M&E/GHA/Combines/04/05 1

Combine Harvesters

Grain Loss

M&E/GHA/Combines/04/05 2

Combine HarvestersGrain Loss

Zero grain loss is unachievable due to a culmination of circumstances.

The best any operator can hope to achieve is an acceptable level that is consistent with the crop being harvested .

Loss will occur four main areas.

from the ear prior to the combine entering the crop. Field Loss

from the straw walkers. Walker Loss

from the header. Header Loss

from the sieves. Sieve Loss

M&E/GHA/Combines/04/05 3

Combine HarvestersGrain Loss monitors

Cab MonitorStraw Walker Sensor

Sieve Sensor

M&E/GHA/Combines/04/05 4

Combine HarvestersGrain Loss monitors

Grain loss in most combines is monitored by the use of sounding boards.

The boards cover the full width of the straw walkers and sieves.

The grain hits the sensor and this either generates an electric impulse or

a sound wave that is picked up by a microphone

The signals are then transmitted to the monitor in the cab usually appearing as a light signal, bar graph .

With some harvested crops the monitors are not effective due to the straw creating more impulses than the seed.

M&E/GHA/Combines/04/05 5

Throughput

% Loss

A

Grain Loss increases in proportion to throughput.Point A = separation Capacity at concave overload

Combine HarvestersGrain Loss

M&E/GHA/Combines/04/05 6

Combine HarvestersGrain Loss

AB

C D

A = Field Loss B= Header Loss

C = Thresher Loss B = Total Loss

M&E/GHA/Combines/04/05 7

Header Width

YieldKg/ha

2.6m 3.0m 3.3 3.6 3.9 4.5 5.1 5.8 6.7

4,000 228 268 295 322 349 402 456 510 590

4.500 257 302 352 362 392 463 513 573 610

5.000 285 355 369 402 436 503 570 637 738

5.500 314 369 402 443 479 553 627 701 811

6.000 342 402 443 483 523 604 684 764 885

Combine HarvestersGrain Loss

Combine HarvestersGrain Loss

M&E/GHA/Combines/04/05 8

Loss of grain over the sieves. Cylinder speed too high – concave clearance too close causing over

threshing

Adjust speed and clearance.

Ground speed too high.

Incorrect sieve settings

Fan speed to slow/high.

Air diffusers incorrectly set.

Shaker speed incorrect

Excessive returns.

Uneven feed.

Reduce ground speed

Adjust sieves to a wider setting

Adjust fan speed

Adjust diffusers.

Check belts and speed.

Adjust sieves

Combine HarvestersGrain Loss

M&E/GHA/Combines/04/05 9

Straw Walker Loss. Over threshing at the cylinder.

Concave blocked with dirt and mud.

Heavy straw.

Straw walker speed too slow.

Filler bars still fitted.

Straw walker curtains damaged.

Ground speed too fast.

Insufficient feed (thin crop)

Concave too wide.

Excessive returns to cylinder.

Reduce cylinder speed.

Clean out concave

Reduce forward speed.

Check belt adjustment and speed.

Remove filler bars.

Check curtains and replace if necessary.

Reduce ground speed.

Increase ground speed.

Adjust concave.

Adjust sieves

M&E/GHA/Combines/04/05 10

Combine HarvestersYield Monitoring

SignalGrain Flow

M&E/GHA/Combines/04/05 11

Combine HarvestersGrain Damage

Grain sample shows excessof cracked grain.

Cylinder speed too high.

Reduce cylinder speed.

Concave clearances too close Adjust concave.

Grain cracked in returns system.Check returns, if good grain is in the system – open top or bottom sieves.

Slack chains on good grain and/or returns elevator.

Adjust elevator chains.

Filler bars fitted. Remove filler bars.

Sieve settings. Adjust sieves to a wider setting

Combine Harvesters

M&E/GHA/Combines/04/05 12