GB2160295A

GB2160295A - Torque-transmitting device

Info

Publication number: GB2160295A
Application number: GB08514927A
Authority: GB
Inventors: Wolfgang Reik
Original assignee: LuK Lamellen und Kupplungsbau GmbH
Current assignee: LuK Lamellen und Kupplungsbau GmbH
Priority date: 1984-06-12
Filing date: 1985-06-12
Publication date: 1985-12-18
Also published as: JPH0563650B2; JP2794017B2; JPH0754926A; FR2565645A1; JPH0754925A; JPH028531A; JPH0637920B2; JP3103057B2; JPH028532A; ES544072A0; JP3103055B2; JPH10227335A; FR2626636A1; FR2565645B1; AU4318285A; JPH10227334A; JPS6110120A; GB8514927D0; FR2626636B1; BR8502758A

Abstract

A torque-transmitting device has means for absorbing or compensating for rotary impulses by means of at least two gyratory masses (3,4) which are arranged coaxially with each other via a bearing (15) and are rotatable with respect to each other through a limited angle against the action of a damping device (13). One of the gyratory masses (4) has a friction surface which cooperates with a clutch disk (9). In order to increase the working life of the bearing (15) and consequently also to improve the operation of the torque- transmitting device, means (18) are provided between the friction surface of the gyratory mass (4) and the bearing (15) for reducing heat flow between the friction surface and the bearing. <IMAGE>

Description

SPECIFICATION Torque-transmitting device The invention relates to a torque-transmitting device having means for absorbing or compensating for rotary impulses, especially torque variations in an internal combustion engine, including at least two gyratory masses which are arranged coaxially with each other by means of a bearing unit and are rotatable with respect to each other through a limited angle against the action of a damping device, a first one of which gyratory masses can be connected to the internal combustion engine and the other, second, one of which can be connected to the input part of a gearbox and has a friction surface that cooperates with a clutch disc.

It has already been proposed, in connection with such torque-transmitting devices, to arrange the bearing unit directly between the two gyratory masses, so that, when a rolling bearing is used, one race ring is fixed for rotation with the first one of the gyratory masses and the other race ring is fixed for rotation with the other gyratory mass. Although a very good damping of the oscillations that occur between the internal combustion engine and the transmission line of a motor vehicle can be obtained with torquetransmitting devices of this kind, they have hitherto failed to find favour in the automobile industry because the working life of the bearing unit provided between the gyratory masses is too short.This bearing unit constitutes one of the critical points in such a device, since it becomes unserviceable after only a relatively short period of operation due to its unfavourable operational characteristics.

The basic object of the present invention is to provide a torque-transmitting device which, by comparison with previously proposed torque-transmitting devices of the kind initially referred to, functions better and has a longer working life, as well as being capable of being produced particularly more simply and economically.

According to the invention, this object is achieved in that a means is provided for at least reducing the heat flow from the friction surface to the bearing, so that the thermal loading of the bearing is reduced. Comprehensive investigations have of course shown that the thermal energy liberated during the operation of the friction clutch produces a thermal load on the bearing unit which in the long term is excessive. Especially when bearing units having a small clearance are used, it is possible that the differences of expansion or contraction due to the very rapid heating and cooling that occur between the individual component parts may lead to wear phenomena in the bearing unit, since the clearance is taken up and eliminated by the substantial temperature differences between the individual component parts of the bearing unit.

Moreover, the use of the means that are provided according to the invention enables overheating of the lubricant in the bearing, such as oil, grease or the like, from taking place, so that reliable lubrication of the bearing unit and hence also a longer working life thereof are always ensured.

The means whereby undue heating of the bearing unit is prevented may with advantage be constituted by an insulation arranged between the friction surface and the bearing unit.

It may be particularly advantageous if the insulation is located between the bearing-supporting part of the second gyratory mass, i.e.

between the part by which the second gyratory mass is supported via the bearing with respect to the first gyratory mass on the one hand and the bearing unit on the other hand.

Such an arrangement of the insulation may be advantageous, especially in the case of devices in which the bearing unit comprises a rolling bearing, since the insulation may then be located between the race ring or race rings which carry and are fixed for rotation with the second gyratory mass on the one hand and the supporting part which is provided on the said second gyratory mass and provides a seating for the reception of the bearing unit on the other hand.

