Inspect brake systems, steering mechanisms, wheel bearings, and other important parts to ensure that they are in proper operating condition. Use handtools such as screwdrivers, pliers, wrenches, pressure gauges, and precision instruments, as well as power tools such as pneumatic wrenches, lathes, welding equipment, and jacks and hoists. Adjust and reline brakes, align wheels, tighten bolts and screws, and reassemble equipment. Examine and adjust protective guards, loose bolts, and specified safety devices. Perform routine maintenance such as changing oil, checking batteries, and lubricating equipment and machinery. Test drive trucks and buses to diagnose malfunctions or to ensure that they are working properly. Raise trucks, buses, and heavy parts or equipment using hydraulic jacks or hoists. Attach test instruments to equipment, and read dials and gauges to diagnose malfunctions. Rebuild gas or diesel engines. Inspect and verify dimensions and clearances of parts to ensure conformance to factory specifications. Inspect, test, and listen to defective equipment to diagnose malfunctions, using test instruments such as handheld computers, motor analyzers, chassis charts, and pressure gauges.