Multi-body dynamics analysis for the wear of front-rod bearing during the switching operation of railroad switches (Effect of adjustment condition)

Abstract

Since the wear of front-rod bearings of railroad switches induce the switch failure, wear evaluation is indispensable. On the other hand, the various parts of railroad switches are adjusted so as to avoid derailment. For example, the attachment position of the adjustment nut of switch adjuster rod could enlarge the contact force between tongue rail and stock rail. The extension of front rod is also used to eliminate the gap between the toe of tongue rail and stock rail. In this paper, the bearing wear during the switching operation is estimated by multi-body dynamics simulation. The effects of the attachment position of adjustment nut and the extension of front rod are also evaluated. When the switch moves rightward, the driving force of electric point machine is transmitted to switch rod through switch adjuster rod. Then, the force is transmitted to right tongue rail through right switch rod bracket which connects switch rod and right tongue rail. Although the attachment position of adjustment nut controls the contact force between tongue rail and stock rail, that does not change the path of force transmission and the force acting on the bearing. Therefore, the attachment position does not affect the bearing wear. On the other hand, the extension of front rod changes the path of force transmission. The most of driving force of electric point machine is transmitted to the left switch rod bracket, front rod and right tongue rail in order. Therefore, the increase in the force acting on the bearing increases its wear. In the case of 6 mm extension of front rod, the estimated amount of wear is 3.44 μm, which is 3 times larger than the case of no extension.