Clutch operating apparatus

An apparatus which is used to operate a clutch in the power train between the prime mover and the transmission of a motor vehicle has a bearing which can be moved axially against the prongs of the clutch spring to change the state of the clutch between an engaged and a disengaged condition. In addition to being movable in response to the depression of a clutch pedal, the bearing is also movable by a compensating unit forming part of the clutch operating apparatus and serving to compensate for wear upon the friction linings of the clutch disc and, if necessary, upon the pressure plate and the counterpressure plate of the clutch. The means for moving the bearing in order to compensate for such wear includes two sets of complementary ramps or cams which can move the bearing toward the pressure plate in response to angular movement of an annular member which carries one set of the cams or ramps and which is biased by an energy storing element to turn in a direction necessary to move the bearing in order to compensate for wear, i.e., in addition to that movement of the bearing which is necessary to change the condition of the clutch.

BACKGROUND OF THE INVENTION 
The present invention relates to improvements in apparatus for operating 
clutches. More specifically, the invention relates to improvements in 
apparatus which can be utilized with advantage as a means for operating 
friction clutches of the type utilized in power trains between engines or 
other prime movers, and variable-speed transmissions in motor vehicles. 
A clutch of the type suitable to be operated by the apparatus of the 
present invention normally comprises operating means, such as a diaphragm 
spring, which changes its orientation and/or position during engagement 
and disengagement of the clutch. Conventional operating apparatus employ a 
carrier which is or which can be installed on the case of the transmission 
and mounts at least one support. The latter carries an actuator which is 
rotatable about and movable in the direction of the common axis of the 
pressure plate, counterpressure plate and housing of the clutch. The 
actuator serves to displace the operating means of the clutch by way of a 
bearing and the support prevents the bearing from leaving the position it 
assumes when the clutch is engaged. The means for moving the actuator 
relative to the support in the axial direction of the clutch includes a 
system of cams or ramps which cause the actuator to move axially of the 
clutch in response to rotation of the actuator relative to the support. 
Reference may be had, for example, to published French patent application 
No. A 2 658 763. 
A drawback of presently known clutch operating apparatus, including that 
disclosed in the aforementioned published French patent application, is 
that they are rather complex (because they comprise a large number of 
parts), prone to malfunction and expensive. Furthermore, the assembly of 
the parts is a highly complex and time consuming operation. 
Another drawback of heretofore known clutch operating apparatus is that, if 
the clutch is provided with a mechanism which is to compensate for wear 
upon the friction linings of the clutch disc and/or upon the friction 
surfaces of the pressure plate and counterpressure plate, the bearing or 
bearings of the operating apparatus are no longer capable of moving the 
operating means of the clutch to one and the same position relative the 
pressure plate and counterpressure plate as the wear upon the friction 
linings and certain other components of the clutch increases, i.e., in 
response to progressing axial shifting of the pressure plate toward the 
counterpressure plate and attendant change of orientation of the operating 
means of the clutch, such as the aforementioned clutch spring. The problem 
is particularly serious if the force-transmitting connection between the 
clutch pedal in a motor vehicle and the bearing of the clutch operating 
apparatus comprises a linkage or a bowden wire. The tolerances in the 
force transmitting connection are compounded by tolerances which develop 
in such connection as a result of progressing wear upon the friction 
linings of the clutch disc and the friction surfaces of neighboring parts. 
In other words, the play which develops between the clutch pedal and the 
bearing or bearings of the clutch operating apparatus due to progressing 
wear upon the friction linings is not compensated for by heretofore known 
clutch operating apparatus so that the clutch is not likely to be 
disengaged to the desired extent as soon as the wear upon the friction 
linings reaches a certain value. Thus, the distance which the bearing or 
bearings of the clutch operating apparatus should cover in response to 
repeated depression of the clutch pedal, in order to ensure that the 
positions of various parts of the clutch relative to each other do not 
change in response to repeated engagement and disengagement of the clutch, 
varies during the useful life of the clutch and the conventional operating 
apparatus therefor. In fact, the total play in the force-transmitting 
connection can rise to a value at which the aforementioned compensating 
mechanism is no longer capable of adequately compensating for wear upon 
the friction linings so that the engagement and/or disengagement of the 
friction clutch is no longer predictable. Thus, there exists an urgent 
need for clutch operating apparatus which are constructed and assembled in 
such a way that their operation is not affected by progressing wear upon 
certain components of the clutch and/or by progressing wear upon the 
constituents of the clutch operating apparatus. 
OBJECTS OF THE INVENTION 
An object of the invention is to provide a clutch operating apparatus whose 
operation is not affected by progressing wear upon the friction linings, 
the pressure and counterpressure plates and the clutch spring of a clutch, 
such as a friction clutch between the engine or another prime mover and 
the transmission of a motor vehicle. 
Another object of the invention is to provide a simple and compact clutch 
operating apparatus which can be installed in motor vehicles or other 
machines in a simple and time-saving manner. 
A further object of the invention is to provide an inexpensive clutch 
operating apparatus which comprises a relatively small number of simple 
parts. 
An additional object of the invention is to provide an apparatus which can 
be utilized to operate heretofore known clutches, such as friction 
clutches for use in motor vehicles. 
Still another object of the invention is to provide an apparatus which is 
capable of operating a clutch in a highly predictable manner during the 
entire useful life of the clutch. 
A further object of the invention is to provide an apparatus which can be 
utilized with advantage to operate clutches of the type disclosed in 
commonly owned German patent applications Nos. P 42 39 291.8, P 42 39 
689.6, P 42 43 667.6 and P 43 17 586.4 as well as in the corresponding 
United States patent applications. The disclosures of the aforementioned 
corresponding United States patent applications are incorporated herein by 
reference. 
Another object of the invention is to provide a clutch operating apparatus 
which is constructed and assembled in such a way that it can maintain the 
operating means of a clutch in an optimum position during engagement as 
well as during disengagement of the clutch irrespective of the extent of 
wear upon the parts of the improved apparatus. 
An additional object of the invention is to provide a clutch operating 
apparatus which ensures predictable and optimal positioning of those parts 
which must be displaced in order to change the condition of the clutch 
between a condition of engagement and a condition of disengagement. 
Still another object of the invention is to provide a novel and improved 
method of assembling the improved clutch operating apparatus. 
A further object of the invention is to provide novel and improved means 
for compensating for wear upon the constituents of the above-outlined 
clutch operating apparatus. 
Another object of the invention is to provide a novel and improved power 
train between the clutch pedal of a motor vehicle and the bearing or 
bearings which must be moved in order to engage or disengage a friction 
clutch between the prime mover and the transmission of the vehicle. 
An additional object of the invention is to provide a vehicle which 
embodies the above-outlined clutch operating apparatus. 
SUMMARY OF THE INVENTION 
The invention is embodied in an apparatus for operating a clutch 
(particularly a friction clutch in the power train between a prime mover, 
such as the engine of a motor vehicle, and a transmission) having 
operating means (e.g., a clutch spring, particularly a diaphragm spring) 
rotatable about a predetermined axis and movable in the direction of the 
axis between first and second positions in which the clutch is 
respectively engaged and disengaged. The operating means of the clutch is 
moved in the direction of the axis as a result of progressing wear upon at 
least one component of the clutch. The improved apparatus comprises: (1) a 
bearing (e.g., an antifriction bearing) including a rotary portion (e.g., 
one of the races of an antifriction bearing) which is movable in the 
direction of the axis to move the operating means from one to the other of 
the first and second positions, (2) a carrier (e.g., a hollow carrier 
mounted on the housing or case of the transmission in a motor vehicle), 
(3) at least one support mounted on the carrier, (4) an actuator mounted 
on the at least one support for rotation about the axis relative to the at 
least one support and for movement relative to the carrier in the 
direction of the axis to thus move the operating means of the clutch from 
one to the other of the first and second positions, (5) means for moving 
the actuator relative to the at least one support in the direction of the 
axis in response to rotation of the actuator relative to the at least one 
support, and (6) means for at least partially compensating for wear upon 
the at least one component of the clutch, including means for moving the 
bearing in the direction of the axis relative to the carrier. The 
compensating means can be installed between the carrier and the at least 
one support. The at least one support can be mounted in such a way that it 
is movable relative to the carrier in the direction of the axis. 
The apparatus can further comprise means for nonrotatably securing the at 
least one support to the carrier. 
The carrier can comprise a tubular portion and the at least one support can 
be constructed and mounted in such a way that it is movable relative to 
the tubular portion of the carrier in the direction of the axis. The at 
least one support can include a radially inner tubular portion. One of the 
two tubular portions is preferably surrounded by the other tubular portion 
and the tubular portion of the at least one support is preferably movable 
relative to the tubular portion of the carrier in the direction of the 
axis. 
The at least one support can be disposed between the actuator and the 
compensating means. 
The bearing can be mounted directly on the actuator and the means for 
moving the actuator relative to the at least one support can include at 
least one first cam (e.g., a ramp) on the actuator and at least one 
complementary second cam (e.g., a ramp) which is provided on the at least 
one support and cooperates with the at least one first cam to move the 
actuator relative to the at least one support in the direction of the axis 
in response to rotation of the actuator relative to the at least one 
support. The means for moving the actuator relative to the at least one 
support can further comprise rolling elements between the first and second 
cams. 
In accordance with a presently preferred embodiment, the compensating means 
of the clutch operating apparatus comprises ramps. The ramps can slope in 
the direction of the axis; such ramps can include at least one first set 
of ramps and at least one second set of ramps complementary to the ramps 
of the first set. The ramps of the at least one first set are turnable 
about the axis relative to the ramps of the at least one second set. The 
ramps of the at least one second set can be non-rotatably secured to 
(e.g., they can form part of) the carrier. 
The ramps of the at least one first set can be provided on a rotary annular 
member of the means for moving the bearing in the direction of the axis 
relative to the carrier, and such annular member can be mounted for rotary 
movement about the axis and relative to the carrier. Furthermore, the 
annular member can be mounted for movement relative to the carrier in the 
direction of the axis. The annular member can form part of a power train 
between the carrier and the at least one support, and the at least one 
support can be directly coupled to the annular member against movement in 
the direction of the axis. 
The means for moving the actuator relative to the at least one support can 
be disposed at a first radial distance from the axis and the compensating 
means can be disposed at a lesser second radial distance from such axis. 
Furthermore, the bearing can be disposed at a first distance from the 
carrier (as seen in the direction of the axis) and the compensating means 
can be disposed at a second distance from the carrier; the second distance 
can equal or at least approximate the first distance. 
The annular member of the means for moving the bearing in the direction of 
the axis relative to the carrier can be mounted in such a way that it at 
least partially surrounds a tubular portion of the at least one support. 
The compensating means can include at least one first set of ramps and at 
least one second set of ramps which are complementary to the ramps of the 
at least one first set. The ramps of the at least one first set or the 
ramps of the at least one second set are turnable about the axis relative 
to the ramps of the at least one second set or the ramps of the at least 
one first set and each ramp of the at least one first set has a first 
surface abutting a second surface on one of the ramps of the at least one 
second set. The first surfaces and the respective second surfaces are in 
self-locking engagement with each other and are inclined relative to a 
plane which is normal to the axis. The first and/or second surfaces can be 
inclined relative to the aforementioned plane through angles of between 
about 3.degree. and 15.degree., preferably between about 4.degree. and 
10.degree.. 
