| 摘要 |
A drum brake of the inner shoe type has a self-adjusting device which comprises a push rod, one end of which cooperates with a first brake shoe, while the other end cooperates with a second brake shoe with the intermediary of an adjusting wedge, the position of which determines the effective length of the push rod. In the released state of the brake, the brake shoes abut the push rod-and-wedge assembly, whereby an air gap is defined between the brake lining and the drum. A clamping spring urges the push rod and the second brake shoe against the one and the other wedge flank. The wedge angle of the adjusting wedge is so selected that normally no shifting of the wedge occurs. The push rod has an abutting and displacing arrangement which-as soon as the brake shoe travel exceeds, during brake actuation, a basic structurally determined desired air gap-shifts the push rod against the force of the clamping spring and thus loosens the wedge. As a result, the wedge is advanced to a corresponding extent, thus increasing the effective length of the push rod-and-wedge assembly.
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