Self-adjusting release mechanism for a clutch assembly

A self-adjusting release mechanism for a clutch assembly for automatically adjusting the increased or decreased displacement of a release bearing in a clutch mechanism. The release bearing is normally spaced from release levers of the clutch mechanism but engageable with the release levers to effect disengagement of the driving connection between driving and driven shafts when the clutch assembly is actuated. The self-adjusting release mechanism has a retainer mechanically connected to a clutch pedal of the assembly. The retainer has a hollow portion with at least one end open through which is positioned one end of a rod member that has its other end mechanically connected to the release bearing. A cam member is disposed in the hollow portion between the retainer and the rod member for selective engagement and disengagement with the rod member in response to the relative movement between the cam and the retainer. The cam member is biased toward disengagement from the rod member, while a pair of springs urge the cam member to a predetermined position when the cam member is disengaged from the rod member. Another spring biases the rod member in a clutch-disengaging direction.

BACKGROUND OF THE INVENTION 
This invention relates to a clutch assembly and, more particularly, to a 
self-adjusting release mechanism for a clutch assembly. 
In the prior art, there has been developed a self-adjusting release 
mechanism for a clutch assembly which includes a first member responsive 
to a clutch pedal, a second member operatively connected with a release 
bearing in a clutch mechanism and a third member selectively connecting 
and disconnecting the first and second members for adjusting a gap formed 
between a release lever in the clutch mechanism and the clutch release 
bearing. The third member has racks which are adapted for engagement with 
one of the first and second members. The third member is normally urged by 
a leaf spring in a disengaging direction. 
In the above conventional mechanism, an inner wall of its housing is used 
to limit the disengaging movement of the third member due to the leaf 
spring. In other words, the outer periphery of the third member is brought 
into contact with the inner wall because of the bias of the leaf spring. 
This mechanism further teaches that the inner wall has a recess into which 
the third member is urged by the leaf spring for effecting disengagement 
of the racks of the third member from the first or second member. Upon 
this disengagement, the first and second members move relative to one 
another so as to adjust the gap between the clutch release lever and the 
clutch release bearing. After the gap has been adjusted, the third member 
has to jump a shoulder defining the recess in the wall against the biasing 
force of the leaf spring in order to re-establish the engagement between 
the third member and the first or second member. 
The structure of the conventional mechanism previously referred to does not 
produce satisfactory results in that there is considerable wearing of the 
inner wall of the housing and the outer periphery of the third member and 
the first or second members due to the sliding movement between these 
engaging portions. Therefore, the proper and accurate adjusting function 
of the release mechanism is not always maintained and cannot be depended 
upon. The above construction of the conventional release mechanism also 
causes a drag on the manipulating or depression force on the clutch pedal 
due to the sliding resistance generated between the inner wall of the 
housing and the third member. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of this invention to provide a self-adjusting 
release mechanism for a clutch assembly which obviates the various 
deficiencies of the conventional release mechanisms. 
It is another object of this invention to provide a self-adjusting release 
mechanism for a clutch assembly which is durable by reducing the number of 
sliding engageable elements. 
It is still another object of this invention to provide a self-adjusting 
release mechanism for a clutch assembly which is actuated by a relatively 
small manipulating or depression force on a clutch pedal. 
It is a further object of this invention to provide a self-adjusting 
release mechanism for a clutch assembly which minimizes an idle or 
accidental actuating stroke of the clutch pedal. 
It is still a further object of this invention to provide a self-adjusting 
release mechanism for a clutch assembly which ensures that its elements 
are maintained in their predetermined or desired positions during clutch 
engagement. Additional objects and advantages of the invention will be set 
forth in part in the description which follows, and in part will be 
obvious from the description, or may be learned by practice of the 
invention. The objects and advantages of the invention may be realized and 
attained by means of the instrumentalities and combinations particularly 
pointed out in the appended claims. 
