Abstract: Self-equalizing welding structure and method. The structure comprises piston and cylinder structure held in a fixed support, including cylinder ends movable into and out of the opposite ends thereof, a welding electrode attached to one rod cylinder end on one side of a workpiece, a travel rod extending through the support and connected to the other cylinder end, means for securing a second electrode to the travel rod on the other side of the workpiece, and self-equalizing pressure means for extending the cylinder ends from the piston and cylinder structure and for withdrawing them into the piston and cylinder structure.