Brakes – Wheel – Transversely movable
Reexamination Certificate
2000-03-30
2001-11-20
Schwartz, Christopher P. (Department: 3613)
Brakes
Wheel
Transversely movable
Reexamination Certificate
active
06318515
ABSTRACT:
TECHNICAL FIELD
This invention relates to a hold down spring for yieldably securing a drum brake shoe to a drum brake backing plate.
BACKGROUND OF THE INVENTION
Drum brake shoes are secured to a drum brake backing plate by drum brake hold down springs, which secure the brake shoes to the backing plate while allowing for movement of the brake shoes relative to the backing plate when a brake application is effected. Hold down springs include a nail which extends through apertures in the backing plate and the brake shoe, a coil spring circumscribing the nail, and a spring retainer slidable on the nail. The spring extends between the brake shoe web and the retainer. The hold down spring must be assembled when the brake is assembled, which requires substantial manual dexterity of the assembler, because of the relative small size and relative complexity of the various components of the drum brake.
One hold down spring design is disclosed in U.S. Pat. No. 5,368,139, which discloses a hold down spring in which the spring retainer is assembled onto the nail by first forcing the retainer downwardly over the nail so that the enlarged end of the nail is received in a wider portion of an opening in the retainer as the spring is compressed, and then moving the retainer laterally to seat the nail in a narrower portion of the opening. The lateral movement of the retainer requires manual dexterity, and it is difficult to determine if the nail is properly seated.
SUMMARY OF THE INVENTION
According to the invention, the retainer of a drum brake hold down spring is provided with a slot having a wider portion through which the expanded end of the nail is received and a narrower portion defining a seating area for the nail. A narrower inclined portion of the slot extends between the wider portion and the abutment surface. Accordingly, once the nail is received within any part of the narrower section of the inclined portion of the slot after having been installed through the wider portion of the slot and released, the action of the spring tends to force the nail along the inclined portion of the slot and into seating area. An improperly installed retainer is obvious, since if the nail is not received within the narrower inclined portion of the slot the spring will push the retainer off of the nail, and once the nail is received within the narrower inclined portion of the slot the nail will be urged into the proper seating area.
REFERENCES:
patent: 5368139 (1994-11-01), Pirrallo
patent: 5836429 (1998-11-01), McGuire
Bartz C. T.
Delphi Technologies Inc.
Schwartz Christopher P.
Sigler Robert M.
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