Patent ID: 8487214

Claim:
A welding carriage for supporting at least one welding machine relative to a workpiece having substantially linear first and second lateral sides and a joint to be welded, the welding carriage comprising: a first lateral support having at least one first wheel assembly; a second lateral support having at least one second wheel assembly; a four-bar leading parallelogram linkage and a four-bar trailing parallelogram linkage, each of the leading and trailing parallelogram linkages comprising first and second parallelogram linkages, each having an upper bar and a lower bar parallel to each other, each parallelogram linkage pivotally connected to each other at inner ends at a common fulcrum point and pivitally connected at outer ends to their respective first and second lateral supports, first and second actuation linkages, the first actuation linkage pivotally connecting to the first parallelogram linkage at a first drive point intermediate along its length and to an intermediate and common actuation point, and the second actuation linkage pivotally connecting to the second parallelogram linkage at a second drive point intermediate along its length and to the common actuation point, an actuator connected between the common fulcrum point and the common actuation point for driving the first and second parallelogram linkages together and apart for adjusting a lateral spacing between the first and second lateral supports, wherein the leading parallelogram linkage and the trailing parallelogram linkage form a frame for supporting the at least one welding machine; and the at least one first and the at least second wheel assemblies support the frame for movement upon the workpiece and guide the frame relative to the first and second lateral sides and along a path substantially parallel to the first and second lateral sides.