combine harvester
A farm machine that harvests, threshes, and winnows ripe grain.
combine harvester: grain harvest, threshing, and cleaning in one pass
A combine harvester is a single machine that cuts standing grain, separates the seed heads from the stalks, and removes chaff and debris, all in one continuous operation across a field. The name combines those three functions: harvesting, threshing, and winnowing. Most modern combines handle wheat, barley, oats, and soybeans, though models vary in capability and capacity.
The machine consists of a cutting head or platform at the front, which may be a conventional cutter bar, a rotary disc system, or a stripper head depending on crop type and regional practice. Behind this is a conveyor that feeds cut material into the threshing mechanism, typically a rotating drum or rotor that beats grain loose from the chaff. A separation system then uses a combination of gravity, air flow, and vibrating sieves to drop clean seed into a hopper while ejecting straw and chaff from the rear.
Capacity and configuration
Combine size is measured primarily by grain tank capacity, ranging from small self-propelled units holding 2,000 to 3,000 liters on smaller farms, up to 10,000 liters or more on large-scale operations. Header width, the cutting width at the front, typically runs from 2.5 to 9 meters. Engine power varies from around 75 kilowatts in compact models to over 300 kilowatts in the largest machines. Tracked and wheeled versions both exist, with tracks preferred in wet or soft ground and wheels favored for road transport and drier soils.
Common failure points include wear in the threshing mechanism, blockages in the grain elevator or separation system, and hydrostatic transmission problems in self-propelled machines. Uneven threshing, cracked grain, or excessive chaff in the tank signals adjustment is needed. Maintenance between seasons focuses on cleaning residue from internal passages, replacing worn rotor bars or concave elements, and inspecting belt and chain drives.
Combines sit at the top end of agricultural equipment cost, often exceeding 300,000 euros for new machines with current technology. Custom hire and contractor services are common in regions where farm size does not justify ownership. Operator skill significantly affects both output quality and wear rate, making training and experience valuable across cereal-growing regions worldwide.