GB2303424A

GB2303424A - Torsion damper

Info

Publication number: GB2303424A
Application number: GB9614461A
Authority: GB
Inventors: Steffen Lehmann
Original assignee: LuK Lamellen und Kupplungsbau GmbH
Current assignee: LuK Lamellen und Kupplungsbau GmbH
Priority date: 1995-07-14
Filing date: 1996-07-10
Publication date: 1997-02-19
Anticipated expiration: 2016-07-10
Also published as: BR9603063A; FR2736698A1; FR2736698B1; GB2303424B; DE19626687B4; GB9614461D0; DE19626687A1

Description

TORSION VIBRATION DAMPER The present invention relates to torsion vibration dampers more particularly for use for motor vehicle clutch discs for friction clutches, in the drive train of vehicles.

Furthermore the invention relates in particular to torsion vibration dampers with a pre-damping device having at least one energy accumulator of lower stiffness, and a main damping device having at least one energy accumulator of higher stiffness, wherein the energy accumulators are operatively mounted between each input and output part of the predamping and main damping devices, the output part of the main damper being connected radially inside the main damper energy accumulator to the hub part with a torsional play existing over a certain area, and the predamping device being operationally connected on the output side with the hub part, for which the hub part and flange part each have gearing aligned towards each other and provided with circumferential play relative to each other, and in the radial area of the gearing recesses are provided in both the flange part and in the hub part so that a predamping energy accumulator is housed roughly half in each and at least one friction damping device is operationally mounted parallel to the predamping energy accumulators With torsion vibration dampers of this kind which are formed with a predamper and a main damper, the predamper can be mounted in an installation chamber axially between the main damper flange and one of the two side discs, as described for example in the case of the torsion vibration dampers of clutch discs according to DE-OS 39 18 167.

This design variation of a torsion vibration damper with a predamper and main damper requires extra installation space in the axial direction.

A further design possibility of a torsion vibration damper with a predamper and main damper can be achieved if the predamper energy accumulators are mounted radially in the gearing area between the inner gearing of the main damper flange and the outer gearing of the hub as well as axially in the area of the main damper flange.

The elastically resilient elements, such as energy accumulators of the predamper are housed in recesses opposite one another in the circumferential direction in the inner gearing of the main damper flange and outer gearing of the hub, as shown for example according to DE-PS 28 14 240, DE-OS 34 47 652 AND DE-OS 34 47 653. With these predampers of torsion vibration dampers shown in the above specifications the predamping energy accumulators, such as springs or elastic elements, are housed in cut-out sections provided for this purpose in the hub gearing and engage in the radial direction with holding means mounted on their end areas against stop contours provided for this purpose on the inner gearing of the hub flange and outer gearing of the hub.

A torsion vibration damper according to DE-PS 28 14 240 has in addition to the predamper also a predamping friction disc. This predamping friction disc is produced so that it is mounted radially outside of the outer diameter of the predamping energy accumulators and radially inside the inner diameter of the main damper energy accumulators and has in its radially inner area an inner gearing in the radial direction which equates with the inner gearing of the flange disc and engages in the outer gearing of the hub.

It is further known that with a force biasing of the friction linings between the flywheel and the pressure plate a displacement of the axis of rotation of the friction linings as well as of the entrainment and counter discs takes place in comparison with the axis of rotation of the hub and gear input shaft.

The object of the present invention is to provide a torsion vibration damper of the kind already mentioned which ensures a self-centring function and at the same time retains a predamper and a main damper with at least two friction damping systems as well as has a cost-reducing simple compact structure which allows cost-effective production through simplified assembly and lower number of parts.

According to the invention this is achieved with a torsion vibration damper of the kind mentioned at the beginning in that an axially conical intermediate element, such as plastics component, provided between hub part and input part of the torsion vibration damper, for whose conical surface the input or hub part of the torsion vibration damper has a similar counter face, engages through each two axially projecting shoulders in each of the recesses of the hub, and the predamping energy accumulator is provided between the shoulders.

For the construction and functioning of the torsion vibration damper it can be particularly advantageous if the conical intermediate element is mounted substantially radially in the area between the hub part and the inner gearing of the main damping flange.

It can be advantageous if the axial projections of the ringshaped intermediate element are each arranged in pairs and on the circumference of the intermediate element there is at least one pair, preferably two pairs of radial projections which engage axially in radial hub gearing. If more than one pair of axial projections are located on the circumference of the intermediate element then a regular arrangement of the pairs of projections can be expedient.