There are a number of different materials that could be used for the production of insulations which will prevent overheating of the bearing unit. It may, however, be advantageous if such insulations are composed of a synthetic material, which, if necessary, may be fibre-reinforced, or of a ceramic material.

For the production of insulations of synthetic material, a thermosetting plastics material and especially a phenolic plastics material such as a laminated bakelized paper, or alternatively a thermoplastics material, such as for example poly-tetra-fluoro-ethylene, a polyimide or a polyamidimide may be used. It may also be appropriate to produce the insulation from a fibre-reinforced polycarbonate.

In particular, in a torque-transmitting device in which the said first one of the gyratory masses is provided with an axial projection which extends axially into a central recess in the said other gyratory mass and the bearing is located between the projection and the wall surface of the recess, it may be suitable for many different applications if the insulation is located between the wall surface of the central recess and the bearing. For other applications, in which the said first one of the gyratory masses also has a central, spigot-like projection that extends axially into a central recess in the other gyratory mass and the bearing unit is located between the projection and the wall surface of the recess, it may be suitable if the insulation is located between the spigot like projection and the bearing.

It may be particularly advantageous if the second gyratory mass, which may be connected to the input part of a gearbox, is formed with the central recess and the insulation is provided between the wall surface of the said recess and a race ring connected therewith. It may be appropriate if the inner race ring of the bearing is mounted on the projection and the outer race ring is fitted in the central recess, and supports the second gyratory mass via the insulation.

Various different procedures may be advantageous, depending on the choice of material, for fixing the insulation to the race ring which supports it. Thus, for example, the insulation may be sprayed over the bearing or sintered onto the appropriate race ring, or else, if insulating rings are provided which have a tubular part, these insulating rings may be pressed onto the bearing. A further advantageous possible way of introducing an insulation between the bearing and the corresponding gyratory mass consists in pre-mounting the bearing on the corresponding gyratory mass, the outer race ring being fitted in a recess having a diameter which is larger than the outside diameter of the said outer race ring and the clearance space between the wall surface of the recess and the outer race ring then being filled with a synthetic material which is poured or injected into it.

It may be particularly advantageous if the insulation is utilized at the same time as a seal for the bearing. Such an insulation and seal may with advantage be formed by at least one ring of L-shaped cross-section, one limb of which axially overlies and engages tightly round one of the bearing races and the other limb of which extends radially in the direction towards the other race ring. It is, moreover, suitable if the radially extending limb which forms the seal extends radially over at least part of that race ring which is not axially covered by the insulation, and bears axially against the last-mentioned race ring.

Although it may be appropriate for many applications if the insulation is formed by a single L-section ring, the axially extending limb of which extends at least approximately over the entire width of race ring, it may be particularly advantageous for other applications if the insulation is constituted by two rings of L-shaped cross-section which are fitted over one of the race rings from the two opposite sides thereof respectively.

In particular in torque-transmitting devices in which a rolling bearing is accommodated in a central recess in the gyratory mass which is provided with the friction surface, it may be particularly suitable if the insulating rings of Lshaped cross-section have-as viewed in crosssection-radially inwardly projecting limbs and are fitted over the outer race ring.

In order to ensure a reliable sealing of the bearing, it may be particularly advantageous if the radially extending limb of the insulating ring which serves for sealing the bearing is urged axially by a force accumulator in the direction towards the race ring which is radially covered by the said limb. Such a force accumulator may suitably be formed by a plate spring.

Furthermore, it may be appropriate if the Lsection insulating ring is so constructed and arranged that, when the said insulating ring is fitted over the bearing, the radially extending limb thereof is resiliently prestressed and consequently bears resiliently against the race ring over which is extends radially.

When a plate spring is used for resiliently loading the radially extending sealing limb of the insulation, it may be particularly suitable if the radially outer part of the plate spring is supported against the second gyratory mass, which may be connected to the input part of a gearbox, and its radially inner part acts against the end region of the radial limb of the sealing ring.

It may be particularly advantageous for the purposes of assembly, if the insulation has a tubular part which is pressed into the recess that is formed in one of the gyratory masses for accommodating the bearing. Depending on application, it may moreover be appropriate either first to press the insulation into the recess and then to press in the bearing, or instead first to fit the insulation over the bearing and then to press it together with the bearing into the recess. It may moreover be suitable if the tubular part of the insulation, which engages round the bearing, has-considered in an axial direction-parts of different thickness or diameter, so that only those parts which have a larger diameter or thickness are received as a press fit in the recess which accommodates the bearing.

