| 摘要 |
A pair of brake shoes (36) arranged opposite one another are intended for engaging the side faces of a rim (F) and are each fastened to the end region of an arm (30, 31) of a brake caliper (29). The arms (30, 31) are jointly pivotable, counter to the effect of a restoring spring (47), in a plane at a right angle to the direction of frictional force, and moreover the brake shoes are displaceable to a restricted extent in a direction at a right angle to the pivoting plane. The arms (30, 31) interact with a sloping face (23, 24), in order, during the displacement of the brake shoes (36), to be pressed against the corresponding side face of the rim (F) in an assisted manner. To reduce the danger that the arms (30, 31) will jam during the application of the brake and that consequently the braked wheel (11) will lock, the end regions of the two arms (30, 31) are each supported on a sloping face (23, 24) via a freely rotatable roller (51), these sloping faces (23 24) converging in the direction of frictional force and are anchored firmly to the bicycle frame (12, 13). The arms (30, 31) are each pivotable about their own pivot pin (33, 34'), and the sloping faces (23, 24) and rollers (51) are arranged between the respective brake shoe (36) and the pivot pin (33, 34').
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