GB1568067A

GB1568067A - Transmission device

Info

Publication number: GB1568067A
Application number: GB41725/76A
Authority: GB
Original assignee: VIRLON J
Current assignee: VIRLON J
Priority date: 1975-10-07
Filing date: 1976-10-07
Publication date: 1980-05-21
Also published as: SE7611024L; AU1847276A; NL7611048A; DE2645320A1; JPS5263554A; ES452381A0; AU515735B2; IT1068403B; ES452381A1

Description

(54) TRANSMISSION DEVICE (71) 1, JEAN-CLAUDE VIRLON, a French Citizen, of 15 rue de la Croix Blance, 77400 Collegien, France, do hereby declare this invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed to be particularly described in and by the following statement:- The invention generally relates to improvements made in mechanical transmission-gear devices, particularly for motor-cars.

The invention relates more particularly to improvements in an automatic transmission for mechanical gear change in which the changing mechanism consists of an entry shaft carrying two circular plates rotating jointly with this shaft, said plates being spaced from each other, and with at least one pair of rollers placed in this space and being able to be displaced radially between these plates, one pair of rollers being held in rolling contact with the facing surfaces of the plates, with a control member acting at least on the radial position of the pair of rollers, one pair of rollers being mounted to swing on a horizontally displaceable guide axle such that the abovementioned rollers can take up an inclined position on their guide axle, at least during the control period of radial position change due to which a self-displacement of the rollers is obtained either towards the greatest reduction ratio or towards the smallest reduction ratio; and one pair of rollers being mounted to swing on its guide shaft around the vertical passing through the contact points between rollers and plates.

The invention, in a transmission of the type described above, aims mainly to supply the appropriate means to increase the control sensitivity of the radial roller displacement of the changing mechanism by reducing the effort required to start their self-displacement and also to create the control means for the self-displacement of the said rollers, of the type to ensure a continuous change which is quite automatic and which is a function of the velocity of the exit (utilisation) shaft of the changing mechanism, on the one hand, and a function of the resisting torque.

To this effect the invention concerns a transmission-gear change device, particularly for motor-cars, comprising a mechanical gear change having an entry shaft and an exit shaft of which one carries two plates joined in rotation and spaced apart, at least one pair of rollers, carried by a fork and placed in the said space, and which can be displaced radially between these plates along guide shafts with which they rotate jointly, said pair of rollers being held in point rolling contact against the plates by means which applies a force tending to reduce the space between the plates, a control means comprising at least one torque regulator disposed on the entry and/or exit shaft arranged to act on said fork to change the radial position of the said pair of rollers, each of said pair of rollers being mounted to swing on its guide shaft around the axis passing through the contact points between rollers and plates, the connection between the rollers and the guide shafts being provided by drive parts arranged to be displaced axially along the said shafts, to integrate the roller rotation with that of the shafts, and, to permit free inclination of the rollers about the axis passing through the control points between rollers and plates.

According to one arrangement of the invention one pair of rollers is held in point rolling contact against each other and in point rolling contact against the plates.

According to another arrangement of the invention the same pair of rollers is held on an inclination control fork by means of a ball bearing, each pair of rollers receiving its movement from a pair of angularly displaceable discs arranged between the plates of the variable transmission, each disc being provided with an aperture for each roller to allow contact between an adjacent roller and plate and at least one spiralshaped radial groove in which the end of a pin carried by the said fork is engaged.

According to a characteristic of the invention the entry shaft or the exit shaft of the variable transmission is equipped with a torque regulator acting on the transmission ratio when the torque exceeds an assigned threshold, this torque regulator preferably being constituted of an elastic coupling formed by two cams each with an annular cam race of sinusoidal shape, opposed to each other and being in contact with each other through rollers or balls, a first cam being able'two move around one of the entry or exit transmission shafts, with an increase in resisting torque, and to cause the axial displacement of a second cam rotating together with one of the said shafts, this said axial displacement being suitable to cause a change in the transmission ratio between the entry shaft and the exit shaft of the variable transmission.

The inclination and consequently the radial position of the rollers may be controlled by means constituted, on the one hand, by a centrifugal regulator disposed on the exit (utilisation) shaft of the variable transmission and arranged to change the radial roller position as a function of the rotational velocity of the said exit shaft, and by a torque regulator, disposed on the entry shaft of the variable transmission and arranged to change the radial roller position when the resisting torque exceeds an assigned threshold.

