1. Off-Road Equipment Management TSM 262: Spring 2016
LECTURE 20: Grain Harvesting I
Off-Road Equipment Engineering
Dept of Agricultural and Biological Engineering

2. Homework, Lab and exam

3. Grain Harvesting: Class Objectives
Students should be able to:
Understand the terminology pertinent to grain combine design and performance
Identify and analyze the functional processes for cutting, conveying, threshing, separation and cleaning of grain
Evaluate combine harvester performance relative to grain losses

4. Grain Harvesting
Divided into cutting, threshing, separation and cleaning
Threshing
Breaking grain free from other plant material by applying mechanical force
Separation
Separating threshed grains from bulk plant material (straw)
Cleaning
Use air to separate fine crop material such as chaff from grain
Combine – single field-going machine that performs all these operations

5. History Harvesting in its simplest form Recovery of grain from fields
Must be done in a given time frame
Must maintain the quality of the grain
History
Manual labor and Early Machines
Focus was on cutting and gathering
Threshing was done at a later time

6. History (ctd.)
McCormick-Deering introduced combination harvester-thresher ~ 1920
This thresher uses similar processes as modern combines

7. ASABE Standard S343.3 (Compass)
Terminology for combines and grain harvesting
Purpose: “establish terminology pertinent to grain combine design and performance”
Combine components
Crop terminology
Combine performance

8. Functional Processes
grain

9. Functional Processes
Thresh and Separate
Store
Unload
Convey
Gather and Cut
Clean

10. Class problems
(a) An 8-row combine is operating at 3 mph in 30 inch row corn. If corn yield is 160 bu/acre, compute the time required to fill a 240 bu grain tank
(b) A Lexion combine with 16-row corn header is operating at 5mph in 30 inch row corn. If corn yield is 200 bu/acre, compute the time required to fill its 360 bu tank
One acre = ft2
One mile = 5280 ft
Note: This does not include time for turning

11. Solution (a) Given Find time for fill Width = Speed = Corn yield =
Grain tank capacity =
Find time for fill
Work rate =
Bushels per h =
Time for 240 bushels =

12. Solution (b) Given Find time for fill Width = Speed = Corn yield =
Grain tank capacity =
Find time for fill
Work rate =
Bushels per h =
Time for 360 bushels =

13. Grain harvesting System

14. Grain Harvesting Process
Inputs:
grain moisture
MOG
yield
time of day
relative humidity
cleaning fan speed
threshing speed
concave opening
chaffer opening
sieve opening
feed rate
Outputs:
feed rate
threshing loss
separator grain loss
cleaner grain loss
grain breakage
grain dockage

15. Definitions Cleaning loss -free grain in the cleaning discharge
Tailings MOG - amount of Material Other than Grain in the tailings return system, measured as a ratio of the tailings MOG to the discharge MOG
Tailings grain - amount of free grain in the tailings return system, kg/s
Grain damage - number of broken grain kernels, measured as a weight percentage
Dockage - foreign material in the clean grain, measured as a weight percentage

16. Functional Processes Gather Cut Convey Thresh Separate straw Clean
Header
Feeder
House
Threshing
Cylinder
Separator
Gather
Cut
Convey
Thresh
Separate
straw
Clean
chaff
Cleaning
Shoe
grain
Unload
Store
Convey
Unloading
Auger
Grain Tank
Clean Grain
Auger

17. Gathering, Cutting and Conveying
Most general cutting mechanism is grain table (cutting platform, platform, etc.)
Grain Table
Reel
Auger
Sickle

18. Grain Header Reel keeps material from flowing back out
Cutterbar: Sickle, material presented in “hay” lecture applies
Auger: Gathers grain toward the center of the header where it can be conveyed into the combine
Common Adjustments
Reel height, reel speed, header height, reel fore/aft

19. Grain Header Performance
Header losses
Shatter losses-grain lost because of reel
Cutterbar losses-grain cut by cutterbar but falls to ground
Header losses affected by
Cutting height
Reel position (height, fore/aft)
Reel speed
Draper Head

20. 1. End sheet 2. Reel 3. Cutterbar
4. Auger Feeder conveyor 6. Threshing cylinder

21. Finger sensors for cutter bar height control

22. Gathering, Cutting and Conveying
Corn Head
Pulls stalks downward
Ears catch on “snapping rolls/bars”
The spacing on the snapping rolls is wide enough for the stalk to go through but the ear catches and is conveyed into the machine

23. Feeder
conveyor
Snapping rolls
Gathering
chains
Gatherer points

24. Corn header Harvest 4 ~ 18 rows at a time Gathering Chains
Moves stalks through snapping zone
Conveys loose ears
gathering chain speed = forward speed
Snapping Rolls
Ear is separated from stalk
Typical length=1-1.25m;diameter cm
Speed of rotation critical

25. Corn Header Stripper Plates Trash Removal
Prevent ears from contacting snapping rolls
Opening between stripper plates can be controlled from cab on newer combines
Trash Removal
Rolls are fluted on upper ends
Aids in removal of trash and broken stalks

26. Caterpillar corn head row unit

27. Corn Head
Corn pulled downward

28. Corn Head