After watching Gravity on Sunday, I decided to do some research on full prssure systems as an alternative to the 100mm 16barg pneumatic cylinder that I had planned for my new robot. I was surprised by the weight of the equipment.

My new pneumatic cylinder and end fittings will weigh almost 8kg, and develop a force of 12.5KN at 16barg. An 80mm hydraulic cylinder (with the same 125mm stroke) and equivalent end fittings weighs over 24kg. It develops twice the force at 50barg (25KN), but weighs 3 times as much.

Unfortunately I dont have sufficient spare weight in the new design to even consider using hydraulic equipment.

Jeremy

PS. I believe that William Dijkstra used a 100mm ram on his machine, and is now reputedly going for a 150mm ram!

PPS. I would be interested to hear from any full pressure competitors whether they disregarded the limits on maximum piston speed on their hydraulic rams or whether they are all running one-off specials?