SERVO DEVICE FOR FRICTION ENGAGING APPARATUS

摘要

PURPOSE:To relieve concentration of stress thus to prevent shifting of piston by making a notch for preventing shift at the position symmetrical with the notch section around the central axis of cup-shaped piston having a notch at a portion of cylindrical section. CONSTITUTION:A notch section 34 for passing a pole is made at the position of cylindrical section 27 of an outer piston 23 in servo apparatus 22 for brake 18 corresponding with a parking lock pole 17 such that the pole 17 will approach to the outer tooth 16 for lock gear of a ring gear 5 positioned at the inside of cylindrical section 27 and engage. Since a notch 35 of same shape is made at the symmetrical position around the central axis with said notch, concentration of stress on the piston is prevented resulting in prevension of shifting.