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Hydraulic systems transmit power by utilizing the pressure of fluid within a sealed system. The brakes on cars and trucks, wheelchair lifts, hydraulic jacks and wing flaps on aircraft typically employ hydraulic systems. Many manufacturers use hydraulic systems because they have many advantages over mechanical and electrical systems like offering up a lot of power in a small space, but if the fluid leaks from the system, this creates a problem and a disadvantage in the system, in that it won't work at all.

#### TL;DR (Too Long; Didn't Read)

Advantages of hydraulic systems include power, accuracy, efficiency and ease of maintenance. But they disadvantages too: they can leak, which makes them messy, and the fluids inside them are often caustic to paint and some seals.

## How Hydraulic Systems Work

Hydraulic systems use liquid to create pressure. Liquid particles are close together, meaning a liquid is almost incompressible. When the particles move, they strike each other and also bump against the walls of the container. Because the pressure in a liquid transfers in equal measure in every direction, a force applied at one point on a liquid transfers to other points on the liquid. You work out the pressure using the equation F ÷ (P x A), where P is the pressure in pascals, F is the force in newtons and A is the cross-sectional area in meters squared. This is known as Pascal's law.

In hydraulic systems, a small force across a small cross-sectional area transmits pressure and creates a large force over a larger cross-sectional area. Essentially, if you connect two cylinders, a large and a small one, and apply force to one cylinder, it generates equal pressure in both cylinders. Because one cylinder contains a larger volume, the force the larger cylinder produces is higher, although the pressure in the two cylinders remains the same.

## Hydraulic System Examples

A hydraulic system most every driver uses every day, without thinking about it, is the brake system in your vehicle. Other examples include lifting equipment, such as hydraulic jacks and wheelchair lifts, lifting and excavating arms on backhoes and other heavy equipment, hydraulic presses, which produce metal components, and some parts of aircraft and boats, including wing flaps and rudders. Every hydraulic system follows the same basic principle. For example, a hydraulic jack lifts heavy loads with a pump plunger, which moves oil through both cylinders. Pulling the plunger back opens a suction valve ball and takes the fluid into the pump chamber. Pushing the plunger forward sends the fluid into an external discharge check valve, then into the cylinder chamber, closing the suction valve as it builds pressure inside the cylinder.