Liver is a machine consisting of a beam or rigid rod pivoted at a fixed hinge or a fulcrum.Livers are classified by the relative position of the fulcrum and the input output forces. We commonly called as input force as effect and out force is the load or resistance. It may three classes of levers by the relative location of the fulcrum and the effort.


CLASS 1 :


The fulcrum in the middle: The effort is applied on one of the fulcrum and the resistance on the other side,  

Eg: Crow Bar, And a pair of scissors.

CLASS 2 :


Resistance in the middle: The effort is applied on one side of the resistance and the fulcrum is located on the other side.  

Eg: a Wheel barrow, Nut Cracker, Bottle Opener, break Pedal.

CLASS 3:


Effort in the middle: The resistance is on one side of the effort and the fulcrum is located on the other side. 

Eg: a Pair of Tweezers, Human mandible etc.