Abstract: A cam operated rail clamping device comprising: a base; a vertically disposed post projecting upwardly from the base and secured thereto; a tube rotatably and slidably mounted on the post; a hydraulically operated lift cylinder for raising the tube; a vertically disposed beam extending upwardly from the base and secured thereto; a horizontally disposed flange secured to the lower end of the tube; a clamping jaw carried by the flange and provided with a plurality of teeth for engagement with one side of a rail; a wearing shoe carried by the base for engagement with the other side of the rail; the flange being mounted for rotation about the post to bring the high point of the jaw into wedging action with the rail when the flange engages the top of the rail; and, a set of microswitches for cam positioning.