pic: FRC 1293 Drive System CAD

CAD of our drive system for this year, with a couple things hidden for the visibility of the internals. The thick white material is UHMW, at 1.125" thick on the outer two segments and 0.75" on the inner segment. This gives room for the belt, which is slightly under 3" in width. The black is a sheet of aluminum, and a plate is likewise placed on the side closest to the viewer in this picture. The chain run is done inside this system to prevent anything from getting caught in it, and the shape of the cutout for the chain run is done to create even more chain wrap than 180 degrees.
The gearbox on the opposite side uses two CIMs and a FP in a gearbox made from Toughbox internals and a custom mounting plate. The mounting plate on the side of the drive system is actually integrated into the drive train.
And, solving the main issue with our past tread designs, the bottom is in a V-shape mimicking that of 6 wheel drive designs with a dropped center.
Bumpers are mounted using support brackets that come up from the top of the tread and are backed with a 1/8" sheet of aluminum (as per rules on support along the entire length of the bumper).

Any questions/comments?

Looks awesome, Where do you get your treds from?


We get the belt donated from a local sponsor (I’m not sure who), but the belt is manufactured by http://www.unichains.com/

The weight is about 20lb/side. A drivable chassis with bumper mounts, electronics, and everything required basically to move is 70lb. We’re not done cheesing the interior yet, though, and hope to drop another 5-10lb before jetting it.

70 pounds sounds really good for this year. If your hanging mechanism and kicker weigh more than 50 pounds, your chassis isn’t what needs weight reduction. :slight_smile: (shamelessly stolen from mr. forbes)

Where have I read that before? :slight_smile:

Big drop when it crests the bump…hope it survives if you plan on driving over.

For those interested about the belting. It is a product of unichain, and it is the “Uni-QNB with Rubber” belting. Heres a picture of it in the flesh from their catalog.

Also, heres a picture of it from our 2007 bot.

This is some amazing stuff. It’s original purpose is as conveyor belting, but as a tread system it is terrific. The links are 1" long each and are easily removed. They have incredible traction, and are very flexible along their joints. Also, they interact with a sprocket on the other side that is very easy to water jet out (given you use the specs provided in the catalog).

We’re still working on the cheese and bumper mountings, but we’re hoping to get her once again back on the Jenny Craig, this time pre-cut. (Our 2007 bot had quite the post-waterjet cheesing going on once we realized we’re 5lb over)

I’m sorry if I don’t understand, but what advantage does the robot gain from this tread system over the out-of-the-box raised one included in the KOP? Besides that, looks awesome and I’m amazed at the CAD and machining skill.

Well, there are a few advantages and a few disadvantages as with any system.
The two main advantages are the center of gravity and the climbing ability. The center of gravity for our drive train is only around 3" off the ground, which would be difficult to achieve with the kit bot and makes it more likely to tip over. The tread system also helps to maintain traction when going over the bump, since the entire bot can follow the slope, increasing the contact area and decreasing any bouncing motion.

Past those, it integrates the chain run directly inside in a way that it’s almost impossible for the chain to come off, even without a tensioner, while protecting it. It also lets us achieve some nifty styling options that couldn’t be done with a kitbot, but that’s getting into opinion.

The disadvantages are the usual with going custom - the need for fabrication, longer time to get a driving bot, potential for mishaps in the actual design, etc. but we feel that our experience with tread systems in past years and the availability of sponsors to do fabrication makes it worth our time.