is considerably greater than the remaining width tl.

Furthermore, adjacent on both sides to the wider part A-B is a part 1-A, in which the width increases from tl to t2, and on the other side a third part B-C, where the width decreases from t2 to tl. In the expanding part 1-A, the increase from tl to t2 takes place due to the fact that the left-hand side is angled out, so that the track is widened, while the right-hand side runs straight. In the third part B-C, the reduction takes place in the reverse manner, due to the fact that the left-hand side is kept straight and the right-hand side is angled in. The first angle al is shown to be considerably greater, roughly twice as great, as the other angle a2, which can be seen as an extra refinement which is not always entirely necessary, since thanks to the spring force 62, the shift fork should normally be held in the correct position even if the track were full-width t2.

It will be explained below how a gearbox according to the preferred embodiment functions when changing up or down respectively from first to second gear. In principle, this takes place as already described in connection with Figure 1. In the starting position, we are located by that marked as gear 1 in Figure 13. The left-hand shift fork 36 will have hereby guided the left-hand driver 22 into engagement with the cog wheel 1 on its left-hand side and the right-hand shift fork 38 will then have guided the right- hand driver 24 into engagement with cog wheel 1 on its right-hand side. In forward operation, the acceleration cogs 34'on cog wheel 1 will lie close to the flanks 34C inside the left-hand driver 22, so that a torque is transmitted to the output shaft 20. In connection with deceleration, the driver 24 will instead transmit an opposing torque on the opposing side, in the other direction, due to the fact that the decelerating dogs 32 interact with their one side 32C with the upper flank 32C'in the recess 32'in the first

gear cog wheel. The vehicle will thus be braked by the engine transmitting a decelerating torque via the gearbox. As is evident from the figures, the positions with regard to the meshing surfaces are such that the acceleration dog 34'is not pressed out of the inclined surface 34A in driver 22, but has room therein without exerting any axial or radial force. In the same way, there is no interaction between the lower surface of the deceleration dog 32 of the right-hand driver 24 and the non-active surface 32A'on the deceleration side of cog wheel 1 when accelerating.

When changing up is to take place from first to second gear, the gear shift bar is moved, at which the drum 58 rotates. In a first phase of this rotation, movement of the control pins 46A, 46B mkes place from the position in which the first gear is active to that marked by A, a widening of the left-hand track (for driver 22) from t 1 to t2 taking place at the same time as the right-hand driver continues to be entirely positively controlled in a width corresponding to t 1, the right-hand driver being moved a certain distance to the right in the picture. In this position, the right-hand driver 24 has not yet been moved sufficiently far in a transverse direction to engage with the acceleration dogs 34'of second gear. If the gear shift up is performed during acceleration (which is normal), the left-hand driver 22 will continue to be engaged in the acceleration dogs 34'on the first gear cog wheel, since the spring force 62 is not sufficiently great (when the torque is transmitted) to move the driver 22 with the shift fork 36 to the left in the picture.

However, the movement of control pins 46A, 46B to position A means that the shift fork 36 has the opportunity to be able to be moved to the left, if a retaining friction force between cog wheel and driver is to cease. During the next phase of changing up, the acceleration dogs 34'of the second gear cog wheel will enter the recess 34 in the driver 24. As soon as the dogs have engaged with the force-transmitting surface 34C of the driver 24, the rotational speed of the output shaft 20 will increase, i. e. correspond to the gear change between input and output cog wheel for second gear. At the same time as this, driver 22, which was previously engaged on the acceleration side of first gear's cog wheel, will increase its rotational speed, since it is connected in a rotationally fixed manner to output shaft 20, while the cog wheel of first gear on the output shaft will rotate at a lower speed. A consequence of this is that the inclined flank 34A of the driver 22 comes into contact with the inclined flank 34A'on the first gear cog wheel, the

driver being jogged to the left in the picture to be able to be released. Thus the consequence of this is that the shift fork 36 is also jogged to the left in the picture (due to the fact that the track 25 in the driver 22 guides it to the left), which can also happen since the track in this position (zone B) is of sufficient width t2 to facilitate a lateral movement. The force from the spring 62 also contributes to this lateral movement, since the retaining force ceases. The movable control pin 46B will not move in a lateral direction during this movement of the shift fork, but thanks to the spring 62 will remain in contact with the edge of the control track. When the gear shift bar is guided through the whole of zone B, second gear is fully engaged. At the same time as the movement of driver 24 in towards second gear's cog wheel from the left, a movement takes place in zone B of a third driver 26 from the right in the picture to engage on the deceleration side. (This is in principle the same type of movement as was made when the two drivers 22,24 were moved to engage with the cog wheel of first gear.) In the position for second gear also, the control track 56 of the first driver 22 will have the greatest width t2. However, all the other tracks have the"standard width"tl in this position. The width of the first track 56 is then reduced successively in the next zone 2-A, when the gear shift bar is moved from second gear to third gear. This is something which is consistently the same for all control tracks, but displaced to be adapted to the respective gear position.

