{"id":2902,"date":"2024-03-07T09:05:07","date_gmt":"2024-03-07T08:05:07","guid":{"rendered":"https:\/\/www.bf-hydraulik.com\/encyclopedia\/hydraulics-fundamentals\/"},"modified":"2026-04-15T11:54:07","modified_gmt":"2026-04-15T09:54:07","slug":"hydraulics-fundamentals","status":"publish","type":"encyclopedia","link":"https:\/\/www.bf-hydraulik.com\/en\/hydraulics-fundamentals\/","title":{"rendered":"Hydraulics Fundamentals"},"content":{"rendered":"\t\t
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Hydraulics Fundamentals: Transmission of Forces via Fluids<\/h1>

Hydraulics is the transmission of forces using fluids. It utilizes the property of fluids that they cannot be compressed. When a closed system filled with fluid is pressurized, this pressure is distributed equally throughout the entire system. This is the fundamental difference from pneumatics, the transmission of forces through gases. <\/p>

Hydraulics Fundamentals: The Basic Principle<\/h2>

The hydraulic cylinder<\/a> or linear actuator is only one of many components of hydraulic system<\/a>s. However, its example provides a good illustration of how this technical principle works: <\/p>

When two hydraulic cylinders are connected via an oil-filled line, the following occurs: If the piston rod of one cylinder is pushed in (thereby making it the “master cylinder”), the other piston rod (of the “slave cylinder”) extends. If the piston rods of both cylinders have the same cross-section, this movement is absolutely uniform: the slave cylinder moves at the same speed and distance as the master cylinder is moved. <\/p>

However, if both cylinders have different cross-sections, the movement is no longer absolutely uniform. Nevertheless, the movements of the piston rods are proportional to each other, depending on the displaced volume. The volume displaced by the retracting cylinder is absorbed by the extending cylinder. <\/p>

Hydraulics Fundamentals: Force Amplification Through Different Cross-Sections<\/h3>

If a narrower piston rod retracts into the hydraulic system<\/a>, a piston rod with a wider cross-section will not extend exactly the same distance. However, since the pressure does not change, the force is increased accordingly. The force increases proportionally to the area: a circular cross-section with doubled radius has four times the area. Accordingly, the force at the slave cylinder becomes four times as great as the force applied to the master cylinder. The force amplification acts exponentially to the difference in cross-sections. <\/p>

Basic Components of Hydraulic Systems<\/h3>

A simple hydraulic system<\/a> therefore consists of:<\/p>