Latest Machine Design Questions and Answers

Machine Design Questions and Answers

1. The ultimate strength of steel in tension in
comparison to shear is in the ratio of
(a) 1 : l
(b) 2:1
(c) 3 : 2
(d) 2 : 3
(e) 1 : 2
Ans: c
2. The permissible stress for carbon steel under
static loading is generally taken as
(a) 2000-3000 kg/pm2
(b) 3000-4000 kg/cm2
(c) 4000-4500 kg/cm2
(d) 7500-10,000 kg/cm2
(e) 10,000-15,000 kg/cm2.
Ans: c
3. The property of a material which enables it to
resist fracture due to high impact loads is known as
(a) elasticity
(b) endurance
(c) strength
(d) toughness
(e) resilience.
Ans: d
4. A hot short metal is
(a) brittle when cold
(b) brittle when hot
(c) brittle under all conditions
(d) ductile at high temperature
(e) hard when hot.
Ans: b
5. Guest's theory of failure is applicable for
following type of materials
(a) brittle
(b) ductile
(c) elastic
(d) plastic
(e) tough.
Ans: b
6. Rankine's theory of failure is applicable for
following type of materials
(a) brittle
(b) ductile
(c) elastic
(d) plastic
(e) tough.
Ans: a
7. If an unsupported uniform cross sectional elastic
bar is subjected to a longitudinal impact from a rigid
bob moving with velocity v, then a compressive
wave of intensity sc is propagated through the bar
as follows
(a) vpE
(b) vVvF
(c) WpE/2
(d) IvHpE
(e) none of the above, where E = modulus of
elasticity and p = mass density.
Ans: a
8. Tensile strength of a mild steel specimen can be
roughly predicted from following hardness test
(a) Brinell
(b) Rockwell
(c) Vicker
(d) Shore's sceleroscope
(e) none of the above.
Ans: a
9. Resilience of a material is important, when it is
subjected to
(a) combined loading
(b) fatigue
(c) thermal stresses
(d) wear and tear
(e) shock loading.
Ans: e
10. In the case of an elastic bar fixed at upper end
and loaded by a falling weight at lower end, the
shock load produced can be decreased by
(a) decreasing the cross-section area of' bar
(b) increasing the cross-section area of bar
(c) remain unaffected with cross-section area
(d) would depend upon other factors
(e) none of the above.
Ans: a
11. .Other method of reducing shock load in the
above case can be
(a) to decrease length
(b) to increase length
(c) unaffected by length
(d) other factors would decide same
(e) none of the above.
Ans: b
12. If a load W is applied instantaneously on a bar;
then the stress induced in bar will
(a) be independent of ratio of mass of load W to
mass of bar (y)
(b) increase with increase in y
(c) decrease with decrease in y
(d) depend on other considerations
(e) none of the above.
Ans: a
13. Brittle coating technique is used for
(a) determining brittleness
(b) protecting metal against corrosion
(c) protecting metal against wear and tear
(d) experimental stress analysis
(e) non-destructive testing of metals.
Ans: d
14. Stress concentration is caused due to
(a) variation in properties of material from point to
point in a member
(b) pitting at'points or areas at which loads on a
member are applied
(c) abrupt change of section
(d) all of the above
(e) none of the above.
Ans: d
15. The endurance limit of a material with finished
surface in comparison to rough surface is
(a) more
(b) less
(c) same
(d) more or less depending on quantum of load
(e) unpredictable.
Ans: a
16. Plastic flow in ductile materials
(a) increases the seriousness of static load-ing
stress concentration
(b) lessens the seriousness of static load¬ing
stress concentration
(c) has no effect on it
(d) depends on other considerations
(e) none of the above.
Ans: b
17. 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
(e) unpredictable.
Ans: c
18. The fatigue life of a part can be improved by
(a) electroplating
(b) polishing
(c) coating
(d) shot peening
(e) heat treating.
Ans: d
19. Stress concentration in static loading is more
serious in
(a) ductile materials
(b) brittle materials
(c) equally serious in both cases
(d) depends on other factors
(e) unpredictable.
Ans: b
20. Stress concentration in cyclic loading is more
serious in
(a) ductile materials
(b) brittle materials
(c) equally serious in both cases
(d) depends on other factors
(e) unpredictable.
