Elements of Machine Design-06

  1. Fundamentals of design
  2. Design of joints, levers and offset links
  3. Design of shafts, keys and couplings
  4. Design of power screws
  5. Design of springs
  6. Design of bolted and welded joints
  7. Selection of anti-friction bearings and gears

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1   If T₁ and T₂ are the tensions on the tight and slack sides of the belt respectively, and Tc is the centrifugal tension, then initial tension in the belt is equal to
    (A)   T₁ – T₂ + Tc
    (B)   T₁ + T₂ + Tc
    (C)   (T₁ – T₂ + Tc)/2
    (D)   (T₁ + T₂ + Tc)/2
2   Which of the following is a power transmitting element?
    (A)   Nuts and bolts
    (B)   Sprockets and chains
    (C)   Axles
    (D)   All of the above
3   The shaft directly connected to the power source is called as ______
    (A)   Line shaft
    (B)   Counter shaft
    (C)   Both A and B
    (D)   None of the above
4   Which of the following is a machine shaft?
    (A)   Line shaft
    (B)   Counter shaft
    (C)   Crankshaft
    (D)   All of the above
5   Which of the following statements is/are true?
    (A)   Jaw clutch is a positive clutch
    (B)   The power transmitting capacity of a friction clutch is inversely proportional to the coefficient of friction between contacting surfaces
    (C)   Driving and driven plates in friction clutches are held together due to radial force applied by the helical springs
    (D)   All of the above
6   A flange coupling is used
    (A)   For intersecting shafts
    (B)   For collinear shafts
    (C)   For small shafts rotating at slow speeds
    (D)   For parallel shafts
7   While designing a flange coupling, care is taken so that
    (A)   Shaft is the weakest component
    (B)   Bolts are the weakest component
    (C)   Key is the weakest component
    (D)   The flange is the weakest component
8   A bushed-pin type flange coupling is used
    (A)   For intersecting shafts
    (B)   When the shafts are not in exact alignment
    (C)   For small shafts rotating at slow speeds
    (D)   For parallel shafts
9   A muff coupling is
    (A)   Rigid coupling
    (B)   Flexible coupling
    (C)   Shock absorbing coupling
    (D)   None of the above
10   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
    (C)   Neither more nor less than the designed strength
    (D)   None
11   A stud has
    (A)   Both ends threaded
    (B)   Threads in the mid portion of its length
    (C)   A hole drilled through for inserting locking pin
    (D)   A plane slotted head for the screw driver
12   The shaft length is increased by connecting two or more pieces of suitable lengths by
    (A)   Cotter joint
    (B)   Knuckle joint
    (C)   Bolted joints
    (D)   Keys and couplings
13   Spot the odd one out
    (A)   Muff coupling
    (B)   Flange coupling
    (C)   Split coupling
    (D)   Bushed pin type coupling
14   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
    (C)   Diameter of the shaft
    (D)   Rotational speed of the shaft
15   For a flanged coupling, the diameter of bolts, ‘d’ is worked out from the relation (if ‘D’ is the diameter of the shaft and ‘n’ is the number of bolts)
    (A)   d=0.5D/ √(n)
    (B)   d=0.25D/ √(n)
    (C)   d=0.75D/ √(n)
    (D)   d=1.0D/ √(n)
16   The pin of a bushed pin coupling be checked for
    (A)   Compress stress
    (B)   Maximum principal stress
    (C)   Shear stress
    (D)   Bending stress
17   Identify the machine element given in the figure
    (A)   Muff coupling
    (B)   Oldham coupling
    (C)   Universal of Hooke’s coupling
    (D)   Flanged coupling
18   Identify the machine element given in the figure
    (A)   Muff coupling
    (B)   Oldham coupling
    (C)   Universal of Hooke’s coupling
    (D)   Flanged coupling
19   Identify the machine element given in the figure

    (A)   Muff coupling
    (B)   Oldham coupling
    (C)   Universal of Hooke’s coupling
    (D)   Flanged coupling
20   Identify the machine element given in the figure

    (A)   Muff coupling
    (B)   Oldham coupling
    (C)   Universal of Hooke’s coupling
    (D)   Flanged coupling
21   Oldham coupling is used to connect two shafts having intersecting axes.
    (A)   TRUE
    (B)   FALSE
22   A machine started malfunctioning due to some issues with the coupling. The coupling emplaced in the machine was Oldham. The only coupling available in the workshop is Hooke’s coupling. So, Oldham coupling can be replaced by Hooke’s coupling.
