pic: 254 Drivetrain



What has 6 wheels and goes really fast?

Soooo many people using that tread material for their whatever. Not being on a team, I have yet to see this stuff up close. Can you give me a rundown on why this stuff is good?

is that 8 double selenoids i’m counting? :ahh:

Question: What has 6 wheels and goes really fast??

Answer:What is another regional winner - and maybe more???

Nice looking bot this year guys. I was finally able to watch the Science Channel Documentary on FIRST featuring your team and I was impressed with your team’s showing in CA!!

Maybe this year is your year???

LOL, but that’s what we all want though, right?? To win the Championships??

See you down in Atlanta hopefully!!

BTW, what’s your weight in this picture??? It seems like it’s awful close to 130lbs… lol
I see lots o’ goodies!!

Whew, ok, lots of questions to answer:

Jessica - We’ve been using the waffle tread material since 2002, and it’s worked out great. The stuff’s pretty easy to find (it’s actually conveyor belt material you can order from McMaster), and it provides good traction on almost any surface.

pras - There are only 2 double solenoids. The other 6 are singles.

Elgin - Haha, thanks for the props. We weighed the complete robot last night, and it was exactly 129 pounds…it doesn’t leave too much weight for powdercoating, which we think will add about 2 pounds. Looks like we might have to resort to desperate measures like cutting off a couple cm off each bolt or cheese-holing everything :smiley:

If you’re using 8 solenoids, I’m guessing you’re gonna be going for multi-positioning with the pneumatics this year?

yea lets hear a little more about the beafy pnumatics this year you guys are using along with 60? Also i am curious about your drive train!

Our drive train is powered by 2 Atwoods and 2 drill motors, with 2 speeds, pneumatically shifted. The gearbox is a modification of 60’s design from 2001. The 6-wheeled base is modeled after Team 25’s awesomely fast and agile machine from 2003, with the center wheel on each side lower than the others by 1/8 inch, so that the robot rocks back and forth. This shrinks our wheelbase to about 13", allowing us to turn quickly.

The numerous solenoids on our bot are actually used for many different functions. One is for the cylinders that shift our gears, two are for our ball corralling “flaps”, one extends our bar-grabbing hook, one actuates our gripping hook for latching onto the mobile goals, one extend the “whips” that knock off the 10-pt balls, one double solenoid actuates the claw for manipulating the large balls, and the other double solenoid engages and disengages the winch for pulling ourselves onto the bar.

It must have been a fairly major modification as the drills were different then and we didn’t even have Chias.

Looks great. Everything looks super organized, even down to the different color pneumatic tubes. Good luck this year.

How do you fasten the tread material to the aluminum so it doen’t peel off?

I got to see 60’s robot REALLY up close (like I stuck my head in it) at Phoenix and it is amazing how everything is packed in there. They even have this little leadscrew mechanism on their PTO winch that winds the cable evenly so it doesn’t wind on top of itself. Anyway, on 60’s it appeared that the 4 corner wheel’s are toe’d in a bit. I was wondering what is the effect of/ reasoning for this and how does it affect the chain/sprocket alignment? Thanks.

Yea thats why they have the 6 wheel caster driver just like 25 last year. They have an offset for the center wheels a little lower then the front and back wheels. so the front and back are pretty much like a powered caster. It tips over on to either front or back generally depending on the direction its driving in. This allows them to have a great turning radius.

Yes, I know all about the 6 wheel drive and the center one being a little lower. It is just like a Home Depot shopping cart. What I was asking though is if the 4 outer wheels have toe in. On Kingman’s bot, it did appear to have about 2 degrees of toe in per wheel (or “toe out” depending on your perspective of front and rear of the vehicle)

The treads are held into the wheels with screws.

Just a guess, but I am willing to bet it wasnt intended to be like that (if it truely is more than just an optical illusion). My guess is that their tensioning devices have a tendancy to pull the sprocket side of the axle closer to the gearbox (in essence making it look like the wheel is pointing inward) I would guess it is partially due to the way they canteliver the wheels out, but also the way the chain is wrapped on the inside sprocket and how the wheel is moved on slotted mounts to tension it)

When I took a “close” look at 254’s robot, I did not notice it at all. I would be willing to bet it was not intentional if it was anything more than an optical illusion…

254/60 care to enlighten us?

I can’t speak for Kingman’s bot, but on ours, the wheels don’t normally toe out like that. Unless the chains are overtensioned - we noticed this on Saturday at SVR, and fixed it soon after.

Posted by phrozen solyd
The treads are held into the wheels with screws.

How do you cap the screws? Do you countersink them? We tried all kinds of things last year but we could never convince ourselves that we weren’t violating the “Traction devices may not have surface features such as metal” rule. Plastic fasteners were not as good as glue. Of course, that’s not what the four students that went around with their fingers stuck together for two weeks thought.

Thanks for the help,
Lucien

If you look at the wheels you can see that they are of two piece construction. Each side has a small lip on it so that when they are sandwiched together they grip the tread and keep it in place. The wheels are tapped and we use a pair of small pan head screws, not to hold the tread down but simply to keep the tread pulled tight. These are positioned so that they sit in the waffle well below the tread. If you are using screws to physically hold the tread down then you would need to use a larger head which may not sit deep enough to pass inspection.

There is no toe in unless something got bent, maybe I had better check! But seriously no toe in or out is not required to make the robot maneuverable.

The six wheel drive is the best system we have found so far it is simple, light, maintenance free, very little loss of horse power due to mechanical friction, and you will get the same traction as any other system.

Many people think you get better traction with a track system, not true. The only two things that effect traction are weight and the coefficient of friction of the treads. Surface area is not part of the formula. Ask your engineer.