A welding assembly (1) for welding two rails (2) of a track includes two rail clamping units (5) movable towards one another in an assembly longitudinal direction (4). A power rail (10) provided for power transmission is configured as an assembly guide (3), extending in an assembly longitudinal direction (4), which is spaced from displacement drives (11) and connects both rail clamping units (5) to one another. The power rail (10) is equipped with a cooling device and displaceable in the assembly longitudinal direction (4) relative to the rail clamping unit (5) equipped with the power rail contacts (8).