Transmission for a motor vehicle with a friction clutch having a clutch disc with torsionally locked friction ring

A clutch disc with a basic friction device, which can have a corresponding friction ring with axial projections that torsionally lock with the toothing of the hub, for transmission of the torque to the hub disc.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to friction clutches and more particularly 
to friction clutch discs. 
2. Background Information 
German Laid Open Patent Application No. 3 921 283, which corresponds to 
U.S. Pat. No. 5,016,744 entitled "Clutch Disc for a Friction Clutch", 
discloses such a clutch disc. On that clutch disc, there is a basic 
friction device, which is located between the end surface of the hub 
toothing and the one cover plate. It consists of a friction ring which is 
in direct contact with the toothing, and a lock washer between the 
friction ring and the cover plate. 
Basic friction devices of this type are tuned so that they generate the 
friction force in the idle range. But the range of fluctuation for the 
friction force generated by such a configuration is too great for 
particularly difficult tunings. With such a design, it cannot be 
guaranteed that the same friction surface will always act to apply the 
friction. In particular, it is easily possible for the friction surface to 
change, namely from the toothing of the hub to the friction ring, from the 
friction ring to the spring, or from the spring to the cover plate. Even 
if the coefficient of friction of the friction ring in relation to steel 
is lower than the coefficient of friction for steel-on-steel, if there is 
any surface roughness, the friction surfaces can occur between the lock 
washer and the cover plate, at least temporarily. 
The change of the friction surface, which occurs in known clutch assemblies 
has a very significant disruptive effect on idle tuning in sensitive 
vehicles. 
OBJECT OF THE INVENTION 
The object of the present invention is therefore to eliminate the 
disadvantages of known clutch assemblies at a reasonable expense. 
SUMMARY OF THE INVENTION 
The invention teaches that this object can be achieved by means of 
characteristics discussed hereinbelow wherein a torsional locking of the 
friction ring and hub is provided. As a result of the torsional locking of 
the friction ring in relation to the hub, it can be stated from the outset 
that the friction surfaces used must lie either between the friction ring 
and the spring or between the spring and the cover plate. It can also be 
assumed that when the surfaces of the friction ring, spring and cover 
plate are correctly manufactured, the friction surface will be between the 
friction ring and the spring, because that is where the lower coefficient 
of friction is. At least after the break-in or run-in process, at this 
point of separation, it is guaranteed that the friction surface used will 
be between the friction ring and the spring, since the friction ring 
essentially cannot move in relation to the hub due to the torsional 
locking. It is particularly advantageous to also use the toothing which is 
already present on the hub for the torsional locking of the friction ring. 
For this purpose the friction ring can have at least one axial projection 
distributed at the circumference of the friction ring to absorb the 
torque, and avoid the problem of pitch error. 
The invention also teaches that the contour of the first projections can be 
essentially the same as the contour of the toothing. In this manner, it 
can essentially be guaranteed that the surface pressure during the 
generation of the moment of friction is reduced to a minimum. 
It has also proven very advantageous if the first projections preferably 
run conically in the axial direction, namely becoming narrower as they 
project away from the base body of the friction ring. A very simple 
installation process is thereby possible, since the conical projections 
can be more easily threaded into the toothing of the hub. In the vicinity 
of the base body, from which the projections extend, the projections can 
be designed to be fully stress-bearing in relation to the toothing of the 
hub, so that preferably no clearance or play can occur in the 
circumferential direction. 
In accordance with an additional characteristic feature of the invention, 
there can be second axial projections distributed over the circumference 
of the friction ring, which second axial projections have a smaller 
circumferential dimension than the gaps in the external toothing. These 
additional projections do not cause interference during the assembly 
process, and as a result of their special configuration, they cannot cause 
problems as a result of pitch errors. They are used only to protect 
against relative torsional displacement in relation to the hub, in the 
event of wear of the first axial projections. 
The manufacturing tolerances of the second projections can therefore be 
relatively large, at least in the circumferential direction. 