Furthermore it can be advantageous if the free angles between each two pairs of axial projections on the circular ring shaped intermediate element arranged in pairs along the circumference of the circular ring shaped intermediate element are not the same size and viewed circumferentially are arranged irregular.

It can be particularly advantageous if between the axial projections of the intermediate element which include the predamping energy accumulators between them and the contact bearing areas of the hub part provided for same there is no rotational play and the outer faces of the axial projections pointing in the circumferential direction come to rest against the end contours of the recesses in the hub gearing.

A further development of the invention proposes that torsional play exists between the projections of the intermediate element in the axial direction and the contact bearing areas of the hub part provided therefor in the circumferential direction.

With a design of the clutch disc according to the invention the intermediate element has holding means on its projections arranged in pairs and pointing in the axial direction each on the side faces directed towards each other in pairs in the circumferential direction, these holding means projecting at least partially into the energy accumulators and being provided in the recesses to secure the contact of the energy accumulators.

It can be expedient that each energy accumulator of the predamping device in the radial direction only in a first radially inner partial area of its radial diameter enters into the areas provided on the intermediate element between the axial projections and in a second radially outer radial partial area of its radial diameter of each relevant energy accumulator enters in a recess in the output part of the main damping flange, which recess is expanded in the axial and radial directions.

When fitting the predamping energy accumulators in the recesses provided for same it can be expedient if the predamping energy accumulators are inserted with slight pretension in the recesses provided for same.

A further advantageous design of the invention is characterised in that on the side of the flange in the axial direction which is opposite the side in the axial direction on which the conical friction surface of the intermediate element is mounted and between the flange and the side disc, such as entrainment disc or side disc, located on this side of the flange, there are at least two axially resiliently tensioned energy accumulators, such as plate spring like elements which can cover one another at least partially in the axial direction and/or in the radial direction so that one energy accumulator with the larger outer diameter causes a resilient tensioning between the main damper flange and the side disc connected rotationally secured to the input part of the torsion vibration damper, as well as the second energy accumulator with the smaller outer diameter causes a resilient tensioning between a circular ring shaped disc adjoining the hub in the axial direction and a side disc connected rotationally secured to the input part of the torsion vibration damper and the one circular ring shaped energy accumulator, such as plate spring, with the larger outer diameter in its radially outer area biases the output part of the main accumulator, the flange, resiliently in the axial direction and in this contact area or at this contact face between plate spring and flange a friction damping can be produced as a result of the contact pressure exerted by the resilient tensioning.

Furthermore it can be expedient if the circular ring shaped energy accumulators resiliently tensioned in the axial direction, such as plate spring elements, are each constructed with a circular ring shaped foundation body and these circular ring shaped foundation bodies are provided in the radial direction with holding means which can be aligned in the radial direction to the axes of rotation of the plate springs and/or in the radial direction away from the axis of rotation and can engage on holding means provided for this such as recesses or moulded areas in the side disc for security against rotation.

Furthermore the torsion vibration damper can preferably be designed so that the torsional play between the profile of the hub external gearing and the profile of the inner gearing of the output part of the main damper is asymmetrical, ie the ratio between the torsional play in the pull direction to the torsional play in the push direction is greater or smaller than 1. In another possible use it can be expedient if the torsional play between the profile of the hub external gearing and the profile of the inner gearing of the output part of the main damper is symmetrical, ie the ratio between the torsional play in the pull direction to the torsional play in the push direction is equal to 1.

The material of the conical circular ring shaped intermediate element and/or of the circular ring shaped friction disc can be selected so that the conical circular ring shaped intermediate element and/or the circular ring shaped friction disc is made of sliding or friction material and/or is coated with such material.

An embodiment of the invention will now be explained with reference to Figures 1 to 4 in which Figure 1 is a sectional view of a clutch disc; Figure 2 shows a partial area of the clutch disc according to the section of Figure 1, on an enlarged scale; Figure 3 is a view of the gear box side of the clutch disc (in the direction I in Figure 1) and Figure 4 is a cut-out section of the clutch disc according to Figure 3, but without counter disc.

