Lec 13 Flashcards
Process of gathering the useful portion of the crop from the field.
Harvesting
In general usage, it includes an immediate post-harvesting, all
of the actions taken immediately after removing the crop – cooling, sorting, cleaning, packing –up to the point of further on-farm
processing, or shipping to the wholesale or consumer market.
Harvesting
Cutting the panicles and straw.
Cutting
(optional), Leaving the cut crop in the field and exposing it to the sun for drying.
Field Drying
Moving the cut crop to the threshing location.
Hauling
(optional), Temporarily storing the harvested crop in stacks or piles.
Stacking/Piling
Removing immature, unfilled and non-grain materials.
Cleaning
Separating the paddy grain from the rest of the cut crop.
Threshing
Also termed as hand reaping, it includes plucking the ears of grain directly by hand, cutting the grain stalks with sickle, cutting them with a scythe, or with a later type of scythe called a cradle
Hand/Manual Harvesting
Harvesting done by employing a mechanical reaper or reaping machine is termed as mechanical harvesting.
Mechanical Harvesting
Manually operated tools used by farmers from planting operation up to
harvesting operation. A human powered instrument or implement usually without parts that
move relative to one another used to facilitate mechanical manual
operations.
This technology is the most basic level of mechanization where a human is the source for power using simple tools and implements.
Hand Tools
A machine that cuts the standing crop, conveys the cut crop to one side, and lays them down in an orderly manner.
Reaper-windrower
A machine that cuts the standing crop, binds the cut crop, and lays down the bound crop to one side.
Repear-Binder
Free grains that fall with the cut stalks during delivery and release at the side of the reaper during operation.
Conveying Loss
Grains that have fallen to the ground due to the
machine’s cutting operation.
Header Loss
Cutting mechanism consists of planetary type circular saw-toothed blade which rotates at the same time with the pick-up triangular frame.
Rotary Knife
Classifications of Reapers: Based on Cutting Mechanism
- Reciprocating Cutter Knife
- Rotary Knife
Classifications of Reapers: Based on Transmission System
- Belt Drive
- Gear Drive
Cutting mechanism consists of fixed lower knife and reciprocating upper knife wherein its movement is controlled by the crank connected to the gear box or belt drive.
Reciprocating Cutter Knife
Cutting mechanism consists of fixed lower knife and reciprocating upper knife wherein its movement is controlled by the crank connected to the gear box or belt drive.
Reciprocating Cutter Knife
Employed in hand tools.
Slicing/tearing action
Use of sharp or dull edged blades moving at high velocity of 2,000 fpm to 9,000 fpm
High velocity, single-element, impact action
Shearing action between the moving and stationary blades
Two-element, scissor type action
Process of separating the grains from the straw.
Additionally, it may include cleaning the grains.
Threshing
Grains are detached from their panicles because of a rubbing action as in treading by man, animal and vehicle. Output of man treading is 14 kg/h
Rubbing action
Grains are accelerated faster than their panicles and are detached as in hampasan and mechanical threshers. Output of hampasan is 34 kg/hr. Output of mechanical threshers vary with
size of machine and power source.
Impact action
Grains are detached from their panicles when the straw is pulled through a “V” configuration or a comb-like device is passed through the panicles.
Stripping action
Manual as in pedal thresher or power thresher as in engine-driven thresher.
Power source
Type of thresher wherein the panicles of the cut
plants are fed into the threshing chamber while the stacks are mechanically or manually held during the threshing operation. Straws do not pass through the threshing section. Low power requirement. Lightweight construction.
Hold-on type
Type of thresher which detaches the grains by feeding the cuts plants into the machine. Straws pass through the threshing section. High power requirement. Heavyweight construction.
Throw-in type
Classification of Thresher, Methods of Feeding
- Hold-on Type
- Throw-in Type
Direction of Threshing Materials
- Axial Flow Type
- Tangential Flow
Materials are fed between the revolving cylinder and stationary concave on one end, go around the cylinder several times axially and discharge at the other end. About 90% of the grains are separated from the straw at the cylinder.
Axial flow type
Materials are feed between the revolving cylinder and stationary concave and go straight out of the
thresher tangentially.
About 60% of the grains pass through the concave and the rest are separated in subsequent
operations.
Tangential-flow
Threshing Cylinder
- Peg-tooth cylinder
- Rasp-bar cylinder
- Wire- loop cylinder
Type of threshing cylinder wherein the spikes or pegs are attached
on the periphery of the cylinder in tandem or in helical arrangement.
Peg-tooth cylinder
Type of threshing cylinder wherein threshing is done between bar-like protrusions in parallel orientation laid on the periphery of the cylinder and stationary bars built into or attached to the concave grate.
Rasp-bar cylinder
Type of threshing cylinder wherein wires of the same arc or size
are attached on the periphery of the cylinder in tandem arrangement with
or without the threshing concave.
Wire- loop cylinder
