Self adjuster for push type clutch

In a push-type clutch, a facing wear adjustment nearly annular adjust ring with which an outer peripheral part of a diaphragm spring contacts from a side opposite to a flywheel is screwed into an inside face of a pressure plate so as to be movable in a clutch axial direction, so that a worm wheel is rotated by a bracket moving in a clutch axial direction to rotate the adjust ring when a facing is worn out. The adjust ring position can thus be adjusted automatically to a diaphragm spring side by a wear amount of the facing.

BACKGROUND OF THE INVENTION 
1. Industrial Useful Field 
This invention relates to a push-type clutch wherein a release bearing, to 
which an inner peripheral part of a diaphragm spring is coupled, is pushed 
toward a flywheel side and an outer peripheral part of the diaphragm 
spring is moved in the opposite direction, so as to release the clutch. 
This invention especially relates, in detail, to a self adjuster for 
automatic adjustment of the clutch as wear of facing occurs. 
2. Prior Art and Its Problem 
As regards the pull-type clutch equipped with the mechanism enabling the 
adjustment according to the wear of facing, such mechanism is shown in 
applicant's Japan Patent Application No. 61-142140. 
In such mechanism hereof, a diaphragm spring 5, a retainer 7, a lever 50 
(load transmission lever) and a pressure plate 2 are installed inside a 
clutch cover 4. Releasing operation is carried out by a release lever 6c 
through a sleeve 6a and a release bearing 6b which are coupled to the 
retainer 7. The retainer 7 is locked by a pin 7b, and the pin 7b is 
secured by a flange 7c to the clutch cover 4. 
In FIG. 10, 50a is an outside fulcrum point of the lever 50 and 51 is an 
inertial brake, 3 and 3 are clutch discs, 3a and 3a are clutch facings, 52 
is an intermediate plate and 1 is an engine flywheel. 
The lever 50 is interposed between the retainer 7 and an adjust ring 11 
threaded clutch cover 4. When the facings 3a and 3a of the clutch discs 3 
and 3 are worn out, the position of adjust ring 11 is adjusted in a clutch 
axial direction by turning a threaded part 11a of the adjust ring 11. 
Therefore, the adjusting work is troublesome. 
On the other hand, as regards an automatic adjusting device for a clutch, 
Japan Patent Application (KOKAI) No. 60-143228, based on U.S. Pat. No. 
4,549,643, is well known. This device is composed of the first boss member 
having a worm screw on its outer peripheral surface, a second boss member 
having a pin, and first and second coil springs connecting both boss 
members etc. Because both boss members are resiliently connected by 
elastic forces of the first and second coil springs, in such automatic 
adjusting device automatic adjustment can not be done smoothly. 
In applicant's Japanese Utility Model Applications No.1-4594 and No.1-4595, 
corresponding to U.S. Pat. No. 5,029,687, an adjuster for pull-type clutch 
enables an automatic position adjustment of the adjust ring and further 
enables a smooth adjustment thereof when the facings are worn out. In a 
push-type clutch, however, the above-mentioned self adjuster has been 
unknown. 
OBJECT OF THE INVENTION 
An object of the invention is to provide a self adjuster for push-type 
clutch which enables an automatic and smooth positional adjustment of an 
adjust ring when a facing is worn out. 
SUMMARY OF THE INVENTION 
In a push-type clutch wherein a release bearing, to which an inner 
peripheral part of a diaphragm spring is coupled, is pushed toward a 
flywheel side and moves an outer peripheral part of a diaphragm spring is 
an opposite direction to release the clutch; this invention provides a 
self adjuster for such push-type clutch, in which a facing wear adjustment 
ring for contact with an outer peripheral part of the diaphragm spring 
from a side of the spring facing the flywheel is threaded into the 
pressure plate so as to be movable in an axial direction relative to the 
clutch. A stay bracket, having two support lugs extending in the vicinity 
of an inside face of the adjust ring, with a specified width between the 
lugs in a clutch circumferential direction, is secured to the clutch cover 
with a pin between the lugs having opposite ends secured to the lugs 
support lugs. A worm wheel, having a worm threaded part on its outer 
peripheral surface, is fitted onto the pin adjacent one support lug so to 
be as freely rotatable on the pin. Ratchet external teeth, for one 
direction rotation of the worm wheel, are formed on a support lug side end 
portion of the worm wheel. A stopper, mating with the ratchet external 
teeth for preventing rotation of worm wheel in the reverse direction, is 
secured to the stay bracket. A sensing lever, having an arm extending in a 
radial direction of the clutch is mounted on the other support lug side of 
the pin and is freely rotatable in relation to the pin. A tip end of the 
arm of the sensing lever is located in a concave portion provided at an 
outer peripheral surface of a bracket connected to the release bearing. A 
ratchet tooth surface, for preventing the sensing lever from rotating but 
permitting rotation in the opposite direction relatively to the worm 
wheel, is formed on a worm wheel side end surface of the sensing lever. A 
spring member presses the sensing lever to the worm wheel side and a play 
creating mechanism gives the sensing lever, rotating with a movement of 
the bracket, a specified play relative to the worm wheel, such play being 
provided in order not to transmit a rotation of the sensing lever to the 
worm wheel, caused by a movement of the bracket during clutch 
engaging/releasing operation, before wear of the facing. A rack, which 
engages with the worm threaded part to move the adjust ring to the 
diaphragm spring side with a rotation of the worm threaded part after 
facing wear, is formed on an inside surface of the adjust ring. 
