They both have about the same torque @ max efficiency (~2200 g-cm), roughly the same RPMs (60), almost the same gear ratio (~60) and the same volt output. The only thing that is very different is current output, 80 mA vs 246 mA, respectively. By Ohms law the second has more Watts but really what I want to know is how does the lower current affect performance if at all?
Will the torque output be the same but have less get-up-and-go at startup? Will it stall more easily and not maintain efficiency at high weight loads? Am I just being paranoid and can I really assume when they say "2100 g-cm" it will really output that the same way the other motor will?
KE7GKP: That's the current plan -- just try both and see what happens. I was really hoping for more understanding on the subject, though.
As far as applicability to be honest I do have a requirement but the question was meant to be theoretical, so maybe I'm making a 10 foot robot or maybe just a small 3D printer. Same principles should apply regardless of application.
Perhaps the question should be reworded to "when they tell you the torque, is there anything else that could affect the ability for the motor to turn at that force".
You need to look at the performance graph, not just go by the 'max efficiency' point (which depends on the power rating, windings, gears etc). All DC motor specs should include a graph of torque/current/speed at operating voltage. Note that gear trains can lose a lot of power/torque.
In my experience with commercial pumps, the datasheets are often exaggerated by 20% or more (or testing is skewed that much by using weasily methodology). In our shop we use thing like this a general guide or to compare similar pumps/motors to each other, but I've found you have to do your own testing for critical things.
I think a general rule is that DC motors will have max current draw and max torque at zero RPM. As the motor starts to rotate, those two values tend to decrease.
