Mechanical watches use little springs to provide the kinetic energy necessary to get all those cogs and sprockets working well enough to turn the handles at the required speed. The principle needn't be restricted to timepieces though.
In truth, the tradition of spring-loaded cars and other kinds of toys is an old one. Just pick it up, turn the key in the back and let it rip.
In recent times, this type of toy seems to have taken a backseat to electrical devices, but 3D printing technology may facilitate a return to the roots, so to speak.
The 3D printed spring-loaded car
The idea behind the toy is an old and simple one, but the application is all new, the result of plastic-based 3D printing technology.
Greg Zumwalt (also known as sgzumwalt) is a Thingiverse user that uploaded a PLA Spring Motor Rolling Chasis design back in 2014.
Based on that design, a man by the name of Jason King designed and built the car you see in the attached gallery, oversized spring and all.
The main body of the car is made from colorFabb’s Dutch Orange filament. That includes the wheels and the large gears.
The spring, however, is made from RoboSavvy’s Green filament, while the two stationary components (two sides of the chassis) were made from colorFabb Blue.
Most of the parts were made from PLA plastic with 10% infill at a layer thickness of 200 microns, except the spring and knob which had 100% infill due to the higher strength required.
This means that the car will degrade in nature easily enough, instead of adding to the plastic pollution, the mountains that kill the real mountains.
Environmental drama aside, King did have to go through a couple of prototypes before he settled on a final design. There was a flaw with the 3D printer, whose acrylic build plate had to be swapped for a glass model.
He also had to modify the wheels of the car, using ninjaFlex rubber to give them some better traction, allowing them to still be fully 3D printed but still get the same benefits as though they'd been wrapped in a rubber band.
This isn't a commercial product, but with some care you should be able to find a model on Thingiverse and modify it to your heart's own content.