| 摘要 |
PURPOSE:To prevent adjustment of shoe clearance, which follows the deformation of a brake drum, from becoming excessive, by providing an adjusting gear screwed in a piston put in a cylinder chamber and a sub-gear in a space connected to said cylinder chamber, said sub-gear meshing with said adjusting gear. CONSTITUTION:When a shoe clearance increases due to the wear of a brake shoe, a piston 2 moves to recover determined shoe clearance. After that, an adjusting gear 3 rotates to make said piston 2 move on a male screw 3a' because a sub-gear 10 is not rotatable due to a clutch spring 12, the movement causing the brake shoe to rub the drum to generate braking force. While, when said piston 2 moves forewards following the deformation of the drum in braking, the shaft 3a of said adjusting gear 3 can not rotate because the axial force to said shaft 3a is large, and so both gears 3 and 10 move forewards together, said sub-gear 10 compressing a cone spring 11. Due to the above construction, the adjustment of shoe clearance is prevented from becoming excessive.
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