    (A)   TRUE
    (B)   FALSE
23   The coupling used to connect two shafts with large angular misalignment is:
    (A)   Flange coupling
    (B)   Oldham’s coupling
    (C)   Hooke’s joint
    (D)   None of the above
24   In a flange coupling, the keys are staggered at __________ along the circumference of the shafts in order to divide the weakening effect caused by key ways.
    (A)   90°
    (B)   135°
    (C)   160°
    (D)   180°
25   A shaft coupling should
    (A)   Be easy to connect or disconnect
    (B)   Transmit full power of the shaft
    (C)   Hold the shafts in perfect alignment
    (D)   All of these
26   Shaft coupling is used in machinery to
    (A)   Introduce mechanical flexibility
    (B)   Introduce protection against over loads
    (C)   Reduce the transmission of shock loads
    (D)   All of these
27   A tangent key is provided in pairs at right angles and each key is to withstand torsion in one direction only.
    (A)   Agree
    (B)   Disagree
28   A feather key transmits a turning moment and permits axial movement also.
    (A)   TRUE
    (B)   FALSE
29   The thickness of key is usually taken equal to one-sixth of diameter of shaft.
    (A)   Yes
    (B)   No
30   The taper on a rectangular sunk key is
    (A)   1 in 16
    (B)   1 in 32
    (C)   1 in 48
    (D)   1 in 100
31   A key made from a cylindrical disc having segmental cross-section is known as
    (A)   Feather key
    (B)   Gib-head key
    (C)   Wood ruff key
    (D)   Flat saddle key
32   When the pulley or other mating piece is required to slide along the shaft, a __________ sunk key is used.
    (A)   Rectangular
    (B)   Square
    (C)   Parallel
33   The taper on key is given on
    (A)   Bottom side only
    (B)   Top side only
    (C)   On both sides
    (D)   Any side
34   The main advantage of sunk key is that it is a _____ drive.
    (A)   Positive
    (B)   Negative
    (C)   Neutral
    (D)   None of the listed
35   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
36   Which of the following statement is wrong?
    (A)   A key is used as a temporary fastening
    (B)   A key is subjected to tensile stresses
    (C)   A key is always inserted parallel to the axis of the shaft
    (D)   A key prevents relative motion between the shaft and boss of the pulley
37   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
    (C)   Varies exponentially, being more at the torque-input end
    (D)   Varies exponentially, being less at the torque-input end
38   The standard length of the shaft is
    (A)   5 m
    (B)   6 m
    (C)   7 m
    (D)   All of these
39   A key way lowers
    (A)   The strength of the shaft
    (B)   The rigidity of the shaft
    (C)   Both the strength and rigidity of the shaft
    (D)   The ductility of the shaft
40   A tapered key which fits in a key way in the hub and is flat on the shaft, is known as
    (A)   Feather key
    (B)   Gib-head key
    (C)   Wood ruff key
    (D)   Flat saddle key
41   A taper key which fits half in the key way of the hub and half in the key way of shaft, is known as
    (A)   Sunk key
    (B)   Flat saddle key
    (C)   Hollow saddle key
    (D)   Tangent key
42   A feather key is generally
    (A)   Loose in shaft and tight in hub
    (B)   Tight in shaft and loose in hub
    (C)   Tight in both shaft and hub
    (D)   Loose in both shaft and hub
43   Which of the following key is preferred for the condition when a large amount of impact type torque is to be transmitted in both directions of rotation?
