Tank Treads

[Andrew.Jensen]

Originally Posted by EricH

Wheels on one end, tank tracks on the other.

We were considering that, but in the end we decided to go with a whole tread. I forget the reasoning, however. But even so, it would still not change the question of where to get some treads for a reasonable price

[viperred396]

Originally Posted by EricH

Wheels on one end, tank tracks on the other.

As Andrew said we did consider it but then we decided not to because we think that the tracks will help us navigate the humps easier

As of now we were thinking about maybe adapting snowblower tracks to suit our needs

[Andrew.Jensen]

Originally Posted by viperred396

As Andrew said we did consider it but then we decided not to because we think that the tracks will help us navigate the humps easier

As of now we were thinking about maybe adapting snowblower tracks to suit our needs

Me and Bill were discussing finding synchronous conveyor belts, but they were rather expensive, like $400 a piece.

[EricH]

You could try http://www.andymark.biz/am-0566.html or http://www.andymark.biz/am-0565.html for some belting material. AndyMark also sells 1" wide x 10' long pieces, officially for use on a plaction wheel. Nothing says you can't put some 1" wide pieces of different types side-by-side to get a tread. You'd still have to figure out how to connect the ends, though.

[Andrew.Jensen]

Thank you, EricH, that might work well! It's cheap too! Just have to figure out how to rig it to work....

[skimoose]

Originally Posted by Andrew.Jensen

Me and Bill were discussing finding synchronous conveyor belts, but they were rather expensive, like $400 a piece.

As Madison said Brecoflex belts are expensive, and in heavy defense they can and will fail. Team 195 used Brecoflex belt tracks in 2005 or 2006

I'd check with someone from 195, but I recall hearing a failure rate of 10-12 belts over the competition season because of the heavy defense (pushing matches). That's a LOT of cash in replacement parts.

[viperred396]

Originally Posted by skimoose

As Madison said Brecoflex belts are expensive, and in heavy defense they can and will fail. Team 195 used Brecoflex belt tracks in 2005 or 2006

I'd check with someone from 195, but I recall hearing a failure rate of 10-12 belts over the competition season because of the heavy defense (pushing matches). That's a LOT of cash in replacement parts.

Thanks! thats good to know as we don't have a huge budget to spend and if they break that could really put us in the hole.

Just wondering do you guys think snowblower tracks might work if they were somehow cut down to size?

[Jerry]

Hi, Could you use the Tank Tread kit from Vex??


http://www.vexrobotics.com/276-2168.html

[Travis Hoffman]

Read this thread:

http://www.chiefdelphi.com/forums/sh...ad.php?t=59943

There is a Canadian company that supplied conveyor belting to both 1114 and 2056 whose name escapes me right now. I'll have to dig through my 2008 orders to find out the name. They had, in my opinion, a "better" way of joining the ends of their tank tread conveyor belts together to provide a stronger seam. They sell products that are compatible with Brecoflex pulleys.

Last I checked, Brecoflex provides discounts to FIRST teams for their products, but even so, the materials are expensive, especially when you factor in spare parts costs - you WILL want to purchase spare belts.

Brecoflex CAN work without becoming a total horror story - we've had success, as has 379, and others. But all tank tread systems are relatively heavy and expensive, and require numerous spares on hand to give a team a decent sense of security.

All I've got to say about full-length tank treads is - think what happens when a 25"+ long tread starts climbing a 45 degree bump. Consider what a bot waiting on the other side might do in such a leverage-advantageous situation when contact outside of the bumper zone on a bump is permitted per the rules.

For a self-inflicted simulation of the potential situation I'm describing, check out http://www.youtube.com/watch?v=CjHMb55EXmY. Proceed accordingly.

[Tom Line]

One of the biggest problems you'll find with treads is difficulty turning. In fact, 1718 had custom treads their first year that turned out to be a disaster. The treads were so sticky that they worked great when the robot was 40 pounds. When the team finished the robot the right before ship, they discovered that at full weight the robot would not turn. In fact if you tried to turn the treads would stay stuck linearly to the floor and the robot would drive right out of them.

Treads are NOT a trivial design excercise, and I would caution anyone against trying them without realizing you may have to make a very sizeable time and engineering investment (not to mention weight and cash) to make them work correctly.

[nnfuller]

Originally Posted by Travis Hoffman

All I've got to say about full-length tank treads is - think what happens when a 25"+ long tread starts climbing a 45 degree bump. Consider what a bot waiting on the other side might do in such a leverage-advantageous situation when contact outside of the bumper zone on a bump is permitted per the rules.

I think this is something all teams need to keep in mind. Basically the GDC has declared "the bumps" as a kind of free for all zone. i can definately see teams trying to take advantage of this leverage situation...

Originally Posted by thefro526

Check out this link:

http://www.chiefdelphi.com/forums/sh...ad.php?t=60591

It's an old design by Craig Hickman, I'd suggest PM-ing him with any questions, I'm sure he'd be more than glad to help. (His user name is CraigHickman)

I'd be glad to answer anything about this design. I'd offer to send out the CAD, but I don't exactly own the rights to the design of some components. A team I'm currently involved with is considering this system (nearly an analogous design to that one, actually) with some minor changes, and I'm fairly certain a gearbox redesign as well. The Outback system is fantastic, and this is one of the first games since 2004/5 to really want tracks for climbing things.

Originally Posted by rkelly23

You would need to do some rather extensive thinking about the suspension. Our team is kicking this idea around and my hint is to go look at the mechanical structures of military tanks. Any other comments about tank treads and teams that are planning to use them are highly appreciated.

A properly designed track system for robotics use should have a few factors:
-Self tensioning
-Robust
-No need for suspension
-Lightweight
-Very rigid to avoid torsion when turning in place
-High CoF for pushing traction (>1.5 is preferable. Red Linatex is 1.6, IRC)

If you can do all of these, your track system will succeed. Any failures in the above list can lead to some fairly catastrophic breakdowns, and a large cost in belts.

[Cory]

Originally Posted by EricH

You could try http://www.andymark.biz/am-0566.html or http://www.andymark.biz/am-0565.html for some belting material. AndyMark also sells 1" wide x 10' long pieces, officially for use on a plaction wheel. Nothing says you can't put some 1" wide pieces of different types side-by-side to get a tread. You'd still have to figure out how to connect the ends, though.

Roughtop or wedgetop would be totally useless as the backing is smooth. You want a tread with backing. Transmitting power through a slick surface is not a very good idea.

[Akash Rastogi]

I would recommend Brecoflex for the final design but for prototyping, inverted and double sided timing belt is an appropriate substitute as the pulleys (wheel?) for Brecoflex would take time to order and ship.

[Ross340]

one thing you may want to look into are blower belts. aka supercharger belts. they come 2-3'' wide and you're not gonna skip or strip the teeth off of or break or stretch one of those puppies. ever. they can be pricey but come in a wide range of sizes.