Abstract
Keywords: Hydraulic-Actuator, Control System, Overturning, Vehicle Stability, pivoting system
The aim of this paper is to propose an approach to overcome the problem of overturning on a rail track turn.
Whenever a train starts negotiating a turn, a centrifugal force starts acting on it. Generally a train will overturn when the overturning moments become greater than the righting moments. While encountering a turn, the centre of sprung mass shifts outboard of the trains centre line and this contributes a destabilizing moment that reduces the stability. A load transfer takes place from the inner wheels to the outer wheels. The amount of load transfer depends upon the centrifugal force, the height of the centre of gravity and the wheel track. Lowering the centre of gravity will decrease the load transfer. Hence centre of gravity should be kept as low as possible. But this can be done only up to a certain limit. Widening the track will decrease the load transfer. But the track is usually set by the rules or aerodynamic considerations.
Records prove that only a minority of overturning accidents could have been avoided with a warning device, potentially more with a skilled driver, but half of the accidents are not preventable by driver action alone. This highlights the need for an active safety system on the vehicle.
In this paper, a single train compartment has been considered for analysis. Based on the vehicle tilting theory, a mechanism has been proposed which tilts the vehicle body towards the inner direction of the track turn while negotiating a turn. Moreover, mathematical formulations have been done and it has been shown in the paper that the stability can be increased considerably by the proposed mechanism. Overturning accidents are of special concern for passenger safety. This paper takes an in-depth look at the mechanics and contributing features to identify prevention strategies