When bearings are used which have a filling of lubricant, it may be particularly advantageous if an additional seal is provided between that limb of the L-section ring which axially overlies and engages round one of the race rings on the one hand and the said one of the race rings on the other hand, which additional seal prevents the lubricant from being able to escape between the insulation and the race ring, e.g. as a result of centrifugal forces. Such a seal may with advantage be formed by an O-ring. The seal may, moreover, be supported against the inner boundary wall surface of the axially extending limb of the insulation and be accommodated in a cutaway part, such as a chamfer or groove, in the outer race ring.

It may be appropriate if the seal is so arranged that it is clamped between the front end of the axially extending limb of the insulation and a shoulder on the outer race ring.

In order to ensure easier assembly, as well as to avoid uncertainty in the centring be tween the gyratory masses, due to manufacturing tolerances, it may be advantageous if an insulating ring of tapered or conical crosssection is arranged between the supporting region of the second gyratory mass and the bearing or the corresponding race ring. Moreover, the bearing and/or the supporting region may have a tapered or conical outer surface which matches the adjacent surface of the insulating ring.In order to ensure an automatic equalisation of the wear which may possibly occur, as well as a reliable centring and mounting of the bearing in the recess provided for its reception, it may be appropriate if the insulation ring of tapered or conical cross-section is subject to an axial prestressing force acting in the direction towards the convergence, so that it is wedged tightly between the wall surface of the receiving opening and the corresponding race ring. In order to ensure that the insulating ring is tightly wedged, it may be suitable if it is split, i.e. is open at its circumference.

Obviously an insulating ring of tapered or conical cross-section may also have a seal for the bearing, which may be constructed and arranged as already described and urged axially by a force accumulator in the direction towards the end surface of the race ring against which the said seal is supported.

The invention will be explained in greater detail with reference to Figs. 1 to 3, in which Figure 1 shows a torque-transmitting device according to the invention and Figures 2 and 3 show further arrangements according to the invention for reducing the heat flow between the friction surfaces and the bearing unit of a torque-transmitting device.

As is evident from Fig. 1, the device 1 for compensating for rotary impulses has a flywheel 2 which is divided into two gyratory masses 3 and 4. The gyratory mass 3 is fixed on a crankshaft 5 of an internal combustion engine, which is not otherwise shown, by means of fixing screws 6. A friction clutch 7 is fixed to the gyratory mass 4 by means which are not specifically shown. Between the pressure plate 8 of the friction clutch 7 and the gyratory mass 4 there is provided a clutch disk 9 which is mounted on the input shaft 10 of a gearbox which is not otherwise shown. The pressure plate 8 of the friction clutch 7 is urged by a diaphragm spring 12, which is rockably mounted on the clutch cover plate 11, in the direction towards the gyratory mass 4.The gyratory mass 4, and hence also the flywheel 2, can be coupled to and uncoupled from the input shaft 10 of the gearbox by operating the friction clutch 7.

Between the gyratory mass 3 and the gyratory mass 4 there are provided damping means in the form of a damping device 1 3 as well as a slipping clutch 14 connected in series therewith, which enable a limited relative rotation to take place between the two gyratory masses 3 and 4.

The two gyratory masses 3 and 4 are mounted for rotation relatively to each other by means of a bearing unit 1 5. The bearing unit 1 5 includes a rolling bearing in the form of a single-row ball bearing 16. The outer race ring 1 7 of the rolling bearing 1 6 is located within a bore 18 in the gyratory mass 4 and the inner race ring 1 9 of the rolling bearing 1 6 is mounted on a central pin 20 on the gyratory mass 3, which pin 20 extends axially away from the crankshaft 5 and into the bore 18.

The inner race ring 1 9 is engaged as a press fit on the pin 20 and is clamped axially between a shoulder 21 on the pin 20 or on the gyratory mass 3 and a retaining disk 22 which is secured against the end surface 20a of the pin 20 by means of screws 23.

Between the outer race ring 1 7 and the gyratory mass 4, there is provided a thermal insulation 24 which interrupts or at least reduces the heat flow to the bearing 1 6 from the friction surface 4a of the gyratory mass 4 that cooperates with the clutch disk 9. Thus, thermal overloading of the grease filling of the bearing, as well as excessive thermal distortion or undue expansion of the bearing, which could cause jamming of the balls 1 6a between the race rings 1 7 and 1 9 are prevented. In order to accommodate the insulation 24, the bore 1 8 in the gyratory mass 4 has a diameter which is greater than the outside diameter of the outer race ring 17, so that a radial gap is formed.

