pic: Pneumatic

[K.Porter]

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[Smaug]

what kind of air motors are those and are the cheep?
my friend and i want to experiment with those before build season

[Nuttyman54]

I cant' help but notice how little chain wrap you have on the drive sprockets. did you experience much chain slippage?

[K.Porter]

Actually, chain slippage was one problem that I didn't have with the chains.
If you notice the front axle's connection to the frame in that picture, I've milled some simple slots for the bolts as a basic chain tensioning system. I just pulled the chain taught with the whole axle assembly before tightening the bolts. That tension kept everything pretty well in place.
One problem I did have with the chain, though, was that the added tension would attempt to pull the wheels slightly out of line with each other (there's a little bit of slop between the wheels and axle, allowing that movement) Occasionally this will get to the point where the chain will jam slightly on the wheel sprockets, but it's a minor problem.

As for the air motors, I found them in the back room of my school's technology classroom. The only information printed on them is "Gast Mfg. Corp." but looking at their website, the exact model seems to be out of production. As for cost, I really have no idea. Gast doesn't even list anything on their website for current models...

[Qbranch]

Checked on McMaster... the prices range from $135 (team numbers in everyday places ) to $972 .

One major major advantage to these motors is that in a low torque application requiring super high rpm such as engraving or micro-machining, these things rock... the cheapest air motor has a top speed of 10,000 rpm at 90psi, 18cfm... we used these at the place I work to do some engraving 1/32" ceramic end mills.

Well... I have a question about your robot too... how fast did it go? did you have variable speed? was it reversable? if you had variable speed, how'd you do it?

-q

[K.Porter]

How fast did it go: Well, I don't have a number for you (sorry) but: pretty darn fast, at least relative to the other vehicles it competed against. It could cover the 3 feet to the end of the table in under a second.

As for variable speed...yes and no. We basically used the main air valve for control (turn one way, go faster, turn the other slow down. Primitive yes, but it works.)

And, in theory it was reversible. Since I ran out of time to work on it, I couldn't finish my solenoid control box. I was planning on running a tether line to each of the four motor inputs (you can see the two un-used tubes in the picture) and then using the solenoids to reverse the flow to either motor, in order to turn or reverse. I prototyped the concept, but simply didn't build the control unit...

[robostangs548]

Looks nice, how did it do?