Abstract: A machine for flash-butt welding of rails, incorporates two tong-type clamping devices made in the form of two two-arm levers carried by a common central axle with insulation from each other and capable of being displaced along the axle relative to each other by two flashing-upsetting hydraulic cylinders connecting them and having bimetal current-carrying rods. Each of the two-arm levers is hinged at one end to the rod or the clamping hydraulic cylinder case, respectively, and the other end is fitted with the clamping and current-carrying jaws. Two welding transformers built into the hollow two-arm levers of one of the two tong-type clamps are joined by current-carrying jumpers through the current-carrying part of the rods of the flashing-upsetting hydraulic cylinders to the current-carrying clamping jaws. A clamping hydraulic cylinder is made with a hydraulic intensifier built into its rod.