bd40bc7c7a Belt and pulley systems. This allows even simple wheels with wooden axles running in wooden blocks to still turn freely, because their friction is overwhelmed by the rotational force of the wheel multiplied by the mechanical advantage. A pulley may also be called a sheave or drum and may have a groove or grooves between two flanges around its circumference. ISBN0-486-25593-X. Fixed pulley Diagram 1: The load F on the moving pulley is balanced by the tension in two parts of the rope supporting the pulley. p.180.
Rope and pulley systems. Handbook of Rigging: For Construction and Industrial Operations. By adding a pulley to the fixed block of a gun tackle the direction of the pulling force is reversed though the mechanical advantage remains the same, Diagram 3a. Here are examples where the fixed point is not obvious:. .. In this case, a force balance on a free body that includes the load, W, and n supporting sections of a rope with tension T, yields:. A History of Mechanical Inventions. This allows for mechanical power, torque, and speed to be transmitted across axles. Pulley in oil derrick . A single movable pulley is supported by two parts of the same rope and has a mechanical advantage of two.