A link between machine functionality, operations, performance and decision making in the management of power sources and field operations were presented in this book. Depreciation and functional deviation of a machine from its original state at manufacture could put the life of a machine in danger of breakdown or obsolescence, which is counted a loss to any such organization or the entrepreneur. To avoid such losses, an understanding of machine systems functionality and a well organized maintenance programme designed to maintain, prevent or restore machine to near original state is required. Vocational training and entrepreneurship education in Nigeria's tertiary institutions has made possible a do-it-yourself skill acquisition in machine fault tracking, maintenance and repairs. A bimodal training programme packaged and presented in this book is all that is required for managerial decision making, maintenance and qualitative service delivery.