Wheeltapper

A wheeltapper is a railway worker employed to check the structural integrity of train wheels and that axle boxes are not overheating.

Typically employed at large urban railway stations and in goods yards, they tap wheels with a long-handled hammer and listen to the sound made to determine the integrity of the wheel; cracked wheels, like cracked bells, do not sound the same as their intact counterparts (they do not "ring true").

Wheeltappers also check that the axle boxes are not too hot by using the back of their hand.

Although wheeltappers still operate in some eastern European countries, in countries with modern planned maintenance procedures and line-side defect detectors, such as hot box detectors, wheeltappers are redundant. The job is mostly associated with the steam age. Wheeltappers were vital to the smooth running of the railways as a cracked wheel or overheated axle bearing would lead to delays and the loss of revenue. These were particularly common in the 19th century, when axle bearings were lubricated by grease. At this time, metallurgy was a more haphazard science and thus it was impossible to test steel wheels for cracks: the role of the wheeltapper was of crucial importance.

Anecdote
There is an anecdote of a wheeltapper who had worked diligently for years wheeltapping without ever questioning or understanding the purpose. This originated with Rudyard Kipling in Delhi, and is referenced in his work "Captains Courageous" of 1897,  although it had spread to the United States by 1932. "... A young friend of mine told me the other day about some experiments he had been making with steel rails. By means of electricity it is now possible to examine rails for flaws before they are laid, and thus greatly to reduce the chance of serious accident on account of hidden defects. What is now being done with rails will soon be done with structural steel and all metal which goes into service where not only strength, but lasting strength is required., - I remember in my childhood that when a train came into a station a man who had been waiting there with a hammer in his hand walked along the platform and tapped each wheel flange,' to ascertain whether or not there were any cracks in the wheel. ... That was the best test known then, but not a good one. And it had its drawbacks. Doubtless the reader remembers of the story of the railroad superintendent who was boasting to a friend of the efficiency of the organization he had built up. Pointing to a wheel tapper, he said, "That man has that job because of long faithfulness and experience." "Why does he tap the wheels?" asked the friend. The superintendent called the man over. "How long have you been with the road?" he asked. "Twenty years." "How long have you been tapping wheels?" "Eighteen years." "See," the superintendent said to his friend, "that's the kind of man we keep on an important job." Said the friend to the man: "Tell me why you tap the wheels." The workman looked puzzled. "Darned if I know," he said. To this man, whose type is nonexistent now in railroad operation, his job was his job, and there was no use trying to find out why he did it. , ... . He worked in the fog with which all uneducated and untrained people are surrounded, making no effort to get out of it..." Another version of the tale is told in the 1937 Will Hay British comedy film Oh, Mr Porter!. A German version of the story was told by the German humourist Sigismund von Radecki.

In Tolstoy's Anna Karenina, a railway worker is accidentally killed. He is probably a wheeltapper, and the man's gruesome death anticipates Anna's eventual suicide.