A pulley (also called a sheave or block) is a wheel with a groove between two flanges around its circumference. A rope, cable or belt usually runs inside the groove. Pulleys are used to change the direction of an applied force, transmit rotational motion, or realize a mechanical advantage in either a linear or rotational system of motion. Belt and pulley systems A belt and pulley system is characterized by two or more pulleys in common to a belt. This allows for mechanical power, torque,… (More on Pulley)