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Indian Forest Service I Examination ........
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....... ..... • •..• J I D-VSF-L-ZRA I
MECHANICAL ENGINEERING
Paper I
I Time Allowed Three Hours! jMaximum Marks: 200!
INSTRUCTIONS
Candidates should attempt Questions No. l and
5 which are compulsory, and any THREE of the
remaining questions, selecting at least ONE
question from each Section .
•
All questions carry equid mark.s.
Marks carried by parts of a question are
indicated against each.
Answers must be written in ENGLISH only.
If any data is considered insufficient, assume
suitable values and indicate the same clearly.
Unless otherwise indicated, symbols and
notations have their usual meanings.
SECTION A
1.Attempt any four of the following
(a)Discuss how single cylinder 4-stroke
reciprocating engine is balanced. 10

circular rod has 5 cm diameter for a length of
0·6m, 8cm diameter for a length of 1·8m and
3cm diameter for a length of 0·25m. A disc of
mass moment of inertia 15 kg m2 is suspended
with the help of this rod such that the disc is in
horizontal plane. Neglecting inertia effect of the
rod, find natural frequency of torsional
oscillation in Hz. Assume G 0·8 x 10 power11 Pa. 10
(c)Compare the bending strengths of three beams
of same material, same weight and same depth
if one of them has solid rectangular area of
6 x 20 cm2. The second beam is a hollow
rectangular section having a wall thickness of
2cm. The third beam has I-section of equal
flanges having web and flange thickness equal to
2cm. 10
(d)The load on a rod consists of an axial pull of
10 kN along with a transverse shear force of
5kN. Determine the diameter of the rod by using
the following theories of failure
(i)Strain energy theory
(ii)Shear strain energy theory
Elastic limit in tension is 270 N/mm 2 and a
factor of safety of 3 is to be used.
Poisson's ratio 0.3. 10
(e)Explain bainite, martensite. Show with a
figure,the variation of hardness of martensite
with %C. Discuss polycarbonate, its properties
and applications. Complete the table below for
surface hardening process. 10
<img src='./qimages/1476-1e.jpg'>

2.(a)The total sleeve movement in a Hartnell type of
governor is 3cm. At mid position of sleeve, the
sleeve arm which is 6cm long, is horizontal. The
length of ball arm is also 6cm. The speed at the
lowest position is 430 rpm. If the spring stiffness
is 50 find the speed in rpm at the top
position of the sleeve. At midspan the ball rotates
at 10cm radius. The mass of the ball is 1·3 kg. 10

epicyclic gear train consists of a sun gear; a
stationary internal gear and three identical
planet gears which are carried on a star-shaped
planet carrier. The sun gear, internal gear and
planet carrier have common axis. The speed of
the planet carrier is one-fifth of the speed of the
sun gear in the same sense. If minimum number
of teeth on any gear is limited to 18, determine
the number of teeth on each gear. Determine the
torque to keep the internal gear stationary, if
input torque at sun gear is 100 Nm. 10
A machine is vibrating with an amplitude of
0·04mm at 500 cpm. An instrument weighing
20 kg is mounted on the four isolators on the
machine. Each isolator has stiffness 314 N/cm
and damping factor" of 392 N sec/m. Determine
(i)amplitude of vibration of instrument, and
(ii)dynamic load on each isolator. 20

3.(a)Two planes AB and AC make an angle of 50deg at
point A. Plane AB is subjected to tensile stress
3 kN/cm2 and shear stress 3 kN/cm2 from B
towards A. Plane AC is subjected to a normal
stress of unknown magnitude and a shear stress
of magnitude 2 kN/cm2 from C towards A.
Determine
(i)normal stress on plane AC, and
(ii)principal stresses. 15

