Math CentralQuandaries & Queries


Question from Sheila:

I am trying to figure out the speed (ft/min) of a conveyor.
It has a 1HP, 1200 RPM motor with a reducer that has a ratio of 60:1.
My reducer sprocket pitch diameter is 7.027 and my drive sprocket pitch diameter is 11.474.
How do I use this information to find the speed at which the conveyor moves?

Hi Sheila.

I'm no expert on motors and without a diagram I'm kind of at a loss to identify exactly what components interact how. However, there is a web page I found here: which includes a formula relating most of the information you've provided with the belt speed. Perhaps it will be useful for you.

In general, gears and belt drives change rotational frequency by the ratio of their circumferences, which is the same as the ratio of their radii. So I expect a ratio of 11.474 / 7.027 (or its inverse) will need to be included.

Hope this points you in a fruitful direction.
Stephen La Rocque.

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