Interface - The Journal of Wheel/Rail Interaction

FRICTION CONTROL

Controlling Top-of-Rail Friction
August 28, 2004

Friction control has been shown to produce significant benefits over the years. Effective gauge-face and top-of-rail (TOR) friction control can reduce energy consumption by 7% - 25% and lateral curving forces by 25% - 50%. Proper management can also reduce wheel/rail wear.

Overall, these benefits can add up to significant savings. North American railroads spend about $3.6 billion per year in fuel costs, tie and fastener maintenance, rail and wheel wear, and derailments. "An effective friction management program that addresses these areas can reduce overall costs by 5% - 20% and produce annual savings of $240 million," Rich Reiff, principle engineer at the Transportation Technology Center, Inc., told delegates at Advanced Rail Management / Interface Journal's 2004 Rail/Wheel Interface Seminar. "In order to achieve these savings, however, the application method must be reliable and the cost of the products and maintenance must be less than the projected savings."

Friction control includes the use of grease-based lubricants and water-borne friction modifiers. Though they are often used together, there are fundamental differences between them. Traditionally, lubrication has been applied to the gauge face of the rail and wheel flanges to reduce friction to 0.25µ or less. Greases tend to migrate from the gauge face to the top of the rail, however. While this is sometimes beneficial, it usually is detrimental, negatively affecting truck steering and train braking.

Unlike grease, TOR friction modifiers control friction levels at 0.3µ to 0.35µ. Very little of this material, which is applied by wayside, hi-rail or locomotive-mounted applicators, migrates from the top of rail to the gauge face. Traditional gauge-face lubrication is generally used along with the TOR material in sharp curves. While the primary benefit of TOR lubrication is a reduction in curving forces, it can also reduce wear and energy requirements.

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