To achieve the foregoing objects and in accordance with the purpose of the 
invention, as embodied and broadly described herein, the clutch assembly 
of the invention comprises (1) clutch means for normally effecting a 
driving connection between the shafts; (2) clutch release levers actuable 
for disengaging the driving connection normally effected by the clutch 
means between the shafts; (3) clutch release bearing means normally spaced 
from the release levers and engageable with the release levers for 
effecting the disengagement of the driving connection between the shafts; 
(4) means for actuating the clutch assembly; and (5) means for 
automatically adjusting the space between the clutch release levers and 
the clutch release bearing means to a predetermined distance, the 
automatically adjusting means including (a) first retainer means 
mechanically connected to the actuating means and having a hollow portion 
therein open at least at one end; (b) a rod member mechanically connected 
to the clutch release bearing means for moving the clutch release bearing 
means relative to the clutch release levers and having a portion 
positioned through the open end of the first retainer means; (c) cam means 
disposed in the hollow portion between the first retainer means and the 
rod member for selective engagement and disengagement with the rod member 
in response to the relative movement between the cam means and the first 
retainer means, the cam means being under bias toward disengagement from 
the rod member; (d) first spring means for urging the cam means to a 
predetermined position when the cam means is disengaged from the rod 
member; and (e) second spring means for biasing the rod member in the 
clutch-disengaging direction. 
Preferably, the first retainer means has cam surfaces for urging the cam 
means into engagement with the rod member, and wherein the clutch assembly 
further comprises leaf spring means for providing the bias toward 
disengagement of the cam means from the rod member. 
It is also preferred that the clutch assembly further comprises second 
retainer means slidable relative to the rod member and operatively 
connected to the cam means, and wherein the first spring means includes a 
pair of springs acting on opposing sides of the second retainer means, the 
biasing forces of the pair of springs being balanced when the retainer 
means is in a predetermined neutral position. 
Finally, it is preferred that the clutch assembly further include a wire 
mechanically connecting the first retainer means to the actuating means, 
and third spring means for urging the wire to a taut condition, the first 
retainer means thereby being urged to a predetermined position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Reference will now be made in detail to the present preferred embodiments 
of the invention, examples of which are illustrated in the accompanying 
drawings. 
Referring to FIG. 1, in accordance with the invention, the clutch assembly 
connects driving and driven shafts and comprises a clutch mechanism 14, 
means 5 for actuating the clutch assembly, and a self-adjusting mechanism 
16. 
Preferably, the means 5 for actuating the clutch assembly comprises a 
clutch pedal 10 pivotally mounted on a stationary part of a vehicle body 
through a suitable pivot means-11. A return spring 12, which is positioned 
between the clutch pedal 10 and the vehicle body, biases the clutch pedal 
10 in the counterclockwise or engaging direction so that the clutch pedal 
10 is normally brought into contact with a stop means 13 mounted on the 
vehicle body. The clutch pedal 10 is operatively connected to the clutch 
mechanism 14 through a wire cable 15 and the self-adjusting mechanism 16. 
In accordance with the invention, the clutch mechanism 14 comprises clutch 
means for normally effecting a driving connection between the shafts, 
clutch release levers actuable for disengaging the driving connection 
normally effected by the clutch means between the shafts, and clutch 
release bearing means normally spaced from the release levers and 
engageable with the release levers for effecting the disengagement of the 
driving connection between the shafts. 
In the preferred embodiment, a flywheel 18 is secured to a driving shaft 
17, and a clutch release bearing 20 is disposed about an output or driven 
shaft 19. A clutch cover 21 and a pressure plate 22 are connected to the 
flywheel 18 for rotation therewith. A driven disc 23 has on its opposite 
sides inner and outer friction facings 24. Cushioning springs 25 are 
splined to the output shaft 19 and are positioned between the flywheel 18 
and the pressure plate 22. A clutch release lever 26 is disposed on the 
cover 21 so that its outer periphery normally applies a force for clutch 
engagement on the pressure plate 22 while its inner periphery is normally 
spaced from the release bearing 20. 
A clutch release fork 27 is pivotally mounted through a pivot pin 28 on a 
housing of the clutch mechanism 14 and is normally biased in the 
counter-clockwise or engaging direction by a return spring 29 which is 
arranged between the clutch release fork 27 and the clutch housing. The 
lower end of the clutch release fork 27 is mechanically connected to the 
self-adjusting mechanism 16 so that the clutch release fork 27 is moved in 
the clockwise or disengaging direction against the biasing force of the 
spring 29 when the clutch pedal 10 is depressed. 
