Positioning pin setting arrangement

A setting pin assembly is disclosed for properly positioning a positioning pin in a two disc clutch. In one embodiment, the setting pin assembly is slidably received in an aperture in a clutch cover, with the aperture being coaxial to the positioning pin. The setting pin preferably has enlarge portions at each axial end of the clutch cover. The enlarged portion on the inner end of the setting pin transmits force to the positioning pin over a relatively great surface area. A spring is preferably mounted between the clutch cover and the enlarged portion at the outer end of the setting pin, to normally bias the setting pin outwardly of the clutch cover and force the enlarged portion on the inner end of the clutch cover against the aperture. The setting pin extends outwardly of the clutch cover, and by merely contacting the setting pin with a hammer or similar tool the positioning pin may be moved to a proper position.

BACKGROUND OF THE INVENTION 
This application relates to a clutch having two driven discs. More 
particularly, the present invention relates to an assembly for properly 
positioning an intermediate plate relative to the two driven discs. 
Clutches having a pair of driven discs with an intermediate plate dipsosed 
between the discs are known. A flywheel is disposed at one end of the two 
dics and is fixed to a clutch cover at the other end of the two discs to 
enclose the clutch. Rotational velocity is selectively transmitted from 
the flywheel to drive the discs. 
The intermediate plate between the two discs must be accurately positioned 
to provide proper clearance between the discs and the intermediate plate. 
Several prior art systems have developed various arrangements to properly 
position this intermediate plate. In one system, a plurality of 
positioning pins slidably mounts the intermediate plate between the two 
discs. The positioning pins and intermediate plate move a small distance 
with clutch engagement towards the flywheel. When the clutch is disengaged 
the intermediate plate and positioning pin move the same small distance 
away from the flywheel. The intermediate plate will typically be 
frictionally engaged on the positioning pin such that it may move along 
the positioning pin towards the flywheel to compensate for wear on the 
discs. 
In initially positioning the intermediate plate, the clutch is engaged and 
the positioning pins are forced into contact with the flywheel and move 
relative to the intermediate plate. With the clutch engaged, the 
intermediate plate is in the proper position for clutch engagement. Thus, 
the intermediate plate is positioned on the positioning pins in the proper 
clutch engaged position whenever the positioning pins are in contact with 
the flywheel. Once the clutch has been initially set up, the positioning 
pins provide a stop for movement of the intermediate plate against the 
flywheel which defines the proper clutch engage position. The clutch cover 
typically provides a stop for the clutch disengaged position. 
Problems have arisen in these prior art clutches since the clutch cover 
blocks access to the positioning pins making it difficult to initially 
position them relative to the flywheel. In response to this problem some 
prior art clutches have provided an aperture through the cover for each 
positioning pin, and some member is inserted through this aperture to 
contact the positioning pin and force it against the flywheel. Typically, 
a set pin is inserted through the aperture in the cover and is hit with a 
hammer or similar tool to move the positioning pin to a desired position. 
Such a system is disclosed in U.S. Pat. No. 4,601,373. 
While the above-described prior art clutch does overcome some problems, 
there are still deficiencies in the clutch. First, a set pin inserted 
through the aperture to contact the positioning pin and force it against 
the flywheel, may not be directed along an axis coaxial to the positioning 
pin. Thus, the force transmitted to the positioning pin could be skewed 
off the axis of the positioning pin. The positioning pin may bind within 
the intermediate plate, and result in some misalignment. Further, these 
prior art systems require close work to initially position the 
intermediate plate since the set pin must be inserted into each of the 
apertures individually to ensure proper placement of the positioning pins. 
In the prior art, the aperture through the cover could not be coaxial with 
the positioning pin since the cover provides a stop for the positioning 
pin in the disengaged position. Movement of the positioning pin to the 
clutch disengaged position might cause it to move into the aperture, which 
would be undesirable. As an alternative, it was suggested that the 
aperture be made of a smaller diameter than the diameter of the 
positioning pin. These two requirements resulted in a problem with some 
prior art systems wherein the force transmitted to the positioning pin was 
directed along an axis that was not coaxial to the axis of the positioning 
pin, and was also over a relatively small surface area. 
