Compilation of Board Exam Problems in

Agricultural Engineering

AGRICULTURAL POWER, MACHINERY & ALLIED SUBJECTS

1. Distinguish the following:

a. Effective tire radius from loaded tire radius

b. Automatic position control from automatic draft control
c. SAE number from Cetane number
d. Drawbar horsepower from PTO horsepower
e. Subsoiling from chisel plowing

2. How is automatic draft control achieved?

3. What soil conditions will favor the use of disk plows over the moldboard
plows?

4. What is the state of +arm mechanization in the Philippines? What should

be done to accelerate farm mechanization?

5. Enumerate and discuss, three +actors that increase the penetration of

trailing disk harrows?

6. What is the difference in the dropping mechanism of corn and cotton

planters?

7. Do you recommend the use of sugarcane harvester in the Philippines?

Defend your answer?

8. A sugarcane fertilizer applicator is to apply 16 bags of fertilizer per

hectare. The fertilizer applicator is to be calibrated by driving the
applicator forward a distance of 200 m. What is the weight of fertilizer
that should be collected from the delivery tube to get the correct
application rate? Assume each bag of fertilizer weighs 50 kg (Show all
computations and assumption*&.

9. The loaded radius of the pneumatic tires of a ground wheel-driven grain

drill is W. The estimated slippage is 18% and the required ground speed
of the grain drill is 7 kph. How many revolutions should the wheel be
turned to achieve this?

10. A corn sheller will be driven by a 10 hp diesel engine through a V-belt

drive. The engine has a speed of 1900 rpm while the required speed *f
the corn sheller is 650 rpm. The effective diameter of the driver pulley
is 120. Calculate the following:

a. Diameter of driven pulley

b. Length of belt.
c. Number of belts required
d. Life of belt in thousand hours,
e. Appropriate shaft diameter for the driver and driven pulleys
(Show all computations, assumptions, and references)

11. A thresher has a capacity of 30 cav/hr. Three men are required

to operate the thresher. the other data are as follows:

Purchase price ………………………………………………. P40,000 including engine

Salary of laborers ……………………………………. P30/day-person
Utilization ………………………………………………………. 1,500 hr/year
Cost of money ……………………………………………….. 212 p.a.
Estimated life …………………………………………….. 7 yr
Size of engine …………………………………………….. 10 hp
Specific fuel consumption ………………….. 0.85 lb/bhp-hr

Calculate the cost of threshing a cavan. of palay. Show all,

computations and other assumptions.
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12. Estimate the number of sugarcane harvesters required to harvest

10,000 ha. of sugarcane under the following conditions:

Harvester speed ………………………………………………….4 kph

Row spacing of sugarcane …………………………..1.5 m
Field efficiency ………………………………………………. 80%
.

Number of working days per month ……… 26

Ave. number of milling months ……………. 5

13. A farmer wishes to irrigate his farm with a centrifugal pump. He

needs to lift 1200 9pm through a vertical. Height of 80 ft. the
lift is through 2,000 ft of 6" B.I. pipe, 4 pc of-6* x 45 elbows
and one 6* gate valve. The pump efficiency is 75%. The specific
fuel consumption of a diesel engine to be used as prime mover Is
0.8 lb/bhp-hr. Calculate the cost of pumping a hectare-inch of
water if the cost of diesel fuel is P5.00/li. (Other head losses
due to fitting is assumed to be 15% of the vertical lift).

17. A group of small farmers would like to put up a new project with
the following assumed data:

a. Total investment required - P60000,000.00

b. Long-term loan:

If from bank X - P49000,000.00 .14 1/2Z

If from Bank Y - 3v000,000.00 14 1/2%
c. Balance of financing, short term loans and stockholders equity
is assumed at 18%.

Problem: a. Determine the cost of money to be invested:

i. If Bank X is to be tapped
ii. If Bank Y is to be tapped.

b. Which bank would you recommend to be tapped? Justify

your answer.

I MULTIPLE CHO1CE. Indicate the best-answer by encircling the

letter oh the special answer. sheet. Submit all solutions to
problems.

1. An irrigation pump shall be driven by a single cylinder diesel

engine. The set up has the following data:

Engine rpm ............a 2,200

Pump rpm ................1, 800
Diameter of engine pulley 25 cm

What should the diameter of the pump pulley be?

a. 35.05 cm b. 30.55 cm c.53.65 cm

2. The length of the flat belt of a Cat-belt pulley drive with

the following data:

Diameter of first pulley ..........300 me

Diameter of second pulley . % ......400 me
Center distance of the pulley shafts ... 10 in
a. 20.1 b. 21.05 c.25.01

3. A term used to describe the resistance of oil to flow

a. viscosity b. cetane number c. volume weight
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4. A primary tillage equipment that is better suited for rough

and rooty ground
a. rotary tiller b. disk plow c. moldboard plow

5. An implement that is used to break hard soils to depth of 50

to'90 c*
a. disk plow b. moldboard plow C. ripper-subsoiler

6. A trailing harrow that is hitched too high to the drawbar

will:
a. have too deep penetration
b. have too shallow penetration
c. have the right penetration

7. A tractor device which will automatically raise or lower the implement

in operation to maintain a given draft:

a. automatic draft control

b. automatic position control
c. none of the above

8. The inherent characteristics of tractors to maintain or produce

increased drawbar pull even if the speed is reduced:
a. lugging ability
b. mechanical efficiency
c. coefficient of traction