In this invention, when the facing is worn out, the sensing lever rotates 
with the movement of the bracket and the worm wheel is thereby rotated to 
cause the adjust ring to rotate. In this way, the adjust ring is 
automatically adjusted by the amount of wear of the facing.

EMBODIMENTS 
In FIG. 1, 1 is a flywheel, 2 is a pressure plate, 3 is a clutch disc 
having a facing 3a at its outer peripheral part, 4 is a clutch cover an 
outer peripheral part of which is secured to the flywheel 1, 5 is a 
diaphragm spring. 
A substantially adjustment annular ring 11 fits in an inside surface of a 
convex portion 2a protruding axially rearward from an outer peripheral 
part of pressure plate 2. The adjustment ring 11 is threaded into the 
convex portion 2a at a threaded part 11a in the axial direction of the 
clutch so as to allow positional adjustment. An outer peripheral part of 
the diaphragm spring 5 is in contact from a rear side of adjustment ring 
11 at a convex portion 11b protruding axially of the clutch and rearward 
from an outer peripheral part of adjustment ring 11. The diaphragm spring 
5 is supported by clutch cover 4 and is held between two wire rings 13a 
and 13b supported by a stud 12 at its approx. intermediate portion. The 
inner peripheral part of diaphragm spring 5 is coupled to a release 
bearing mechanism 6 in retainer. 
A self adjuster 20, forming an essential part of this invention, is 
described hereunder. FIG. 2 is the oblique exploded view of the self 
adjuster 20 and FIG. 3 is a view in the direction of arrow III of FIG. 1. 
The self adjuster 20 is composed of a stay bracket 21, a pin 22, a worm 
wheel 23, a sensing lever 24 and conned disc spring 26 etc. The stay 
bracket 21 is made of an approx. band-shaped steel plate and is bent into 
an U-shape in its vertical section. Its radial outside end portion is bent 
outward and its inside radial end portion is bent inward, as best shown in 
FIG. 1. Outside end portion 21c is secured by a screw 31a to the clutch 
cover 4 and an inside end portion 21d is secured by a screw 31b to clutch 
cover 4. outer portion 21a passes through an outside opening 5a of 
diaphragm spring 5 and an inner portion 21b passes through an inside 
opening 5b of diaphragm spring 5. Two support lugs 21e and 21f are 
integrally bent from forward in the clutch direction stay bracket 21 
radially inward of the adjustment ring 11 with a specified width left 
between such support lugs in a clutch circumferential direction. A pin 22 
is supported by the support lugs 21e and 21f; and a worm wheel 23, a 
sensing lever 24 and a conned disc spring 26 etc. are mounted on pin 22. 
Worm wheel 23 fits freely rotatably onto the pin 22 and is disposed in the 
vicinity of the support lug 21e between the two support lugs 21e and 21f. 
A worm threaded part 23a is formed on an outer peripheral surface of the 
central part of the worm wheel 23. Ratchet external teeth 23b are formed 
on a right end portion in FIG. 3 of the worm wheel 23 and are so formed as 
to engage with a stopper 25 fastened to the stay bracket 21 for allowing 
rotation of the worm wheel 23 only in a direction of arrow R (FIG. 2) and 
prevent rotation of the worm wheel 23 in the reverse direction. The 
stopper 25 is made of a leaf spring and its tip end is so urged as to 
engage with the ratchet external teeth 23b. Further, ratchet external 
teeth 23c are formed on a left end portion in FIG. 3 of the worm wheel 23. 
