61.—Wheel and axle comined with a screw.details

A wheel and axle may be combined with a screw, as shewn in the contrivance of fig. 61. When the handle is turned, the screw-thread on its axle sends the cog-wheel forward one tooth for every revolution. Such a screw, which itself does not advance in a nute, but which merely rotates in ordinary bearings, is called an ‘endless’ screw. (pp. 139, 140)