PISTON AND DISC BRAKE USING SAME

摘要

A piston is provided with: a cylindrical wall section (52) having an opening (51) at one axial end thereof; and a bottom section (53) closing the other axial end of the wall section (52). The bottom section (53) has: an annular first region (71) provided on the inside radially of the wall section (52) so as to be continuous with the wall section (52); and a second region (72) provided on the inside radially of the first region (71) and formed so as to be recessed axially. The second region (72) has a changing-thickness region (103) having an axial thickness reduced toward the inside radially.