Transmission systems are crucial components of many machines and mechanisms. Ken Hurst (1998) highlights that whether you are designing power plants, cars, or washing machines, the power transmission system is an integral component responsible for product success or failure. The components that comprise a power transmission system include those that transfer power directly (coupling and shaft), speed and torque multiplication components (gears, belt drives, etc.), and the related mechanisms (clutches, brakes, etc.; see Freeman & Velinsky, 1995). Transmission system design is a multistage iterative process of sequential generation and modification of design decisions. These decisions define in many respects the technical and economic characteristics of future products. Searching for suitable design decisions is a highly complex and time-consuming problem due to the necessity to consider and analyze many heterogeneous functional, technical, and economic factors. However, extensive computations, including solving very complex optimization tasks, are needed. As a rule, the design procedures are provided only by a very competent and experienced designer. With ever more complex and combinatorial decisions to be made, even the best designer will need competent design support, of which there is little. Therefore, the design of transmission systems is a wide open area for development and application of decision-making and decision support technologies.