Tank Tread Help

[Jstack14]

We are in need of some help...

We are making a robot that is about 3.5 ft. by 2 ft. wide. We are going to put some sort of tank tread on it but what we currently are using is not working. Currently our tread is two lines of chain that go around two sprockets each. They are connected with strips of Lexan that are riveted into the chain every fourth link. On the sprockets every fourth link is cut off so that the rivet pieces of Lexan line up with the cut out teeth on the sprocket. This system would work, but all of the holes on the Lexan pieces don’t line up, so the chain slips off often and then it simply doesn’t work. We are wondering if anyone has suggestions how to fix this, because if we can’t fix it we will have to come up with a new idea. We are thinking timing belts and pulleys, but we can’t find any that are wide enough. Does anyone have any suggestions on how wide the belt would have to be to be effective, and where we could find a fairly affordable belt that size?

Or are we approaching this entirely wrong?

[viperred396]

we used timing belts for our robot this year. We bought them at http://www.brecoflex.com/ With them you can get custom treads at any size

[Tom Ore]

I couldn't quite follow the description of what you are doing. Is it possible to post a pic?

[MrForbes]

Also could you tell us what "affordable" is? Under $100? Under $1000? Under $10,000?

[commodoredl]

This year our Breakaway robot used a tank tread drive system. In order to save money, we designed it to use triple-wide drive chain run on two sprockets, rather than buying belts from Brecoflex. I think the chain was available through some surplus store; I don't know where we bought it. This worked out well for us since the chain was wide enough that we could use it as a track and it never slipped in competition. To make it legal, we attached small pieces of hose using bolts, as you can see in this picture.

[Jeffy]

Check out the local tractor supply store, you might find something that will suite your needs. In Oklahoma there was a team (i think it was 2824) that used some treads from a tractor supply equivalent and they never threw a belt and had crazy pushing ability. The treads I am thinking of were about 6 inches wide.

[Jstack14]

I am waiting for the pictures to be approved or whatever so I can give you the link on Chief Delphi. Also for the price question under a thousand is a must, and honestly under 500 would be ideal. The cheaper the better because we already have invested a decent amount of money into the system we have which is not really working, and we don’t have a large budget to work with.

[Nevets Amstier]

Originally Posted by viperred396

we used timing belts for our robot this year. We bought them at http://www.brecoflex.com/ With them you can get custom treads at any size

I recommend buying a pulley/belt system from a company called "Polytech", our team was EXTREMELY unsatisfied with our Brecoflex belts. Not only were they delivered way behind schedule, but also they snapped after only 3 or 4 matches, whereas the comparable polytech belts lasted an entire regional (12-14 matches) and an entire day of practice on our own field.

http://www.polytechdesign.com/

anyway,

I liked 578's style of afordable belts, they worked well at FLR where we competed against/with them.

[Ty Tremblay]

on this year's winning NASA Lunar excavation robot, there were these tracks.

Thy consisted of aluminum C-stock fastened to chain that had special links that allowed things to be attached to them without modifying the sprockets. you can find them here: http://www.mcmaster.com/#roller-chain/=6s0umt Scroll down to the bottom and click on accessories. Unfortunately, they're only available for 35 pitch chain.

EDIT: Here's a pic of the link.

[PAR_WIG1350]

I've never done this before, but I would suggest timing belt since it requires fewer modifications than chain, and has fewer moving parts and joints. also, I would check to make sure the chain/belt is tensioned properly and hasn't stretched.

[JohnFogarty]

Handmade..cheap...and the best treads i've seen. http://www.maikenmagic.com/?ref=show...20Build&num=23

[JohnFogarty]

here's an innerworking picture http://www.maikenmagic.com/?ref=show...20Build&num=11

[sanddrag]

May I first ask why you think you need tank tracks/treads?

[JesseK]

The simple and cheap solution may be to go with a higher pitch chain. I would think #35 at the smallest, but even higher may be necessary so the teeth of the sprockets have more chain to dig into as the whole assembly rotates.

I'd also recommend you fix the "holes don't line up" issue. It sounds like you have many lexan pieces and they all need to be identical. A jig, automated process, or assembly line may be in order. Look for defects as they come out of cutting/drilling and discard any grossly imperfect pieces.

[Jstack14]

Originally Posted by sanddrag

May I first ask why you think you need tank tracks/treads?

Well honestly i do not think we need tank treads, however our team is set on tank treads.