Physics Help Forum Spur Gearing problem

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 Apr 8th 2012, 01:26 PM #1 Junior Member   Join Date: Aug 2011 Posts: 7 Spur Gearing problem Hi got a question and have no idea where to start it A power tool will need a reduction gearbox giving two possible speeds. The input is from a 500W electric motor with a 3000 rpm speed. The two output speeds are about 950 rpm for the slow speed or at about 1900 rpm for the fast speed. I wish to use spur gearing. I have done a quick calculation on a spacing of about 25mm and this suggests that a spacing of exactly 27 mm will give me answers that give this result within the tolerances that I am happy with, using a module of 1. How many teeth are there on each gear and what are the precise output speeds? Givens Input Power = 500W @3000 rpm Required Out speeds = ~ 950 rpm & ~ 1900 rpm Spur Gearing 27mm spacing (? not sure what the spacing means) Module = of 1 Unknowns No. of teeth and exact speeds (rpm) of each gear. Answer 13 – 41 low 951 rpm 21 – 33 high 1909 rpm I know that I may have to change the rpm to rad/s and am able to do that. I also know how to calculate the torque produced from the input, but am pretty much lost after that. I would also love to know what calculations may have been used where it says "quick calculation", but that just due to curiosity. Thank you for any help in advance.

 Tags gearing, problem, spur

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