Date of Award


Document Type




First Advisor

Dr. Van Dyke

Second Advisor

John Meyer


This senior project consisted of redesigning the drive-train for the hand-powered tricycles used by Dokimoi Ergatai. Our team is comprised of Chad O'Toole, Rebecca Carr, Sean Davis, and Stephanie Stevens. We were advised by Dr. Van Dyke and John Meyer. This senior project is divided into two sub-projects consisting of I) tricycle components and 2) a wear testing machine, referred to as WTM for short. The frame interface, upper assembly, and chain tensioner are the three tricycle components that we focused on because the current designs are problematic. The wear testing machine is a slightly different aspect of the project in that unlike the tricycle components which are meant to be used in a third world country, the WTM is designed to test chain tensioners here in the U.S.A. Our final implemented design of the entire front end assembly is capable of being retrofitted on current frame designs to drastically improve comfort, performance, and increase the mean time between failures of the chain. We focused on the chain misalignment, undue wear and stress on components due to complicated manufacturing processes, lack of understanding of drive train tolerances, and lack of repeatability of the manufacturing process of the frame interface and upper assembly. The final design of our chain tensioning device raises the mean time between failures and also expands the time between major part replacement and structural overhauls on the drive train. In addition to the chain tensioner, we improved upon the frame interface between the drive train and the new frame design that was developed in last year's senior project. Finally, we addressed ergonomic and alignment issues in the drive-train and corrected these problems by developing a new upper assembly. We aimed for easy adjustability of crank placement to increase rider satisfaction.


Approved for Honors in the Department of Engineering, Messiah College, 2006.