Threaded Joints Multiple Choice Questions – Machine Design

1. Threaded joints are non-separable joints.

a) True
b) False

Answer: b

2. Which type of joints is better when the product is subjected to large vibrations: welded or threaded?

a) Welded
b) Threaded
c) Both have same results
d) Depends on the magnitude of the vibrational force

Answer: a

3. If a fastener is threaded into a tapped hole, then the fastener is likely to be called as

a) Screw
b) Bolt
c) Washer
d) Screw or bolt

Answer: a

4. In nut and bolt fastener, nut is generally held stationary while bolt is rotated.

a) True
b) False

Answer: b

5. Which of the following is not a function of washer?

a) Distributes load over a large area of clamped parts
b) Provides bearing surface over large clearance bolts
c) Prevents marring of the bolt head and nut surface
d) Helps in locking of the fastener

Answer: d

6. Shank is the portion of bolt between the head and the thread.

a) True
b) False

Answer: a

7. If there is no place to accommodate the nut, then one would choose the

a) Through Bolts
b) Tap Bolts
c) Studs
d) None of the mentioned

Answer: b

8. Which of the following are good for parts that are seldom dismantled.

a) Through Bolts
b) Tap Bolts
c) Studs
d) Cannot be stated

Answer: b

9. Which of the following requires more space for the rotation of spanner?

a) Square Head
b) Hexagonal Head
c) Both require equal space of rotation
d) Cannot be stated

Answer: a

10. Fillister, button, flat and hexagonal heads are all tightened externally.

a) True
b) False

Answer: b

11. Set screws are subjected to tensile forces only.

a) Yes
b) No, they are subjected to compressive forces only
c) Both compressive and tensile
d) Can’t be determined

Answer: b

12. If the lateral force acting on the set screw is large and tends to displace one part with respect to other than which point is recommended?

a) Dog Point
b) Cone Point
c) Window Point
d) Cut Point

Answer: a

13. Find the torque required to raise the load of 15kN and mean diameter of triple threaded screw being 46mm. Also given pitch=8mm and coefficient of friction is 0.15.

a) 11831.06N-mm
b) 11813.06N-mm
c) 12811.06N-mm
d) None of the listed

Answer: a

14. What is the collar friction torque if outer and inner diameters are 100mm and 65mm respectively. The coefficient of friction is 0.15 and the load acting is of 15kN. Consider uniform wear theory.

a) 89886.6N-mm
b) 38796.5N-mm
c) 92812.5N-mm
d) 87645.5N-mm

Answer: c

15. For a double threaded screw, what will be the tangent of helix angle if nominal diameter and pitch are 100mm and 12mm respectively?

a) 0.045
b) 0.081
c) 0.094
d) 0.023

Answer: b

16. If for a trapezoidal thread, angle of thread is 15’ then what will be the replacement of the coefficient of friction which is 0.15.

a) 0.1553
b) 0.1335
c) 0.1667
d) 0.1776

Answer: a

5. What will be efficiency of the screw in case of raising the load when coefficient of friction is 0.1553 and tangent of helix angle is 0.0813?

a) 34%
b) 45%
c) 54%
d) 43%

Answer: a

17. A machine vice whose length of the handle is 150mm and the coefficient of friction for thread and collar are 0.15 and 0.17 respectively has a force applied at handle of 125N. Also the outer and inner diameters of collar are 55mm and 45mm respectively. Find the screw torque in terms of clamping force W if nominal diameter=22mm and pitch=5mm.

a) 3.567W N-mm
b) 2.286W N-mm
c) 3.564W N-mm
d) None of the mentioned

Answer: b

18. A machine vice whose length of the handle is 150mm and the coefficient of friction for thread and collar are 0.15 and 0.17 respectively has a force applied at handle of 125N. Also the outer and inner diameters of collar are 55mm and 45mm respectively. Find the collar torque in terms of clamping force W assuming uniform wear theory if nominal diameter=22mm and pitch=5mm.

a) 4.5W
b) 5.4W
c) 4.25W
d) 3.37W

Answer: c

19. A machine vice whose length of the handle is 150mm and the coefficient of friction for thread and collar are 0.15 and 0.17 respectively has a force applied at handle of 125N. Also the outer and inner diameters of collar are 55mm and 45mm respectively. Find the clamping force W if nominal diameter=22mm and pitch=5mm.