An additional simplification of the basic friction device can be achieved 
by making the friction ring with its base body, in circumferential areas 
adjacent the first axial projections, corrugated in the axial direction, 
so that the addition of a spring is unnecessary. Such a configuration has 
the advantage of a smaller number of components, easier assembly and the 
guarantee of a constant basic friction, since it is guaranteed that the 
friction surface will always be between the axially corrugated areas of 
the friction ring and the cover plate. 
The base body, on the circumference between the projections, is thereby 
provided with corrugated crests which project in the opposite axial 
direction from the projections and have a flat surface area. The addition 
of the flat surface area can essentially guarantee that the surface 
pressure of the contact between the corrugated crests and the cover plate 
will not drop below a specified value. 
In one embodiment of the clutch disc, the invention proposes that a first 
hub disc for the idle spring device be fastened on one side of the 
external toothing of the hub, and that the guide element of the cover 
plate corresponding to the first hub disc is in contact with the first hub 
disc by means of an axially oriented leg. The axially spring mounted 
friction ring is preferably located on the opposite side between the cover 
plate and the end surface of the toothing, and the second hub disc is 
located between the friction ring and the first hub disc of the idle 
spring device. In this embodiment, the base friction is generated both by 
means of the friction ring and by means of the axially-oriented leg of the 
guide element on the opposite side, whereby both of the components 
participating in the generation of the friction force are locked to 
another component by means of a positive fit. Thus the friction surfaces 
are clearly defined, and the basic friction can be precisely tuned. 
Moreover, the toothing already present on the hub can also be used for the 
torsional locking of the friction ring, namely in the area in which the 
hub toothing it is not occupied by the toothing of the second hub disc. 
Thus there is a particularly simple basic friction device for clutch discs 
of this type, the effect of which can be regulated with precision. This 
orientation in the axial direction also conserves a great deal of space. 
One aspect of the invention resides broadly in a friction clutch for a 
transmission, in particular a transmission for a motor vehicle, the 
friction clutch comprising a clutch disc, the clutch disc comprising: a 
hub; the hub defining an axis of rotation; the hub comprising a hub disc 
disposed concentrically about the hub; the hub disc comprising a first 
side and a second side; a first cover plate disposed at the first side of 
the hub disc; the first cover plate comprising a plurality of windows 
disposed within the first cover plate; a second cover plate disposed at 
the second side of the hub disc; the second cover plate comprising a 
plurality of windows disposed within the second cover plate; the hub being 
configured to be torsionally locked on a drive shaft; the hub disc 
comprising a plurality of windows disposed within the hub disc; ones of 
the plurality of windows of the first cover plate, the second cover plate, 
and the hub disc being aligned with one another; a plurality of spring 
actuators disposed within the ones of the plurality of windows of the 
first cover plate, the second cover plate, and the hub disc; friction 
linings; the friction linings being disposed on one of the first cover 
plate and the second cover plate; a guide element being disposed between 
the first cover plate and the hub to serve as an axial stop for 
positioning the first cover plate in relation to the hub; the hub 
comprising a plurality of teeth extending radially outward from the hub; a 
plurality of spaces being disposed between and defined by ones of the 
plurality of teeth of the hub; the hub disc comprising a plurality of 
teeth extending radially inward from the hub disc; a plurality of spaces 
being disposed between and defined by ones of the plurality of teeth of 
the hub disc; ones of the plurality of teeth of the hub disc being engaged 
between ones of the plurality of teeth of the hub in ones of the plurality 
of spaces between ones of the plurality of teeth of the hub; friction 
means being disposed along the second cover plate; the friction means for 
providing a friction surface adjacent the hub; the friction means 
comprising a friction ring; the friction ring disposed concentrically 
about the axis of rotation; the friction ring comprising a ring-shaped 
base body; the base body having an axial direction substantially parallel 
to the axis of rotation and a circumferential direction about the axis of 
rotation; at least one first axial projection being disposed along the 
base body; the at least one first axial projection substantially 
projecting in the axial direction; the at least one first axial projection 
being disposed substantially tightly in the circumferential direction 
within one of the plurality of spaces between adjacent ones of the 
plurality of teeth of the hub; spring means; the spring means being 
disposed between the second cover plate and the friction ring; and the 
spring means being disposed to bias the friction ring towards the teeth of 
the hub. 