The clutch disc 1 shown in Figures 1 to 4 contains a predamping device 2 and a main damping device 3. The input of the clutch disc 1 which represents at the same time the input part of the main damper 3, is formed by an entrainment disc 5 which supports friction linings 4, and the counter disc 7 which is connected rotationally secured through spacer bolts 6. The output part of the main damper 3 is formed by a disc part, such as the main damper flange 8, which is mounted concentric with the ntrainment disc 5 and the counter disc 7 and which has a radially inner gearing 8a which engages in the radially outer gearing lia of a hub part 11 which forms the output part of the clutch disc.

The inner gearing 8a of the flange 8 and the outer gearing ila of the hub part 11 are designed so that in the circumferential direction a toothed flank play 21a,21b is produced which corresponds to the active angular area of the predamper 2.

The hub part has as output part of the clutch disc an inner gearing 12 which holds a gear input shaft. The main damper 3 has energy accumulators 13 which are provided in window like recesses 14,1 5 of the entrainment disc 5,7 on one side and in window-like recesses 16a,16b of the flange 8 on the other side. Between the discs 5 and 7 connected rotationally secured together and the flange 8 relative rotation is possible in the circumferential direction against the action of the energy accumulators 13 of the main damper. This relative rotation is restricted when the spacer bolts 6 which connect the entrainment disc 5 and counter disc 7 together stop against the end contours 17a of the cut-out sect ions 17 of the flange 8 through which they axially project.The window-like cut-out sections 16a,16b of the flange 8 in which the main damper springs 13 are housed can have as shown in Figure 4 on one side an extension in the circumferential direction, such as 16b, which corresponds approximately to the extension of the springs 13 in the circumferential direction, and on the other side an extension in the circumferential direction, such as 16a, which is greater than the extension of the springs 13 in the circumferential direction.With the illustrated embodiment with each two diametrically opposite window-shaped recesses of the flange 8, wherein the opposing recesses each have the same extension in the circumferential direction, but the two pairs of recesses having different extension however in the circumferential direction and with the non-symmetrical positioning shown in Figure 4 of the springs 13 in the window shaped recesses 16a of the flange 8 with enlarged extension in the circumferential direction, a differentiated torque characteristic of the main damper can be produced as a function of the turning angle between the flange 8 and entrainment and counter disc 5,7 on one side in the push direction and in the pull direction on the other side.

The present embodiment shows with a turning of the entrainment and counter disc opposite the flange disc in the pull direction a spring action as a result of the engagement of all four main damper springs on each relevant stop of the window shaped recesses wherein with turning of the entrainment and counter disc opposite the flange disc in the push direction there is only a spring action as a result of engagement of two or four springs on the relevant stops of the window shaped recesses.

The hub 12 can be used as a sintered hub or as a punched hub.

The predamper 2 is mounted axially in the area of the outer gearing of the hub 11 and the inner gearing of the flange 8 as well as radially in the area between the hub part 11 and the flange 8. The inner gearing of the output part of the main damper 3 of the flange 8 forms at the same time the input part of the predamper 2. The flange 8 has radially in the area of the inner gearing 8a recesses 8b whose defining faces 8c in the circumferential direction serve as bearing faces for the predamper energy accumulators 18. The recesses 8b of the flange 8 only receive the predamper energy accumulators 18 in an area of their extension in the radial direction. The hub part 11 has in the area of the outer gearing lla recesses lib which in the radial direction lie substantially opposite the recesses 8b of the flange 8.

In the circumferential direction the extension of the recesses llb of the hub part 11 expands in comparison with the extension of the recess 8b in the circumferential direction in the flange part 8.

With the illustrated embodiment the expansion of the recess 11b in comparison with 8b is formed so that the recess ila is widened symmetrically on its edge areas.

The output part of the predamper 2 is formed by an intermediate part connected rotationally secured to the hub 11 and which can be made for example cost-effectively as a plastics component and can be fibre reinforced in advantageous manner.

The intermediate element 9 is ring-shaped and is mounted axially between the hub 11 and flange part 8 and the entrainment disc 5. The ring-shaped intermediate element 9 has axially in the direction of the hub, shoulders 9a which engage in the recesses of the hub gearing in the axial direction. The shoulders are mounted in pairs in the embodiment illustrated in Figure 3 so that the relative faces 9b lying outside in the circumferential direction of each pair of shoulders 9a of the intermediate element 9 come to adjoin the corresponding inner edges lic of the recesses 11b of the outer gearing lla of the hub 11.The shoulders 9a and the distance between the shoulders each arranged in pairs are dimensioned so that the spacing between the circumferentially inner faces 9c of the shoulders is substantially equal to the spacing of the recesses 8b in the flange 8 and the recesses in the hub are opposite the recesses in the flange. The window-shaped free space formed by the recesses in the hub or between the shoulders 9a of the ring-shaped intermediate element and in the flange disc 8 each serve to hold in part the predamper energy accumulators 18.

