The Operating Procedure of the Device Enhancing the Wheel-Rail Adhesion

The results of the analysis of sand application efficiency for improving wheel-rail adhesion are presented. An algorithm for the sandbox operation is substantiated, based on supplying sand under the wheels when their slip reaches a critical level, delivering sand in proportion to the vehicle speed, and automatically purging the sand supply pipes. The principle of sandbox operation is based on the mechanical interaction between the moving elements and sand. It has been established that the maximum adhesion coefficient is achieved when the sand is evenly distributed in a single layer within the wheel-rail contact area. The important role of the contact area in the wheel-rail adhesion is emphasized. A sandbox implementing the developed sand supply algorithm is proposed. The introduction of this sandbox on Ukrainian-manufactured trams is described.