The sensing lever 24 fits freely rotatably onto the pin 22 at a left side 
(support lug 21f side) in FIG. 3 of the worm wheel 23. The sensing lever 
24 has an arm 24a extending radially inwardly in relation to the pin 22. 
Sensing pin 24b extends in parallel with the pin 22 and is mounted at the 
tip end of the arm 24a. A ratchet tooth surface 24c, mating with a ratchet 
tooth surface 23c of the worm wheel 23, is formed on a right end face in 
FIG. 3 of the sensing lever 24. These ratchet tooth surfaces 23c and 24c 
are so formed that they mate integrally each other when the sensing lever 
24 rotates in the direction of arrow R (FIG. 2) and slide over each other 
when sensing lever 24 rotates in the reverse direction. One pitch between 
teeth of the ratchet tooth surface 24c of the sensing lever 24 is set to 
.delta.2. A size of .delta.2 will be described hereinafter. 
The coned disc spring 26 (spring member) is compressibly installed between 
the left end face in FIG. 3 of the sensing lever 24 and the support lug 
21f, and urges sensing lever 24 toward the worm wheel 23. A coil spring 
etc. may be used in place of coned disc spring 26. 
Warm 23, the sensing lever 24 and the conned disc spring 26 are mounted 
between the support lugs 21e and 21f, and an end of the pin 22 secured by 
crimping work or by the ends and a nut etc. 
In FIG. 1, racks 11c, mating with the worm threaded part 23a of the worm 
wheel 23, are formed on an inner peripheral surface of the adjustment ring 
11 over the entire circumference thereof, so that the adjust ring 11 is 
rotated for movement in the axial direction, i.e. its positional 
adjustment, when the worm wheel 23 rotates. 
The sensing pin 24b of the sensing lever 24 is located in the concave 
portion 8a formed on the bracket 8 fastened by a screw 7a to the retainer 
7, with an axial play .delta.1 (FIG. 1) therebetween. The sensing lever 24 
is so disposed that, under a clutch engaging state before the facing 3a is 
worn, the sensing pin 24b contacts with a flywheel 1 side wall of the 
concave portion 8a, as shown in FIG. 1. The apexes of the teeth on the 
ratchet tooth surface 24c contact with the apexes of the teeth on the 
ratchet tooth surface 23c so that the ratchet tooth surface 24c is in a 
state where it is lifted above the ratchet tooth surface 23c as shown in 
FIG. 3. .delta.1 is set smaller than an axial moving distance L1(FIG. 1) 
of the bracket 8 accompanied by the releasing/engaging operation under 
ordinary state before wearing of the facing 3a, and .delta.2 is set equal 
to a rotating distance of the sensing lever 24 when the bracket 8 moves by 
a difference between L1 and .delta.1, while causing the sensing lever 24 
to rotate. By thus providing the plays .delta.1 and .delta.2 of the 
sensing lever 24 relative to the worm wheel 23, the play creating 
mechanism inhibits self adjuster 20 to carry out the positional adjustment 
of the adjust ring 11 when the facing 3a is not worn. 
Function will be described hereunder. FIG. 1 shows the clutch engaging 
state before wear on the facing 3a. It is assumed that the bracket 8 moves 
by a distance L1 in the axial direction (FIG. 1) up to a position shown by 
a chain line 81 in the engaging/releasing operation before wear on the 
facing 3a. In this instance, the self adjuster 20 functions as follows. 
When the bracket 8 moves by the distance L1 to the position 81 in the 
releasing operation, the sensing lever 24 rotates in the direction R by 
.delta.2 and sensing pin 24b contacts the side wall of the concave portion 
8a of the bracket 8 opposite the sidewall, because of the present of 
.delta.1 and .delta.2 are as mentioned above. However, the rotation of 
.delta.2 of the sensing lever 24 in the direction R is absorbed by the 
rotation of the ratchet tooth surface 24c until it mates with the ratchet 
tooth surface 23c. Thus, wheel 23 does not rotate, because one pitch 
between teeth on the ratchet tooth surface 24c of the sensing lever 24 is 
preset to .delta.2 and the sensing lever 24 is so disposed that, under the 
state of FIG. 1, the apexes of teeth on the ratchet tooth surface 24c 
contact with the apexes of teeth on the ratchet tooth surface 23c so that 
the ratchet tooth surface 24c is in the state where it is lifted above the 
ratchet tooth surface 23c. Further, when the bracket 8 is returned by the 
engaging operation from the position 81 to the state of FIG. 1, the 
sensing lever 24 rotates by .delta.2 in the direction reverse to R with 
the sensing pin 24b contacting with the flywheel 1 side wall of the 
concave portion 8a of the bracket 8. The ratchet tooth surface 24c slides 
and rotates by .delta.2 in relation to the ratchet tooth surface 23c so 
that the worm wheel 23 does not rotate. Consequently, the worm wheel 23 
does not rotate in the clutch engaging/releasing operation before wearing 
out of the facing 3a, so that adjustment ring 11 does not rotate and the 
positional adjustment by the self adjuster 20 is not carried out. 
