Top Ten Benefits Of Hydraulic Jack

A jack is a very common mechanical device to lift heavy weights or to apply great forces. While mechanical jacks uses screw thread, hydraulic jacks use hydraulic cylinder to apply very high liner forces.

The most common use of this mechanical jack is for lifting heavy equipment. These jacks are used as a car jack, floor jack or a garage jack for lifting vehicles for its proper maintenance. While ordinary car jacks use mechanical advantage to help lift a vehicle for maintenance, more powerful car jacks use hydraulic cylinder to provide capacity for lifting higher loads over a greater capacity. These jacks are rated on the basis of maximum lifting capacity and generally mentioned in tons i.e. 1.5 tons, 3 tons etc.

The operation of hydraulic jacks works on the basis of a physical principle that is better known as Pascal’s principle. This principle is named so because the French scientist, Blaise Pascal, first propounded it. This principle states that the pressure in a closed container is same everywhere, at all points of the container. Therefore, if you have two cylinders, one small and another large, connected together through a pipe, the pressure in the bigger cylinder would be the same as in the smaller cylinder. Pressure is defined as Force divided by area. Applying a small force on the small cylinder, pressure is created. By Pascal’s principle, same force would apply on the surface on the larger cylinder too. Therefore, larger force would be created in the larger cylinder because of larger area of the bigger cylinder, providing large mechanical advantage. With higher ratio of two cylinder sizes, the mechanical advantage would increase accordingly.
A Hydraulic Jack is simply two cylinders of different sizes connected together by a pipe.

This would be more clear if consider an example. Assume there is one cylinder having fitted with a piston of one square inch area and there is another cylinder fitted with a piston of size ten square inches and they are connected together by a pipe. Now, we apply a weight of 1 pound on the cylinder of the smaller cylinder. This will create a pressure inside the smaller cylinder. By the principle of Pascal’s law, same pressure would also applied on the piston of the larger cylinder. Now, piston of the larger cylinder is ten times bigger in area. Therefore, the larger cylinder would be able to lift a weight of 10 pounds.

Therefore, hydraulic jacks provide very high mechanical advantage in lifting heavy loads by using only a small force on the smaller cylinder.

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