In daily life, the biggest moving object that most people may encounter may be a train. Watching a train rolling on the track, it’s hard not to be moved by the huge power, which may be a mile long hopper car carrying millions of tons of goods.
But this is the other side of the coin – the engineering department needs to control the train and finally stop it – this is the theme of this gem in the British transportation film the power of parking. On the surface, stopping the train is not entirely high-tech; In the 100 years before the film was made in 1979, the technology of pressing cast iron brake shoes on the wheels remained basically unchanged. Interestingly, the metallurgy of brake iron has a great impact on braking efficiency and safety. Considering that British Railways used about 3.5 million brake shoes a year at that time, anything that could make them last longer could bring considerable savings.
However, it is the safety of railway brakes that urges people to study how to improve them. British Railway’s research department noticed that cast iron is fragile, easy to wear quickly and easy to produce a large number of dangerous sparks. Therefore, the phosphorus content in cast iron was studied to find the best mixture suitable for this work. They turned to a brake dynamometer with amazing energy. The results showed that increasing the content of trace elements can greatly reduce wear and sparks, and shorten the braking time.
Although we all think about safety, we have to admit that some chicken tail sparks caused by low phosphorus shoes are very spectacular. Nevertheless, it is interesting to see how much thought and energy we spend on optimizing such a seemingly simple thing. Next time you watch a train pass, think about this.