The insulation is formed by two rings 25, 26 of L-shaped cross-section which are fitted over the outer race ring 1 7 from the two opposite sides thereof respectively. The axially adjoining limbs 25a, 26a of the L-section insulating rings 25, 26 engage over or round the outer race ring 1 7. The radially inwardly projecting limbs 25b, 26b extend radially part way over the inner race ring 1 9 and are supported axially against the latter, so that they serve at the same time as a seal for the bearing 1 6. In order to ensure reliable sealing of the bearing 16, each of the radially extending limbs 25b, 26b, it urged by a respective plate spring 27 or 28 axially in the direction towards the corresponding end surface of the inner race ring 1 9. The plate spring 27 is supported at its radially outer edge against a shoulder on a disk 30 which is rigidly connected by bolts 29 to the second gyratory mass 4 and acts by means of its radially inner part against the end surface parts of the radial limb 25b of the insulating and sealing ring 25. Similarly, the plate spring 28 is supported at its radially outer edge against a shoulder on the gyratory mass 4 and acts by means of its radially inner part against the end surface parts of the radial limb 26b of the insulating and sealing ring 26.

For the assembly of the rings 25, 26 and of the bearing 16, it is advantageous, in the embodiment according to Fig. 1, if the rings are first pressed over the outer race ring 1 7 with their tubular part foremost and the bearing 1 6 with the rings 25, 26 pressed over it is then pressed into the bore or recess 1 8 in the gyratory mass 4. The bearing 1 6 is held against axial displacement with respect to the gyratory mass 4 in that it is clamped, with the interposition of the rings 25, 26, axially between a shoulder 31 on the gyratory mass 4 on the one hand and the disk 30 on the other hand.

The damping device 1 3 has two disks 30, 33 which are arranged one on each side of the flange 32 and are interconnected in axially spaced apart relationship by spacing bolts 29 so that they are fixed for rotation with each other. The spacing bolts 29 also serve for fixing the two disks 30, 33 to the gyratory mass 4. The disks 30, 33 and the flange 32 are formed with openings in which force accumulators in the form of coil springs 34 are accommodated. These force accumulators 34 oppose relative rotation between the flange 32 and the two disks 30, 33.

The damping device 1 3 moreover has a friction device 1 3a which is operative over the whole of the possible range of rotation between the two gyratory masses 3 and 4. The friction device 1 3a is located axially between the disk 30 and the gyratory mass 3 and has a force accumulator 35 formed by a plate spring which is held clamped between the disk 30 and a thrust ring 36, so that the friction ring 37 arranged between the thrust ring 36 and the gyratory mass 3 is compressed. The force exerted by the plate spring 35 on the disk 30 is received by the bearing 16.

The flange 32 forms on the one hand the input part of the damping device 1 3 and on the other hand the output part of the slipping clutch 14. The input part of this slipping clutch 14 is formed by two disks 38, 39, which are arranged in axially spaced apart relationship to each other and are fixed for rotation with the gyratory mass 3. The annular disk 39 is fixed to the gyratory mass 3 by means of rivets 40. The disk 38 has axial lugs 38a which are formed integrally on its outer circumference and engage in openings 41 in the disk 39 in order to prevent rotation of the disk 38 with respect to the disk 39. Radial projections 42 on the flange 32 are clamped axially between the disks 38, 39.For this purpose, the two disks 38, 39 are resiliently urged towards each other by a plate spring 43 which on the one hand is supported against the gyratory mass 3 and the other hand urges the disk 38 in the direction towards the disk 39. In the regions between the projections 42 on the flange 32, the disks 38, 39 are formed with axially aligned openings containing force accumulators 44 which act as buffer stops for the projections 42 on the flange 32 and hence limit the angle of rotation of the slipping clutch 14.

In the constructional variant shown in Fig.

