Quote:
Originally Posted by Brian Selle
This ^ with a 0.8-0.9 for gearbox efficiency will get you close. For this example, 65% command: 10,000 rpm * 0.65 * 0.8 = 5200 rpm free speed. 5200/2500 yields approx 2:1 gear ratio.
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Consider the following thought experiment:
Take a CIM whose free speed is 5310 rpm at 12 volts and connect it to a good quality properly assembled and lubed 2:1 gearbox whose output shaft is connected to nothing (no load).
Using the same computation you did above, the CIM's speed would now be 5310*0.8 = 4248 rpm.
Now go to the motor curves for CIM and you'll see that CIM is drawing 29 amps.
Do you believe that? If not, where is the error?