uni directional gearbox

This is an experimental demonstration for a small idea.
Date of creation : Aug 23, 2009
special feature : the output shaft rotates in only one direction regardless of the input rotation

Since I saw the worm gear first, I have been wondering why the worm gear has loose axlehole unlike most gears. And during Aug of 2009, I came to this idea to utilize the loose axlehole.
The gear combination consists of a worm gear and two 16 teeth gears.


The video of internal motion explains everything, I hope.
When the input rotation reverses its direction, the worm gear scrawls along the axle
and connect to the other 16 teeth gear. A short delay of the output shaft comes from this crawl.
From the viewpoint of worm gear, crawling requires less torque than driving the wheels.
So, it crawls as far as it can, and then move the 16 teeth gear.