pic: Team 610 Off-Season Tank Drive Prototype

[s_forbes]

Neat. I think our team was going to try to prototype a tank tread style drive train after seeing their success in last years game, but I don't know how far they got.

I like the use of sheet metal, it looks like a nice cheap way to build a strong frame. It looks like you may want some diagonal braces in there though, it doesn't appear to have too much to prevent it from getting knocked out of square. I might be missing something, though. I look forward to seeing how it turns out, looks like fun!

[Jonathan Norris]

How are you going to drive the belts off of the drive wheels?
Why not move the transmissions to the back in order to give more pushing power if pushing from that side?
How are your going to run a chain from the transmission when the sprocket seems to be mounted below the drive wheel?, the tranny housing will be in the way.

Wow thanks for all the questions. So to drive the belts there is going to be #35 chain from the gearbox's to the rear sprockets (you can see one in the back left corner). The reason the gearbox's are place in the center and not in the rear is because of the HUGE importance of keeping the center-of-gravity over the center idlers in a tank drive system. In my discussions with 1114 they couldn't stress this point enough to me, how important it is to have the CoG centered. The sprocket is mounted directly on the rear axle, the drive wheel (pulley in this case) is 4" diameter and there is plenty of clearance for the transmitions.

Why is the frame so "skimpy" for a tank like that?, if you want a powerful drive train build a frame to take a lot of beatings

the reason this design is so "skimpy" is because of our experiences last year and having to drill thousands of holes in out robot you can say we are a little weight conscience . Also, this is a prototype, it is designed to be simple and prove the concept. In an age with bumpers there is no need to have 1/2" aluminum walls for your robot to survive a season, but yes for a FIRST robot we would beef it up a bit. As well we were only able to find 1/4" thick 3" square aluminum, where this CAD is 1/8" thick. So the real thing will be beefier that this CAD makes it look.

We are actually planning on testing two different spring tensioner system. The first one is on there, if you look closely at the top of the tracks you can see an area cut out where we have a tensioner pushing up on the bottom of the track. Also, we are planning on testing the traditional spring tensioner pushing on one of the wheels to tension it.

I like the use of sheet metal, it looks like a nice cheap way to build a strong frame. It looks like you may want some diagonal braces in there though, it doesn't appear to have too much to prevent it from getting knocked out of square. I might be missing something, though. I look forward to seeing how it turns out, looks like fun!

We just bought a new break/shear system which we will be using for the first time on this robot. We have heard a lot of great things about working with sheet metal, it will be interesting to see how this build goes for us.

thanks for all the questions, keep them coming,
Jonathan Norris

[Andy Y.]

Andy Y. here,
Designer/CADer of the tank drive

Thank you for your questions. It could help us later after we build it in troubleshooting problems. I see Jonathan Norris has already answered the questions above. I'll check for further questions if any of you have some.

Note: Special thanks to Jonathan Norris, Derek (our amazing lab technician), Mr. Morrison, and Mr. Grant for helping me with the tank drive design. Without them it would no doubt have been a half baked job.

Andy

[Madison]

I don't know if it's worth the hassle of dealing with ordering from the US, but onlinemetals.com has 3"x3"x.125" tube.

http://onlinemetals.com/merchant.cfm...owunits=inches

1/4" wall is an enormous weight penalty and very likely much too beefy for nearly anything you'll throw at it.

[Andy Y.]

Originally Posted by M. Krass

I don't know if it's worth the hassle of dealing with ordering from the US, but onlinemetals.com has 3"x3"x.125" tube.

http://onlinemetals.com/merchant.cfm...owunits=inches

1/4" wall is an enormous weight penalty and very likely much too beefy for nearly anything you'll throw at it.

Thank you for the site reference. We chose to use 1/4 in thick 3 in square for several reasons. Firstly, yes it is stronger. Secondly, we wanted the extra weight for our prototype since we won't have the weight of a robot on top of it. And finally, I forgot to add the wall thickness on my parts list XD so we got 1/4 instead.

Andy