| 摘要 |
The invention relates to a floating, mechanically operated expansion device for an overrun-braked internal-expanding-shoe brake with automatic return by means of brake shoes held touching the brake plate by springs, the expansion device comprising two main parts, that is a bell crank lever and a bell crank housing. In this, a bowden cable, acting on one arm of the bell crank lever, actuates the expansion device, so that bell crank lever and bell crank housing expand the brake shoes. Known expansion devices of this type have the disadvantage that they require an adjusting device which also has to be actuated for adjustment of the brake, especially for the parking brake. The object is to improve the expansion travel ratios so that adjustment of the brake system is performed exclusively on the basis of modified ratios on the service brake. According to the invention, this is achieved in that, when the parking brake is actuated, the bell crank lever achieves an additional expansion travel, in which it is supported in an elongated hole as soon as the bell crank lever, by way of the curved piece fitted to it, rests on a stop fitted in the bell crank housing. <IMAGE>
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