University of Salford - Articles and news items
Issue 1 2012 / 6 February 2012 /
The contact between wheels and track is fundamental to railway operations, but the contact conditions are affected by often unpredictable external sources of contamination such as fallen tree leaves, snow and rain which can substantially reduce the level of adhesion of the track that is essential to the delivery of tractive effort for traction and braking systems in railway vehicles. The problem of low adhesion reduces the traction and causes wheel spin when trains accelerate or lock their wheels to slow down which can potentially cause severe wear of wheel and rail surfaces, increase mechanical stress in the system and affect stability.
The history of adhesion management can be traced back to the use of sanding systems in locomotives to improve adhesion as early as the late 19th century, but there have since been significant advances in wheel slip/slide protection (WSP) technologies for braking and traction systems. The most commonly used wheel slip protection schemes are achieved by measuring and controlling the slip ratio (relative speed between a wheel and the train) and in more extreme cases to control the wheel rotational acceleration below a pre-defined threshold. Further performance enhancement may be obtained with the use of hybrid anti-slip approaches with the use of slip, wheel speed and acceleration information. Those controllers are difficult to obtain optimal performance and also require accurate measurement of wheel slip. In general, WSPs are effectively reactive systems, i.e. only ‘activated’ to stop wheel slip/slide when detected by the sensors.
Rail industry news / 14 September 2011 /
Research at the University of Salford is on track to solve the age-old problem of leaves on the line delaying trains…