According to one embodiment the swinging connection between rollers and guide shafts is achieved by placing balls into grooves of two parts, of spherical transverse profile, one part of each groove being produced within the radial thickness of one roller, the other part being produced in the space separating the axial channels provided on the guide shaft generatrices.

According to another embodiment the swinging connection between rollers and guide shafts is achieved by drive parts having, on the one hand, a first, spherical contact surface placed in a groove of spherical profile in the internal roller bore and, on the other hand, a second, plane contact surface opposite the first, spherical contact surface, supported on a plane guidance area on the roller guide shaft.

According to another embodiment the swinging connection between rollers and guide shafts is a type of cardan, this connection being achieved by a drive part in the form of a ring which is arranged coaxially in an internal roller boring, this ring being symmetrically thinned from each side of its mean plane of rotation, this ring being able to swing, on the one hand, around two axles diametrically opposed on a ring which can slide on the roller support shaft, and on the other hand being able to swing around two second diametrically opposed axles, fixed at 90" to the first axles, the second axles being integral to the roller, owing to which a universal joint is achieved which is particularly rationalized for the torque transmission between plates, rollers and roller support shafts.

Finally, according to another arrangement, the swinging connection between rollers and shafts is achieved by drive parts made of elastic materials like, for instance, elastomers.

Other arrangements, characteristics and advantages will become apparent from the detailed descrition of the arrangements according to the invention, illustrated by way of examples in the attached drawings in which Figure 1 shows a partially schematic longitudinal section of a first embodiment, Figure 2 shows a transverse section following 11-Il of Figure 1.

Figure 3 is a section according to III--III of Figure 4 showing the detail of the swinging roller mounting of the variable transmission, Figure 4 shows the top of the rollers with detail of the inclination control, Figure 5 shows a partially schematic longitudinal section of a second embodiment of the invention Figure 6 shows a section according to III--III of Figure 7, Figure 7 shows a top view of the rollers with the detail of the inclination control, Figure 8 shows a section according to III--III of Figure 9, Figure 9 shows a top view of Figure 8, Figure 10 shows a section according to 111-111 of Figure 11 Figure 11 shows a top view of Figure 10, Figure 12 shows a section according to III--III of Figure 13, Figure 13 shows a top view of Figure 12, and Figure 14 shows a partial section of an elastic coupling between rollers and guide shafts.

According to a first embodiment, represented in Figures I to 4, the variable transmission is designated by general reference 1. The variable transmission comprises a case 2 inside of which the various components are arranged. The case is closed at one of its ends by a removable cover 3 which gives access to the mobile parts of the variable transmission.

The mobile parts of the variable transmission comprise an entry shaft 4 and an exit (utilisation) shaft 14.

Within the framework of an automatic motor-car transmission the entry shaft is linked to the vehicle motor shaft by means of a centrifugal clutch or an hydraulic coupling known per se.

The exit shaft 14 will be able to drive a differential shaft directly. In this type of transmission it will be noted that up to now the control of the variable transmission is not subject to a device which responds to the depression existing, for instance, in the gas intake pipe of the vehicle engine.

The entry shaft 4 of the variable transmission, centred in the case 2, is provided with two circular plates 5, 6 which rotate together with the entry shaft 4.

Plate 5 is nevertheless axially mobile so that it can transmit the force applied by a spring 19 whose function will be described in detail later. Between the plates 5, 6 a space 7 is provided to place at least one pair of rollers 8, 9, respectively.

One pair of rollers is held in point rolling contact against each other and in point rolling contact on the surfaces of the opposite plates 5, 6.

The rotation of rollers 8, 9 is integral with that of shafts 8a, 9a, respectively; these guide shafts are parallel to the plane of rotation of plates 5, 6 and extend radially between entry shaft 4 and the periphery of case 2 which they cross through centering holes.

The rollers 8 and 9 can be displaced along the shafts 8a and 9a. The radial roller displacement between plates 5, 6 is obtained by means of a control fork 10 schematically represented in Figures 1 and 5 and shown in more detail in Figures 3 and 4.

The shafts 8a, 9a are linked in rotation by means of toothed wheels 11 and 12. The toothed wheel 12 meshes with a toothed crown 13 integral with the exit shaft 14.

In order to achieve the permanent adaptation of the rate of change as a function of the angular velocity of the exit shaft and as a function of the resisting torque with a great sensitivity and with next to no effort, the contact between each pair of rollers 8, 9 and the guide shafts 8a and 9a, is made by means of rolling elements due to which rollers 8, 9 are allowed to swing freely around a virtual axis marked 20. The swinging movement causes the rollers to take up an inclined position and consequently causes them to describe a spiral trajectory on the plates 5, 6 practically without slippage. As soon as the roller inclination is started in one direction or the other a radial self-displacement of the rollers occurs, either from the periphery of plates 5, 6 towards shaft 4, or vice versa.