Ans: a
21. Endurance limit or fatigue limit is the maximum
stress that a member can withstand for an infinite
number of load applications without failure when
subjected to
(a) dynamic loading
(b) static loading
(c) combined static and dynamic loading
(d) completely reversed loading
(e) all of the above.
Ans: d
22. Pick up wrong statement. Fatigue strength can
be increased by
(a) cold working
(b) shot peening
(c) grinding and lapping surface
(d) hot working
(e) using gradual changes of section.
Ans: d
23. Which of the following is not correct procedure
to increase the fatigue limit
(a) cold working
(b) shot peening
(c) surface decarburisation
(d) under-stressing
(e) all of the above.
Ans: c
24. Coaxing is the procedure of increasing
(a) metal strength by cycling
(b) metal hardness by surface treatment
(c) metal resistance to corrosion by coating
(d) fatigue limit by overstressing the metal by
successively increasing loadings
(e) none of the above.
Ans: d
25. 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
(e) none of the above.
Ans: a
26. The notch angle of the Izod impact test
specimen is
(a) 10°
(b) 20°
(c) 30°
(d) 45°
(e) 60°.
Ans: d
27. In Vicker's hardness testing, the pyramid
indentor apex is
(a) 40°
(b) 122°
(c) 136°
(d) 152°
(e) 161°.
Ans: c
28. Which is correct statement ?
Stress concentration in cyclic 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
(e) none of the above.
Ans: c
29. In testing a material for endurance strength, it is
subjected to
(a) static load
(b) dynamic load
(c) impact load
(d) static as well as dynamic load
(e) completely reversed load.
Ans: e
30. If a material fails below its yield point, failure
would be due to
(a) straining
(b) fatigue
(c) creep
(d) sudden loading
(e) impact loading.
Ans: b
31. The fatigue limit of a material
(a) is greatly decreased by poor surface conditions
(b) remains same irrespective of surface conditions
(c) depends mainly on core composition
(d) is dependent upon yield strength of material
(e) none of the above.
Ans: a
32. Cold working
(a) increases the fatigue strength
(b) decreases the fatigue strength
(c) has no influence on fatigue strength
(d) alone has no influence on fatigue strength
(e) none of the above.
Ans: a
33. Yield point in fatigue loading as compared to
static loading is
(a) same
(b) higher
(c) lower
(d) depends on other factors
(e) none of the above.
Ans: c
34. Residual stress in materials
(a) acts when external load is applied
(b) becomes zero when external load is removed
(c) is independent of external loads
(d) is always harmful
(e) is always beneficial.
Ans: c
35. The building up of worn and uridersized parts,
subjected to repeated loads by electroplating is
(a) best method
(b) extremely hazardous
(c) has no effect as regards fatigue strength
(d) cheapest method
(e) all of the above.
Ans: a
36. In nitrated parts, the origins of the fatigue
cracks will occur at
(a) surface
(b) just below the surface
(c) within the core
(d) could occur anywhere
(e) none of the above.
Ans: e
37. Which process will increase the fatigue duration
of parts ?
(a) finishing and polishing
(b) shot-peening
(c) decarburisation
(d) electroplating
(e) all of the above".
Ans: b
38. Which is correct statement ?
(a) a member made of steel will generally be more
rigid than a member of equal load-carrying ability
made of cast iron
(b) a member made of cast iron will generally be.
more rigid than a member of equal load carrying
ability made of steel
(c) both will be equally rigid
(d) which one is rigid will depend on several other
factors
(e) none of the above.
Ans: b
39. Resistance to fatigue of a material is measured
by
(a) Young's modulus
(b) coefficient of elasticity
(c) elastic limit
(d) ultimate tensile strength
(e) endurance limit.
Ans: e
40. In most machine members, the damping
capacity of the material should be
(a) low
(b) zero
(c) high
(d) could be anything
(e) none of the above.
