The hydraulic industry is old, but not as old as mechanical power transmission, which started thousands of years when some genius invented the wheel (that dude should be awarded a Nobel Prize posthumously, even if it would be anonymous). Electrical power transmission isn’t much younger than hydraulics, and I’d like to be clear that I’m speaking about hydrostatic hydraulics rather than hydrodynamic applications such as water mills or river hydraulics.
Electrical and electronic engineering has changed vastly since the early days post-conception. We’ve gone from crude switches operating light bulbs with twenty-hour life expectancies to micro-processors switching at a rate of trillions per second. Our world is run by electronics, and the rate of advancement is exponential. But what has hydraulics achieved in the same period?
Pretty much nothing, actually. A linear hydraulic actuator still uses a piston for compressed liquid to push against for force creation. A pump still rotates or reciprocates to push fluid through conduits and valves. The only advancements from how things were done a century ago are related to the details of the job.
Seals were made from natural materials, such as leather. Construction of components, such as valves, was with unrefined material stock and with low machining tolerance. Because of material and construction limitations, pressure in old-school machines was rather low, so the force densities of the actuators were not what they are today.
I love hydraulics, so the lack of real advancement or any kind of paradigm shift has me somewhat concerned. Most of the evolution in fluid power is with the electronic control of already existing hydraulic technologies; more of a win for electrical than for us, as far as I’m concerned. Being a mature industry, hydraulic innovation comes in minute contributions in engineering and materials, which improve performance and reliability at tectonic rate.
Perhaps my concern is misplaced, however. How perfect is the use of compressed fluid to transmit energy that advancements come by the micrometer rather than the light-year? Sure, the industry is mature, but nobody does it better! Even the championship winning, straight-A, valedictorian of world technologies, electricity, has not been able to replace good ol’ oil. Even with exponential advancement, an electric press can’t hold a candle to a hydraulic unit of the same capacity.
In the mobile hydraulic industry the gap between hydraulic and electric actuation isn’t even fair; I don’t think anyone is even predicting an electric excavator that is both potent and reliable while being reasonable in price. Hydraulics isn’t advancing much because it doesn’t have to. Why re-invent the wheel?