The ramps of the at least one first set or the at least one second set can 
be mounted for rotation about the axis relative to the complementary ramps 
of the at least one second set or the at least one first set, and each 
ramp can be mounted in such a way that it can slide relative to the 
complementary ramp. The compensating means embodying such ramps can 
further include resilient means for urging the at least one second set of 
ramps or the at least one first set of ramps in a direction to compensate 
for wear upon the at least one component of the clutch. The resilient 
means can comprise at least one coil spring surrounding at least a portion 
of the aforementioned annular member forming part of the means for moving 
the bearing in the direction of the axis relative to the carrier. 
The ramps of the at least one first set or the ramps of the at least one 
second set can form part of a power train between the ramps of the at 
least one second set or the ramps of the at least one first set and the 
bearing, and the resilient means is mounted and designed in such a way 
that it is operative to move the ramps of the at least one first set or 
the ramps of the at least one second set in the direction of the axis in 
order to move the operating means of the clutch in the direction of the 
axis by way of the bearing; this causes the bearing to move relative to 
the carrier in the direction of the axis to compensate for wear upon the 
at least one component of the clutch. 
The annular member of the means for moving the bearing in the direction of 
the axis relative to the carrier can be mounted for rotation relative to 
the at least one support about the axis, and the compensating means 
employing such annular member can further comprise means for limiting the 
extent of rotation of the annular member relative to the at least one 
support. 
The bearing can be installed in such a way that it is movable relative to 
the carrier in the direction of the axis through a first distance to 
thereby move the operating means of the clutch between the first and 
second positions, and the annular member of the means for moving the 
bearing in the direction of the axis relative to the carrier is then 
movable in the direction of the axis through a second distance which 
matches or at least approximates the first distance. The means for moving 
the actuator relative to the at least one support can include at least one 
first cam (e.g., a ramp) which is provided on the carrier or on the at 
least one support and at least one complementary second cam (e.g., a ramp) 
which is movable relative to the at least one first cam to thereby move 
the actuator and the bearing in response to rotation of the actuator 
relative to the at least one first cam. 
The at least one first cam can be provided on the at least one support and 
the at least one second cam can be provided on the annular member to move 
the annular member and the bearing in the direction of the axis relative 
to the at least one support in response to rotation of the annular member 
relative to the at least one support, and the cams can include or can 
carry means for limiting the extent of rotation of the annular member 
relative to the at least one support. The compensating means of such 
apparatus can further comprise at least one rolling element between the 
first and second cams, and the limiting means can comprise stops for the 
at least one rolling element; such stops can be provided at the end 
portions of the cams. 
The apparatus can further comprise means for limiting the extent of 
movability of the bearing in the direction of the axis relative to the 
carrier. Such means for limiting can include means for limiting the extent 
of rotation of the annular member of the means for moving the bearing in 
the direction of the axis relative to the at least one support or relative 
to the carrier. 
The apparatus can be constructed in such a way that the at least one 
support is movable relative to the carrier in the direction of the axis, 
and such apparatus can further comprise means for limiting the extent of 
movability of the at least one support relative to the carrier. Such means 
for limiting can comprise complementary detents provided on the at least 
one support and on the carrier, and the detents can be designed in such a 
way that they are engageable with each other by snap action. 
The apparatus can also comprise means for temporarily maintaining the 
bearing in a position corresponding to the first position of the operating 
means prior to initial movement of the operating means to the second 
position. Such means for maintaining can include means for holding the 
means for moving the bearing in a position which the bearing assumes in 
the absence of wear upon the at least one component of the clutch. The 
means for maintaining can be installed between the carrier and the annular 
member of the means for moving the bearing relative to the carrier. 
The apparatus can also comprise means for blocking the movement of the 
bearing by the moving means in a direction to compensate for wear upon the 
at least one component of the clutch prior to initial disengagement of the 
clutch. 
A clutch which is to be operated by the apparatus of the present invention 
can be constructed and assembled in such a way that it comprises a 
counterpressure plate which is rotatable about the axis, a pressure plate 
which has only limited freedom of axial movement relative to the 
counterpressure plate, operating means including at least one clutch 
spring (such as a diaphragm spring) which biases the pressure plate 
against a rotary clutch disc between the two plates in the engaged 
condition of the clutch, and friction linings constituting or forming part 
of the at least one component and being mounted on the clutch disc to be 
clamped between the friction surfaces of the pressure plate and the 
counterpressure plate in the engaged condition of the clutch. The pressure 
plate moves nearer to the counterpressure plate in response to progressing 
wear upon the friction surfaces of the two plates and/or upon the friction 
linings on the clutch disc, and the at least one clutch spring includes a 
portion (such portion can include a set of radially extending prongs or 
tongues forming part of a diaphragm spring) which is engaged by the 
bearing in the disengaged condition of the clutch. The apparatus for 
operating such clutch can further comprise means for displacing the clutch 
spring in the direction of the axis in response to progressing wear upon 
the friction surfaces and/or upon the friction linings so that the bias of 
the at least one clutch spring upon the pressure plate in the engaged 
condition of the clutch remains at least substantially unchanged 
regardless of the extent of wear upon the friction surfaces and/or upon 
the friction linings. 
A clutch of the above-outlined character can further comprise a housing 
which is rotatable with the counterpressure plate and the pressure plate, 
and a seat (e.g., a composite seat) provided on the housing to tiltably 
mount the at least one clutch spring. The latter then acts not unlike a 
two-armed lever having a first arm disposed radially inwardly or radially 
outwardly of the seat and engaging the pressure plate in the engaged 
condition of the clutch, and a second arm which is located radially 
outwardly or radially inwardly of the seat and is engaged by the bearing, 
at least in the disengaged condition of the clutch. The displacing means 
of the apparatus for operating such clutch can include means for biasing 
the at least one clutch spring against the seat, and the means for moving 
the bearing in the direction of the axis can include the aforementioned 
annular member which serves to bias the operating means with a force 
increasing in response to progressing wear upon the friction linings to 
thus overcome the force of the biasing means. The compensating means of 
such apparatus can further comprise means for moving the annular member in 
the direction of the axis toward the counterpressure plate to an extent 
which suffices to at least compensate for the extent of movement of the 
pressure plate nearer to the counterpressure plate as a result of wear 
upon the friction surfaces of the two plates and/or upon the friction 
linings of the clutch disc. 
The clutch which can be operated by the improved apparatus can include a 
counterpressure plate which is a composite flywheel including a first 
flywheel rotatable about the axis and adapted to be driven by the output 
element of a prime mover (such as a combustion engine in a motor vehicle), 
a second flywheel rotatable relative to and with the first flywheel and 
having a friction surface engageable by the friction linings of the clutch 
disc, and at least one damper which yieldably opposes rotation of the 
first and second flywheels relative to each other. The means for moving 
the actuator of the apparatus for operating such clutch can include means 
for shifting the actuator relative to the counterpressure plate in 
response to wear upon the friction surfaces of the two plates and/or upon 
the friction linings.

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIGS. 1, 2 and 3 show the details of a novel and improved apparatus 1 which 
is constructed and assembled to operate a friction clutch 3. The common 
axis of the apparatus 1 and clutch 3 is shown at X--X, and the apparatus 1 
is installed between the housing or case of a variable speed transmission 
2 and the clutch 3, as seen in the direction of the axis X--X. The clutch 
3 includes a composite flywheel 72 including a first flywheel 73 
connectable to the output element (e.g., a camshaft or a crankshaft) of a 
combustion engine or another prime mover in a motor vehicle), a second 
flywheel 61 which is rotatable with as well as relative to the first 
flywheel 73, and one or more dampers 75 disposed between the flywheels 73, 
61 and serving to yieldably oppose rotation of the two flywheels relative 
to each other. The clutch 3 which is shown in FIGS. 1 to 3 can be of the 
type disclosed, for example, in commonly owned U.S. Pat. No. 5,180,335 
granted Jan. 19, 1993 to Maucher et al. for "Torsion damping assembly for 
use with clutches in motor vehicles". The patent shows a prime mover, a 
connection between the output element of the prime mover and the first 
flywheel of a composite flywheel, a transmission, and a connection between 
another flywheel of the composite flywheel and the input element of the 
transmission. The disclosure of the patent to Maucher et al. is 
incorporated herein by reference. 
The clutch operating apparatus 1 comprises a carrier 4 which, in the 
embodiment of FIGS. 1 to 3, is fixedly connected to the case of the 
transmission 2 by bolts 5 or other suitable fasteners. The illustrated 
carrier 4 is made of a suitable plastic material, e.g., in an injection 
molding or other suitable machine, and includes a hollow frustoconical 
portion 7 adjacent the case of the transmission 2 and a tubular portion 8 
which is coaxial with the portion 7 and extends from the smaller-diameter 
end of the portion 7 toward the composite flywheel 72. The carrier 4 
spacedly surrounds the input shaft 6 of the transmission 2. The tubular 
portion 8 of the carrier 4 mounts a support 9 which serves to take up the 
forces necessary to disengage the clutch 3 and to transmit such forces to 
the carrier 4, i.e., to the case of the transmission 2. The radially inner 
portion 10 of the support 9 is a tube which surrounds and is movable 
axially of, as well as rotatable about, the axis X--X relative to the 
tubular portion 8 of the carrier 4. 
The apparatus 1 further comprises an annular actuator 11 which, in the 
embodiment of FIGS. 1 to 3, is made of a metallic sheet material and is 
mounted for axial movement relative to, as well as for rotation with 
respect to, the support 9. The means (12) for moving the actuator 11 
relative to the support 9 in the direction of the axis X--X comprises a 
first set of cams or ramps (hereinafter called cams) 13 on the actuator 11 
and a second set of complementary cams or ramps (hereinafter called cams) 
14 on the support 9. The moving means 12 further comprises rolling 
elements (e.g., spheres) 15 which are disposed between the cams 13 and the 
respective (complementary) cams 14. The cams 13, 14 extend in the 
circumferential direction of the annular actuator 11 and their confronting 
surfaces slope in the direction of the axis X--X from the carrier 4 toward 
the friction clutch 3. In the apparatus 1 of FIGS. 1 to 3, the cams 13 are 
of one piece with the actuator 11 and the cams 14 are of one piece with 
the support 9. The cams 13 can constitute suitably deformed portions of 
the actuator 11, and the cams 14 can constitute suitably deformed portions 
of the support 9. The actuator 11 is made of metallic sheet material, the 
same as the support 9, and the cams 13, 14 can be obtained by upsetting or 
otherwise displacing certain portions of the parts 11 and 9, respectively. 
However, it is equally possible to employ two separately produced 
ring-shaped members one of which is provided with the ramps 13 and the 
other of which is provided with the ramps 14. The one member is welded or 
otherwise affixed to the actuator 11, and the other member is welded or 
otherwise affixed to the support 9. 
