High torque that can be purchased.

[gburlison]

We achieved 1600:1 reduction by replacing the output shaft of a 256:1 banebot planetary with a modified 8 tooth stem pinion mated to a 50 tooth toughbox output gear. Not an off the shelf solution, but very compact package as we also incorporated an encoder mount to measure the angle of the arm.

[Garret]

I am just throwing this out there, but my team used cable to actuate the arm on our elevator. The idea is based on how cables are used on weight lifting machines to translate rotational motion into linear "lifting", we just do the inverse in our system.

We found it simple and relatively easy to set up with minimal precision work (my team uses a bandsaw and a drill press only). It is nice because you can basically have as much torque as you want by just changing the point where the cable attaches to the arm and/or the position where the cable "pulls the arm from". With cable you can either power the up direction only, down direction only, or power both.

It may not be ideal for the arms of the length you are talking about but it is an easy to implement and reasonably effective solution.

I have included a picture that shows what we did. It was implemented at the last minute so it was not at all refined, but it was quite effective. I don't know if this is useful, I just thought I would throw it out there.

[qnetjoe]

Our team used a two RS-775s with Cim-u-lators and a 64:1 P80. This was connected with 10:1 (12:120) final sprocket drive and worked great.

In the off-season season we will work with some gas struts and perhaps some springs, so we can increase the speed of our arm.

For reference you can see a pic of our bot here:

http://www.chiefdelphi.com/forums/sh...highlight=3320

[Ether]

Originally Posted by qnetjoe

Our team used a two RS-775s with Cim-u-lators and a 64:1 P80. This was connected with 10:1 (12:120) final sprocket drive and worked great.

That puts max power of the 775's at around 61 degrees/second rotation of your arm. That's certainly about where you want it. And the 120:12 sprocket reduces the torque on the P80 by a factor of 10. Nice design.