A Freight Train Suspension System

Abstract

From O’Connor and Luo (2014), a freight train suspension system will be presented for all possible types of motion. The suspension system includes a wedge system and a bolster system. The suspension system experiences impacts and friction between wedges and bolster. The impacts cause the chatter motions between wedges and bolster, and the friction cause the stick and non-stick motions between wedges and bolster. Due to the wedge effect, the suspension system may become stuck and not move, which causes the suspension to lose function. To discuss such phenomena in the freight train suspension systems, the theory of discontinuous dynamical systems will be used, and the motion mechanism of impacting chatter with stick and stuck will be discussed. The analytical conditions for the onset and vanishing of stick motions between the wedges and bolster will be presented, and the condition for maintaining stick motion will be obtained as well. The analytical conditions for stuck motion will be developed for the onset and vanishing conditions for stuck motion. Analytical prediction of periodic motions relative to impacting chatter with stick and stuck motions in train suspension will be performed through the mapping dynamics. Numerical simulations will be completed for illustration of periodic motions of stick and stuck motions. Finally, from field testing data, the effects of wedge angle on the motions of the suspension will be presented to find a more desirable suspension response for design.