4. Operating principle of the electric welder

An electric welder (figure 3 ) is a machine consisting of a fixed head holding one rail end and a moving head holding the other rail end, which moves back and forth to perform the welding process.

This machine supplies the rail ends with the electrical energy needed to bring them up to surface melting temperature, using electrodes placed at the head and base (figures 3 , 4 and 5 ).

A first light spark ensures that the ends are squared and slightly pointed...