Ans: c
41. The ratio of endurance limit in shear to the
endurance limit in flexure is
(a) 0.33
(b) 0.4
(c) 0.5
(d) 0.55
(e) 0.6
Ans: d
42. For steel, the ultimate strength in shear as
compared to ultimate strength in tension is
(a) same
(b) 1/2
(c) 1/3
(d) 1/4
(e) 2/3
Ans: e
43. The endurance limit in shear of carbon steel can
be obtained by multiplying the endurance limit in
flexure by a factor of
(a) 0.25
(b) 0.45
(r) 0.55
(d) 0.65
(e)0.75.
Ans: e
44. At low temperatures (say 75°C) the notched-bar
impact value of steel
(a) increases markedly
(b) decreases markedly
(c) remains same
(d) depends on heat treatment carried out
(e) none of the above.
Ans: b
45. A bolt
(a) has a head on one end and a nut fitted to the
other
(b) has head at one end and other end fits into a
tapped hole in the other part to be joined
(c) has both the ends threaded
(d) is provided with pointed threads
(e) requires no nut.
Ans: a
46. The crest diameter of a screw thread is same
as
(a) major diameter
(b) minor diameter
(c) pitch diameter
(d) core diameter
(e) none of the above.
Ans: a
47. If d is the diameter of bolt hole then for a
flanged pipe joint to be leak proof, the
circumferential pitch of the bolts should be
(a) lOVZ
(b) 10VZtol5Vd
(c) 15Vdto20VZ
(d) 20Vdto30Vd
(e) 30V5"to40Vd.
Ans: d
48. Maximum principal stress theory is applicable
for
(a) ductile materials
(b) brittle materials
(c) elastic materials
(d) all of the above
(e) none of the above.
Ans: b
49. The following type of nut is used with alien bolt
(a) alien nut
(b) hexagonal nut
(c) slotted nut
(d) castle nut
(e) any one of the above.
Ans: e
50. A stud
(a) has a head on one end and a nut fitted to the
other
(b) has head at one end and other end fits into a
tapped hole in the other part to be joined
(c) has both the ends threaded
(d) has pointed threads
(e) requires locking nuts.
Ans: c
51. Shear stress theory is applicable for
(a) ductile fnaterials
(b) brittle materials
(c) elastic materials
(d) all of the above
(e) none of the above.
Ans: a
52. A tap bolt
(a) has a head on one end and a nut fitted to the
other
(b) has head at one end and other end fits into a
tapped hole in the other part \o be joined
(c) has both the ends threaded
(d) has pointed threads
(e) requires locking devices.
Ans: b
53. 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
(e) British Association thread.
Ans: d
54. The included angle in unified of American
National threads is
(a) 60°
(b) 55°
(c) 47°
(d) 29°
(e) none of the above.
Ans: a
55. The function of a washer is to
(a) provide cushioning effect
(b) provide bearing area
(c) absorb shocks and vibrations
(d) provide smooth surface in place of rough
surface
(e) act as a locking device.
Ans: b
56. Cap 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 be-tween parts
(d) provided with detachable caps
(e) similar to stud.
Ans: a
57. An alien bolt is
(a) self locking bolt
(b) same as stud
(c) provided with hexagonal depression in head
(d) used in high speed components
(e) provided with countersunk head.
Ans: c
58. The deflection of a cantilever beam under load W
is 8. If its width is halved, then the deflection under
load W will be
(a) 28
(b) 8/2
(c) 48
(d) 8/4
(e) none of the above.
Ans: c
59. Ball bearing type screws are found in following
application
(a) screw jack
(b) aeroplane engines
(c) crane
(d) steering mechanism
(e) bench vice.
Ans: d
60. 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 be-tween parts
(d) similar to stud
(e) none of the above.
Ans: c
61. A self locking screw has
(a) fine threads
(b) coarse threads
(c) coefficient of friction > tangent of load angle
(d) hole for inserting split pin
(e) two nuts for locking.
Ans: c
62. The designation M 33 x 2 of a bolt means
(a) metric threads of 33 nos in 2 cm.
(b) metric threads with cross-section of 33 mm
(c) metric threads of 33 mm outside diameter and 2
mm pitch
(d) bolt of 33 mm nominal diameter having 2 threads
per cm
(e) none of the above.
Ans: c
63. Machine 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 be-tween two
parts
(d) similar to stud
(e) none of the above.
