A professional who repairs, tests, and installs mechanical units, such as fuel and water pumps, control valves, governors, distributors, windshield wiper motors, and door engines on streetcars, trackless trolleys, and buses. Respnsibilities include:

• Disconnects and removes unit from vehicle, using handtools.
• Disassembles unit and cleans parts with chemical solution.
• Inspects parts for wear or damage.
• Removes foreign particles from unit, using compressed air blower.
• Repairs, replaces, or adjusts components, such as needles, springs, bolts, relays, and airhoses.
• Tests air-control valve, air pipes, and airhoses for air leaks.
• Tests magnetic, hydraulic, and pneumatic control valves that are used to open and close doors and inspects radiator shutters, and other mechanical units on vehicle.
• Reassembles and installs unit in vehicle.
• May be designated according to type of mechanical unit repaired as door-engine repairer; windshield-wiper repairer.