How a hydraulic jack works

A hydraulic jack is a small device which  can lift heavy loads with very little  effort by the jack operator it works on  the lever principle if we place a liver  under a heavy object we can lift it by  racing the free end of the lever.
 The  distance the object is lifted can be a  few inches but the free end of the liver  has to travel much more distance than  that and that is a ratio of  multiplication of the force if we move a  lever  times the distance it will lift  the object.
We can lift  pounds with  an effort equivalent to  pounds thus  we will have to move the lever  inches  for every inch of lifting one drawback  is that the free end of the liver is  limited as to the distance it can travel  so the object cannot be lifted very far  from the ground.
 The way to solve that  problem is by using a mechanism which  allows swinging of the free end of the  liver without the object going down  again if we can swing the lever several  times we can lift the object for a  practical distance