Abstract: In accordance with the disclosure, the workpieces being welded are brought together by rectilinearly oscillating at least one of them along the line of bringing them together with the amplitude in the movement of the workpiece towards the other workpiece greater than that in the movement of the same workpiece in the direction opposite to the direction towards the other workpiece, voltage is applied to said workpieces for flashing and heating them in the course of bringing them together, and then an upset force is applied to the workpieces. The hydraulic drive adapted to generate the oscillatory rectilinear motion in a continuous flash butt-welding machine includes a hydraulic cylinder with two chambers which provides for moving one of the workpieces being welded with respect to the other and comprises apparatus for feeding hydraulic fluid alternately into either of the chambers of the hydraulic cylinder of the machine, the apparatus being connected with the cylinder through two hydraulic lines.

Abstract: The base of the apparatus has the form of a claw clamp with two grips for gripping a rail that are kinematically linked with a clamping cylinder. The apparatus incorporates an upper cutter and side cutters, mounted so that, with the claw clamp closed, the cutting edges of the cutters form an outline embracing the cross-sectional perimeter of the rail. Each side cutter is hinged to the respective grip and mounted thereon for a displacement parallel to the axis of symmetry of the outline formed by the cutting edges of the cutters. The upper cutter is kinematically linked with the rod of the clamping cylinder via a clearance take-up mechanism which provides for lifting the upper cutter and the side cutters hinged thereto to engage the side cutters with the rail foot underside.