The clutch release fork 27 is also operatively connected to the clutch 
release bearing 20 so that a predetermined clockwise movement of the 
release fork 27 brings the clutch release bearing 20 into contact with the 
inner periphery of the clutch release lever 26. By this movement, the 
outer periphery of the clutch release lever 26 is urged in the direction 
in which the pressure plate 22 is moved through spring clips 30 for 
effecting a clutch disengagement with the driven disc 23. Since clutch 
mechanism 14 may be constructed in a manner such as that taught in U.S. 
Pat. No. 3,235,049, any further explanation of the clutch operation can be 
obtained by reference to that disclosure. 
In accordance with the invention, the self-adjusting mechanism 16 comprises 
means for automatically adjusting the space between the clutch release 
levers 26 and the clutch release bearing means 20 to a predetermined 
distance. The automatically adjusting means includes: first retainer means 
mechanically connected to the clutch-actuating means 5 and having a hollow 
portion therein open at least at one end; a rod member mechanically 
connected to the clutch release bearing means 20 for moving the clutch 
release bearing means 20 relative to the clutch release levers 26 and 
having a portion positioned through the open end of the first retainer 
means; cam means disposed in the hollow portion between the first retainer 
means and the rod member for selective engagement and disengagement with 
the rod member in response to the relative movement between the cam means 
and the first retainer means, the cam means being under bias toward 
disengagement from the rod member; first spring means for urging the cam 
means to a predetermined position when the cam means is disengaged from 
the rod member; and second spring means for biasing the rod member in the 
clutch-disengaging direction. 
Referring now to the preferred embodiment shown in FIG. 2, the 
self-adjusting mechanism 16 includes a housing 31 having a large 
cylindrical section 32 and a small section 33. The large section 32 has a 
first end oriented toward the release fork 27 and a second end oriented 
toward the clutch-actuating means 5, the first and second ends being 
hereafter referred to as right and left ends, respectively, as shown in 
FIG. 2. 
The small section 33 has a flange 34 which is secured to the right open end 
of the large section 32. On the outer periphery of the small section 33 is 
a screw portion 35 into which a nut 36 is threaded to secure the housing 
31 to the clutch mechanism housing. The large section 32 has a left open 
end into which is threaded an end cable 37. The wire cable 15, connected 
at one end to the actuating means 5, is secured at its other end through 
the end cable 37. The end cable 37 is provided with a hollow portion 
therein for slidably receiving an end wire 38 which is connected to an end 
of a wire 39 of the wire cable 15. 
Preferably, the rod member of the self-adjusting mechanism 16 comprises a 
rod 40 formed with a right end having a slit 41 into which the clutch 
release fork 27 (FIG. 1) of the clutch mechanism 14 is positioned. This 
mechanically connects the rod 40 to the clutch release bearing means 20 
for moving the clutch release bearing means 20 relative to the clutch 
release levers 26. The other or left end of the rod 40 extends to an axial 
bore 42 of the end wire 38, with the rod 40 being slidable relative to the 
end wire 38. 
Preferably, the first retainer means of the self-adjusting mechanism 16 
comprises a retainer 43 which is threaded at one end onto an enlarged 
portion 44 of the end wire 38. The retainer 43 has a hollow portion 
through which is positioned the rod 40. 
Preferably, the cam means of the self-adjusting mechanism 16 comprises a 
pair of cam members 45 disposed in the hollow portion of the retainer 43 
between a concave inner surface of the retainer 43 and the outer surface 
of the rod 40 for selective engagement and disengagement with the rod 40 
in response to the relative movement between convex outer surfaces of the 
cam members 45 and the retainer 43. 
Preferably, a second retainer means 46 is operatively connected to the cam 
members 45 through means of leaf springs 47 which urge the cam members 45 
outwardly away from the rod 40. The second retainer means 46 is arranged 
between an inner wall of the large section 32 and the rod 40, and is 
slidable relative to the rod 40 and the inner wall. 