The predamper energy accumulators 18 engage on their radially outer radial and circumferentially lying areas on the contact bearing areas 8b of the hub disc as well as on their radially inner radial and circumferentially lying areas on the inner contact bearing areas or faces 9c of the ring-shaped intermediate element.

The outer gearing of the hub and the inner gearing of the flange as well as the axial projections of the intermediate element are formed when the predamper energy accumulators are inserted in the embodiment according to the invention illustrated in the drawings, so that the turning play between the outer gearing of the hub and the inner gearing of the flange is less in the push direction than in the pull direction, ie the ratio of the turning play in the pull direction 21a to the turning play in the push direction 21b is greater than 1.

With a further design this ratio of the turning play in the pull direction 21a to the turning play in the push direction 21b is equal to 1 or also less than 1. As a result of the predamper springs being received in the window-shaped openings between the hub part 11 and the flange 8 and a possible relative rotation between the radially outer window area to the radially inner window area, turning of the hub part in relation to the flange and respectively turning of the flange in relation to the hub part can only be effected through applying force against the tension of the predamper energy accumulators 18.

This relative rotation can be carried out through a defined angular area which is defined by the toothed flank play.

In the present embodiment, with a different toothed flank play in the push or pull direction the predamper is then short-circuited if the inner gearing 8a of the flange moves into active contact with the outer gearing 11a of the hub and the predamper energy accumulators can be compressed no further and thus tensioned against a force in the circumferential direction.

An expedient design of the invention has on the faces 9c of the intermediate part 9 facing the predamper energy accumulators 18 additional holding means 20 in the form of projections which project at least partially into the inner areas of the predamper springs and secure the predamper springs against slipping in the axial direction.

This securement or hold against a possible slipping of the predamper energy accumulators favours a preassembly of the central predamper in manufacture since the intermediate element can already be fitted in advance with the predamper springs and can thus lead to a more cost-effective production of the clutch discs.

The intermediate element 9 has a conical face 9d on its axially opposite side axially in the direction of the hub outer gearing, ie the side which faces the entrainment disc 5. Opposite this first conical design of the side face of the intermediate element according to the invention is a likewise conical second counter face so that the conical first face of the intermediate element enters in flat surface contact with this second face. This second conical counter face is advantageously formed from the radially inner area of the entrainment disc 5 so that the inner face of the entrainment disc 5 is formed conical in its radially inner area 5a.This design of the conical counter face Sa according to the invention represents an advantageous design variation since this is formed out of the inner area of the entrainment disc 5 and thus no further component which supports the conical counter face 5a has to be mounted axially between the entrainment disc 5 and conical outer sleeve face 9d of the intermediate element 9.

The conical face 9d of the intermediate element 9 is designed as a predamper friction disc which acts under spring biasing opposite the counter face Sa. The friction damping between the first conical friction face 5a and the second conical friction face 9d can be made suitable by selection of the materials and/or surface structures through a possible prior treatment of same. The intermediate element 9 can advantageously be made from fibre-reinforced plastics.

In a spatial area which in relation to the flange is opposite the spatial area which receives the conical intermediate element 9, a friction disc 10 is received in the axial direction between the face of the hub gearing lla pointing in the axial direction and the counter disc 7 wherein this friction disc 10 is resiliently biassed by an energy accumulator 22 against an axially pointing face of the hub gearing, can be held rotationally secured on the counter disc, adjoins a counter friction face lld on the hub side and with relative movements between the friction disc 10 and this counter friction face lld exerts a friction action.

The radial extension of the circular ring shaped friction disc 10 is dimensioned so that the outer radius of the friction disc projects radially out over the radial area of its counter friction faces 11b and penetrates into the radial area of the radial extension of the predamper springs 18, so that the radially outer areas of the friction disc circumference serve as side support faces in the axial direction for the predamper springs 18, so that these predamper springs 18 which on the one hand adjoin radially inwards and outwards against boundaries of the receiving areas and on the other are held axially in the axial direction, in the direction of the entrainment disc, by the circular ring shaped intermediate element and in the axial direction, in the direction of the counter disc, by the circular ring shaped friction disc, so that the predamper springs remain in their window-shaped structural space and are not caused through the vibrations transferred to the clutch disc to fall out of the these structural spaces.

