Fig. 5. Grain pan. chaffer, and chaffer extension (International Harvester Co.)

B. CHAFFER. This is an extension of the grain pan. It has relatively large, adjustable openings. Threshed grain drops through these openings to the cleaning sieve, but unthreshed heads and larger pieces of residue are carried back to the chaffer extension.

C. CHAFFER EXTENSION. This short unit is hinged to the rear of the chaffer. The grain pan, chaffer, and chaffer extension are usually a single unit.

The chaffer extension has adjustable openings that can be raised or lowered. When it is properly adjusted, unthreshed heads fall through the openings into the tailings auger. But large particles and coarse residue are carried out the rear.

In some models there is a tailboard at the end of the chaffer extension. You can raise this, if necessary, to prevent grain from being blown out.