Hydraulic technology has been helping people work for thousands of years in its various forms. Early use of water to power our world saw the discovery of the watermill, using the hydrodynamic properties of water to turn a water wheel. Water-powered technology offers methods to increase our capacity to process anything from flour or paper by grinding raw materials such as wheat or wood respectively. This early hydraulic technology paved the way for our development and use of fluid power technology as we know it today.
Today’s hydraulic systems continue to permeate our daily lives, and even despite widespread electrification, fluid power technology has only increased. However, hydraulics offers an advantage not replicated with any other technology, and that advantage is power density. No other source of motivation creates as much force in such a small space as hydraulics does. Hydraulic pumps, motors and cylinders — along with associated control and conveyance technologies and components —ensure powerful, reliable, and durable lifting and pushing motion throughout mobile machinery, industrial machinery, aerospace, and more.
Modern hydraulics run 3,000 psi all day, with more powerful systems approaching 6,000 psi or more. With such energy compressed into relatively small spaces, hydraulics offers a level of force not possible with any other technology. Hydraulic machinery powers the construction equipment used to build roads and cities while providing the motivation to plant and cultivate most of the farmland in the world. If you can think of a machine that moves while achieving useful work, it’s likely powered by hydraulics.
To exploit hydraulics does not require a machine to operate on tracks or use closed-loop drive systems like much of the mobile machine industry. In fact, simple machines and objects use hydraulics to perform myriad tasks for various industries. For example, the machine tool industry uses small hydraulic power units to operate the clamp or chuck on CNC mills and lathes, while any large aircraft counts on hydraulics to operate its primary flight functions. Even the simple bottle jack used to lift your car to install new wheels takes advantage of the high power of compressed liquid.
Hydraulics and pneumatics are both subsets of fluid power, but hydraulics differs from pneumatics in that the former uses liquid to transmit force. At the same time, the latter conveys force using compressed air. Suppliers may manufacture hydraulic fluid from base stocks of mineral oil, synthetic oil or even water-glycol solutions. The most common fluid in hydraulics is anti-wear oil derived from crude, while premium blends come from completely synthetic base stocks such as polyol esters. For applications requiring fire resistance, fluids must not be capable of supporting flame; otherwise, a hose may mimic a flame flower should it spring a leak in the presence of extreme heat. Therefore, such fluids usually have a water base, like high-water-based fluids or the aforementioned water glycol.
Naysayers may argue that hydraulics is dirty, loud, or environmentally unfriendly. However, that lazy argument doesn’t ring true for fluid power engineers. Those claims merely indicate that the described systems are improperly designed, installed or maintained. Combining electric and electronic technologies with hydraulics compliments a machine in many ways. Efficiency increases while maintaining power density, and the sophisticated electronic controls systems pair well in the control of electric-proportional valves, especially when paired with sophisticated transducers.
Understanding the operation of and parameters for the application is critical, as is good working knowledge of sealing and contamination control technologies. Even the practice of adding a new component to your system may introduce contamination. Contamination destroys hydraulic components more frequently than any other cause, so you must put fluid conditioning technology at the front end of your machine design. Failure and downtime will plague your machine without the appropriate filters and coolers to keep hydraulic fluid within its ideal operating condition. The bottom line is that intelligent engineering and mindful maintenance will avoid problems in the future.
Filed Under: Engineering Basics