It is preferred that the cam members 45 have racks or teeth 48 on the 
surface facing the rod 40 which are adapted for engagement with racks or 
teeth 49 provided on the outer periphery of the rod 40. The concave inner 
surface of the retainer 43 has first cam surfaces 50 and second cam 
surfaces 51 which are adapted for engagement, respectively, with first and 
second portions 52 and 53 of the convex outer surfaces of the cam members 
45. The first cam surfaces 50 are spaced from the second cam surfaces 51 
of the retainer 43 by a predetermined distance so that the racks 48 of the 
cam members 45 are disengaged from the racks 49 of the rod 40 by the 
biasing force of the leaf springs 47 when the cam members 45 are moved 
relative to the retainer 43 from their first position wherein the first 
portions 52 of the cam members 45 engage with the first cam surfaces 50 of 
the retainer 43 to their second position wherein the second portions 53 of 
the cam members 45 engage the second cam surfaces 51 of the retainer 43. 
During operation the cam members 45 also move in a reverse direction from 
their second position to their first position as explained hereafter. 
Preferably, the second spring means of the self-adjusting mechanism 16 
comprises a spring 54 for urging the rod 40 toward the left. The spring 54 
has one end seated against a shoulder on the small section 33 of the 
housing and the other end seated against a shoulder on the rod 40, the 
biasing force of the spring 54 being greater than that of the return 
spring 29 of the clutch mechanism 14 shown in FIG. 1. 
Preferably, the first spring means for urging the cam means comprises a 
spring 55 inserted between the second retainer means 46 and the flange 34 
for urging the second retainer means 46 toward the left and a spring 56 
inserted between the second retainer means 46 and the end cable 37 for 
urging the second retainer means 46 toward the right. The biasing forces 
of the springs 55 and 56 are balanced when the second retainer means 46 is 
in a neutral position designated in FIG. 2 as N. 
As will be described hereinafter, the structure of the self-adjusting 
mechanism 16 corrects the space between the clutch release lever 26 and 
the clutch release bearing 20 to a predetermined distance, upon operation 
of the clutch assembly, when one of several conditions exist, i.e., when 
the space between the clutch release lever 26 and the clutch release 
bearing 20 is less than the predetermined distance or when the space 
between the clutch release lever 26 and the clutch release bearing 20 is 
larger than the predetermined distance. The various interactions and 
movements of the elements of the clutch assembly under the above 
conditions during operation when the clutch pedal 10 is depressed or 
released is now explained in greater detail. 
Referring now to FIGS. 1 and 2, during operation of the clutch assembly 
when the clutch pedal 10 is depressed downwardly or in the clockwise 
direction, the wire 39 of the wire cable 15, the end wire 38, and the 
retainer 43 are moved toward the left. The rod 40, the cam members 45, the 
leaf springs 47, and the second retainer means 46 follow the leftward 
movement of the retainer 43 because of the biasing forces of the springs 
54 and 55. This results in the leftward or clockwise rotation of the 
clutch release fork 27 so that the clutch release bearing 20 is moved 
toward the clutch release lever 26. 
If the clutch release bearing 20 contacts the clutch release lever 26 
before the second retainer means 46 is moved left to the neutral position 
N., i.e., the gap between the clutch release bearing 20 and the clutch 
release lever 26 is less than the predetermined distance, the biasing 
force of the clutch release lever 26 limits and prevents the leftward 
movements of the clutch release bearing 20, the fork 27 and the rod 40. 
Due to the engagement between the racks 49 of the rod 40 and the racks 48 
of the cam members 45, the cam members 45, the leaf springs 47 and the 
second retainer means 46 are prevented from also moving leftwardly. 
However, since retainer 43 is continuously moved toward the left by the 
pull from the wire cable 15, the first cam surfaces 50 of the retainer 43 
are moved leftwardly so as to disengage from the first portions 52 of cam 
members 45. Thus the cam members 45 are urged outwardly by the leaf 
springs 47 so that the racks 48 of the cam members 45 disengage from the 
racks 49 of the rod 40. The cam members 45, the leaf springs 47, and the 
second retainer means 46 are moved again leftwardly relative to the rod 40 
by the biasing force of the spring 55. 
When the second retainer means 46 reaches its neutral position N, the 
biasing forces of the springs 55 and 56 are balanced so that the second 
retainer means 46, the cam members 45 and the leaf springs 47 are 
prevented from moving further to the left. By the further movement of the 
retainer 43, the second cam surfaces 51 of the retainer 43 are brought 
into contact with the second portions 53 of the cam members 45 whereby the 
cam members 45 are urged inwardly against the outward force of the leaf 
springs 47 to again establish engagement between the racks 48 of the cam 
members 45 and the racks 49 of the rod 40. 
