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That is true, but for this specific differential in this specific configuration. As for the RPM on the Y axis: the torque does depend on the RPM in the sense that you'll get higher RPM and torque as you raise the voltage, but all of our tests are done at 9v. Under those conditions, varying the torque "controls" the RPM leading to the charts shown. If we had tested with say constant torque and varying voltage, we might graph it a different way.
That was very interesting. I was always wondering about how the coupling influences the lifespan of the motors, though. Obviously, that is pretty hard to really test without wearing out many motors over a long period of time, which would kind of defeat the purpose of testing that (saving on motors), I guess. 😄
Really interesting, this question has come up a lot before and I keep responding if the motors are the same type, just ignore the differential and hardmount them, mostly because any gains from the differential are going to be eaten up by transmission losses anyways and not use two different motors for a single function at all, but it's interesting to see a bit of data behind the reasoning. Have you tried this setup with PU motors, especially using the dual output (synchronous) configuration where the hub tries to keep both motors in-sync?
Thanks for doing all the testing required for this video. However one benefit of joining two motors with a differential would be finer control of speed and power. If you had both motors independently controlled, at least.
This may certainly be true depending on the goal and setup... I supposed we have an unstated assumption that we are building a "dumb" system like you would find in most train MOCs.
2:22 If its solid then obviously the m motor is trying to speed the xl up and vice versa but a gear ratio to make up for the difference in rpm would help I'm sure
@copernicon1 I'm just speculating since we haven't done any math or tests on this, but I think if the gear ratios are set up such that the motors run at approximately the "right" no-load speed, it's already pretty good. In this scenario, I don't think the motors should ever fight each other even if they are loaded unevenly, since they will both at least have a "positive" load.
