Can you grease a squeaky wheel and still stop a train?:Performing contrasting functions simultaneously is just one of the challenges with railroad track lubrication:Performing contrasting functions simultaneously is just one of the challenges with railroad track lubrication:Performing contrasting functions simultaneously is just one of the challenges with railroad track lubrication

摘要

Trains traverse the land, weaving disparate communities into a single fabric. Ubiquitous, their presence is usually marked by their metal wheels clacking along metal tracks. On long, straight, flat rails, metal meeting metal moves the train along at a constant speed easily and safely. But come upon a curve, a hill or the end of the line and circumstances change. A curve needs slip, a hill needs traction, trains must stop.