Engino Discovering STEM: Mechanics - Gears and Worm Drives (12 models) 9yrs+Learn how gears can easily reduce or increase speed, change force or transfer motion from one position to another. Discover how worm drives are used to greatly reduce rotational speed and how screws can convert rotational motion to linear, while greatly increasing force. Build 12 working models such as an experimental crane, a gearbox, a carousel, a helicopter, a screw press and a crane with a rotating arm. You can find easy to follow building