Another aspect of the invention resides broadly a transmission, in 
particular for a motor vehicle, a friction clutch, said friction clutch 
comprising a clutch disc, said clutch disc comprising: a hub; the hub 
defining an axis of rotation; the hub comprising a hub disc disposed 
concentrically about the hub; the hub disc comprising a first side and a 
second side; a first cover plate disposed at the first side of the hub 
disc; the first cover plate comprising a plurality of windows disposed 
within the first cover plate; a second cover plate disposed at the second 
side of the hub disc; the second cover plate comprising a plurality of 
windows disposed within the second cover plate; the hub being configured 
to be torsionally locked on a drive shaft; the hub disc comprising a 
plurality of windows disposed within the hub disc; ones of the plurality 
of windows of the first cover plate, the second cover plate, and the hub 
disc being aligned with one another; a plurality of spring actuators 
disposed within the ones of the plurality of windows of the first cover 
plate, the second cover plate, and the hub disc; friction linings; the 
friction linings being disposed on one of the first cover plate and the 
second cover plate; a guide element being disposed between the first cover 
plate and the hub to serve as an axis stop for positioning the first cover 
plate in relation to the hub; the hub comprising a plurality of teeth 
extending radially outward from the hub; a plurality of spaces being 
disposed between and defined by ones of the plurality of teeth of the hub; 
the hub disc comprising a plurality of teeth extending radially inward 
from the hub disc; a plurality of spaces being disposed between and 
defined by ones of the plurality of teeth of the hub disc; ones of the 
plurality of teeth of the hub disc being engaged between ones of the 
plurality of teeth of the hub in ones of the plurality of spaces between 
ones of the plurality of teeth of the hub; friction means being disposed 
along the second cover plate; the friction means for providing a friction 
surface adjacent the hub; the friction means comprising a friction ring; 
the friction ring disposed concentrically about the axis of rotation; the 
friction ring comprising a ring-shaped base body; the base body having an 
axial direction substantially parallel to the axis of rotation and a 
circumferential direction about the axis of rotation; at least one first 
axial projection being disposed along the base body; the at least one 
first axial projection substantially projecting in the axial direction; 
the at least one first axial projection being disposed substantially 
tightly in the circumferential direction within one of the plurality of 
spaces between adjacent ones of the plurality of teeth of the hub; spring 
means; the spring means being disposed between the second cover plate and 
the friction ring; and the spring means being disposed to bias the 
friction ring towards the teeth of the hub. 
Yet another aspect of the invention resides broadly in a clutch disc for a 
friction clutch, the clutch disc comprising: a hub; the hub defining an 
axis of rotation; the hub comprising a plurality of teeth extending 
radially outward from the hub; a plurality of spaces disposed between and 
defined by ones of the plurality of teeth of the hub; a hub disc; the hub 
disc disposed about the hub concentrically; the hub disc comprising a 
plurality of teeth extending radially inward from the hub disc; ones of 
the plurality of teeth of the hub disc being engaged between ones of the 
plurality of teeth of the hub in ones of the plurality of spaces between 
ones of the plurality of teeth of the hub; friction means; the friction 
means for providing a friction surface adjacent the hub; the friction 
means comprising a friction ring disposed concentrically about the axis of 
rotation; the friction ring comprising a ring-shaped base body; the base 
body having an axial direction substantially parallel to the axis of 
rotation and a circumferential direction about the axis of rotation; at 
least one first axial projection disposed along the base body and 
substantially projecting in the axial direction; and the at least one 
first axial projection configured to be and being disposed substantially 
tightly in the circumferential direction within one of the spaces between 
