Heavy vehicle mechanics carryout routine servicing and repair on commercial vehicles such as trucks/trailers, vans, jeeps, buses and coaches. Many work for road haulage companies. Usually the work is based around servicing, diagnostics and repairs. The aim is to ensure that vehicles are kept on the road as long as possible. As well as routine servicing, major overhauls are undertaken at regular intervals. Faults are diagnosed and the defective components are repaired or replaced as necessary.