Jackscrews

Part of speech: noun

Definitions

1. A mechanical device composed of a threaded shaft that is used for lifting or positioning heavy objects by turning a handle or screw mechanism
2. An apparatus featuring a screw mechanism that raises, lowers, or adjusts the height of heavy loads through rotational motion
3. A type of lifting equipment with a screw drive that allows for fine adjustments in height and stability of heavy items during assembly or maintenance

Etymology: "Jackscrews" is the plural of "jackscrew," a compound formed from "jack" and "screw." The screw element is the familiar threaded fastener, rotated to drive a load up or down by small increments. The "jack" element is the older and more interesting part: it was a common nickname and generic name for a labour-saving device, applied to lifting tools such as the mechanical jack, which raises heavy loads with a lever or screw. Combining the two produced a term for a screw mechanism used as a lifting device, so the compound describes its function directly rather than naming a specific inventor or brand. Its meaning therefore stays close to its parts: a screw that does the work of a jack.