A block and tackle[1][2] or only tackle [3] is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads.
The pulleys are assembled to form blocks and then blocks are paired so that one is fixed and one moves with the load. The rope is threaded through the pulleys to provide mechanical advantage that amplifies the force applied to the rope.[4]
Hero of Alexandria described cranes formed from assemblies of pulleys in the first century. Illustrated versions of Hero's Mechanica (a book on raising heavy weights) show early block and tackle systems.[5]
- ^ "Tackle" can be /ˈteɪkəl/ in this usage.
- ^ [dead link] "Royal Canadian Sea Cadets - Master Lesson Plan - Level T\\\2" (PDF). Archived from the original (PDF) on 2013-03-09. Retrieved 2009-12-27.
- ^ Manual of military engineering
- ^ Ned Pelger, ConstructionKnowledge.net
- ^ A. P. Usher, A History of Mechanical Inventions, Harvard University Press, 1929 (Dover Publications, revised edition, 2011, ISBN 978-0486255934)