| 摘要 |
A hydraulic wheel brake cylinder (12) and the housing (22) of an intermediate support (20) are secured to a base plate (10) at diametrically opposed positions. Two brake shoes (16, 18) are supported by their ends opposite to the wheel brake cylinder (12) on the intermediate support (20). In addition, a mechanical actuator (50-58) is arranged near the wheel brake cylinder (12). The wheel brake cylinder (12) and the intermediate support (20) are arranged in such a way that when the brake is hydraulically actuated during forward motion both brake shoes (16, 18) act as secondary shoes. A guide (24) at least approximately parallel to the wheel brake cylinder (12) and a stop (26) are formed on the housing (22) of the intermediate support (20). An adjusting element (28) is capable of limited axial displacement in the guide (24). One of the brake shoes (16) is supported on an end of a push pin (34) which, when the brake is hydraulically actuated, can be moved by a force (c) that acts on its second end in the direction of said brake shoe (16). The push pin (34) is linked in a non self-blocking way with the adjusting element (28) in relation to this force, but in a self-blocking way in the opposite direction. When hydraulically actuated, the brake presents a degressive characteristic curve, but a progressive characteristic curve when it is mechanically actuated. |