a) 4539.45N
b) 2868.73N
c) 3657.56N
d) 2134.34N

Answer: b

20. A machine vice whose length of the handle is 150mm and the coefficient of friction for thread and collar are 0.15 and 0.17 respectively has a force applied at handle of 125N. Also the outer and inner diameters of collar are 55mm and 45mm respectively. Find the overall efficiency if nominal diameter=22mm and pitch=5mm.

a) 18.12%
b) 12.18%
c) 21.23%
d) 23.21%

Answer: b

21. Find the bending stress to which a screw of nominal diameter 22mm is subjected when the clamp exerts a force of 5kN acts on it. The screw is double threaded and pitch of screw is 5mm. Given: The coefficient of friction is 0.15. It is assumed operator exerts a force of 250N at the handle of length 275mm.

a) 123.45N/mm²
b) 132.54N/mm²
c) 142.54N/mm²
d) 124.45N/mm²

Answer: c

22. Find the torsional shear stress to which a screw of nominal diameter 22mm is subjected when the clamp exerts a force of 5kN on it. The screw is double threaded and pitch of screw is 5mm. Given: The coefficient of friction is 0.15.

a) 25.45N/mm²
b) 21.29N/mm²
c) 31.21N/mm²
d) 35.65N/mm²

Answer: b

23. If bending stress in a screw is of magnitude 95N/mm² and torsional shear stress of magnitude 15N/mm², then what is the principal shear stress?

a) 48.7N/mm²
b) 54.3 N/mm²
c) 51.4 N/mm²
d) 49.8 N/mm²

Answer: d

24. The nominal diameter of the screw is 22mm and the allowable bearing pressure for the nut is 15N//mm². Find the length of the nut if pitch of the screw is

a) 15mm
b) 20mm
c) 25mm
d) 30mm

Answer: a

25. A but joint can be defined as a joint between two components lying approximately in a different plane.

a) True
b) False

Answer: b

26. A fillet weld is an approximately triangular cross-section joining two surfaces lying parallel to each other.

a) True
b) False

Answer: b

27. How many types of jacks are there which can be used in a screw jack?

a) 2
b) 3
c) 4
d) 5

Answer: a

28. Which of the following does not form the important part of the screw jack?

a) Frame
b) Nut
c) Cup
d) Coupling

Answer: d

29. The transverse shear stress at the root of the threads in the nut can be given by?(symbols have their usual meaning, z=number of threads in nut)

a) 4W/πdz²
b) W/πdtz
c) 4W/πtd²
d) None of the mentioned

Answer: b

30. What type of friction in cup design is recommended for the set screw?

a) Sliding
b) Rolling
c) Static
d) None of the mentioned

Answer: b

31. A differential screw is defined as a mechanical device consisting of two screws connected in parallel.

a) True
b) False

Answer: b

32. In a differential screw, two screws are connected in series such that the resultant motion is the summation of the motion of the two screws.

a) True
b) False

Answer: b

33. A compound screw consist of two screws in parallel such that the resultant motion is the summation of the individual motion of screws.

a) True
b) False

Answer: b

34. What is the output from differential screws when pitch of the two screws is 12mm and 8mm? Also the nut is rotated by applying a force of 120N at a radius of 300mm and the two screws remain stationary. The torque of raising and lowering for the two screws is 5k N-mm and 2.5k N-mm where k is the effective axial weight on the screw.

a) 13200 N-mm
b) 15200 N-mm
c) 19200 N-mm
d) 17200 N-mm

Answer: c

35. What is the efficiency of differential screws when pitch of the two screws is 12mm and 8mm? The nut is rotated by applying a force of 120N at a radius of 300mm and the two screws remain stationary. The torque of raising and lowering for the two screws is 5k N-mm and 2.5k N-mm where k is the effective axial weight on the screw.

a) 6.48%
b) 8.48%
c) 23.1%
d) 42.8%

Answer: b

36. Efficiency of conventional power screw is greater than the efficiency of recirculating ball screws.

a) True
b) False

Answer: b

37. In which case is the wear more?

a) Conventional power screw
b) Recirculating power screw
c) Equal in both the cases
d) Cannot be determined

Answer: a

38. Resilience is defined as the property of material to absorb energy when deformed _________ and to release this energy when unloaded.