In the embodiment of Figures 3 and 4 the rolling elements are the balls 21, for instance three, fixed at 1200. Between shafts 8a, 9a and the rollers 8, 9 the balls 21 are placed in grooves 22 which are in two parts of spherical transverse profile.

A part 23 of each groove is produced in the thickness of a roller 8 or 9 while the other part of each groove is produced by the space which separates the axial channels 24 of shafts 8a or 9a.

Also as shown in Figures 3 and 4, the rollers 8, 9 are held in the control fork 10 by means of ball bearings 25. In the embodiment of Figures 1 to 4 the inclination control fork 10 for the rollers around the virtual axis 20 receives its movement from a pair of angularly displaceable discs 26 arranged between plates 5, 6 of the variable transmission and centred between radial guides 27 of case 2. The discs have apertures through them as can be seen, for example, from Figure 4 to allow the necessary contact between plates and rollers and to allow radial movement of the rollers. These apertures are hidden in Figure 2 and in the plane of Figure 1.

Each disc 26 is provided with at least one radial groove 28, three in the example shown in Figure 2, of which only one is shown in Figure 1 where the discs are cut back so as to illustrate schematically the connection between the fork 10 and a groove 28. Each groove is spiral shaped and acts as a guide to a pin 30 of fork 10. The discs 26 rotate together by means of connecting pins 29. Due to the very weak displacement inertia of the rollers between the plates 5, 6 it is possible to ensure direct transmission control by a torque regulator and a centrifugal regulator, these two devices acting, or acting together on the radial position of the rollers and consequently on the transmission ratio of the variable transmission.

The torque regulator is common to the embodiments of Figures 1 and 5. The torque regulator which is arranged on the entry shaft 4 of the variable transmission is constituted by an elastic coupling generally marked 35. The coupling is formed by two cams 36, 37 with cam races 38a, 38b of sinusoidal shape, facing each other and making contact through the interposition of balls 39. The first cam 36 is rotated by entry shaft part 4a. With an increase in the resisting transmission torque this first cam can move around the plate-carrying shaft 4.

Through the play of the cam races this rotation of the first cam causes cam 37 to move back towards plate 5. The movement is used, on the one hand, to increase the pressure action of spring 19 and, on the other hand, to act on the radial roller position.

In the embodiment of Figure 1 the axial movement of cam 37 is transmitted by a circular support projection 37a supporting a fork 40 connected to a lever 41 pivoting around fixed point 42. The lever 41 has an end 42a connected to an end 43a of the body of an hydraulic jack 43. This jack has a control rod 43b connected to a lever 44 which pivots around a fixed point 45 and drives pin 47 of a control shaft 48 by means of a fork 46. The shaft 48 carries a fork 49 which supports the connecting pin 29 of discs 26. The hydraulic jack 43 also functions by means of an oil pump 50 which is rotated by the pinion 11 of the variable transmission. The oil is fed into the case 2 by a pipe 51 and is supplied by a pipe 52 to the entrance of an hydraulic centrifugal regulator 53 arranged on the exit shaft of the variable transmission.

The regulator 53 feeds through a pipe 54 into the hollow rod 43b of the jack such that it runs through the piston 43c and fills the volume of the chamber 43d, causing it to vary.

A spring 43 around the piston rod 43b ensures that the latter returns towards the bottom of the chamber 43d.

In the embodiment of Figure 5 the change in the radial roller position is obtained mechanically.

In this respect it will be noted that the torque regulator 35 communicates its movement by means of the cam 37 to a fork 40 which is provided with a connecting part 50 connected to a return lever 51 pivoting about a fixed point 52. The return lever drives a connecting part 53 connected to a control lever 54 which is driven by the torque regulator 35 or centifugal regulator 55. This regulator is comprised of weights 56 suitable to displace a ring 57 axially under the influence of centrifugal force.

The ring 57 transmits its axial displacement movement by a circular support projection 58 which carries a fork 59 connected to a lever 60 which pivots around a fixed point 61. The lever 60 has a branch 60a connected to the control lever 54 by a connecting piece 62.

The lever 54 has between its two ends a connecting pin 54a with a control rod 63 which itself is connected to the control fork 10 of rollers 8, 9.

