Forklift Dilemma

[mrmummert]

Hi...

This is Mr Mummert from 1610...We used a forklift in 2007. As some might recall we went to the finals with it (we lost by 7 points and because one of our alliance partners could'nt get on the ramp)

Anyway we used a outer lift tower made from 30x30 aluminium and a inner tower made also from 30x30 aluminium. We also used the slides with it. The outer tower had the slides fixed at the top between the two towers and the inner tower had the slides fixed to the inner tower at the bottom. We used No. 25 chain to move it up and down. The chain is in a closed loop. The chain was fixed to the bottom of the inner tower on the back side of the 30x30. It ran over two 18 tooth browning gears attached to the back side of the outer tower. We modified the Fisher Price gear box to drive the chain on a 20 tooth (I think its 20 tooth) gear at the bottom. The gear box is attached to a inner frame rail (30x30 again) and it drives a small chain that in turn drives two 18 tooth gears at the bottom.

To move the arm and claw up and down we made a 12 x 12 panel that is bolted to two pieces of 20x20 aluminium. The 20x20 has one sided 30x30 slides at the top and bottom on each peice. These in turn slide up and down on the inner tower. It moves up or down when the inner tower goes up or down as the panel is connected to two cables. These cables run over two 3 inch pulleys attached to the top of the inner tower. These are anchored to the body of the robot at the top of the tower braces behind the lift tower.

You can see pictures and video of it at our web site (look at the VCU regional team list and you see us there and click on our web link) We are
building a improved version of that robot for this year. We had some issues
with the arm and claw and will improve on it. It was one of the better tube
placing robots that year. One thing to remember about a Forklift design
is the high center of gravity when the lift is up. We were tipped I think three
times that year at VCU. (once when 843 pushed us over in the finals and was disqualified) So you have to be careful.
We used limit switches along the tower that stopped the driver from going up too far and doing damage to the tower
or motors.

[liam.larkin]

I most echo Tom Line's suggestion. We have used spectra cable for a number of years for various types of towers and forklifts. As he points out be wary of sharp corners but that can be done. Run the spectra through pulleys and youll be fine run it on a drum maybe powered by the barbimotor/gearbox. We have used this before as well with great success. Spectra comes in many different flavors and you should be able to find one for your needs.

Good luck

[JCharlton]

I've become a big fan of round urethane belting. It's light, cheap, and easy to make the length you need. That length can be designed so you slip instead of stalling the motors, which believe me, is a good thing.

The only disadvantage is finding the pulleys, but if you have a lathe you can easily make your own.

Another cool trick is making a "quarter-drive", two shafts at 90 degrees separated by a couple of inches or more. We used this is 2009 and it worked great on our ball-conveyor (the "series of tubes").