11 - Review Notes - Harvesting and Threshing

 

HARVESTING AND THRESHING MACHINERY Arsenio N. Resurreccion CEAT, UPLB •

 

Harvesting – process of gathering the useful portion of the crop from the field

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Threshing – process of separating the grains from the straw. Additionally, it may include cleaning the grains.

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Systems of harvesting and threshing of rice:

1.

Manual harvesting •  Use of hand tools: sickle, scythe, yatab •  80 – 160 man-hrs/ha

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Manual threshing Use of flails or sticks Hampasan Foot threshing

Animal treading 140 – 220 man-hrs/ha   Field losses = 5 – 16% Manual harvesting Mechanized threshing Same as above Use of pedal thresher at 100     man-hrs/ha Power thresher at 12 man  hrs/ha   Field losses = 3 – 10 % Mechanical harvesting Mechanical threshing Same as above Use of manually-operated     •

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3. •

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harvester at 50 manhrs/ha Power harvester at 5 man  hrs/ha Field losses = 3 – 6 %   Combine harvesting – both operations done by a single machine – combine 3 – 21 man-hrs/ha   Field losses – 1.5 – 6 %   Stripping harvesting – removal of grains from panicle without cutting the straw - stripper •

4.

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5.

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3 – 21 man-hrs/ha Field losses = 2 – 6 %

 

 

Figure 1.

Traditional harvesting, threshing and cleaning

 

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Operations done by a combine and stripper: COMBINE 1.  Separating the rows 2.  Cutting the standing crop 3.  Conveying the cut materials into

STRIPPER 1.  Separating the rows 2.  Stripping 3.  Cleaning the grains

the threshing section 4.  Threshing 5.  Shaking the straw to separate loose grains from the straw 6.  Cleaning the grains of chaff 7.  Conveying the grains to the tank or sack

4.  Conveying the grains to the tank or sacks

Factors affecting choice of system: 1.  2.  3.  4.  5.  6.  7. 

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Kind of crop Timeliness of operation Topography Farm size Type of culture (row or broadcasted, upland or lowland) Availability and cost of labor Availability of capital

A major factor affecting choice of system is timeliness of operation  because it affects field losses, time available for the next crop and grain quality Time of harvesting

Field losses (%)

           

One week before maturity At maturity One week after maturity Two weeks after maturity Three weeks after maturity Four weeks after maturity

0.77 3.35 5.63 8.64 40.70 60.46

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If the crop is harvested too early, it will have a large percentage of imperfectly formed kernels.

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The field should be drained 1 – 1.5 weeks before harvesting to harden the

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soil

 

HARVESTING MACHINERY •

 

Groupings of harvesters: 1. 

Hand tools – include the sickle, scythe, yatab, lingkao and cradle (Figure 2)

Figure 2.

Harvesting hand tools

 

2. 

Reaper-windrower – a machine that cuts the standing crop, conveys the cut crop to one side, and lays them down in an orderly manner (Figure 3).

Figure 3. 3. 

Reaper-windrower

Reaper-binder – a machine that cuts the standing crop, binds the cut crop, and lays down the bound crop to one side (Figure 4).

Figure 4.

Reaper-binder

 

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Cutting mechanisms: 1. 

Slicing/tearing action – employed in hand tools (Figure 5)

Slicing action (Sharp smooth edge)

Tearing action (Serrated edge)

Figure 5. 2. 

Slicing and tearing action

High velocity, single-element, impact action – use of sharp or dulledged blades moving at high velocity of 2,000 fpm to 9,000 fpm (Figure 6)

Figure 6.

High velocity, single-element, impact action

 

3. 

Two-element, scissor type action – shearing action between the moving and stationary blades (Figure 7).

Figure 7.

Double-element Scissor type action

THRESHING MACHINERY •

 

Methods of threshing: 1. 

Rubbing action– grains are detached from their panicles because of a rubbing action as in treading by man, animal and vehicle.  

2. 

3. 

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Output of man treading is 14 kg/hr

Impact 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.

Stripping 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.

Mechanical threshers:  

Mechanical threshers employ the impact method

 

 

Variability of threshers come from: 1. 

Power source – manual as in pedal thresher or power thresher as in engine-driven thresher (Figures 8 and 9).

