jack-screw

The Sailor's Word-Book

A small machine used to cant or lift weighty substances, and in stowing cotton or other elastic goods. It consists of a wooden frame containing cogged iron wheels of increasing powers. The outer one, which moves the rest, is put in motion by a winch on the outside, and is called either single or double, according to its increasing force. The pinions act upon an iron bar called the spear.

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