1000+ Machine Design MCQ for LIC ADO [Solved]

1. The metal suitable for bearings subjected to heavy loads is
A. White metal
B. Silicon bronze
C. Monel metal
D. Phosphor bronze
Answer : A

2. In designing a sleeve coupling, length of the sleeve is taken as (where d = Diameter of the shaft)
A. d + 17 mm
B. 2d + 13 mm
C. 2d + 20 mm
D. 3.5d
Answer : D

3. The shear stress at a point in a shaft subjected to a torque is
A. Directly proportional to the polar moment of inertia and to the distance of the point from the axis
B. Directly proportional to the applied torque and inversely proportional to the polar moment of inertia
C. Directly proportional to the applied torque and the polar moment of inertia
D. Inversely proportional to the applied torque and the polar moment of inertia
Answer : B

4. In hydrodynamic bearings
A. The oil film pressure is generated only by the rotation of the journal
B. The oil film is maintained by supplying oil under pressure
C. Do not require external supply of lubricant
D. Grease is used for lubrication
Answer : A

5. In levers, leverage is the ratio of
A. Load lifted to the effort applied
B. Mechanical advantage to the velocity ratio
C. Load arm to the effort arm
D. Effort arm to the load arm
Answer : D

6. Tearing resistance required to tear off the plate per pitch length is (where p = Pitch of rivets, d = Dia. of rivet hole, and ?t = Permissible tensile stress for plate material)
A. p.d.?_t
B. p.t.?_t
C. (p - d) ?_t
D. (p - d) t.?_t
Answer : D

7. A transmission shaft includes
A. Over head shaft
B. Counter shaft
C. Line shaft
D. All of these
Answer : D

8. The bending moment M and a torque T is applied on a solid circular shaft. If the maximum bending stress equals to maximum shear stress developed, then M is equal to
A. T/2
B. T
C. 2T
D. 4T
Answer : A

9. When the belt is transmitting maximum power,
A. The tension in tight side is twice the centrifugal tension
B. The tension in slack side is equal to the centrifugal tension
C. The tension in tight side is thrice the centrifugal tension
D. None of the above
Answer : A

10. A locking device extensively used in marine type connecting rod ends is a
A. Jam nut
B. Castle nut
C. Sawn nut
D. Ring nut
Answer : D

11. Which is correct statement? Stress concentration in static loading is
A. Very serious in brittle materials and less serious in ductile materials
B. Very serious in ductile materials and less serious in brittle materials
C. Equally serious in both types of materials
D. Seriousness would depend on other factors
Answer : A

12. The ball bearings are provided with a cage
A. To reduce friction
B. To facilitate slipping of balls
C. To prevent the lubricant from flowing out
D. To maintain the balls at a fixed distance apart
Answer : D

13. According to Indian standards, total numbers of fundamental deviations are
A. 10
B. 15
C. 20
D. 25
Answer : D

14. Crowning on pulley helps
A. In decreasing the slip of the belt
B. In increasing the slip of the belt
C. To keep the belt in centre on a pulley while it is in motion
D. To increase pulley life
Answer : C

15. For general industrial machinery, the ratio of the length of journal to its diameter is taken as
A. 0.5 to 1
B. 1 to 2
C. 3 to 5
D. 5 to 10
Answer : B

16. The maximum shear stress theory is used for
A. Brittle materials
B. Ductile materials
C. Plastic materials
D. Nonferrous materials
Answer : B

17. For applications involving high stresses in one direction only the following type of thread would be best suited
A. ISO metric thread
B. Acme thread
C. Square thread
D. Buttress thread
Answer : D

18. For circumferential joint in boilers, the type of joint used is
A. Butt joint with single cover plate
B. Butt joint with double cover plate
C. Lap joint with one ring overlapping the other
D. Any one of the above
Answer : C

19. If d is the normal diameter of a bolt in mm, then the initial tension in kg in a bolt used for making a fluid tight joint as for steam engine cover joint is calculated by the relation
A. 124 d
B. 138 d
C. 151 d
D. 168 d
Answer : D

20. Gear box is used
A. To produce torque
B. For speed reduction
C. To obtain variable speeds
D. To increase efficiency of system
Answer : C

21. Set screws are
A. Similar to small size tap bolts except that a greater variety of shapes of heads are available
B. Slotted for a screw driver and generally used with a nut
C. Used to prevent relative motion between parts
D. Similar to stud
Answer : C

22. Which of the following statement is correct?
A. A parallel sunk key is a taperless key
B. A parallel sunk key may be rectangular or square in cross-section
C. A flat saddle key is a taper key which fits in a key way of the hub and is flat on the shaft
D. All of the above
Answer : D

23. Which of the following screw thread is used for power transmission in one direction only?
A. Square threads
B. Multiple threads
C. Acme threads
D. Buttress threads
Answer : D

24. If a bearing is designated by the number 305, it means that the bearing is of
A. Medium series whose bore is 5 mm
B. Medium series whose bore is 25 mm
C. Light series whose bore is 25 mm
D. Light series whose bore is 5 mm
Answer : B

25. In a belt drive, if the pulley diameter is doubled keeping the tension and belt width constant, then it will be necessary to
A. Increase the key length
B. Increase the key depth
C. Increase the key width
D. Decrease the key length
Answer : A

26. The rivet head used for boiler plate riveting is usually
A. Pan Head
B. Snap head
C. Counter sunk head
D. Conical head
Answer : B