Through this expedient design it can be ensured that the predamper springs are held in their window-shaped recesses even under the influence of the pressurised forces acting on same in the circumferential direction since the pressurised springs in this state are only secured on one of their circumferentially placed end regions by the holding means 20 which are located on the intermediate ring projections 9a.

In the space between the flange and counter disc in the embodiment illustrated there is a further energy accumulator 19 which can be designed as a plate spring with circular ring shaped foundation body and radially inwardly pointing moulded areas. It can thereby be expedient if the energy accumulator 19 has a larger outer diameter than the energy accumulator 22 and the two energy accumulators cover one another at least in the partial areas of their axial and radial extension in the radial and axial direction.

As a result of this design feature it is possible to save structural space advantageously in the axial direction.

The radially outer ring-shaped area of the foundation body of the plate spring 19 is supported on the flange 8 and biases this against a specially shaped bearing area Sb of the entrainment disc. The radially inner moulded areas of the plate spring 19 are supported against the counter disc 7 and project at least in partial areas in recesses or moulded areas of the counter disc 7 which can be advantageous for the purpose of the rotationally secured holding of the plate spring 19 and the centring of the plate spring 19 relative to the rotary axis.

The tensioning of the plate spring 19 between the flange 8 and the counter disc 7 causes the counter disc 7 to be biased axially away from the flange 8. Since the entrainment disc 5 and counter disc 7 are connected together through spacer bolts 6 both rotationally secured and also fixed in the axial direction, as a result of the biasing of the counter disc the entrainment disc 5 is biased in the direction of the flange 8. This biasing of the entrainment disc 5 causes biasing of the entrainment disc in its radially inner area of its conical moulded areas 5a against the conical friction face 9d of the intermediate element 9.

By adapting the radially inner diameter of the intermediate element 9 to the radial outer face lle of the hub 11 and adapting a partial face of the intermediate element 9 to a further moulded area llf of the hub gearing lia the conical intermediate element 9, when biased in the axial direction, in the direction of the hub gearing, is axially supported on this moulded area llf and this has the advantage according to the invention that with a biasing of the friction face 9d of the intermediate element it is not possible for the intermediate element 9 to tilt about at least an axis which is not the rotational axis of the intermediate element and is at right angles to the axis of rotation of the intermediate element and thus the axis of rotation of the intermediate element 9 no longer coincides with the axis of rotation of the clutch disc.

With the design of the intermediate element and entrainment disc according to the invention the entrainment disc is tensioned with a spring loading or with a force biasing with its conical friction or slide face against the conical friction or slide face of the intermediate element and is automatically centred. A displacement of the axis of rotation of the entrainment disc relative to the axis of rotation of the hub and the intermediate element supported thereon, in a direction at right angles to the axis of rotation results with the design of the conical friction or slide faces according to the invention in an increased spacing between these faces and thus between the component parts 5, 9 supporting the conical faces.If a force action is exerted between these said parts 5,9 which biases the component parts towards each other then the axial distance between the said component parts 5, 9 decreases and as a result the distance between the axes of rotation of the hub and entrainment disc is reduced and the input part of the clutch disc is centred relative to the output part of the clutch disc in active connection with the gearbox.

The invention is not restricted to the embodiments described and illustrated but comprises in particular variations which can be formed by a combination of features and elements as well as functioning methods described in connection with the present invention and previously mentioned patent applications. Furthermore individual features or functioning methods described in connection with the figures can be taken alone to represent an independent invention.

The applicant reserves the right to claim as being essential to the invention further features which up until now have only been disclosed in the description or in connection the figures.

Claims

1. Torsion vibration damper more particularly in the drive train of a motor vehicle, with a pre-damping device having at least one energy accumulator of lower stiffness, and a main damping device having at least one energy accumulator of higher stiffness, more particularly for vehicle clutch discs, wherein the energy accumulators are operationally mounted between respective input and output parts of the predamping and main damping devices, the output part of the main damper being connected radially inside the main damper energy accumulator to a hub part with a torsional play existing over a certain area, and the predamping device being operationally connected on the output side with the hub part, for which the hub part and a flange part each have intermeshing teeth aligned towards each other and provided with circumferential play relative to each other and in the radial area of the teeth recesses are provided in both the flange part and in the hub part and a predamping energy accumulator is housed roughly half in each and at least one friction damping device is operationally mounted parallel to the predamping energy accumulators characterised in that an axially conical intermediate element, such as a plastics component provided between the hub part and an input part of the torsion vibration damper, for whose conical surface the input or hub part of the torsion vibration damper has a similar counter face, engages through each two axially protruding shoulders in each one of the recesses of the hub, and the predamper energy accumulator is provided between the shoulders.

