Wheeltapper

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

Typically employed at large 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 overly 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.

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 German version of the story was told by the German humourist Sigismund von Radecki.

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Wikipedia