In the clutch engaging state, it is assumed that the bracket 8 is moved by 
L2(FIG. 1) in the direction opposite to the flywheel 1 up to a position of 
chain line 82 due to wear of the facing 3a. When the bracket 8 is moved by 
L2 up to the position 82, the sensing lever 24 is rotated in the direction 
reverse to R by a distance corresponding to L2 with the sensing pin 24b 
contacting with the flywheel 1 side wall of the concave portion 8a of the 
bracket 8. In this instance, the apexes of teeth of the ratchet tooth 
surface 24c slide and rotate by a distance corresponding to L2 so as to 
get over several teeth of the ratchet tooth surface 23c to contact with 
new teeth. When the bracket 8 is released from the position 82 to the 
position 81, the sensing lever 24 is rotated together with the worm wheel 
23 in the direction R by a distance corresponding to the pitches gotten 
over by the ratchet tooth surface 24c while mating with the new teeth of 
the ratchet tooth surface 23c. When the worm wheel 23 rotates, the rack 
11c of the adjustment ring 11 is rotatably driven by the worm threaded 
part 23a, so that adjustment ring 11 is moved by means of screw pitches of 
the threaded part 11a to the diaphragm spring 5 side. Accordingly, the 
adjust ring 11 is moved to the diaphragm spring 5 side until the facing 3a 
comes into the initial state before wearing out of the facing 3a by 
repeating the clutch releasing/engaging operations, so that relative 
positional relations between the diaphragm spring 5, the adjusting ring 11 
etc. can be adjusted automatically. 
In the above-mentioned operation, reverse rotation of the worm wheel 23 is 
prevented so that there is no chance for the adjustment ring 11 to adjust 
its position to the opposite side (to the flywheel 1 side), because the 
ratchet external teeth 23b are formed on the worm wheel 23 and the stopper 
25 is installed. 
FIG. 4 is the vertical sectional view showing the push-type clutch equipped 
with the self adjuster of second embodiment of this invention. FIG. 5 is 
an exploded view before assembling the self adjuster of FIG. 4. FIG. 6 is 
the view viewed in the direction of arrow VI of FIG. 4. A self adjuster 
20a of the second embodiment is different from the self adjuster 20 of the 
first embodiment in the following point. 
In the self adjuster 20a; one pitch .delta.2 of teeth of the ratchet tooth 
surfaces 23c and 24c is made as small as possible, and the sensing lever 
24 is so disposed that, under a state of FIG. 4 i.e. under a clutch 
engaging state before wearing out of the facing 3a, the sensing pin 24b 
contacts with the flywheel 1 side wall of the concave portion 8a and the 
ratchet tooth surface 23c completely mates with the ratchet tooth surface 
24c. Further, in the state of FIG. 4, the play .delta.1 between the 
sensing pin 24b and an opposite to the flywheel 1 side wall of the concave 
portion 8a is preset to a distance equal to the axial moving distance L1 
(FIG. 4) of the bracket 8 accompanied by the releasing/engaging operation 
before wearing-out of the facing 3a. Namely, the play creating mechanism 
of the second embodiment is composed by providing the play .delta.1. Other 
structures are the same as those of the first embodiment, and symbols in 
FIG. 4 same as those of FIG. 1 to FIG. 3 correspond to the same or 
equivalent components. 
Function will be described hereunder. FIG. 4 shows the clutch engaging 
state before wear on the facing 3a. When the bracket 8 moves by the 
distance L1 (FIG. 4) in the axial direction up to the position of 81 in 
the engaging/releasing operation before wear on the facing 3a, the self 
adjuster 20a functions as follows. 
