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Total Number of Pages : 02 B.Tech

PAU5I101
5th Semester Regular / Back Examination 2019-20
DESIGN OF MACHINE COMPONENTS
BRANCH : AUTO
Max Marks : 100
Time : 3 Hours
Q.CODE : HRB064
Answer Question No.1 (Part-1) which is compulsory, any EIGHT from Part-II and any TWO
from Part-III.
The figures in the right hand margin indicate marks.

Part- I
Q1 Only Short Answer Type Questions (Answer All-10) (2 x 10)
a) State some applications of Lever in engineering practice.
b) Name the various modes of failure of a fulcrum pin.
c) The body of an airplane is thick cylinder (yes/no). Why?
d) What is the effect of centre distance and pulley size, on the life of a belt?
e) Differentiate between gear and belt drives.
f) What is law of gearing?
g) What is meant by wear load of a gear tooth?
h) What is co-efficient of steadiness?
i) Explain the various stresses induced in the connecting rod.
j) Under what force, the big end bolts and caps are designed?

Part- II
Q2 Only Focused-Short Answer Type Questions- (Answer Any Eight out of Twelve) (6 x 8)
a) A cylindrical pressure vessel of 50 mm diameter is subjected to an internal pressure of
1.5 N/mm2. If the the thickness of the vessel is 15 mm, determine the hoop stress,
longitudinal stress and maximum shear stress.
b) Classify and describe the various types of Levers.
c) A pair of parallel helical gears, consists of an 18 teeth pinion, meshing with a 64 teeth
gear. The normal module is 3 mm. The helix angle is 23°, while the normal pressure
angle is 20°, Calculate the transverse module, transverse pressure angle and axial
pitch.
d) Determine the principal dimensions of a worm gear drive, to transmit 10Kw, with a
worm rotating at 1400 rpm. The velocity ratio is 12 and the tooth form of the gear is 14°
involute. The centre distance is 200mm.
e) A pair of straight bevel gears, consists of a 30 teeth pinion meshing with a 45 teeth
gear. The module and face widths are 5 mm and 35 mm respectively. The pinion as
well as the gear are made of steel with static strength of 200 MPa. Determine the
beam strength of the tooth.
f) A bronze spur pinion rotating at 600 rpm, drives a cast steel gear. The transmission
ratio is 3. The pinion has 20 teeth with 23° full depth involute profile; the module being
5 mm. The face width of the gearing is 25 mm. determine the power that can be
transmitted from the stand point of strength. Static strength for bronze is 80 MPa and
for cast steel it is 100 MPa.
g) Differentiate between the functions of flywheels used for punching machine and I. C
engine.
h) A petrol engine develops 60 kW at a mean speed of 1400rpm. The maximum variation
of energy per revolution is 30% of mean energy. The co-efficient of fluctuation of
speed is 0.02. Determine the necessary mass of the flywheel rim, if the rim provides
95% of the flywheel effect. The mean velocity of the rim is 50m/sec.

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i) A soft cone clutch has a cone pitch angle of 10°, mean diameter of 300 mm and a face
width of 100 mm. If the co-efficient of friction is 0.2 and an average pressure of
0.07N/mm2 for a speed of 500 rpm, find the force required to engage the clutch and
the power.
j) A flywheel of mass 100kg and radius of gyration 350 mm is rotating at 720 rpm. It is
brought to rest by means of a brake. The mass of the brake drum assembly is 5kg.
The brake drum is made of cast iron FG 260 having specific heat 460J/kg°C. Assuming
that the total heat generated is absorbed by the brake drum only, calculate the
temperature rise.
k) A C.I flat pulley transmits 20kW at a speed of 560 rpm. The pulley overhangs the
nearest bearing by 200 mm. Assuming the ratio of belt tensions as 3; Determine
a) shaft diameter b) pulley diameter c) cross-section of eight arms.
l) An overhang crank pin is subjected to a maximum force of 50 kN through the
connecting road. Allowing the bearing pressure of 50MPa and a bending stress of 60
MPa, design the pin.

Part-III
Only Long Answer Type Questions (Answer Any Two out of Four)
Q3 A lever safety valve is 75 mm in diameter, and the blow-off pressure is 1.5 N/ mm2. (16)
The dead weight of the lever is 850 N. The length of the lever is 850 mm and the
distance between the fulcrum of the lever and the valve centre is 85 mm. The
permissible stresses for the material of the lever are : 60, 50 and 80 MPa in tension,
shear and crushing respectively. Allowable bearing pressure in the pin is 20 MPa.
Design the lever.

Q4 A screw jack carries a load of 22 kN. Assuming the coefficient of friction between (16)
screw and nut as 0.15, design the screw and nut. Neglect collar and column friction.
The permissible compressive and shear stresses in the screw should not exceed 42
MPa and 28 MPa respectively. The shear stress in the nut should not exceed 21 MPa,
the bearing pressue in the nut is 14 N/mm2. Also determine the effort required at the
handle of 200 mm length in order to raise and lower the load. What will be the
efficiency of the screw?

Q5 A double start worm has teeth of 6 mm axial module, and its pitch diameter is 50 mm. (16)
if the worm gear has 40 teeth of 20 ° involute tooth profile, and the coefficient of friction
of the worm gearing is 0.015, find
a) The lead angle of the worm
b) Velocity ratio
c) Centre distance
d) Efficiency of the worm gearing

Q6 Design a pair of spur gears with stub teeth and to transmit 50kW, from 180 mm pinion, (16)
running at 2400 rpm to a gear running at 1400 rpm. Both the gears are made of steel
having BHN of 260. Determine the pitch of the gears by means of Lewis equation and
then modify the dimensions if required to keep within the limits set by the dynamic and
wear load requirements.

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