The operation of the transmission is the same whatever embodiment is adopted.

To explain this operation it must be allowed that the entry shaft part 4a of the variable transmission is driven by an internal combustion engine with the interposition of a centrifugal clutch or an hydraulic coupling of known type. It must also be allowed that the exit shaft 14 of the variable transmission is connected by a differential or other transmission to the driving wheels of a vehicle.

In an operationa phase without, or with very little, resisting torque the torque regulator 35 does not act on the radial position of rollers 8, 9. In the same operational phase the centrifugal regulator 53 or 58 changes the position of rollers 8, 9 as a function of the rotational velocity of shaft 14. With a rise in this velocity the rollers 8, 9 are radially displaced such that they tend towards the smallest transmission ratio, that is about 1 to 1 between entry and exit shafts of the variable transmission. With a decrease in the shaft 14 velocity the centrifugal regulator 53, 55 tends to displace the rollers 8, 9 towards the greatest transmission ratio (reduction), thus releasing the increasing engine regulation.

When the resisting torque stabilizes or drops the torque regulator tends to displace the rollers 8, 9 towards the smallest transmission ratio, around 1 to 1.

In the case of a sudden or slow interruption in the driving conditions, when, for instance, the accelerator pedal is no longer depressed, the action of the torque regulator becomes reversible, acting then to displace the rollers 8, 9 towards the greatest transmission ratio, producing an engine braking effect on the vehicle by increasing engine regulation.

Three main operating modes can, therefore, occur: accelerator pedal in central position, resisting torque practically zero (economical maintenance of the vehicle speed on the flat), the radial roller position is stabilised by the centrifugal regulator 53, 55, accelerator pedal fully open, engine torque rises abruptly, torque regulator 35 action tends to displace the rollers 8 and 9 towards the greatest reduction ratio.

Finally, it will be noted that the torque regulator, by the play of axial displacement of cam 37 acts on the spring 19 tension compressing plates 5, 6 permitting the control pressure between plates and rollers to vary as a function of the torque force to be transmitted. Thanks to the double device of transmission regulation and the swinging mounting of the rollers of the variable transmission a continuous adaptation of the transmission ratio is obtained. Because of this the rollers are practically never stabilized on one and the same rolling path which is of particular interest with respect to the attitude of the contract pieces because the film of lubricant is never broken and wear is distributed over the whole contact zone between rollers and plates.

In conformance with any of the embodiments shown in Figures 6 to 14, one pair of rollers 8, 9 are applied only with point rolling contact against plates 5, 6 which are subjected to a pressure force tending to apply them against the rollers.

In these embodiments there thus exists a space 65 between the rollers which are not bearing against each other in rolling contact.

To permit torque transmission between plates, rollers and shafts different constructions have been envisaged for the drive means which in each case allow for the absence of roller to roller contact.

In the embodiment represented in Figures 6 and 7 the swinging connection between rollers 8, 9 and guide shafts 8a, 9a is produced by drive parts 66. These drive parts have a spherical contact surface 66a, placed in a groove 67 also of spherical profile arranged in the internal boring of the roller, on the one hand, and, on the other hand, opposite the said spherical surface, a second plane contact surface 66b resting on a plane guide area 68 arranged longitudinally on the roller guide shaft.

Due to this constructional solution the rollers can shift, on the one hand, along the longitudinal guide areas of shafts 8a, 9a and, on the other hand, these rollers can swing by means of their spherical contact surface when the fork 10 is brought into inclination.

In the embodiment shown in Figures 8 and 9 the swinging connection between rollers 8, 9 and guide shafts 8a, 9a is produced by the drive parts 69 which are wheel-shaped.

The rotational planes of these wheels include radii 69a of the roller guide shafts.

Wheels 69 are partly placed in longitudinal grooves of curved profile arranged in the internal boring of the rollers, and partly in longitudinal grooves 71 arranged on the roller-carrying shafts 8a, 9a. The wheels are carried by axles 72 which are perpendicular to the longitudinal grooves 70 of the internal roller boring.

Due to this arrangement a simultaneous rolling contact is obtained between the wheels 69 and the internal roller grooves, and these same wheels 69 with the grooves on the shafts 8a, 9a.