adjacent ones of the plurality of teeth of the hub.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a clutch disc 1 and its overall installation. The clutch disc 
is oriented concentrically with an axis of rotation 3, and consists of a 
hub 2, on which at least two cover plates 7 and 8 are radially guided, 
e.g. by means of a guide element 13 located on the cover plate 7. Both 
cover plates 7 and 8 are preferably locked together and held at a 
specified distance from one another (not shown), and the cover plate 7 can 
preferably have friction linings 9 on its radial outside. Axially between 
the two cover plates 7 and 8, there will generally be a hub disc 4 which 
points radially inward, and which can be torsionally locked in relation to 
the hub 2 by means of a toothing. The hub 2 preferably has an external 
toothing 6, and the hub disc 4 preferably has an internal toothing 5. In 
windows 10 of the hub disc 4 and in windows 11 of the cover plates 7 and 
8, there can generally be mounted springs 12, which springs 12 are 
compressed when torque is transmitted by the clutch disc 1, and thus 
guarantee a relative torsion between the cover plates 7 and 8 with the 
friction linings 9 on one hand, and the hub disc 4 with the hub 2 on the 
other hand, to reduce the torsional oscillations. In this case, there can 
also preferably be an idle spring device, which consists of the hub disc 
26 with the cover plates 27 and 28 located on both sides, and springs 
which are not shown in FIG. 1, but which are located between the hub disc 
26 and the cover plates 27 and 28 in corresponding windows. One possible 
configuration of springs 26a and is illustrated in FIG. 1a, wherein the 
springs 26a are preferably located between the hub disc 26 and the cover 
plates 27 and 28 in corresponding windows. 
The hub disc 26 is can preferably be rigidly connected to the hub 2, and 
the two cover plates 27 and 28 can preferably be torsionally locked to the 
hub disc 4. In this case of the addition of an idle spring device, it can 
be necessary to have some clearance or play between the hub disc 4 with 
its toothing 5 on the circumference and the toothing 6 on the hub 2. The 
idle spring device is preferably active inside this circumferential 
clearance. It is also possible, however, to realize the present invention 
on a clutch disc which does not have an idle spring device, in which case 
the toothings 5 and 6 would be designed without clearance on the 
circumference. Different friction devices can also be located in the 
clutch disc 1, namely a friction device for the load range, identified in 
the drawing by the number 24, and if necessary an additional friction 
device 25. These friction devices are known from the prior art, and are 
therefore not described here in any additional detail. 
There is also a basic friction device 15, which is active both in the idle 
range and also in the load range, and to which special attention should be 
paid in terms of tuning. In this case, the friction device 15 preferably 
has an axially oriented leg 14 of the guide element 13 in the cover plate 
7, and a friction ring 16 between the external toothing 6 of the hub 2 and 
the other cover plate 8, which friction ring can preferably be supported 
by a spring 29, e.g. in the form of a corrugated spring which is also in 
contact with the cover plate 8. The friction ring 16 can thereby be 
torsionally locked to the hub 2, in a manner which is described in greater 
detail below, to achieve a clear definition of the friction surface on the 
side of the assembly defined by cover plate 8. The spring 29 is tensioned 
by means of the two cover plates 8 and 7, which are preferably locked 
together, and by the guide element 13 on the hub disc 26 of the idle 
spring device, when such device is fully assembled. 
Further, the friction ring 16 can preferably be torsionally locked to the 
hub 2 in a manner discussed below, which torsional locking preferably 
ensures that the friction surface 16a will remain between the friction 
ring 16 and the spring 29, as illustrated in FIG. 1a. 
On the side defined by cover plate 7, the definition of the friction 
surface between the leg 14 of the guide element 13 and the hub disc 26 is 
clear. 
In other words, according to FIG. 1a, on the side opposite the friction 
ring 16, that is, the side defined by cover plate 7, the friction surface 
14a is preferably located between the leg 14 of the guide element 13 and 
the hub disc 26. 
