Self adjusting drum brake - has shoe locating strut which also forms pivot for wear adjustment bell crank

摘要

Two drum brake shoes (2, 3) are held apart in the unoperated condition by an adjustable-length strut (10) located between the former, and whose length can be altered by rotating a pinion (14). One end of the strut (10) forms a pivot (20) about which a bell crank (15) can rotate. On operation if wear is excessive, a pin (27) on one shoe (3) will strike the side of an oversize hole (26) in the bell crank (15), rotating it. A catch (23) on its other arm (17) will engage the pinion (14), lengthening the strut (10), thus reducing the clearance between shoes (2, 3) and drum.