Scissor support for welding tank sections

Abstract

A support and lift assembly for welded tank courses is provided outboard of a three ring cage used to internally circumferentially weld adjacent tank courses. The support and lift assembly is used to move the welded tank courses into position for another course to be welded on. A tank course conveyor extends longitudinally outboard of the cage. The conveyor is discontinuous at one or more positions and a scissors support and lift assembly is located at such discontinuous positions. A piston is pivotably connected to one of the arms which extends generally horizontally into a cylinder pivotably connected to the other arm. A roller course support is rotatably mounted at the end of each arm to support welded tank courses. A second piston extends vertically between the base and one of the arms and extends into a second cylinder extending vertically and connected to the other of the base and the arm. A first vertical height limit switch is located on the upper surface of a jack in the center ring. Another vertical height limit switch is located on a jack in the nearest end ring of the cage. Fluid pressure applied to the horizontal cylinder controlled by these limit switches displaces the piston head and moves the arms and respective rollers vertically to raise a tank course until aligned with the limit switches. A lateral stability limit switch is located on either the horizontal cylinder or piston which controls the flow of fluid to the vertical cylinder to control lateral stability.