Design, manufacturing, installation, sales, leasing, repair, and service of rail transit operation and engineering vehicles, electrified railway construction, maintenance, and inspection vehicles, urban tram operation and engineering vehicles, road-rail dual-purpose engineering vehicles, large and medium-sized track maintenance equipment, line inspection equipment, line maintenance machinery, rail transit equipment and parts, complete mechanical equipment and parts; installation of electromechanical equipment; professional construction of construction projects; general contracting of various types of rail transit engineering construction projects; professional contracting of steel structure engineering; design, manufacturing, repair, and related technical services of oil drilling professional equipment and metal structures and components; processing of mechanical parts and equipment repair; import and export of goods and technologies; sales of steel; design, manufacturing, sales, and service of axles and other automotive parts. (Projects subject to licensing shall be operated only after obtaining relevant department approvals.)