pistons, piston manufacturing processes and a piston cylinder unit comprising these pistons and a door-closing unit and its manufacturing processes;

摘要

A piston for a door closer comprises metal cups (12, 13) on opposite ends of a stem (11). A plastics ring (17) is a snap-fit in one of the cups and protrudes from that cup to seal against the wall of a cylinder (23). A groove (21) in the side wall of the cup for receiving a rib (22) on the ring is formed by pressing a substantially flat blank before the blank is formed into the cup. IMAGE