How Hydraulic Jacks Function

Many of us have often wondered how some technological advancements like a hydraulic jack work. The secret is simple and has nothing to do with complex mechanisms. This device, as many other, work on the basis of Blaise Pascal's Principle that in a closed container, the pressure at all points is the same. Mathematically pressure is described by Force divided by Area. This means that if you have two connected cylinders - a large and a small one and apply some force on the second one it will result in a pressure, and since it is the same at all points, the large cylinder will be under the same pressure.

Hydraulic jacks use that principle and work with the force that the larger container emits and because it has greater area, the produced force is greater as well. It turns out that if there is big difference in the areas of the cylinders used, the potential force output of the bigger one will be much more powerful. Therefore, this device is constructed in a very simple way - two connected cylinders and the answer to how it works is leverage. The pressure described above is a result of the following - the cylinders are full with fluid under pressure that exert that same pressure through its own volume and against the surface of the cylinders containing it. This compressed fluid is typically oil, because it lubricates the system and is forced to the cylinders with a plunger. As it comes up the liquid goes through a valve pump. As the plunger goes down it sends the liquid to another valve into the cylinder.
Hydraulic Vehicle Automotive Moving Jack Dolly

This is the reason that these devices can generate great amounts of force while applying a small force to it. If a small one square inch piston applies a one pound weight to a hydraulic fluid, it will provide a pressure of 1 pound per square inch. In addition, if a larger container is in contact with the small one and has a piston area of 10 square inches it will have the force of 10 pounds to lift a heavy object with the big piston.

Floor jacks for instance, are used in almost any industry and as their name suggests they are positioned on the floor - you can see them in the automobile industry, they can lift a building to replace foundation as well, using a pump arm to lift things. This type of jack needs a solid ground for maximum stability and it can lift tremendous amounts of weights between 2 and 20 tons.

Some of the great inventions like the hydraulic jacks are built in a very simple way and follow simple rules, but they truly work wonders.

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