Have you ever thought of a hydraulic machine? Hydraulic machines are now all over, but… How does the system work?
For instance, when you visit a construction site you will encounter hydraulic machines such as cranes, shovels, bulldozers, forklifts, loaders and backhoes.
Hydraulic machines are also in our homes in the form of log splitters and the operation of the clutch of your car. The list of hydraulically operated machines is endless; talk of the brakes your beautiful car and elevators. The most important thing that you need to note at this point is that all hydraulic machines operate on the same principle.
In this article, you will be able to understand the basic principle used in the operation of hydraulic systems.
The basic principle used by hydraulics is that of transmission of pressure in fluids. The pressure is created when force is exerted at one point and then transmitted equally to another end.
The transmission medium is an incompressible fluid. Force applied on one end is transmitted to the other end in such a way that it increases in the process. In most cases, the fluid is some form of oil.
For the sake of our discussion, let us take a look at a simple hydraulic system. This system has the following features;
- Two pistons
- The pistons are connected by a pipe filled with oil
How does the system work?
A downward force must be applied to one of the pistons, say the one to the left side. The force exerted on this piston is then transmitted to the piston on the right side via the oil medium.
There will be no loss of force because the fluid used here is incompressible and therefore efficiency in hydraulic systems is very high. It is worth nothing that the pipe connecting the pistons can take any shape.
In many hydraulic systems, the pistons are of different sizes. This is very crucial because pressure multiplication, especially on the load piston is critical. Just to elaborate on this concept of pressure multiplication, the effort piston where the initial force is applied has a larger area than the load piston. As a matter of fact, the load piston could have an area of say seven times the area of the effort piston. The load piston is the one that does the work.
Let us take an example of car brakes. The moment you step on the brake pedal, the piston in your master cylinder is pushed down. On each wheel there are slave pistons which then actuate in a manner that presses the brake pads in a counter direction to the brake rotor and then the car stops.
Another simple example is the clutch system of a car. This system has two pistons embedded in cylinders and then they are connected by a small tube. In the event that some force is applied on the clutch pedal, the piston on that particular cylinder (master) compresses the fluid and the generated pressure is then transmitted to the other cylinder (slave). The force on the slave cylinder then pushes the clutch on.
The reason why pressure is amplified on the smaller piston is because pressure, force and area are related in the following manner; Pressure=Force/Area.
Therefore, if the same force accts on a smaller area, then the pressure generated will be greater.
For this reason, the load piston has a smaller area so that the pressure generated is equal to the task to be handled.