In the embodiment shown in Figures 10 and 11 the swinging connection between rollers and guide shafts is produced by the drive parts 73 which are wheel-shaped. The sheels 73 are carried by the axles 74 aligned on the radii 74a which pass through the centre of guide shafts 8a, 9a. The planes of rotation of wheels 73 are perpendicular to the wheel-carrying axles 74. The wheel axles 74 are radially fixed in their thickness to the rollers. The wheels 74 have on the guide shaft side a lateral contact face 74a in the shape of a truncated cone which can roll between the conical sides of a longitudinal groove 75 arranged along guide shafts 8a, 9a.

It will be noted that in each of the embodiments of Figures 6 to 11 there are three drive parts and the corresponding guide grooves.

In the embodiment of Figures 10 and 11 there is still rolling contact between the drive parts and the guide grooves of shafts 8a, 9a, particularly under the effect of the rotational torque of the rollers.

In the embodiment of Figures 12 and 13 the swinging connection between rollers 8, 9 and guide shafts 8a, 9a is of the cardan type.

This connection is produced by a drive part 73 which has the form of a ring coaxially arranged in the internal bore of a roller. The ring 73 is symmetrically thinned on either side of its mean plane of rotation such that the rollers can swing with respect to this ring and with respect to the shafts 8a, 9a. The ring 73 can swing on the one hand around two first diametrically opposed axles 74, arranged with an integral to a ring 75 sliding on channels 76 of shafts 8a, 9a.

On the other hand, the ring 73 can swing around two second axles 77, shown in Figure 8, these axles also being diametrically opposed and fixed at 900 to the two first axles 74. The said second axles 77 are integral with a band or cage 78 which itself is rotationally integral with rollers 8 or 9.

Due to this constructional solution a particularly pure universal joint is produced for the torque transmission between plates 5, 6, rollers 8, 9, and guide shafts 8a, 9a.

Finally, in the embodiment shown in Figure 14 in partial section, the connecting part between rollers and shafts is produced by a drive part 79 made of elastic material and joined on the one hand to a ring 75a of the type described for the embodiment of Figures 7 and 8, and, on the other hand, to the internal face of the roller bore.

This type of construction naturally allows a roller inclination movement around the axis line 20. This type of construction allows particularly the production of a nonlubricated variable transmission.

It will be noted that the radial displacement of the rollers is obtained by a very small angular inclination of these rollers whatever the embodiment adopted.

Moreover, in order to reduce the forces due to the radial displacement, ball sockets could be provided on their guide shafts for the radial sliding of the rollers.

To ensure the inclination movement of the rollers hydrostatic swivel joints could also be provided between rollers and guide shafts.

Naturally the invention is not limited to the embodiments described and shown above and other versions can be provided without leaving the framework of the

Claims

attached claims. WHAT I CLAIM IS:

1. A device for a gear-change transmission, particularly for motor-cars, comprising a mechanical gear-change with an entry shaft and an exit shaft, one of which carries two plates rotating together and spaced apart, at least one pair of rollers carried by a fork and placed in the said space and being able to be displaced radially between these plates along guide shafts rotationally integral with these rollers, said pair of rollers being held in point rolling contact with the plates by means which applies a force tending to reduce the space between the plates, a control means comprising at least one torque regulator disposed on the entry and/or exit shaft arranged to act on said fork to change the radial position of the said pair of rollers, each of said pair of rollers being mounted to swing on its guide shaft around the axis passing through the contact points between rollers and plates, the connection between the rollers and the guide shafts being provided by drive parts arranged to be displaced axially along the said shafts, to join the rollers and the shafts rotationally, and to allow the rollers free inclination around the axis passing through the contact points between rollers and plates.

2. A device according to Claim 1, characterized in that one pair of rollers is held in point rolling contact with each other and in point rolling contact with the plates.

3. A transmission device according to Claim 1, characterized in that one pair of rollers is held only in point rolling contact against the plates.

4. A transmission device according to any one of the preceding claims, characterized in that the rollers of the same pair are held on an inclination-control fork by means of a ball bearing, each pair of rollers receiving its movement from a pair of angularly displaceable discs arranged between the plates of the variable transmission, each disc being provided with an aperture for each roller to allow contact between an adjacent roller and plate and at least one radial spiral-shaped groove in which the end of a pin carried by the said fork is engaged.

5. A transmission device according to any one of the preceding claims, characterized in that the entry shaft or the exit shaft of the variable transmission is equipped with a torque regulator acting on the transmission ratio when the torque exceeds an assigned threshold, this torque regulator being constituted by an elastic coupling formed of two cams each with an annular cam race of sinusoidal shape, facing each other, and being in contact with each other by means of rollers or balls, one first cam being able to move around one of the entry or exit shafts of the transmission with an increase in the resisting torque, and to cause the axial displacement of a second cam rotating together with one of the said shafts, the said axial displacement being suitable to cause a change in the transmission ratio between the entry shaft and the exit shaft of the variable transmission.

