Periodically, they test, adjust, clean, and tune engines to keep them in proper working order. The level of service is determined by the difficulty of the problem. In large shops, mechanics usually specialize in certain types of work, such as diesel engine overhaul, hydraulic maintenance, or clutch and transmission repair. Others specialize in certain repairs, such as air-conditioning units often included to cool the cabs of combines and large tractors, or the repair of specific types of equipment such as hay balers. In addition, some mechanics assemble new machinery, do body work, and repair dented or torn sheet metal on tractors or other machinery.
Mechanics use many basic handtools, including wrenches, pliers, hammers, and screwdrivers.
They also use precision equipment, such as micrometers and torque wrenches, in addition to welding equipment and power tools to repair broken parts. Increasingly, computerized engine testing equipment, such as dynamometers, engine analysis units, and compression testers, is used to measure engine performance and to find worn piston rings or leaking cylinder valves. Soon, mechanics will have access to computerized diagnostic equipment to monitor and locate malfunctions without turning a wrench. New technology allows farmers to achieve record crop yields from small plots of land by more precisely tailoring their tillage to accommodate the soil conditions of each. These computerized systems link farmers to satellites and other advanced devices to better monitor their crops and land use.