pic: 254 Drivetrain

[Travis Covington]

Originally Posted by sanddrag

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)

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?

[phrozen solyd]

Originally Posted by Travis Covington

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.

[Natchez]

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

[Dennis Jenks]

Originally Posted by Natchez

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.

[Glenn]

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.

[Cory]

Correct me if I'm wrong, but doesnt surface area matter in instances when the tread material deforms a surface such as carpet, and "interlocks" (for lack of a better word) with the individual fibers?

Cory

[ChrisH]

Originally Posted by Cory

Correct me if I'm wrong, but doesnt surface area matter in instances when the tread material deforms a surface such as carpet, and "interlocks" (for lack of a better word) with the individual fibers?

Cory

Glen is right as far as he goes. But sometimes the co-efficient of friction varies with either the load or the load divided by the area. This usually happens in systems where something is deforming enough to be noticable. Generally these interactions are also non-linear and need to be quantified emperically. At least that is easiest for our type of systems.

There were a couple of very good white papers posted by IBApril180 about this a while back that address this question. Here are the links.

http://www.chiefdelphi.com/forums/pa...le&paperid=120
http://www.chiefdelphi.com/forums/pa...le&paperid=119

[sanddrag]

Originally Posted by Glenn

There is no toe in unless something got bent, maybe I had better check!

There definitely was some toe at Phoenix. I'm willing to bet it is what Travis said above.

[Collin Fultz]

would it be possible for 254 or 60 to post a white paper about their drivetrain? of course...i guess I can always see it in NEWTON! or just e-mail me information

collinfultz@att.net

[SteveK254]

Originally Posted by collin234

would it be possible for 254 or 60 to post a white paper about their drivetrain? of course...i guess I can always see it in NEWTON! or just e-mail me information

collinfultz@att.net

Hi Collin,

We don't plan to generate a white paper on the transmission, due to focusing on our collaboration white paper. However you are welcome to any of our drawings as well as an invitation to unlimited questions. Please stop by our pits (60/254) at the Nationals and we would be happy to answer any of your questions. You can also see the working model.

[Stephen Kowski]

I'm wondering how 60/254 packed their solenoids together sooo tight.....is there room for the hose/fittings....can anyone elaborate...?

[Travis Covington]

Originally Posted by Stephen Kowski

I'm wondering how 60/254 packed their solenoids together sooo tight.....is there room for the hose/fittings....can anyone elaborate...?

It is a SMC solenoid manifold. It is available through any SMC distributor (Motion industries etc). It has a common pressure input, and has ports for the solenoids on top and quick disconnect fittngs on the side, 2 for each solenoid. Block off plates are available if you decide to remove a solenoid or cannot purchase a small enough manifold. (in our case we needed ports for 7 solenoids, and thus had to purchase an 8 port manifold, we blocked off the 8th port) I think they come in manifolds of 2 and larger (maybe 4, I can't remember) and I recall them being in multiples of 2.

Hope that helps!

[Collin Fultz]

Originally Posted by SteveK254

Hi Collin,

We don't plan to generate a white paper on the transmission, due to focusing on our collaboration white paper. However you are welcome to any of our drawings as well as an invitation to unlimited questions. Please stop by our pits (60/254) at the Nationals and we would be happy to answer any of your questions. You can also see the working model.

i'm terribly sorry that I didn't get to see the model...i was either talking to judges, trying to shoot balls, or ogiling over the HOF displays...plus i didn't see your post until today. if there is any other way to get the information, digital pictures, gearing ratios, or anything else that would be great...thank you!

[magnetnerd]

How did you make your tires, or did you order them? Specifically, the wheels and not the waffle treds.

[Cory]

They made them. I believe it was explained elsewhere, but they are 3 separate pieces. The hub, and then the two side plates that sandwich the hub. By design, the two pieces trap the tread in the wheel well, so that screws aren't needed to fasten it.