Finding R.P.M.
QUT of curiosity, the technically minded motorist sometimes wishes to ascertain the engine revolutions of his car for any given road speed and at odd times requests are received for the proper formula. The revolutions per minute for any given speed can be worked out by this formula: Revolutions per minute equals M x G x 336 divided by D. M. is miles per hour, G is the gear ratio, 336 a constant, and D the tyre diameter in inches. To be exact, it •<! hn=t to m»asure the tyres at normal pressure with a tape measure, rather than go by the markings on the side walls. As an example: A car is travelling at. 40 miles nor hour; its gear ratio is 4 5 to 1 and the tyre diameter 30 inches; using the above formula we find that the engine speed is 2,01 b revolutions per minute.
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https://paperspast.natlib.govt.nz/newspapers/PBH19381231.2.111.2
Bibliographic details
Poverty Bay Herald, Volume LXV, Issue 19826, 31 December 1938, Page 11
Word Count
150Finding R.P.M. Poverty Bay Herald, Volume LXV, Issue 19826, 31 December 1938, Page 11
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