PISTON OF WHEEL CYLINDER FOR DRUM BRAKE

摘要

PROBLEM TO BE SOLVED: To enlarge an abutting range of a brake shoe without enlarging a diametrical size of an engaging head part. SOLUTION: An engaging head part 45 of a piston projecting from a cylinder body is provided with a pair of projecting parts 58 projecting toward an outer peripheral side corresponding to an engaging groove 52 where a shoe web 16a (18a) is fitted, and an abutting surface 58a continuing to a groove bottom 52a of the engaging groove 52 is formed in the projecting part 58 so as to make the shoe web 16a (18a) abut on the abutting surface 58a. The projecting part 58 is provided at a part spaced at a specified dimension toward the engaging groove 52 side from an end surface 46a for forming an annular groove to position a cylinder boot, and the spacing dimension and a projection dimension of the projecting part 58 are determined so as not to damage the cylinder boot by interfering with the projecting part 58.