two slidable carriages of identical construction are slidably mounted in a welding device side by side and move alternately 180 degrees out of phase with each other in a linear reciprocating movement . pivotal gripping plates are mounted on the slidable carriages which alternately clamp on selected gaps between flux coating sections of the welding electrode to advance it continuously towards the work piece . crank shafts are incorporated in the welding device to produce the linear reciprocating movement of the two slidable carriages , and cam wheels and pivotal bars are provided to locate alternately one group of gripping plates in the closed position to carry the welding electrode forward while the other group of gripping plates are in the opened position to facilitate the welding electrode to advance .