a) Elastically
b) Plastically
c) Up to fracture point
d) None of the listed

Answer: a

40. The shock absorbing capacity of bolt can be increased by making the shank diameter ________ the root diameter.

a) Lesser than
b) Equal to
c) Greater than
d) No effect

Answer: b

41. The shock absorbing capacity of bolts can be increased by

a) Increasing the shank diameter
b) Decreasing the length of shank portion of bolt
c) Increase the shank diameter and decreasing the length of shank
d) None of the listed

Answer: d

42. If the length of the shank is doubled, then strain energy absorbed by shank

a) Doubles
b) Remains same
c) Increases 4 time
d) Become half

Answer: a

43. Which of the following help in accomplishing the locking?

a) Creating supplementary friction
b) Using special locking devices like split pins
c) By plastic deformation
d) All of the listed

Answer: d

44. Crests and roots of the threads may lead to leakage in fluid tight threads if flattened or rounded to a circular arc.

a) True
b) False

Answer: b

45. The static load carrying capacity of fine threads is greater than that of coarse threads.

a) True
b) False

Answer: b

46. Coarse threads have helix angle _____ fine threads.

a) Equal to
b) Greater than
c) Lesser than
d) There is no relation

Answer: c

47. Which threads have greater resistance to unscrewing?

a) Coarse
b) Fine
c) They have equal resistance
d) Cannot be determined

Answer: b

48. Which type of threads is recommended for fluctuating loads?

a) Fine threads
b) Coarse Threads
c) Either of fine or coarse
d) None of the listed

Answer: a

49. If core diameter of bolt is 13.8cm the it’s nominal diameter is given by?

a) 17.27mm
b) 15.34mm
c) 14.67mm
d) 16.34mm

Answer: a

50. In the following figure, two plates are fastened by means of two bolts. The yield strength of bolt is 400N/mm² and factor of safety is 4. Determine the permissible shear stress in the bolts.

a) 100N/mm²
b) 50N/mm²
c) 25N/mm²
d) 75N/mm²

Answer: b

51. In the following figure, two plates are fastened by means of two bolts. The yield strength of bolt is 400N/mm² and factor of safety is 4. Determine the size of the bolts.
a) 8mm
b) 9mm
c) 10mm
d) 11mm

Answer: a

52. The structure shown is subjected to an eccentric force P=5kN and eccentricity=500mm. The horizontal distance between two bolts is 200mm and vertical distance between bolts is 150mm. The yield strength of bolts is 400N/mm² and factor of safety is 3. Determine the primary shear force from the following figure.

a) 625N
b) 1250N
c) 2500N
d) 1000N

Answer: b

53. The structure shown is subjected to an eccentric force P=5kN and eccentricity=500mm. The horizontal distance between two bolts is 200mm and vertical distance between bolts is 150mm. The yield strength of bolts is 400N/mm² and factor of safety is 3. Determine the secondary shear force in the below figure.

a) 2000N
b) 2500N
c) 1500N
d) 5000N

Answer: d

54. The structure shown is subjected to an eccentric force P=5kN and eccentricity=500mm. The horizontal distance between two bolts is 200mm and vertical distance between bolts is 150mm. The yield strength of bolts is 400N/mm² and factor of safety is 3. Determine the resultant shear force on the bolt lying left and above the CG.

a) 4068.58N
b) 4168.58N
c) 5068.58N
d) 5168.65N

Answer: a

55. The structure shown is subjected to an eccentric force P=5kN and eccentricity=500mm. The horizontal distance between two bolts is 200mm and vertical distance between bolts is 150mm. The yield strength of bolts is 400N/mm² and factor of safety is 3. Determine the resultant shear force on the bolt lying right and above the CG.

a) 654334N
b) 6047.44N
c) 5047.44N
d) 5989.32N

Answer: b

56. The structure shown is subjected to an eccentric force P=5kN and eccentricity=500mm. The horizontal distance between two bolts is 200mm and vertical distance between bolts is 150mm. The yield strength of bolts is 400N/mm² and factor of safety is 3. Determine the size of the bolts.

a) 10.74mm
b) 9.23mm
c) 11.54mm
d) 8.68mm

Answer: a9. Which bolt is under maximum shear stress in the following figure?

