Curving Behavior of a Locomotive with Forced Steering Three-Axle Trucks

Abstract

The speed-up on railway tends to require higher powered and heavier locomotives, thus two three-axle trucks or three two-axle ones are needed for the heavy locomotive to meet the limitation to axle load. Here, it is beneficial for heavy locomotives to employ forced steering trucks to reduce the lateral force between the wheel and rail during curve negotiation. This paper deals with numerical analysis about curving behaivor and running stability of the forced steering three-axle trucks. In the analysis, wheel lateral forces and the critical speed for stable running are examined parametrically varying leverage ratio and stiffness in the steering link, wheel tread conicity and wheelset supporting stiffness. In addition, the possibility for improving the critical speed is investigated. The results show that the proper value for the leverage ratio changes with curve radius, and that higher leverage ratio can make the running stability worse under large steering link stiffness. It is also shown that the proper tuning of the wheelset supporting stiffness increases the critical speed keeping the lower lateral force brought by the forced steering mechanism.