FIGS. 2 and 3 illustrate one embodiment of the friction ring 16. The 
friction ring 16 can preferably have a base body 18, which is preferably 
circular in shape and which can be installed in the clutch disc 1 
concentrically with the axis of rotation 3. The base body 18, at at least 
two points distributed over the circumference, can preferably have 
axially-oriented first projections 20, the contours of which are designed 
so that they can be engaged in the tooth spaces of the toothing 6 of the 
hub 2 in the axial direction, and can preferably be tuned to one another 
so that there can preferably be no clearance in the circumferential 
direction. The inclusion of two axial projections 20 is advantageous 
because no pitch errors can occur in the circumferential direction which 
could interfere with the precise installation of the friction ring 16. 
These axial projections 20 of the friction ring 16 can also advantageously 
be conical in the axial direction, as shown in FIG. 4, so that during the 
installation of the friction ring 16, the friction ring 16 can be easily 
threaded into the toothing 6 of the hub 2. The circumferential size of 
these axial projections 20--shown as dimension X--can preferably be such 
that in the base region, i.e. in the vicinity of the transition from the 
projection 20 to the base body 18, as described more fully below, it can 
be essentially be guaranteed that there is preferably no clearance, or 
virtually no clearance, in relation to the tooth spaces of the toothing 6 
of the hub 2. The circumferential contour of these axial projections 20 
can be oriented to the contour of the tooth spaces of the toothing 6. The 
result is a low surface load on the circumference. 
In other words, as illustrated by FIGS. 2 and 3, the first projections 20 
are preferably designed to fit into the tooth spaces of the external 
toothing 6 of the hub 2, in the axial direction. The external toothing 6 
of the hub 2, and the first projections 20 are preferably designed to 
interlock without any clearance or play in the circumferential direction, 
or possibly without any substantial clearance or play in the 
circumferential direction, or in the region between points 18a and 18b, in 
relation to the tooth spaces 6a of the hub 2, as illustrated in FIG. 4a. 
That is, points 18a and 18b will each preferably be in contact with a 
tooth surface of a tooth 6. The circumferential size of the first 
projections 20, shown in FIG. 4 as X, preferably ensures that the first 
projections 20 interlock with the external teeth 6 of the hub 2 without 
any, or without any substantial clearance or play in the circumferential 
direction, or between points 18a and 18b. 
In addition, FIG. 3a shows an exploded view, in partial section, of the 
preferable engagement, or interlocking of the friction ring 16, hub 2, and 
the hub disc 4. As illustrated in FIG. 3a, at least one first axial 
projection 20 can preferably interlock with at least one tooth space 6a, 
which tooth space 6a is preferably located between and defined by two 
adjacent external teeth 6 of the hub 2. Further, at least one first axial 
projection 20 can preferably be disposed substantially tightly in the 
circumferential direction within a tooth space 6a. The internal teeth 5 of 
the hub disc 4 can also preferably interlock with the tooth spaces 6a 
located between and defined by two adjacent external teeth 6 of the hub 2. 
As shown in FIG. 3a, the first axial projection 20 and an internal tooth 5 
preferably share the same tooth space 6a. 
It is possible to have additional second axial projections 21 on the 
circumference of the friction ring 16. The number of these additional 
second axial projections 21 can range from a single second projection 21 
up to the maximum number of second axial projections 21 needed to fill all 
of the teeth spaces 6a. These second axial projections 21 can preferably 
be designed as illustrated in FIG. 5, i.e. they are defined 
circumferentially by the dimension Y, which can preferably be smaller than 
the dimension X illustrated in FIG. 4. On one hand, this prevents pitch 
errors from causing problems during the installation of the friction ring 
18, and on the other hand, it guarantees that if wear occurs to the first 
axial projections 20 in the circumferential direction, the additional 
axial projections 21 will still be able to transmit the force. Also, for 
production purposes, it is possible to keep the tolerances for the 
dimension Y of the projections 21 larger than for the projections 20, as 
illustrated in FIG. 4, thereby reducing manufacturing costs of such a 
friction ring 16. 
In other words, should any wear occur to the first axial projections 20 in 
the circumferential direction or in the region between 18a and 18b, as 
illustrated in FIG. 4a, at least one of the additional axial projections 
21 will still be able to transmit the force or torque. 
