differential windlass

American  

noun

1. a pair of hoisting drums of different diameter turning at the same rate, such that a pulley suspended below them on a line wound on the larger drum and unwound from the smaller drum is raised with mechanical advantage.

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differential windlass British  

noun

1. Also called: Chinese windlass.  a windlass employing the velocity ratio incurred in unwinding from a small drum while winding onto a larger drum rotating at a common speed

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