a) 1
b) 2
c) 3
d) All are under equivalent shear stress

Answer: c

57. Arrange the bolts in order of decreasing shear stresses.

a) 1>2>3
b) 2>1>3
c) 3>1>2
d) 3>2>1

Answer: d

58. Determine the primary shear stress to which the bolts are subjected if P=3kN.

a) 3000N
b) 1000N
c) 2000N
d) None of the listed

Answer: b

59. Determine the secondary shear stress acting on the bolt 3 and its direction. The bolts are equidistant having separated by 60mm and the margin to the left and right is 25mm. Also P=5kN acts at a distance of 200mm from the channel.

a) 6100N vertically up
b) 4500N vertically down
c) 6100N vertically up
d) 4500N vertically down

Answer: c

60. Determine the size of the bolts if yield strength of bolt is 400N/mm² and factor of safety is 4. The bolts are equidistant having separated by 60mm and the margin to the left and right is 25mm. Also P=5kN acts at a distance of 200mm from the channel.

a) 14.34mm
b) 13.44mm
c) 15.44mm
d) 12.66mm

Answer: b

61. Given data for bracket is P=20kN, e=100mm, S(yt)=400N/mm², FS=3. Find the direct shear stress in bolts if diameter=18mm.

a) 16.9N/mm²
b) 19.6 N/mm²
c) 78.6 N/mm²
d) 76.8 N/mm²

Answer: b

62. Given data for bracket is P=20kN, e=100mm, S(yt)=400N/mm², FS=3. If distance between the bolts from the axis of tilting is 125mm and 25mm, then find the effective tensile force acting on the bolts lying at 125mm from tilting axis.

a) 6765.2N
b) 8798.2N
c) 7692.3N
d) 7962.11N

Answer: c

63. Given data for bracket is P=20kN, e=100mm, S(yt)=400N/mm², FS=3. If distance between the bolts from the axis of tilting is 125mm and 25mm, then find the effective tensile force acting on the bolts lying at 25mm from tilting axis.

a) None of the listed
b) 7692.3N
c) 2345.2N
d) 1538.46N

Answer: d

64. Given data for bracket is P=20kN, e=100mm, S(yt)=400N/mm², FS=3. Which bolt can be used as criteria for designing?

a) Left top bolt
b) Both top bolts
c) Left bottom bolt
d) Both bottom bolt

Answer: b

65. Given data for bracket is P=20kN, e=100mm, S(yt)=400N/mm², FS=3. Find the principal shear stress in the top bolts in terms of area A?

a) None of the listed
b) 5309.2/A
c) 6308.2/A
d) 6980.4/A

Answer: c

66. Given data for bracket is P=20kN, e=100mm, S(yt)=400N/mm², FS=3. Find the size of the bolt using maximum shear stress theory.

a) 11mm
b) 12mm
c) 13mm
d) 14mm

Answer: a

67. Given data for bracket is P=20kN, e=100mm, S(yt)=400N/mm², FS=3. Find the size of the bolt using maximum principal stress theory.

a) None of the listed
b) 19.2mm
c) 15.3mm
d) 21.2mm

Answer: b

68. A wall bracket is attached to the wall by means of 2 identical bolts, one at A and one at B. The force of 20kN acts at a distance of 400mm. Bolt A lies at a distance of 50mm from axis of tilt and bolt B 500mm. Allowable shear stress in the bolts is 100N/mm² and tensile is 40N/mm². Which bolt is used a criterion for designing?

a) A
b) B
c) A or B
d) None of the listed

Answer: b

69. A wall bracket is attached to the wall by means of 2 identical bolts, one at A and one at B. The force of 20kN acts at a distance of 400mm. Bolt A lies at a distance of 50mm from axis of tilt and bolt B 500mm. Allowable shear stress in the bolts is 100N/mm² and tensile is 40N/mm². Find the effective tensile force acting in the two bolts.

a) Bolt B=792.07N & Bolt A=792.07N
b) Bolt B=792.07N & Bolt A=7920.8N
c) Bolt B=7920.8N & Bolt A= 792.07N
d) Bolt B=7920.8N & Bolt A=7920.8N

