A pulley is a simple machine which reduces effort applied for a mechanical work. The pulley is composed of a circular plate joint to an axle with a shaft. The circular disc has a groove to hold rope in it for the movement. The pulley is used widely in mechanical equipments. The pulleys are multitasking and have many usages in mechanical applications. The invention of pulley is a great help to mankind to reduce power input in many things. The pulleys are of many types and sizes depend upon their usage and where required. The question is how to make a pulley with the appropriate accessories available. Making a pulley is a simple and convenient process. One must have a circular disc with a groove to hold a rope or string and a shaft to attach an axle. This process leads to making a simple pulley to lift heavy loads. Pulleys are used to lift heavy loads conveniently without putting much effort. Machines like cranes and hydraulic jacks are fitted with pulleys in their mechanism to lift heavy loads. There are main three types of pulley systems rope pulley system, belt pulley system and pulley to pulley system. 

The rope and pulley system is a best example to simple machine. In this system a single rope runs through the groove of the pulley and the pulley is attached to a particular place, the circular motion reduces the friction which reduces the effort. In ancient times people use to draw water from the well with the help of rope pulley system. In those times only few people know how to make a pulley and its proper usage. In today's times the usage of pulley system has increased. The belt pulley system is used in heavy machinery like motors, cranes, robotic engines etc. This reduces the friction in circular movements and enhances the acceleration of the motor.

The pulley to pulley system is subcategorized in three different arrangements of pulleys. First system is known as fixed pulley arrangement, in this system the pulley has a fixed non moving axle anchored at a place. The load is equal on both the sides and used to change mechanical direction. The problem aroused when mechanical experts wondered how to make a pulley on moving system. The second type is movable pulley system and axle is free in this type which is used to multiply force. Third one is compound which combination of fixed and movable pulleys.