Image: Spiral-screwdriver

Description: push drill, one of the very few mechanisms that use a screw in the "backwards" sense, to convert linear motion to rotational motion. It has helical screw threads with a very large pitch along the central shaft. When the handle is pushed down, the shaft slides into pawls in the tubular stem, turning the bit. Most screws are "self locking" and axial force on the shaft will not turn the screw.
Title: Spiral-screwdriver
Credit: Own work (Original text: Photograph by Bill Bradley. billbeee 21:25, 19 May 2007 (UTC)) Feel free to use it, just credit me as the photographer. You can contact me through my website my website
Author: Billbeee at English Wikipedia
Usage Terms: Creative Commons Attribution 2.5
License: CC BY 2.5
License Link: http://creativecommons.org/licenses/by/2.5
Attribution Required?: Yes