In the diagram shown here, the number of rope sections of the tackles shown is as follows: They are common on boats and sailing ships, where tasks are often performed manually, as well as on cranes and drilling rigs, where once rove, the tasks are performed by heavy equipment. A block and tackle system amplifies the tension force in the rope to lift heavy loads. The process of threading ropes or cables through blocks is called ' reeving', and a threaded block and tackle is said to have been 'rove'. An assembly of blocks with a rope threaded through the pulleys is called tackle. All these are 'rove to disadvantage' (see below).Ī block is a set of pulleys or sheaves mounted on a single frame. Overview Various ways of rigging a tackle. Illustrated versions of Hero's Mechanica (a book on raising heavy weights) show early block and tackle systems. Hero of Alexandria described cranes formed from assemblies of pulleys in the first century.

The rope is threaded through the pulleys to provide mechanical advantage that amplifies the force applied to the rope. The pulleys are assembled to form blocks and then blocks are paired so that one is fixed and one moves with the load. System of two or more pulleys and a rope or cableĪ block and tackle or only tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads.

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