Printable View
The current trend with all axes at the moment is to simply take the output of the pneumatic cylinder and run it through a rack & pinion to get the swing action.
But I have always wondered why. This little beauty explains it best. [1:09 for the mechanism]
http://www.youtube.com/watch?v=PjZ7GWNzR1s
Someone with more experience will probably be able to provide a better answer, but from what I can tell/have garnered over the years;
That mechanism allowed a large axe arm stroke for a moderately short ram stroke. If you were to connect the ram directly to the axe arm, the travel of the axe would be limited. You wouldn't get anywhere near the 180º movement that Shunt gets. With the linkage mech, not only do you get that travel, but the axe arm also accelerates right through the stroke, meaning that it hits your opponent at high speed.
Why this mechanism was used so extensively in Robot Wars compared to now, I don't know. It's clear to see from the likes of Little Hitter and Thor that the rack-and-pinion method still allows a relatively short ram stroke to move an axe arm through a large radius, and that the velocity of the axe arm can be intense, so I can only assume that the rack-and-pinion method hadn't really been explored or its potential realised until later series of RW/live events. I think Terrorhurtz in S6 was the first notable instance of the rack-and-pinion mechanism being used. It also has the advantage of having less moving parts than the linkage, so less to go wrong and also allows the ram and axe to be configured within a smaller space.
Side step on the topic here but what is the normal pressure for a pneumatic system in featherweights?
Could we go up to 10bar? 12bar?