Seal unit for brake booster

摘要

A seal unit is provided for a brake booster such as of a tandem type which includes a center plate within its shell. The brake booster includes annular means disposed within the shell for maintaining a hermetic seal between the center plate and a valve body. An axial portion of the center plate is formed with an axially extending cylindrical portion, the end of which is folded radially inward to define a U-shaped fold. The annular seal means is fitted inside the cylindrical portion, with its part disposed between the inner peripheral surface of the cylindrical portion and the outer peripheral surface of the fold. This effectively prevents the annular seal means from being withdrawn from the center plate.