Ans: b
64. Rivets are generally specified by
(a) thickness of plates to be riveted
(b) length of rivet
(c) diameter of head
(d) nominal diameter
(e) all of the above.
Ans: d
65. The edges of a boiler plate are bevelled to an
angle of
(a) 30°
(b) 45°
(c) 60°
(d) 80°
(e) 85°.
Ans: d
66. Which of the following is a permanent
fastening ?
(a) bolts
(b) keys
(c) cotters
(d) rivets
(e) screws.
Ans: d
67. In order to avoid tearing of the plate at edge, the
distance from the center line of the rivet hole to the
nearest edge of the plate in terms of dia. of rivet d
should be equal to
(a) d
(b) 1.25 d
(c) 1.5 d
(d) 1.75 d
(e) 2 d.
Ans: c
68. 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
(e) 0.75.
Ans: b
69. Transverse fillet welded joints are designed for
(a) tensile strength
(b) compressive strength
(c) shear strength
(d) bending strength
(e) torsional strength.
Ans: a
70. Jam 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 a screw
(c) a hard fiber 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 spitted and bent in reverse direction at other
end
(e) none of the above.
Ans: a
71. The pitch of threads on a Jock nut in
comparison to pitch of nut is
(a) same
(b) coarser
(c) finer
(d) very coarse
(e) very fine.
Ans: a
72.Buttress threads are usually found on
(a) screw cutting lathes
(b) feed mechanisms
(c) spindles of bench vices
(d) screw jack
(e) railway carriage couplings.
Ans: e
73. In order to obtain bolt of uniform strength
(a) increase shank diameter
(b) increase its length
(c) drill an axial hole through head up to threaded
portion so that shank area is equal to root area of
thread
(d) tighten die bolt properly
(e) all of the above.
Ans: c
74. A key capable of tilting in a recess milled out in
a shaft is known as
(a) wood-ruff key
(b) feather key
(c) flat saddle key
(d) gib head key
(e) hollow saddle key.
Ans: a
75. A key made from a cylindrical disc having
segmental cross-section, is known as
(a) wood-ruff key
(b) feather key
(c) flat saddle key
(d) gib head key
(e) hollow saddle key.
Ans: a
76. A tapered key which fits in a keyway in the hub
and is flat on the shaft, is known as
(a) wood-ruff key
(b) feather key
(c) flat saddle key
(d) gib head key
(e) hollow saddle key.
Ans: c
77. Fibrous fracture occurs in
(a) ductile material
(b) brittle material
(c) elastic material
(d) hard material
(e) all of the above.
Ans: a
78. Turn buckle has
(a) right hand threads on bout ends
(b) left hand threads on both ends
(c) left hand threads on one end and right hand
threads on other end
(d) no threads
(e) threads in middle portion.
Ans: c
79. Eye bolts are used for
(a) foundation purposes
(b) locking devices *
(c) absorbing shock and vibrations
(d) transmission of power
(e) lifting and transportation of machines and
cubicles.
Ans: e
80. Elastic nut is a locking device in which
(a) one small 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 a screw
(c) hard fiber or nylon cotter is recessed in the nut
and becomes threaded as the nut is stewed 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
other end
(e) none of the above,
Ans: c
81. 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) 102 d
(b) 124 d
(c) 138 d
(d) 151 d
(e) 168 d.
Ans: e
82. If threads on a bolt are left hand, threads on nut
will be
(a) right hand with same pitch
(b) left hand with same pitch
(c) could be left or right hand
(d) right hand with fine pitch
(e) left hand with fine pitch.
Ans: b
83. Taper usually provided on cotter is
(a) 1 in 5
(b) 1 in 10
(c) 1 in 24
(d) 1 in 40
(e) 1 in 50.
Ans: c
84. Applications in which stresses are encountered
in one direction only uses following type of threads
(a) metric
(b) buttress
(c) acme
(d) square
(e) BSW.
Ans: b
85. The draw of cotter need not exceed
(a) 3 mm
(b) 5 mm
(c) 10 mm
(d) 20 mm
(e) 25 mm.
Ans: a
86. A bench vice has following type of threads
(a) metric
(b) square
(c) buttress
(d) acme
(e) BSW.
