I am trying to use the design calculator and there is a field in there for gearbox efficiency. How do I know what that is for a chain driven gearbox of our own design?
Help
Bruce
93%
(just a guess, but that’s probably what you’ll have to live with, is a guess)
Chain and spur gears are usually somewhere around 95-98% efficient if assembled properly.
To determine overall efficiency, you have to multiply the efficiency of each stage. A KoP drive train, for example, has two stages of gear reduction and a third stage of chain reduction.
If we assume that each is 95% efficient, you’d multiply .95*.95*.95 and end up with about .86. So, that drivetrain has an efficiency of about 85%.
For comparison, if you assume 98% efficiency in each stage, overall efficiency jumps to 94%.
That’s a good explation of how to estimate the efficiency of the gearbox/drivetrain. And the accuracy of your estimate may or may not be very important, depending on what it is you’re trying to figure out using the calculator. You could plug in some different numbers such as 85%, 90%, and 95% and see what difference it makes.