The hydraulic press is a mechanism made up of communicating vessels driven by pistons of different areas that, through a small force on the piston with a smaller area, allows obtaining a greater force on the piston with a larger area.[1]​ The pistons are called water pistons, since they are hydraulic, this concludes with one of the most revolutionary laws.

The performance of the hydraulic press is similar to that of the lever, since greater forces are obtained than those exerted but the speed and length of movement are reduced, in a similar proportion.[2]​

In the 19th century, in France, the mathematician and philosopher Blaise Pascal began research regarding the principle by which the pressure applied to a liquid contained in a container is transmitted with the same intensity in all directions. [3] Thanks to this principle, very large forces can be obtained using relatively small ones. One of the most common devices to achieve the aforementioned is the hydraulic press, which is based on Pascal's principle. In 1795, Joseph Bramah invented and obtained a patent on this press, he can be considered the father of the Hydraulic Press.[4][5][6]​.

When a force is applied to the smaller area piston, a pressure is generated:.

Likewise on the second plunger:

It is observed that the liquid is connected, so by Pascal's principle, the pressure in the two pistons is the same. Therefore it is true that:

This is:.

Then, the resultant force of the hydraulic press is:.

Where:.