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.

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

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