Elements of Machine Design-07

Design of shafts, keys and couplings

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1 If shaft diameter is 60mm, how many bolts are recommended for rigid flange coupling?

(A) 2

(B) 3

(D) 6

[showhide type=”button7c1″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

2 Determine the diameter of the bolts used in rigid flange coupling if transmitted torque is 270N-m, pitch circle diameter=125mm and four bolts are emplace in the coupling. Permissible shear stress in the bolts is 70N/mm².

(A) 3.8mm

(B) 3.6mm

(D) 4mm

[showhide type=”button7c2″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

3 The hub is treated as a solid shaft while calculating torsional shear stress in the hub.

(A) TRUE

(B) FALSE

[showhide type=”button7c3″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

4 Find the shear stress in a flange at the junction of hub in rigid flanged coupling if torsional moment is 2980N-m and diameter of hub being 125mm. Also the thickness of flange is 25mm.

(A) 6.77N/mm²

(B) 10.24N/mm²

(D) 4.22N/mm²

[showhide type=”button7c4″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

5 Which property is not required for shaft materials?

(A) High shear and tensile strength

(B) Good machinability

(D) Good cast ability

[showhide type=”button7c5″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

6 When a solid shaft is subjected to torsion, the shear stress —– induced in the shaft at its center is

(A) Minimum

(B) Zero

(D) Average

[showhide type=”button7c6″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

7 The design of shafts made of brittle materials is based on

(A) Guest’s theory

(B) Rankine’s theory

(D) Von Mises theory

[showhide type=”button7c7″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

8 When a shaft is subjected to a twisting moment, every cross section of the shaft will be under

(A) Tensile stress

(B) Compressive stress

(D) Bending stress

[showhide type=”button7c8″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

9 The product of the tangential force acting on the shaft and its distance from the axis of the shaft (i.e., the radius of the shaft) is known as

(A) Bending moment

(B) Twisting moment

(D) Flexural rigidity

[showhide type=”button7c9″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

10 A sunk key fits in the keyway of the —– only.

(A) Hub

(B) Sleeve

(D) Neither hub nor sleeve

[showhide type=”button7c10″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

11 Hollow saddle key is superior to flat saddle key as far as power transmitting capability is concerned.

(A) TRUE

(B) FALSE

[showhide type=”button7c11″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

12 The main advantage of sunk key is that it is a —– drive.

(A) Positive

(B) Negative

(D) None of the listed

[showhide type=”button7c12″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

13 Woodruff key permits —– movement b/w shaft and the hub.

(A) Axial

(B) Radial

(D) None of the listed

[showhide type=”button7c13″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

14 Determine the length of Kennedy key required to transmit 1200N-m and allowable shear in the key is 40N/mm². The diameter of shaft and width of key can be taken as 40mm and 10mm respectively.

