Looking for drive system suggestions

Whelzorn

Ok, I have a layout for a robot that I am currently working on, and I have a few questions regarding the drive system. I have attached a pic illustrating the layout of the motors. The motors and shafts are pictured in green, and the metal body in white. The motors need to drive a wheel attached to their shaft, plus a wheel on the shafts at the opposite ends. The obvious answers would be a belt or chain, but thats where the suggestions come in. I need to know what a better solution would be: A timing belt that drives a large pulley on each shaft so that it works like a track, thus eliminating the need for other wheels, or should I have a wheel on each shaft and have a smaller timing pulley next to each wheel with a belt driving it, or the same thing with sprocket and chain instead?
Also, I would like to have a little backlash as possible so that all four wheels turn and accellerate at the same speed and time.

Thanks,
Justin W

Catharsis

From what I remember, dual sided timing belts are pretty expensive and hard to find. If you decide to use timing belts as tracks you would need to use non flanged pullies(since the timing belt will not extend past the flanges) and come up with a way to keep the belts from sliding off the pullies.

Should you decide to use wheels, I think timing belts would be much better than chains. Less noise, more efficient, easier to work with, etc. If you use the right sized belts, the wheels should turn together perfectly. Here is a very handy calculator to figure out the belt length/pulley diameter/distance needed:

http://www.sdp-si.com/Cd/default.htm

Whelzorn

hmmm... the hard part with a smaller timing belt is that the piece of metal that extends the sides outward on my design (they have a diagonal hatch on them) would have to either let the belt pass through it, or the pulleys would have to be large enough so that the belt ran higher and lower than that piece of metal. Using some sort of track would solve this, and I wouldn't need wheels and pulleys, but I have no idea what to use as a track. Double sided timimg belts are not too expensive from sdp-si, but they are at most 1/2" wide, which is a sad excuse for a track. I could use 2 on each side, but then it might get expensive. Is there any other alternative to timimg belts for use as tracks? they need to be somewhat strong, as these motors put out over 50 ft-lbs each, and could break a track that is too weak. A track width of 1.5" would be ideal, with a pulled diameter of 6", but it would still work a bit smaller.
I have no idea if something like that actually exists and how much it is, but if anyone knows, that would be great.

kelvin james

These tracks don't look too bad, maybe worth a look.

nelnick.com/nelnickrobotics/product_info.php?cPath=25_26&products_id=279&osCsid=6b507897dc910bd959ff14dafd661223

Whelzorn

those look good, I just wish they came in more widths and lengths, and perhaps had optional metal pulleys. I have seen people do things like use chain and then attach a plate to each link, but chain would have to much play for this project I think. Just for reference, my shafts are 10.5" apart on each side, so a belt or track would need to fit that distance tightly.