The working principle of pulley
Since the pulley is a simple machine, it helps reverse the direction of the lifting force. When one end of the rope is pulled down, the load on the other end of the rope is pulled up. So the direction of the force changes from down to up. Pulleys can work on one, two, or four wheels.
The theory of operation of the pulley system assumes that the pulleys and lines are weightless and that there is no energy loss due to friction. The more pulleys, the easier it is to pull or lift an object. It is still easier to lift the object if the more pulleys involved and the greater the distance pulled.
Two kinds of pulley
Fixed pulley:
When the pulley is hinged to a fixed bracket, it is a fixed pulley. That doesn't mean it can't move. It changes the direction of the force on the rope or belt moving along its circumference. It can rotate freely around a fixed pivot.
Moving pulley:
A pulley that moves freely up and down with the load is called a moving pulley. It can rotate like a fixed pulley and is supported by two parts of the same rope, giving it two mechanical advantages.
Therefore, we can say that a single fixed pulley can only be used to change the direction of the applied force, while a moving pulley can be used to reduce the required input force.
