1000+ Machine Design Multiple Choice Question Answer [Solved]

1. The efficiency of a square threaded screw is maximum if the helix angle is equal to (Where ? = Angle of friction)
A. 90° - ?
B. 45° - ?
C. 45° - ?/2
D. 45° + ?/2
Answer : C

2. The flank of the tooth is the
A. Surface of the top of the tooth
B. Surface of the tooth above the pitch surface
C. Width of the tooth measured along the pitch circle
D. Surface of the tooth below the pitch surface
Answer : D

3. Lewis form factor for 14 ½° composite and full depth involute system is (where T = Number of teeth)
A. 0.124 - (0.684/T)
B. 0.154 - (0.912/T)
C. 0.175 - (0.841/T)
D. None of these
Answer : A

4. A chain drive transmits __________ power as compared to belt drive.
A. More
B. Less
C. Same
D. None of these
Answer : A

5. 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. Angular bevel gears
B. Mitre gears
C. Internal bevel gears
D. Crown bevel gears
Answer : D

6. The standard length of the shaft is
A. 6 m
B. 5 m
C. 7 m
D. All of these
Answer : D

7. Fabric belts are used in industrial applications because
A. They are cheap
B. They can work at high temperature
C. They are unaffected by moisture and humidity
D. None of the above
Answer : A

8. Resilience of a material is important, when it is subjected to
A. Combined loading
B. Fatigue
C. Thermal stresses
D. Shock loading
Answer : D

9. Three different weights fall from a certain height under vacuum. They will take
A. Same time to reach earth
B. Times proportional to weight to reach earth
C. Times inversely proportional to weight to reach earth
D. None of the above
Answer : A

10. In a flat belt drive, if the slip between the driver and belt is 1 %, between the belt and follower is 3% and driver and follower pulley diameters are equal, then velocity ratio of the drive will be
A. 0.96
B. 0.97
C. 0.98
D. 0.99
Answer : A

11. When a close coiled helical spring is compressed, its wire is subjected to
A. Tension
B. Shear
C. Compression
D. All of the above
Answer : A

12. In the levers of third type, the mechanical advantage is __________ one.
A. Less than
B. Equal to
C. More than
D. None of these
Answer : A

13. In designing a connecting rod, it is considered like __________ for buckling about X-axis.
A. Both ends hinged
B. Both ends fixed
C. One end fixed and the other end hinged
D. One end fixed and the other end free
Answer : A

14. An imaginary circle which by pure rolling action gives the same motion as the actual gear, is called
A. Addendum circle
B. Dedendum circle
C. Pitch circle
D. Clearance circle
Answer : C

15. 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

16. Belt slip may occur due to
A. Heavy load
B. Loose belt
C. Driving pulley too small
D. All of the above
Answer : D

17. The number of slots in a 25 mm castle nut is
A. 8
B. 4
C. 2
D. 6
Answer : D

18. When carbon in the cast iron is principally in the form of graphite, the cast iron will be of
A. Brown colour
B. Yellow colour
C. White colour
D. Grey colour
Answer : D

19. Which of the following statement is correct?
A. The distance from a point on one thread to the corresponding point on the next thread is called pitch
B. The distance which a screw thread advances axially in one rotation of the nut is called lead
C. In single start threads, lead is equal to pitch
D. All of the above
Answer : D

20. A flange coupling is used to connect two shafts
A. Which are perfectly aligned
B. Which are not in exact alignment
C. Have lateral misalignment
D. Whose axes intersect at a small angle
Answer : A

21. The application of third type levers is found in
A. Handle of a hand pump
B. Hand wheel of a punching press
C. Lever of a loaded safety valve
D. A pair of tongs
Answer : D

22. The dedendum is the radial distance from the
A. Pitch circle to the top of a tooth
B. Pitch circle to the bottom of a tooth
C. Top of a tooth to the bottom of a tooth
D. Addendum circle to the clearance circle
Answer : B

23. In helical gears, the distance between similar faces of adjacent teeth along a helix on the pitch cylinders normal to the teeth, is called
A. Normal pitch
B. Axial pitch
C. Diametral pitch
D. Module
Answer : A

24. The maximum stress due to stress concentration in a bar having circular transverse hole, as compared to its static stress without hole will be
A. Same in both cases
B. 2 times more
C. 3 times more
D. 4 times more
Answer : C

25. The included angle for the V-belt is usually
A. 10°-20°
B. 30°-40°
C. 40°-60°
D. 60°-80°
Answer : B

26. According to I.B.R., when the thickness of boiler shell (t) is greater than 8 mm, then the diameter of rivet hole (d) is obtained by
A. Equating tearing resistance of the plate to the shearing resistance of the rivets
B. Equating tearing resistance of the plate to the crushing resistance of the rivets
C. Equating shearing resistance to the crushing resistance of the rivets
D. None of the above
Answer : B