It is an object of the present invention to overcome the above-discussed 
limitations in the prior art clutches. 
SUMMARY OF THE INVENTION 
In a disclosed embodiment of the present invention, an intermediate plate 
mounted on a positioning pin is disposed between a pair of driven discs. 
The positioning pin positions the intermediate plate relative to the two 
discs. A cover encloses the discs, intermediate plate and positioning pins 
to enclose the clutch assembly. Access apertures are formed through the 
cover to allow access to the positioning pins from outside of the cover. 
In a preferred embodiment of the present invention, the access apertures 
slidably receive a setting pin which extends outwardly of the cover. The 
setting pin may be hit by a hammer or similar tool to move against the 
positioning pin and properly position the positioning pin relative to the 
intermediate plate. Preferably, the positioning pins abut a flywheel to 
define the proper position for the positioning pin. 
In a most preferred embodiment of the present invention, there are a 
plurality of such positioning pins and setting pins. Further, in a most 
preferred embodiment of the present invention, each setting pin is spring 
biased outwardly of the apertures in the cover. Even more preferably, each 
setting pin has a pair of enlarged portions spaced on each axial side of 
the aperture in the cover such that the setting pin will not move 
outwardly of the cover. The setting pin enlarged portion on the inside of 
the cover provides a stop to prevent pin movement outwardly of the 
aperture. The enlarged portion on the outside of the cover prevents the 
setting pin from being moved too far into the clutch and in addition, 
provides a shoulder for the spring which biases the setting pin outwardly 
of the clutch cover. Most preferably, the spring is a conical spring. 
In disclosed embodiments of the present invention, the aperture in the 
clutch cover may be a cylindrical aperture or, alternatively a notch 
formed at the outer periphery of the cover. 
With the disclosed setting pin assembly, a force transmitted to the setting 
pin will be transmitted along the axis of the positioning pin. The setting 
pin is properly guided within the aperture and moves along the proper axis 
to contact and move the positioning pin. Also, the force is transmitted 
from the enlarged portion on the inside end of the setting pin, and is 
thus over a relatively large area. Further, since a portion of setting pin 
preferably extends outwardly of the clutch cover, an operator merely needs 
to contact the setting pin and force it into the clutch cover to properly 
position the positioning pin. It is not necessary to insert a set pin into 
each hole in the clutch cover for each of the several positioning pin. 
These and other objects of the present invention can be best understood 
from the following specification and drawings of which the following is a 
brief description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 illustrates clutch assembly 20 having flywheel 22, intermediate 
plate 24 and a pair of driven discs 26 and 28. A clutch cover 30 is fixed 
to flywheel 22 and encloses clutch 20. Positioning pins 32 frictionally 
mount intermediate plate 24 to properly position the intermediate plate 
relative to discs 26 and 28. Although one positioning pin 32 is 
illustrated, it should be understood that several are preferably utilized. 
In one preferred embodiment four such positioning pins are utilized. The 
function of the disclosed clutch is well known in the art and will be not 
further described here. Positioning pins 32 are preferably spring pins or 
split pins, which are a known type of pin having a central spring biasing 
its outer periphery radially outwardly. In this known type of pin, the 
outer free diameter of the pin is greater than the inner diameter of the 
hole in the intermediate plate that the pin passes through. As such, the 
plate is normally frictionally engaged at a particular point on the pin. 
