Re: Where can we find good pneumatic wheels?
 

Didn't 70/494 have a crab drive in the wide direction?

Re: Where can we find good pneumatic wheels?
 

1276 used pneumatic wheels and hubs intended for mountainboards in 2005 for our two powered rear wheels. The front two were omniwheel casters. We played in the vicinity of 10 matches (qualifying plus 3 elimination rounds), had a week of driver practice and two more years of abuse driving it on just about everything as a defender for driver practice and demo bot. They stood up just fine. I don't remember the vendor, it was just some mountainboard shop we found online.

You can barely see the top of one in the lower right.

One of the reasons we gave up on pneumatic wheels was they make driving straight (especially in autonomous) a really big pain in the butt. We found how straight we drove could be impacted hugely by a relatively small difference in tire pressure. We found it much simpler to drive in a relatively straight line once we made the switch to solid wheels. YMMV, or you might actually finish on time so you have time to test better code! :)

Re: Where can we find good pneumatic wheels?
 

Yes.

Re: Where can we find good pneumatic wheels?
 

That's why we switched from pnuematic, we wanted to go to 4". We used to use 6" pnuematic on all our 4WD robots but when we went to 6WD we wanted smaller wheels.

FYI Our Custom wheels and tread have 100% chance of Einstien historically as well, and 50% chance of winning the Championship... (2006-08,2010)

Re: Where can we find good pneumatic wheels?
 

How did you (everyone who has used pneumatic wheels) select an inflation pressure? I would think traction, drag and turning would be fairly sensitive to that. What kind of pressure range could you tolerate with adequate performance? How often do you check it / adjust it?

Re: Where can we find good pneumatic wheels?
 

As far as pressure goes, it does make a decided difference.
We use 6" pneumatic tires on some robots. At full pressure the robot had more tendence to bounce. At lower pressures the grip was greater.
Too low and the tire might roll off the rim when it gets pushed sideways.

With the very small volume it can be an art to balancing the pressure in all tires. You need a pump with an integrated pressure gauge that disengages without letting even a smiggen of air out. Or you develop the skill required.

Re: Where can we find good pneumatic wheels?
 

Or you have a compressor with a regulator set to your desired pressure dedicated to inflating the tires.

Re: Where can we find good pneumatic wheels?
 

When we were in skid steer mode we had a wide aspect ratio. Traction was a consideration. As the tires wore down and got stickier it was harder to turn. In the off season we put tape on the front tires to reduce traction to make turning easier.

In the past we had long aspect ration bots with skid steer. In 2004,5 our tires were about 10-12" OD. They took lots of power to turn and were not " precise". On a high center of gravity machine there was quite a bit of bucking/tipping. We started out this way in 2006 and ended up with 2 omni wheels before we shipped.

On a low CG bot the long aspect ratio configuration was OK. In the future we'd most likely go with the 6 or 8 wheel design.

Jay

Re: Where can we find good pneumatic wheels?
 

Related thread about mounting sprockets, etc.

http://www.chiefdelphi.com/forums/sh...ad.php?t=88066

Re: Where can we find good pneumatic wheels?
 

We've used pneumatic tires in 2002 and several other years but those were the best tires/wheels yet. They were small so there was little bounce, yet great traction. The fact that they were pneumatic also lent itself to correct for leaning and imperfections in the carpeted surface--four wheels were always gripping. That was the year when 71 Hammond Beatty had the crawler which dragged the two goals with the opponents kicking and fighting to the other side of the field--so traction was paramount.

Here's a link. At the time everyone made their own hub mounting plates. The following year, FIRST came out with hubs in the KOP. Two large fender washers with the holes bored out with the use of standoffs sandwiched in between worked well for many teams.

http://www.skywaywheels.com/products/caster/index.html

Re: Where can we find good pneumatic wheels?
 

Skyway

Re: Where can we find good pneumatic wheels?
 

Can anyone supply some information for me about the mcmaster wheels mentioned by 330. Part number: 2717T51 We are looking at these as a high CoF option for our drivetrain this year.

What I am looking for:
Mostly design of the stock hub/rim. Searching the web eludes to that all pneumatic casters are very similar, if not the same hub design. I was unable to find a model, or drawing.
I'm curious on what the size of the 4 bolt circle is.
Also, I am looking for the size and length of the shaft part of the wheel. (I do not mean interior dimension, but outside dimension so that you could machine a hub and and insert it over.)

Thanks in advance.

Re: Where can we find good pneumatic wheels?
 

Rims are Al, curved, with the 4-hole pattern. I think the hole pattern was on a 1.5" radius circle, but I'm not quite sure.

Not sure on shaft portion, but I do know that 330 did custom hubs. They might still have the CAD around. I'm not sure I have access to the repository anymore; you'd be better off asking one of the other 330 members.

Re: Where can we find good pneumatic wheels?
 

Can one of the teams that used the McMaster wheel (2717T51) last year please post the tire information for the tires you used for that wheel?

I'm looking to find out the manufacturer and model number for that tire. Thanks!!!


Team 1519 has had great success in the past using various pneumatic Skyway wheels. See http://www.skywaywheels.com/ Their wheels are available with various semi-custom hubs, see http://skywaywheels.com/products/hubs/index.html Discounting is available for FIRST teams, as described at http://skywaywheels.com/usfirst.htm

Last year, we used the Skyway WHL-428 (a 9"x2" pneumatic) on the front of our robot. Photos can be seen at http://www.chiefdelphi.com/media/photos/35102 and http://www.chiefdelphi.com/media/photos/35535. The tires on these wheels were an Innova IA-2817-4 with a size of 2.80/2.50-4. These had great grip and were extremely rugged.

Re: Where can we find good pneumatic wheels?
 

These tires have phenomenal traction and excellent wear! We used them all season, with heavy wear at 2 regionals + championships + IRI, and half a dozen one day off-seasons. We played into Saturday afternoon at all the competitions, but we used our twin for practice during the season, so it didn't see as much practice time. The only downsides...

They're extremely wide (in reality, they're about 3"+ at the hub)
They're quite heavy (~2 pounds each, I think)
They're 9"... good for some applications, not-so-good for many others!

We're looking at doing a 6WD this year so unsurprisingly we're looking for smaller wheels! :-) Thanks for all the links - I'm tempted by the 6" pneumatics from McMaster! Dropped center with roughtop or wedgetop tread on the corners, most likely...