27. Which of the following property is essential for spring materials?
A. Stiffness
B. Ductility
C. Resilience
D. Plasticity
Answer : C

28. In a full journal bearing, the angle of contact of the bearing with the journal is
A. 120°
B. 180°
C. 270°
D. 360°
Answer : D

29. If the tearing efficiency of a riveted joint is 75%, then the ratio of diameter of rivet to the pitch is equal to
A. 0.2
B. 0.25
C. 0.50
D. 0.6
Answer : B

30. If T is the actual number of teeth on a helical gear and ? is the helix angle for the teeth, then formative number of teeth is written as
A. T sec³?
B. T sec²?
C. T/sec³?
D. T cosec?
Answer : A

31. A column is known as a long column if the slenderness ratio is
A. 40
B. 50
C. 70
D. 100
Answer : D

32. The most important dimension in the design of a nut is
A. Pitch diameter
B. Inside diameter
C. Outside diameter
D. Height
Answer : D

33. In a band and block brake, the ratio of tensions on the tight and slack sides of band is given by (where ? = Coefficient of friction between the blocks and the drum, ? = Semi-angle of each block subtending at the centre of drum, and n = Number of blocks)
A. T?/T? = ?? × n
B. T?/T? = (??)ⁿ
C. T?/T? = [(1 - ? tan?)/ (1 + ? tan?)]ⁿ
D. T?/T? = [(1 + ? tan?)/ (1 - ? tan?)]ⁿ
Answer : D

34. Which of the following statement is wrong?
A. The V-belt may be operated in either direction with tight side of the belt at the top or bottom
B. The V-belt drive is used with large centre distance
C. The power transmitted by V-belts is less than flat belts for the same coefficient of friction, arc of contact and allowable tension in the belts
D. The ratio of driving tensions in V-belt drive is more than flat belt drives
Answer : B

35. A double fillet welded joint with parallel fillet weld of length l and leg s is subjected to a tensile force P. Assuming uniform stress distribution, the shear stress in the weld is given by
A. ?2P/s.l
B. P/2.s.l
C. P/?2.s.l
D. 2P/s.l
Answer : C

36. Lewis equation in gears is used to find the
A. Tensile stress in bending
B. Shear stress
C. Compressive stress in bending
D. Fatigue stress
Answer : C

37. A localised compressive stress at the area of contact between two members is known as
A. Bending stress
B. Shear stress
C. Tensile stress
D. Bearing stress
Answer : D

38. Stress concentration is caused due to
A. Variations in load acting on a member
B. Variations in properties of materials in a member
C. Abrupt change of cross-section
D. All of these
Answer : C

39. The stress which vary from a minimum value to a maximum value of the same nature (i.e. tensile or compressive) is called
A. Repeated stress
B. Yield stress
C. Fluctuating stress
D. Alternating stress
Answer : C

40. The rated life of a bearing varies
A. Directly as load
B. Inversely as square of load
C. Inversely as cube of load
D. Inversely as fourth power of load
Answer : C

41. Which is positive drive?
A. Flat belt drive
B. V-belt drive
C. Crossed belt drive
D. Timing belt
Answer : D

42. In a multiple V-belt drive, if one of the belts break, then
A. Only the broken belt is replaced
B. The entire set of belts is replaced
C. The broken belt and the belt on either side of it, is replaced
D. The broken belt need not to be replaced
Answer : B

43. The tension on the slack side of the belt is __________ the tension on the tight side of the belt.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : B

44. Wire ropes as compared to cotton ropes
A. Are lighter in weight
B. Offer silent operation
C. Can withstand shock loads
D. All of these
Answer : D

45. The piston rod of a steam engine is usually connected to the crosshead by means of
A. Bolted joint
B. Knuckle joint
C. Cotter joint
D. Universal joint
Answer : C

46. The ratio of endurance limit in shear to the endurance limit in flexure is
A. 0.70
B. 0.25
C. 0.40
D. 0.55
Answer : D

47. The crest diameter of a screw thread is same as
A. Major diameter
B. Minor diameter
C. Pitch diameter
D. Core diameter
Answer : A

48. 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

49. A special case of ductility which permits materials to be rolled or hammered into thin sheets, is called
A. Plasticity
B. Elasticity
C. Ductility
D. Malleability
Answer : D

50. Oldham coupling is used to connect two shafts
A. Which are perfectly aligned
B. Which are not in exact alignment
C. Which have lateral misalignment
D. Whose axes intersect at a small angle
Answer : C