It should be noted that the racks 48 and 49 re-engage when the cam members 
45 are moved relative to the retainer 43 by the distance between the 
neutral position of the second retainer means 46 and the position when the 
racks 48 of the cam members 45 are disengaged from the racks 49 of rod 40. 
After the above re-engagement, the rod 40, the cam members 45, the leaf 
springs 47, and the second retainer means 46 will move together with the 
retainer 43 so that the outer periphery of the clutch release lever 26 is 
urged to the clutch release position. 
When the clutch pedal 10 is released, the clutch release bearing 20, the 
fork 27, the rod 40, the cam members 45, the leaf springs 47, the 
retainers 46 and 43, the end wire 38, the wire 39, and the clutch pedal 10 
are urged to return to their original positions by the biasing forces of 
the clutch release lever 26 and the springs 29, 56 and 12. When the second 
retainer means 46 is returned in its neutral position N, there is no 
further biasing force of the clutch release lever 26 exerted on the clutch 
release bearing 20 and the biasing forces of springs 55 and 56 are 
balanced. Therefore, the spring 54 prevents the further rightward 
movements of the clutch release bearing 20, the fork 27, the rod 40, cam 
members 45, leaf springs 47, and the second retainer means 46. However, 
the retainer 43 continues to move toward the right by the biasing force of 
the return spring 12. 
Therefore, the second cam surfaces 51 of the retainer 43 are moved away 
from or rightwardly relative to the second portions 53 of the cam members 
45. This results in the racks 48 of the cam members 45 disengaging from 
the racks 49 of the rod 40 by the outward urging force of the leaf springs 
47. At this time, there is no relative movement between the cam members 45 
and the rod 40 because the biasing forces of the springs 55 and 56 are 
balanced and the cam members 45 are disengaged from the retainer 43 and 
the rod 40. 
As the first cam surfaces 50 of the retainer 43 come into contact with the 
first portions 52 of the cam members 45 by the further rightward movement 
of the retainer 43, the cam members are urged again inwardly so that the 
racks 48 of the cam members 45 re-engage the racks 49 of the rod 40. 
Thereafter, the cam members 45, the leaf springs 47, the second retainer 
means 46 and the rod 40 will move together rightwardly with the retainer 
43 so that the clutch release fork 27 and the clutch release bearing 20 
are returned to their original positions. Thus, the space between the 
clutch release bearing 20 and the clutch release lever 26 is maintained at 
the predetermined distance which corresponds to the distance between the 
neutral position N of the second retainer means 46 and the original 
position of the second retainer means 46 illustrated in FIG. 2. 
If, during the operation of the clutch assembly when the clutch pedal 10 is 
depressed, the clutch release bearing 20 does not contact the clutch 
release lever 26 by the time the second retainer means 46 is moved to the 
neutral position N, namely, i.e., the gap between the clutch release 
bearing 20 and the clutch release lever 26 is larger than the 
predetermined distance, the clutch release bearing 20, the fork 27, the 
rod 40, the cam members 45, the leaf springs 47, and the second retainer 
means 46 continue to follow the leftward movement of the retainer 43 
because of the biasing force of the spring 54. When the clutch release 
bearing 20 contacts the clutch release lever 26, the biasing force of the 
clutch release lever 26 limits and prevents the movements of the clutch 
release bearing 20, the fork 27, the rod 40, the cam members 45, the leaf 
springs 47, and the second retainer means 46, 
However, since the retainer 43 continues leftwardly by the pull of the wire 
cables, the relative movement between the retainer 43 and the cam members 
45 causes the disengagement between the racks 48 of the cam members 45 and 
the racks 49 of the rod 40 by the biasing force of the leaf springs 47. 
Under this condition, the cam members 45, the leaf springs 47 and the 
second retainer means 46 are moved toward the right by the biasing force 
of the spring 56 because there is a gap between the second cam surfaces 51 
of the retainer 43 and the second portions 53 of the cam members 45. The 
second portions 53 of the cam members 45 eventually contact the second cam 
surfaces 51 of the retainer 43. Consequently, the cam members 45 are urged 
inwardly by the second cam surfaces 51 of the retainer 43 against the 
outward force of the leaf springs 47 so that the racks 48 of the cam 
members 45 re-engage with the racks 49 of the rod 40. 