Ans: d
87. The valve rod in a steam engine is connected to
an eccentric rod by
(a) cotter joint
(b) bolted joint
(c) kunckle joint
(d) universal coupling
(e) gib and cotter joint.
Ans: c
88. 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 fiber 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
(e) none of the above.
Ans: b
89. Taper on the cotter and slot is provided
(a) on both the sides
(b) on one side only
(c) on none of the sides
(d) may be provided anywhere
(e) none of the above.
Ans: b
90. The function of cutting oil when threading a pipe
is to
(a) provide cooling action
(b) lubricate the dies
(c) help remove chips
(d) all of the above
(e) none of the above.
Ans: d
91. Silver-based solder is used for
(a) flaring
(b) brazing
(c) soft soldering
(d) fusion welding
(e) none of the above.'
Ans: b
92. For tight leakage joints, following type of thread
is best suited
(a) metric
(b) buttress
(c) square
(d) acme
(e) NPT (national pipe threads).
Ans: e
93. In order to permit the thermal expansion/
contraction of tubing, it should be
(a) crimped
(b) honed
(c) flared
(d) bent
(e) none of the above.
Ans: d
94. A tube has the following advantage over pipe
(a) lighter and easier to handle
(b) greater shock absorption
(c) smoother inside walls
(d) all of the above
(e) none of the above.
Ans: d
95. 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
(e) universal coupling.
Ans: a
96. A backing ring is used inside the pipe joint when
making a
(a) butt weld
(b) fillet weld
(c) sleeve weld
(d) socket weld
(e) tube weld.
Ans: a
97. The shear plane in case of bolts should
(a) be across threaded portion of shank
(b) be parallel to axis of bolt
(c) be normal to threaded portion of shank
(d) never be across the threaded portion
(e) none of the above.
Ans: d
97. Castle 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 is middle of nut and then slot
reduced by tightening a screw
(c) a hard fiber 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 spitted and bent in reverse direction at
other end
(e) none of the above.
Ans: d
98. When a nut is tightened by plaping a washer
below it, the bolt will be subjected to following type
of loads
(a) compression
(b) tension
(c) shear
(d) combined loads
(e) all of the above.
Ans: b
99. Gear box is used
(a) to produce torque
(b) for speed reduction
(c) to obtain variable speeds
(d) to increase efficiency of system
(e) to damp out vibrations.
Ans: c
100. The edges of the plates for cylindrical vessels
are usually bevelled to an angle of 80° for
(a) reducing stress concentration
(b) ease of manufacture
(c) safety
(d) fullering and caulking
(e) all of the above.
Ans: d
101. The piston rod of a steam engine is usually
connected to the crosshead by means of
(a) bolted joint
(b) kunckle joint
(c) cotter joint
(d) universal joint
(e) universal coupling.
Ans: c
102. Which of the following pipe joints would be
suitable for pipes carrying steam
(a) flanged
(b) threaded
(c) bell and spigot
(d) expansion
(e) compression.
Ans: d
103. Spring index is
(a) ratio of coil diameter to wire diameter
(b) load required to produce unit deflection
(c) its capability of storing energy
(d) indication of quality of spring
(e) nothing.
Ans: a
104. The shearing stresses in the inner face as
compared to outer face of the wire in a heavy close
coiled spring is
(a) larger
(b) smaller
(c) equal
(d) larger/smaller depending on diameter of spring
coil
(e) unpredictable.
Ans: a
105. Form coefficient of spring is
(a) ratio of coil diameter to wire diameter
(b) load required to produce unit deflection
(c) its capability of storing energy
(d) concerned With strength of wire of spring
(e) nothing
Ans: c
106. Spring stiffness is
(a) ratio of coil diameter to wire diameter
(b) load required to produce unit deflection
(c) its capability of storing energy
(d) its ability to absorb shocks
(e) none of the above.
Ans: b
107. When two springs are in series (having
stiffness K), the equivalent stiffness will be
(a) K
(b) K/2
(c) 2K
(d) KIA
(e) UK.
Ans: b
108. When a close coiled helical spring is
compressed, its wire is subjected to
(a) tension
(b) shear
(c) compression
(d) all of the above
(e) none of the above.
Ans: a
109. If a spring is cut down into two springs, the
stiffness of cut springs will be
(a) half
(b) same
(c) double
(d) unpredictable
(e) none of the above.
