The hydraulic jack is a device used for lifting heavy loads by the application of much smaller force. It is based on Pascal’s law, which states that intensity of pressure is transmitted equally in all directions through a mass of fluid at rest.


WORKING PRINCIPLE: The working principle of a hydraulic jack may be explained with the help of Fig. 23. Consider a ram and plunger, operating in two cylinders of different diameters, which are interconnected at the bottom, through a chamber, which is filled with some liquid.

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Fig. Hydraulic jack Fig. Plunger


W= Weight to be lifted,

F = Force applied on the plunger,

A = Area of ram, and

a = Area of plunger.

Pressure intensity produced by the force F, p = F/Area of plunger = F/a

As per Pascal’s law, the above intensity p will be equally transmitted in all directions.

Therefore, The pressure intensity on ram = p = F/a = W/A or W= F(A/a)

Above Equation indicates that by applying a small force F on the plunger, a large force W may be developed by the ram.

Mechanical advantage of press = A/a

If the force in the plunger is applied by a lever which has a mechanical advantage (L/l) then total mechanical advantage of machine = (L/l)(A/a)

The ratio (L/l) is known as leverage of press.

Hydraulic jack may be employed for the following jobs:

  • Metal press work (to press sheet metal to any required shape).
  • Drawing and pushing rods.
  • Bending and straightening any metal piece .
  • Packing press.

31 Responses to “Working Principle of HYDRAULIC JACK or HYDRAULIC PRESS”

  1. Somshankar

    difficult to understand


    What should be the properties of fluids used in hydraulic hack?

  3. yasir

    eng inf abt thermodynamics


    You help me to assigment of hydraulic thanks i am student of IERT ALLAHABAD RAHUL MAURYA 78********

  5. admin

    Thanks, please dont give the phone no. on any public forum

  6. Kathelin liana

    Yeah its good and it helped in in my physics project. I am in class VIII and it helped me very much.
    THanks a lot.

  7. Kathelin liana

    But only give a bit easier diagram with properly labelled

  8. Lawyers

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  9. mukesh verma


  10. rishi khalate

    it makes our way very easy to resolve or perform any cumbersome activity.

  11. admin

    Thanks for the appreciation.

  12. Mayesh

    It really helped for understanding science…and also builds our today”s science

  13. Indrajeet kumar verma

    its help me preparation of sem exam . IERT Allahabad

  14. A passer by

    Makes it incredibly easy to understand and apply the mechanisms and principles. I didn’t even realise you could apply the mechanism of pivot and lever to multiply the mechanical advantage. Thankyou.

    One improvement: seperate out and number the diagrams so it’s immediately obvious what goes where (and second diagram is a bit…squashed).

  15. admin

    Thanks a lot.

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  17. Piyush katiyar

    giving great ideas for studying science

  18. Bhavika singh

    Helped a lot in my project. Thanks☺

  19. admin

    Our Pleasure. Thanks for the comment.

  20. Shubha maurya


  21. admin


  22. Sheehan Ghosh

    Excelent content allocation.Well planned work Hard work appreciated.


    Thank you very much

  24. William

    I like your site. I have a project am building using principle of hydraulic press system where effort and load move at high speed back and forth. I need your help. My questions are as follows:
    1. How and what type of valves to I use if I need the fluid in the load and effort cylinders remain constantly full without emptying back to tank considering plunger and load move back and forth fast?
    2. How to the valves refill the plunger when need be?
    3. To improve load with relative small effort, how can I incorporate electric powering system?

  25. sebalisa steven

    thanks engineer

  26. Ezeora, Boniface Ugochukwu

    Needs Introduction to Hydraulics Technology.

  27. Peter ndlovu

    Its awesome

  28. admin

    Our Pleasure

  29. Jigs

    Can you please forward me more write up on that. I have to make a project on that

  30. anu

    well explained the principle, will be more useful for the mechanic students like us .

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