9. The actual coverage rate by an implement based on total field time:

a. field efficiency
b. effective field capacity
c. theoretical field capacity

10.The speed of an engine is automatically regulated by:

a. hand lever
b. governor
c. flywheel

11.A moldboard plow has

a. lower draft than diskplow

b. higher draft than disk plow
c. equal draft with disk plow

12.By increasing the disk angle, the penetration of a disk plow

a. will improve
b. will be the same
c. equal draft with disk plow

13.The disk angle that will give the minimum draft for a disk plow for a
given width is:

a. 30-35
b. 40-45 0

c.45-50 0

14. A tractor that is powered by a square diesel engine (bore and stroke
dimensions are equal):

a. has a good lugging ability

b. has a poor lugging ability

15. The lower PTO speed of standard four wheel tractors is:
a.. 540 rpm
b. 450 rpm
c. 640 rpm
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16. Discuss the two features, advantages, disadvantages, and uses of: (a)
rotary plows (b) trailing disk harrows

17. Discuss the procedure in calibrating a corn planter.

18. Explain the meaning and importance of Nebraska Tractor Test.

19. Discuss three (3) advantages offset disk harrows over the tandem
harrows.

20. Do you recommend the full mechanization of corn production in the

Philippines? Why or why not?

21. A farmer wishes to plant his 500 ha farm with hybrid corn. The
following operations shall be mechanized:

Prepation No. of passes Maximum no. of days req’d

to complete operation

Land preparation:
plowing 1 90 days
harrowing 2 75 days
Planting 1 75 days
Spraying as required
Harvesting 1 90 days

Estimate the required number of (a) tractors, (b) corn planters, and
(c) corn picker-sheller and cycle time in days.

Assume: width of cut of 3-bottom disk plow = 120 c* trailing disk harrow =
225 cm corn planters = 4-row unit corn picker-sheller = 1 row plowing,
harrowing speed - 5 kph row spacing - 1 m field efficiency = 75%
planting and harvesting speed - 4 kph

1. Theground speed of field - machinery is a major factor to consider in

controlling the application rate of sprayers, fertilizer applicators
and other field machineries.A quick method of estimating ground
speed is by walking beside the machine and counting the number of
steps made during a specific period of time. If the average length of
man's step is 0.78 my for how many seconds should he walk beside a
field machine so that the resulting number of steps divided by 10 will
indicate the average forward travel in kilometers per hour?

2. A 46-kw four wheel tractor equipped with a three-bottom disk plow is to

be used in a farm where the soil texture is predominantly clay loam.
Each bottom has an effective width of cut of 34 cm and the desired depth
of plowing is 16 cm.

a. Calculate the drawbar power in kilowatt utilized for field operation if

the unit draft of the implement is 90 kPa and the average speed of travel
is 4 kph.

b. What would be the reading in a dynamometer in kilograms placed between

the plow and the hitch if the line of draft passing through the
implement center of resistance and the hitch point of the tractor drawbar
makes an angle of 150 with the horizontal?

c. If the tractor has a mass of 29400 kg with 802 carried by the

front wheels and 1 9 598 kg concentrated at the rear wheels under
static conditions, determine the location of the tractor center of
gravity in millimeters in level ground with respect to the rear
axle if the tractor wheel base is 2,146 mm.
d. Assuming dynamic conditions of equilibrium while plowing under the
preceding conditions, calculate the weight in kilograms transferred from
the front wheels to the rear wheels if the drawbar clearance is 38 cm
from ground level and the vertical component of the load from the plow
lies in a plane 10 cm horizontally from the vertical soil reaction at
the rear wheels. Neglect other minor forces acting on the tractor.
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e. Determine the minimum amount of horizontal load in kilonewtons at the

tractor drawbar under dynamic conditions at which the front wheels start
to leave the ground or cause the tractor to turn over its rear axle.
Neglect rolling resistance and assume positive traction and sufficiency
of tractor engine power.

3. An offset disk harrow of the trailing type is hitched to the tractor

drawbar such that the center of cut of the front and rear. gangs are 250
cm and 410 c&. respectively from-a transverse line passing through the
hitchpoint. The front and rear gangs are adjusted to operate with the
disk blades at angles of'17 0 and 24 % 0 respectively with respect to the
line of travel. Horizontal soil reactions on the front and rear gangs
are indicated as follows:

Longitudinal force on front gang = 4.0 kN

Transverse force on front gang = 3.4 M
Longitudinal force on rear gang = 4.5 kN
Transverse force on rear gang = 4.9 M

From the given data, determine:

a. The magnitude and direction with respect to the line of travel of the
resultant forces acting on the centers of cut of the front and rear
gangs.

b. The transverse distance in centimetres of the centers of cut of the

front and rear gangs perpendicular to the line of travel, reckoned from
the hitch point. Assume that the centers of cut of the front and rear
gangs lie along a straight line parallel to the direction of travel.

c. The total amount of pull in kilonewtons passing through the center of

resistance of the implement and the hitch point at the drawbar.

d. The horizontal angle of pull with respect to the line of travel.

