Reaper cum-binder

Bar harrow

The bar harrow are of two types;

Ø  Spike tooth bar harrow

Ø  Spring tooth bar harrow

Spike tooth bar harrow

It consists of sections

Ø  The width of section is usually from 1.5 -2.0cm

Ø  The section is rectangular in shape, containing the rods on which pegs or spikes are mounted or welded.

Ø  A number of sections may be used depending upon horsepower available.

Ø  The thickness of peg varies from 0.25 to 0.75 inches.

Ø  The pegs are made of heat treated steel and may be replaced or sharpened when worn out.

Ø  The pegs are slightly tilted from vertical

Ø  No of pigs in a section varies from 20-30

Ø  Length of peg is around 9 inches

Uses:

Ø  It breaks crust of soil formed by beating action of rain and reduce the compaction occurred by human, animal or machinery.

Ø  It smoothes and levels soil surface to some extent

Ø  It stirs soil

Ø  It covers the seed of broadcast

Ø  It penetrates to a depth of about 5 cm

Ø  It can mix up the manure

Ø  It can be used for intercultural operation.

Spring tooth harrow

Ø  It consists of section on which curved bars are mounted

Ø  The thickness of the curved bar is 0.25 to 0.50 inches

Ø  The curved is made of spring steel

Ø  The number of curved bars in a section is around 12

Ø  The number of sections may vary according to horsepower available

Ø  The length of curved bars may be up-to 10 inches

Uses:

Ø  Because of spring action it can move easily on rocks and stones

Ø  Because of curved bars it can pull out weeds

Ø  It can break up crust

Ø  It is used to increase moisture retention capacity of soil

Ø  It pulverizes the soil to greater extent.

Rotavator:

Ø  It consists of number of curved blades fitted on horizontal revolving shaft.

Ø  The shafts rotates with 200-300 rpm

Ø  It is operated with P.T.O shaft of tractor

Ø  Uses and advantages:

Ø  It is used particularly for puddling operations

Ø  It cuts and invert the soil

Ø  It pulverizes the soil

Ø  It mix crop residues and organic matter with the soil. Theses operation like cutting, inversion, pulverization are carried out in one operation.

Limitations:

Ø  It requires more horsepower

Ø  It is expensive implement

Ø  Rotating blades may destroy useful bacteria.

Ø  It is particularly used for puddling operation in rice zone and since it has to work in flooded area, its working parts must be covered.

Ø  It is used for mixing of crop residues in the soil.

Harvesting and threshing

Ø  The basic principle of cutting the crop remains the same as manual harvesting with stickle or scissor i.e two straight blades or serrated blades shear the stalk of crop at certain speed. This action is known as reaping or mowing.

Ø  In Pakistan harvesting machinery is mostly limited for rice and wheat

Ø  The following are three types of harvesting machinery introduced in Pakistan

Ø  Reaper

Ø  Mower

Ø  Reaper- cum-binder

Reaper

A reaper cuts the crop and then moves it to one side to make a windrow. So it consist of a cutter bar assembly and a crop conveying unit

Mower

The mower consist of;

Ø  Cutter bar

Ø  Pitman wheel

Ø  Frame

Power transmission elements

Ø  The cutter bar cuts the crop with the help of reciprocating of knife or blade moving along a stationary blade/knife. The cutter bar is operated through pitman wheel which changes rotary motion of tractor PTO into reciprocating or back and forth motion. The mower is mostly used for to cut grasses as for lawn mowing and fodder such as alfalfa, berseem etc.

Ø  Note:  the basic difference between a mover and a reaper is that it only cuts the crop and lay behind the mower, which is collected by labor or raking machinery, while the reaper makes a windrow of the crop.

Reaper –cum-binder

Ø  It has all the elements of a reaper mentioned above along with bundling and knotting units in addition. The cutter bar cuts the crop with normally serrated blades or knives. The harvested crop is then accumulated in the centre with the help of guards and fingers and is fed in the knotting unit, where bundles are made automatically.

Threshing machinery:

Ø  Threshing is a simple operation of removing grain from the straws but it is defined as processes of separating the grain from the mixture of grain, chaff, impurities, etc and finally grading it for use.

The stationary thresher is commonly used in Pakistan. The mechanism will be discussed later in combine harvester

Combine harvester:

Ø  A combine harvester harvest and thresh the crop simultaneously.

Ø  Practically, all combines consist of the mechanism of a reaper attached to a travelling thresher.

Ø  Most of the combines in Pakistan are self-propelled type and are being used to cut and thresh wheat, rice and sunflower.

                Combines perform the following operations at one time. These are;

Ø  Harvesting

Ø  Conveying of cut crop

Ø  Feeding

Ø  Threshing (separation of grains from straw)

Ø  Cleaning of grains from dust, weeds and chaff.

The main components of the combine harvester are;

Ø  Reel

Ø  Cutter bar

Ø  Augur

Ø  Elevator to cylinder

Ø  Front and rear beater

Ø  Threshing cylinder

Ø  Concave

Ø  Grain elevator to tank

Ø  Straw walkers

Ø  Fan

Ø  Sieve

Ø  Grain tank

                    Ø  Unloading augur