The actuator 11 carries an antifriction ball bearing 16 which serves to 
actually disengage the clutch 3 by moving the operating means of the 
clutch in a direction to the left, as viewed in FIG. 1. The operating 
means includes the tips 19a of radially inwardly extending prongs 19 
forming part of the clutch spring 25 here shown as a diaphragm spring 
acting not unlike a two-armed lever. FIG. 1 shows the operating means 19a 
in a first end position (as seen in the direction of the axis X--X) in 
which the clutch 3 is engaged. The bearing 16 can move the operating means 
19a in a direction to the left, as viewed in FIG. 1, to a second end 
position in which the clutch 3 is disengaged because its clutch plate or 
clutch disc 28 is no longer clamped between the friction surface of the 
flywheel 61 and the friction surface of a pressure plate 41 having limited 
freedom of axial movement relative to but sharing all angular movements of 
the counterpressure plate constituted by the composite flywheel 72 of the 
clutch. 
The bearing 16 has limited freedom of axial movement relative to the 
actuator 11. In order to effect a relative axial movement between the 
bearing 16 and the actuator 11, it is necessary to overcome friction 
between the actuator and the outer race 17 of the bearing. The inner race 
18 of the bearing 16 can rotate with the clutch spring 25 because it 
includes a radially outwardly extending collar-shaped end portion 18a 
which bears against the operating means 19a. The connection between the 
outer race 17 and the actuator 11 is a force-locking connection which can 
be deactivated in response to the application of a predetermined force. 
FIG. 2 shows that the actuator 11 can change its angular position in 
response to a pull exerted by a flexible coupling 20 including a bowden 
wire or cord 22. The sheath 21 of the flexible coupling 20 has an end 
portion in contact with a triangular abutment 9a of the support 9. The 
wire 22 extends beyond the end portion of the sheath 21 and includes a 
hooked or otherwise configurated free end portion engaging a motion 
receiving arm 23 of the actuator 11. The non-illustrated end portion of 
the wire 22 is connected to the clutch pedal (not shown) of the motor 
vehicle embodying the clutch operating apparatus 1 of FIGS. 1 to 3. The 
triangular abutment 9a of the support 9 is provided with a tubular guide 
24 which serves as a stop for the adjacent end portion of the sheath 21 
and establishes a path for the wire 22 so that the free end portion of the 
wire 22 can be separably or non-separably secured to the motion receiving 
arm 23 of the actuator 11. The illustrated arm 23 is a separately produced 
part including a portion 31 which is welded or otherwise affixed to the 
actuator 11. 
The end portion 18a of the inner race 18 of the bearing 16 can constitute a 
circumferentially complete collar or it can be constituted by a set of 
radially outwardly extending tongues which cooperate with the operating 
means 19a of the prongs 19 forming part of the clutch spring 25 to 
disengage the clutch 3 by tilting the spring 25 relative to a seat 
assembly 60 at the inner side of the bottom wall or end wall forming part 
of the cover or housing 59 of the friction clutch 3. 
In accordance with a feature of the invention, the apparatus 1 further 
comprises a unit 26 which serves to compensate for progressing wear upon 
at least one component of the clutch 3, namely the friction linings 27 
disposed at both sides of resilient segments 63 forming part of the clutch 
disc 28. In addition to compensating for wear upon the friction linings 
27, the unit 26 can also compensate for wear upon the friction surface of 
the flywheel 61 and/or the friction surface of the pressure plate 41 
and/or the clutch spring 25. As a result of wear at least upon the 
friction linings 27 of the clutch disc 28, the operating means 19a of the 
clutch 3 move in a direction toward the composite flywheel 72, i.e., in 
the direction of the axis X--X and away from the carrier 4 on the case of 
the transmission 2. The unit 26 ensures that the cams 13, 14 can move the 
bearing 16 axially of the clutch 3 in a direction toward the composite 
flywheel 72 through the same distance irrespective of the wear upon the 
friction linings 27. Otherwise stated, the end portion 18a of the inner 
race 18 of the bearing 16 is always maintained in an optimum position 
relative to the operating means 19a regardless of the wear upon the 
friction linings 27 so that the axial distance covered by the actuator 11 
and the bearing 16 in response to depression of the clutch pedal (for the 
purpose of disengaging the clutch 3) remains at least substantially 
constant during the entire useful life of the clutch 3 and clutch 
operating apparatus 1. In other words, the moving means 12 need not change 
the extent of axial movement of the actuator 11 relative to the support 9 
in order to disengage the clutch 3 even if the friction surfaces of the 
flywheel 61 and pressure plate 41, the clutch spring 25 and/or the 
friction linings 27 have undergone extensive wear which progresses with 
the useful life span of the clutch 3. As a rule, progressing wear upon the 
friction linings 27 is the primary cause of axial shifting of the 
operating means 19a in the direction of the axis X--X and away from the 
carrier 4 of the clutch operating apparatus 1. 
As can be seen in FIG. 1, the support 9 and the actuator 11 are interfitted 
in the direction of the axis X--X. To this end, the actuator 11 comprises 
a substantially cupped portion 11a for the support 9. The latter has a 
substantially U-shaped cross-sectional outline. The leftmost portion of 
the support 9 is adjacent the radially extending part of the cupped 
portion 11 (as seen in the direction of the axis X--X). The cams 13 of the 
moving means 12 are provided on the radially outermost portion 29 of the 
actuator 11, and the cams 14 of the moving means 12 are provided on or at 
the radially outermost portion 30 of the support 9. The motion receiving 
portion or portions 23 of the actuator 11 are provided on the axially 
extending radially outermost portion 29. The aforementioned arm or arms 31 
of the motion receiving portion or portions 23 can be of one piece with 
the radially outermost portion 29 of the actuator 11. 
The aforementioned flexible coupling 20 including the bowden wire 22 and 
the sheath 21 is but one of several types of couplings which can transmit 
motion between a clutch pedal and the actuator 11. For example, the 
coupling 20 can be replaced by an electric, hydraulic or pneumatic 
servomotor (not shown) or any other suitable means for changing the 
angular position of the actuator 11 so that the latter is moved relative 
to the support 9 in the direction of the axis X--X and away from the 
carrier 4. If a servomotor is employed, it is preferably installed close 
to or even in the immediate proximity of the actuator 11, for example, on 
or at least close to the triangular portion 9a of the support 9. 
The compensating unit 26 is installed in the power train between the 
carrier 4 and the end portion 18a of the inner race 18 of the bearing 16 
and is disposed radially inwardly of the moving means 12 including the 
cams 13 and 14. More specifically, the illustrated compensating unit 26 is 
installed in the annular space between the tubular radially inner portion 
10 and the radially outer portion 30 of the support 9. The unit 26 
includes means for moving the bearing 16 in the direction of the axis X--X 
and away from the carrier 4, and such moving means includes an annular 
member 32 (see particularly FIGS. 3, 4 and 5). The annular member 32 is 
provided with two ring-shaped sets of ramps 33 and 34 with the ramps 34 
forming a ring which surrounds the ring formed by the ramps 33 (see 
particularly FIG. 4). The ramps 33 and 34 have elongated arcuate surfaces 
which slope in the direction of the axis X--X. The ramps 33 are offset 
relative to the ramps 34 in the circumferential direction of the annular 
member 32, for example, to such an extent that one half of each ramp 33 is 
disposed at one side and the other half of each ramp 33 is disposed at the 
other side of the highest point of the sloping surface of the respective 
ramp 34 and vice versa. This can be seen in FIG. 5. 
The annular member 32 which is shown in FIGS. 1, 3, 4 and 5 includes two 
ramps 33 and two ramps 34. In other words, each of these ramps extends 
along an arc of 180.degree.. However, it is equally within the purview of 
the invention to provide the annular member with three or more ramps 33 
and/or 34. The slope of the elongated surfaces of the ramps 33 and 34 
increases with the number of such ramps. 
The ramps 33, 34 are provided at one side or end face of the annular member 
32 and the other side or end face 35 of the member 32 is in direct contact 
with the adjacent portion of the support 9 (see particularly FIG. 3). The 
surface or end face 35 constitutes a frustum of a cone and abuts a 
complementary frustoconical surface 36 provided on the support 9 in the 
region of the extension 9a. The frustoconical surfaces 35, 36 cooperate to 
center the annular member 32 on the support 9. The annular member 32 
surrounds the tubular portion 10 of the support 9 which is centered by the 
carrier 4. 
The ramps 33, 34 of the annular member 32 extend in the direction of the 
axis X--X and away from the bearing 16. The member 32 is biased in a 
direction to turn about the axis X--X, namely in a direction such that it 
is caused to move in the direction of the axis X--X and away from the 
carrier 4. To this end, the ramps 33, 34 respectively cooperate with 
complementary ramps 37 and 38 (see particularly FIGS. 3, 6 and 7) on the 
adjacent end face of the stationary carrier 4. Thus, when the annular 
member 32 of the compensating unit 26 is free to turn about the axis X--X, 
it is caused to move axially and away from the carrier 4, i.e., toward the 
friction clutch 3. 
FIG. 6 shows that the ramps 38 which are complementary to and cooperate 
with the ramps 34 of the annular member 32 surround the ramps 37 which are 
complementary to and cooperate with the ramps 33 in response to rotation 
of the annular member 32 in such a direction that the member 32 is caused 
to move axially and away from the carrier 4. The ramps 37 are angularly 
offset relative to the ramps 38, the same as the aforediscussed ramps 33, 
34 of the annular member 32. The ramps 37 form a set of two arcuate ramps, 
and the ramps 38 also form a set of two arcuate ramps extending in the 
circumferential direction of the end portion of the carrier 4. The arcuate 
surfaces of the ramps 33 and 34 respectively slide along the arcuate 
surfaces of the ramps 37, 38 in response to rotation of the annular member 
32 to thus cause the member 32 to move toward the clutch 3 when it is 
caused to turn about the axis X--X. The arcuate surfaces of the ramps 33, 
34 and of the complementary ramps 37, 38 further serve as a means for 
accurately centering the member 32 relative to the carrier 4. The acute 
angles 40 between the sloping surfaces of the ramps 33, 34 on the annular 
member 32 and a plane which is normal to the axis X--X (see FIG. 5) match 
or at least closely approximate the angles 39 (FIG. 7) between the sloping 
surfaces of the ramps 37, 38 of the carrier 4 and a plane which is normal 
to the axis X--X. 
The annular member 32 can be made of a plastic material, the same as the 
carrier 4. Such material (e.g., a thermoplastic substance) is preferably 
resistant to heat and can be reinforced by filaments of carbon or other 
suitable material. This renders it possible to mass produce the annular 
member 32 in a suitable injection molding or other plastic processing 
machine, the same as the carrier 4. 
The ramps 37 and 38 can be formed or otherwise provided on an annular part 
(not specifically shown) which is produced in a separate step and is 
thereupon bonded or otherwise affixed to the end portion of the carrier 4 
adjacent the ramps 33, 34 of the annular member 32. The annular part can 
be a tight fit on the tubular portion 8 of the carrier 4 and can be 
additionally secured to the carrier so that it cannot turn with the 
annular member 32 when the latter is free to follow the spring bias and to 
turn about the common axis X--X of the friction clutch 3 and the clutch 
operating apparatus 1. 
