Pulley

Definition

The term pulley or pulley system is used for any of a number of related simple machines, having the following features:

• A rotatable wheel.
• A rope or belt or string passing over and around the wheel, and curving over it, so that linear motion of the rope corresponds to rotation of the wheel.

A pulley is a simple machine that works by changing the direction -- the direction in which the rope hangs at one end can differ from the direction in which the rope hangs at the other end, allowing the application of a force in one direction to move a load in another direction.

Here are some examples of pulley systems in action:

Scenario	Picture
fixed pulley with vertical loads	File:Fixedpulleyithverticalloads.png
pulley system on a double inclined plane
pulley system for block piled on block	File:Pulleysystemforblockpiledonblock.png