DEVELOPMENT AND PERFORMANCE EVALUATION OF SELF

PROPELLED VERTICAL CONVEYOR REAPER

INTRODUCTION

Rice is a major crop of Maharashtra. The area under rice cultivation in

Maharashtra 2008-09 is 1.5 Mha and production is 2.234 MT and yield is 1501 kg/ha

(Anonymous, 2010). Rice harvesting is done manually using sickles which involves 18

man-days/ha. Because of civilization and industrialization labours are not available

during harvesting season, so that the cost of labour during harvesting season is the serious

problem for farmers. It is estimated that harvesting and threshing of crops consume about

one third of the total requirement of production system (Prasad et al. 2007).

Timely harvest of the crop is making to achieve better quality and higher yield of

the crop. The shortage of labour during harvesting season and uncontrolled weather

condition cause greater losses to the farmer. It is therefore essential to adopt the

mechanical methods to ensure timeliness in harvesting operation, minimize losses and to

increase the production in the farm. The land holding capacity of farmers is low, so that

there are fewer margins for the machines like combine harvesters. But now days self

propelled walk behind type reaper becomes popular in such type of field conditions.

Working speed of reaper is equal to twenty labours with sickles. The self propelled

vertical conveyor reaper is designed and developed under collaborative project between

Dr. B.S.K.K.V. Dapoli and M.A.I.D.C. Mumbai, which is to be evaluated.

MATERIALS AND METHODS

Design of self propelled reaper

Design of crop cutting unit of self propelled vertical conveyor reaper

1) Length of cutter bar (Lc): Length of cutter bar is selected on the basis of the row to

row spacing of cereal crops. Generally, length of cutter bar is in between 1-3 m. If length

of cutter bar is less than 1m, it creates hindrance in collection and bundling of crop. So

cutter bars length Lc = 1.2 m is selected.

2) Type of cutter bar: A reciprocating type cutter bar having standard knife section of

76.2 mm stroke length and two cuts per stroke is selected.

3) No. of knife section: =

= cm

= 15.74 ≈ 16 cm

4) Velocity of knife section: The cutting stalk is greatly affected by knife speed. The

velocity of knife section is expressed as

Vk = R× Vm

Where,

Vk = avg. knife velocity, m/s

Vm = forward speed of machine, m/s, 0.69

R = velocity ratio, 1.4

Vk = 1.4 ×0.69

Vk = 0.966 m/s

Also we know that Vk =

X = stroke length

Nk = rpm of knife section

Nk =

Nk =

Nk = 380.31 rpm

For standard 76.2 mm knife section, the above velocity translates into 760.62 stroke/ min.

Now, engine rpm = 3600

Assume speed reduction of 1:3 from engine to intermediate shaft, 1:1.3 from intermediate

shaft to counter shaft and 1:1.6 from counter shaft to the bevel gear box. Therefore, knife

rpm (Nk) is given by Nk =

Nk = 556.87

The actual avg. knife speed of cutter bar of self propelled reaper would be

Vk =

Vk = 1.41m/s

5) Forward speed of machine:

Engine having 3hp power, 3600 rpm.

Outside diameter of wheel = 0.60m

The speed reduction at 3 stages and overall transmission speed ratio of 164.73:1

Vm =

Vm =

Vm = 0.686 m/s

Therefore forward speed of VCR = 0.686 m/s

=

= 2.4696 km/hr.

6) Design of crop divider and lifters

For lifting and conveying crop to cutter bar, the size of crop lifter = 30cm.

Therefore, No. of crop star wheel type crop lifters =

=

= 4

The inclination of star wheels should be 200 and velocity of star wheel should greater

than or equal to forward speed machine. Velocity of star wheel (Vw) is given by

Vw >

Vw = avg star wheel velocity.

Vm = machine forward velocity, m/s

α = angle of inclination of star wheel (20 - 220)

Vw =

Vw = 0.7332 m/s

Vw > Vm.

Outer diameter of star wheel = 280 mm

Inner diameter of star wheel = 140 mm

Material of star wheel = plastic

7) Design of crop conveyor:

The rate of cut crop conveyed by the conveyor should be greater than the crop cut by the

cutting unit of reaper.

a) Speed of lugged belt and diameter of pulley

Vb =

where, Dp = diameter of lugged belt pulley, 0.15 m.

Np = rpm of lugged belt pulley.

Vb = Peripheral speed of flat belt, 1.5 m/s.

Np =

Vb =

Vb =

So the speed ratio would be =

= 2.09

Assume no. of teeth of sprocket on driving shaft = 11 teeth

So, no. of teeth of sprocket on conveyor shaft = 2.09 × 11 teeth.

= 22.99 teeth

b) Length of lugged belt

Length of cutter bar = 120 cm.