The slopes of the arcuate surfaces of the ramps 33, 34 and 37, 38 and the 
lengths of such arcuate surfaces are selected with a view to ensure that 
the annular member 32 can turn relative to the carrier 4 through an angle 
which is sufficient to compensate for wear upon the friction surface of 
the flywheel 61 of the counterpressure plate constituted by the composite 
flywheel 72, upon the friction surface of the pressure plate 41 and/or 
upon the friction linings 27 during the entire useful life of the clutch 
3. Furthermore, the slopes and the dimensions of the ramps 33, 34 and 37, 
38 are or can be selected with a view to at least partially compensate for 
axial tolerances as a result of the making of the carrier 4 and/or the 
annular member 32 as well as for at least some tolerances which develop 
during assembly of the clutch operating apparatus 1. It is preferred to 
select the orientation and/or the dimensions of the ramps 33, 34 and 37, 
38 with a view to compensate for all anticipated tolerances of those 
constituents of the apparatus 1 which include the carrier 4, the end 
portion 18a of the inner race 18 of the antifriction bearing 16 and the 
parts between the carrier 4 and the end portion 18a. It has been found 
that, if the friction clutch 3 is installed in a passenger car, the ramps 
33, 34 and 37, 38 can compensate for wear upon the friction surface of the 
flywheel 61, upon the friction surface of the pressure plate 41, upon the 
friction linings 27 as well as for all machining and other tolerances 
(e.g., those developing during assembly of the apparatus 1) if the annular 
member 32 can turn relative to the carrier 4 through an angle which 
results in axial movement of the member 32 in a direction toward the 
friction clutch 3 through a distance of between about 4 mm and 12 mm. As a 
rule, or at least in many instances, only a fraction of such distance 
(normally between 1.3 mm and 2.5 mm) is necessary to compensate for wear 
upon the flywheel 61 and pressure plate 41 and/or the friction linings 27. 
Depending upon the number of cams 33, 34 and 37, 38, the angle through 
which the annular member 32 must be turned relative to the carrier 4 in 
order to achieve the aforementioned distances can be in the range of 
between about 30.degree. and 170.degree.. The angles 39 (FIG. 7) and 40 
(FIG. 5) can be in the range of between 3.degree. and 15.degree., 
preferably between about 5.degree. and 9.degree.. The angle 39 can vary in 
the radial direction of the carrier 4, and the angle 40 can vary in the 
radial direction of the annular member 32; this ensures that each 
increment of angular movement of the ramps 33, 34 on the annular member 32 
relative to the ramps 37, 38 of the carrier 4 results in identical axial 
displacements of the member 32 in the direction of the axis X--X and 
toward the clutch 3 within the entire range of axial mobility of the 
member 32 with reference to the carrier 4. This necessitates a gradual 
reduction of the angle 39 in a direction from the axis X--X toward the 
periphery of that portion of the carrier 4 which supports the ramps 37, 38 
and a gradual reduction of the angle 40 in a direction from the axis X--X 
toward the periphery of the annular member 32. 
The means for biasing the annular member 32 in a direction to cause the 
ramps 33, 34 to slide relative to the respective complementary ramps 37, 
38 includes at least one resilient element. FIGS. 1 and 3 show a coil 
spring 43 having convolutions surrounding the annular member 32 and being 
installed in stressed condition so that they always tend to turn the 
member 32 relative to the carrier 4 for the purpose of moving the member 
32 in the direction of the axis X--X and toward the friction clutch 3. To 
this end, the spring 43 reacts against the support 9 and bears upon the 
member 32. As can be seen in FIG. 3, the right-hand end convolution 44 of 
the coil spring 43 is affixed to the annular member 32 and the left-hand 
end convolution 45 of the spring 43 is non-rotatably connected to the 
support 9. The intermediate convolutions 46 between the end convolutions 
44 and 45 of the coil spring are stressed so that, when the annular member 
32 is free to turn relative to the carrier 4, they cause the member 32 to 
change its angular position so that the ramps 33, 34 slide along the 
adjacent ramps 37, 38 and cause the annular member 32 and the support 9 to 
move away from the transmission 2. The support 9 is movable axially of but 
cannot turn relative to the carrier 4. The movements of the annular member 
32 in a direction away from the transmission 2 are shared by the support 
9, by the actuator 11, by the rolling elements 15 and by the bearing 16. 
These parts can be said to form part of a module A which is movable 
axially of the friction clutch 3 relative to a fixed module B including 
the carrier 4. Axial mobility of the module A ensures that the end portion 
18a of the inner race 18 of the bearing 16 abuts the clutch operating 
means including the tips 19a of the prongs 19 forming part of the clutch 
spring 25. The end portion 18a bears upon the tips 19a with a 
predetermined force which ensures the establishment of a desirable bearing 
stress, e.g., a stress in the range of between approximately 10N and 70N. 
The compensating unit 26 exhibits the additional advantage that it does not 
turn about the axis X--X, i.e., the operation of its constituents is not 
affected by centrifugal force when the housing 59, the flywheel 61, the 
pressure plate 41 and the clutch spring 25 are rotated relative to the 
carrier 4 and support 9. 
FIGS. 2 and 6 show that the peripheral surface of the tubular portion 8 of 
the carrier 4 is provided with axially parallel projections 47 which are 
received in axially parallel internal recesses or grooves 48 of the 
tubular portion 10 forming part of the support 9. The projections 47 and 
the grooves 48 constitute male and female detents which confine the 
support 9 to axial movements relative to the carrier 4. 
The free end 49 (FIG. 3) of the tubular portion 8 of the carrier 4 can be 
configurated in such a way that it defines at least two but preferably 
more protuberances or similar formations 50 which must be displaced when 
the tubular portion 10 of the support 9 is slipped onto the tubular 
portion 8. In other words, the carrier 4 and the support 9 can be 
assembled in response to the application of a certain force which should 
suffice to displace the protuberances 50 so that the tubular portion 10 
can be moved toward the frustoconical portion 7 of the carrier 4. This 
ensures that, once the tubular portion 10 is slipped onto the tubular 
portion 8, the support 9 cannot be accidentally separated from the carrier 
4. At least the tubular portion 8 of the carrier 4 preferably exhibits at 
least some elasticity which must suffice to permit forcible assembly of 
the tubular portions 8 and 10 in a manner as shown in FIGS. 1 and 3, i.e., 
in such a way that the tubular portion 10 surrounds the tubular portion 8 
and is located to the right of the protuberances 50. 
Due to the provision of the wear compensating unit 26, the moving means 12 
including the cams 13, 14 and the rolling elements 15 is called upon only 
in order to disengage the clutch 3, i.e., to ensure that the friction 
linings 27 of the clutch disc 28 are no longer clamped between the 
friction surfaces of the flywheel 61 and the pressure plate 41 so that the 
composite flywheel 72 can turn relative to the clutch disc 28 and the 
input shaft 6 forming part of the transmission 2 and being non-rotatably 
coupled to the hub of the clutch disc 28. In other words, the moving means 
12 is called upon to move the bearing 16 and hence the operating means 19a 
of the clutch 3 only through a distance which is necessary to tilt the 
clutch spring 25 relative to the seat assembly 60 so that the 
circumferentially complete radially outer portion 25a of the clutch spring 
25 is moved toward the inner side of the bottom wall of the housing or 
cover 59 of the clutch 3. This enables the customary leaf springs 62 to 
move the pressure plate 41 axially and away from the flywheel 61. The leaf 
springs 62 couple the pressure plate 41 to the housing 59 and tend to move 
the pressure plate 41 axially and away from the flywheel 61. 
The apparatus 1 further comprises means for limiting the extent of 
movability of the actuator 11 and bearing 16 in the direction of the axis 
X--X in order to disengage the clutch 3. The limiting means includes stops 
13a, 14a (FIG. 2) on the end portions of the sloping surfaces of the ramps 
13 and 14; such stops are engaged by the respective rolling elements 15 in 
response to a predetermined angular displacement of the actuator 11 and 
bearing 16 relative to the support 9. Once the rolling elements 15 are 
confined by the respective pairs of stops 13a and 14a, the actuator 11 
cannot continue to turn relative to the support 9 in a direction to cause 
the cams 13 and 14 to continue to move the bearing 16 axially and away 
from the carrier 4. FIG. 2 shows the actuator 11 in the fully retracted 
position in which the clutch 3 is disengaged and the rolling elements 15 
cooperate with the corresponding stops 13a, 14a to prevent an additional 
axial movement of the bearing 16 in a direction away from the composite 
flywheel 72. The rolling elements 15 then cooperate with the respective 
stops 13a, 14a to establish a form-locking connection between the actuator 
11 and the support 9. Such form-locking connection is established when the 
actuator 11 assumes the end position which is shown in FIG. 2 (the clutch 
3 is then disengaged) as well as when the actuator 11 assumes its fully 
retracted position in which the clutch 3 is engaged because the clutch 
spring 25 is free to bias the pressure plate 41 against the friction 
linings 27 so that the friction linings are clamped between the friction 
surfaces of the pressure plate 41 and the flywheel 61. 
The rolling elements 15 are confined between the neighboring stops 13a, 14a 
in the engaged as well as in the disengaged condition of the friction 
clutch 3. 
The cams 13, 14 of the moving means 12 are preferably provided on the 
actuator 11 and the support 9 in such a way that the parts 9, 11 are 
coupled to each other upon completion of axial movement of the actuator 11 
relative to the support 9 to the position which is shown in FIG. 1 or 3. 
To this end, the sloping surfaces of the cams 13 and 14 can be provided 
with slight undercuts for the rolling elements 15 and the rolling elements 
enter such undercuts upon completion of their introduction between the 
neighboring cams 13 and 14. Insertion of the rolling elements 15 between 
the sloping surfaces of the respective cams 13, 14 preferably necessitates 
minor elastic deformation of the support 9 and/or actuator 11. The rolling 
elements 15 are inserted between the respective cams 13, 14 by moving in 
or close to the direction of the axis X--X. The necessary elastic 
deformation of the support 9 and/or actuator 11 will take place as a 
result of the application of a certain axially oriented force during 
slipping of the actuator 11 onto the support 9 until the actuator assumes 
the axial position which is shown in FIG. 3. 
The compensating unit 26 is preferably provided with means for limiting the 
extent of axial movability of the support 9 relative to the carrier 4. 
Such limiting means can be provided between the annular member 32 and the 
carrier 4 and can comprise stops which limit the extent to which the 
member 32 can turn relative to the carrier 4. 
When the friction clutch 3 is new, i.e., when the wear upon the friction 
surfaces of the flywheel 61 and of the pressure plate 41 and/or upon the 
friction linings 27 of the clutch disc 28 is nil or negligible, the ramps 
33, 34 engage the complementary ramps 37, 38 in such a way that the 
combined axial length of the four sets of ramps is at a minimum. In other 
words, the annular member 32 is held in a fully retracted position 
relative to the carrier 4. The bias of the coil spring 43 then assumes a 
maximum value, i.e., the intermediate convolutions 46 of the spring 43 are 
stressed to a maximum extent. 
