Hydraulics and Hydraulic Tools


What do you know about the hydraulic jack in your car? Test your knowledge against the details given in this article.


The Simplest Car Accessory – Hydraulic Jack

You must have used the jack many times for lifting up your car. Do you really know how it works? You would also have seen your car being lifted up completely in the auto garage. Have you ever wondered whether the small hydraulic jack and the bigger one are cousins? Yes, they have the same lineage. Their forefather was Blaise Pascal and Joseph Bramah.


Blaise Pascal was the man who invented the Pascal’s principle, and Joseph Bramah was the man who made the first hydraulic press. Hydraulic press, hydraulic jack , and the car lifter in garage work on the same principle.

Working Principle of Hydraulic Jack

The working principle of hydraulic jack is “In a hydraulic system the oil pressure is the same irrespective of the size of the cylinder”. The second principle is the force is the multiplication of hydraulic pressure and area of cylinder. The smaller cylinder and the bigger cylinder are the two parts of the working hydraulic parts.

The smaller cylinder is the one where you pump oil by operating the handle and the second cylinder is the one that you put below the car you want to lift. The second cylinder being bigger in diameter can lift the car since the as the force supplied by the cylinder is equal to the area.

If the diameter of the cylinder is two times in diameter compared to the smaller cylinder then the area will be four times bigger. If the of cylinder ratios is three then area is 9 times bigger and is the ratio is 4 then the area is 16 times bigger. Now since the force is area into the pressure and the pressure in smaller and bigger cylinder is the same force gets multiplied by the ratio of square of the diameter

In the stroke if you apply the force of 1 kilogram, it gets multiplied by the square of the ratio of diameters. So the force of 1 Kg gets increased by 4 or 9 or 16 times depending on the ratio being 2, 3 or 4 times. So with one hand you can lift the 10 toner truck fully loaded if the ratio of diameter is 100 times.

Of course the lift will be smaller. You will be able to pump oil and the amount of oil pumped will decide how much the car will lifted. The volume being pumped depends on stroke of pump and the diameter of the cylinder. You do not require the car to be lifted completely out of ground, it should be just enough to get it off the ground. So a small clearance will do.

However if you wish to lift the car completely as they do in an auto garage, you can do it by hand but the amount of oil that you will require pumping will be huge and you may require a complete day if you wish to do it manually. It is possible if you have that much time with you.

If you do not have the time, you have your friend “electricity”. The electrical pumping can do it is minutes, what will take you the entire day.

So now you know how the hydraulic pump works.