Drive Overheating

In our last competition, my team had several drive train overheating problems. It would over heat VERY fast if we were pushing against something.

I don’t know if you can help me fix the drive train I have now, or should we re-do it.

Here is the picture:
https://1105500718208150800-a-1802744773732722657-s-sites.googlegroups.com/site/323bbotebuilders/home/Copy%20of%20IMG_2624.JPG?attachauth=ANoY7co74aYt7R625ROIj5FpAWsAK0d18an368RjKb3DRR4dCdxNnfkyHO7GoivO-YZXKYwJEG81l-dUbOLF3LuH1S6lYgJs18mHon3pXFHH1J52BOd6Gp5fZvZXJlSW5McGtKSbseJ6NudB5gxoWEnfaTvFSVFuJ1jRT0HFeCqbKdmFfNKq9Hke_aGzkQCcOa8iVG9AV9kbauKKp3jG48wRyDXQ5Z5kbw%3D%3D&attredirects=0

Here is the drive we have now:
https://1105500718208150800-a-1802744773732722657-s-sites.googlegroups.com/site/323bbotebuilders/home/Stuff.jpg?attachauth=ANoY7cp785-PGDTM6g7EEhvBRftv50a8w0YXNQGAQYIscAyT5j_cOLMBLNQUCpuYoEk2b8at01qW1S_Q_Pr7mDv_o5bFWLvFCOGYzuajf8xnoAXGuls8pCc4RENts56o6MeikHGbYkKYuHic558bvoFVPMckCHe3-QbAwwUuJ9LaM5mLysonuVpxLBjTgicumV54uR5z5OQJM0EQRGNYlpb5GQyout8hVw%3D%3D&attredirects=0

We are directly powering 2 12 tooth sprockets with a 269 motor, and a393 motor set for High Power. We also have 2 omni’s with 18 tooth sprockets on them, chained to the powered sprockets.

Thanks!

What ratio is the drive at, I can’t quite see properly from the picture. Also, how heavy is your robot?

The only two ways I can think of to stop the drive motors overheating is to make the robot considerably lighter, or to gear the drive down more, for torque.

EDIT: Also, make sure that all of the shafts are free spinning, and there is not excessive friction. One way to do this is to remove the motors, and check that if you spin the wheels, they keep spinning for around 20 seconds or so. If there is excessive friction, they usually stop after around 5 seconds. If they are not spinning freely, make sure the metal for the chassis is attached solidly together so the holes line up. Also, lubricating the places where the bearings meet the shafts can help.

I added another picture for you to see better…

I am not exactly sure how heavy it is, I do not have the robot at my house, so I could not tell you right now.

I could guess it weighs around 15lbs?

Yes, like telemascope said, you need to give more information, including the number (and type) of motors on your drive train, the gear ratio, and the weight of your robot. All I can tell you now is that you should check for friction from all the moving parts on your drivetrain and consider gearing your chassis down, making your robot lighter, or adding more motors (pretty generic information).

Also, around how long does your chassis last in a match? You also shouldn’t be pushing other robots for extensive periods if you know your chassis has a tendency to overheat.

Hmmm, I would really check the weight of your robot, because your gearing isn’t very aggressive. So, to sum up, check for friction, check for dead/weak motors, make sure you have a consistently charged battery, backup battery before you decide to change the gearing or add motors (if you really have to) … because as I see it now, there should definitely be enough power.

We do not try to push, it is sometimes nessasary. I am watching a match that we were in, and we lasted for 30sec before we overheated. (I know, that’s bad)

Please refer to my previous post to answer one of your questions.

Here is the drive we have now:
https://1105500718208150800-a-1802744773732722657-s-sites.googlegroups.com/site/323bbotebuilders/home/Stuff.jpg?attachauth=ANoY7cp785-PGDTM6g7EEhvBRftv50a8w0YXNQGAQYIscAyT5j_cOLMBLNQUCpuYoEk2b8at01qW1S_Q_Pr7mDv_o5bFWLvFCOGYzuajf8xnoAXGuls8pCc4RENts56o6MeikHGbYkKYuHic558bvoFVPMckCHe3-QbAwwUuJ9LaM5mLysonuVpxLBjTgicumV54uR5z5OQJM0EQRGNYlpb5GQyout8hVw%3D%3D&attredirects=0

We are directly powering 2 12 tooth sprockets with a 269 motor, and a393 motor set for High Power. We also have 2 omni’s with 18 tooth sprockets on them, chained to the powered sprockets.

