Hi, my team is looking at a forklift design to raise the inner-tubes from the ground to the highest shelf. What kind of thoughts do you have about an aluminum pole with a rack on the back, and a Fisher Price motor connected to a gear traveling up, with that assembly connected to a forklift inserted into the opposite side of a pole and movable up/down. Sorry if this is a little complicated to understand, I’ll try and crudely ASCII it: =|}xO, where = is the forklift, | the pole, } the rack, x the gear, and O the motor. Thanks!
Will it work, sure anything is possible. But realize that you will only have the length of your rack of extension. Is that enough to reach the pegs you are going for? Can you source a rack long enough to do what you want to do, and still not weigh a ton, and attach the pinion to the FP gearbox?
look around on www.howstuffworks.com and the like for examples of how a forklift, crane, elevator, etc. work this may give you more ideas, or help to refine your own.
If my understanding of what you are saying is correct, then my team used this design back in 2005 when lifting tetras for the game Triple Play. It’s definitely doable.
So I think that a fork lift can take its ideas from an elevator:
http://www.saasacorporation.com/images/pg_elevators_Lift_archt.jpg
Its just a motor that just pulls the the chain up and down. Here is a rough sketch:
http://img713.imageshack.us/img713/923/liftm.jpg
What kind of speed were you looking at for a bottom > top travel?
Heh! 1276 built exactly this robot in 2007. Take a look, and I can answer any questions. 
Hey, thanks for replying. What kind of speed were you looking at for complete up/down travel, and what kind of difficulties did you have with the engineering?
Pretty broad question Batman!
Don’t remember honestly. It was fairly quick… but not dangerously so. You could probably calculate it from watching the match videos. A 3 second traverse of the tower perhaps? (so about 2 feet/second).
We had a lot of fabrication difficulties. If I were to do it again, especially without access to such a great aluminum welder, I’d do it with a square tube mast. If you used a cut up belt, you would save yourself a lot of machining time (especially if you don’t have your own equipment). The hinge is important. Ours was not strong enough, so we ended up just pinning the tower at 6 feet tall. If we had planned to make the hinge strong from the beginning, we could have left it actuated. We had to use a junky piano hinge from the hardware store McMaster sells much more substantial ones. There are big shock loads as it comes upright.
As you can see from the last picture in the gallery, you can literally do this with a cut up belt, pulley, and 2x4.
What about a lead screw?