In making repairs, uses a variety of tools, equipment, and testing devices such as pneumatic wrenches to remove bolts; lathes and grinding machines to rebuild brakes and other parts; welding and flame cutting equipment to repair exhaust systems; ammeters, ohmmeters, and voltmeters to locate electrical system malfunction; motor analyzers, spark plug testers, or compression gauges to locate mechanical problems; wheel balancing equipment to balance wheels; scientific testing equipment to help adjust and locate malfunctions in fuel, ignition, and emission control systems; and common hand tools such as screwdrivers, pliers, and wrenches to work on small parts and get to hard to reach places. Knowledge of the mechanical makeup, operation, and working relationships of a variety of heavy duty systems, assemblies, and parts such as diesel, multifuel, and gasoline engines including supercharged and turbocharged engines, automatic and non-automatic transmissions, and gear reductions systems including those with torque converters, planetary gears, and more than one gear range, and driveline assemblies including differentials, power dividers, and dual speed axles, hydraulic lifting, loading, turning, and positioning systems including their mechanical, hydraulic, and pneumatic controls.