(A) 49mm

(B) 36mm

(D) 53mm

[showhide type=”button7c14″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

15 A universal coupling used to connect two shafts

(A) Which are not in exact alignment

(B) Which are perfectly aligned

(D) Have lateral misalignment

[showhide type=”button7c15″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

16 A flange coupling is used to connect two shafts

(A) Which are perfectly aligned

(B) Which are not in exact alignment

(D) Whose axes intersect at a small

[showhide type=”button7c16″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

17 The taper on key is given on

(A) Bottom side only

(B) Top side only

(D) Any side

[showhide type=”button7c17″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

18 Which of the following statement is wrong?

(A) A key is used as a temporary fastening

(B) A key is subjected to tensile stresses

(D) A key prevents relative motion between the shaft and boss of the pulley

[showhide type=”button7c18″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

19 In designing a key, it is assumed that the distribution of forces along the length of the key

(A) Varies linearly

(B) Is uniform throughout

(D) Varies exponentially, being less at the torque-input end

[showhide type=”button7c19″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

20 The taper on a rectangular sunk key is

(A) 1 in 16

(B) 1 in 32

(D) 1 in 100

[showhide type=”button7c20″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

21 The type of stresses developed in the key is/are

(A) Shear stress alone

(B) Bearing stress alone

(D) Shearing, bearing and bending stresses

[showhide type=”button7c21″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

22 A saddle key ———- power through frictional resistance only

(A) Transmits

(B) Does not transmit

[showhide type=”button7c22″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

23 The thickness of key is usually taken equal to one-sixth of diameter of shaft.

(A) Yes

(B) No

[showhide type=”button7c23″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

24 Does a keyway slot in shaft reduce the strength of shaft?

(A) Yes

(B) No

[showhide type=”button7c24″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

25 A tapered key which fits in a key way in the hub and if flat on the shaft, is known as

(A) Feather key

(B) Gib-head key

(D) Flat saddle key

[showhide type=”button7c25″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

26 When the pulley or other mating piece is required to slide along the shaft, a ———- sunk key is used.

(A) Rectangular

(B) Square

[showhide type=”button7c26″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

27 —- is used to transmit the torque between the shaft and the adjoining machine part like gear, pulley or sprocket.

