| 摘要 |
The invention relates to internal shoe drum brakes having an automatic adjuster to maintain a substantially constant clearance between the brake shoes and the drum, when the brakes are released. A strut having a variable overall effective length acts between the shoes for automatic adjustment of the clearance and has one end portion connected to one brake shoe through a lost motion device. The lost motion device comprises a main lost motion connection for providing a minimum clearance and a secondary lost motion connection which provides a greater clearance for de-adjusting the brake, and a first spring acts to ensure that for normal service conditions the lost motion device acts through the main connection and the bias of this spring is overcome by manual operative device before the secondary connection becomes operable.
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