A combine harvester is one of the most transformative machines in modern grain farming. It combines reaping, threshing, and winnowing into a single operation — saving labor, time, and costs. This guide explains the main parts of a combine, how they work together, and practical maintenance tips to keep your machine running at peak efficiency.
What Is a Combine Harvester?
A combine harvester is a self-propelled machine used to harvest cereal crops such as wheat, rice, barley, maize (corn), and soybeans. The name “combine” comes from combining three operations: reaping (cutting the crop), threshing (separating grain from stalk), and winnowing (cleaning the grain).
Main Parts of a Combine Harvester
| Part | Description | Function |
|---|---|---|
| Header | Front module that gathers standing crop | Cuts and feeds crop into the machine |
| Reel | Rotating guide on the header | Guides crop into the cutter bar |
| Cutter Bar (Knife) | Series of reciprocating blades at the header | Cuts crop close to ground |
| Feeder House | Conveyor between header & threshing | Moves cut crop into the threshing drum |
| Threshing Drum / Cylinder | Rotating cylinder with rasp bars | Separates grain from stalk and heads |
| Concave | Curved grate below the drum | Allows grain to fall while retaining straw |
| Straw Walkers | Long oscillating trays | Shake out remaining grain from straw |
| Cleaning Sieves & Fan | Adjustable sieves & suction fan | Remove chaff and light debris from grain |
| Grain Tank / Hopper | Internal storage bin | Collects cleaned grain before unloading |
| Unloading Auger | Hydraulic auger/pipeline | Transfers grain to trailer/truck |
| Engine & Transmission | Powerplant and driveline | Drives wheels, header, drum, and auxiliaries |
How a Combine Works — Step by Step
- Cutting (Reaping): The header's cutter bar cuts the standing crop.
- Feeding: The reel and feeder house move the cut crop into the threshing drum.
- Threshing: The rotating drum beats the crop, separating grain from straw and heads.
- Separation: Concaves, straw walkers, and separators release loose grain from straw.
- Cleaning: The fan and sieves remove chaff, light material, and dust from grain.
- Collection: Clean grain is stored in the grain tank; straw is ejected at the rear.
- Unloading: Grain is transferred using the unloading auger to transport vehicles.
Maintenance Tips — Daily & Seasonal
Daily (During Harvest)
- Check engine oil, coolant, and hydraulic fluids before starting each day.
- Clean air filters, radiator fins, and cooling systems to prevent overheating.
- Inspect cutter bar, knives, and guards — replace or tighten damaged parts.
- Remove straw and dust buildup around the engine, belts, and bearings.
- Check tension on belts and condition of chains & pulleys.
Seasonal / Post-Harvest
- Replace worn rasp bars, concaves, sieve sections, and knife sections as needed.
- Drain and change engine oil and hydraulic fluids per manufacturer schedule.
- Clean fuel system and filters; treat fuel if storing the machine long-term.
- Grease bearings, universal joints, and pivot points thoroughly.
- Store in a dry, covered area; apply anti-corrosion spray on exposed metals.
Safety Precautions
- Always stop the engine and disengage moving parts before inspecting or clearing blockages.
- Keep all protective guards and shields in place; never operate with removed guards.
- Be cautious around the header and unloading auger — they move quickly and can cause serious injury.
- Carry a fire extinguisher on the machine and ensure a trained operator is present during harvest.
Common Causes of Grain Loss & How to Fix Them
- Wrong drum clearance / concave setting: Adjust per crop guide to reduce broken grain or unthreshed heads.
- Incorrect sieve or fan speed: Fine-tune to balance cleaning and grain loss.
- Worn threshing parts: Replace rasp bars and concaves to maintain separation efficiency.
- Overloading the header or tank: Reduce forward speed or increase unloading frequency.
Brands & Models
Popular combine manufacturers include John Deere, New Holland, Claas, Kubota, Mahindra, and Yanmar. Choose a model sized to your farm’s acreage, crop type, and available service network.
Frequently Asked Questions (FAQ)
Q1. What crops can a combine harvest?
Wheat, rice, barley, oats, maize (corn), soybeans, pulses, and many small grains — with appropriate header and settings.
Q2. How often should I service the combine?
Follow the manufacturer’s manual — typically every 100 operating hours for routine checks; perform a full service after harvest.
Q3. Why is cleaning the combine daily important?
Dust and crop residue can cause overheating, belt/chain wear, and even fire risks — daily cleaning prevents these issues.
Q4. How can I reduce grain loss?
Monitor the grain loss indicator, adjust concave/drum clearance, optimize sieve & fan settings, and ensure threshing parts are in good condition.
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