    (A)   Woodruff key
    (B)   Feather key
    (C)   Gib-head key
    (D)   Tangent key
44   The type of stresses developed in the key is/are
    (A)   Shear stress alone
    (B)   Crushing stress alone
    (C)   Both shear and crushing stresses
    (D)   Shearing, crushing and bending stresses
45   A saddle key __________ power through frictional resistance only.
    (A)   Transmits
    (B)   Does not transmit
46   A tapered key that fits in a keyway in the hub and the bottom of which is shaped to fit the curved surface of the shaft is known as the hollow saddle key.
    (A)   Correct
    (B)   Incorrect
47   Two shafts A and B of solid circular cross-section are identical except for their diameters dA and dB. The ratio of power transmitted by the shaft A to that of shaft B is
    (A)   dA/dB
    (B)   (dA)2/(dB)2
    (C)   (dA)3/(dB)3
    (D)   (dA)4/(dB)4
48   A transmission shaft subjected to bending loads must be designed on the basis of
    (A)   Maximum normal stress theory
    (B)   Maximum shear stress theory
    (C)   Maximum normal stress and maximum shear stress theories
    (D)   Fatigue strength
49   Which of the following loading is considered for the design of axles?
    (A)   Bending moment only
    (B)   Twisting moment only
    (C)   Combined bending moment and torsion
    (D)   Combined action of bending moment, twisting moment and axial thrust
50   When a shaft is subjected to a bending moment M and a twisting moment T, then the equivalent twisting moment is equal to
    (A)   M + T
    (B)   M2+ T2
    (C)   SQRT(M2+T2)
    (D)   SQRT(M2-T2)
51   The maximum shear stress theory is used for
    (A)   Brittle materials
    (B)   Ductile materials
    (C)   Plastic materials
    (D)   Non-ferrous materials
52   The design of shafts made of brittle materials is based on
    (A)   Guest’s theory
    (B)   Rankine’s theory
    (C)   St. Venant’s theory
    (D)   Von Mises Theory
53   When the shaft is subjected to pure bending moment, the bending stress is given by?
    (A)   32M/πd3
    (B)   16M/πd3
    (C)   8M/πd3
    (D)   None of the listed
54   When a shaft is subjected to combined twisting moment (T) and bending moment (M), then the equivalent twisting moment is equal to
    (A)   1/2 √ (M2+T2)
    (B)   √(M2+T2)
    (C)   1/2 (M+ √(M2+T2))
    (D)   M+ √(M2+T2)
55   A circular shaft can transmit a torque of 5 kN-m. If the torque is reduced to 4 kN-m, then the maximum value of bending moment that can be applied to the shaft is
    (A)   1 kN-m
    (B)   2 kN-m
    (C)   3 kN-m
    (D)   4 kN-m
56   The angle of twist of shaft is
    (A)   Directly proportional to (shaft diameter)2
    (B)   Inversely proportional to (shaft diameter)2
    (C)   Directly proportional to (shaft diameter)4
    (D)   Inversely proportional to (shaft diameter)4
57   If T=torque, θ=angle of twist, J=polar moment of inertia, G=modulus of rigidity, then the torsional rigidity is given as
    (A)   T/θ
    (B)   Gθ
    (C)   GJ
    (D)   θ
58   Which of the following is not an assumption in derivation of torsion equation?
    (A)   Circular shaft remains circular after twisting
    (B)   Plane section of the shaft remain plan after twisting
    (C)   Material of shaft is isotropic
    (D)   Angle of twist is proportional to radius
59   A shaft
    (A)   Is always subjected to pure torsion
    (B)   Combination of M & T but no end thrust
    (C)   Combination of torque & end thrust but no bending moment
    (D)   May be subjected to a combination of M, T and end thrust
60   For same weight, same material, same length
    (A)   Solid shaft is always stronger than a hollow shaft
    (B)   Sold shaft is always weaker than the hollow shaft and strength ratio will depend upon Do/Di of hollow shaft
    (C)   Strengths of both the shafts are equal
    (D)   None of the above
61   Magnitude of shear stress induced in a shaft due to applied torque varies from
    (A)   Maximum at center to zero at circumference
    (B)   Maximum at center to minimum (not-zero) at circumference
    (C)   Zero at center to maximum at circumference.
