Mohammad Ali Rezvani - Assistant Professor, School of Railway Engineering
Amin Mazraeh - MSc Student,School of Railway Engineering, Iran University of Science and Technology

Three piece bogies are widely in use by the freight railway services throughout the world. In comparison with the other freight bogies they cost less and are easier to maintain. However, they do not exhibit favorable curving behavior. Amongst the methods to improve the bogie performance is the proposal to introduce clearances in the bogies axleboxs. In the case of the three piece bogies, the clearances have been used by some of the practicing engineers. Itobviously added to the non-linear effects in the bogie tribological system and its dynamic performance. This study includes simulating the effects of the axlebox longitudinal clearances on hunting and curving behavior of the three pieces bogies. The effects of lubricating the rails at curves and adding to the track gauge are also investigated. The simulation is with the Universal Mechanism (UM) engineering software. It involves a loaded freight wagon equippedwith two three piece bogies of type 18-100. Propositions are made in order to improve the vehicle dynamic performance and to decrease its maintenance costs.

axlebox clearance, vehicle longitudinal stability, three piece bogie (18-100), coefficient of friction, wheel/rail friction work, rail lubrication, added track gauge