Brakes – Wheel – Axially movable brake element or housing therefor
Patent
1992-07-08
1993-11-02
Le, Mark T.
Brakes
Wheel
Axially movable brake element or housing therefor
188 725, 188250B, F16D 5500
Patent
active
052576795
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to the support of brake shoes in a spot-type disc brake and to the associated brake shoes. A spot-type disc brake of the type with which the present invention is related is shown in German Published Patent Application DE-OS No. 38 33 553. In this type of brake it is possible to remove the brake shoes radially outwards from an open, radially extending cavity of the brake housing, without the brake housing having to be dismantled or swung out of position. The circumferential forces ensuing upon a brake application are transmitted by the brake shoes to axial brake housing projections provided with plane supporting surfaces which face the cavity in the circumferential direction and whereon the brake shoes rest. Holding pins are provided in order to secure the brake shoes against being displaced in the radial direction, the holding pins axially extending across the radially outer area of the cavity and being detachably fastened on the brake housing. The pad carrier plates of the brake shoes have projections with openings for receiving the holding pins. A spring detachably fastened in the area of the holding pins presses the brake shoes radially against the holding pins so as to prevent the brake shoes from rattling. The spring and the holding pins have to be removed for the purpose of removing the brake shoes.
This known spot-type disc brake has the disadvantage that in manufacturing the brake housing, considerable relatively complicated milling work has to be performed when machining the above-mentioned plane supporting surfaces for the brake shoes. The guideway and the fastening device of the brake shoes on the holding pins likewise require a considerable amount of manufacturing and assembling operations.
In another spot-type disc brake known from German published Patent Application DE-OS No. 14 75 288, supporting surfaces of circular arc shape are provided for the brake shoes, these surfaces not being milled but rather turned together with the cylinder bores of the four brake cylinders. The brake shoes are supported on the supporting surfaces both in the radial in the and circumferential directions. This solution, however, has the disadvantage that it is impossible to remove the brake shoes radially outwards. It is necessary to dismantle the brake housing for the purpose of replacing the brake shoes which causes additional assembly operations and costs incurred thereby. It is an object of this invention to provide a spot-type disc brake where the brake shoe supporting surfaces destined for receiving the circumferential forces can be turned together with the bore of the brake cylinder but where it is possible to radially remove the brake shoes through a radially outwards open brake housing cavity.
SUMMARY OF THE INVENTION
The solution of this object results when the supporting surfaces are formed on short height projections and have a radiused shape having a slightly larger radius than that of the brake cylinder, but coaxial with the brake cylinder axis. This arrangement permits the supporting surfaces to be bored or turned together with the brake cylinder bore in one operation by means of a stepped tool having different radii in different axial areas. This results in an advantageous elimination of the separate milling operation of the supporting surfaces and of the manufacturing cost incurred thereby.
At the same time, the radiused supporting surfaces in accordance with this invention are substantially centered on a line passing through the center of the brake center and normal to the brake disc radius, and have a short radial height, with a limited radial dimension, minimized so as to allow the brake shoes to be removed radially through the cavity. This lowers the cost of assembly and maintenance.
The short height supporting surfaces have the further advantage of reducing susceptibility to corrosion of the brake shoe holding device.
It is possible to eliminate the holding pins for the brake shoes if further supporting surfaces are provided on the brake
REFERENCES:
patent: 4392559 (1983-07-01), Oshima
patent: 4394891 (1983-07-01), Oshima
Bach Uwe
Panek C. Peter
Weiler Rolf
Alfred Teves GmbH
Le Mark T.
Lewis J. Gordon
Seitter Robert P.
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