My team has to use 2 5.5w motors on our drivetrain alongside 4 11w motors, instead of 6 11w motors to accommodate the wattage cap. With this being said, we are having issues with the 5.5w motors overheating, and we assume that this is slowing down the 11w motors. Our current gearing ratio is 72:36, then the compound gearing connecting the 5.5w motors to the 11w motors is 36:36:12 (3 time overdrive), outputting 300 rpm. Any tips to be able to run the drivetrain for a full 2 minute match without overheating?
First, thank you for the detailed post. It is a great description, except for the fact that a we need a picture to fully help us understand your situation. Could we have a pic?
5.5w motors run at about 200 rpm (they have the equivalent of a green cartridge I believe).
A 36:36:12 means the 5.5w motor is spinning the 12 tooth at 600 rpm.
However, seeing as your drivetrain gearing multiplies your 11w motor speed by 2, there is no 300 rpm motor to multiply to 2 to get 600 rpm.
This means that the 5.5w motors are resisting the 11w motors and try to spin at a different speed, causing them to overheat.
This means that you need a different gear ratio. Which cartridge are you using for your 11w motors? This and a pic will allow us to figure out the right gear ratio for your drivetrain.
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From what I can tell from the post (and I agree that a picture would be best to say this), the 36:36:12 ratio is connected to the motor axles, not the wheels. This spins the motor axles at the same speed of 600rpm.
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Unfortunately I did not take a pic of one of our wheelbases, so I drew it to the best of my ability. I can get you an actual pic tomorrow morning. I’ll explain a bit, the 36t LS gear connected to 2 of the 72t gears is tied to a metal 12t gear that sits behind it on the same shaft, which actually connects the 5.5w motor to the rest of the motors/wheels/gears. We use blue high speed motor cartridges (600 rpm) on all of the 11w motors. Thank you for your help!
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How are you controlling the motors ? A motor group ? voltage control ?
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We use a motor group
and just normal spin commands ?
mg.spin(forward, 100, rpm);
or voltage control ? I only ask because using voltage control on a mixture of 5.5W and 11W motors may not be such a good idea.
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I apologize because I’m really not sure. I’m not our team’s programmer; all that I know about our drivetrain’s code is if we use motor groups. I can get you an answer tomorrow morning. Thanks!
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