    (D)   Minimum (not zero) at center to maximum at circumference
62   Maximum shear stress of a solid shaft is given by
    (A)   16T/πd
    (B)   16T/πd2
    (C)   16T/πd3
    (D)   16T/πd4
63   The angle of twist is ————- proportional to the twisting moment.
    (A)   Directly
    (B)   Inversely
    (C)   Indirectly
    (D)   Reversely
64   The polar moment of inertia of a solid circular shaft of diameter (d) is
    (A)   πd2/16
    (B)   πd3/32
    (C)   πd4/32
    (D)   πd4/64
65   The polar moment of inertia of a hollow shaft of outer diameter (D) and inner diameter (d) is given by.
    (A)   π (D3-d3) /32
    (B)   π(D4-d4) /32
    (C)   π(D4-d4) /16
    (D)   π(D4-d4/d) /32
66   For same length, same material, same torque transmitted
    (A)   Weight of solid shaft is less than weight of hollow shaft
    (B)   Weight of solid shaft is more than weight of hollow shaft
    (C)   Weight of hollow and solid shafts will be same
    (D)   Sometime more sometime less
67   Two shafts in torsion will have equal strength if
    (A)   Only diameter of the shafts is same
    (B)   Only angle of twist of the shaft is same
    (C)   Only material of the shaft is same
    (D)   Only torque transmitting capacity of the shaft is same
68   A Shaft is said to be in pure torsion if
    (A)   Turning moment is applied at one end and the other end is free
    (B)   Turning force is applied at one end and the other end is free
    (C)   Two opposite turning moments are applied to the shaft
    (D)   Combination of torsional load and bending load is applied to the shaft
69   In power transmission equation, P=2πNT/60
    (A)   P is in kW and T is maximum torque
    (B)   P is in NM/sec and T is maximum torque
    (C)   P is in NW/sec and T is mean torque
    (D)   P is in kW and T is mean torque
70   Which material is suitable for shaft material?
    (A)   High speed steel
    (B)   Stainless steel or high carbon steel
    (C)   Grey cast iron
    (D)   Steel having approx. 0.4% carbon 0.8% manganese
71   If diameter of a shaft is doubled the power transmitted capacity will be
    (A)   Either twice of half
    (B)   Four times
    (C)   Eight times
    (D)   Same
72   Strength of a shaft
    (A)   Is equal to maximum shear stress in the shaft at the time of elastic failure
    (B)   Is equal to maximum shear stress in the shaft at the time of rupture
    (C)   Is equal to torsional rigidity
    (D)   Is ability to transmit twisting moment
73   Which of the following is not designed under torsion equation?
    (A)   Spindle
    (B)   Axle
    (C)   Low-cost shaft
    (D)   Shaft with variable diameter
74   Which of the following is incorrect?
    (A)   In torsion equation, we use mean torque
    (B)   In torsion equation, we use maximum torque
    (C)   Many shafts are designed under combined bending and torsion load
    (D)   Shafts are also designed for torsional rigidity
75   Which of the following is incorrect?
    (A)   In a solid shaft maximum shear stress occurs at radius = radius of shaft
    (B)   In a solid shaft maximum shear stress occurs at the center
    (C)   In a hollow shaft maximum shear stress occurs at outer radius
    (D)   In a hollow shaft minimum shear stress occurs at inner radius
76   The following option is correct
    (A)   There is neither advantage nor disadvantage in transmitting power at high speed
    (B)   There is advantage in transmitting power at high speeds
    (C)   There is disadvantage in transmitting power at high speeds
    (D)   There is advantage in transmitting power at high speed provided shafts are made of high-speed steel
77   The shaft is always stepped with ________ diameter at the middle portion and __________ diameter at the shaft ends.
    (A)   Minimum, maximum
    (B)   Maximum, minimum
    (C)   Minimum, minimum
    (D)   Zero, infinity
78   ______ is used for a shaft that supports rotating elements like wheels, drums or rope sleeves.
