Importance

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Abstract

The drum brake wheel cylinder (20) comprises a longitudinal through bore (16) having therein a pair of opposed pistons (22, 24) with each piston (22, 24) engaging a respective web (12, 14) of an adjacent drum brake shoe. A first piston (22) includes a longitudinal opening (32) receiving therein one end (62) of a friction rod (60), and the second piston (24) includes a recess opening (27) receiving therein the second end (64) of the friction rod. A friction latch adjusting lever (50) has a central opening (52) receiving therethrough the friction rod (60) and is located diagonally relative to a longitudinal axis of the friction rod (60). A spring (70) is located about the friction rod (60) with one end biasing the friction latch adjuster lever (50) against a wall (34) of the first piston (22) and the other end of the spring engaging an abutment (27B) in the recess opening (27 ). The first piston (22) includes a through opening (36) receiving slidably therein an adjuster release pin (40) which extends into a slot opening (56) of the friction latch adjusting lever (50). A running clearance (X) is defined between a head (66) at the second end (64) of the friction rod (60) and the abutment (27B) at the opening recess (27). Hydraulic pressure which displaces the pistons (22, 24) a distance greater than the running clearance (X) causes the friction rod (60) to be displaced relative to the friction latch adjusting lever (50) which effects an adjusted at-rest position of the pistons (22, 24) in accordance with drum brake shoe lining wear.

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First Claim