3. In the expanded yellow corn prodution program (Masagana), the

recommended plant population for a popular brand of hybrid corn is
67p000 plants per hectare to be planted in furrows 75 ca apart at a
depth of about 8 cm.

a. Assuming a germination rate of M9 what would be the appropriate spacing

between hills of a single---row animal-drawn corn Planter to be designed
and utilized for hill-dropping at the rate of one seed per hill?

b. The ground wheel of the above planter has an effective radius of 45 c*

and equipped with a sprocket with 40 teeth. The ground wheel sprocket in
turn drives a vertical seed plate with a sprocket of 20 teeth. If the
seed plate is 30 cm in diameter, how many cells would be needed in the
seedplate to achieve the desired planting pattern? What would be the
correct distance between cells in the plate?

c. If the sprockets at the drive wheel and the seed plate were
interchanged, what would be the-spacing and number of cells in the
seedplate to satisfy the same field planting pattern and population?

d. After a number of field tests on the planter described in a bp and cp

adopting a sprocket teeth ratio of 112 (ground wheel to seedplate), it
was noted that a seedplate peripheral speed not exceeding 23.2 cm/sec
would ensure a 100% cell fill. What would be the corresponding speed of
the wheel in kph to avoid gaps in the planting pattern?

4. The crankshaft of a single cylinder 4-stroke cycle spark ignition engine

rotates in a clockwise direction (facing the cranking lever) while in
operation. During normal operation, the intake valve opens 4o after head
center and closes 360 after crank center. The exhaust valve opens at 42 0
before crank center and closes at head center. Ignition takes place at
22 0 before head centre.

a. Describe the events that would take place if by mistake, the engine
was cranked manually in a counter clockwise direction. Specifically, trace
the path of the air before and after leaving the combustion chamber the
action of the valves and breaker points vis-a-vis the movement of the
 6

piston in two revolutions of the crankshaft showing normal operations to

facilitate description of events in the reverse rotation.

A 12 x 15 cm four-stroke vertical gasoline engine has a 43 cm connecting

rod. The exhaust valve of the engine is designed to open at 0 the later part
of the power stroke. If the exhaust valve opens at 39 before bottom dead
center during the power stroke, how far had the piston travelled in
centimeter with respect to its position at top dead center? What percentage
of the stroke had been swept through the piston at this point?

A single cylinder 4-stroke cycle stationary diesel engine with a bore of

7.62 cm and stroke of 10.16 cm was tested in a prony brake to determine its
brake power at 1000 rpm. The dynamometer had a torque arm of 76 c& and a
tare weight of 1.13 kg'.

a. What-was the brake power developed, in kilowatt at the observed engine

speed if the gross weight reading at the scale -was 7.21 kg?

b. What is the value of the brake constan for the particular dynamometer
used in the test?

C. Under the given conditions. how much torque in H was develop at the
engine crankshaft, and what was the corresponding engine brake mean
effective pressure in kPa?

To augment the source of power for pumping water in a poultry fare. an

operator erected a windmill with a wind wheel diameter of M meters and
elevated at H meters above ground level. The windmill is expected to be
propelled by an average horizontal wind velocity of K kilometers per hour
acting perpendicular to the vertical wheel.

a. Derive a formula expressing the power available from the windmill, in

kilowatts, under the following conditions.

1. Overall efficiency of windmill = 30% 2, Air density = 1.29 kg/m

3. The mass of air horizontally losses, upon contact with the wind wheel,
all its horizontal velocity.

For this purpose, express power in Kw, as function of CO M; and X where: C

- constant (indicate value) inclusive of overall efficiency

M = diameter of windmill, meters

K = average wind velocity, kph

b. Under the preceding conditions, calculate the power available in Kw

from the windmill with a 4-meter wind wheel and propelled by a 30-kph
wind.'

2. A piggery project with 59000-sow capacity established a biogas plant for

the purpose of controlling air pollution and to produce gas for fuel.
Analysis of the gas produced from manure indicated an average
composition by volume of 70% methane (M ) and 30% carbon dioxide 4
(CO 2 ) and traces of other gases with stationary gasoline engines for
various applications by replacing the standard carburetor with a
device which meters the correct proportion of air-mixed biogas.

a. Calculate the air-biogas ratio by volume and by weight required for

complete combustion. Assume air is 21% oxygen and 79X nitrogen, and
biogas is 70% methane by volume. The atomic weights of relevant
elements are shown as follows:

Element Atomic Weight

C 12
0 16
N 14
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b.One of the engines utilized in the fare is a 30-kw gasoline engine

equipped with a forced circulation cooling iystem. To avoid
overheating, the standard radiator is removed, with the water
inlet and outlet tubes of the engine block connected to pipes leading
to a 200-liter open drum filled with water.

If the cooling water pump has an average capacity of 1 liter per

second and one-third of the energy available from combustion is
absorbed by the coolant, calculate the minimum temperature drop in
degree-K, required to maintain_ operating teffiperature. (The specific
heat capacity of water is 4190 Pkg-K and the heat value of methane is
51,000 U/kg)

3. While testing a newly overhauled 4-cylinder, 4-stroke cycle tractor

engine, it was observed that the exhaust valves open 40 late with
respect to the manufacturer's specifications. The valve clearances were
noted to be at the recommended gap but the timing gears were incorrectly
meshed.

a. If the camshaft gear. has 36 teeth, how should the crankshaft gear be
shifted with respect to its direction of rotation and by how many
teeth should the crankshaft gear be adjusted with respect to its
original position in the crankshaft gear"

b. After correcting valve timing, determine the time in seconds that

the exhaust valves of cylinder number one remains open at 'a% engine
speed of 2000 rpm. Assume the exhaust valve opens at 50
before bottom dead center and closes at 1150 after top dead center.