The aforementioned module A includes the support 9, the actuator 11, the 
rolling elements 15, the bearing 16, the annular member 32 and the coil 
spring 43. The spring 43 is maintained in the stressed condition during 
assembly of the module A with the module B including the carrier 4. This 
means that the wear compensating unit 26 is ready for use as soon as the 
assembly of the modules A and B is completed. It is preferred to provide 
the apparatus with means 51 (FIG. 3) for temporarily maintaining the 
bearing 16 in a position corresponding to the first position of the 
operating means 19a prior to initial movement of the operating means 19a 
to the second position in which the clutch 3 is disengaged. The 
maintaining means 51 can be designed in such a way that the end portion 
18a of the inner race 18 of the bearing 16 is actually out of contact with 
the operating means 19a in the first position of the bearing. Such 
clearance between the parts 18a and 19a is eliminated in automatic 
response to the initial disengagement of the clutch 3, i.e., in automatic 
response to release of the compensating unit 26 so that the latter can 
perform its function of compensating (when necessary) for wear upon the 
friction linings 27 and one or more additional components of the clutch. 
The initial disengagement of the clutch 3 preferably takes place when the 
flywheel 73 of the composite flywheel 72 (i.e., of the counterpressure 
plate of the clutch 3) is not driven by an engine or another prime mover. 
Alternatively, the initial disengagement of the clutch 3 will preferably 
take place while the transmission 2 is in neutral. The reason is that the 
initial actuation does not always involve full disengagement of the 
clutch. Such initial disengagement is preferably carried out in the plant 
in which the apparatus 1 and the friction clutch 3 are made or in a plant 
(e.g., in an automobile making factory) in which the apparatus 1 and the 
clutch 3 are installed for actual use. 
The maintaining means 51 in the clutch operating apparatus of FIGS. 1 to 7 
comprises holding means in the form of lugs 52 carried by the annular 
member 32. The illustrated lugs 52 are of one piece with the member 32 
(FIG. 4). At least the radially inner portions 53 of the lugs 52 are 
configurated in such a way that the lugs can be pivoted relative to the 
annular main portion of the member 32 in radial planes including the axis 
X--X. In other words, the radially inner portions 53 can be said to 
constitute hinges which enable the lugs 52 to pivot relative to the 
adjacent part of the annular main portion of the member 32. Alternatively, 
the entire lugs or holding means 52 can be made of a material which 
renders it possible to flex the lugs relative to the main portion of the 
member 32. Though FIG. 4 shows that the annular member 32 is provided with 
only two lugs 52 which are disposed diametrically opposite each other, it 
is possible to employ three or more lugs which are or which can be 
equidistant from each other in the circumferential direction of the member 
32. The radially outer portions 54 of the lugs 52 abut stops 55 which are 
provided on (and can be of one piece with) the actuator 11. The stops 55 
form part of tongues 56 which (in the apparatus of FIGS. 1 to 7) are of 
one piece with the actuator 11 and have radially inwardly bent free end 
portions 57 (FIG. 3). The end portions 57 constitute abutments or stops 
for the radially outer portions 54 of the neighboring lugs 52. 
The resistance of the lugs 52 to buckling and flexing is selected in such a 
way that the lugs can readily withstand the bias of the coil spring 43 in 
the axial and circumferential directions of the annular member 32 and 
actuator 11. At the very least, the lugs 52 can withstand such bias with a 
minimum of deformation. 
The maintaining means 51 should be designed in such a way that it can 
transmit a torque exceeding that of the fully stressed coil spring 43. To 
this end, it is desirable to provide an additional (force-locking or 
form-locking) connection which acts in the circumferential direction of 
the annular member 32. When the clutch 3 is disengaged for the first time, 
the actuator 11 is turned about the axis X--X relative to the annular 
member 32 whereby the stops 55 release the adjacent lugs 52, i.e., the 
wear compensating unit 26 is rendered operative and can perform is 
intended function as the wear upon the friction linings 27 progresses. The 
lugs 52 then assume the positions 52a which are shown in FIG. 3 by 
dot-dash lines, i.e., they are caused to move their end portions 54 
radially inwardly toward the axis X--X. 
In assembling the module A of the clutch operating apparatus 1, the coil 
spring 43 is coupled to the annular member 32 and to the support 9. To 
this end, the end convolutions of the spring 43 can be provided with hooks 
or analogous configurations to facilitate their attachment to the parts 9 
and 32. The member 32 is thereupon turned relative to the support 9 and/or 
vice versa in order to ensure that the spring 43 stores a sufficient 
amount of energy. The aforementioned maintaining means 51 is thereupon 
actuated to ensure that the member 32 and the support 9 are held in 
angular positions in which the coil spring 43 remains stressed. The module 
A is thereafter assembled with the carrier 4 of the module B in such 
angular position that the ramps 33, 34 of the member 32 properly engage 
the complementary ramps 37, 38 of the carrier 4. The wear compensating 
unit 26 is then ready for use as soon as the initial displacement of the 
bearing 16 in a direction to disengage the clutch 3 is completed. 
When the wear upon one or more components (particularly the friction 
linings 27) of the friction clutch 3 has progressed to a certain extent, 
the unit 26 compensates for such wear by causing the entire module A to 
move axially toward the composite flywheel 72. Such movement is shared by 
that end portion of the bowden wire 22 which is coupled to the motion 
receiving arm 23 of the actuator 11 as well as by that end portion of the 
sheath 21 which abuts the tubular guide 24 on the abutment 9a of the 
support 9. The bowden wire 22 and its sheath 21 are preferably mounted in 
such a way that they do not generate any forces, or any appreciable 
forces, which would interfere with required movements of the support 9 and 
actuator 11 relative to each other. In other words, when not actuated, the 
flexible coupling 20 should not transmit any appreciable forces or it 
should transmit no forces at all. 
As shown in FIGS. 1 and 3, the motion receiving portion 23 of the actuator 
11 and the tubular guide 24 on the abutment 9a of the support 9 are offset 
relative to each other in the axial direction through a distance 58 
(referenced in FIG. 1 only) when the apparatus 1 does not maintain the 
clutch operating means 19a in a position corresponding to the disengaged 
condition of the clutch 3. The distance 58 is preferably reduced to zero 
or at least close to zero when the disengaging force acting upon the 
operating means 19a of the clutch 3 reaches a maximum value. 
It is advisable to design the sloping arcuate surfaces of the cams 13 and 
14 in such a way that their angle of slope varies in the circumferential 
direction of the actuator 11 and support 9 in order to ensure that the 
progress of the actuating force which is necessary to turn the actuator 11 
relative to the support 9 follows a preselected pattern, depending on the 
circumstances under which the clutch 3 and the apparatus 1 are being put 
to use. For example, it is desirable under certain circumstances to select 
the configuration of the sloping surfaces of the cams 13, 14 in such a way 
that the magnitude of the force which is being transmitted by the flexible 
coupling 20 or an equivalent of such coupling varies during that 
longitudinal movement of the bowden wire 22 which is necessary to 
disengage the clutch 3. This renders it possible to ensure that the 
magnitude of the disengaging force which is furnished by the coupling 20 
and the apparatus 1 is at least substantially constant. Such constancy of 
the disengaging force can be achieved by properly relating the 
transmission characteristic of the means 12 for moving the actuator 11 
relative to the support 9 to the progress of force which is being applied 
to the operating means 19a during disengagement of the clutch 3. Thus, if 
the magnitude of the disengaging force being applied to the operating 
means 19a increases, the transmission ratio of the moving means 12 
increases to thus reduce the magnitude of the force which must be 
furnished by the flexible coupling 20 or its equivalent. 
The sloping surfaces of the cams 13 and 14 can be concave, convex or partly 
concave and partly convex, either all the way or in part. 
FIG. 1 shows that the radius of the bearing 16 matches or at least 
approximates the radius of the wear compensating unit 26. Thus, the radial 
distance of the annular member 32 from the axis X--X can match or at least 
approximate the radial distance of the outer race 17 of the bearing 16 
from such axis. 
The support 9 and the actuator 11 can be made of metallic sheet material 
which is hardened, either entirely or at least in the regions of the 
respective cams 14 and 13. However, it is equally possible to make the 
support 9 and/or the actuator 11 of a suitable plastic material, for 
example, when the disengagement of the clutch necessitates the exertion of 
a relatively small force. This will be described in greater detail 
hereinafter. If at least one of the parts 9, 11 is made of a plastic 
material, it is or it can be desirable to embed suitably shaped metallic 
reinforcing parts (such as tracks, rails or the like) into the part 9 
and/or 11 at the respective cams 14 and/or 13. Such reinforcing parts can 
be hardened prior to being embedded in the plastic material. 
Those surfaces of the ramps 33, 34 which come into contact with the 
respective complementary ramps 37, 38 and those surfaces of the ramps 37, 
38 which come into contact with the respective complementary ramps 33, 34 
are or can be configurated, finished and/or otherwise treated in such a 
way that the ramps 33, 34 of the annular member 32 can automatically slide 
along the complementary ramps 37, 38 in a direction to move the member 32 
axially and away from the carrier 4 but that the connections between the 
ramps 33, 34 and 37, 38 are self-locking against movement in the opposite 
direction, i.e., that the ramps 33, 34 and 37, 38 establish a form-locking 
connection between the member 32 and the carrier 4 against angular 
movement of the member 32 in a direction to move it nearer to the 
transmission 2. For example, the arcuate sloping surfaces of the ramps 33, 
34 and/or 37, 38 can be roughened or otherwise finished (e.g., by the 
provision of rasters or other configurations) which ensure that the member 
32 cannot turn in a direction to move it nearer to the transmission 2 even 
if the member 32 and/or the carrier 4 is caused to perform vibratory, 
oscillatory and/or other stray movements which would tend to temporarily 
interrupt direct and full contact between the confronting surfaces of the 
ramps 33, 34 and the respective complementary ramps 37, 38. 
The improved apparatus 1 is particularly suitable for use as a means for 
engaging and disengaging a friction clutch of the type shown in FIG. 1, 
namely a clutch wherein the operating means including the tips 19a of 
prongs 19 is caused to move in the direction of the axis X--X and toward 
the counterpressure plate including the composite flywheel 72 to thus 
compensate for wear upon one or more components (particularly the friction 
linings) of the clutch. In other words, as the wear upon one or more 
components of the clutch progresses, the operating means including the 
tips 19a of the prongs 19 is moved in the same direction as the pressure 
plate 41. This ensures that the inclination of the prongs 19 relative to a 
plane which is normal to the axis X--X remains at least substantially 
unchanged irrespective of the extent of wear upon the friction surfaces of 
the flywheel 61 and pressure plate 41 and/or upon the friction linings 27. 
The friction clutch 3 which is shown in FIG. 1 is similar to those 
described and shown in the commonly owned German patent applications Nos. 
P 42 39 291.8, P 42 39 289.6, P 42 43 567.6 and P 43 17 586.4 and in the 
corresponding U.S. patent applications. The disclosures of such U.S. 
patent applications are incorporated herein by reference. 
