For a long time, mankind has heavily depended on animal labour and human-powered work. The advent of industrial machines, and motors in particular, has changed the paradigm: today in developed countries, apart from some exceptions like the Netherlands, the vast majority of people moves with motorized vehicles. This thesis is about project Cerberus, an arm-powered vehicle developed mainly for use in competitions and designed by students from Team Policumbent at Politecnico di Torino. The aim of the thesis is to lay some general basis for the design of three-wheeled human-powered vehicles, including those for everyday use on public roads. In this context, the author, in the role of both project manager and head of the mechanical design department for the prototype, decided to write a most complete document incorporating in it both his own, and his teammates work (to whom the credit is explicitly given).