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?
Hi, Could you use the Tank Tread kit from Vex??
Read this thread:
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.
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.
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…
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.
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.
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.
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.
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.
Team 48 has used Brecoflex belts with a lot of success over the years. Several pictures of past systems are available on CD. Some pointers:
Keep the belts properly tensioned, but not too tight
Protect the tread from sideload stresses as much as possible by using mutiple wheels/sliders along the area of the belt that contacts the ground, and keeping the “open” distance between the wheels/sliders to a minimum
Use a belt profile with a middle inner rib as opposed to flanged wheels–we typically used TK10-K13
If memory serves me right, we were using an 1880mm long belt with 4" wheels (2" boggie wheels) in our 36"-long tread module, and those belts were about $350…EACH…three years ago
Feel free to contact me if you have any other questions.
I have to add something for the teams using tank treads…
Turning on carpet with treads causes extreme electrical loads on your control system. A tight turn is guaranteed to put drive motors into stall. Stall currents on CIM motors is 129 amps each. A four motor drive will draw 516 amps and effectively lower the terminal voltage of the battery by almost 6 volts.
For some reason, I forgot about team 522, the Robowizards. They used tracks from 2003 to 2008 and they had a very effective system. (World Champs In 2006, IIRC)
Their 2007 iteration was quite clever and it solved the turning issue with the addition of a Ball Caster That was lowered to the ground with a piston and this allowed the drive train to lift itself up onto just the rear most portion of the tread allowing for efficient turning.
Here’s a link to their previous robots in the CD Image gallery. http://www.chiefdelphi.com/media/photos/tags/frc522
If you look back to the 2004 game, Team 234 used some unique treads that I haven’t seen much since. May be a little overkill for this game, but you can check them out here nonetheless - http://www.thistle.uk.com/
I know that that kind of tread is exactly what most of us had in mind, and personally, I don’t find them overkill at all. Especially when you want to be able to tackle the mounds head-on. We were looking for a custom, seamless tread plus components, and have heard rumors of a company who can do this for ~$800 total. Anybody have any leads? Thanks from team 2240.
I’d like to know if anyone has any suggestions on where to buy tank treads from McMasters or andy mark?
379 has had alot of success with tank treads. To my knowledge, we have never broken a tread, at worst, the material on the surface of the tread tends to take alot of abuse requiring a replacement to be on hand. Furthermore, we have always lowered our center idler wheel, which only allows about half of the tread to make contact with the floor and may cause a teeter totter action, but with a little better turning ability.