2, a ball bearing 11 6, is once again used for mounting the gyratory mass 4 relatively to the gyratory mass 3, this ball bearing being arranged in a similar manner to the ball bearing 16 according to Fig. 1. The outer race ring 11 7 of the ball bearing 11 6 has chamfers 117a, 11 7b by means of which free spaces are formed between the race ring 11 7 and the L-shaped rings 125, 1 26 of insulating material which engage axially over it. Seals in the form of O-rings 145, 146 are provided in these free spaces. These O-rings 145, 146 prevent the bearing grease between the Lsection rings 125, 1 26 and the race ring 11 7 from being able to be forced out or to leak out.The chamfers 117a, 11 7b and O-rings 145, 146 are so matched with each other that the O-rings are resiliently deformed between the L-section rings 125, 1 26 and the chamfers 11 7a, 11 7b of the bearing 116.

As is furthermore evident from Fig. 2, the radial limbs 125b, 126 b of the L-section insulating or sealing rings 125, 1 26 are of reduced thickness compared with the axially extending limbs 125a 126a. On the radially inner end of each limb 125b, 1 26b there is formed a sealing lip 125c, 126c.

In the embodiment shown in Fig. 3, an insulating ring 225 of tapered or conical cross-section is arranged between the wall of the bore 1 8 in the gyratory mass 4, in which the bearing 216 is received, and the outer race ring 217. In the embodiment shown, both the outer surface and also the inner surface of the insulating ring 225 are tapered in an axial direction. It would, however, easily be possible to make only one of these main surfaces tapered.

The bore 218 is dimensioned so as to match the tapered outer surface of the insulating ring 225 and the outer surface of the race ring 21 7 so as to match the tapered inner surface of the said insulating ring 225. The insulating ring 225 is urged axially in the direction towards its convergent end by means of a plate spring 227 which is supported against the disk 230 which in turn is axially fixed with respect to the gyratory mass 4. The insulating ring 225 has a radially inwardly extending part 225b which seals the bearing by pressing axially against the inner race ring 219. For sealing the bearing on the other side, there is provided a ring 226, composed of insulating material, which is clamped axially between the outer race ring 217 and a shoulder 231 on the gyratory mass 4 by the action of the plate spring 227.

The sealing ring 226 has a lip 226b which bears axially against the inner race ring 219.

In the embodiments according to Figs. 1 and 2, plate springs 27, 28 are provided which urge radially extending sealing parts 25b, 26b and 125b, 1 26b in the axial direction towards the race ring 19 or 11 9. By a suitable choice of material it would be made possible, however, for the rings 25, 26 and 125, 1 26 to be so formed instead that, when these rings 25, 26 or 125, 126 are assembled, their radial limbs 25b, 26b or 1 25b, 1 26b are resiliently deformed in such a manner that they abut axially against the race ring 1 9 or 11 9 in a prestressed condition. The use of this feature would enable the plate springs 27, 28 to be dispensed with.

In the embodiments described so far, the insulation is constituted by additional rings which are arranged between the second gyratory mass 4 and bearing 16, 116, 216.

According to further embodiments (not shown), the insulation may, however, be sprayed or sintered onto the bearing 16, 116, 216 or onto the race ring 17, 117, 217, so that the insulation is practically integral with the bearing. Likewise, the insulation could instead be applied over the wall surface of the recess 18, 118, 218.

When using bearings which are provided for example with sealing rings, such as are offered for sale by bearing manufacturers, it is furthermore possible to pre-mount the bearing 1 6 on the gyratory mass 4, by inserting and fixedly mounting the outer race ring 1 7 centrally in the recess 18, which has a diameter larger than the outside diameter of the said race ring 17, and pouring or injecting a synthetic or plastics material into the free space between the wall surface of the recess 18 and the race ring 17.

Claims

1. Torque-transmitting device having means for absorbing or compensating for rotary impulses, and especially torque variations in an internal combustion engine, including at least two gyratory masses which are arranged coaxially with each other by means of a bearing unit and are rotatable with respect to each other through a limited angle against the action of a damping device, a first one of which gyratory masses can be connected to the internal combustion engine and the other, second, one of which can be connected to the input part of a gearbox, and has a friction surface that cooperates with a clutch disk, characterised in that a means (24; 125, 126; 225, 226) is provided for at least reducing the heat flow from the friction surface (4a) to the bearing unit (15).

2. Torque-transmitting device according to claim 1, characterised in that the said means is constituted by an insulation arranged between the friction surface (4a) and the bearing unit (15).