4. In view of the limited time available to complete land preparation and

to ensure timeliness of planting, the manager of a 300-ha corn
plantation decided perform plowing, harrowing and furrowing in a
single field operation. To accomplish these operations
simultaneously,trailing implement consisting of five-bottom disk
plow, an offset disk harrow and six-row furrower will be attached, in
series to a 160 kw four-wheel drive tractor. Each implement will be
equipped with a remote control hydraulic cylinder having a 20.32 cm
length of stroke and a bore diameter of 7.62 cm. Rod diameter is 2.54
cm.

a. Calculate the total power in Kw utilized by the tractor hydraulic pump

in operating all the remote control cylinders connected in series.
Assume &hydraulic PUMP output of 45 li/min, an overall hydraulic system
efficiency of 70%, and the following cylinder thrusts:

Cylinder Thrust
Cylinder A (plow) 18 M
Cylinder B (harrow) 14 M
Cylinder C (furrower) 6 M

b. Determine the required hydraulic pump capacity in liters per second, to

achieve a cylinder rod linear velocity of 12 cm/sec in cylinder A.

c. Calculate the linear velocity in cm/sec of the cylinder rods

NOTE: You will not be given any extra answer sheet or test questions to
replace your dirty answer sheet or test questions'. It is your concern to
make your examination papers clean and neat.

INSTRUCTIONS:

1. Answer the following questions and problems briefly.

2. All solutions and formulas should be presented in the metric system.

PART I - FARM MECHANIZATION, FARM POWER, FARM MACHINERY AND EQUIPMENT (72%)

(12%) 1. In a field demonstration of a rice reaper with a 1.2 m cutter bar,

the following performance data were recorded:
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Average speed of travel 3 kph

Average width of cutter bar
actually utilized 1.0 M
Time lost:
Crossing of dikes 5 min/ha
Repair of broken belt ----- 10 min/ha

Turning and other idle travel

at the end of paddies 10 % o+ effective operating time

Removing field obstructions

and clogging 15 min/ha

From the preceding data, compute:

a. Field efficiency in %.

b. Effective field capacity in hectares per hour.

(18%) 2. A newly purchased grain drill to be used for upland rice

production to be calibrated to determine appropriate operating
speed and seeding rate. The drill has 10 furrow openers spaced 25
cm apart and is equipped with pneumatic tires. When grain hopper
is filled at half its capacity and the tires are inflated at
recommended pressure, the loaded radius is measured at 38 cm.

a. If the wheels are turned at the rate of 60 rpm, what-is the

equivalent ground speed of the machine, in kph, assuming an
average wheel slippage of 15 %?

b. Calculate the -area covered by the drill, in ha. if the wheels were
turned 600 times.

c. After turning the wheels at 60 rpm for a period of 10 minutes, 13.4

kg of palay were collected from the seed tubes. What is the
seeding rate of the drill in cavans per hectare, under the given
conditions? Assume a cavan of palay weighs 44 kg.

(6%)3. A 1000-liter tank for distributing liquid fertilizer is to be

fabricated. Two options were presented for consideration: Tank
A will.have a length of 200 em, width of 150 em and a height of
34 em; Tank B will have a length of 150 em, width of 100 em and
a height of 67 em.

The tank will be mounted on rubber tires each that the bottom will be
65 em above ground. The discharge orifices will be gravity-fed and
located 15 em below ground level.

Which tank will have a lower variation in discharge rate during

field operation (from full tank to practically empty)? Show
calculations to prove your choice.

(6 %) 4. In an attempt to reduce fuel cost, the operator of a fleet of

tractors tried to blend sunflower oil with diesel fuel. Laboratory
tests showed the following properties of two blends:

Fuel Property Sunflower J1/Diesel Fuel Blend

25/75 50/550
(1) Gross heating value
KJ/liter 37,577 37,604
(2) Cetane rating 49.2 51.7
(3) Flash point,0C 73.8 76.7
(4) Cloud point, 0C 18.0 -15.0
(5) Pour point, 0C - 21.0 - 18.0

Explain the meaning of each of the 5 properties indicated and

state in each case which blend -appears to possess better physical
characteristics.

(18%) 5. A tractor engine running at 1200 rpm transmits an inpit torque

of 272 No to the tractor gear train with the following speed
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reductions: transmission, 01; differential, 01; and final

drive, 01. The tractor is equipped with pneumatic drive tires
indicating a static loaded radius of 61 cm, Assuming an overall
power transmission efficiency of 96% and an average wheel
slippage of 15 X, calculate the following:

a. Forward speed availability from the tractor, in kph.

b. Crankshaft-rear axle speed ratio.

c. Output torque available at the drive wheels in Nm.

(12%) 6. Excerpts of specifications and test data of a four-stroke-cycle

diesel tractor are indicated on the following table:

Cylinders --------------------------- 4
Compression ratio - - - - - - - - - - 16.01
Clearance volume per cylinder 7 - - - 71.781 cc:
Flywheel: diameter - - - - - - - - - 40 cm
rim speed at 2100 rpm - - 47,040 cm/min
Rated engine speed - - - - - - - - - 2100 rpm
Maximum torque at 1400 rpm - - - - - 305.1 Nm

From the, given data, calculate the following:

a. Size of engine bore and stroke, in mm.

b. Brakepower, in kW, at 1400 rpm.

c. Brake mean effective pressure, in kPa, at 1400 rpm.

NOTE: You will not be given any extra answer sheet or test questions to
replace your dirty answer sheet or test questions. It is your
concern to make your examination papers clean and neat.

INSTRUCTIONS:

1. Answer the following questions and problems briefly.

2. All solutions and formula should be presented in the metric
system. ANSWER DIRECTLY ON THE SPACE PROVIDED AFTER EACH ITEM.

(5%) 1. Name or describe the strokes in a 4-cycle internal combustion

engine, in the correct order of occurrence.