Ok, Thanks for that.

Our robot is fairly light when compared to most others, and it is on a 1.6:1 (speed) internal gearing with 4 393 motors.

I think your gearing, 1.5:1 with 2 269’s and 2 393’s with a 15 pound robot may be just a little too weak to push the robot, so it is causing a lot of strain on the motors, meaning they overheat. Unless there is anything you can remove from the robot to significantly reduce the weight, the actions I would take would be:

If possible, swap the two 269’s on the drive for the other 2 393’s, so you have 4 393’s on the drive, for a little extra power. See if that overheats.

If you cannot do that (if the other 393’s could not be replaced with 269’s) I would gear the drive down for more torque, and lubricate all of the shafts after checking that they are all spinning freely.

Alternatively you could just try and lubricate/check all the shafts now, and see if that fixes your problem, but considering you are only lasting 30 seconds, I doubt it will.

By the looks of the diagram, I’m pretty sure it’s the other way around, 12:18 (1:1.5, torque)

I will see if it is possible to swap the other 393’s of our lift and put it on our drive train.

One problem is that we are hopefully going to have our robot hold 6+ soon.

How do you think we should gear it down. Do you have an example of that?

I just made this video for you to see: http://www.youtube.com/watch?feature=player_profilepage&v=bCQdU6DDL6w

We are the robot with the 6-Bar linkage. The one with the back panel.

Oops, sorry, You are right. Wow, I have absolutely NO IDEA why it is overheating then, thats crazy. Are you sure all the motors are working fully? Also, check the shafts still. Wow, I just have no clue why that would overheat. Odd.

You should NEVER have to gear a drive further down than that, there has to be some kind of mechanical problem such as faulty motors or excessive friction for them to overheat that quickly. Are both sides overheating, or only one?

I do not have the robot with me, so I can not check that (wish I did).

Ok, just do it when you next see your robot. But as I edited into my last post, you shouldnt have to change the gearing. Look for faulty motors and excessive friction, because you should EASILY have enough power on that ratio with those motors.

I was wondering if we were going at a decent speed for this years competition.

In the video you can see us moving.

It It is mostly the left side. We (thought) we fixed that after our last competition. I guess not.
The right side also burns out, but not as fast.

I am going to check friction, and/or our bad motors.

The last thing I can think of that would be an issue would be your center of gravity. If your robot is too back-heavy, you might be pressing your back wheels into the ground while the front wheels don’t have much contact. I think Currahee solved this problem last year with a six-wheel drive, but that might be a little extreme if you aren’t 100% certain that that is the problem.

I was really thinking about the 6 wheel omni drive. I think that, and finding the excess friction/ motor problems is our next step.

We don’t have a competition till Feb, so we have a while…

I dont know, the field seems very confined this year with most of the interaction between robots occuring in 1 “quarter”, so it seems that driving around other robots that have a more powerful drive is very difficult. So I think a drive with a LOT of speed, say 2:1 on 4 inch wheels, is a little overkill this year. However, with your current gearing, Your robot should be very strong for pushing robots (if it didn’t overheat :p). It really depends on how you want to play the game. If you have a structurally solid robot, and are looking to push others out of the way a lot, your current speed is fine. Otherwise, I would look at speeding it up a bit (if you are able to sort out your overheating problem that is)

That is what I thought. First however, we need to figure out the overheating problems.

Heh, sorry to turn this thread into a strategy discussion, but we are going 2:1 on 4 inch wheels :P. It’s especially beneficial when the doublers and negators are introduced and the entire field is open – if it takes you a majority of the thirty seconds to score a doubler, you close a lot of possibilities with negation and last-second strategy.

If we are on the starting tile at 30 sec, then we can score the doubler in less than 5 sec. Unless someone is in our way.

Do you have a picture of your drive train, or a diagram.

We are using the biggest/longest C-Channel. Forget the measurements.