In addition, according to FIG. 5, the second axial projections 21 can 
preferably be non-conical in shape in the axial direction, as opposed to 
the conical shape of the first axial projections 20, as shown in FIG. 4. 
In another embodiment the second axial projections 21 may be tapered in a 
manner similar to first axial projections 20, to provide the required fit 
between the second axial projections 21 and the external toothing 6 of the 
hub 2. 
A variant embodiment of a friction ring is illustrated in FIGS. 6 and 7. 
The friction ring 17 used here, in terms of its axial projections 20, is 
the same as the friction ring 16 illustrated in FIGS. 2 to 4, but the base 
body 19 here is corrugated, or bent in the axial direction. In the 
circumferential areas which are located between the projections 20, the 
base body 19 can have corrugation crests which project toward the cover 
plate 8, which cover plate 8 is illustrated in FIG. 1. The corrugation 
crests 22 each preferably have a flat surface area 23. This presence of 
corrugation crests 22, and the resulting axial elastic action of the 
friction ring 17, provides the axial spring force necessary to position 
the friction ring 17. The friction ring 17 can preferably be installed in 
the axial direction between the ends of the toothing 6 and the cover plate 
8 under an axial prestress, so that the spring 29 shown in FIG. 1 can be 
eliminated. Naturally, the second axial projections 21 added to the 
friction ring 16 can also be present with the friction ring 17. When the 
friction ring 17 is installed, the second axial projections 21 are then at 
least partly engaged in the toothing 6 under axial prestress. 
One feature of the invention resides broadly in the clutch disc for a 
friction clutch in the drive train of a motor vehicle, consisting of a hub 
with a hub disc located concentrically with an axis of rotation, for 
torsionally locked installation on a drive shaft, cover plates on both 
sides of the hub disc which are torsionally locked to one another and held 
at a distance from one another, one of which supports the friction 
linings, windows in the hub disc and in the cover plates for the 
installation of spring actuators for relative torsional displacement when 
torque is applied, a radial guide between the one cover plate and the hub 
in the form of a guide element, which simultaneously represents an axial 
stop in relation to the hub, an external toothing pointing radially 
outward in the hub, with which the hub disc is engaged by means of an 
internal toothing, a basic friction device located on the side of the 
external toothing of the hub opposite the guide element with a friction 
ring which is oriented concentrically to the axis of rotation, and is in 
contact with the end surface of the external toothing running 
perpendicular to the axis of rotation and is subjected to the spring force 
exerted by the other cover plate, characterized by the fact that the 
friction ring 16, 17 has a base body 18, 19 from which at least two first 
axial projections 20 distributed over the circumference are engaged 
without clearance in those areas of the tooth spaces of the external 
toothing 6 of the hub 2 in the circumferential direction which are not 
occupied axially by the internal toothing 5 of the hub disc 4. 
Another feature of the invention resides broadly in the clutch disc, 
characterized by the fact that the contour of the first projections 20 is 
essentially the same as the contour of the toothing 6. 
Yet another feature of the invention resides broadly in the clutch disc, 
characterized by the fact that the first projections 20 preferably run 
conically in the axial direction, and in particular become smaller away 
from the base body 18, 19. 
Still another feature of the invention resides broadly in the clutch disc, 
characterized by the fact that there are second axial projections 21 which 
are distributed over the circumference, and which have a smaller dimension 
Y than that of the tooth spaces of the external toothing 6. 
Yet still another feature of the invention resides broadly in the clutch 
disc, characterized by the fact that the manufacturing tolerances of the 
second projections 21 can be larger, that is, the dimensions less precise, 
at least in the circumferential direction. 
Another feature of the invention resides broadly in the clutch disc, 
characterized by the fact that the friction ring 17, in circumferential 
areas outside the first axial projections 20 with its base body 19 is 
corrugated axially toward the corresponding cover plate 8--to generate an 
axial prestress. 
