Brakes – Position adjusters – Supports
Reexamination Certificate
1999-06-16
2001-05-29
Butler, Douglas C. (Department: 3613)
Brakes
Position adjusters
Supports
C188S329000, C188S330000, C188S332000
Reexamination Certificate
active
06237732
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to a boot for a cam braking system bushing assembly and more particularly to a boot that snaps in place.
Bushing assemblies are used to support a camshaft in a brake housing. As known, the brake camshaft drives a brake cam to actuate the brake. A secondary purpose of the bushing assembly is to allow for lubrication of the camshaft so that it can freely rotate.
Known cam bushing assemblies include a bushing retainer having an aperture and a bushing disposed within the aperture. The bushing retainer is removably attached to the brake housing and the bushing is removably attached to the retainer. This design allows for more efficient lubrication flow around the camshaft.
Boot assemblies have been used in combination with spherical bushing retainers. The purpose of the boot is to keep dirt and other contaminants away from the bushing environment. However, the design of the boot used with spherical bushing retainers are not very effective at preventing contaminants from entering the bushing assembly environment because the boot is not secured to the bushing assembly. Further, the boot does not act as a secondary sealing system. Lubrication could leak around the boot because the boot is not connected to the retainer.
An ineffective boot design allows dirt and debris within the bushing environment. The introduction of debris into the bushing environment contributes to increased wear of the bushing components and the camshaft. Increased wear of the components translates into frequent maintenance, high repair costs, and decreased life expectancy of all cam braking system components.
SUMMARY OF THE INVENTION
The cam bushing boot assembly of the present invention overcomes the above problems with known cam bushing boot assemblies. In general terms, the disclosed boot assembly covers and protects a bushing assembly in a cam braking system by snapping in place over the bushing retainer. The boot assembly directly connects to the bushing assembly by preferably snapping over the bushing assembly. Further, the boot assembly can be used with any type of cam brake bushing assembly, including, but not limited to, cam bushing assemblies and spherical ball design bushing assemblies.
The primary purpose of the boot assembly is to provide a shield to minimize intrusion of debris and other contaminants around the camshaft support bushing and its associated seals. Dirt and contaminants cause damage to the bushing, its seals and ultimately the camshaft, thereby increasing the amount of required maintenance of those parts and the frequency of replacement. Therefore, it is desirable to minimize the amount of contaminants introduced to the bushing environment. The boot serves this purpose. Use of the boot decreases the wear of the bushing and the seals, therefore, increasing the useful life of bushing components and the camshaft.
Additionally, the boot assembly acts as a secondary sealing system that supplements the primary sealing system. In other words, the boot helps contain the lubrication within the bushing assembly.
These and other features of the invention may be best understood from the following specification and drawings. The following is a brief description of the drawings.
REFERENCES:
patent: 4540072 (1985-09-01), Suzuki et al.
patent: 4890939 (1990-01-01), Koschinat
patent: 5788340 (1998-08-01), Kobyashi
patent: 2321677 (1998-08-01), None
DeLeeuw William L.
Pfister David K.
Butler Douglas C.
Carlson & Gaskey & Olds
Meritor Heavy Vehicle Systems LLC
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