Design Problem

In Kenya, Mkokoteni carts are vital for transporting goods but face challenges like road blockage, strain on pushers, accidents, and animal cruelty. An innovative solution, a spring-powered design inspired by toy cars, aims to alleviate these issues. Harnessing downhill energy assists uphill movement, reducing strain on pushers and enhancing road safety. While electric models offer advanced features, the focus remains on cost-effective solutions to improve the livelihoods of cart operators.

Design Process

The main premise was to use a similar spring mechanism to a toy pullback car to add to a Mkokoteni cart, with a few modifications by adding a reverse gear to make sure the cart would continually move forward and a gear stick to switch when the spring would be engaged, and when it would release.

With this in mind, designing took a lot of research and hands-on testing. I first needed to understand exactly how the springs and gears work in a motor for pullback cars. Understanding this was crucial, so I learned how they worked through research, but I wanted to have a model of one. So I found a design to 3D print, which I could assemble and study, this was an open design so I could come up with ideas to modify it.

Once I was confident that I knew the mechanism, I could go on to design a gearbox focusing on the reverse mechanism. I had originally turned to 3D modelling, but realized that Legos could be much easier and quicker, and I can make as many modifications to it, whilst continually being able to test it. This Lego model taught me many things, such as finding out what springs to use, where I had originally thought of using flat springs, I found that I can use tension springs as they would be much more compact.

Coming to a final lego design, there were limitations with lego in terms of sliding gears. with this, I made a few sketches of a gear box, that could replicate but overcome the limitations of the Lego model. Once these sketches were made, I used Fusion 360 to model this design, through this.

Link to Process Journal and Final Reflection Video

https://sites.google.com/isk.ac.ke/stem-pathways/home?authuser=0