It should be noted that the distance of the rightward movement of the cam 
members 45 is less than that distance between the neutral position of the 
second retainer means 46 and the position of the second retainer means 46 
when the racks 48 of the cam members 45 are disengaged from the racks 49 
of the rod 40. As is clear from above, the racks 48 of the cam members 45 
move rightwardly toward the neutral position of the second retainer means 
46 from the position when the racks 48 were disengaged from racks 49. 
After the re-engagement, the rod 40, the cam members 45, the leaf springs 
47, and the second retainer means 46 will move leftwardly together with 
the retainer 43 to effect clutch disengagement. 
When the clutch pedal 10 is released, the clutch release bearing 20, the 
fork 27, the rod 40, the cam members 45, the leaf springs 47, the 
retainers 46 and 43, the end wire 38 and the wire 39 return toward their 
original positions. When the elements return to positions corresponding to 
the positions when the racks 48 of the cam members 45 were engaged with 
the racks 49 of the rod 40 during depression of the clutch pedal 10, there 
is no biasing force of the clutch release lever 26 being exerted on the 
clutch release bearing 20. Accordingly, the clutch release bearing 20, the 
fork 27, the rod 40, the cam members 45, the leaf springs 47, and the 
second retainer means 46 are prevented from further moving rightwardly by 
the leftward biasing force of the spring 54. However, the retainer 43 
moves rightwardly relative to the cam members 45 to establish 
disengagement between the racks 48 of the cam members 45 and the racks 49 
of the rod 40. 
If the second retainer means 46 does not return to its neutral position 
upon the above disengagement, the cam members 45, the leaf springs 47, and 
the second retainer means 46 follow the return rightward movement of the 
retainer 43 because of the rightward biasing force of the spring 56 
relative to the rod 40. Although the movement of the cam members 45 is 
stopped when the second retainer means 46 reaches its neutral position, 
the retainer 43 continues to move rightwardly under action of the return 
spring 12 and the wire cable 15 so that the first cam surfaces 50 of the 
cam members 45 are brought into contact with the first portions 52 of the 
retainer 43 to again establish the engagement between the racks 48 of the 
cam members 45 and the racks 49 of the rod member 40. Thereafter, the cam 
members 45, the leaf springs 47, the second retainer means 46 and the rod 
40 will move rightwardly together with the retainer 43 so that the clutch 
release bearing 20 is spaced from the clutch release lever 26 by the 
predetermined distance. 
If the gap between the clutch release bearing 20 and the clutch release 
lever 26 is considerably large, the clutch release bearing 20, the fork 
27, the rod 40, the cam members 45, the leaf springs 47, and the second 
retainer means 46, as previously described when the clutch pedal 10 is 
depressed, will follow the movement of the retainer 43 because of the 
biasing force of the spring 54 beyond the neutral position of the second 
retainer means 46. When the gap is considerably large, the sum of the 
biasing forces of the springs 56 and 29 is such that it balances with the 
sum of the biasing force of the springs 54 and 55 before the clutch 
release bearing 20 is brought into contact with the clutch release lever 
26. Therefore, the clutch release bearing 20, the fork 27, the rod 40, the 
cam members 45, the leaf springs 47, and the second retainer means 46 are 
limited from further leftward movement even without the biasing force of 
the clutch release lever 26. This means, as previously described, that the 
racks 48 of the cam members 45 become disengaged from the racks 49 of the 
rod 40 because of the continued leftward movement of the retainer relative 
to the cam members 45 and the outwardly biasing force of the leaf springs 
47. 
If, at this time, there is the gap between the second cam surfaces 51 of 
the retainer 43 and the second portions 53 of the cam members 45, the cam 
members 45, the leaf springs 47, and the second retainer means 46 are 
moved toward the right correspondingly by the biasing force of the spring 
56 against the spring 55. Since the clutch release bearing 20 and the 
clutch release lever 26 are not in contact at this time, the rod 40, the 
clutch release bearing 20, and the fork 27 are urged leftwardly by the 
biasing force of the spring 54 until the clutch release bearing 20 engages 
with the clutch release lever 26. Thereafter, the second portions 53 of 
the cam members 45 are brought into contact with the second cam surfaces 
51 of the retainer 43 to thereby establish engagement between the racks 48 
of the cam members 45 and the racks 49 of the rod 40 against the outward 
force of the leaf springs 47. 