When changing down from second gear to first gear, during a first stage (presumed to be deceleration) in zone B the deceleration dogs 32 will engage with their meshing edges 32C against the meshing surfaces 32C'in the cog wheel of second gear. The acceleration dogs 34'on the cog wheel of second gear will be located inside the recesses 34 in the left-hand driver 24, but without being actively engaged in any surface.

Immediately after the deceleration dogs in the third (from the right) driver 26 release their grip, the deceleration surfaces 32 of the driver 24, which are located to the left of the last-named, will engage in the cog wheel of first gear. This can be done since the cog wheel of first gear rotates more slowly than driver 24, and thanks to the fact that recess 32'is considerably longer than the extension of dog 32. Thus deceleration commences in this stage via the cog wheel of first gear. During the next phase of movement, between A and 1, the left-hand driver 22 will be guided into engagement

with the left-hand side of the cog wheel of first gear, due to the fact that the fixed control pin 46A is guided towards the left-hand wall in control track 56, when the width is also reduced from t2 to tl. The movable control pin 46B will be in contact with the right-hand wall for the entire time, preventing the driver from being able to move freely in towards the cog wheel, for example owing to the G-force.

Other gear changes up and down take place according to the same principles. The exception is the sixth gear, which is only provided with dogs on one side (thus no recesses on its other side), these dogs interacting with a sole driver 31, which driver is provided with recesses 47 for both acceleration and deceleration on the side which is directed ds the cog wheel of sixth gear. The track 48, in drum 58, is thus formed entirely in accordance with what has been described in Figure 1. According to this modification of the invention, a driver can thus be eliminated (compared with Figure 1).

Since from the highest gear there is no reason, as in the case of other gears, to be able to change up continuously swiftly, there is no need in this case to provide acceleration dogs and deceleration dogs respectively on each side of the gear wheel, at least not necessarily. Instead, only one side of the gear wheel in the highest gear can thus be provided with both deceleration and acceleration dogs respectively, in a known manner.

Dogs are then used which are provided with both deceleration surfaces and acceleration surfaces, which are certainly previously known in themselves.

On changing down and opening the throttle, the cutting out the engine is conceivable to be able to carry this out better.

The invention is not restricted to that demonstrated above, but can be varied in the scope of the following claims. Thus it is understood that the shaft design can produce many different representations. Furthermore, it is understood that the bearing positioning is also something which can be varied in a manner obvious to the expert. It is understood, for example, that instead of a drum, the shift fork control device can consist of a flat element with tracks for the control pin. Other types of arrangement are also possible as a shift fork control device, for example separate hydraulic units for each individual shift fork, which are controlled for example by means of electronics. Normally, a gearbox

according to the invention is used sequentially, but it is understood that the shift forks can be influenced, for example, by means of electronic control, so that the gear changes can take place non-sequentially, for example, directly from first gear to third gear without the gear wheel of second gear. In addition, electronically controlled synchronization can be used as a complement to the invention with the aim, for example, of being able to perform gear changes more quickly and even more distinctly.

Furthermore, an electronic unit of this kind can also be used to achieve certain engine disconnection, for example in combination with sensors which measure the lateral force to eliminate the risk of too great a torque transmission when changing gear on a bend, and/or to be able to achieve swift changing down while opening the throttle at the same time.

Furthermore, it is understood that the spring element 60, which forms part of the mechanism which interacts with the shift fork control device, can be formed in many different ways. On the one hand, leaf springs or the like can be used instead of spiral springs. Also, pins or the like which are influenced pneumatically can be used, it also being conceivable that such pins or the like can be locked/positioned in different positions and thereby be alternatively non-spring-mounted or spring-mounted.

Modifications comprising a resilient property in the actual shift fork are also possible.

Furthermore, it is conceivable that minimal, electronically controlled units can be used forming part of the mechanism, which provide spring cushioning or no spring cushioning alternately.

In addition, it is understood that the tracks shown, which control the control pins, can be varied to be arranged with other inclinations, with the principal function retained. As already described above, sloping of the meshing surfaces of the teeth/dogs can also be varied. It is understood that the inclination can be varied within wide bounds, but preferably within 0°-10°, with the function according to the invention otherwise retained. Furthermore, it is understood that the interacting surfaces can be arranged freely in the case of the dog or recess in the driver or cog wheel respectively.