This report documents the program conducted to demonstrate the application of a flywheel-powered propulsion system to underground mining shuttle cars. Such application can replace the present electrical trailing cable common to most shuttle cars and thereby eliminate those safety hazards, maintenance problems, and haulage route limitations inherent in the trailing cable. Described are the activities undertaken to specify and design a flywheel of optimum size, shape, and material; to identify the best concepts of input and output systems; and to achieve installation of the power package into a shuttle car. The resultant flywheel-powered shuttle car is an FMC Corp. Model 6l Shuttle Car, 6-ton capacity, 20-ton gross vehicle weight, powered by a flywheel system with 4.5-Kilowatt-hour usable energy. The completed vehicle was delivered to the Bureau of Mines in Bruceton, Pennsylvania, for testing and evaluation.