Basic Information

A major challenge in building a tree house is lifting the loads to the desired height. The pulley system is a tried and true method used here. In a pulley system the forces are combined and distributed via pulleys. This reduces the force required to lift the load. Pulley systems can reduce the required force in different ratios. However, the rope length to be pulled always increases in the same ratio.

Variable Pulley Systems

Further Information

Explanation of the Pulley System

In the example shown in figure 1, the fixed pulleys are at the top and the loose rollers are at the bottom. At the left is a pulley system where the loose pulley hangs on two ropes upon which the load is evenly distributed. This means that half of the load is on each of the two ropes. One end is fixed at the top while the other end is deflected and pulled. It has to be pulled with only half the force to lift the load. 

In the middle pulley system the loose pulley hangs on three ropes upon which the load is distributed. Only one end is deflected and then pulled. Then you only have to pull with one third of the force. 

With the right pulley system the load on the loose pulley is distributed over four ropes and therefore only a quarter of the force has to be applied.

Reducing the force with which you have to pull also has a price. By spreading the load over several ropes, all these ropes must also be hauled in to lift the load. This increases the length of the rope to be hauled in the same proportion as the force is reduced.


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Institut für Erlebnispädagogik
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Funded by Erasmus+ "Youth in Action"

The website and the content was developed in the project "Treehouse Camps - a Method to Strengthen Key Competences and Integration in Youth Work".

Project duration: September 2018 - August 2021