The purpose of the resilient segments 63 between the two sets of friction 
linings is to ensure that the engagement of the friction clutch 3 involves 
a gradual increase of the torque which is being transmitted from the 
flywheel 61 and pressure plate 41 to the input shaft 6 of the transmission 
2. Thus, when the circumferentially complete radially outer main portion 
25a of the clutch spring 25 is free to bias the pressure plate 41 toward 
the counterpressure plate including the flywheel 61, the resilient 
segments 63 are caused to store energy during a certain initial stage of 
movement of the pressure plate 41 away from the bottom end wall 59a of the 
clutch housing 59. The next-following stage of movement of the pressure 
plate 41 is terminated when the combined axial length of the segments 63 
and the two sets of friction linings 27 is reduced to a minimum so that 
the clutch disc 28 and the input shaft 6 begin to rotate at the exact 
speed of the flywheel 61. Stated otherwise, the resilient segments 63 bias 
the two sets of friction linings 27 apart when the clutch 3 is disengaged 
and permit a gradual movement of the two sets of friction linings toward 
each other during engagement or reengagement of the clutch. 
It is equally within the purview of the invention to replace the 
illustrated clutch disc 28 with a clutch disc which does not employ 
resilient segments and/or with a clutch disc which employs one or more 
dampers between the friction linings and the hub of the clutch disc. Such 
clutch discs are described and shown in commonly owned U.S. Pat. No. 
5,161,660 (granted Nov. 10, 1992 to Huber for "Clutch plate with plural 
dampers") the disclosure of which is incorporated herein by reference. 
The clutch spring 25 is a diaphragm spring which is mounted on the radially 
extending end wall 59a of the housing 59 in such a way that it acts not 
unlike a two-armed lever including a radially outer arm (portion 25a) 
which can bias the pressure plate 41 and a radially inner arm (prongs 19 
and their tips 19a) which can be shifted in the direction of the axis X--X 
by the end portion 18a of the inner race 18 of the bearing 16. 
The seat assembly 60 for the clutch spring 25 includes a first seat 64 
engaging that side of the clutch spring which faces the pressure plate 41 
and a second seat 65 between the clutch spring and the bottom wall 59a of 
the housing 59. The seat 64 is biased against the clutch spring 25 by a 
diaphragm spring 66 having a radially outer portion 67 reacting against 
the housing 59. In the clutch 3 which is shown in FIG. 1, the seat 64 is 
constituted by a set of tongues which are of one piece with the diaphragm 
spring 66. The diaphragm spring 66 is installed in stressed condition so 
that its tongues which constitute the seat 64 are biased against the 
clutch spring 25 with a certain force which ensures that the opposite side 
of the spring 25 is maintained in contact with the seat 65. 
The diaphragm spring 66 constitutes a sensor of a displacing unit which 
serves to shift the clutch spring 25 in the direction of the axis X--X 
away from the bottom wall 59a of the housing 59 and toward the 
counterpressure plate including the flywheel 61 in order to compensate for 
wear upon the friction surfaces of the flywheel 61 and pressure plate 41 
and/or upon the friction linings 27 of the clutch disc 28. The 
construction and mounting of the diaphragm spring or sensor 66 are such 
that it biases the seat 64 against the adjacent side of the clutch spring 
25 with an at least substantially constant force during a predetermined 
stage of axial movement of the seat 65 and the adjacent part of the main 
portion 25a of the clutch spring 25 toward the flywheel 61. Stated 
otherwise, the force-to-distance characteristic of the diaphragm spring 66 
can be represented by a substantially straight curve. The diaphragm spring 
66 opposes and at least substantially counteracts the force which is being 
applied to the tips 19a of the prongs 19 of the clutch spring 25 during 
disengagement of the clutch 3. Thus, the bias of the diaphragm spring 66 
suffices to balance the maximum force which the end portion 18a of the 
inner race 18 of the bearing 16 applies to the operating means 19a during 
disengagement of the clutch 3. 
The displacing unit 68 which includes the diaphragm spring 66 is mounted on 
the rear wall 59a of the housing 59 and serves to automatically shift or 
displace the seat 65 of the seat assembly 60 in a direction toward the 
pressure plate 41 in order to compensate for wear upon the friction 
surfaces of the pressure plate 41 and flywheel 61 and/or upon the friction 
linings 27 and to thus ensure that the bias of the clutch spring 25 upon 
the pressure plate 41 remains unchanged in the engaged condition of the 
clutch regardless of the extent of wear upon the components 41, 61, 27 or 
at least the component 27 of the clutch. The unit 68 ensures that no 
clearance develops between the seat 65 and the wall 59a of the clutch 
housing 59 and/or between the seat 65 and the adjacent side of the main 
portion 25a of the clutch spring 25. 
In addition to the diaphragm spring 66, the displacing unit 68 comprises a 
spring-biased adjusting element 69 in the form of a ring having an annulus 
of ramps 70 with surfaces extending in the circumferential direction and 
sloping in the direction of the axis X--X. The ramps 70 confront the 
bottom wall 59a of the housing 59 and cooperate with complementary ramps 
71 on the bottom wall 59a to ensure that the seat 65 (which is carried by 
the element 69) is moved in the direction of the axis X--X toward the 
pressure plate 41 when the element 69 and its ramps 70 are caused to turn 
relative to the housing 59. The means for biasing the element 69 in a 
direction to cause its ramps 70 to slide relative to the respective ramps 
71 ensures that the extent of axial movement of that portion of the clutch 
spring 25 which is clamped between the seats 64 and 65 toward the pressure 
plate 41 matches the extent of axial movement of the element 69 due to 
angular movement of the element 69 relative to the bottom wall 59a of the 
housing 59, i.e., the extent of axial movement of the element 69 away from 
the bottom wall 59a. 
Those surfaces of the ramps 70, 71 which contact each other are or can be 
configurated and/or treated in such a way that they do not oppose angular 
movements of the element 69 in a direction to move it axially of and away 
from the bottom wall 59a but that they prevent any angular movements of 
the element 69 in the opposite direction. This can be achieved by 
providing the sloping surfaces of the ramps 70 and/or 71 with small 
projections, with otherwise roughened portions, with rasters and/or 
combinations of such expedients. Satisfactory results can be obtained by 
shot peening or sand blasting the sloping surfaces of the ramps 70 and/or 
71. Even more satisfactory results can be achieved by peening or blasting 
with coarse particles having a plurality of sharp edges, e.g., with 
particles of quartz sand. Such coarse particles ensure rapid and 
pronounced coarsening of the sloping surfaces even if the blasting or 
peening operation is completed within a short interval of time and even if 
the intensity of peening or blasting is relatively low. This contributes 
to lower cost of the coarsening operation and reduces the likelihood of 
undesirable deformation of the parts (69 and 59a) which carry the ramps 70 
and 71. Peening with spherical particles is also possible even though it 
must involve the propulsion of spherical particles against the sloping 
surfaces of the ramps 70 and/or 71 with a highly pronounced intensity in 
order to ensure that the ramps 71 can successfully oppose rotation of the 
element 69 and its ramps 70 in a direction to move the element 69 closer 
to the bottom wall 59a of the clutch housing 59. This might even involve 
some undesirable or unnecessary deformation of the ramps 70 and/or 71. 
Therefore, blasting with coarse particles of quartz or the like is 
preferred at this time. 
The aforediscussed treatment of sloping surfaces on ramps or cams can be 
resorted to with equal or similar advantage in connection with the 
treatment of the sloping surfaces of the cams 13, 14, of the ramps 33, 34 
and/or of the ramps 37, 38. Furthermore, it is not always necessary to 
roughen the sloping surfaces of cams or ramps or to roughen or similarly 
treat only the sloping surfaces of ramps or cams which cooperate with each 
other in a manner as described and shown in connection with the cams 13, 
14 of the moving means 12, with the ramps 33, 34 and 37, 38 of the 
compensating unit 26, and/or with the ramps 70, 71 of the displacing unit 
68. All that counts is to ensure that the cams 13 can turn relative to the 
corresponding cams 14 only in a single direction, that the ramps 33, 34 
can turn relative to the ramps 37, 38 in a single direction and that the 
ramps 70 can turn relative to the ramps 71 in a single direction. By way 
of example, the sloping surfaces of the ramps 33, 34 and/or 37, 38 need 
not be roughened if the frustoconical surface 35 of the annular member 32 
and/or the complementary frustoconical surface 36 of the support 9 is 
treated in such a way that the member 32 can be turned relative to the 
support only in a direction to move it further away from the transmission 
2. In other words, any and all angular movement of the cams 13 and/or 
ramps 33, 34 and/or ramps 70 in a wrong direction can be prevented by 
suitable treatment of the sloping surfaces of such cams and/or ramps 
and/or by suitable treatment of the parts (such as the actuator 11, the 
support 9 and a part of the housing 59 other than the bottom wall 59a) 
which are in direct surface-to-surface contact with the actuator 11, 
annular member 32 and element 69. 
As a rule, the tendency of the cams 13, of the ramps 33, 34 and/or of the 
ramps 70 to turn in the wrong direction would be attributable to minute 
vibratory, oscillatory or other stray movements of parts which should be 
limited to angular movement in a single direction. In many instances the 
stray movements (which can take place at a high frequency) are caused 
primarily by axial vibrations and/or flexing of the input element (e.g., 
the camshaft or the crankshaft of an engine in a motor vehicle) which 
drives the flywheel 73 of the composite flywheel 72. The stray movements 
are transmitted to the flywheels 61 and 73 so that the counterpressure 
plate of the clutch performs axial and/or pendulum or similar movements 
which are transmitted to other parts of the clutch 3 as well as to the 
clutch operating apparatus 1. 
All additional details of presently preferred embodiments of the displacing 
unit 68 which can be utilized in the friction clutch 3 or an analogous 
clutch are fully disclosed in the aforementioned commonly owned German 
patent applications and in the corresponding U.S. patent applications. 
FIG. 1 further shows an antifriction bearing 74 between the flywheels 61, 
73 of the composite flywheel or counterpressure plate 72. The damper 75 
between the flywheels 61 and 73 comprises two sets of arcuate energy 
storing elements in the form of coil springs which oppose rotation of the 
flywheels 61 and 73 relative to each other. A similar damper is described 
and shown in detail in the aforementioned commonly owned U.S. Pat. No. 
5,180,336 to Maucher et al. to which reference may be had, if necessary. 
An important advantage of the compensating unit 26 is that it can be 
readily incorporated into the clutch operating apparatus and occupies a 
small amount of space, not only in the direction of the axis X--X but also 
radially of such axis. In the apparatus 1 of FIGS. 1 to 7, the 
compensating unit 26 is installed between the carrier 4 and the support 9. 
However, it is also possible to install the compensating unit between the 
case of the transmission 2 and the carrier 4 (which is then movable 
relative to the transmission in the direction of the axis X--X) or between 
the carrier 4 and a member which is mounted on the case of the 
transmission 2. Furthermore, and while FIG. 1 shows that the actuator 11 
and the bearing 16 are two separately produced devices, it is also 
possible to make the bearing of one piece with such actuator; for example, 
the outer race 17 of the bearing 16 can be of one piece with the actuator 
11. The bearing 16 can constitute or can be replaced with a so-called 
self-centering bearing. 
