Special workbench for positioning and preassembly of overhead line system

The utility model belongs to the field of factory preassembly of high-speed railway overhead line systems, and particularly relates to a special workbench for positioning and preassembly of an overhead line system. The special workbench solves the problems that an overhead line system positioning device is not high in preassembly precision and surface twisting easily happens to a positioning support. The special workbench comprises a preassembly supporting frame, a positioning pipe lug ring fixing clamp, a lengthening rotary arm and a rotatable fixed supporting seat. The preassembly supporting frame comprises inverted-T-shaped fixed supports symmetrically arranged on the two sides. A connection rod is connected between the inverted-T-shaped fixed supports on the two sides. The positioning pipe lug ring fixing clamp comprises lug ring fixing double lugs and a rotary shaft, wherein the rotary shaft is connected with the fixed support on one side in a welded mode, and the lug ring fixing double lugs are welded t