Abstract: The invention provides a piston formed by casting a metal piston body under pressure around an insert, the body being made of aluminium or aluminium alloy and the insert being made of a porous layer having a thickness 20 to 50 times the pore diameter and completely filled with the piston body metal which projects from the body into the pores of the insert.

Abstract: A light-metal piston with parts hard-eloxated to increase their resistance to heat and mechanically reinforced to the depth of the hard eloxation.

Abstract: In a liquid-cooled cylinder sleeve for combustion engines of the reciprocating piston type, the provision of a cylinder wall thickness which increases in a rotationally symmetrical manner along its periphery in the direction of the line of intersection of the piston pivoting plane passing through the longitudinal axis of the cylinder and the wall of the cylinder sleeve.

Abstract: Welding method and apparatus for detecting the penetration depth of an electron beam weld, in which X-rays which occur are guided through several plates of an absorption device to a ray receiver, the plates comprising of plurality of bores of equal diameter, which are arranged in their position to one another in such a way that the center lines of corresponding bores on the same level are in exact alignment and that the ray receiver, absorption device and workpiece are aligned in parallel with one another and are co-ordinated to one another in height.