* Screw: The spiral design of the handle is essentially a screw. It converts rotational motion into linear motion, allowing you to easily pull the suitcase along.
* Wedge: The shape of the suitcase's wheels also acts as a wedge. The angled surface helps to reduce friction, allowing the suitcase to roll smoothly.
So, while a spiral suitcase itself isn't a single simple machine, it cleverly utilizes the principles of both screws and wedges to make moving luggage easier.