3. Torque-transmitting device according to claim 1 or 2, characterised in that the insulation is located between the bearing supporting part (18, 118, 218) of the second gyratory mass (4) and the bearing (16, 116, 216).

4. Torque-transmitting device according to one of claims 1 to 3, in which the bearing unit is constituted by a rolling bearing (16, 116, 216), characterised in that the insulation (24; 125, 126; 225, 226) is located between the race ring(s) (17, 117, 21 7) which carries or carry and is or are fixed for rotation with the second gyratory mass (4) on the one hand and the seating surface (18, 118, 218) which is provided in the said second gyratory mass (4) for the reception of the bearing unit on the other hand.

5. Torque-transmitting device according to one of claims 1 to 4, characterised in that the insulation (24; 125, 126; 225, 226) is composed of a synthetic material.

6. Torque-transmitting device according to claims 1 to 4, characterised in that the insulation (24; 125, 126; 225, 226) is composed of a ceramic material.

7. Torque-transmitting device according to claims 1 to 5, characterised in that the insulation (24; 125, 126; 225, 226) is composed of a thermosetting material, e.g. for example a phenolic plastics material such as laminated bakelized paper.

8. Torque-transmitting device according to claims 1 to 5, characterised in that the insulation (24; 125, 126; 225, 226) is composed of a thermoplastic material such as for example poly-tetra-fluoro-ethylene, a polyimide, or a polyamidimide.

9. Torque-transmitting device according to claims 1 to 5, characterised in that the insulation (24; 125, 126; 225, 226) is composed of a fibre-reinforced polycarbonate.

10. Torque-transmitting device according to one of claims 1 to 9, in which the first one of the gyratory masses has an axial projection which extends axially into a central recess in the other gyratory mass and the bearing unit is located between the projection and the wall surface of the recess, characterised in'what the insulation (24; 125, 126; 225, 226) is located between the wall surface of the central recess (18, 118, 218) and the bearing (16, 116,216).

11. Torque-transmitting device according to one of claims 1 to 9, in which the first one of the gyratory masses has a central, spigotlike projection which extends axially into a central recess in the other gyratory mass and the bearing unit is located between the projection and the wall surface of the recess, characterised in that the insulation is located between the spigot-like projection and the bearing.

1 2. Torque-transmitting device according to at least one of the preceding claims, characterised in that the second gyratory mass (4), which may be connected to the input part (10) of a gearbox, is formed with the central recess (18, 118, 218) and the insulation (24; 125, 126; 225, 226) is located between the wall surface of the said recess (18, 118, 218) and a race ring (17, 117, 217) connected therewith.

1 3. Torque-transmitting device according to one of claims 1 to 12, characterised in that the inner race ring (19, 119, 219) of the bearing (16, 116, 216) is mounted on the projection (20) and the outer race ring (17, 117, 217) is fitted in the central recess (18, 118, 218) and supports the second gyratory mass (4) via the insulation (24; 125, 126; 225, 226).

14. Torque-transmitting device according to one of claims 1 to 13, characterised in that the insulation is sprayed over the bearing.

1 5. Torque-transmitting device according to one of claims 1 to 13, characterised in that the insulation is sintered onto the bearing.

16. Torque-transmitting device according to one of claims 1 to 13, characterised in that the insulation (24; 125, 126) is pressed onto the bearing (16, 116).

1 7. Torque-transmitting device according to at least one of the preceding claims, characterised in that bearing (16) is premounted on one of the gyratory masses (4), the outer race ring (17) being accommodated in a recess (18) having a diameter which is larger than the outside diameter of the outer race ring (17) and the space between the wall surface of the recess (18) and the outer race ring (17) being filled with a synthetic material that has been poured or injected into it.

1 8. Torque-transmitting device according to at least one of the preceding claims, characterised in that the insulation (24; 1 25, 126; 225, 226) serves at the same time as a seal for the bearing (16, 116, 216).

1 9. Torque-transmitting device according to one of claims 1 to 18, characterised in that the insulation (24; 125, 126; 225, 226) has a seal (25b, 26b; 125b, 126b; 225b, 226b) for the bearing (16, 116,216) formed on it.

20. Torque-transmitting device according to one of claims 1 to 19, characterised in that the insulation (24; 125, 126; 225, 226) is formed by at least one ring (25, 26) of Lshaped cross-section one limb (25a, 26a; 125a, 126a, 225a) of which axially overlies and engages tightly around one of the bearing races (17, 117, 217) and the other limb (25b, 26b; 125b, I26b; 225b) of which extends radially in the direction towards the other race ring (19, 119, 219).

