PISTON FOR A MASTER CYLINDER

摘要

A plastic piston of master cylinder has a first member having a small diameter portion and a second member having a large bore portion. Excess welding resin is prevented from being leaked into a seal ring mounting groove formed on a part of the outer peripheral surface of the small diameter portion by provision of welding portions in the form of a space defined between an outer peripheral surface of the small diameter portion of the first member and the large bore portion of the second member, and a gap defined between a tip end of the small diameter portion of the first member and the bottom of the large bore portion, the space and gap being provided respectively for preventing the excess welding resin from being leaked into the seal ring mounting groove. The plastic piston has no parting lines along the seal ring mounting groove which results in achieving a superior seal effect.