(10%) 2a. An engine rated at 2000 rpm (revolutions per minute) will be
used to-operate a thresher which has to run at 600 rpm. If the
engine's pulley should be installed on the main drive shaft of
the thresher?

2b. If the thresher has a cleaning fan that should run at 800 rpm
and will be driven by the main drive shaft of the thresher,
recommend the appropriate drive and driven pulley diameters.

(10%) 3a.Describe Position Control and Draft Control in a farm tractor

hydraulic implement hitch system.

3b. Explain."weigh.1 transfer" in a farm tractor hitch !system and

how it improves field efficiency. If necessary, make a schematic
drawing of the tractor and implement and indicate the concept
with arrows.*

(8%) 4a. A farmer uses a carabao and a moldboard plow with a width of cut
of 13 cm to till his rice fields. If he overlaps each pass of
the plow by twenty percent (20%), how many kilometers does lie
have to walk behind the carabao to plow one hectare? (Hint:
Solve by dimensional analysis.)

4b. if his average walking speed in the flooded field is 3 kph. how
long will it take him to plod one hectare (without resting)?
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(6%) 5a. For agricultural applications, give three advantages of diesel

engines over gasoline engines.

5b. 6ive three disadvantages of diesel engines as compared to

gasoline engines:

(6%) 6a. Define the following:

Brake horsepower -

PTO horsepower -

Drawbar horsepower -

Drawbar pull -

6b. A tractor's engine is rated at 80 horsepower. Convert this to the

metric system (kW).

6c. Name two (2) international testing centers for farm tractors which
are universally recognized.

(15%) 7. A farmer borrows P100,000 from a bank to purchase sonic farm

machinery. the loan is payable in five (5) equal principal
payments at sixteen percent (16%) interest per annum on the
diminishing balance (of the principal). Make an amortization
schedule (Table) giving the payment the farmer has to shell out
each year, the interest, the interest portion of the principal
after each payment.

(20%) 8. A contract worker in Saudi Arabia sent his father in Pangasinan

P40,000 to purchase a hand tractor which he could rent out to his
neighbors as a business. Estimate how much the father should
charge for the services of the tractor per pass per hectare using
the following assumptions:

Implement width of cut M - 60 cm

Working speed (s) - 3 kph
Field Efficiency (FE) - 60 %
Fuel consumption - 1.6 liters/hr
Fuel cost - P6.50/liter
Labor cost (2 operators) - P100/day
Usage per year - 90 days
Expected life - 5 years
Depreciation method - straight line
Salvage value - 10 %
Repairs and maintenance - 5 % of original cost/year

Desired return on investment - 24 % (of tractor cost/year)

(20%) 10. A Rotary Club wants to help a cooperative embark on an oyster

mushroom growing project as, a source of funding for its credit
union and day care center. they plan to build three (3) grow out
houses measuring 3 x 6 meters with nipa roof, styrofoam sidings
and volcanic cinder flooring for P * 10,000 each. Each house has
a
capacity of 2,500 spawn bags which they will purchase at PS each.
Mushroom is harvested eAry ten days. the spawn bags have
an
economic life of three (3) months and yield at least 300 grams
each, for the production cycle. Four croppings a year is
projected. the farm gate price of mushroom is P50 per kilo. the
coop plans to apply for a loan with TOC. of P90,000 payable
quarterly for three years at 18% interest per annum. Prepare
a
feasibility study for the project if the houses are depreciated
over 5 years (no.salvage value) and the labor cost is P2m700
a
month. (For simplicity, disregard all other colt items such
as
insurance, taxes, etc.)
 11

5%) 9. In your own words, defend farm mechanization against the labor
displacement issue.

When can farm mechanization be considered appropriate?

(10%)10. It is commonly accepted fact that the core one adds fertilizer
to a commercial crop, the more yield he gets. Describe the
point, G diminishing returns.

NOTE: You will not be given any extra answer sheet nor test questions to
replace your dirty- copies. It is your concern to make your
examination papers clean and neat.

INSTRUCTIONS:

1. Answer the following questions and problems briefly.

2. All solutions and formulas should be presented in the metric system.
3. In multiple choice questions, encircle the letter corresponding to
the correct or most appropriate answer.

TEST 1 - 20%

MULTIPLE CHOICE.Encircle the letter of the correct or most appropriate

answer to the following questions:

1. Factor of Safety" in engineering science refers to:

a. The excess amount of material designed into a machine to ensure

that it does not break down.
b. The ratio of the ultimate strength of a material or component
to the working stress it is expected to be subjected to.
c. The safety of workers in a factory.

2. Automatic Draft Control in a modern farm tractor:

a. Automatically controls the amount of air passing through the

radiator to regulate the operating temperature of the engine.
b. Positions the implement at a constant height or depth relative
to the tractor.
c. Is the hydraulic implement hitch system which automatically
raises or lowers a soil engaging implement to maintain its
draft at a pre-selected value.

3. A dynamometer is used to:

a. Measure electrical consumption.

b. Measure horsepower.
c. Determine dynamic forces.

4. "Side Draft" of a farm tractor and implement system refers to:

a. Wind blowing through the side of the tractor

b. The side slip experienced by the tractor operator as he drives"
across a sloping field.
c. The sideward force acting on a soil-engaging implement like a
plow.

5. "Compression Ratio& refers to

a. The weight of the tractor tires acting on the soil which

results in soil compaction.

b. The - ratio of the cylinder volume when the piston is at the

bottom of its stroke (BD0 to the cylinder volume when it reaches
the top of its stroke (TDC)
c. The device used +pr inflating tractor tires.

