OK folks, thanks for all your input. Things are getting a bit too theoretical though.
The utube syringe powered crane is an impressive "school science project" and not very practical for a 730mm LOA tug.
The technical theory is way above my head and I always thought Pascal was a computer language or something you sucked
(or is that a Pastille?).
No offense meant to the brainy but I'm a basic nuts and bolts, bodge tape, kind of guy.
All I'm after is an
"off the shelf purchase idea " (but not costing a fortune) source of power, air or liquid, I'm not fussy but something small, neat, 12 volt, guessing 40 psi, which I can couple up to the bits and pieces of my RC retractable U/C I've got.
Thanks, Paul.