pneumatic question

[widow_twanky]

Rack and pinion might be a bit more on the expensive side than you'd like. It tends to be much easier and cheaper to make a shunt style axe like Hydra has. All works very well with standard rams with 300-400mm throw.

[team_orr]

cool, how does that work?

[daliad100]

It's a sort of four bar linkage which can be seen in this video (sorry aout the quality though) .

I have also made the linkage here (the lengths are all aproximate so have a play when designing your axe)
http://incredibots2.com/?robotID=dal...cff49.17217602

You could also try a chain based rack and pinion like the judge shown here:
http://members.toast.net/joerger/AskAaron/weapon.html
just Ctrl-F and paste this into the find box How were the chains attached to the weapon sprockets on 'The Judge' (without the speech marks).

[widow_twanky]

cool, how does that work?

As Daliad100 says it's a four bar linkage. which is designed to accelerate the speed of the arm to more than that of the ram. Probably the simplest way is to have a look at hydra and copy that. I'd suggest a bit of a bigger ram (80/100mm) and definitely at least a 1/2 port valve. When we changed to half inch valves (and finally got it working) it made a massive difference.

Flow in a 1/4 valve is about 1000l/s for a 1/2 valve it's about 4000l/s so it suddenly throws the whole arm at a much faster speed.

Andy