DOES STEEL GET TIRED?

Pukekohe & Waiuku Times, Volume 6, Issue 239, 5 January 1917, Page 4 (Supplement)

DOES STEEL GET TIRED?

ACCIDENTS CAUSED THROUGH OVERWORK.

On tlio fuc? of it, tliis question seems x ridiculous one, but it is a well-known fact tuat cutting tools such as razors, chisels and the like, if used continuously, until they have apparently lost their keenness, will, if they aro laid aside for a time, cut as well as ever, ana some workmen, on a long job, will uoO two tool*—one in use an 1 ono resting. To ;i great extent it is the same with machinery, and machines .which have run for years satisfactorily, when subjected to a long run of overtime, will unaccountably break down.

For instance, a prhiting-raaehine, which had been running well for some years at normal hours, was suddenly required to work overtime. It stood • the strain for some woks and then mysteriously broke down —one of the main steel shafte, as thick through is a man's arm, snapped clean in two. As there was no sign of a flaw in the shaft it was submitted to an expert, and his opinion was that the steel had simply got" tired and broke; that if the machine had been allowed a complete rest the accident would not have happened. Examples of this peculiarity of metals might, no doubt, be multiplied, hut one more will suffice. A large steam engine, developing two hundred horse power, had a fly wheel weighing twenty tens. This fly wheel was well supported, and when, through a breakdown of a secondary engine, the first engino had to run the night-shift as wrll as the day, the machine stood the strain for some time, hut one day, without warning, the huge flv wheel burst. "

Experts were called in and again their verdict was that the metal had got tired, and parted under the strain.