6. Torque is:

a. A twistinq or rotating force.

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b. a tool used for tightening cylinder head bolts.

c. A farm animal.

7. "Farm Gate Price" is

a. The price of inputs such as seeds, fertilizers and pesticides

delivered at the farm site.
b. The price of gates for farm fences.
c. The price of raw produce at the +arm level.

8. A Kilowatt (kW) is equivalent to:

a. 1.34 HP
b. 0.45 HP
c. 0.75 HP

9. Mastic Demand" means

a. That when the price of a product decreases, purchases of that

product increases but at a proportionally lower rate.
b. That when the price of a product decreases, sales of that product
increases at a much greater rate.
c. The demand for raw rubber.

10. Compound Interest means

a. Interest yarned on a deposit or debt balance earns interest for

the succeeding periods until withdrawn or paid.
b. Interest computed by a compound geometric formula.
C. Interest earned on an amount of money deposited +or a fixed period
of time in a prime bank.

TEST IL- 5%

Personal computers (PCs) or microcomputers are now in fairly common

usage. Name at least (3) Application Programs which can be most useful to
an Agricultural Engineer in the practice of his profession. (Avoid citing
brand names).
TEST 111 - 5 %

Enumerate the various mechanical field operations undertaken in

growing a crop of corn in their proper sequence. (Note: use back of this
page if necessary).

TEST IV - 5
Which has a smaller rolling resistance: a large diameter tire or a
small diameter tire? Explain why it is so.
TEST V 10

Enumerate the steps a farm machinery supervisor should make in order

to calibrate a tractor mounted, power take-off (PTO) driven boom sprayer.
TEST VI 10 %

A diesel engine that operates at 2,500 rpm will be used to drive an

irrigation pump which should turn at 1,000 rpm. Specify the belt. pulley
diameters required for the engine and the pump.

TEST VII -- 5

If a trader buys play from the farmers at P2.00 a kilo and sells it
to the rice miller at P3.00, what is his percentage mark-up?

His percentage margin (on the selling price)?

TEST VIII -- 10 %

In a 200 hectare corn project, the fields have to be tilled in 30

days. what size heavy duty offset disk harrow (also called locally a plow
harrow) should be selected if the tractor to be used operates at,5 kph.
Assume a 75 % Field Efficiency and an 8 hour working day.

TEST IX.-. 25
 13

A farmer has an opportunity to purchase a reconditioned tractor '

with a heavy offset disk harrow for P300, 000. A rural bank is willing to
finance 80 percent of its cost payable in five (5) equal yearly instalments
at 18 % interest per annum. Determine his expected annual Net Cash Flow
(after debt service but before depreciation charges) using the following
computations.

Tractor power - 59.7 kW

Implement width - '41 m
Working Speed - 6 kph
Working hours per day 8
Field Efficiency - 7S
Number of working days per year - 100
Fuel consumption -- 70 liters/8 hrs
Fuel cost - P6.00 per liter
Repairs and Maintenance -- 7 % of Equipment Cost/year
Custom plowing charges P400/hectare
Wages - 10 % of gross income

If a field is covered with 10 inches of ash, how many cubic meters

per hectare of this ash has to be scraped away or plowed in?

5% 7. Why is contour plowing recommended on sloping land?

If a hard pan prevents rain water from seeping into the soil. easily,
what implement can be used to break this pan?

15% 8. Fill in the equivalent values

1 cubic kilometre= ___________________________ cubic meters

1 KW = ______________W=___________HP

1 bar = ___________psi 1 kg = _______ pounds

1 hectare = _________________ sq. m.= _______ acres

1 km/hr= _________ m/hr. ________ mph

1 seter=___________ inches

10% 9. A hand tractor has a fifty (50) centimeter wide rotary tiller.
Compute its Effective Field Capacity (EF0 if its speed is 5 kph
and Field Efficiency (FE) is 75 percent.

20% Pedro is considering investing his savings in a tricycle business

in his hometown. A brand new unit costs P40,000. The motorcycle
dealer requires a 25 percent downpayment while the balance is
payable in 36 equal tenthly installments at 30 percent interest
per
annum. Make a five (5) year annual cash flow table if Pedro
charges a P75 a day "boundary" or rental, 25 days a month. He
estimates that Repairs and Maintenance (R&M) will amount, to 7
percent of the tricycle's original*cost per year. Registration is
P240 a year. (For simplicity, disregard depreciation and other
charges or costs).
TEST X - 5 %

Name at least five (5) roles or projects wherein Agricultural engineers.,

can be employed in the Comprehensive Agrarian Reform Program (CARP) of the
government.

NOTE: You will not be given any extra answer sheet or test questions to
replace your dirty answer sheet or test questions. It is your concern
to make your examination papers clean and neat.

INSTRUCTIONS:
 14

1.Answer the following questions and problems briefly.

2.All solutions and formulas should be presented in the metric
3.In multiple choice questions, encircle the letter corresponding to
the correct or most appropriate answer.

(20%) I. Encircle the letter of the correct or most appropriate answer to

the following questions: (Note: 2% each)

1. When an agricultural engineer calibrates a sprayer, he

a. measures the diameter of the sprayer tank.
b. cleans the nozzle.
c. measures and adjusts its.application rate

2. In trade circles, CIF stands for

a. Cash In Fist
b. Cost, Insurance and Freight of good to destination port
c. Cost of goods and shipment or departure paint

3. If a farm tractor is rated at 80 horsepower, its metric

equivalent rating is
a. 60 kW
b. 107, kW
c. 75 kW

4. Headland is

a. the strip of land at the ends of a field used for turning of

field machinery.
b. a piece of land owned and tilled by the head of the family.
c. land at the top of a hill.

