Hydraulics basics

The word hydraulics comes from the Greek words hydraulikos´ and hydraulos. The latter means water organ and is composed of the words hy’dör (water)´ and aulo's (tubes). The water organ, also called hydraulis, was constructed already in antiquity and was used well into 800 AD. It used water instead of human pump power. Hydraulics is thus based on the fluid under pressure in some form of pipe or tube. By subjecting the liquid to pressure differences in a closed system, one can get the hydraulic power of mechanical energy.
In other words, hydraulics is the smart way to transfer, store and control the energy by means of liquid. With the help of engines, pumps, hoses and valves one can achieve very high power, high efficiency and precision of energy transfer. These forces can in turn be adjusted and tamed depending on how the hydraulic cylinder will be used. Hydraulics is based on a cycle of fluid that allows you, for example, to operate the bucket on an excavator. When gases, such as air, are used instead of liquid it is called the field of pneumatics.


Modern hydraulic systems are usually divided into hydrostatic systems and hydrodynamic systems. In turn hydrostatic systems can be divided into two types. One where the liquid has a high pressure and one part where the fluid has atmospheric pressure. The liquid is transported through the ducts and valves of any type of engine and the pressure cylinder. Then there is converted energy from the pressurized fluid to mechanical energy. A hydrostatic system is common in e.g. work vehicles where the ratio of the power and weight must be very high. Hydrodynamic systems are used almost exclusively for transmissions for different types of vehicles. One example is automatic transmissions.