When the bracket 8 moves by the distance L1 up to the position 81 in the 
releasing operation, the sensing pin 24b only contacts the wall of the 
concave portion 8a of bracket 8 which is opposite to flywheel side 1. The 
sensing lever 24 does not rotate and worm wheel 23 does not rotate, 
because play is preset as .delta.1=L1. Further, when the bracket 8 is 
returned by the engaging operation from the position 81 to the state of 
FIG. 4, the sensing pin 24b contacts the flywheel 1 side wall of the 
concave portion 8a of the bracket 8, sensing lever 24 does not rotate and 
worm wheel 23 does not rotate. Consequently, the worm wheel 23 does not 
rotate in the clutch engaging/releasing operation before wear on the 
facing 3a. Adjustment ring 11 does not rotate and the positional 
adjustment by the self adjuster 20a is not carried out. 
In the clutch engaging state, when the bracket 8 is moved by L2(FIG. 4) in 
the direction opposite to the flywheel 1 up to the position 82 due to the 
wear of the facing 3a, the sensing lever 24 is rotated in the direction 
reverse to R by a distance corresponding to L2 with the sensing pin 24b 
contacting with the flywheel 1 side wall of the concave portion 8a of the 
bracket 8. In this instance, the apexes of teeth of the ratchet tooth 
surface 24c slide and rotate by a distance corresponding to L2 and contact 
with the ratchet tooth surface 23c. Bracket 8 is released from the 
position 82 to the position 81, and the sensing lever 24 is rotated, 
together with the worm wheel 23, in the direction R by the distance L2 
corresponding to the sliding distance of the ratchet tooth surface 24c 
relative to the ratchet tooth surface 23c. When the worm wheel 23 rotates, 
the rack 11c of adjustment ring 11 is rotatably driven by the worm 
threaded part 23a, so that adjustment ring 11 is moved by means of screw 
pitches of the threaded part 11a to the diaphram spring 5 side. 
Accordingly, adjustment ring 11 is moved to the diaphragm spring 5 side 
until the facing 3a comes into the initial state before wearing out of the 
facing 3a by repeating the clutch releasing/engaging operations. Thus, the 
relative positional relations between the diaphragm spring 5, adjustment 
ring 11 etc. is adjusted automatically. 
FIG. 7 is the vertical sectional view showing the push-type clutch equipped 
with the self adjuster of third embodiment of this invention. FIG. 8 is an 
oblique exploded view before assembling the self adjuster. FIG. 9 is a 
view in the direction of arrow IX of FIG. 7. A self adjuster 20b of the 
third embodiment is different from the self adjuster 20 of the first 
embodiment in the following point. 
In the self adjuster 20b, a spherical body 24c is provided at a tip end of 
an arm 24a of the sensing lever 24, and the spherical body 24c fits in the 
concave portion 8a (FIG. 7) of the bracket 8. A cylindrical free rotor 27 
(FIG. 8) is fitted freely rotatably onto the pin 22 between the worm wheel 
23 and the sensing lever 24, and a ratchet tooth surface 27b, mating with 
ratchet tooth surface 24c is formed on a sensing lever 24 side end face of 
free rotor 27. The ratchet tooth surfaces 24c and 27b are so formed that 
they function in the same way as the ratchet tooth surfaces 24c and 23c of 
the second embodiment. A projection 23d is formed on a left end portion in 
FIG. 9 of the flywheel 23 in place of the ratchet tooth surface, and a 
notch 27a, in which the projection 23d fits, is formed at the worm wheel 
23 side of the free rotor 27. A circumferential width .delta.3 of the 
notch 27a and a circumferential width .delta.4 of the projection 23d are 
so preset that a difference between .delta.3 and .delta.4 becomes equal to 
a rotation distance of the sensing lever 24 which rotates according to an 
axial movement L1 (FIG. 7) of the bracket 8 accompanied by the 
releasing/engaging operation, under the ordinary state, before wearing of 
the facing 3a. The plays .delta.3 and .delta.4 for the sensing lever 24 
and the free rotor 27, in relation to the worm wheel 23, are thus 
provided, so that the play creating mechanism for inhibiting the 
positional adjustment of the adjust ring 11 by the self adjuster 20b when 
the facing 3a is not worn can be composed. Stopper 25a has an elliptical 
disc-like body, including a sharp tip end, and is urged so that its tip 
end is mated with the ratchet external tooth 23b by a torsion spring 25b. 
Other structures are the same as those of the first and second 
embodiments, and symbols in FIG. 8 same as those of FIG. 1 through FIG. 6 
correspond to the same or equivalent components. 
