| 摘要 |
1,204,625. Internal shoe-drum brakes; bearings. DEUTSCHE PERROT-BREMSE G.m.b.H. 26 Feb., 1968 [27 Feb., 1967], No. 9200/68. Headings F2A and F2E. In a wedge-operated internal shoe-drum brake adapted to be actuated by fluid-pressure in a cylinder 2a or, alternatively, by a spring accumulator (not shown) or by means of a linkage system, a wedge expander 3 is actuated to spread apart thrust members 6 which engage the brake shoes and balls 8 are interposed between the thrust members and the wedge expander in order to reduce friction. The balls 8 are guided in running grooves 13a, 13 disposed both in the wedge expander 3 and in the thrust members 6 respectively, the cross-section of each running groove being formed by two curved surfaces 13<SP>1</SP>, 13<SP>11</SP>, 13a<SP>1</SP>, 13a<SP>11</SP> which extend to a medium intersection 13b each curve having a radius r<SP>1</SP> which is larger than the radius of curvature r of the curvature of the ball so as to bear against the thrust member 6 and the wedge expander 3 in the manner shown in Fig. 2. The balls 8 are guided in a cage 9 which is loosely retained on the wedge expander by means of two noses 10 (Fig. 3) to prevent the ball 8 from dropping out. |