(b)Design a suitable helical spring for a balance
which is used to measure 0 to 100 kg over a scale
of 80 mm. The spring is to be enclosed in a casing
of 25 mm diameter. Approximate number of
turns is 30. Also calculate the maximum shear
stress induced. G 0·85 x 107 N/cm2. 10
A steel sleeve is pressed onto a solid steel shaft
which has 5cm diameter. The radial pressure
between shaft and sleeve is 1800 N/cm2 and
hoop stress at the inner surface of the sleeve is
4500 N/cm2. If an axial compressive load of
50 kN is applied to the shaft, determine change
in radial pressure at the interface of shaft and
sleeve Assume mew 0.3. 15

4.(a)Prove that the packing fraction for F.C.C.
structure is 0·74. Draw the phase diagram of
Pb-Sn alloy and from this diagram draw cooling
curve for eutectic alloy. How many atoms per
mm2 are there on the planes of lead
(Pb radius·= 0·1750 nm) What is deformation
by twinning
(b)Describe the following heat treatment processes
(i)Full annealing
(ii)Process annealing
Mention some advantages of thermosets and
write at least four types of such material. What
are the special properties of PTFE What are the
materials used to make porcelain Write some
important applications of oxide ceramics.

SECTION B
5. Attempt any four of the following
(a)What are the disadvantages of abrasive jet
machining Write some of its applications.
Write the advantages, limitations and
applications of electron beam machining. What
is the safety problem connected with EBM 10
(b)Discuss with figure the various steps required
for friction welding, mentioning at least two
methods of control. What is meant by low
hydrogen electrode What is the maximum
output current that can be drawn at 100% duty
cycle from a welding power source rated at 600
A at 60% duty cycle. 10
NC machine, what is the purpose of the
parity check What is the function of Data
Processing Unit and Control Loop Unit
of MCU. How is Feed Rate Number
expressed What is indirect feedback 10
(d)Prepare a flow diagram for writing the
computer programme in FORTRAN for Pulse
MIG welding process. 10

a four-month period, the best rainfall forecast
is derived by using 40% of the rainfall for the
most recent month; 30% of two months ago; 20%
of three months ago; and 10% of four months ago;
if the actual rainfall was as follows
Month1 Month2 Month3 Month4
100 90 105 95
What is the rainfall forecast for Month 5

6.(a)What are the functions of jig Draw a jig to
machine four holes in a plate. What are two
reasons for not having drill bushings actually
touching the workpiece What is a duplex
fixture
(b)What is meant by interchangeable manufacture
Laser light has unique advantages for inspection.
What are they Define the terms 'roughness
height', 'waviness width' and in connection with surface irregularities. 10

(c)Discuss deep-hole drilling keeping in mind speed
and feed, mentioning the technique of applying
coolant. What is the main difference between rose
reamer and chucking reamer Write in short
about shell reamer. 10
(d)Write four advantages of high velocity forming
process. What advantages does press forming
have over drop forging Why are pure metals
more easily cold worked than alloys Compare
metal spinning with press work. 10

7.(a)National Bank is considering opening a drive-in
window for serving the tourists at a forest entry
gate. Management estimates that tourists will.
arrive for banking service at the rate of 15 per
hour. The teller whom it is considering to staff
the window can service customers at the rate of
one every three minutes. Assuming Poisson
arrivals and exponential service, compute 25
(i)The average utilization of the teller.
(ii)Average number in the waiting line.
(iii)Average number in the system.
(iv)Average waiting time in line.
(v)Average waiting time in the system.
(b)Specify the output and the cost objectives of the
following organizations
Forest Service Regional Office.
Summer Camp for children.
For each of the organizations listed above,
develop an organization chart.

The daily demand for forest product is normally
distributed with a mean of 60 and a standard
deviation of 7. The source of supply is reliable
and maintains a constant lead time of six
days. If the cost of placing the order is rupees10 and
annual holding costs are rupees 0·50 per unit, compute
the order quantity and reorder point to satisfy
95% of the customers. Given that 95%
corresponds to 1·645 standard deviation. 20

(b)The plating process for metal desk equipment
painted by dipping can produce defective parts
either because of too thick or too thin a plating or
because of defective appearance, which shows up
in surface defects. A record of twenty samples
follows construct a suitable control chart and
plot the twenty samples. Is the process in
control
<img src='./qimages/1476-8b.jpg'>