The Hidden Forces: Uncovering the World of Hydraulics and Pneumatics

Have you ever taken a moment to think about the invisible forces that create our modern world? Whether it's the brakes in your automobile or the robotic arms that build our gadgets, these two amazing technologies are always at play: hydraulics and pneumatics. These systems utilize fluids (liquid for hydraulics, gas for pneumatics) to assist a multitude of machines that make our lives easier, safer, and more productive.

A Simple Introduction to Fluid Power

• Hydraulics and pneumatics can be grouped together under the larger heading of "fluid power." These systems all contain an enclosed fluid to do work and transfer motion.
• Hydraulics - Uses an incompressible liquid (most commonly oil). Because liquids cannot be squished, they can transfer force very effectively. Think about a solid rod pushing something: it provides a force to move an object, only the rod cannot bend like a liquid can.
• Pneumatics - Uses a compressible gas (most commonly air). Because air can be squeezed, this allows pneumatic systems to have a softer, cushioned action. However, pneumatic systems generally operate at lower forces compared to hydraulics.

Where do we see hydraulics in use?

• Hydraulics is all about power and precision. If you want controlled power to lift, push, or pull something heavy, hydraulic systems can be the answer. 
• Heavy Equipment Used in Construction - Excavators have massive arms that use hydraulic cylinders for power. Bulldozers have blades powered by hydraulics. Cranes use hydraulic mechanisms for lifting.
• Automotive Systems - Brakes in your car, for instance, use hydraulic fluid to transfer the small force from your foot to the brake calipers. This ultimately causes a multi-ton vehicle to stop. Power steering also often uses hydraulics, so you can turn the wheel with ease.
• Airplane Landing Gear - The huge weight of an airplane is raised and lowered with hydraulic systems, so the plane rides along the ground and lifts the heavy weight.
• Industrial Presses - Forging metal, stamping out parts, or molding plastics can apply thousands of tons of force with hydraulic systems.
• Elevators and Lifts - The most common types of elevators and vehicle lifts use hydraulic rams. 

Why Hydraulics? You can get high force, control, rigidity, and the ability to transfer power over distance. 

Where Are Hallmarks of Pneumatics Found?

• Pneumatics excels at jobs that need speed, cleanliness, and some cushioning. Since air is abundant and goes to waste in the atmosphere, pneumatic systems are generally easier and cleaner as the working medium.
• Manufacturing and Automation: Pneumatic actuators are commonly found in robotic grippers, clamps on assembly lines, and sorting in an automated process, among others, that require rapid, repetitive movement.
• Dental Drill: The high-speed rotary motion of a dental drill is actuated by air.
• Jackhammers and Air Tools: Pneumatic, impact force jacks (e.g., wrenches, jackhammers) in construction provide power from air.
• Food and Pharmaceutical Processing: Pneumatics are ideal in a scenario requiring a hygienic environment, as air is clean and non-contaminated (with filtration).
• Transportation: Pneumatics are used in vehicles such as air brakes on trucks and buses, and for opening and closing on trains. 
• Reasons for Feeling Pneumatic: Speed, safety (air is safer than oil), cleanliness, simple operation, and temperature changes.

The Dynamic Pair: Complementary Technologies

Although hydraulic and pneumatic technologies are different, they can also be complementary to each other.  For example, a construction site may have large hydraulic excavators doing the heavy and slow digging, while pneumatically powered tools perform lighter and faster work.  Or in a factory, workers may use hydraulic presses to perform heaving forming and pneumatic grippers to lift lighter, more delicate parts.

Both systems utilize force and motion based on the basic principles of fluid dynamics while helping our world operate more smoothly, safely, and economically.  The next time you see something moving powerfully and being controlled, take the time to appreciate the quality hidden genius of hydraulic and pneumatic technologies.