Pulley systems

A pulley is a wheel with a groove on its outer edge and it can rotate freely on an axle or pin fixed on a frame. A load is tied at one end of a smooth rope which passes over the groove. The other end of the rope is used to lower or lift the load. There are two types of pulleys, namely, fixed and movable pulleys.

Fixed pulley

In this pulley, the wheel remains at one location when a load is lowered or raised by the rope as illustrated in Figure

Fixed pulley — Raising a load using a fixed pulley

Movable pulley

This type of pulley moves when the load is being raised or lowered as shown in Figure. The combined use of fixed and movable pulleys reduces the effort for lowering or raising the load.

Movable pulley — Raising a load using a combination of fixed and movable pulleys

Uses of pulleys

Pulleys are used to raise or lower loads. For example, to raise and lower flags. Another example is the raising of bricks and concrete to the upper levels during construction.