Now, centre to centre distance (C) between driving and driven pulley is given by,

C = + 110 +

C = 126 cm.

The length of belt is given by

L = 2C + (π× (D + d)/2) + (D - d)2 /4C

L = 2×1.26 + 3.14 (0.16 +0.16)/2

L = 2.52 +0.50

L = 3.022 m

c) Pitch of lugs:

π × Ds = P× Ns

P =

P = 0.12 m

No of lugs on conveyor belt =

= = 25.18

8) Power requirement of vertical conveyor reaper

Total power for operation of self propelled reaper is given by equation.

Wm = Wr + Wn + Ww

Where, Wr = Power for rolling machine, w

Wn = Power for no load working parts of machine, w

Ww = power required for pull load working of machine, w

Power for rolling of machine (Wr) is given by,

Wr = P×V / ήr × ns

Where, P = resistance to rolling of machine, N

ήr = transmission efficiency, %

ήs = Coefficient of skidding of machine.

The power required cutting crop at a knife speed of 1.41 m/s of cutter bar taken as 0.513

hp/m length of cutter bar power required for conveying cut crop as 50% of the cutting

power. For 1.2 m length of cutter bar = 0.513 × 1.2

= 0.615

Therefore, power required for pull load working of machine (Ww) = Wc + W con.

Ww = 0.513hp = 50 % 0.513 hp.

= 0.513 + 0.2565

= 0.7695

Power for rolling of machine (Wr) is estimated as Wr =

Let coefficient of rolling resistance be 0.2 and weight of machine as 270 kg operating at

forward speed 0.69 m/s

Wr =

Wr = 0.4968 hp

Total power = Ww + Wr

= 0.7695 + 0.4968

= 1.2663 hp.

Assuming 70 % power transmission efficiency at each stage.

Therefore power requirement of self propelled vertical conveyor reaper =

= 1.809 hp.

Therefore 3 hp engine will be adequate to operate the machine in the actual field

condition for harvesting crop. Self propelled vertical conveyor reaper is shown in Fig. 1

Constructional details of self propelled vertical conveyor reaper

Frame

The engine, gear box and handle of reaper were placed on the frame of self

propelled reaper. Frame was fabricated from MS angles of size 50 × 50 × 5 mm. The

frame was made capable in order to bear the weight of gear box, reaping unit and an

engine. The strength of the frame was insured considering the weight of those three units

and the moments coming in static and dynamic conditions. Engine was fitted to the frame

with the help of two MS plates of size 300 × 37.5 × 5 mm. MS pipes of diameters 35 mm

were used as handles. The handles were fitted to the frame using the nuts and bolts of size

3/8. The handle height of reaper was adjustable to suit the maximum user population.

Power unit

The power requirement for the reaper was calculated in order to cross check

whether 3 hp petrol starts, kerosene run engine was adequate or not. Accordingly the

power required to operate the reaper having 1.2 m working width at speed sufficient to

Fig. 1 Top view of self propelled vertical conveyor reaperget the desired field capacity was calculated as 1.8 hp. Therefore, 3 hp engine was found

adequate to operate the reaper. The engine was fitted on the frame at one side. The power

was transmitted to gear through old ham coupling in order to take care of misalignment

between the shafts if any.

Gear box

The rated speed of engine as 3600 rpm of engine is reduced up to 30 rpm at

transmission wheel and 891.4 strokes per min at reaping unit with the help of gear box

and power transmission system. Gear transmission system is designed for the self

propelled reaper. Constant mesh type gear train is designed as per calculations. There are

two speeds in transmission of wheel one is forward and another is reverse.

Gear box assembly is shown in Fig 2, consisted of three sections. In first section

engine speed of 3600 rpm is reduced up to 891.4 rpm using two pairs of constant meshed

helical gears. The four helical gears in the first section viz. A1, A2, A3 and A4 were

having number of gear tooth as 15, 45, 26 and 35 respectively. Hence, the gear train in

the first section had speed ratio as 0.247. The output from second section was directly

connected as an input for reaping unit. The dog clutch was provided to engage or

disengage the power transmission between gear box and reaping unit. The first section

was connected to second section. The second section had two pairs of constant meshed

helical gears made up of four helical gears viz. B5, B6, B7 and B8 having 15, 60, 15 and

60 number of tooth respectively. The speed ratio of this section was 0.0625. Hence, the

speed at output shaft of this section was 55 rpm. A dog clutch was similar that of the first

section used to engage/disengage the power transmission between the second and third

section.

The third section had combination of three bevel gears viz. C8, C9 and C10 with a

sliding collar. Gear C8 had 20 teeth while gear C9 and C10 each had 25 teeth. Sliding

collar engaged one of the two bevels e.g. C9 or C10 at a time. Gear shift lever was

provided to operate the sliding collar. That arrangement had provided the reverse or

forward motion of the reaper. The speed ratio of this section was 0.8. Hence, the speed at

output shaft of the gear box was 44 rpm. Total weight of gear box was 61 kg. Gear box

body was made from 5 mm thick MS plate.