2. Torsion vibration damper according to Claim 1 characterised in that the conical circular ring shaped intermediate element is mounted substantially radially in the area between the hub part and the inner gearing of the main damper flange.

3. Torsion vibration damper according to Claims 1 or 2 characterised in that on the circumference of the circular ring shaped intermediate element there is a regular arrangement of axial projections, arranged in pairs, and in the case of more than one pair of axially pointing projections on the intermediate element these are attached in the circumferential direction of the intermediate element.

4. Torsion vibration damper according to one of Claims 1 or 2 characterised in that the angles between each two pairs of axial projections on the circular ring shaped intermediate element arranged in pairs along the circumference of the circular ring shaped intermediate element are not the same size and, viewed circumferentially, are arranged irregular.

5. Torsion vibration damper according to Claims 1 to 4 characterised in that there is no rotational play between the axial projections of the intermediate element and the contact areas of the hub part provided for same.

6. Torsion vibration damper according to Claims 1 to 5 characterised in that there is rotational play between the axial projections of the intermediate element and the contact areas of the hub part provided for same.

7. Torsion vibration damper according to Claims 1 to 6 characterised in that the axial projections of the intermediate element arranged in pairs can each have holding means on the side faces which point towards each other in pairs in the circumferential direction.

8. Torsion vibration damper according to Claims 1 to 7 characterised in that the predamping energy accumulators are inserted with slight pretension in the recesses provided for same.

9. Torsion vibration damper according to any one of Claims 1 to 8 characterised in that on the side of the flange in the axial direction which is opposite the side in the axial direction on which the conical friction face of the intermediate element is mounted and between the flange and the side disc located on this side of the flange, such as an entrainment disc or counter disc, there are at least two axially resiliently tensioned energy accumulators, such as plate-spring like elements, which can be covered at least partially in the axial direction and/or in the radial direction so that the one energy accumulator having the larger outer diameter causes a resilient tensioning between the main damper flange and the one side disc connected rotationally secured to the input part of the torsion vibration damper, as well as the second energy accumulator with the smaller outer diameter causes a resilient tensioning between a circular ring shaped friction disc axially adjoining the hub and a side disc connected rotationally secured to the input part of the torsion vibration damper.

10. Torsion vibration damper according to any one of Claims 1 to 9 characterised in that the circular ring shaped energy accumulator, such as plate spring, with the larger outer diameter in its radially outer area resiliently biases the output part of the main damper, the flange, in the axial direction and a friction damping can be produced in this contact area or on this contact face between the plate spring and flange as a result of the contact pressure force exerted by the resilient tensioning.

11. Torsion vibration damper, more particularly according to any one of Claims 1 to 10 characterised in that the axially resiliently tensioned circular ring shaped energy accumulators, such as plate-spring like elements, are each constructed with a circular ring shaped foundation body and this circular ring shaped foundation body is provided with holding means in the radial direction which are aligned in the radial direction towards the axis of rotation of the plate springs and/or are directed in the radial direction away from the axis of rotation and engage on holding means provided for this, such as recesses in the side disc, to secure against rotation.

12. Torsion vibration damper according to any one of Claims 1 to 15 characterised in that the torsional play between the profile of the hub external gearing and the profile of the inner gearing of the output part of the main damper is asymmetrical, ie that the ratio between the torsional play in the pull direction and the torsional play in the push direction is greater or less than 1.

13. Torsion vibration damper according to any one of Claims 1 to 12 characterised in that the torsional play between the profile of the hub external gearing and the profile of the inner gearing of the output part of the main damper is symmetrical, ie the ratio between the torsional play in the pull direction and the torsional play in the push direction is equal to 1.

14. Torsion vibration damper according to any one of Claims 1 to 13 characterised in that the conical intermediate element and/or the circular ring shaped friction disc is/are made from friction or sliding material and/or coated with such material.

15. Torsion vibration damper substantially as herein described with reference to the accompanying drawings.