In my last blog, I discussed five applications where you shouldn’t use hydraulics. Tiny robots, cars, tight budgets, can crushers and bicycles are all terrible uses for hydraulics. On the opposite pole are the applications I feel are fantastic for hydraulics, and my top 5 are as follows:
1. Underwater. As it turns out, the same materials and techniques that can keep 3000 psi of hydraulic fluid contained within pumps, motors, cylinders, valves and plumbing, are also sufficient to prevent water from penetrating. Fluid connections strong enough to prevent bypass or leakage to the external environment won’t even break a sweat should even a thousand feet of water be exerting its yawn-worthy 433 psi.
It’s not just the pressure rating of hydraulics making it a good option for underwater applications; the mechanical nature of hydraulic motivation means no electricity is required for operation. Although underwater electronics have been quite reliable for some time, it’s more difficult to create large amounts of force with electric actuators, especially of the linear type. For the most part, any mobile machine could operate under water should you provide its engine with a snorkel for air ingestion.
2. Filthy environments. Just as a hydraulic system is impervious to water, it is generally impervious to dirt, oil, sludge or even cow pies. There is a long list of chemicals also no match for the cast iron, steel and aluminum of the typical hydraulic system, and the typical synthetic rubbers compounds used for hydraulic hose are generally very good at resisting most chemicals.
Should you find yourself in a particularly nasty environment with exposure to compounds not friendly to standard hydraulic seals and materials, special seal and plumbing options are available. Viton, Teflon et al. work great for internal seals, but you can also get chemically resistant materials for the outer carcass of hydraulic hose, and there are few environments where there isn’t an answer regarding material compatibility.
3. You want to move a mountain. No surprises here. Up to and including today, I’m aware of no other technology able to move so much mass or create so much force as hydraulics can. Could hydraulics lift a mountain? If I were to choose one actuator this side of a nuclear bomb, it would be hydraulics.
Because of the force intensifying ability of hydraulics, many molecules from a small pump can be packed into a very large actuator. This energy multiplication can result in 10,000 psi or more of force available, and cylinders the size of a thermos can extend with 30,000 lb of force; beat that skeletal muscle!
4. Where there is no electricity. I’ll be honest, if hydraulics were developed tomorrow, it wouldn’t stand a chance. Electrical machines make great sense in so many ways, nobody would invest in hydraulics, what with its weird oil power and all. Luckily for us, the machines of yore had little or no access to electricity, and the best way to power machinery was with hydraulics.
Some machines used mechanical drives, but there was little or no versatility or control. Hydraulic valves allow for control over force, velocity, acceleration and direction, all with no need for electrical control. Tractors, construction machinery, mills and other places with available mechanical input could use hydraulic pumps to power myriad machines for nearly any purpose; beat that skeletal muscle!
5. You want to impress your friends. If you, like me, have spent time in your garage standing on a hydraulic floor jack while you pump yourself up, and then “meter-out” yourself down, then you know it’s good for hours of fun. You can explain to your friends how a tiny piston being pumped by the handle is sending fluid to a larger piston on the jack, enabling puny skeletal muscle to lift thousands of pounds (of car, not person). Okay, so maybe your friends won’t be impressed. You win this round skeletal muscle.