FLYWHEEL and SPRING ……. pulse motor
This is a curious motor that uses a flywheel, a spring, and a driving circuit to operate. The initial energy comes from a 3v battery pack. A 10 Farad super capacitor supplies the energy to the reed switch driver when the battery is disconnected. It will run for a few minutes on the capacitor alone and is an interesting machine to observe.
Here is my favorite video on this subject. They build a big one, put it in a car, and drive around with it. Wait for the end of the video to find out how they did it . Listen carefully. https://www.youtube.com/watch?v=McDagDBzbHw