After Christmas. Weather doesn't look to go outside, so we're playing christmas gifts. Under the Christmas tree Lego Technic rules this year. First, we made truck 8065 that we can load and unload the cargo by the knob located on the cab. While we were building the truck we understood how the worm gear works. By that gears we can get large gear reductions. To remove the cargo (3/8 rotation), we must 3 full turns the knob. Worm gear is self-locking. It means that the system can be driven from one side only. Worm can drive the gear but gear cannot drive the worm.