Several highly technical skills are required to design and develop a self-propelled vehicle. One such skill is to design or select the appropriate size drive train. The more accurately this can be accomplished, the more significant will be the savings in development cost. Various references are available on the theoretical approach; however, a significant unknown is the relationship to practical applications. Zahnradfabrik Friedrichshafen AG has over many years of experience developed a computer program that can reliably assess the service life of power train designs. The reliability of this approach has been proven by both vehicle manufacturers and end users.