Thresher types: Multi-crop, spike-tooth and axial-flow
Threshers are classified based on the mechanical structure of their threshing cylinder and crop compatibility.
Primary thresher categories in India:
- Spike-tooth threshers: Cylinder fitted with rigid steel spikes rotating against a concave grate, ideal for wheat, barley, and tough dry crops.
- Rasp-bar threshers: Cylinder fitted with grooved steel bars that rub crop heads against the concave, minimizing grain cracking in delicate pulses and soybean.
- Axial-flow threshers: Crop moves spirally along the axis of the cylinder, providing continuous gentle threshing optimal for paddy (rice).
- Multi-crop threshers: Versatile machines equipped with adjustable cylinder speeds, interchangeable concaves, and modular sieves to thresh wheat, mustard, gram, soybean, and maize.
Mechanical working principle and grain cleaning
The threshing sequence separates clean grain through coordinated mechanical stages:
Internal operational phases:
- Feeding hopper: Crop stalks are fed into the hopper, where feed rollers deliver material to the high-speed threshing cylinder.
- Impact and rubbing: Centrifugal impact and rubbing between cylinder teeth and concave grates detach grain kernels from ears.
- Winnowing blower: High-speed aspirator fans create an air stream that blows away lightweight husk, dust, and chaff.
- Oscillating screen deck: Multi-tier eccentric sieves grade clean grains into delivery chutes while directing unthreshed heads back for re-threshing.
Operator safety standards (IS 9020) and SMAM subsidies
Threshers must comply with mandatory Indian Standards (IS 9020) safety regulations, featuring extended feeding chutes and reverse safety covers to prevent hand entanglement injuries. Under the Sub-Mission on Agricultural Mechanization (SMAM), individual farmers can receive 40% to 50% capital subsidies on certified threshers. Verify FMTTI test certificates on agrimachinery.nic.in.
Official source
Check the latest rules, benefits and forms here. KisanPe is an independent platform and is not a government website.
Sub-Mission on Agricultural Mechanization (SMAM) ↗Related on KisanPe
Common questions
What is the primary function of an agricultural thresher?
A thresher separates grains or seeds from harvested crop stalks, ears, and husks, cleaning and bagging the grain.
What is a multi-crop thresher?
A multi-crop thresher is an adaptable machine that can process multiple crops (wheat, soybean, mustard, gram) by changing concave screens and cylinder speeds.
Why are safety feeding chutes mandatory on threshers in India?
Extended safety chutes prevent the operator's hands from reaching the high-speed rotating threshing cylinder, preventing severe injuries.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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