Overhead welder travels assembly line

This portable spot welder has halved the time and the number of operations necessary for assembling B-26 bomb-bay doors by the Glenn L. Martin Company. The skin, frames, and stiffeners for the doors are assembled in a fixture to be tack-welded with the portable spot welder and the entire assembly then is carried to a floor-type spot welder. The portable welder consists of a spot weld machine and transformer counterbalanced on a small beam pivoting from an overhead trolley which travels along a 50-foot I beam. The trolley is propelled by sprocket and chain powered by a one-third-horsepower electric motor. A 200-kva welding machine with a capacity of two thicknesses of 0.040-inch aluminum is used.