Hydraulics

Hydraulics is the science of using liquids to create force. When you push on a liquid in a closed system, the liquid pushes back with great force. This is how hydraulic machines work. They can lift cars, dig holes, and even stop airplanes. Hydraulics makes many powerful machines possible.

How Hydraulics Work

Liquids cannot be squeezed into a smaller space. When you push on one end of a liquid-filled tube, the force travels through the liquid to the other end. If the tube is wider at the other end, the force gets multiplied. A small push on one side can create a big push on the other side.

Hydraulic Machines

Many machines use hydraulics. Car brakes use hydraulic fluid to press brake pads against the wheels. Excavators use hydraulics to move their powerful arms. Barber chairs go up and down using hydraulics. Hydraulic jacks can lift entire cars so you can change a tire.

Fun Facts

• A hydraulic car jack can multiply your pushing force by more than 50 times.
• The brakes on an airplane use hydraulic pressure to stop the plane on the runway.
• Hydraulic systems were used in ancient Rome to power fountains and water mills.

Did You Know?

The basic idea behind hydraulics was discovered by a French scientist named Blaise Pascal in the 1600s. Pascal's law states that pressure applied to a liquid spreads equally in all directions!