Answer: c

70. A wall bracket is attached to the wall by means of 2 identical bolts, one at A and one at B. The force of 20kN acts at a distance of 400mm. Bolt A lies at a distance of 50mm from axis of tilt and bolt B 500mm. Allowable shear stress in the bolts is 100N/mm² and tensile is 40N/mm². Find the radius of Mohr circle which can be made from the shear stress and tensile stress acting on bolts.(Consider bolt under max stress and area of bolt is A)

a) 10000/A N/mm²
b) 6378.5/A N/mm²
c) 10755.7/A N/mm²
d) None of the listed

Answer: b

71. A wall bracket is attached to the wall by means of 2 identical bolts, one at A and one at B. The force of 20kN acts at a distance of 400mm. Bolt A lies at a distance of 50mm from axis of tilt and bolt B 500mm. Allowable shear stress in the bolts is 100N/mm² and tensile is 40N/mm². Find the ratio of the effective tensile load to which the two bolts are subjected.

a) 1
b) 10
c) 12
d) 8

Answer: b

72. A wall bracket is attached to the wall by means of 2 identical bolts, one at A and one at B. The force of 20kN acts at a distance of 400mm. Bolt A lies at a distance of 50mm from axis of tilt and bolt B 500mm. Allowable shear stress in the bolts is 100N/mm² and tensile is 40N/mm². Determine the size of bolts using maximum shear stress theory.

a) 12mm
b) 9mm
c) 16mm
d) 18mm

Answer: b

73. A wall bracket is attached to the wall by means of 2 identical bolts, one at A and one at B. The force of 20kN acts at a distance of 400mm. Bolt A lies at a distance of 50mm from axis of tilt and bolt B 500mm. Allowable shear stress in the bolts is 100N/mm² and tensile is 40N/mm². Determine the size of bolts using maximum principal stress theory.

a) 16.1mm
b) 22.2mm
c) 20.2mm
d) 18.1mm

Answer: d

74. A flange of radius 200mm is fastened to the machine screw by means of four cap screws of pitch circle radius 150mm. The external force P is 20kN which is loaded at 160mm from the machine screw. There are two dowel pins to take shear load. Determine the maximum effective tensile force acting on the bolt. The four bolts are equally spaced radially.

a) 4777.6N
b) 5777.6N
c) 6777.6N
d) 7777.7N

Answer: a

75. A flange of radius 200mm is fastened to the machine screw by means of four cap screws of pitch circle radius 150mm. The external force P is 20kN which is loaded at 160mm from the machine screw. There are two dowel pins to take shear load. Determine the core diameter of cap screw if permissible tensile stress in cap screw is 40N/mm².

a) None of the listed
b) 11.21mm
c) 12.33mm
d) 14.12mm

Answer: c

76. A round flange bearing is fastened to the machine frame by means of 4 cap screws. The angle made by central axis of bolt 2 and horizontal is θ. Also the radii of flange and pitch circle are a & b respectively. Given: Sum of squares of distance of bolts from axis of tilt is 2a² +b². Are all the four bolts under equal effective tensile load?

a) Yes
b) No
c) Depends on magnitude of load
d) Cannot be stated

Answer: b

77. A round flange bearing is fastened to the machine frame by means of 4 cap screws. The angle made by central axis of bolt 2 and horizontal is θ. Also the radii of flange and pitch circle are a & b respectively. Given: Sum of squares of distance of bolts from axis of tilt is 2a² +b². Determine the angle θ so that the force in the bolt 1 has maximum value.

a) 180’
b) 90’
c) 0’
d) 45’

Answer: a

78. A round flange bearing is fastened to the machine frame by means of 4 cap screws. The angle made by central axis of bolt 2 and horizontal is θ. Also the radii of flange and pitch circle are a & b respectively. Given: Sum of squares of distance of bolts from axis of tilt is 2a² +b². Which bolt is under maximum stress if dowel pins are used to relieve cap screws from shear stress?

a) 1
b) 2
c) 3
d) 4

Answer: c

79. Which of the following statements are true about eccentrically loaded circular base?

a) All bolts are symmetrically spaced with equal angle on either side of vertical
b) Bolts are not preloaded
c) Bearing is rigid
d) Dowel pins are used to relieve stresses

Answer: a

80. Certain types of radial bearings can also take thrust load.
a) True
b) False

Answer: a

81. Balls and the races of the deep groove ball may roll freely without any sliding.

a) True
b) False

Answer: a

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