6. A transmission device according to any one of the preceding claims, characterized in that the means of control for the inclination and, consequently, the radial roller position, are constituted by a centrifugal regulator disposed on the exit shaft of the variable transmission and arranged to change the radial roller position as a function of the rotational velocity of the said exit shaft, and by a torque regulator disposed on the entry shaft of the variable transmission and arranged to change the radial roller position when the resisting torque exceeds an assigned threshold.

7. A transmission device according to Claim 5 or Claim 5 and Claim 6, characterized in that the torque regulator is arranged on the entry shaft of the variable transmission, the said second cam being urged towards the first cam by a pressure spring providing said means which applies a force tending to reduce the space between the plates such that, as a function of the resisting torque the pressure between plates and rollers is changed on the one hand, and the radial position of the said rollers on the other hand, by means of a connection between the said second cam and the control fork of the said rollers.

8. A transmission device according to any one of Claims 4 to 7, characterized in that the control means acting on the radial roller position are constituted by a centrifugal hydraulic regulator arranged on the exit shaft of the variable transmission to feed an hydraulic jack, one end of which is connected by a mechanical connection suitable for the angular displacement of the discs controlling the displacement of a roller-carrying fork, the other end of the said hydraulic jack being connected to the axially mobile cam of the torque regulator.

9. A transmission device according to any one of Claims 1 to 3, characterized in that the roller position control fork is directly displaceable by a mechanical connection with an axial displacement cam of a torque regulator arranged on the entry shaft of the variable-transmission, on the one hand, and, on the other hand, equally directly by a mechanical connection connected to a mobile ring of a mechanical centrifugal regulator arranged on the exit shaft of the variable transmission.

10. A transmission device according to any one of the preceding claims, characterized in that the swinging connection between rollers and guide shafts is produced by drive parts in the shape of balls placed in channels which are in two parts, of transverse spherical profile, one part of each channel being produced in the radial thickness of one roller, the other part being produced by the space separating the axial channels arranged on the guide shaft generatrices.

II. A transmission device according to any one of Claims 1 to 9, characterized in that the swinging connection between rollers and guide shafts is produced by drive parts having a first, spherical contact surface placed in a channel of spherical profile provided in the internal bore of the roller, on the one hand, and, on the other hand, a second, plane contact surface, opposite the first, spherical contact surface supported on a plane guidance area provided on the roller guide shaft.

12. A transmission device according to any one of Claims 1 to 9 characterized in that the swinging connection between rollers and guide shafts is produced by drive parts which are wheel-shaped with rotational planes which pass through the radii of the roller guide shaft, these wheels being placed partly in the longitudinal channels provided in the internal boring of the rollers and partly in the longitudinal channels arranged on the roller-carrying shafts, these rollers being carried by axles which are perpendicular to the longitudinal channels of the internal roller boring.

13. A transmission device according to any one of Claims 1 to 9, characterized in that the swinging connection between rollers and guide shafts is produced by drive parts which are wheel-shaped and carried by axles aligned along radii passing through the centre of the guide shafts, the rotational planes of the said wheels being perpendicular to the wheel-carrying axles, the wheel axles being radially integral with the rollers in their thickness, the wheels having a lateral contact surface in the shape of a truncated cone on the side of the guide shafts and being able to roll between the flanks of a longitudinal channel of the same profile, arranged along the guide shafts.

14. A transmission device according to any one of Claims I to 9, characterized in that the swinging connection between rollers and guide shafts is of the cardan type, this connection being produced by a drive part in the shape of a ring coaxially arranged in the internal boring of a roller, this ring being thinned symmetrically on either side of its mean rotational plane, this ring being able to swing around two diametrically opposed first axles arranged on a ring which can slide on the roller-carrying shaft on the one hand, and, on the other hand, being able to swing around two second diametrically opposed axles fixed at 900 to the two first axles, the said second axles being integral with the roller.

15. A transmission device according to any one of Claims 1 to 9, characterized in that the swinging connection between rollers and guide shafts is produced by drive parts made of elastic material, for instance of the elastomer type.

16. A device for a gear-change transmission according to Claim 1 substantially as described hereinbefore with particular reference to any of the embodiments illustrated in the accompanying drawings.

17. A device for a gear-change transmission according to Claim 1 substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 5 of the accompanying drawings.