    (A)   Spindle
    (B)   Axle
    (C)   Shaft
    (D)   None of the listed
79   Counter shaft is a secondary shaft.
    (A)   TRUE
    (B)   FALSE
80   Which of the following act on shafts?
    (A)   Torsional moment
    (B)   Bending Moment
    (C)   Both torsional and bending
    (D)   None of the mentioned
81   When the shaft is subjected to pure torsional moment, the torsional stress is given by?
    (A)   None of the listed
    (B)   32M/πd3
    (C)   16M/πd3
    (D)   8M/πd3
82   Which property is not required for shaft materials?
    (A)   High shear and tensile strength
    (B)   Good machinability
    (C)   High fatigue strength
    (D)   Good castability
83   When a solid shaft is subjected to torsion, the shear stress induced in the shaft at its center is
    (A)   Minimum
    (B)   Zero
    (C)   Maximum
    (D)   Average
84   When a shaft is subjected to a twisting moment, every cross-section of the shaft will be under
    (A)   Tensile stress
    (B)   Compressive stress
    (C)   Shear stress
    (D)   Bending stress
85   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
    (C)   Torsional rigidity
    (D)   Flexural rigidity
86   A shaft is designed on the basis of rigidity and stiffness.
    (A)   Correct
    (B)   Incorrect
87   Identify the machine element

    (A)   Hollow shaft
    (B)   Stepped shaft
    (C)   Splined shaft
    (D)   None of the above
88   Which of the following are functions of bearings?
    (A)   Ensure free rotation of shaft with minimum friction
    (B)   Holding shaft in a correct position
    (C)   Transmit the force of the shaft to the frame
    (D)   All of the listed
89   A coupling is a mechanical device that temporarily joins two rotating shafts to each other.
    (A)   TRUE
    (B)   FALSE
90   Oldham coupling is used to connect two shafts having intersecting axes.
    (A)   TRUE
    (B)   FALSE
91   A muff coupling is connecting two shafts. The torque involved is 650N-m. The shaft diameter is 45mm with length and breadth of the key being 14mm and 80mm respectively. Find the shear stress induced in the key.
    (A)   30.2N/mm2
    (B)   25.8N/mm2
    (C)   34.4N/mm2
    (D)   None of the listed
92   A muff coupling is connecting two shafts. The torque involved is 650N-m. The shaft diameter is 45mm with length and height of the key being 14mm and 80mm respectively. Find the compressive stress induced in the key.
    (A)   70.1 N/mm²2
    (B)   51.6N/mm2
    (C)   45.5N/mm2
    (D)   None of the listed
93   Calculate the force acting on each pin in flexible coupling if torque transmitted is 397N-m and PCD=120mm with number of pins 6.
    (A)   1400.3N
    (B)   1102.8N
    (C)   1320.3N
    (D)   None of the listed
94   Entire torque is transmitted by friction in the clamp coupling.
    (A)   TRUE
    (B)   FALSE
95   Does shaft have to be shifted in axial direction to remove clamp coupling.
    (A)   Yes
    (B)   No
96   If shaft diameter is 40mm, calculate the diameter of sleeves in clamp coupling.
    (A)   100mm
    (B)   80mm
    (C)   60mm
    (D)   40mm
97   If shaft diameter is 40mm, calculate the length of sleeves in clamp coupling.
    (A)   80mm
    (B)   140mm
    (C)   100mm
    (D)   120mm
98   If 8 bolts are emplaced in a clamp coupling with shaft diameter 80mm d, calculate the tensile force on each bolt if coefficient of friction is 0.3 and torque transmitted is 4000N-m.
    (A)   51234.4N
    (B)   45968.3N
    (C)   41666.7N
    (D)   None of the above
99   If 8 bolts are emplaced in a clamp coupling with shaft diameter 80mm d, calculate the diameter of each bolt if coefficient of friction is 0.3 and torque transmitted is 4000N-m. Permissible tensile stress is 80N/mm².
    (A)   27mm
    (B)   25mm
    (C)   23mm
    (D)   21mm
100   Power is transmitted by flange only in rigid flange coupling.
    (A)   TRUE
    (B)   FALSE

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