5. Weight transfer means

a. to move palay from the field to the granary.

b. to transfer the torrens title from the landlord to the tenant.
c. to shift the implement's weight to the tractor's drive wheels
in order to improve traction.

6. In the Philippines, rice is usually transplanted.

a. for weed control reasons as the seedlings have a headstart

over the weeds.
b. to give employment to landless firm workers.
c. to prevent the birds and rats from eating the seeds.

7. Rice is considered to have an inelastic demand. This means that

a. sales increases as its price goes down.

b. consumption hardly changes as its price fluctuates.
c. it does not bounce when dropped from a height of one meter.

8. Prime rate is

a. the cost of top quality bee+.

b. the lowest interest rate that bank charge their good or prime
clients
c. the fuel delivery rate of a diesel engine at its highest power
output.

9. In computer jargon, a high level language is

a. that which is fast and complicated.

b. a language which is easily understood by humans.
c. a language directly understood or read by computers.

10. A Universal Joint is

a. a connector which can-be used on all brands of tractors.

b. used to transmit power between two intersecting shafts,
usually where the angle between them is variable.
 15

c. a prohibited drug used universally.

(5%) II. Name three means by which power is commonly transmitted an farm
machines.

(5%) III. Explain why diesel engines are preferred in large farm tractors
and irrigation pumps.

(5%) IV. Name various mechanical field operations done in growing sugarcane
in their proper order.

(5%) V. If a trader wants to have a margin of thirty (30) percent on his

selling price how much should he mark-up his cost of goods'.'

(10%)VI. A tractor pulls a 2 m wide heavy duty offset disc harrow at an,
operating speed of 6 kph. What is its Theoretical Field Capacity
MO?

Why can this not be obtained under actual field situations? (Cite
factors causing inefficiencies).

(10%)VII. Explain why the drive wheels of a standard four wheel farm
tractor have a large diameter.

If you see tractor tire marks of a soft field with the "arrows''
or lug marks pointing south, which way did the tractor go
(assuming that the tires are mounted correctly)?

Explain why tires should be installed in such a direction.

1

(10%)VIII. Cite reasons why a corn farmer has to plow and harrow his fields
before planting his crops.

Some agricultural engineers and agronomists advocate "zero" or

minimum tillage. What is usually employed to control weeds under
this system? What are it advantages and disadvantages'..)

(5%)IX. A balikbayan brought home a power sander as a gift to his

relatives who have a small woodworking factory in the province. As
the voltages in the U.S. and in his hometown are different, he did
not buy the matching motor thinking he could get a an appropriate
one locally. The sander came with 2.5 in. and 4 in. pulley. The
motor he was able to buy in the local hardware store runs at 3200
rpm. When installed, the sander run much faster than the 1000 rpm
speed recommended in its owner's manual. What should he do?

(25%) X. A farmers cooperative is planning to purchase a tractor with a

"plow-harrow" (generic name: heavy duty trailing offset disc
harrow) to service its members. How much will its tillage cost per
hectare by using the following assumptions?

Equipment Cost - V 700,000.00 Loan terms: 30 % downpayment,

balance payable in 5 equal annual installments at 18 % pa.

Usage 200 days a yr, 8 hr/day

Implement Width - 2.5 m
Operating Speed - 6 kph
Field Efficiency - 70
Fuel Consumption - 60 li/day @ V 5.00/li
Repair and Maintenance (R&M) - 5% of Equipment Cost/yr.
Insurance - 3% of Equipment Cost/yr
Interest Cost (on Coop's equity) - 12 % pa
Housing Cost - nil
 16

NOTE: You will not be given any extra answer sheet or test questions to
replace your dirty answer sheet or test questions. It is your. concern to make
your examination papers clean and neat.

INSTRUCTIONS:

1. Answer the following questions and problems briefly.

2. All solutions and formulas should be presented in the metric

system. ANSWER DIRECTLY ON THE SPACE PROVIDED AFTER EACH ITEM,
EXCEPT FOR MULTIPLE CHOICE WHERE YOU MUST ENCIRCLE THE NUMBER OF
THE CORRECT OR MOST APPROPRIATE ANSWER.

20% 1. Encircle the number of the correct or most appropriate answer: (2% each
item)

a. In trade circles, L/C means

i. Loan Cooperative
ii. Letter of Credit
iii. Low Cash Position

b. Ad Valorem Tariff is based on

i. Quantity or Volume of the product

ii. Value of the product
iii. The Tariff Code

c. Draft Control in farm equipment is

i. The device that adjusts the amount of air that goes through
the radiator.
ii. The harness that is put an a work animal.
iii. The hydraulic implement hitch system which adjusts implement
depth based on a preset draft or resistance value.

d. Safety Factor is

i. The ratio of ultimate strength to working stress.

ii. A seat belt worn by the driver so he is not thrown out.
iii. Savings in the bank.

e. Torque is

i. A farm animal
ii. A twisting force
iii. Lugging power of a diesel engine

f. The approximate number of corn kernels per kilo is

i. 500 to 700
ii. 3,000 to 4,000
iii. 10,000 plus

g. A tractor tire would have lower rolling resistance if

 17

i. It has a lower tire pressure.

ii. It is wider.
iii. It has a larger diameter.

h. In 1 four stroke, single cylinder engine, the power stroke occurs

every

i. Four revolutions of the flywheel

ii. One revolution of the flywheel
iii. Two revolutions of the flywheel.

i. Scouring in a moldboard plow means

i. The plow surface is rusted

ii. The soil slides freely over the surface of the plow bottom
iii. The soil is acidic thus not suitable to till

j. Diesel engines are preferred over gasoline engines for most

agricultural applications because

i. They consume less of a cheaper fuel.

ii. They are cheaper than gasoline engines..
iii. They are lighter.

