[EricH]

Originally Posted by squirrel

Hydraulics use liquid to transfer power. The liquid doesn't have to be oil, does it?

You aren't volunteering to check that every robot at an event has the proper liquid, are you? If it involves removing a sample from the robot, I don't think I want to be involved--it's under pressure, usually (well, OK, it's trying to move, not necessarily under pressure).

Aside from hydraulic components eating up the weight limit, the mess factor (present regardless of liquid), and the problem of another 5 pages in the already-massive rulebook (and 50 posts asking about them on CD)...Well, I don't see a problem other than those few.

Actually, come to think of it, if you replace "liquid" with "fluid", pneumatics are hydraulics.