We are trying to run high torque motors for our drive motors and they are overheating or something thats causing them to shut down and come back on after the sit for a couple seconds.
What gear ratio are you using, and how heavy is your robot?
we have the 393 motors with a 36 to 12 tooth gear ratio on the wheels for speed. the robot is actually rather light still because its just a chassis with side shuffle wheel and drive wheels set up
How many motors are you using on the drive? Check for excess friction.
You are running a 1:3 (speed) ratio on the drive. That is pretty fast. Most people only use a 1:1.6 or 1:2 (speed).
There’s some good background information on why this happens here. As stated before, check to make sure your motors aren’t doing too much work because of excess friction or gearing.
If you have further questions please ask.
1:3 is your problem.
Go 1:2, or 1:2.4 at most. We tried 1:3 earlier this year, and had exactly the problem you described. Slow down.
Not necessarily. We were using an 8 motor 1:3 earlier on in the year and it was doing fine. We just scratched it cause it was to fast, and we didn’t want to waste 8/10 motors on the drive.
Back on topic. I think you should slow down to a 1:2 (if you still want to go fast). An internally geared 1:1.6 drive is close to 1:2, so both will give you good speed and shouldn’t die (as fast).
You also don’t want things too tight or squeezed together on a drive. That creates a ton of friction which will kill your drive faster.
Yeah, with 8 motors you can do 3:1. But we’re talking about average robots, with are 4-6 motors. You may be able to do it with 6, sure, but if he’s overheating then the gear ratio IS the problem.
He needs to slow it down.
Another vote for the high ratio being the problem with that number of motors.
If you have chain, I recommend trading it out for a direct drive system. This helped our burning out. It increases the efficiency at which it runs.
We had problems with our motors overheating last year during sack attack. Our bot was very light weight and had problems pushing the sacks around. Also the sacks would get caught in our gear train if we tried to drive over them. When this happened, one side of our robot would simply shutdown. After doing some research on it, we found that the 393 motors have a thermal switch on them. If the motor exceeds a certain temperature (which I can’t remember) the switch is thrown and the motor will not run until the motor cools down.
This actually happened to us during on of the qualifying matches at worlds last year and almost got us disqualified because another robot got pinned right when the thermal switch turned the motors off. We were able to move with a second to spare.
I pulled off a 3:1 ratio on 4" high traction wheels
with just a drivetrain with four 393 motors. Never had issues overheating. Because of this, i believe your issue is bearing friction or aggressive driving.
During relay for life, we had about a 6 pound drivetrain chained at 18 to 6. We drove the robot around the track almost continuously, stopping only to swap out batteries. However we did not shift directions like a competition robot. The motors did get hot however. During this time, we also used 1x25 bars as heat sinks. We really don’t know if they work however. After all, there are too many variables to consider and get an accurate result. You can try decreasing jerk
I believe multiple teams used a 3:1 speed drive with 2.75 inch wheels in gateway however. I believe that was fairly successful
No competition robot is 6 lbs. I’ve gone as light as I can this year, and I’m still hovering around nine. I would be impressed if anyone got under 8.
3:1 with four motors is typically a bad idea, it’s causing his problem, and he needs to slow down.
Another vote for too high of gear ratio.
As mentioned earlier, check for friction outside of the motor. This can be from too many spacers, too tight of chain, or anything really. Besides the friction external of the motor, check internally the motor as well. If you open up the front side of it (side with shaft), than put some lube on them it will run real smooth. If you do both of those things than you will have a smooth running robot.