Theemile wrote:
~80% of my 1984 Dodge Charger's control systems (gauges, sensors, and controls) were pneumatic (either vacuum or pressurized) and my '78 Honda was just shy of ~95% (Vacuum powered brakes totally suck when the master hose collapses - thank god it was a stick). These controls usually included the carburetor, emissions controls, gauges. Before the mid 80's only a handful of items on cars were "fully" electric.
The German ME-163 Rocket plane had a Pressurized air tank to power it's flight controls. There were instances where the pilot had run out of air pressure and lost control of the aircraft prior to (or during) landing if he had been maneuvering too much.
I saw a documentary several years ago, where the last surviving steam shovel used to dig the original Panama Canal was discovered in some Minnesota woods, where it had been rotting for ~20 years. They spent 2-3 days replacing some steam lines and chipping the worst of the rust - hitched a Sull-air industrial compressor trailer to it, connected the air lines, and drove the shovel out of the woods using it's own tracks (notice, no one trusted the steam engine...).
These "Large" Bucyrus Steam Shovels were about the size of a medium sized backhoe today, but we're still talking about something weighing 10+ tons, so along with everything else, yes, a pneumatic tank is 100% possible.
Very light, low power applications, air works well. Everything else? No.
Historically, the only reason air was used is because water seals could not be made. Still can't and who would ever want to use water as it rusts everything it touches and is a poor lubricant. When someone got a very basic idea and implemented it, using oil, it changed history. An oil seal, unlike a water or air seal is very simple and easy to create.
Air/cable systems are abysmally bad. Horrendous amounts of maintenance is required and when cables break, is VERY dangerous. Why the entire world sprinted, to hydraulics as fast as possible as well as being more energy efficient as well as lighter and less maintenance required.
The only downside to using oil over air or water is that a fine mist of oil due to broken pumps, lines, or hoses, can cause fires. So, you trade off the possibility of a fire for efficiency. This is solved by the expediant use of a shield around the exhaust of ICE engines or main hydraulic compressors in manufacturing centers. It should be noted that air tools/systems, also coat the entire work place/tool/parts in an oil mist as oil is mixed with the air as a lubricant. Without said lubricant the machines die quickly.
Hydraulic tools are quieter and warmer to hold as well. They also happen to have higher power densities than air tools with higher torques. The downside? Hydraulic hammering as oil is incompressible and a damper must be installed.
What is new, no perfect source for power. Who knew, there is no magic elixir.....