5% 2. Cite at least three (3) reasons why farmers plow and harrow their
fields before planting a crop.

52 3. Determine the dimensions of a 5,000 liter water tank which has a

diameter of not more than 1.5 meters and a height that does not
exceed 2.5 meters.

5% 4. Why do rice farmers in the Philippines and other Asian countries..

transplant rice seedlings instead of direct seeding them?

10%5. Juan bought a motorcycle on installment. Its list price was P30,000.
He had to give a downpayment of 25% and had to pay P1,258 monthly +or
24 months. What was the effective interest charged Juan?

5% 6. What is AMTEC and what are its objectives?

10% 7. Give the following conversion factors:

1 KW = _____________________ W = _________________ HP

1 bar = _______________ psi

1 hectare = _____________ sq.m. = ________________acres

1 km/hr = ____________________ sq.m. = ___________mph

1 Liter = __________________ cu.m. = _____________gallons

10% 8. Describe the following:

 18

a.Universal Joint –

b. Position Control –

c. Weight Transfer -

10% 9. That are the advantages And disadvantages of using hydraulic systems
for transmitting power in farm tractors, implements and other
agricultural equipment?

20% 10. A Rotary Club wants to help a cooperative embark on an oyster

mushroom growing project as a source of funding for its credit union
and day care center. They plan to build three (3) grow out houses
measuring 3 x 6 meters with nipa roof, styrofoam sidings and volcanic
cinder flooring for P10,000 each. Each house has a capacity of 2,500
spawn bags which they will purchase at PS each. Mushroom is harvested
every ten days. the spawn bags have an economic life of three (3)
months and yield at least 300 grams each for the production cycle.
+our croppings a year is projected. the farm gate price S mushroom is
P50 per kilo. The coop plans to apply for a loan with TLRC of
P90,0000 payable quarterly for three years at 18% interest per annum.
Prepare a feasibility study for the project if the houses are
depreciated over 5 years (no salvage value) and the labor cost is
P2,700 a month. (For simplicity, disregard all other cost items such
as insurance, taxes, etc.)

NOTE: You will hot be given any extra answer sheet or lest questions to
replace your dirty answer sheet or test questions. It is your. concern to make
your examination papers clean and neat.

INSTRUCTIONS:

1. Answer the following questions and problems briefly.,

2. All solutions and formulas should be presented in the metric system.

ANSWER DIRECTLY ON THE SPACE PROVIDED AFTER EACH ITEM, EXCEPT' FOR
MULTIPLE CHOICE WHERE YOU MUST ENCIRCLE THE NUMBER OF THE CORRECT OR
MOST APPROPRIATE ANSWER.

20% 1. Encircle the number of the correct or most appropriate answer: (2%
for each item)

a. In farm machinery terminology, position control refers to

i. The steering wheel of 1 tractor

ii. The implement hitch control lever of the tractor.
iii. The hydraulic hitch system which acts the implement height

constant relative to the tractor chassis.

b. In the banking industry, prime rate

means
 19

i. The yield of large money market placements

ii. The lowest interest rate charged favored bank clients
iii. The price of choice cuts of beef

c. In computer jargon, RAM means

i. A computer virus which destroys its memory

ii. The computer's temporary storage of data which is termed Random
Access Memory.
iii. Reform the Armed Forces Movement.

d. In soil science, friable means

i. The condition of the soil which makes it ideal for plowing and
making of a good seedbed.
ii. A soil with a high clay content which makes it ideal for making
pots.
iii. Nothing.

e. A dead furrow is

i. A butchered pig
ii. The edge of a plowed field.
iii. A canal produced when soil is plowed away from the furrow on both
sides.

f. Brake horsepower is

i. The maximum power measured at the flywheel of an engine without

accessories.
ii. The power of a tractor to pull a plow.
iii. The power needed to stop the tractor.

g. A tractor is rated at 80 hp. In the metric system, this is equivalent to

i. 90 KW
ii. 40 KW
iii. 60 KW

h. Book value of an asset is

i. Its depreciated value as reflected in the company"s books at the time

of appraisal.
ii. Its acquisition cost.
iii. Its salvage value at the end of the depreciation period.

i. Cash Flow is

i. The total cash received from the sale of the farm's products.
ii. The cash that is left in the cash register at the end of the day.
iii. Income less expenses plus depreciation allowance.

j. In farm equipment, PTO stands for

i. Pay to Own.
 20

ii. Push the Obstruction

iii. Power Take-Off.

5% 2 Define Agricultural Engineering.

Name five (5) fields or institutions where an Agricultural Engineer may be

employed in the Philippines.

5% 3. An engine rated at 2000 rpm has to run a water pump at 1000 rpm. If the*
engine has a 4 inch diameter pulley, determine the appropriate pump
pulley if a 5 percent slippage is expected.

10% 4.Describe Draft Control in a farm tractor hydraulic implement hitch

system.

Explain Weight transfer in a tractor-implement system.

5% 5. Explain why water is put into the drive wheels of tractors used or)
dryland operations.

5% 6. What farm implements can be used to take away ash fall from fields in
Central Luzon to make them arable again?