Abstract: A piston rod has a hollow section with an open end, a housing, and a fastening connection for a piston. The housing includes a cap welded to the open end, a tubular intermediate piece welded to the cap, and a bottom part attached to the fastening connection. The cap has a shoulder received in the intermediate piece to form an annular space which functions as a labyrinth seal to receive any weld spatters formed during the friction welding process. The outside surface of the piston rod is machined to final dimensions and surface coated following welding.

Abstract: A piston rod has a hollow piston rod section, a housing axially spaced from the end portion of the hollow piston rod, and a cup located between the end portion of the rod section and the housing and welded to the latter.

Abstract: To enable prescribed functional values of pressure plate units of motor vehicle friction clutches to be observed with smaller tolerances than hitherto, it is proposed that a housing-spring component initially be pre-assembled from clutch housing (1) and diaphragm spring (7) and that this component be measured together with a master pressing plate. Geometry (diameter 25 and axial height 27) which is optimum for minimum tolerances of a contact bevel 15 is calculated by means of the measured result, and a pressing plate (13) with this bevel geometry is produced. The measured spring-housing component is finally assembled together with this specially produced pressing palte 913).