Intermediate plate 24 is frictionally received on positioning pin 32 such 
that positioning pin 32 normally retains it in a desired location. In a 
clutch engaged position, positioning pin 32 abuts flywheel 22 to define a 
stop to properly position intermediate plate 24. Upon disengagement, 
intermediate plate 24 and positioning pins 32 move through a small 
distance to the right as shown in this figure, and positioning pin 32 
abuts a surface of cover 30. Should discs 26 and 28 wear to the point that 
intermediate plate must slide relative to positioning pin 32 to engage the 
clutch, intermediate plate 24 remains at its new position on positioning 
pin 32. This allows intermediate plate 24 to compensate for wear on discs 
26 and 28. Such frictional engagement and wear compensation is known in 
the art. 
In initially setting up clutch assembly 20, the clutch is engaged. In this 
position, intermediate plate 24 is accurately positioned relative to discs 
26 and 28. Positioning pins 32 are then positioned in contact with 
flywheel 22. With wear on discs 26 and 28, intermediate plate 24 may slide 
relative to positioning pin 32. Even so, positioning pin 32 will still 
contact with flywheel 22 to define the proper clutch engaged position. 
As shown in FIG. 2, positioning pin 32 is in contact with flywheel 22 and 
frictionally receives intermediate plate 24. Aperture 34 extends through 
cover 30 to allow access to the interior of clutch 20 such that 
positioning pin 32 can be properly positioned relative to intermediate 
plate 24. 
As shown in FIG. 3, aperture 34 may be slightly off-set of positioning pin 
32. In this way, positioning pin 32 is accessible from outside of cover 30 
while at the same time, aperture 34 does not interfere with movement of 
positioning pin 32. This structure is somewhat like the prior art clutches 
described above. 
An alternative embodiment that forms a portion of the present invention is 
illustrated in FIG. 4. As shown in FIG. 4, notch 36 replaces cylindrical 
aperture 34. 
Setting pin assembly 37 is illustrated in FIG. 5 and includes setting pin 
38 received within cylindrical aperture 34. Enlarged portion 40 rests 
against an interior face of clutch cover 30 while second enlarged portion 
42 is formed at a position outside of clutch cover 30. Conical spring 44 
is received between enlarged portion 42 and an outer face of clutch cover 
30. 
Conical spring 44 forces setting pin 38 outwardly of clutch cover 30. 
Enlarged portion 40 prevents setting pin 38 from moving outwardly of 
aperture 34. When it is desired to position positioning pin 32, the clutch 
is engaged such that intermediate plate 24 is gripped by discs 26 and 28. 
One then hits setting pin 38 with a hammer or similar tool and forces it 
inwardly to contact positioning pin 32. This contact causes positioning 
pin 32 to move relative to intermediate plate 24. Positioning pin 32 may 
preferably be forced against flywheel 22. 
Once positioning pin 32 has been properly positioned, the hammer, of 
course, no longer contacts setting pin 38, which is biased outwardly of 
cover 30. Since setting pin 38 remains in aperture 34, aperture 34 may be 
relatively large and also coaxial with positioning pin 32. Enlarged 
portion 40 covers aperture 34 such that the aperture will not interfere 
with movement of positioning pin 32 to the clutch disengaged position. 
In the prior art systems, aperture 34 was either off-set from the axis of 
positioning pin 32, or of a smaller diameter than positioning pin 32, such 
that it did not interfere with the movement of pin 32. This is somewhat 
undesirable since it makes it difficult to transmit a force to positioning 
pin 32 that is coaxial and over a relatively large surface area. 
With the arrangement illustrated in FIG. 5, setting pin 38 transmits a 
force to positioning pin 32 over the relatively large surface area of 
enlarged portion 40. Further since setting pin 38 remains in aperture 34, 
closing the aperture, it is possible to have setting pin 38 be coaxial to 
positioning pin 32 to ensure that the force transmitted to positioning pin 
32 is along the proper axis. 
A preferred embodiment of the present invention has been disclosed, 
however, a worker of ordinary skill within the art would recognize that 
certain modifications would come within the scope of this invention. For 
this reason, the following claims should be studied in order to determine 
the true scope and content of the present invention.