Friction modifier application to railroad tracks

铁路在铁轨上使用各种摩擦改进剂。一些摩擦改进剂将轮轨之间的摩擦降低到一个低的中间值，从而提高燃油经济性，减少车轮磨损和车轮尖叫。这些摩擦改进剂通常作为液体使用。其他摩擦改进剂可以增强列车车轮和轨道之间的摩擦，以改善在湿滑条件下的断裂和牵引力。在这些应用中，摩擦改进剂通常是颗粒状固体，如沙子。这里提出的研究将着眼于液体和固体摩擦改进剂在铁路轨道上的应用。

Railroads apply various friction modifiers to railroad tracks. Some friction modifiers reduce the friction between the wheel and rail to a low-intermediate value, which improves fuel economy and reduces wheel wear and wheel squeal. These friction modifiers are normally applied as liquids. Other friction modifiers enhance the friction between the train wheel and the rail, to improve breaking and traction in slippery conditions. In these applications the friction modifier is usually a granular solid such as sand. The research proposed here will look at the application of liquid and solid friction modifiers to railroad tracks. One way to apply liquid friction modifier to tracks is to ooze the liquid onto the tracks from a stationary supply, and then have the train wheels pick up liquid from the puddle of friction modifier. The research will study how wheels pick up liquid from a puddle, and how that liquid is subsequently carried far downstream on the tracks (so called "carry down"). The researchers will also study how the liquid properties affect liquid "carry down", with the goal of recommending alternative liquid formulations to improve "carry down". Granular solids are normally conveyed to the tracks from train-mounted sanders that blow sand onto the tracks upstream of train wheels. Any sand dispensed by the sander that does not make it to the wheel-rail nip is wasted. The researchers will study rail sanding in a laboratory setting by creating a sander, wheel, and rail system that simulate a full-scale sander. The trajectory of sand particles issuing from the sander, and the fraction of the sand that lands into the nip between the wheel and rail, will be measured. A novel (non-sand) granular material will also be studied, to understand how its different bounce characteristics will affect the fraction of material entering the wheel-rail nip. Based on these measurements the operation of the sander and the characteristics of the sand particles will be optimized, minimizing the amount of product that is wasted.