It will be apparent that the racks 48 re-engage with the racks 49 when cam 
members 45 are moved rightwardly relative to the rod 40 by a distance 
which is equal to the sum of the distance by which the cam members 45 are 
moved rightwardly by the spring 56 and the distance by which the rod 40 is 
leftwardly moved by the spring 54. After re-engagement, the rod 40, the 
cam members 45, the leaf springs 47, and the second retainer means 46 will 
move leftwardly together with the retainer 43 to effect clutch 
disengagement. 
When the clutch pedal 10 is released, the clutch release bearing 20, the 
fork 27, the rod 40, the cam members 45, the leaf springs 47, the 
retainers 46 and 43, the end wire 38, the wire 39 and the clutch pedal 10 
return toward their original positions. When the elements return to 
positions corresponding to the positions when the racks 48 of the cam 
members 45 are re-engaged with the racks 49 of the rod 40 during 
depression of the clutch pedal 10, there is no biasing force of the clutch 
release lever 26 being exerted on the clutch release bearing 20, the fork 
27, the rod 40, the cam members 45, the leaf springs 47, and the second 
retainer means 46. Since the retainer 43 continues to move rightwardly 
relative to the cam members 45, the racks 48 of the cam members 45 
disengage with the racks 49 of the rod 40. 
If the second retainer means 46 has not returned to its neutral position 
upon the above disengagement, the cam members 45, the leaf springs 47, and 
the second retainer means 46 follow the rightward return movement of the 
retainer 43 relative to the rod 40 because of the biasing force of the 
spring 56. Although the rightward movement of the cam members 45 is 
stopped when the second retainer means 46 reaches its neutral position, 
the retainer 43 still moves rightwardly under the biasing force of the 
return spring 12 and the wire cable 15 so that the first cam surfaces 50 
of the retainer 43 are brought into contact with the first portions 52 of 
the cam members 45 to establish engagement between the racks 49 of the cam 
members 45 and the racks 49 of the rod 40. Thereafter, cam members 45, the 
leaf springs 47, the second retainer means 46, and the rod 40 will move 
rightwardly together with the retainer 43 so that the clutch release 
bearing 20 is spaced from clutch release lever 26 by the predetermined 
distance. 
Referring now to another preferred embodiment shown in FIG. 3, the parts of 
the self-adjusting mechanism that are similar to those of the preferred 
embodiment of FIG. 2 are indicated by the same reference numerals. Since 
the operation of this embodiment is the same as the embodiment shown in 
FIG. 2, no further detailed explanation is made below. 
In this embodiment, the self-adjusting mechanism 16 further comprises third 
spring means for urging the wire cable 15 to a taut condition. Preferably, 
the third spring means has a spring 57 inserted between the end cable 37 
and the retainer 43. The spring 57 biases the retainer 43 toward the right 
so that the wire 39 of the wire cable 15 is always in its tense or pulled 
condition. The biasing force of the spring 57 thus maintains the retainer 
43 at a predetermined position to thereby assure the engagement between 
the retainer 43 and the cam members 45. This results in the second 
retainer means 46 being positioned at its desired predetermined position 
to ensure a proper self-adjusting function of the clutch assembly. 
It can be seen from the foregoing that the self-adjusting release mechanism 
minimizes an idle or accidental actuating stroke of the clutch pedal 10 
because the wire 39 is always in its taut or pulled condition. If the 
spring 57 is selected to have a considerably large biasing force, the 
arrangement of the return spring 12 of the actuating means 5 may be 
omitted. 
It can be further seen from the foregoing that the self-adjusting release 
mechanism is actuated by a relatively small manipulating or depression on 
the clutch pedal 10 and that the number of sliding engageable elements is 
minimized. 
It will be apparent to those skilled in the art that various modifications 
and variations could be made in the clutch assembly of the invention 
without departing from the scope or spirit of the invention.