Wheel – Rail Interface: Forgotten Influences

Aug 7, 2018 1:50:18 PM

The interface between rollingstock wheels and the track railhead is central in terms of maintenance, replacement cost and downtime reduction, energy and environmental management and the operational safety and integrity of the railroad operations. This small but extremely crucial contact area is where the wheel meets the rail, however; this interaction plays an integral part in the whole lifecycle costs of both assets.

The ideal profiles of the wheel, the rail, and their combined interaction are a science within their own rights and vary depending on the operation. There are some simple tasks however that the respective maintainers can undertake to ensure optimal performance and results of both pieces of infrastructure.

The interdependence of poor decisions affecting both rail and wheel is crucial to the overall cost to the business. A wheel with a defect such as a flat or rolling contact fatigue, for example, has significant implications due to increased forces on and between rail and sleeper, and damage can occur to both track and rollingstock over long distances depending on what controls and detection have been put in place. Similarly, poor rail welds, broken rails, faulty rail greasers, and incorrect rail profile can severely affect the rollingstock integrity.

So while both maintainers carry out their duties with the best of intentions, what can go wrong when one of the crucial parameters out in the field is changed and how can that change affect the peak performance of the network?

Whilst there are various detection and monitoring systems for rollingstock available and often in place, there are times when an unpredicted spike in wheel wear has the maintainer scrambling to determine what has changed. What has caused wheels to suddenly present with an increase in wear rates, and therefore a need to change wheels out for turning or replacement?

Two crucial aspects of the network optimization that are often forgotten are the re-profiling of new rail and the reinstatement of rail greasers. A lack of understanding of purpose can quickly throw out the balance of the fundamentals of wheel/rail contact mechanics, wear, fatigue and lubrication as wheel wear rates climb considerably in a short period greatly affecting rollingstock performance and dynamics.

Often rail is replaced with all of the best intentions, however, re-profiling the head is planned for another day. Rail lubricators are run dry or not reinstated. Having an all-round working knowledge of the rail network, and a planning team that provides regular communication and updates on performance with all Stakeholders at the ground level is critical for any business. This allows business units to make decisions and carry out planned maintenance activity based on what is not only best for their needs but also takes into account other business units and ultimately undertake an action that is best for the whole of business.