Chain and sprockets were used to transmit the power from gear box to the axle of

wheel. Two sprockets, S1 and S2 with 17 and 35 number of teeth were fitted on the gear

box output shaft and wheel axle respectively. The speed at wheel axle was 22 rpm, as the

speed ratio of chain and sprocket combination was 0.5.

A special feature, dog clutch was incorporated at transmission wheel axle at left

hand side (of operator). It disengaged power from axle to left wheel at the time of

turning. Hence, the reaper could turn safely with less effort by operator. Two pneumatic

wheels of 6-12 size were used for self propelled reaper. As the speed at wheel axle was

22 rpm and diameter of wheel was 60 cm, the travel speed of reaper was 2.5 km/h.

The power from gear box to the reaping unit was transmitted through the

propeller shaft. One more small gear box with two bevel gears was fitted to the reaping

unit to transfer the power in right angle. As the bevel gears were having same number of

teeth i.e. 12 the speed ratio was 1.

Fig. 2 Layout of gear box of self propelled vertical conveyor reaper

Reaping unit

Reaping unit was consisted of cutter bar, crop divider, star wheel and pair of

lugged conveyor belt Fig. 3. Reaping unit cut the crop and conveyed vertically to one end

and windrowed in the uniform swath on the ground uniformly. Cutter bar cut the crop by

impact and shear action between knives and finger guard. The reciprocation of cutter bar

was achieved by the motion from pitman arm. Pitman arm converted the rotary motion

into reciprocating motion. Cutter bar was having 7.2 cm stroke length. There were two

strokes per revolution of the crank. Total length of cutter bar was 1.2 m. Cutter bar was

made of cast iron and that of blade high carbon steel.

During harvesting, the crop divider entered the standing crop, guided it towards

the cutter bar. Lugged belt was powered from reaping unit gear box by chain and

sprocket. Total length of belt was 3.0 m and lug pitch was 12 cm with 25 lugs. The belt

and lugs were made of canvas and plastic respectively. The cut crop was conveyed to one

side by the lugged conveyor belt and star wheels vertically. The star wheels were made of

plastic fitted at 220 inclinations. The diameter of star wheel was 28 cm. The weight of

whole reaping unit was 89 kg.

Fig. 3 Reaping unit of selected self propelled vertical conveyor reaper

Performance evaluation of self propelled vertical conveyor reaper

The performance of self propelled reaper was evaluated by harvesting Karjat-3

variety of rice crop at trial cum demonstration farm of Repoli and Central Experiment

station, Wakawali as per RNAM test code. As per RNAM test code of self propelled

reaper, total 5 plots of size 0.2 ha are to be harvested in field performance test. In Konkan

region, rice field is in the form of small plots and the plots of size equal to or more than

0.2 ha are rarely available. Hence from the available plots six largest plots were selected.

The sizes of those plots were 1060, 1849.43, 832.97, 1639.57, 1200, 804.60 m2. Hence,

the average plot size was 0.12 ha and total area harvested by reaper was 0.74 ha. The

maturity of crop was suitable for harvesting with straw moisture content as 46.43 %. The

trials were conducted in the months October and December, 2010. The crop parameters

as the plant height, grain moisture content and crop yield were measured. The machine

parameters as speed of operation, effective field capacity and fuel consumption were

calculated. In addition to that the pre harvest loss and post harvest loss were also

calculated and tabulated.

RESULT AND DISCUSSION

Performance evaluation of self propelled vertical conveyor reaper

The self propelled vertical conveyor reaper was evaluated at Trial cum

demonstration farm, Repoli and Central experiment station, Wakawali in accordingly

RNAM test code. The Karjat-3 variety of rice crop was harvested by self propelled

vertical conveyor reaper. The calculated crop parameters of harvested crop and field

performance of self propelled vertical conveyor reaper are given in tabulated form in

Table 1 and Table 2. In case of crop parameters the average values of plant height, grain

moisture content, straw moisture content, length of ear head, no. of grains per ear head,

number of plant per m2, no. of tillers per plant, crop yield (kg/ha), grain yield (kg/ha) and

grain crop ratio were calculated. The mean value of plant height of harvested crop was

75.30 cm. The mean value of grain moisture content was 16 % on (wb). The straw

moisture content of cut crop was 46.43 (wb). The average length of ear head was 20.70

cm and the no of grains per ear head was 130.83. The average no of tillers per plant were

10.83. Spacing of crop was maintained in every plot so that no of plants per m 2 was in the

range of 28 to 35.

