Friction modifier application to railroad tracks

铁路将各种摩擦修改器应用于铁路轨道。一些摩擦改进剂将车轮和轨道之间的摩擦降低到低中间值，这提高了燃料经济性并减少了车轮磨损和车轮啸叫。这些摩擦改进剂通常以液体形式施用。其他摩擦改进剂增强火车车轮和铁轨之间的摩擦，以改善在湿滑条件下的制动和牵引力。在这些应用中，摩擦改进剂通常是粒状固体，例如砂。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。将液体摩擦改进剂施加到轨道的一种方式是将液体从固定供应源渗出到轨道上，然后使火车轮从摩擦改进剂的水坑中拾取液体。该研究将研究车轮如何从水坑中拾取液体，以及液体如何随后在轨道上被带到下游（所谓的“向下携带”）。研究人员还将研究液体性质如何影响液体“携带”，目的是推荐替代液体配方以改善“携带”。颗粒状固体通常从安装在火车上的砂磨机输送到轨道，该砂磨机将沙子吹到火车车轮上游的轨道上。任何砂分配的砂，没有使它的轮轨压区是浪费。研究人员将在实验室环境中通过创建模拟全尺寸砂光机的砂光机，车轮和轨道系统来研究铁路砂光机。将测量从砂光机发出的砂粒的轨迹，以及落在车轮和轨道之间的辊隙中的砂粒的分数。还将研究一种新的（非砂）颗粒材料，以了解其不同的反弹特性将如何影响进入轮轨夹持部的材料的分数。基于这些测量结果，砂光机的操作和砂粒的特性将得到优化，从而最大限度地减少浪费的产品量。

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.