What can we do to prevent our motors from over heating? After every match we have to either switch the motors out or let them cool down.
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Do the middle wheels spin faster than the others?
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Yup. You got it. The wheels are trying to spin at different speeds.
The driven gear on the axle of each wheel needs to be the same size. Also, a 7:3 ratio for 200rpm carts would be 467 rpm, which is WAY too fast for 4 motor drive. If you put a 60 tooth gear on the middle wheels you would be at 280 rpm – with 3.25" wheels that is 48in/sec, which is not fast, but within the capability of 4 motors.
A better option without a frame rebuild would be 60 tooth on the motor shaft and 36 tooth on the wheels. 5:3 ratio, 333 rpm, 57in/sec. Upper range for 4 motor, but fairly easy to add 11 or 22 watts to.
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Yeah middle gear is smaller so the difference in wheel speed causes extra force on the motor to power it.
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Yes, the middle wheel goes faster.
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That’s makes a lot of sense. We’ll try switching to 60 tooth on the motor shaft and 36 tooth on the wheels and see if that is better on the motors.
Thank you!
David
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Could we also just remove the middle wheel and keep the gears?
Our first attempt we took the center wheel out. It has affected the way it moves during the autonomous period. If we switch out the gears it looks like we will also have to move the motors as well.
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What you can do is to make the wheel free spinning but keep it on the axle with the gear so you stop ok have a traction wheel just not powered by the motors
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The unworkable gearing would have affected the autonomous. Converting to a workable gearing would have all the same steps in autonomous, but you would need to change distances and angles.
Yes, you would need to move the motors – likely 4 screws per motor, so 16 screws. Even at about 2 minutes per screw, that’s a half hour job. Don’t get stuck thinking changes are too much work.
It is a fact that you made a mistake, and time will be needed to correct it. No big deal, just get at fixing the problem.
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This is a quick fix, but the auton will still need to be modified and the final speed is too high for 4 motors.
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That’s what we did, now we have to test it to see how it does.
It’s working great. Had to make a few minor adjustments on the autonomous. Thank you everyone for your input!
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