The average crop yield of harvested crop was 10959.90 kg/ha and that of grain

yield was 3143.7 kg/ha. Ultimately the average grain crop ratio was 0.34. In field

performance of self propelled reaper, forward speed of machine (km/h), width of cut

(cm), average stubble height of cut crop (cm), harvesting losses (pre and post) in per cent,

area harvested (ha), time required for one ha (h), crop handled (kg/ha) and fuel

consumption of machine (l/h) were calculated.

The harvesting operation was done by keeping forward speed of self propelled

reaper in the range of 2.1 to 2.7 km/h. While evaluation of performance of reaper, the

average forward speed of reaper was 2.48 km/h. The average cutting width of reaping

unit was 115 cm. The average stubble height of crop was 113.33 cm which was cut by the

reaping unit from the ground. The total grain losses at the time of harvesting were 4.28 %

of total grain yield among that pre harvest losses were in the range of 1.4 to 2.3 % of total

grain yield and that of post harvest losses were in the range of 2.1 to 2.94 % of total grain

yield. The mean values of pre and post harvest losses were 1.76 and 2.72 % of total grain

yield respectively.

Table 1Crop parameters of rice crop harvested by self propelled vertical conveyor reaper

Sr.

No.

Parameters Test trials

1 2 3 4 5 6 Mean

1 Date of test 30.10.2010 31.10.2010 31.10.2010 31.10.2010 4.12.2010 4.12.2010

2 Average moisture content (%)

Straw (wb) 40 52.2 57.7 56.2 34.23 38.29 46.43

Grains (wb) 20 17.67 17.4 16.8 14.32 15.21 16.9

Variety of crop Karjat-3 Karjat-3 Karjat-3 Karjat-3 Karjat-3 Karjat-3

3 Avg. plant height (cm) 78.75 75 63.5 60.0 87.4 87.2 75.30

4 Avg. Length of ear head (cm) 20.7 21.5 17.4 17.6 23.41 23.6 20.70

5 Avg. No. of grains per ear head 123 137 126 129 138 132 130.83

6 No. of plant per m2 35 40 35 28 35 35 34.66

7 No. of tillers per plant 10 9 8 9 14 15 10.83

8 Grain crop ratio 0.38 0.36 0.32 0.34 0.33 0.32 0.34

9 Crop yield (kg/ha) 9800 10320 11230 10079.41 12370 11960 10959.90

Grain yield (kg/ha) 3730 3715.2 3593.6 3427 4100 3890 3742.63

Table 2 Field performance of self propelled vertical conveyor reaper

Sr. No. ParametersTest trials

1 2 3 4 5 6 Mean1 Date of test 30.10.2010 31.10.2010 31.10.2010 31.10.2010 4.12.2010 4.12.2010

2 Duration of test (h) 0.7 1.53 0.56 1.03 0.85 0.55 0.87

3Engine speed (rpm)-No load 1130 1130 1130 1130 1130 1130 1130- On load

4 Forward speed (kmph) 2.58 2.66 2.61 2.72 2.13 2.2 2.485 Width of cut (m) 1.2 1.1 1.09 1.15 1.16 1.2 1.156 Av. Stubble height (mm) 100 97 110 102 132 139 113.337 Losses (% of total grain yield)

-pre harvest loss 1.47 1.45 1.46 1.68 2.3 2.2 1.76-post harvest (cutter bar+ uncut) 2.94 2.19 2.17 2.27 2.8 2.8 2.52

8 Mass of crop per m2 (kg) 0.980 1.032 1.123 1.007 1.237 1.196 1.099 Mass of grain per m2 (kg) 0.373 0.371 0.359 0.342 0.410 0.389 0.3710 Grain crop ratio (%) 38.06 35.94 31.96 34.03 33.14 32.52 34.2711 Area harvested (ha/h) 0.1514 0.1206 0.1468 0.1586 0.1411 0.1461 0.1412 Time required for one ha. (h) 6.6 8.29 6.81 6.302 7.08 6.84 6.9813 Crop handled (kg/ h) 1483.72 1244.59 1648.56 1597.10 1745.40 1747.35 1577.7814 Fuel consumption (l/h) 1.05 1.08 0.98 0.95 0.9 0.98 0.99

The average area harvested per hour by self propelled reaper varied in the range

of 0.12 to 0.15 ha/h. The mean value of area harvested by self propelled reaper was 0.14

ha/h. The average time required to harvest one ha area by self propelled reaper was

evaluated and i.e. 6.94 h. The crop handled by the reaping unit at the time of harvesting

was calculated and averaged value was 1577.78 kg/h. The fuel consumed by self

propelled reaper for harvesting of paddy was computed and the average value of fuel

consumption of reaper was 0.99 l/h.

CONCLUSIONS