Pulley Systems

Pulley systems are used to provide us with a mechanical advantage, where the amount of input effort is multiplied to exert greater forces on a load.

They are typically used for hauling and lifting loads but can also be used to apply tension within a system such as in a Tensioned Line or Tyrolean. This page explains the basic principles of pulley systems and how they work, for information on how to use them in hauling see the hauling systems page.

Force is an influence that has both magnitude and direction, it is usually given in the dynamic unit of Newtons (N). For ease of explanation we have used kilograms on this page. Additionally, the examples on this page do not take into account the effects of angular vector forces or the coefficients of friction.

History of Pulley Systems

The is no direct evidence to support the first documented use of pulleys and pulleys systems however, it is believed that primitive pulley systems were first used around 1500 BCE by the people of Mesopotamia to hoist and move water.

Throughout history the use of pulley systems have been recorded in numerous text and drawings including works by people such as Greek mathematician and engineer Archimedes and also Hero of Alexandria. These early pulley systems would probably have played a significant role in the construction industry where large, heavy loads such as stone blocks and timber would have required moving.

1:1 Redirect Pulley Systems
diagram of a basic 1:1 redirect pulley system
This page looks at how redirect pulley systems work
The 2:1 Pulley System
diagram of a basic 2:1 redirect pulley system
This page expalins how a 2:1 pulley system works
The 3:1 Pulley System
diagram of a basic 3:1 redirect pulley system
This page expalins how a 3:1 pulley system works
The 4:1 Pulley System
diagram of a basic 4:1 redirect pulley system
This page expalins how a 4:1 pulley system works
The 5:1 Pulley System
diagram of a basic 5:1 redirect pulley system
This page expalins how a 5:1 pulley system works
The 6:1 Pulley System
diagram of a basic 6:1 redirect pulley system
This page expalins how a 6:1 pulley system works

Disadvantages of Conventional Pulley Systems

This conventional 3:1 pulley system has been assembled to raise a load weighing 90kg which needs to be lifted over a height of 50m.

Due to the way that the system has been created we would need at least 150m just to form the 3:1 mechanical advantage, plus an additional 50m to redirect the rope down towards the user who will apply the effort at ground level so all in all this system will require at least 200m of rope!

It is possible to redesign the pulley system making it more compact and manageable while using less rope. To see how this can be done then have a look at the hauling systems page.

Diagram showing a conventional pulley system with a 3:1 ratio lifting a load over 50 metres