# Design of Machine Elements 9

Mechanical Engineering MCQ Question Papers: DRDO, ISRO, Interview

Subject: Design of Machine Elements 9

Part 3: List for questions and answers of Design of Machine Elements –II

Q1.A cylindrical roller bearing is subjected to frictional torque of 500 N-mm. What is the approximate power loss if the shaft rotates at 1500 r.p.m?
a) 0.0785 kw
b) 0.0392 kw
c) 0.0526 W
d) 0.0236 W

Q2.What is the frictional torque acting on a cylindrical roller bearing of 50 mm diameter which is subjected to radial load of 30 kn and has coefficient of friction 0.0011?
a) 109 kn-mm
b) 900 kn-mm
c) 825 N-mm
d) 1650 N-mm

Q3.What is the effect of large diametric quotient on worm and worm wheel?
a) Strength and rigidity of worm shaft is high
b) Efficiency of worm shaft increases
c) Worm shaft becomes weaker
d) All of the above

Q4.Which of the following relations is true?
(where nw = worm speed, ng = worm gear speed, zg = number of teeth on worm gear, zw = number of starts on worm)
a) Nw α (1/zg)
b) Nw / ng = zg /zw
c) Nw / ng = zw /zp
d) Nw zg = ng zw

Q5.The shortest distance between worm gear and axes of the worm is given as
______________
a) M (zw + zg) / q
b) M (zw + zg) / 2
c) M (q + zg) / 2
d) √m (q + zg) / 2

Q6.A standard worm gear pair is designated as 4/40/10/8, what does number 10 in it indicate?
a) Number of starts on worm
b) Diametral quotient
c) Centre distance
d) Module

Q7.What is the effect of large diametric quotient on worm and worm wheel?
a) Strength and rigidity of worm shaft is high
b) Efficiency of worm shaft increases
c) Worm shaft becomes weaker
d) All of the above

Q8. The sleeve or muff coupling is designed as a
a) Dun cylinder
b) Thick cylinder
c) Solid shaft
d) Hollow shaft

Q9.The ratio of the ultimate stress to the design stress is known as
a) Elastic limit
b) Strain
c) Factor of safety
d) Bulk modulus

Q10.The shortest distance between worm gear and axes of the worm is given as
______________
a) M (zw + zg) / q
b) M (zw + zg) / 2
c) M (q + zg) / 2
d) √m (q + zg) / 2

Q11.A standard worm gear pair is designated as 4/40/10/8, what does number 10 in it indicate?
a) Number of starts on worm
b) Diametral quotient
c) Centre distance
d) Module

Q12.A worm gear pair is designated as 1/30/10/8. What is the face width of the worm gear?
a) 30 mm
b) 53.07 mm
c) 58.4 mm
d) 62.3 mm

Q13.A worm gear pair has 2 starts on worm thread, 11.2 as diametric quotient, 2 as module and 38 numbers of teeth on worm gear. How is the gear pair designated with these specifications?
a) 2/11.2/38/2
b) 11.2/2/38/2
c) 2/38/2/11.2
d) 2/38/11.2/2

Q14What is the shortest distance between worm gear and axes of the worm for a worm gear pair designated as 2/40/10/8?
a) 50 mm
b) 200 mm
c) 320 mm
d) 360 mm

Q15.If pressure angle is 22 deg and coefficient of friction is 0.05. What is the axial force acting on the worm gear designated as 1/40/10/5, if tangential force of 1200 N acts on it?
a) 1241.2 N
b) 2618.4 N
c) 7755.1 N
d) 7847.4 N

Q16.What is the axial force acting on a worm gear for a worm gear pair 1/40/9.5/10, if tangential and axial force of 6213 N and 9236 N act respectively on the worm? ( Φn = 25o & μ = 0.04)
a) 6213 N
b) 9263 N
c) 3050 N
d) Insufficient data

Q17.A chain drive is used for
a) Very short distance
b) Short distance
c) Medium distance
d) Distance is no criteria for such drives

Q18.Screws used for power transmission should have
a) Low efficiency
b) High efficiency
d) Strong teeth

Q19.When bevel gears connect two shafts whose axes intersect at an angle greater than a right angle and one of the bevel gears has a pitch angle of 90°, then they are known as
a) Sngular bevel gears
b) Crown bevel gears
c) Internal bevel gears
d) Mitre gears

Q20.A screw is said to be over hauling screw, if its efficiency is
a) Less than 50%
b) More than 50%
c) Equal to 50%
d) None of these

Part 3: List for questions and answers of Design of Machine Elements –II