The ratio of the force which is necessary to disengage the clutch 3 to the 
force which is required to engage the clutch can be selected to match a 
desired value by appropriate selection of the angles 40 and 39 which are 
shown in FIGS. 5 and 7, respectively. Furthermore, and as already 
mentioned above, the angle 39 and/or 40 need not be constant from end to 
end of the respective ramp 37, 38 or 33, 34. By varying the angle 39 
and/or 40 one can vary the aforementioned ratio during engagement or 
disengagement of the clutch. 
In addition to the previously discussed undertakings (such as sand blasting 
or ball peening) for preventing angular movements of the actuator 11, 
annular member 32 and/or element 69 in the wrong direction, it is also 
possible to achieve such result by appropriate selection of the friction 
characteristics of the parts which are provided with complementary cams 
and/or with complementary ramps and/or by appropriate selection of the 
angles of slope of the surfaces on the complementary cams and/or on the 
complementary ramps. All that counts is to ensure that the actuator 11, 
the annular member 32 and the annular element 69 act not unlike freewheels 
which can be rotated in one direction in response to the application of a 
relatively small force but cannot be rotated in the opposite direction 
(e.g., because of self-locking action which develops in automatic response 
to attempted rotation of the actuator 11, annular member 32 and annular 
element 69 in the other (i.e., wrong) direction). Proper selection of the 
materials of the complementary cams and ramps and/or proper finish of the 
sloping surfaces of the cams and ramps in order to achieve the 
aforementioned self-locking action is preferred at this time because the 
actuator 11, the annular member 32 and the annular element 69 can be 
prevented from turning in the wrong direction without the need for any 
additional parts which must be provided for the sole purpose of preventing 
any rotation of the actuator 11, member 32 and/or element 69 in the wrong 
direction. However the utilization of such additional parts which are 
designed to ensure that the actuator 11, the member 32 and the element 69 
will act not unlike freewheels is also within the scope of the present 
invention. 
The coil spring 43, which forms part of the compensating unit 26 and serves 
to rotate the element 69 in a direction to move such element toward the 
pressure plate 41 in order to compensate for wear upon the components 61, 
41, 27 or at least upon the component 27, is installed, configurated and 
stressed in such a way that it does not interfere with the function of the 
clutch spring 25 and/or diaphragm spring (sensor) 66. At the same time, 
the spring 43 should store sufficient amounts of energy to ensure that the 
axial position of the annular element 69 can be changed during the entire 
useful life of the apparatus 1 and clutch 3 in order to compensate for 
wear at least upon the friction linings 27. 
The clutch 3 of FIG. 1 is a push-type clutch because the operating means 
19a must be depressed toward the pressure plate 41 (rather than pulled in 
a direction away from the pressure plate) in order to disengage the 
clutch. 
FIG. 8 shows a modified clutch operating apparatus 101 which comprises a 
ring-shaped support 109 adapted to be affixed to a housing or the like by 
means of threaded fasteners 105 or in another suitable way. A ring-shaped 
actuator 111 of the apparatus 101 is mounted for rotation and for axial 
movement relative to the support 109. The means 112 for moving the 
actuator 111 relative to the support 109 in the axial direction of the 
apparatus 101 includes two sets of ramps or cams corresponding to the cams 
13 and 14 of the moving means 12 shown in FIG. 1 and rolling elements 115. 
The actuator 111 comprises an axial extension 111a which is surrounded by 
the axially extending portions 109a of the support 109. 
The apparatus 101 further comprises a bearing 116 having an inner race 118 
which can act upon the operating means of a clutch in the same way as 
described in connection with the race 18 of the bearing 16 and the clutch 
operating means 19a of the apparatus 1 and clutch 3 shown in FIG. 1. The 
bearing 116 is mounted on and has freedom of limited radial movement 
relative to a carrier 107. Such limited freedom of radial movement ensures 
that the bearing 116 can be automatically centered relative to the 
operating means of the clutch (not shown) which is to be operated by the 
apparatus 101. The compensating unit 126 of the apparatus 101 is mounted 
between the carrier 107 and the actuator 111 to move (when necessary) the 
bearing 116 in a direction to the left (as viewed in FIG. 8) in order to 
compensate for wear upon the pressure plate and the counterpressure plate 
and/or the friction linings of the clutch. 
The compensating unit 126 comprises two annular members 126a, 126b which 
are provided with sets of circumferentially extending ramps having 
surfaces which slope in the direction of the axis of the bearing 116, for 
example, in a manner as described in connection with the ramps 33, 34 of 
the annular member 32 and the ramps 37, 38 of the carrier 4 shown in FIG. 
1. The annular member 126a is carried by the actuator 111 and is 
preferably nonrotatably affixed thereto. The connection between the 
annular member 126a (which can be made of a plastic material) and the 
actuator 111 can comprise axially extending snap fasteners 130. The 
annular member 126b is (or can be) also made of a plastic material and is 
supported by the carrier 107 for the bearing 116. The carrier 107 is 
nonrotatably connected with but can move in the axial direction of the 
actuator 111. The annular member 126b is free to turn relative to the 
annular member 126a, actuator 111 and carrier 107. 
If the compensating unit 126 is to carry out its compensating action, the 
annular member 126b must be turned by at least one energy storing element 
143 (e.g., an arcuate coil spring). The radially outer portions of the 
convolutions of the arcuate energy storing element 143 abut an axially 
extending portion 131 of the annular member 126b. The portion 131 defines 
an arcuate radially outwardly extending channel or groove bounded by a 
concave surface which maintains the energy storing element 143 in a 
desired axial position relative to the annular member 126b. The energy 
storing element 143 reacts against the carrier 107 and bears upon the 
annular member 126b so that the member 126b is urged to turn relative to 
the annular member 126a. The carrier 107 is provided with at least one 
axially extending retainer 107a for one end convolution of the energy 
storing element 143. FIG. 8 shows that the energy storing element 143 is 
disposed radially inwardly of the moving means 112 and in at least partial 
radial alignment with the cams or ramps of the moving means 112. 
The means for turning the actuator 111 in order to move the bearing 116 in 
a direction toward the pressure plate of the clutch is shown in FIG. 9. 
The turning means can include a straight wire which can be made from a 
non-resilient material or (and as actually shown in FIG. 9) the turning 
means can comprise a substantially Z-shaped link or yoke 144 which can be 
flexed between its end portions 145 and 146 to an extent depending upon 
the magnitude of the applied forces. The link 144 is made of a resilient 
material so that it can reassume its normal shape when the intensity of 
the applied force is reduced, e.g., to zero. The Z-shaped configuration of 
the link 144 facilitates its flexing in response to the application of 
forces which are required to turn the actuator 111 for the purpose of 
disengaging the clutch, which has its operating means adjacent the race 
118 of the bearing 116. 
The link 144 extends through an opening 148 in a wall 147 forming part of 
the transmission housing. The end portion 145 of the link is coupled with 
the actuator 111 of the clutch operating apparatus 101, and the end 
portion 146 of the link 144 is coupled to the clutch pedal (not shown) or 
to an actuator or connecting element operating on the apparatus 1 and thus 
the clutch 3 (not shown) of a motor vehicle. Such a mode of coupling the 
actuator to a device which causes the actuator to move in order to 
initiate the disengagement of a clutch which is operated by the apparatus 
101 contributes to the simplicity of the apparatus. Furthermore, since the 
end portion 146 of the link 144 is adjacent to the exterior of the 
transmission housing, a bowden wire 149 connected to the clutch pedal is 
much less likely to be contaminated by impurities, such as fragments of 
the friction linings (which are produced as a result of wear upon the 
clutch disc) as well as other contaminants. Still further, the bowden wire 
149 is not exposed to elevated temperatures which develop in the housing, 
including the wall 147. 
Another important advantage of the link 144 is that it prevents the 
transmission of vibratory, oscillatory and/or other stray movements to the 
clutch pedal or actor when the clutch and the clutch operating apparatus 
are installed in a motor vehicle. Certain parts of the apparatus are 
likely to carry out undesirable stray movements in response to axial 
oscillations of the output element (e.g., a crankshaft or a camshaft) of 
the engine which drives the counterpressure plate of the clutch. Axial 
oscillations are the cause of self-induced vibratory or other stray 
movements of the pressure plate (such as the pressure plate 41 in the 
clutch 3 of FIG. 1). 
Still another important advantage of the structure which is shown in FIG. 9 
is that one can dispense with the customary disengaging lever which is 
necessary in conventional clutch operating apparatus to move the bearing 
relative to the operating means of the clutch. Such disengaging lever is 
normally mounted next to the transmission and constitutes a rather bulky 
component part which is likely to perform stray movements in response to 
vibration, oscillation and/or other stray movements of the output shaft of 
the prime mover. 
The rolling elements 15 of the moving means 12 shown in FIGS. 1 and 3, and 
the corresponding rolling elements 115 in the moving means 112 of FIG. 8 
exhibit the advantage that they prevent the development of play between 
the bearing 16 or 116 and the adjacent parts, particularly a tilting of 
the bearing relative to the adjacent parts. As shown in FIG. 2, the moving 
means 12 preferably comprises at least three equidistant rolling elements 
15. The same applies for the moving means 112 in the apparatus 101 of FIG. 
8. 
The moving means 12 and/or 112 can also serve as a means for balancing or 
as a means for compensating for tolerances in the axial direction of the 
apparatus 1 or 101. Otherwise stated, the moving means 12 and/or 112 can 
ensure that the combined axial length of the output element (e.g., the 
crankshaft) of the prime mover, the counterpressure plate (such as the 
composite flywheel 72 in the clutch 3 of FIG. 1), the position of the tips 
19a of the prongs 19 forming part of the clutch spring 25 relative to the 
counterpressure plate, the apparatus 1 or 101, and the distance from the 
wall of the transmission housing or case matches or closely approximates 
the desired or optimal axial length. 
FIGS. 10a and 10b illustrate two presently preferred configurations of the 
cams 13, 14 forming part of the moving means 12 or the cams forming part 
of the moving means 112. The character 150 denotes the bowden wire and the 
characters 151 and 151a respectively denote the slope angles of the 
confronting surfaces of the complementary cams. The angle 151 is constant 
and, therefore, the transmission in the direction of disengagement (arrow 
152) remains unchanged. If the confronting surfaces of the complementary 
cams are configurated in a manner as shown in FIG. 10b, the transmission 
in the direction of the arrow 152 varies in a manner as indicated at 151a. 
FIGS. 10a and 10b show that it is possible to select the progress of the 
clutch disengaging force in a manner which is best suited for a specific 
use of the combination of a clutch and the improved clutch operating 
apparatus. 
