Principal Investigator/Researcher

Dr. Andrew Peterson, Virginia Tech

Project Description

The proposed project will continue the efforts that have been underway at (RTL) for the past couple of years for designing and implementing various devices for reliably and reasonably accurately measuring the presence of top-of-rail (ToR) friction modifiers. Such materials are used by railroads to manage the coefficient of friction at the wheel-rail interface. The main challenge in measuring the presence and extent of TOR friction modifiers is that they are applied in very thin layers, commonly a few microns. The material is such that it cannot be easily detected with the naked eye, and is very difficult to measure using tactile or non-tactile means. RTL has developed a laser-based technology that allows measuring the presence of material, qualitatively, on the rail. The qualitative measurements are aimed at establishing index-based methods that can help the railroads with an assessment of the presence of TOR on their rail, beyond the empirical methods currently available to them.

The tactile sensor that is under development in this project promises to provide the means for quantifying the thickness of TOR friction modifiers on the rail in an automated and simple-to-use device. The device takes advantage of the conductivity of lubricants that are used in practice to integrate a gear-driven micrometer with a motor that advances the tip until an electrical circuit is closed. This indicates the top of the lubrication layer. The tip is advanced further until it reaches the top of the rail, which prevents it from moving any farther. This signifies the bottom of the lubricant. The difference between the two measurements—commonly in 2 – 20 microns—indicates the thickness of the lubricant layer at the specific location of the measurement.

A prototype unit has been tested in the laboratory under different rail conditions and on various types of rail, including a 40-ft rail panel. The results have been quite promising, even though some additional work remains with improving the device’s electro-mechanical design for ease of operation and measurement.