192 clutches and power-stop control – Elements – Shafts – bearings – and adjusting devices
Reexamination Certificate
1999-12-10
2001-09-11
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Elements
Shafts, bearings, and adjusting devices
C192S111400
Reexamination Certificate
active
06286651
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to clutches and, more particularly, to improved adjusting rings used in clutches.
In order to transmit drive from an engine-driven flywheel to an output shaft, many clutches utilize levers for selectively urging driving and driven disks into contact with one another. The levers have first ends pivoted on a release sleeve and second ends pivoted on a clutch cover which rotates with the flywheel. Intermediate the ends of each lever are abutment surfaces which urge a pressure plate against the discs to effect frictional coupling of the discs. As the discs wear, the clutch will begin to slip if the position of the levers is not adjusted to compensate for the wear.
The adjustment is commonly accomplished by an adjusting ring having an externally threaded surface which is threadably coupled to an internally threaded surface of the clutch cover. By rotating the adjusting ring so as to axially advance it with respect to the clutch cover and the drive train, the second ends of the levers may be advanced so as to maintain proper pressure between the abutting surfaces of the levers and the pressure plate.
When the clutch is disengaged, the clutch adjusting ring is subject to substantial vibrations from the engine, especially in heavy truck applications. These heavy vibrations cause significant wear on the adjusting ring, and may even cause the ring to jump its threads. This, in turn, results in a loss of clutch adjustment and typically requires replacement of the adjusting ring.
Devices and methods to compensate for thread wear are well known. In one method, a seal is placed by, or around, the circumference of the threads to retain them in their proper position. These seals, however, frequently create an excessive amount of friction in the clutch, often causing the clutch to seize. Alternatively, means for locking the adjusting ring to the clutch cover may be used. However, this results in the loss of clutch adjustment once the driving and driven disks begin to wear. Additional methods include splitting the adjusting ring, sizing it to compensate for the thread wear, and then welding it back together. The splitting method, however, often produces an out-of-round ring which causes vibration or even driveline damage and clutch failure under load.
Therefore, it would be advantageous to have an inexpensive and efficient method to secure the adjusting ring to the clutch cover to withstand the vibrations of the engine, reduce or eliminate threadwear, and preserve the ability of the ring to provide clutch adjustment.
SUMMARY OF THE INVENTION
The invention is a clutch adjusting ring designed to reduce, or eliminate, threadwear by providing a more secure engagement between the externally threaded surface of the ring and the internally threaded surface of the clutch cover. Although the ring and clutch cover threaded surfaces are securely engaged, the invention allows the clutch to be readily adjusted to compensate for wear on the drive and driven disks.
In a preferred embodiment, the invention comprises a clutch adjusting ring having a plurality of plugs seated within bores formed within the externally threaded surface of the ring. Preferably, three cylindrical plugs are fit into bores spaced equally about the circumference of the ring. The plugs are located between the first and last threads of the threaded surface of the ring.
The plugs may preferably be formed of temperature resistant nylon, and have a slightly greater outer diameter than the diameter of the bores to ensure a tight frictional fit. The end of the plugs preferably extend slightly radially outward beyond the outer diameter of the threads of the ring.
With the plugs located within the adjusting ring, the ring is threaded into cover. As the threads of the adjusting ring advance into the cover, the corresponding threads in the cover cut through the radially extending plugs located in the threads of the ring. The plugs frictionally grip the threads of the cover, thereby preventing, or greatly reducing, the amount of “play” in the adjusting ring, yet allowing the ring to be readily turned manually.
In one alternate embodiment, the plurality of plugs are located similarly within bores formed in the internally threaded surface of the clutch cover. In yet another alternate embodiment, one or more plugs may be located within both the internally threaded surface of the clutch cover and the externally threaded surface of the clutch adjusting ring. While ease of manufacture may suggest use of the first embodiment of the invention, these embodiments will also effectively prevent, or greatly reduce, the amount of “play” between the clutch cover and the adjusting ring.
The resulting clutch adjusting ring is capable of withstanding the vibrations of the engine, reducing or eliminating threadwear, and preserving the ability of the ring to provide clutch adjustment.
REFERENCES:
patent: 2462603 (1949-02-01), Boots
patent: 4760906 (1988-08-01), Flotow et al.
patent: 5213185 (1993-05-01), Flotow
patent: 5263564 (1993-11-01), Flotow
patent: 5456345 (1995-10-01), Bissett
Gears, Jr. Joe E.
Glessmer Laurence Lee
Mazziotti Philip J.
Lorence Richard M.
Marshall & Melhorn LLC
PMX Inc.
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