(A) Bearing

(B) Key

(D) Any of the above

[showhide type=”button7c27″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

28 Key used when the key is to be removed frequently.

(A) Sunk Key

(B) Feather Key

(D) Gib Head Key

[showhide type=”button7c28″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

29 Most common key used for industrial purposes.

(A) Rectangular key

(B) Square sunk key

(D) Spline key

[showhide type=”button7c29″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

30 Best use case for round key

(A) High power transmission

(B) Low power transmission

[showhide type=”button7c30″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

31 Following are the main types of couplings.

(A) Rigid

(B) Flexible

(D) None of the above

[showhide type=”button8c1″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

32 Which of the following elements is used to connect two shafts?

(A) Clutch

(B) Brakes

(D) None of the above

[showhide type=”button8c2″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

33 A muff coupling is.

(A) Rigid coupling

(B) Flexible coupling

(D) None of the above

[showhide type=”button8c3″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

34 A bushed-pin type flange coupling is used.

(A) For intersecting shafts

(B) When the shafts are not in exact alignment

(D) For parallel shafts

[showhide type=”button8c4″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

35 A universal coupling is used to connect two shafts.

(A) Which are not in exact alignment

(B) Which are perfectly aligned

(D) Have lateral misalignment

[showhide type=”button8c5″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

36 A flange coupling is used to connect two shafts.

(A) Which are perfectly aligned

(B) Which are not in exact alignment

(D) Whose axes intersect at a small angle

[showhide type=”button8c6″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

37 The sleeve or muff coupling is designed as a.

(A) Dun cylinder

(B) Hollow shaft

(D) Thick cylinder

[showhide type=”button8c7″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

38 A Flange Coupling Is.

(A) Used for non-collinear shafts

(B) Used for collinear shafts

(D) Used only on small shafts rotating at slow speeds

[showhide type=”button8c8″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

39 Actual stress in the bolts of a flanged coupling of a shaft will be.

(A) More than the designed strength

(B) Less than the designed strength

(D) None

[showhide type=”button8c9″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

40 The flanges of a flange coupling are coupled together by means of bolts and their number depends upon.

(A) Length of the shaft

(B) Material of the shaft

(D) Rotational speed of the shaft

[showhide type=”button8c10″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

41 Which types of coupling used to connect shafts, whose axis are parallel but not in one line?

(A) Muff coupling

(B) Flexible coupling

(D) Flange coupling

[showhide type=”button8c11″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

42 Universal coupling is used to connect two shafts

(A) Which are perfectly aligned

(B) Which are not in exact alignment

(D) Whose axes intersect at a small angle

[showhide type=”button8c12″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

43 The universal coupling is a type of ————

(A) Flexible coupling

(B) Rigid coupling

(D) None of the above

[showhide type=”button8c13″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

44 Which of the following coupling is used to connect two shafts which have both lateral and angular misalignment?

(A) Bush pin type coupling

(B) Universal coupling

(D) All of these

[showhide type=”button8c14″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

45 Which of the following is rigid coupling?

(A) Muff coupling

(B) Split muff coupling

(D) All of the above

[showhide type=”button8c15″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

46 Which Coupling is modification of Flange coupling?

(A) Bush Pin type

(B) Oldham

(D) Muff

[showhide type=”button8c16″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

47 The Coupling Bolts are known as

(A) Muff

(B) Nuts

(D) All of above

[showhide type=”button8c17″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

48 What are the types of Flange Coupling?

(A) Protected

(B) Unprotected

(D) All of the above

[showhide type=”button8c18″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

49 Which of the following is not type of flexible Coupling?

(A) Oldham Coupling

(B) Universal Coupling

(D) Bushed pin type

[showhide type=”button8c19″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

50 Which Coupling is simpler in design?

(A) Muff or Sleeve

(B) Flange

(D) All above

[showhide type=”button8c20″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

51 Muff Coupling consist of a hollow cylinder called as

(A) Shaft

(B) Muff

(D) Both B and C

[showhide type=”button8c21″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

52 Magnitude of shear stress induced in a shaft due to applied torque varies from

(A) Maximum at centre to zero at circumference

(B) Maximum at centre to minimum (not-zero) at circumference

(D) Minimum (not zero) at centre to maximum at circumference

[showhide type=”button8c22″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

53 The variation of shear stress in a circular shaft subjected to torsion is

(A) Linear

(B) Parabolic

(D) Uniform

[showhide type=”button8c23″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

54 The relation governing the torsional torque in circular shafts is

(A) T/r=τ/l=Gθ/J

(B) T/J=τ/r=Gθ/l

(D) T/l=τ/r=Gθ/J

[showhide type=”button8c24″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

55 Torsional rigidity of a shaft is defined as

(A) G/J

(B) GJ

(D) T/J

[showhide type=”button8c25″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

56 Torsional rigidity of a shaft is given by

(A) Gl/θ

(B) Tθ

(D) T/l

[showhide type=”button8c26″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

57 A solid shaft of same cross sectional area and of same material as that of a hollow shaft can resist

(A) Less torque

(B) More torque.

(D) Unequal torque

[showhide type=”button8c27″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

58 Angle of twist of a circular shaft is given by

(A) GJ/Tl

(B) Tl/GJ

(D) TG/Jl

[showhide type=”button8c28″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

59 Maximum shear stress of a solid shaft is given by

(A) 16T/πd

(B) 16T/πd2

(D) 16T/πd4

[showhide type=”button8c29″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

60 The ratio of maximum bending stress to maximum shear stress on the cross section when a shaft is simultaneously subjected to a torque T and bending moment M,

(A) T/M

(B) M/T

(D) 2M/T

[showhide type=”button8c30″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

61 Maximum shear stress in a hollow shaft subjected to a torsional moment is at the

(A) Middle of thickness

(B) At the inner surface of the shaft

(D) At the middle surface of the shaft

[showhide type=”button9c1″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

62 The ratio of strength of a hollow shaft to that of a solid shaft subjected to torsion if both are of the same material and of the same outer diameters, the inner diameter of hollow shaft being half of the outer diameter is

(A) 15/16

(B) 16/15

(D) 8/7

[showhide type=”button9c2″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

63 Ratio of diameters of two shafts joined in series is 2. If the two shafts have the same Material and the same length the ratio of their angles of twist is

(A) 2

(B) 4

(D) 16

[showhide type=”button9c3″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

64 Ratio of diameters of two shafts joined in series is 2. If the two shafts have the same material and the same length the ratio of their shear stresses is

(A) 2

(B) 4

(D) 16

[showhide type=”button9c4″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

65 For two shafts joined in series, the ————— in each shaft is same.

(A) Shear stress

(B) Angle of twist

(D) Torsional stress

[showhide type=”button9c5″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: C [/showhide]

66 For two shafts joined in parallel, the ————— in each shaft is same.

(A) Shear stress

(B) Angle of twist

(D) Torsional stress

[showhide type=”button9c6″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: B [/showhide]

67 The shafts are NOT made of

(A) Mild steel

(B) Alloy steel

(D) Cast iron

[showhide type=”button9c7″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: D [/showhide]

68 The shafts are designed on the basis of

(A) Strength and rigidity

(B) Ductility

(D) Resilience

[showhide type=”button9c8″ more_text=”Show Answer” less_text=”Hide Answer”] Answer: Option: A [/showhide]

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