21. Torque-transmitting device according to claim 20, characterised in that the radially extending limb (25b, 26b; 125b, 126b; 225b) of the L-section insulation (24; 1 25, 126; 225) extends radially over at least part of that race ring (19, 119, 219) which is not axially covered by the insulation and bears axially against the last-mentioned race ring (19, 119, 219).

22. Torque-transmitting device according to one of claims 1 to 21, characterised in that the insulation is constituted by two rings (25, 26; 125, 126) of L-shaped cross-section which are fitted over one of the race rings (17; 11 7) from the two opposite sides thereof respectively.

23. Torque-transmitting device according to one of claims 1 to 22, characterised in that the insulating rings (25, 26; 125, 126; 225) of L-shaped cross-section have-as viewed in cross-section- radially inwardly projecting limbs (25b, 26b; 125b, 126b; 225b) and are fitted over the outer race ring (17, 117, 217).

24. Torque-transmitting device according to one of claims 1 to 23, characterised in that the radially projecting limb (25b, 26b; 125b, 1 26b; 225b) of each insulating ring (25, 26; 125, 126; 225) is urged axially by a force accumulator (27, 28, 227) in the direction towards the race ring (19, 119, 219) which is radially covered by the said limb.

25. Torque-transmitting device according to claim 24, characterised in that the force accumulator is constituted by a plate spring (27, 28, 227).

26. Torque-transmitting device according to claim 24 or 25, characterised in that the plate spring (27, 28) is supported by means of its radially outer part against the second gyratory mass (4), which may be connected to the input part (10) of a gearbox, and acts by means of its radially inner part against the end part of the radial limb (25b, 26b) of a sealing ring (25, 26).

27. Torque-transmitting device according to at least one of the preceding claims, characterised in that the insulation (25, 26; 125, 126) has a tubular part (25a, 26a; 125a, 126a) which is pressed into the recess (18, 11 8) formed in one (4) of the gyratory masses and accommodates the bearing (16, 116).

28. Torque-transmitting device according to claim 27, characterised in that the insulation (24) is first fitted over the bearing (16, 11 6) and is then pressed together with the latter into the recess (1 8, 11 8) in one of the gyratory masses (4).

29. Torque-transmitting device according to one of claims 1 to 28, characterised in that the tubular part of the insulation, which engages round the bearing has-considered in an axial direction-parts of different thickness or diameter, so that only those parts which have a larger diameter or thickness are received as a press fit in the recess which accommodates the bearing.

30. Torque-transmitting device according to one of claims 1 to 29, characterised in that a seal (145, 146) is provided between that limb (125a, 11 6a) of the L-section ring (125, 126) which axially overlies and engages round one (11 7) of the race rings on the one hand and the said one (11 7) of the race rings on the other hand.

31. Torque-transmitting device according to claim 30, characterised in that the seal is formed by an O-ring (145, 146).

32. Torque-transmitting device according to claim 29 or 30, characterised in that the seal (145, 146) is supported against the inner boundary wall surface of the axially extending limb (125a, 126a) of the insulation (125, 126) and is accommodated in a cut-away part, such as a chamfer or groove in the outer race ring (117).

33. Torque-transmitting device according to claim 30 or 31, characterised in that the seal is clamped between the front end of the axially extending limb of the insulation and a shoulder on the outer race ring.

34. Torque-transmitting device according to at least one of the preceding claims, characterised in that an insulating ring (225) of tapered or conical cross-section is located between the supporting region (218) of the second gyratory mass (4) and the bearing (216).

35. Torque-transmitting device according to claim 33, charactersed in that the bearing (216) and/or the supporting region (218) has a tapered or conical surface which matches the adjacent surface of the insulating ring.

36. Torque-transmitting device according to one of claims 33 or 34, characterised in that the insulating ring (225) of tapered or conical cross-section is subject to an axial prestressing force acting in the direction towards the convergence.

37. Torque-transmitting device according to one of claims 33 to 35, characterised in that the insulating ring is split, i.e. is open at its circumference.

38. Torque-transmitting device according to one of claims 33 to 36, characterised in that the insulation (225) has formed on it a seal (225b) for the bearing (216) and is constructed and arranged according to at least one of claims 20 to 26.