Clutch brake noise suppressor

A clutch brake for use with non-synchronized vehicle transmissions includes noise suppression components. The clutch brake comprises a pair of housing members secured together which receive components of a torque limiting assembly. The assembly includes an inner ring member adapted to rotationally engage the transmission drive shaft and which is coupled to a concentric, outer ring member through a lost motion coupling. The outer ring, in turn, is frictionally coupled to the housing by an adjacent wave spring which includes inwardly directed tabs. The tabs exert a biasing force against the inner ring member, inhibiting wholly unrestricted motion which might generate undesirable vibration and noise.

BACKGROUND OF THE INVENTION 
This invention relates generally to friction clutches used in vehicles and 
more particularly to clutch brakes utilized in non-synchronized heavy-duty 
transmissions. Such brakes are activated upon disengagement of a main 
clutch to retard rotation of transmission gearing for easier gear 
shifting. 
It is well known in the art to retard vehicle transmission gears prior to 
gear shifting by using a clutch brake activated by the throw-out mechanism 
which disengages the main clutch. Torque limiting clutch brakes which 
provide a limited amount of braking torque are also well known, and are 
widely preferred because of their durability and long life. 
Resilient means have been used in torque limiting clutch brakes to cushion 
the braking effect and to prevent excessive braking pressure which may 
damage the clutch brake. For example, prior art devices have included 
opposed Belleville springs for establishing a predetermined frictional 
load between the inner and outer members of clutch brakes. Clutches 
utilizing opposed Belleville springs must be carefully designed and 
accurately assembled in order that one spring balances the other. An 
imbalance between the springs can cause one to overcome the other, 
reversing its concavity and interfering with the operation of and 
shortening the life of the clutch brake. 
SUMMARY OF THE INVENTION 
The present invention relates to a clutch brake for use with 
non-synchronized vehicle transmissions which includes noise suppression 
components. The clutch brake comprises a pair of generally circular 
housing members which are secured together and receive components of a 
torque limiting assembly. The torque limiting assembly includes an inner 
ring member having at least a pair of tabs or similar structures which are 
adapted to rotationally engage the transmission drive shaft. The inner 
ring member is coupled to a concentrically disposed outer ring member 
through a lost motion coupling. The outer ring is frictionally coupled to 
the housing by an axially adjacent wave spring which includes a pair of 
inwardly directed tabs. The tabs exert a biasing force against the inner 
ring member which inhibits wholly unrestricted motion that might generate 
undesirable vibration and noise. The outer surfaces of the housing include 
friction facing material. An alternate embodiment further includes a 
second wave spring disposed within the housing on the side of the outer 
ring opposite the first wave spring. 
Thus it is an object of the instant invention to provide a clutch brake 
having means to eliminate wholly unrestricted motion of the inner member 
of the torque limiting assembly of a clutch brake. 
It is a further object of the instant invention to provide a clutch brake 
having a single wave spring which includes inwardly directed tabs for 
engaging the inner ring member of the torque limiting assembly to inhibit 
wholly unrestricted motion thereof. 
Further objects and advantages of the present invention will become 
apparent by reference to the following description of the preferred and 
alternate embodiments and appended drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to FIG. 1, a clutch brake assembly according to the present 
invention is illustrated and generally designated by the reference numeral 
10. The clutch brake assembly 10 is illustrated in position on associated 
drive line components of a vehicle (not illustrated). Specifically, the 
clutch brake assembly 10 is disposed upon a drive shaft 12 which extends 
from a conventional pull-type friction clutch 14 to a non-synchronized 
vehicle transmission 16. The drive shaft 12 is rotatably supported by 
suitable bearings, typically anti-friction bearings (not illustrated) in 
the housings of the friction clutch 14 and transmission 16. The drive 
shaft 12 transfers power from the driven components of the clutch 14 when 
they are engaged to gear ratio selecting components within the 
transmission 16 according to conventional practice. Positioned 
intermediate the clutch brake assembly 10 and the housing of the friction 
clutch 14 and slidably disposed upon the drive shaft 12 is a clutch 
release bearing 18. The clutch release bearing 18 may be operated by a 
conventional clutch linkage 22 which disengages the friction clutch 14 by 
translating the release bearing 18 away from the housing of the friction 
clutch 14, toward the clutch brake assembly 10 according to conventional 
practice. 
