Topics: Combine harvester, Rice, Cereal Pages: 9 (2406 words) Published: January 19, 2013
Republic of the Philippines
College of Engineering, Department of Agricultural Engineering Science City of Muñoz, Nueva Ecija


By: Allen Denver V. Mangaoil
Bachelor of Science in Agricultural Engineering

January 9, 2012


Harvesting is the process of collecting the mature rice crop from the field. Paddy harvesting activity includes cutting, stacking, handling, threshing, cleaning, and hauling. It is important to apply good harvesting methods to be able to 1) maximize grain yield, and 2) minimize grain damage and quality deterioration. Harvesting can be done manually using sickles and knives, or mechanically with the use of threshers or combine harvesters. Regardless of the method, a number of guidelines should be followed to ensure that good grain quality is preserved during harvest operations and harvest losses are kept to minimum. One of the most common part of the post harvest activity that produce great loss when not properly done is threshing.

This research aims to:
1. Define what is a thresher and its use as a post harvest activity. 2. Identify the different types of threshing practices and operations. 3. Familiarize in the different threshing operations.

4. To know the history of threshing and the development of the modern day thresher 5. And lastly to troubleshoot a thresher.

Threshing Defined
Threshing is the process of loosening the edible part of cereal grain (or other crop) from the scaly, inedible chaff that surrounds it. It is the step in grain preparation after harvesting and before winnowing, which separates the loosened chaff from the grain. Threshing does not remove the bran from the grain. Threshing is the process of separating the grain from the straw. It can be either done by hand, by using a treadle thresher or mechanized by using a machine. Threshing may be done by beating the grain using a flail on a threshing floor. Another traditional method of threshing is to make donkeys or oxen walk in circles on the grain on a hard surface. A modern version of this in some areas is to spread the grain on the surface of a country road so the grain may be threshed by the wheels of passing vehicles.

Figure 1. Manual threshing of rice paddy
Figure 2. Mechanical threshing of rice paddy

However, in developed areas it is now mostly done by machine, usually by a combine harvester, which harvests, threshes, and winnows the grain while it is still in the field.

Paddy thresher
Paddy thresher is the thresher used for threshing paddy. The threshing cylinder is of spike tooth type and the top cover has louvers to guide the crop axially.  In the end of the cylinder there is a thrower for the paddy stalks.  The thresher has also the cleaning mechanism and bagging attachments.  It can be operated by a tractor, diesel engine o electric motor.  The capacity may be 250-1000 kg/hr.  Paddy thresher (Pedal operated)

It consists mainly of a well balanced cylinder with a series of threshing teeth fixed on wooden slats.  It has got gear drive mechanism to transmit power. While the cylinder is kept in rotary motion at high speed, the paddy bundles of suitable sizes are applied to the teeth.  The grains are separated by the combing as well as by hammering action of the threshing teeth.  This thresher mainly consists of: Body frame, Cylinder, Drive mechanism and Axle.  Axial Flow thresher

Table 1: The table shows the different characteristics of an axial flow thresher.

Feeding type| Hold-on (or head feed)| Only the panicle is fed into the machine| Straw remains intact| Lower throughputComplex machine| | Feed-in| The hole crop is fed into the machine| Higher throughput| Clogging with very wet or long straw. Higher power requirement| Crop flow|  

Axial-flow| Whole crop moves axially around the drum...
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