Lifting loads

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.