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A gin pole is a supported pole that uses a pulley or block and tackle on its upper end to lift loads. The lower end is braced or set in a shallow hole and positioned so the upper end lies above the object to be lifted. The pole (also known as a mast, boom, or spar) is secured with three or more guy-wires. These are manipulated to move the load laterally,[1] with up and down controlled by the pulley or block. In tower construction, a gin pole can also be “jumped” up the completed sections of a tower to lift the higher sections into place.
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The gin pole is derived from a gyn, and considered a form of derrick, called a standing derrick or pole derrick,[2] distinguished from sheers (or shear legs) by having a single boom rather than a two-legged one.
Gin poles are also used to raise loads above structures too tall to reach with a crane, such as placing an antenna on top of a tower/steeple, and to lift segments of a tower on top of one-another during erection. When used to create a segmented tower, the gin pole can be detached, raised, and re-attached to the just-completed segment in order to lift the next. This process of jumping is repeated until the topmost portion of the tower is completed. They can also hold a person if strong enough. Thus opening stage uses, such as in magic shows.
Gin poles are mounted on trucks as a primitive form of mobile crane, used for lifting and relocating loads, and salvage operations in lieu of a more sophisticated wrecker.
References
- ^ Patton, William Macfarland. A treatise on civil engineering. New York: J. Wiley & sons, 1895. 1214.
- ^ Australia, Emergency Management (2006). General and disaster rescue skills for emergency services personnel (PDF) (5th ed.). Dickson, A.C.T.: Emergency Management Australia. pp. 131–132. ISBN 1921152028. Archived from the original (PDF) on 21 March 2014. Retrieved 5 July 2014.
External links
Media related to Gin poles at Wikimedia Commons- Notes & drawings
- tower contractor's description with diagram
- gin pole regulations in Ca.
- gin pole failure leads to lawsuit april 15, 1948 in philadelphia
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