Figure 8.

Pedal thresher

Figure 9.

Power thresher

 

2. 

Type of feeding: a. 

Hold-on feeding – Straws do not pass through the threshing section (Figure 10).  

Low power requirement

 

Lightweight construction Examples: Pedal thresher combine

 

Figure 10.  b. 

and

Japanese

Hold-on feeding type of thresher

Throw-in feeding – Straws pass through the threshing section (Figure 11).      

Figure 11.

High power requirement Heavyweight construction Examples: Axial-flow thresher combine

Throw-in feeding type of thresher

and

US

 

3. 

Direction of threshing materials (Figure 12): a. 

Tangential-flow – Materials are feed between the revolving cylinder and stationary concave and go straight out of the thresher tangentially.  

 b. 

About of rest the are grains pass inthrough the concave60% and the separated subsequent operations.

Axial-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.

Figure 12.

Flow of materials

 

4. 

Types of cylinder teeth (Figure 13): a.  Wire-loop  b.  Peg-tooth c.  Rasp-bar

Figure 13. •

 

Types of threshing teeth

Cleaning systems:  

Separation of the bulky straw, chaff, empty kernels and very light impurities from the grains.

 

Light materials can be separated from the grains by winnowing using natural wind or blower.

 

For hold-on threshers, straws do not pass through the thresher and only the removal of the chaff and light materials are needed using  blowers and screens

 

For throw-in threshers, straws pass through the thresher and cleaning is done using a straw walker, blower and screens.

 

Sample problem 1: A 5-m self-propelled combine makes an average stop of 4 minutes everytime its 2-ton grain grain tank is to be unloaded. The yield of the 20-ha field is 40 tons. The operating speed iiss 4.8 kph. The time for turning on the headland at the ends of the 500-m field is 15 seconds. Find:

a.  b. c.

theoretical field capacity actual field capacity Field efficiency

Solution: a) 

Theoretical field capacity = C T = =

 b) 

Actual field capacity = C A =

A

SWEff 

where Eff = 1.0

10

(4.8 kph)(5 m)(1.0)  = 2.4 Ha/hr 10 where

T

A = 20 ha T = t 1  + t 2  + t 3   where t1  = actual working time in the rows at 100% efficiency t2  = time for turning at headland t3 = time for unloading of tank   400 m  No. of rows = N R  = = 80 rows 5m/row t1  = 80 rows X 500 m/row X 1km/1,000m X 1/4.8 kph = 8.333 hr t2  = 80 rows X 1 turn/row X 15 sec/turn X 1 hr/3600 sec = 0.333 hr 1 X 4 min/tank X 1 hr/60 min = 1.333 hr t3  = 40 tons X 2 tons/tank  T = t 1  + t 2  + t 3  = 8.333 hr + 0.333 hr + 1.333 hr = 10 hr C A  = c) 

A T

=

20 ha  = 2 ha/hr 10 hr 

Field efficiency =

C

A  X 100 = C T

2  ha/hr 

 = 83.33 %

2.4 ha/hr 

 

Sample problem 2: A 4-m combine travelling at 5 kph can empty its 1.64-ton grain tank in 60 seconds. When u unloading nloading on-the-go, it h has as an 82% field efficiency. Field yield is 3 tons/ha. Find: What would b bee the field efficiency if the combine stopped to load? Solution: a) 

Unloading on-the-go: Actual field capacity (on-the-go) =

 b) 

SWEff  10

(5 kph)(4 m)(0.82)   10 = 1.64 ha/hr

 =

 No. of unloadings/hr = 3 tons/hr X 1.64 ha/ ha/hr hr X

1   1.64 tons/load 

= 3 unloadings/hr c) 

Time for unloading = t 2 = 3 unloadings/hr X 60 sec/unloading   = 180 sec

d) 

t Eff = 1   T

 

t 1 = operating time = Eff X T

→

  = 0.82 X 3600 sec = 2952 sec e) 

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t 1  New Eff = T+t

 X 100 = 2

2952 sec  X 100 = 78.10 % 3600 sec + 180 sec

Reading Assignment: 1.

PAES 204:2000

2.

PAES 205:2000

3.

PAES 212:2004

4.

