In the past, people utilized the forces of wind and flowing water to make certain "mechanisms" replace humans in labor.

There were ships propelled by wind power about 5,000 years ago, and waterwheels driven by the force of water flow about 2,000 years ago.

Place two electric fans side by side facing each other. Let one electric fan rotate, and under the drive of its wind force, make the other electric fan that is not connected to the power supply rotate.

The hydraulic torque converter works based on this principle.

The way the hydraulic mechanisms used in presses and excavators utilize the fluid flow force is different from the above. They work according to the principle of fluid pressure (static pressure) in "Pascal's hydraulic press principle".

Pascal's principle was discovered in the middle of the 17th century. However, it took nearly 200 years for the price of convenient hydraulic mechanisms to reach an acceptable level.

In 1882, there was a record of a double-column press using hydraulics for reciprocating motion.

By 1920, hydraulic pumps had developed to a certain level, and a reliable pressure source could be easily obtained.

Since then, using hydraulic mechanisms can not only perform simple reciprocating motions, but also freely adjust the speed, reversing time, etc., and their application range has gradually expanded to grinders, broaching machines, and drilling machines.

During World War II, hydraulic technology developed at an amazing speed. Hydraulic mechanisms and servo mechanisms were developed and adopted in an astonishing manner in aircraft, ships, and weapons.

After the war, these precise hydraulic mechanisms and servo mechanisms also extended to general industries and achieved great development.

When Pascal introduced the principle of the hydraulic press in "Treatise on the Equilibrium of Liquids", he wrote: "Fill a closed container with water and open two holes. The area of one hole is 100 times that of the other hole. Plug pistons into the two holes respectively for sealing. In this way, one person pressing the small piston is equivalent to 100 people pressing the large piston." This is what is now called "Pascal's principle".

When applying this principle to a hydraulic press, any large force can be obtained by using the relationship proportional to the piston area. Therefore, a new type of lever was developed at that time.

However, just like the functions of ordinary levers and bolts, when the small piston is pressed down by 100 mm, the large piston only rises by 1 mm. In other words, the total work remains unchanged.

Pascal also combined the problem of unchanged work with the problem of the center of gravity for proof.

The English words corresponding to "hydraulics" or "hydraulic engineering" are "hydraulics". The English-Chinese dictionary states that "hydraulics" means hydrology and hydraulics. The adjective "hydraulic" means hydraulic, water-using, hydraulics, etc., and it also takes "hydraulic press" as an example of a compound word meaning "hydraulic pressure".

In this way, "hydraulics" and "hydraulic pressure" have a deep relationship. Water is the liquid that exists in nature in the form that we can most easily utilize. When performing certain operations with a liquid, water will be the first thing that comes to mind. There is no liquid that is easier to obtain and cheaper than it.

The prototype of the hydraulic mechanism is the hydraulic press used in Pascal's experiment and its principle. It was only 100 years ago that hydraulics replaced water.

After the publication of "The Principle of the Hydraulic Press" in 1654, for a long period of about 230 or 240 years, "hydraulic pressure" was used instead of "hydraulics".

Needless to say, "hydraulic pressure" is still used nowadays. However, compared with "hydraulics", it is only used in a certain field, and the quantity used is also small, so it is generally difficult to attract attention. For example, for the forging machinery used when forming red-hot iron blocks, using oil poses a fire hazard, so hydraulic pressure is used.

The first steam engine was manufactured according to the patent of Wystan. This patent appeared in 1663.

A hundred years later, Watt invented the improved steam engine. Various improvements were made to this steam engine, and it was widely used as an industrial power component.

Before that, only waterwheels and windmills were used as power components. Needless to say, precise machine tools had not yet appeared, and even pumps or cranes were all handmade. At first, wood was used as the raw material. When wood was used as the raw material, there was no problem of rust.

From the beginning to the second half of the 19th century, various machine tools were developed, and quite perfect hydraulic pressure machines were also manufactured.

However, there are limitations to using water, such as problems of rust and corrosion, poor lubricity, and the operating temperature must be limited to 0-100°C, etc. These limitations are really troublesome.

If a hydraulic pressure machine is used for construction machinery that is often used outdoors, it will not be able to operate due to freezing in severe winter, and water must be frequently replenished due to evaporation in midsummer.

From the beginning of the 19th century to the end of the 19th century, with the simplification of the production process of high-strength steel and the further popularization of commonly used equipment, for machine tools used for precision machining, the power components include gasoline engines (internal combustion engines), diesel engines (internal combustion engines), and electric motors.

After that, a method of refining lubricating oil from petroleum emerged, and it suddenly transitioned from "hydraulic pressure" to "hydraulics".