FIG. 11 illustrates a modified construction of the means for turning the 
actuator of the clutch operating apparatus for the purpose of moving the 
bearing 16 or 116 in order to change the condition of the clutch. The link 
144 of FIG. 9 is replaced by a resilient connector 144a' in the form of a 
coil spring having a set of convolutions 145a', a first end portion 145b' 
carrying a connector 145' for attachment to the actuator (such as 11), and 
a second end portion 146b' connectable at 146' to a pedal or actor by a 
bowden wire 149'. The connector 144a' constitutes an energy storing 
element which can store a desired amount of energy as a result of axial 
stressing. Thus, the coiled median portion of the stressed spring 144a' 
will undergo elastic deformation after the magnitude of the force acting 
upon the end portions 145b' and 146b' reaches a preselected value. An 
advantage of the resilient connector 144a' of FIG. 11 is that, when the 
apparatus including the structure of FIG. 11 is utilized in a motor 
vehicle, vibratory and/or other stray movements, which develop when the 
RPM of the engine is within a certain range or within one of several 
ranges and would normally be transmitted to the bowden wire 149', are 
damped or fully compensated for by the resilient element 144a'. The 
initial stressing of the resilient element 144a' can be between about 100N 
and 350N, depending upon the circumstances of use. 
FIG. 12 illustrates a further clutch operating apparatus 201 which 
comprises a support 209 connectable to the housing or case of a 
transmission having an input shaft 206, and an actuator 211. The support 
209 and the actuator 211 are made of a plastic material. A suitable 
plastic material is a thermoplast, such as a polyamide, and the plastic 
parts 209, 211 can be reinforced by embedding glass fibers and/or carbon 
fibers or other suitable fibers into the plastic material. A similar 
plastic material (with or without reinforcing fibers) can be utilized for 
the making of the annular member 226b of the wear compensating unit 226 as 
well as for the making of the annular member 126a and/or 126b forming part 
of the compensating unit 126 shown in FIG. 8. 
The spherical rolling elements 215 are in direct contact with the plastic 
support 209 and the plastic actuator 211. It is often desirable to provide 
at least one of the plastic parts 209, 211 with inserts (e.g., metallic 
inserts) which define the actual tracks being contacted by the rolling 
elements 215. In the embodiment of FIG. 12, the ramps of the wear 
compensating unit 226 are configurated in such a way that they constitute 
self-locking threads. The threads can be single threads or multiple 
threads. The actuator 211 carries a first thread and the annular member 
226b carries a second thread complementary to the first thread. The angle 
of slope of the helical ramps provided on the actuator 211 and annular 
member 226b can be in the range of between about 6.degree. and 20.degree., 
preferably between about 12.degree. and 18.degree., depending upon the 
desired transmission ratio. Such angle is defined by the ramps and a plane 
which is normal to the axis of rotation of the member 226b and other 
rotary constituents of the apparatus 201. It is presently preferred to 
select the angle in such a way that the ramps of the actuator 211 and 
annular member 226b are in self-locking engagement with each other in 
response to the application of a force in the axial direction of the 
compensating unit 226. Thus, the bearing, including the inner race 218 of 
FIG. 12, can be moved in a direction toward the pressure plate of the 
clutch which is being operated by the apparatus 201 only when the coil 
spring 243 of the unit 226 is free to turn the annular member 226b in a 
direction to advance the bearing so that the axial displacement of the 
bearing compensates for wear upon one or more components (particularly the 
friction linings) of the clutch. One end portion of the spring 243 reacts 
against the support 209 and its other end portion bears upon the annular 
member 226b. To this end, the end portions of the spring 243 extend 
radially of the axis of rotation of the member 226b and prevent the spring 
from turning relative to the actuator 211 and/or annular member 226b. 
As can be seen in FIG. 12, the coil spring 243 of the wear compensating 
unit 226 is disposed radially inwardly of the annular member 226b and its 
axis coincides with or is parallel to the axis of the input shaft 206 of 
the transmission. When the clutch which is controlled by the apparatus 201 
is engaged, the spring 243 causes the free end portion of the rotary inner 
race 218 of the bearing to apply a predetermined axial force to the tips 
of the prongs 219 (one shown in FIG. 12 by phantom lines). 
The rotary actuator 211 of the apparatus 201 shown in FIG. 12 comprises 
cams forming part of the moving means 212 as well as ramps or threads 
forming part of the compensating unit 226. The annular member 226b 
includes portions 227 forming part of a locking or blocking device 228 
which maintains the member 226b in a retracted position (with reference to 
the support 209) preparatory to and during mounting of the apparatus 201 
in a motor vehicle or another machine. The locking device 228 can be said 
to constitute a detent assembly including male detents 227 on the annular 
member 226b and complementary female detents 229 on the support 209. The 
female detents 229 include a set of tongues having recesses or sockets for 
the male detents 227. The resistance of the properly engaged locking or 
blocking device 228 must be overcome in response to initial actuation of 
the apparatus 201, i.e., the compensating unit 226 is operative upon the 
initial disengagement of the clutch which is operated by the apparatus 
201. The tongues of the female detents 229 are elastically deformable in 
the radial direction of the annular member 226b. 
The annular member 226b of the compensating unit 226 is further provided 
with axially parallel extensions 230 constituting handgrip portions which 
can be manipulated by the fingers of an operator who wishes to turn the 
member 226 relative to the support 209. The extensions or handgrip 
portions 230 can be manipulated by an operator upon removal of the engine 
and the transmission from a motor vehicle in order to return the annular 
member 226b to its retracted position in which it is separably coupled to 
the actuator 211 by the detents 227, 229 of the blocking device 228. The 
annular member 226b can remain locked to the support 209 until after the 
engine and the transmission as well as the power train between the output 
element of the engine and the input shaft 206 of the transmission are 
reinstalled in the motor vehicle. 
The clearance or gap 249 which develops between the support 209 and the 
actuator 211 during disengagement of the clutch by the bearing including 
the rotary inner race 218 can be at least nearly completely sealed by one 
or more sealing devices, e.g. by one or more covers or the like. For 
example, the support 209 and the actuator 211 can comprise axially 
extending portions which are slidably telescoped into each other. 
Reference may be had to FIG. 13 which shows an axially extending tubular 
portion 309a forming part of the support 309 and being slidably telescoped 
into the axially extending portion 311a of the actuator 311. 
As already described with reference to and shown in FIGS. 1, 8 and 12, the 
apparatus 1, 101 or 201 can be secured to the transmission case or housing 
by bolts or other suitable threaded fasteners (note the fasteners 5 in 
FIG. 1 and the fasteners 105 in FIG. 8). However, it is equally within the 
purview of the invention to replace the threaded fasteners (or to employ 
such threaded fasteners jointly) with other suitable coupling or attaching 
means. For example, the fasteners (such as 5 or 105) can be employed with 
or can be replaced by a device which can adequately mount the clutch 
operating apparatus on the case or housing of a transmission (such as the 
transmission 2 shown in FIG. 1) in response to axial movement of the 
apparatus relative to the input shaft of the transmission. Alternatively, 
the connection between the transmission case and the clutch operating 
apparatus can include complementary parts which can be moved into reliable 
frictional engagement with each other. The utilization of substitutes for 
or additions to threaded fasteners can contribute to significant 
simplification and lower cost of installation of the apparatus 1, 101, 201 
or equivalent apparatus under the hood of a motor vehicle. For example, 
the carrier 4 or the support 109 or 209 can be provided with axial 
extensions which can be caused to snap into complementary recesses or 
sockets of the transmission case to establish a frictional or form-locking 
connection between the transmission and the clutch operating apparatus. 
FIG. 12 shows that the apparatus 201 further comprises a snap-in or plug-in 
connection or coupling 245 between the member 244 (corresponding to the 
member 144 or 144a') and the ring-shaped actuator 211. The connection or 
coupling 245 permits some relative movements of the actuator 211 and the 
member 244. The illustrated coupling 245 comprises a spherical portion 246 
which is provided on the actuator 211 and a complementary socket or recess 
247 in an elastic member 248 preferably made of a plastic material and 
being secured to the member 244. The member 248 acts not unlike a clip and 
need not necessarily be made of a plastic material; for example, such 
member can be made (at least in part) of spring steel. 
As can be seen in FIGS. 8 and 12, the apparatus 101 and 201 can be provided 
with sealing elements 153 and 253, respectively. Such sealing elements are 
effective in the radial direction and establish simple but efficient seals 
between the case of a transmission (such as the transmission 2 shown in 
FIG. 1) and the input shaft (6 in FIG. 1, 206 in FIG. 12) of the 
transmission. The sealing elements 153, 253 are or can be mounted on the 
apparatus 101, 201 in the manufacturing plant so that they are ready to be 
slipped onto the input shaft and to engage the transmission case when the 
mounting of the apparatus in the power train between the transmission and 
the prime mover is completed. The element 153 or 253 then seals the 
clearance between the periphery of the input shaft and the case of the 
transmission. 
The clutch operating apparatus which includes the structure shown in FIG. 
13 includes a self-centering bearing 316 which is held by a resilient 
element 354, e.g., a diaphragm spring. The resilient element 354 includes 
axially extending tongues or prongs 355 which are or which can be welded 
to or made of one piece with the main portion of the element 354. The 
tongues 355 cooperate with complementary portions of a disc-shaped member 
356 carried by the annular member 326b of the compensating unit. The 
connection between the resilient element 354 and the disc-shaped member 
356 on the annular member 226b is self-locking in the axial direction. The 
member 356 is flat and is secured to the member 226b by an axial snap-on 
fastener device 357. The bearing 316 has some freedom of radial movement 
relative to the member 326b. 
The rolling elements (such as the elements 15 forming part of the moving 
means 12 shown in FIG. 1) can be installed in a cage (not specifically 
shown) which serves to maintain such rolling elements at a selected 
distance from each other as seen in the circumferential direction of the 
respective moving means. Such mounting of the rolling elements even 
further reduces the likelihood of undesirable tilting of the parts which 
are provided with the cams (such as 13 and 14) cooperating with the 
rolling elements to effect controlled axial movements of one of such parts 
relative to the other part. For example, a cage for the rolling elements 
15 in the moving means 12 of FIG. 1 reduces the likelihood of tilting of 
the actuator 11 (and hence the bearing 16) relative to the support 9. 
The improved clutch operating apparatus is susceptible of numerous 
additional modifications without departing from the spirit of the 
invention. For example, the features of the apparatus 1 of FIGS. 1 to 7 
can be combined or used interchangeably with the features of the apparatus 
shown in FIGS. 8, 12 and 13. Furthermore, the features of the illustrated 
and described clutch operating apparatus can be embodied in apparatus 
which are to be used to operate clutches other than that shown in FIG. 1, 
for example, clutches of the type disclosed in the aforementioned commonly 
owned U.S. patent applications. 
Still further, at least some of the features of the illustrated clutch 
operating apparatus or of the illustrated combinations of the improved 
apparatus with friction clutches or other suitable clutches are believed 
to be sufficiently novel and unobvious to warrant independent patent 
protection, either alone or in combination with certain other constituents 
of the apparatus. The same applies for the aforedescribed novel and 
improved methods of installing the apparatus in a motor vehicle or 
elsewhere, of combining the improved apparatus with a clutch, and of 
assembling the component parts of the improved apparatus. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of the prior art, fairly constitute essential 
characteristics of the generic and specific aspects of the above-outlined 
contribution to the art and, therefore, such adaptations should and are 
intended to be comprehended within the meaning and range of equivalence of 
the appended claims.