Cylinder with two-stage movement, especially a welding cylinder

Claim 1

In a cylinder with two-stage movement, in which a first piston which seals against the inside of a housing is axially displaceable in the housing, and in which a second piston, arranged coaxially with the first piston, seals in an axial cavity in one end of the first piston, is axially displaceable in said cavity and carries a piston rod which slides sealingly through one housing end which faces the cavity in the first piston, and in which in the other housing end there is arranged a pressure medium inlet tube which extends through the first piston and into the piston rod, via which tube pressure medium can be brought into or out of a first chamber delimited by the first and the second pistons, and in which second and third chambers in the housing, on the sides of the first and second pistons that face away from each other, have pressure medium connections; the improvement comprising, on the side of the second piston facing away from the piston rod, a tubular, axially oriented guide member which is sealingly guided in the first piston and slides on the inlet tube and seals against the outside of the tube and extends through the first piston, the inlet tube, at its end facing away from the guide member, being movably mounted in said other housing end.