Abstract: A steel material is useful for producing the upper part of engine pistons with high wear, corrosion and heat resistance. This steel has the following composition (in % by weight): 1.20 to 150 Mn; 0.50 to 0.80 Si; 0.35 to 0.40 C; 0.10 to 0.50 Mo; 0.08 to 0.13 V; 0.010 to 0.065 S; 0.015 to 0.050 Al; .ltoreq.0.035 P, the remainder being iron and production impurities.

Abstract: An aluminum axle journal or wheel mount comprises an aluminum body to which a bearing unit is secured. A steel pivot is inserted into the aluminum body which supports the wheel bearing unit and which is braced against the aluminum body. The aluminum body can be either cast or forged and after it has been produced is designed with a dimensionally accurate opening that serves to receive the steel pivot. After pressing in the steel pivot, a wheel bearing unit is fitted onto the steel pivot and secured against axial shifting using a suitable attachment, preferably a necked-down bolt.

Abstract: An electrode mounting plate having a flat face adhesively bonded to a graphite electrode and an opposite face forming a trough with reinforcing ribs, the trough being covered in use by the mounting plate of the spark machining apparatus to define a chamber communicating with the dielectric circulation system of the apparatus. Flow passages for the dielectric fluid are formed by drilling holes through the mounted electrode and the flat face of the electrode mounting plate.