designing a three motor gearbox

[cgmv123]

Originally Posted by pmangels17

My apologies. I forgot for a moment that the MiniCIM and CIM were different RPMS. However, going from all MiniCIM to all CIM wouldn't be a problem. You should definitely use a slight reduction on the MiniCIM, though I am not positive on the exact ratio required.

1.1676082862523540489642184557439:1 or 620:531 or 62:53* or 6:5*

*Approximate

[1683cadder]

How close do the gear ratios need to be?

[T^2]

They don't. Slower motors will act as loads on faster motors. If you're incorporating CIMs and MiniCIMs in the same gearbox, you can use 12-tooth pinions on the CIMs and 11-tooth pinions on the MiniCIMs (or 14t and 12t respectively), which will get you close enough. In all honesty, you can probably use the same pinions on the motors, and they'll balance each other out without too much stress.

[EricH]

Originally Posted by 1683cadder

How close do the gear ratios need to be?

This question doesn't make sense in the context of the current discussion. I believe the question you're asking is, "How close do the RPMs need to be?" unless you're looking into what the different stages of the gearbox will be.

The answer is, they WILL be the same, eventually, due to the single gear they both go to--it can't travel at two different speeds at the same time. However, having the speeds wildly different is going to really annoy one motor or the other or both. Given that you're talking about 5K RPM and 6K RPM motors, I'd shoot for within 100-200 RPM difference; that should be close enough to work with and within the rated speed tolerance.


Just in case you were asking about the different gear ratios in the gearbox, though, the answer is "it depends". Depends on design, depends on designed speed(s). Each reduction stage, as a rule of thumb, should be less than a 10:1 reduction by itself (total reduction of the gearbox can be a LOT more).