-AGRICULTURAL ENGINEERING
Paper-11
[nme Allowed: Three Hours) (Maximum Marks · '200 J
INSTRUCTIONS
.
Candidates should attempt Question Nos. 1 and 5 which
are compulsory, and any THREE of the
remaining questions selecting at least
ONE question from each Section.
All questions carry equal marks.
Marks allotted to each part of a question are
indicated against each.
Answers must be.written in ENGLISH only.
Assume suitable data if and
indicate the same clearly in your answer.
Unless indicated otherwise, symbols, notations and
abbreviations have their ·usual meanings.
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SECTION-A
· I. Answer any FOUR questions (not exceeding 150 words
each):10x4=40
spite of a rapid increase in tractor and
mechanical power in Indian farms during the
last decade, the food productivity scenario
has not improved as expected. Give your
comments.
(b)Calculate the theoretical power extracted by
a horizontal axis wind rotor of 5m
diameter operating in a wind regime with
wind velocity of 15 km/h. Take air density as
1·29 kg/m3.
(c)Differentiate between the following pairs in brief:
(i)Indirect injection and direct injection
diesel engines for automotive
applications.
(ii)Traction wheel and towed wheel
field sprayer having a horizontal boom
with 20 nozzles spaced 40cm apart is to be
used for a maximum application rate of
650 litres/ha at nozzle pressure of 500 kPa
and forward speed of 5 km/h. Determine
the required pump capacity in litres/min
assuming 10 per cent of the flow is bypassed under
the above maximum conditions.
(e)Explain with a diagram the transmission of
power from engine to the ground drive
components in a crawler tractor. Why are
these tractors more suitable on undulating terrains
as compared to wheel tractors

2.(a)A 2-wheel drive tractor was tested on a farm
surface and the following data were recorded
Drawbar pull 26·2 kN,
distance travelled for 10 revolutions of driving
wheels at no load 55·8m,
distance travelled for 10 revolutions of driving
wheels at load 46.2
fuel consumed 126 and
time taken=25·8 seconds
Determine the following
(i)drawbar power developed
(ii)per cent wheel slip.
(iii)drawbar specific fuel consumption. 15

(b)Explain the working of a power operated
thresher used for wheat crop giving the
recommended range of cylinder peripheral speed ·
and type of threshing element.· Write down the
expressions to evaluate the threshing efficiency and
cylinder loss. 15
single-phase 230 V electric motor running
at 1400 rpm develops a torque of
3·1 Nm. Calculate the amount of electric
current drawn by the motor, if the phase
angle between the voltage and current is 38 deg
and the power efficiency of the motor is
80 per cent. l0
3.(a)Explain the mechanism of anaerobic fermentation
of organic solids. Suggest the optimum range of
the following operating parameters for increased
biogas -production
(i)solid concentration,
(ii)pH of slurry,
(iii)carbon-to-nitrogen ratio,
(iv)digester temperature, and
(v)retention period. 15
(b)With a schematic diagram explain the fuel supply
system in a tractor diesel engine. Name the two
types of injector nozzles with their applications
in diesel engines. 15

four -cylinder, four-stroke cycle diesel engine
operates at 2000 rpm and uses 7·5 litres of fuel
per hour. What is the average volume in millimitres
of individual injections 10

4.(a)A 2-wheel drive tractor engine develops 22·5 kW
at 2000 rpm. The drive passes via a gearbox
which has a ratio of 5.78 engaged, a
differential. reduction of 4 I arid a final drive
reduction of 5:1. Determine the speed,
torque and power delivered to a single
driving wheel of the tractor if it is moving in a straight line and the overall transmission efficiency
is 80 per cent. 15
self propelled combine with an 8-row corn head
for 75cm row spacing travels at 4 km/h. Loss of
time proportional to area equals 8 min/ha and this
is primarily due to the unloading of the grain from
the combine. If the other losses are neglected,
determine on an area basis, (i)the theoretical field
capacity, and (ii)the actual field capacity. 10
(c)With a simple schematic diagram explain
the working of a tractor drawn cut-and-throw.
type forage harvester having a cylindrical cutter
head. How do you determine the capacity of this
machine 15


SECTION___:.B
Write brief notes on any FOUR of the following
(not exceeding 150 words each) 10x4=40
(a)Linear Variable Differential Transformer(LVDT)
(b)Deep bed drying
(c)Hammer mill
(d)Homogenization of milk
(e)Rubber roll husker.
6.(a)Draw a block diagram showing the operations
performed from receiving to final storage in a
modem rice mill. Explain the basic purpose of each
operation in brief.
bin holds 2000 kg of wet grain containing
500 kg of water. This grain is to be dried to
a final moisture content of 14 per cent (wet basis).
(i)What are the initial and final moisture
contents of grain on dry basis
(ii)How much water is removed during
drying?. 15
(c)What is a thermistor? Explain the temperature resistance
function of a thermistor. 10

7.(a)A Wheatstone bridge circuit uses a strain gauge
of 120ohm resistance with gauge factor of 2·05
in each of its arms where only one of the
gauges is active. The active gauge is mounted
on a mild steel bar which undergoes a strain
of 4x10-4. If the excitation supply voltage is
5V, determine the bridge output. 15
(b)With a schematic diagram explain the working of
a vapor compression refrigeration system
commonly used in dairies. 15
(c)What are the desirable qualities of packaging
materials for milk and ice cream 10

8.(a)A tractor mounted fertilizer applicator is to be used
with an electronic sensor and a microprocessor
based data acquisition system to apply desired
quantity of fertilizer at different locations in a
standing crop. Show the schematic design including
the various elements of the system and explain its
functioning. 15

(b)With a diagram explain the working principle of
a Pitot tube to measure the velocity of a gas flowing
through a pipe. What is the major drawback with
the Pitot tube 10

(c)Draw schematic diagram of a screw conveyer and
label the components. A horizontal screw conveyer
of length 2m conveys wheat grain having bulk
density of 680 kg/m3.The screw diameter, shaft
diameter and pitch length of the screw are 0·50m;
0·30 and 0.45m respectively. If the screw is
completely filled with the grain and rotates at 60
rpm, determine the capacity of the screw conveyer .
in kg/h. 15