[Jedi Padawan]

Pnuematics barring leaks and other snaffoos (sighs at two years ago's robot that leaks like a spaghetti strainer) should hold thier position as long as they have the particular valve (forget which one it is) two have a spring return and the 3rd uses air power to turn on and air power to return that would be the one you'd want to get if your objective is to stay after time is called.