27. Two closely coiled helical springs with stiffness k? and k? respectively are connected in series. The stiffness of an equivalent spring is given by
A. (k? k?)/ (k? + k?)
B. (k? - k?)/ (k? + k?)
C. (k? + k?)/ (k? k?)
D. (k? - k?)/ (k? k?)
Answer : A

28. The endurance limit in shear of carbon steel can be obtained by multiplying the endurance limit in flexure by a factor of
A. 0.45
B. 0.55
C. 0.65
D. 0.75
Answer : D

29. In a horizontal flat belt drive, it is customary to use
A. Bottom side of belt as slack side
B. Top side of belt as slack side
C. Idler pulley
D. None of the above
Answer : B

30. Two rigid plates are clamped by means of bolt and nut with an initial force F. After tightening, a separating force P (P < F) is applied to the lower plate, which in turn acts on the nut. The tension in the both after this is
A. F + P
B. F P
C. P
D. F
Answer : A

31. A hollow saddle key is
A. A taper key which fits half in the key way of hub and half in the key way of shaft
B. A taper key which fits in a key way of the hub and is flat on the shaft
C. A taper key which fits in a key way of the hub and the bottom of the key is shaped to fit the curved surface of the shaft
D. Provided in pairs at right angles and each key is to withstand torsion in one direction only
Answer : C

32. A bench vice has following type of threads
A. Metric
B. Square
C. Buttress
D. Acme
Answer : D

33. According to I.B.R., the factor of safety of riveted joint should not be less than
A. 1
B. 2
C. 3
D. 4
Answer : D

34. If a shaft made from ductile material is subjected to combined bending and twisting moment, calculations based on which one of the following failure theories will give the most conservative value?
A. Maximum principal stress theory
B. Maximum shear stress theory
C. Maximum strain energy theory
D. Maximum distortion energy theory
Answer : A

35. The strap end of a connecting rod of steam engine is joined by
A. Gib of cotter joint
B. Sleeve and cotter joint
C. Spigot socket cotter joint
D. Knuckle joint
Answer : A

36. The objective of crowning of the flat pulleys of belt drive is to
A. Prevent the belt from running off the pulley
B. Increase the power transmission capacity
C. Increase the belt velocity
D. Prevent the belt joint from damaging the belt surface
Answer : A

37. Split nut is a locking device in which
A. One smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
B. A slot is cut partly in middle of nut and then slot reduced by tightening screw
C. A hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed on the bolt causing a tight grip
D. Through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter pin splitted and bent in reverse direction at the other end
Answer : B

38. In order to ensure self locking in a screw jack, it is essential that helix angle is __________ friction angle.
A. Larger than
B. Smaller than
C. Equal to
D. None of these
Answer : B

39. A screw is said to be over hauling screw, if its efficiency is
A. More than 50 %
B. Less than 50 %
C. Equal to 50 %
D. None of these
Answer : A

40. In V-belt drive, belt touches
A. At bottom
B. At sides only
C. Both at bottom and sides
D. Could touch anywhere
Answer : B

41. The building up of worn and undersized parts, subjected to repeated loads by electroplating is
A. est method
B. Extremely hazardous
C. Has no effect as regards fatigue strength
D. Cheapest method
Answer : A

42. A steel containing 0.8% carbon is known as
A. Eutectoid steel
B. Hypereutectoid steel
C. Hypo-eutectoid steel
D. None of these
Answer : A

43. The coefficient of friction in belt drive depends upon
A. Material of belt
B. Material of pulley
C. Materials of belt and pulley
D. Belt velocity
Answer : C

44. When a hole of diameter d is punched in a metal of thickness 't', then the force required to punch a hole is equal to (where ?u = Ultimate shear strength of the material of the plate)
A. d.t.?_u
B. ?d.t.?_u
C. ?/4 × d².?_u
D. ?/4 × d² × t.?_u
Answer : B

45. When an open coiled helical compression spring is subjected to an axial compressive load, the maximum shear stress induced in the wire is (where D = Mean diameter of the spring coil, d = Diameter of the spring wire, K = Wahl's stress factor, and W = Axial compressive load on the spring)
A. (WD/ ?d³) × K
B. (2WD/ ?d³) × K
C. (4WD/ ?d³) × K
D. (8WD/ ?d³) × K
Answer : D

46. If shearing stress in nut is half the tensile stress in a bolt, then nut length should be equal to
A. Diameter of bolt
B. 0.75 × diameter of bolt
C. 1.25 × diameter of bolt
D. 1.5 × diameter of bolt
Answer : A

47. A self locking screw has
A. Fine threads
B. Course threads
C. Coefficient of friction is greater than tangent of load angle
D. Hole for inserting split pin
Answer : C

48. The usual clearance provided in hydrodynamic bearing per mm of diameter of shaft is
A. 0.01 micron
B. 0.1 micron
C. 1 micron
D. 10 microns
Answer : C

49. The ratio of driving tensions for flat belts, neglecting centrifugal tension, is (where T?, and T? = Tensions on the tight and slack sides of belt respectively, ? = Coefficient of friction, between the belt and pulley, and ? = Angle of contact)
A. T?/T? = ??
B. log (T?/T?) = ??
C. T?/T? =e??
D. T?/T? = log ??
Answer : C

50. Pick up wrong statement. Fatigue strength can be increased by
A. Cold working
B. Shot peening
C. Grinding and lapping surface
D. Hot working
Answer : D