In winter quarter 2020, I took an intermediate design course where the quarter-long project was to work as a team to develop an electric tricycle drivetrain. The system requirements are shown in the table below. Click here for to view our PowerPoint which outlines the entire design process and detailed analysis. 

For our project, we were given a list of requirements as shown in the table below:

As with all design processes, we began with brainstorming sessions to generate ideas, as shown in the photo grid below. We first needed to design a general layout of the tricycle for the drivetrain to operate on. Each design was then compared using a pairwise comparison matrix using the criteria of weight, safety, maneuverability, economical, aesthetics, and rider comfort. 

Vehicle was the most effective design against the criteria. Next we did a similar brainstorming session for drivetrain designs, including belt operated, shaft operated, and chain operated designs and we determined that a simple chain and sprocket was our best solution to the problem. We made a quick CAD model of this design to show the overall layout of our prospective design. 

We modified our design to account for lateral and downhill tipping conditions, dropping down the center of gravity and adding a differential and implementing an indirect steering mechanism. The new layout looks like this:

Once the overall layout was confirmed, we conducted in depth analyses to size components and select materials. This includes weight distribution, efficiency ratings, power output, time to speed calculations, top speed calculation, and total range that the tricycle will cover. This helped us determine the shaft materials and diameters, bearing sizes and types, sprocket sizes and teeth, and the chains. The final design is shown below: