Parts of a Combine – Labeled Combine Harvester Diagram

All 19 parts on the diagram

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Outside 8

Header The front of the combine. It gathers and cuts the crop and passes it into the machine.
Reel Turning bats that hold the crop against the cutter bar. They sweep it back onto the header.
Cutter bar The bar along the header's front edge where the crop is cut. A knife slides back and forth in it.
Feeder house The sloping housing behind the header. A conveyor inside it carries the cut crop up to the cylinder.
Cab The operator sits in the cab and drives the combine from there.
Grain tank Holds the clean grain until it is unloaded. It sits on top of the machine.
Unloading auger Carries the grain out of the grain tank. A long tube with an auger inside.
Straw chopper At the back of the machine. It chops the straw that comes off the straw walkers and spreads it on the field.

Inside 11

Header auger A large spiral across the header. It gathers the cut crop and feeds it into the feeder house.
Cylinder The turning drum that threshes the crop. Its bars rub the grain out of the heads against the concave.
Concave A curved metal grate that wraps part of the cylinder. The grain is rubbed out against it and falls through it.
Beater Just behind the cylinder. It strips the straw off the cylinder and sends it onto the straw walkers.
Straw walkers These are long shaking racks. They kick the straw up and back to the rear while the last grain falls through them.
Grain pan The pan under the concave. Grain and chaff fall onto it, and it carries them back to the chaffer.
Chaffer It is the upper sieve. It shakes so that grain sifts through its openings while chaff is tossed to the rear.
Sieve The lower sieve, under the chaffer. Clean grain falls through it to the grain auger.
Fan Blows air across the chaffer and the sieve. The air carries off what is lighter than the grain.
Grain auger Clean grain falls into its trough. It carries the grain across to the elevator that fills the tank.
Tailings auger Heads that are not yet threshed fall into its trough. They are carried back to the cylinder to go through again.

How this list was compiled: Part names checked on 2026-09-30; a name is kept only when two independent sources use it. (1) US Department of Agriculture, Farmers' Bulletin 1761, Harvesting with Combines, 1955 edition, https://archive.org/details/CAT87204805 (header, reel, cutter bar, augers on the platform, feeder house, threshing cylinder, concave, beater, straw walkers, grain pan, chaffer, shoe sieve, fan, tailings auger, grain tank). (2) Indian Standard IS 8122 (Part 1): 1994, Test Code for Combine Harvester-Thresher, Terminology, https://archive.org/details/gov.in.is.8122.1.1994 (its definitions of header, reel, cutter bar, cylinder, concave, rear beater, straw walker, chaffer, cleaning sieve, blower, grain auger, tailing auger, grain tank, straw choppers). (3) A maker's instruction book for a combine, https://archive.org/details/manualzilla-id-5954221 (reel, table auger, threshing cylinder, concave, rear beater, straw walkers, grain pan, chaffer, sieve, fan, grain auger, grain tank, unloading auger, straw chopper, cab). (4) Wikipedia, Combine harvester, text only, https://en.wikipedia.org/wiki/Combine_harvester (header, reel, cutter bar, header auger, feeder house, concave, straw walker, grain pan, fan, sieves, grain auger, grain tank, straw chopper, cab, unloading auger). No maker is named. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; own work, no maker's model copied. Licence: own work

How it works

These are the parts of a combine of the conventional kind, which threshes grain with a cylinder and straw walkers. The first view is the machine from the side. The second is the same machine cut open, so the path of the crop shows.

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Outside, front to back

The reel sweeps the crop against the cutter bar at the front of the header, and the feeder house carries it up into the body. The operator sits in the cab. Clean grain ends in the grain tank and leaves by the unloading auger; straw leaves through the straw chopper.

Inside, following the crop

The header auger feeds the crop in. The cylinder threshes it against the concave, and the beater passes the straw to the straw walkers. Grain drops to the grain pan, then through the chaffer and the sieve while the fan blows the chaff away. The grain auger takes clean grain; the tailings auger sends the rest round again.

Chaffer on top, sieve below it, fan in front of both.

Questions and answers

What are the main parts of a combine?

A header with a reel and cutter bar to cut the crop, a feeder house, a cylinder and concave to thresh it, straw walkers to separate the straw, a chaffer, sieve and fan to clean the grain, and a grain tank with an unloading auger.

What is the difference between the cylinder and the concave?

The cylinder is the turning drum with bars round its rim. The concave is the curved grate fixed under it. The crop is threshed in the gap between the two, and the grain falls through the concave.

What do straw walkers do?

Straw walkers are long shaking racks behind the cylinder. They kick the straw up and back toward the rear of the machine, and the grain still mixed in the straw falls through them.

What is the difference between the chaffer and the sieve?

Both are flat screens that shake. The chaffer is the upper one and does the first cleaning. The sieve is below it and finishes the job; clean grain falls through it to the grain auger.