Roll No ....................... .
Total Pages : 4
209604
MAY, 2019
B.Tech. (MECHANICAL ENGINEERING),
6th SEMESTER
Machine Design- II (ME-308-C)
Time : 3 Hours] [Max. Marks : 75
Instructions .·
1. It is compulsory to answer all the questions (1.5 marks
each) of Part-A in short.
2. Answer any four questions from Part-B in detail.
3. Different sub-parts of a question are to be attempted
adjacent to each other.
4. Use of Design Data book is allowed.
PART-A
1. (a) Why pressure angle is generally taken as 20°? (1.5)
(b) How are bearings mounted? (1.5)
(c) Write two functions of a flywheel. (1.5)
(d) What are two most usual cause s of failur es of
crankshaft? (1.5)
(e) What is the effect of surfac e factor on fatigu e
strength ? ( 1.5)
(t) What is the effect of reliability factor on fatigue
strength ? (1.5)
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(g) What is the meaning of various tenns in a screw
4. A screw jack is required to lift a load of 5 kN .The jack has
MlOXl.5? (1.5)
screw with squate treards having two threads per 12 mm
(h) Why square threads are used in screw jack? ( 1.5)
(i) Explain the effect of heat generation in design of length. If the coefficient of friction between nut and screw
gears. ( 1.5) is 0.08 and outer diameter is 60 mm, find the force required
(j) What is the use of C-clamp? ( 1.5) at the end of 600mm long lever to lift the load. Sketch the
screw jack with the dimensions. ( 15)
PART-B
2. Design a helical gear to transmit 30 kW from the following 5. (a) Why dissimilar materials are used for worm and worm
data: wheel? And explain the designation 4n9!10.6n.5l50
Helix angle = 300, used for the pair of worm and worm gear. (5)
Speed of pinion = 1500 rpm, (b) Describe fatigue design for finite and infinite life against
Pressure angle= 200 FOi,
combined variable stresses using Goodman and
Velocity ratio = 4, (10)
Soderberg's Criterion.
No of teeth on pinion = 24,
•
Static stress for CI = 55 N/mm 2, ff
6. (a) Detennine the dimensions of an I-section connecting
BHN for pinion and gear material = 350,
rod for a petrol engine from the following data :
Young's modulus of elasticity for pinion and gear
material= 2.1 x HP N/ mm2 • (15) Diameter of the- piston = 110 ·mm; Mass of the
reciprocating parts = 2 kg; Length of the connecting
3. (a) Explain the Selection of suitable lubricants for rod from centre to centre = 325 mm; Stroke
bearing. (5) length= 150 mm; R.P.M.= 1500 with possible over
(b) A deep groove ball bearing has a rated static and
speed of 2500; Compression ratio = 4 : l; Maximum
dynamic load capacity of 4150 N and 4750 N
explosion pressure = 2.5 N/rnm2• ( l 0)
respectively. The bearing has to take an axial load of
2075 Nanda radial load of 4000 N. Find the expected (b) Describe stepwise procedure for design of the crane
life of the bearing. (10) hook. (5)
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7.
•
(a) A punching machine is driven by 3 KW, 1000
RPM
powered motor with a gear set of 5 : 1 and a stroke
length of 250 mm. Rated capacity of the punching
machine is 22 KN. Consider coeff. of fluctuation of
speed, Cs = 0.02, take 500 mm to be the max size of
the flywheel dia. Calculate the mass moment of inertia
required for the flywheel of the punching press
machine. (10)
(b) Des crib e step wis e pro ced ure for des ign
of the
flywheel. (5)
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