To the Issue of Axial Force Control in Threaded Joints, Mainly in Rail Fastenings to Railroad Sleeper Pads

Method of attaching rails to railway sleeper pads and devices to implement the method refers to the field of mechanization of railway transport and can be used in the assembly, repair and maintenance of railroad track. The purpose of the study is to develop a method of attaching the rail to sleeper pads, which would guarantee the standard rail-to-sleeper pads pressure with minimal variation of its nominal value. The method of applying a vertical load to the nut of the terminal bolt and, therefore, to its stem in two stages makes it possible to apply a vertical force at the first stage that is less than the required and, to start screwing the nut with minimum resistance in the thread and complete absence of end resistance of the nut relative to the spring washer. Applying at the second stage to the nut, and therefore to the terminal bolt, a vertical load corresponding to the required force of pressing the rail to the pad, allows at the beginning of the stage to screw the nut with minimum friction in the thread, and at the end of the stage to stop screwing the nut when the torque corresponding to the applied force is reached, determined, for example, by the increasing current in the current relay. The technical result of the research is to ensure the required standard effort to clamp the rail to the pad with a minimum variation of their value due to a simple and reliable control of the achieved effort by the torque corresponding to it.