Let Hydraulics Stop Your Car!

Hydraulics is a branch of engineering science which is concerned with the mechanical properties of liquids and the general power of fluids.

It is also focused mainly on the engineering uses of fluid properties. Hydraulics, therefore, derived its theoretical foundation fluid mechanics. Hydraulics spans a vast scope of topics, ranging from science to engineering disciplines.

Among the concepts it covers include dam designs, turbines, pumps, circuitry, pipe flow, hydropower, river channel behavior and erosion.

Machineries using the principles of hydraulics include bulldozers, backhoes, forklifts, cranes, and shovel loaders. Hydraulics is also the reason why we see cars being lifted in service centers so that technicians can work beneath them.

It is also because of this same technique that elevators operate. Airplane surfaces are operated and controlled by hydraulics, and even the brakes in our cars use hydraulics.

The idea behind hydraulic systems is simple. It states that force applied at a point gets transmitted to the next point with the use of an incompressible fluid, which is usually a type of oil. In the process, the force is being multiplied.

In a simple hydraulic system, two pistons are connected by a pipe which is filled by oil. These pistons are installed into two glass cylinders which are filled with oil. The glass cylinders are then connected to each other by a pipe filled with oil.

When force is applied to one piston, the force is transferred to the next piston through the oil in the pipe. Because oil cannot be compressed, the efficiency is very good because all of the force applied shows in the second piston.

The pipe which connects the cylinders can also come in any length, shape and size, so it can bend, twist, or turn through all the things separating the two pistons. This pipe can also be a fork, which simply means that one master cylinder can drive one or more slave cylinders.

In hydraulics, it is very important that the system eliminates air bubbles. The presence of air bubbles in the system affects its efficiency as the force being applied to a piston compresses the air in the bubble rather than transferring it to the second piston.

The brakes in a car are the simplest example of piston-driven hydraulic system. As the brake pedal is pressed down, it pushes the piston in the brake's master cylinder. This action drives four slave pistons to push the brake pads towards the brake rotor so the car stops.

The force coming from your leg is not enough to stop the car, so car multiples the force. This is called hydraulic multiplication. In most cars today, there are two master cylinders driving two lave cylinders each.

This design allows the car to brake or stop even if there is problem in the first brake, or if there is an oil leak. In other hydraulic systems, valves connect cylinders and pistons to a pump which supplies high-pressure oil. The valve applies forward and backward force to the pistons.

You can see large hydraulic machines in construction sites. These machines, driven by hydraulic power include excavators, skidloaders (also known as the "bobcat", because it was the name given by its first manufacturers), and dump trucks.

When you see these machines, remember that despite their enormous sizes, the common force driving them comes from hydraulics.

James Monahan is the owner and Senior Editor of HydraulicZone.com and writes expert articles about hydraulics.