Referring now to FIGS. 2, 3 and 4, the clutch brake assembly 10 defines a 
disc-like housing comprising a first circular housing member 26 having a 
radially extending peripheral shoulder 28 and a second circular housing 
member 30 having an axially extending peripheral lip 32. When assembled, 
the peripheral lip 32 is rolled over the peripheral shoulder 28 of the 
first housing member 26, thereby tightly and positively securing the two 
housing members together. The housing members 26 and 30 may, 
alternatively, be secured by welding, fasteners, or other suitable, 
similar means. Both housing members 26 and 30 define a centrally disposed 
aperture 34 which receives the drive shaft 28 and a plurality, preferably 
four, of smaller apertures 36 disposed adjacent each central aperture 34. 
As illustrated in FIG. 2, the smaller apertures 36 are arranged in axial 
alignment when the first housing member 26 and second housing member 30 
are assembled. The first housing member 26 also defines a pair of 
diametrically opposed rectangular openings 38, one of which is illustrated 
in FIG. 4. Finally, the housing members 26 and 30 both include organic 
friction facings 40 on their outer faces. The facings 40 may be bound to 
the housing members 26 and 30 in any of several ways, such as adhesive, 
well known in the art. The friction facings 40 are disposed for frictional 
engagement with adjacent surfaces on the release bearing 18 and housing of 
the transmission 16. 
Within the housing members 26 and 30 are the operative components of the 
clutch brake assembly 10. They include a first, inner annulus or ring 
member 42. The first ring member 42 preferably includes a pair of 
diametrically opposed lugs 44 which are received within and engage 
complementarily disposed channels 46 formed in the drive shaft 12. The 
lugs 44 thus rotationally couple the inner ring member 42 to the drive 
shaft 12 while permitting axially unrestricted motion relative thereto. 
Formed in the periphery of the inner ring member 42 are a second pair of 
diametrically opposed lugs 48. 
A second, outer annulus or ring member 50 is disposed concentrically about 
the inner ring member 42. The outer ring member 50 defines an inner 
marginal edge defining a plurality of slots, at least a pair of 
diametrically opposed slots 52 being generally complementarily to and 
receiving the lugs 48 on the inner ring member 42. The slots 52, however, 
are elongated, that is, longer than the circumferential length of the lugs 
48 and thus their alternate bi-directional engagement exhibits several 
angular degrees of lost motion. This lost motion or rotational free travel 
between the inner ring member 42 and the outer ring member 50 exists 
because the lugs 48 have a shorter circumferential length than the 
elongated slots 52. The outer ring member 50 is fabricated of powdered 
metal having appropriate frictional and heat sink characteristics. A 
preferred material is an oil based powdered metal, such as SN-0205, which 
facilitates slippage with the frictional members after a predetermined 
torque is reached. Other oil based materials such as special oil based 
steels as well as glass filled synthetic resin, for example, may also be 
used. 