Still another feature of the invention resides broadly in the clutch disc, 
characterized by the fact that the base body 19, on the circumference, 
outside the projections 20, has corrugation crests 22, which run opposite 
to the projections 20 and have a flat surface 23. 
Yet still another feature of the invention resides broadly in the clutch 
disc, whereby there is a clearance in the circumferential direction 
between the internal toothing of the hub disc and the external toothing of 
the hub, and there are spring actuators between the hub disc and the hub 
for an idle spring device, characterized by the fact that on the external 
toothing 6 of the hub 2, on one side, the hub disc 26 is rigidly fastened, 
the guide element 13 of the cover plate 7 corresponding to the hub disc 26 
is in contact by means of an axially oriented leg 14 with the hub disc 26, 
there is an axially spring mounted friction ring 16 on the opposite side 
between the cover plate 8 and the end surface of the toothing 6, and the 
hub disc 4 is located between the friction ring 16 and the hub disc 26 of 
the idle spring device. 
The present invention preferably eliminates fluctuations in the torsional 
loading of the clutch and engine assembly by the rotating transmission, 
which may be present in the prior art. These fluctuations in loading by 
the transmission may have a disruptive effect upon the adjustment of the 
idle during tuning of the engine in sensitive vehicles. The change in the 
loading originating in the transmission, which change in loading is then 
transmitted to the clutch assembly, will, at least, cause intermittent 
loading of the engine by the transmission, making it difficult to adjust 
the idle in sensitive vehicles. 
Examples of friction clutches and friction clutch discs which may be 
utilized in accordance with the embodiments of the present invention may 
be found in the following United States Patents: U.S. Pat. No. 3,861,764, 
which issued to Adams on Jan. 21, 1975, entitled "Bearing Assembly and 
Bearing Bushing Therefor"; U.S. Pat. No. 4,433,771, which issued to Caray 
on Feb. 28, 1984, entitled "Torsion Damping Device for a Clutch Plate"; 
4,453,838, which issued to Loizeau on Jun. 12, 1984, entitled U.S. Pat. 
No. "Torsion Damping Assembly and Radially Deformable Bearing Therefor"; 
4,635,780, which issued to Wiggen on Jan. 13, 1987, entitled "Clutch Disc 
for a Motor Vehicle Friction Clutch"; U.S. Pat. No. 4,684,007, which 
issued to Maucher on Aug. 4, 1987, entitled "Clutch Plate"; 4,697,682, 
which issued to Alas et al. on Oct. 6, 1987, entitled "Torsional Damper 
Device"; U.S. Pat. No. 4,763,767, which issued to Lanzarini et al. on Aug. 
16, 1988, entitled "Torsional Damper Device"; and 4,890,712, which issued 
to Maucher et al. on Jan. 2, 1990, entitled "Torsional Vibration Damping 
Device for Clutch Plates". 
All, or substantially all, of the components and methods of the various 
embodiments may be used with at least one embodiment or all of the 
embodiments, if any, described herein. 
All of the patents, patent applications and publications recited herein, if 
any, are hereby incorporated by reference as if set forth in their 
entirety herein. 
The corresponding foreign patent publication applications, namely, Federal 
Republic of Germany Patent Application No. P 42 41 280.3, filed on Dec. 8, 
1992, having inventors Norbert Ament and Harold Raab, and DE-OS P 42 41 
280.3 and DE-PS P 42 41 280.3, as well as their published equivalents, and 
other equivalents or corresponding applications, if any, in corresponding 
cases in the Federal Republic of Germany and elsewhere, and the references 
cited in any of the documents cited herein, are hereby incorporated by 
reference as if set forth in their entirety herein. 
The details in the patents, patent applications and publications may be 
considered to be incorporable, at applicant's option, into the claims 
during prosecution as further limitations in the claims to patentably 
distinguish any amended claims from any applied prior art. 
The invention as described hereinabove in the context of the preferred 
embodiments is not to be taken as limited to all of the provided details 
thereof, since modifications and variations thereof may be made without 
departing from the spirit and scope of the invention.