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What is a lever?

A lever is a rigid bar that pivots about a fulcrum. It transmits an input motion and force, (the effort) through the lever pivoting on a fulcrum to a resistance force called a load.


The load is anything that is being moved by a lever.

Effort force

The effort force is the energy applied to a lever to move a load.


The fulcrum is the point at which the lever pivots. A lever may rest on a fulcrum or it may swivel on an axle, e.g. a see-saw (class 1 lever) and a wheel barrow (class 2 lever).

Classes of lever

There are three classes of levers. Each class of lever has the load and effort force in specific positions relative to the fulcrum.

Classes of lever

Class 1 lever

A Class 1 lever has the fulcrum between the load and the effort force.

Class 2 lever

A Class 2 lever has the load between the fulcrum and the effort force.

Class 3 lever

A Class 3 has the effort force between the load and the fulcrum.

Bell Crank Lever

A bell crank lever is an angled Class 1 lever. It is a Class 1 lever because the fulcrum is between the load and the effort force.

The bell crank lever is used when the effort force must be at an angle, usually a right angle, to the load.

Bell crank lever


A cantilever is a beam that is fixed at one end only. Load is applied to the unsupported end.

A cantilever may be classified as a type of Class 1 lever as fulcrum is between the effort force and the load.


Mechanical advantage (MA)

Machines and mechanical devices are used to create a mechanical advantage. Mechanical advantage helps us do work such as move heavy loads for a relatively small amount of effort.

Mechanical advantage may be worked out by dividing the load force by the effort force,

Mechanical advantage

Creating a mechanical advantage using a lever

Levers create a mechanical advantage.  The long lever pivoted near one end enables a small effort force to lift a heavy load.

Lever mechanical advantage

This type of mechanical advantage is called distance mechanical advantage.

The mechanical advantage of a lever is worked out by dividing the distance of the effort force to the fulcrum by the distance of the load force to the fulcrum.

Mechanical advantage, distance

Click here to view a PDF version of this resource. Levers PDF Levers PDF
Copyright Laszlo Lipot.