PAES 213:2004

Agricultural Machinery – Thresher – Specifications Agricultural Machinery – Thresher – Methods of Test Agricultural Machinery – Specifications Agricultural Machinery – Methods of Test

Mechanical Rice Mechanical Rice Rice

Reaper

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Rice

Reaper

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Harvesting Equipment Questions

1. 

2. 

The traditional system of harvesting and threshing of rice is: a.

manual harvesting and threshing

c.

mechanical harvesting and threshing d.

manual harvesting and mechanical threshing combining

Among the factors affecting the choice of harvesting and threshing system, which one is the major factor? a. c.

3. 

b.

kind of crop topography

b. d.

timeliness of operation farm size

The threshing action most commonly employed by a mechanical thresher for rice is: a. c.

4. 

b. d.

impact action all of the above

A 4-m combine traveling at 5 kph can empty its 1.5-ton grain tank in 2 minutes. When unl unloading oading on-the-go, it h has as an 86% field field efficiency. Field yield yield is 3.5 tons/ha. What would be the field efficiency if the combine stopped to load? a. c.

5. 

rubbing action stripping action

70% 80%

b. d.

75% 85%

The conventional system of harvesting and threshing of rice in the Philippines is:

6. 

a.

manual harvesting and threshing

c.

and mechanical threshing mechanical harvesting and threshing d. combining

Manual harvesting

Average harvesting losses of rice at maturity date is 3.35 %, but two weeks after maturity date this will increase to: a. c.

7. 

b.

5.63% 40.70%

b. d.

8.64% 60.46%

The threshing action where grains are detached from their panicles when the straw is pulled through a “V” shaped configuration is called: a. c.

rubbing action str ipping action stripping

b. d.

impact action a and b

 

8. 

What is the theoretical field capacity of a 3-m combine traveling at 100 meters in 52 seconds? a. c.

9. 

0.03 ha/hr 1.45 ha/hr

b. d.

0.57 ha/hr 2.08 ha/hr

A 5-m self-propelled combine makes an average stop of 4 min every time its 2-ton grain tank is is to be unloaded. Gross yield of the 20-ha 20-ha field is 42 tons. The operating speed iiss 4.8 kph. The time ffor or turning on the headland at the ends of the 500-m field is 15 seconds. Find the theoretical field capacity of the combine: a. c.

10. 

1.2 ha/hr 3.6 ha/hr

b. d.

2.4 ha/hr 4.8 ha/hr

The most recently developed system of harvesting and threshing of rice is: a. c.

11. 

13. 

b. d.

combining all of the above

A machine that cuts standing crop, conveys the cut crop to one side, and lays them down in an orderly manner is called: a. c.

12. 

mechanical harvesting & threshing stripping

sickle reaper-binder

b. d.

reaper-windrower stripper

The Japanese combine is characterized as: a.

low power & hold-on feeding

b.

c.

high power & hold-on feeding d.

low power & throw-in feeding high power & throw-in feeding

A 5-m self-propelled combine makes an average stop of 4 min every time its 2-ton grain tank is is to be unloaded. Gross yield of the 20-ha fi field eld is 42 tons. The operating speed is 4.8 kph. The time ffor or turning on the headland at the ends of the 500-m field is 15 seconds. Find the actual field capacity: a. c.

1.5 ha/hr 2.0 ha/hr

b. c.

2.5 ha/hr 3.0 ha/hr

 

14. 

Which of the following operation is not done by a stripper? a. c.

15. 

cutting of standing crop cleaning of grains

b. d.

stripping conveying of grains to the tank

The cutting mechanism most commonly employed by reapers and combines is:

16. 

17. 

a.

slicing & tearing

b.

c.

two-element, scissor-type action

d.

high velocity, singleelement, impact action all of the above

The IRRI axial-flow thresher is characterized as: a.

low power & hold-on feeding

b.

c.

high power & hold-on feeding d.

low power & throw-in feeding high power &throw-in feeding

A 5-m self-propelled combine makes an average stop of 4 min every time its 2-ton grain tank is is to be unloaded. Gross yield of the 20-ha field field is 42 tons. The operating speed iiss 4.8 kph. The time ffor or turning on the headland at the ends of the 500-m field is 15 seconds. Find the field efficiency: a. c.

78% 87%

b. d.

83% 90%