Function will be described hereunder. FIG. 7 shows the clutch engaging 
state before wearing of the facing 3a. When the bracket 8 moves by the 
distance L1 (FIG. 4) in the axial direction up to the position of 81 in 
the engaging/releasing operation before wearing of the facing 3a, the self 
adjuster 20b functions as follows. 
When the bracket 8 moves by the distance L1 up to the position 81 in the 
releasing operation, the sensing lever 24 rotates by a distance 
corresponding to L1, in the direction R, because the spherical body 24c 
fits in the concave portion 8a of the bracket 8. Since the ratchet tooth 
surface 24c of the sensing lever 24 mates with the ratchet tooth surface 
27b of the free rotor 27 in the direction R, the sensing lever 24 rotates 
together with the free rotor 27 by the distance corresponding to L1 in the 
direction R. However, since .delta.3 of the notch 27a and .delta.4 of the 
projection 23d are preset as described above, rotations of the sensing 
lever 24 and the free rotor 27 are absorbed by the difference between 
.delta.3 and .delta.4 and are not transmitted to the worm wheel 23 so that 
the worm wheel 23 does not rotate. Further, when the bracket 8 is returned 
by the engaging operation from the position 81 to the state of FIG. 7, the 
ratchet tooth surface 24c of the sensing lever 24 slides and rotates in 
relation to the ratchet tooth surface 27b so that the free rotor 27 and 
the worm wheel 23 do not rotate. Consequently, the worm wheel 23 does not 
rotate in the clutch engaging/releasing operation before wearing of the 
facing 3a, so that the adjust ring 11 does not rotate and the positional 
adjustment by the self adjuster 20c is not carried out. 
In the clutch engaging state, when the bracket 8 is moved by L2 (FIG. 7) in 
the direction opposite to the flywheel 1 up to the position 82 due to the 
wear of the facing 3a, the ratchet tooth surface 24c of the sensing lever 
24 slides and rotates, by a distance corresponding to L2, relatively to 
the ratchet tooth surface 27b so as to contact newly with the ratchet 
tooth surface 27b. When the bracket 8 is released from the position 82 to 
the position 81, the sensing lever 24 is moved together with the free 
rotor 27 in the direction R with the ratchet tooth surface 24c newly mated 
with the ratchet tooth surface 27b. This rotation distance is a sum of 
distance corresponding to L1 and distance corresponding to L2. The 
distance corresponding to L1 is absorbed by the difference between 
.delta.3 and .delta.4 but that corresponding to L2 is not absorbed, so 
that the sensing lever 24 and the free rotor 27 rotate together with the 
worm wheel 23 by the distance corresponding to L2. As the worm wheel 23 
rotates, the rack 11c of the adjust ring 11 is rotatably driven by the 
worm threaded part 23a so that the adjust ring 11 is moved to the 
diaphragm spring 5 side by means of the screw pitch of the threaded part 
11a. Accordingly, the adjust ring 11 is moved to the diaphragm spring 5 
side until the facing 3a comes into the initial state before wearing out 
of the facing 3a by repeating the clutch releasing/engaging operations, so 
that the relative positional relations between the diaphragm spring 5, the 
adjusting ring 11 etc. can be adjusted automatically. 
The number of above-mentioned self adjuster 20 (20a, 20b) of the first 
through third embodiments is not limited to only one for each clutch, but 
may be plural. 
In the self adjuster 20 (20a, 20b) of this invention, as described above, 
the release bearing mechanism 6, to which the inner peripheral part of the 
diaphragm spring 5 is coupled, is pushed toward the flywheel 1 side and 
the outer peripheral part of the diaphragm spring 5 is moved to the 
opposite direction to release the clutch; characterized by that the facing 
wear adjustment ring 11 is threaded into the inside face of the pressure 
plate 2 so as to be movable in the clutch axial direction. The worm wheel 
23 is rotated, by the bracket 8 moving in the clutch axial direction, so 
as to rotate the adjust ring 11 when the facing 3a is worn. Therefore, the 
adjust ring 11 can be adjusted its position automatically to the diaphragm 
spring 5 side by the wear amount of the facing 3a. Accordingly, even after 
the facing 3a is worn, a pressing load of the diaphragm spring 5 onto the 
facing 3a, the torque capacity of the clutch and the treading force on 
clutch pedal etc. can be maintain at substantially the same values before 
of the clutch facing. Further, in a clutch disc wherein a wear clearance 
of the facing 3a is increased, it becomes possible to allow the clutch 
cover 4 to operate up to the full wear clearance of the facing 3a. 
Moreover, the service life of the clutch can be prolonged.