The preferred embodiment clutch assembly 10 also includes a single axially 
resilient wave spring or wave washer 56. The wave washer 56 is preferably 
fabricated of steel which has been hard tempered to a Rockwell C hardness 
of between 40 and 48. The wave washer 56 defines four circumferentially 
equally spaced waves and provides a biasing force against the outer ring 
member 50 to maintain it in intimate, frictional engagement with the inner 
surface of the second housing member 30. The wave washer 56 includes a 
pair of diametrically opposed, radially outwardly projecting tabs 58. The 
tabs 58 register with the pair of diametrically opposed rectangular 
openings 38 in the first housing member 26 thereby rotationally securing 
these components together. The wave washer 56 further includes a pair of 
inwardly projecting lugs or tabs 60. The tabs 60 conform to the contour of 
the wave at their locations. The tabs 60 are disposed in parallel to one 
another and to a centrally disposed line or diameter and are equally 
spaced and laterally offset therefrom as illustrated in FIG. 4. The inner 
marginal edges of the tabs 60 conform to a circle but, since they are 
offset from radial or diametral lines, the end surface is obliquely 
curved. The tabs 60 extend inwardly and terminate approximately at the 
radial middle of the inner ring member 42 as illustrated in FIG. 2. As 
also noted in FIG. 2, the apertures 36 provide an open region adjacent 
each of the wave washer tabs 60 such that they may deform axially. The 
tabs 60 provide a biasing force against the inner ring member 42 which, in 
turn, biases it toward the second housing member 30. This biasing force 
and the resulting position of the inner ring member 42 inhibits wholly 
unrestricted free motion of the ring member 42 to an extent sufficient to 
preclude the generation of noise. The biasing force of the tabs 60 is of a 
magnitude small enough that it does not interfere with the rotational 
action of the lost motion coupling between the inner ring member 42 and 
the outer ring member 50. 
In operation, the clutch brake assembly 10 functions in a substantially 
conventional manner. That is, when the release bearing 18 is activated by 
the clutch linkage 22 and moved toward the clutch brake assembly 10, the 
friction facings 40 frictionally engage adjacent surfaces of the release 
bearing 18 and housing of the transmission 16 thereby restraining the 
housing members 26 and 30 of the clutch brake assembly 10. The wave washer 
56 which rotates with the housing members 26 and 30 provides a controlled 
frictional interconnection between it and the adjacent outer ring member 
50. The desired frictional coupling and torque transfer between the 
components of the clutch brake assembly 10 may be adjusted by the 
variation of conventional parameters such as spring thickness, wave 
height, surface material and finish, and the like. The outer ring member 
50 is rotationally coupled to the inner ring member through the lost 
motion coupling of the lugs 48 and elongated slots 52. Since the inner 
ring member 42 is rotationally coupled to the drive shaft 12 by the lugs 
44, the clutch brake assembly 10 slows the rotating elements of the 
transmission 16, thereby facilitating gear ratio selection. 
Referring now to FIG. 5, a first alternate embodiment 10' of the clutch 
brake assembly 10 is illustrated. The alternate embodiment clutch brake 
assembly 10' is substantially identical to the preferred embodiment of the 
clutch brake assembly 10 and thus comprises a first housing member 26 and 
a second housing member 30 which both include organic outer friction 
facings 40. Received within the housing members 26 and 30 is an inner ring 
member 42 and an outer ring member 50 rotationally coupled to the inner 
ring member 42 through a lost motion coupling consisting of lugs 48 which 
are received within elongated slots 52. A first wave washer 56 like that 
utilized in the first embodiment, that is, including inwardly directed 
tabs 60 is disposed to one side of the ring members 42 and 50. On the 
opposite side of the ring members 42 and 50 is disposed a second wave 
washer 62 which is the same in all respects as the first wave washer 56 
except that it does not include the inwardly projecting tabs 60. Thus, the 
second wave washer 62 functions only as a means to frictionally 
interconnect the outer ring member 50 with the adjacent inner surface of 
the second housing member 30. It neither contacts nor functions as a means 
of minimizing or eliminating unwanted axial motion and possible noise 
generation by the inner ring member 42. The alternate embodiment clutch 
brake assembly 10' is preferably utilized wherein drag and torque 
throughput requirements are greater than those provided by the preferred 
embodiment clutch brake assembly 10. 
The foregoing disclosure is the best mode devised by the inventor for 
practicing this invention. It is apparent, however, that apparatus 
incorporating modifications and variations will be obvious to one skilled 
in the art of clutch brakes. Inasmuch as the foregoing disclosure is 
intended to enable one skilled in the pertinent art to practice the 
instant invention, it should not be construed to be limited thereby but 
should be construed to include such aforementioned obvious variations and 
be limited only by the spirit and scope of the following claims.