Ans: c
110. Belt slip may occur due to
(a) heavy load
(b) loose belt
(c) driving pulley too small
(d) all of the above
(e) none of the above.
Ans: d
111. Aircraft body is usually fabricated by
(a) welding
(b) precasting
(c) rivetting
(d) casting
(e) unconventional methods.
Ans: c
112. If two springs are in parallel then their overall
stiffness will be
(a) half
(b) same
(c) double
(d) unpredictable
(e) none of the above.
Ans: c
113. 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
(e) none of the above.
Ans: a
114. Antifriction bearings are
(a) sleeve bearings
(b) hydrodynamic bearings
(c) thin lubricated bearings
(d) ball and roller bearings
(e) none of the above.
Ans: e
115. If p = bearing pressure on projected bearing
area, z = absolute viscosity of lubricant, and N =
speed of journal, then the bearing characteristic
number is given by
(a) ZN/p
(b) p/ZN
(c) Z/pN
(d) N/Zp
(e) Zp/N.
Ans: a
116. 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
(e) 25 microns.
Ans: c
117. In hydrostatic 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
(e) none of the above.
Ans: b
118. Oil in journal bearing should be applied at the
point where load is
(a) nil or lightest
(b) maximum
(c) average
(d) any one of the above
(e) unpredictable.
Ans: a
119. 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
(e) none of the above.
Ans: c
120. In oilness 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 required to be applied after some
intervals
(e) none of the above.
Ans: c
121. In V-belt drive, belt touches
(a) at bottom
(b) at sides only
(c) both at bottom and sides
(d) could touch anywhere
(e) none of the above.
Ans: b
122. 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) unpredictable
(e) none of the above.
Ans: a
123. In cross or regular lay ropes
(a) direction of twist of wires in strands is opposite
to the direction of twist of strands
(b) direction of twist of wires and strands are same
(c) wires in two adjacent strands are twisted in
opposite direction
(d) wires are not twisted
(e) none of the above.
Ans: a
124. In standard taper roller bearings, the angle of
taper of outer raceway is
(a) 5°
(b) 8°
(c) 15°
(d) 25°
(e) 40°.
Ans: d
125. In composite or reverse laid ropes
(a) direction of twist of wires in strands is opposite
to the direction of twist of strands
(b) direction of twist of wires and strands are same
(c) wires in two adjacent strands are twisted in
opposite direction
(d) wires are not twisted
(e) none of the above.
Ans: c
126. Whether any core is required in wire ropes
(a) yes
(b) no
(c) sometimes
(d) rarely
(e) very often.
Ans: a
127. 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 x diameter of bolt
(c) 1.25 x diameter of bolt
(d) 1.5 x diameter of bolt
(e) 0.5 x diameter of bolt.
Ans: a
128. Basic shaft is one
(a) whose upper deviation is zero
(b) whose lower deviation is zero
(c) whose lower as well as upper deviations are
zero
(d) does not exist
(e) none of the above.
Ans: a
129. Basic hole is one
(a) whose upper deviation is zero
(b) whose lower deviation is zero
(c) whose lower as well as upper deviations are
zero
(d) does not exist
(e) none of the above.
Ans: b
130. I.S. specifies following total number of grades
of tolerances
(a) 18
(b) 16
(c) 20
(d) 22
(e) 14.
Ans: a
131. For standard coarse threads of nut, the threads
will be as strong in failure by shear as the bolt in
tension, if the height of nut (h) is approximately
(a) 0.4 times
(b) 0.6 times
(c) 0.7 times
(d) 0.8 times
(e) 0.9 times the normal diameter of bolt.
Ans: a
132. Allen bolts are
(a) self locking bolts
(b) designed for shock load
(c) used in aircraft application
(d) provided with hexagonal depression in head
(e) uniform strength bolts.
Ans: d
133. The resultant axial load on a bolt depends on
(a) initial tension
(b) external load applied
(c) relative elastic yielding (springness) of the bolt
and the connected member
(d) (a) and (b) above
(e) (a), (b) and (c) above.
Ans: e
134. The connecting rod bolts are tightened up so
that tightening stress
(a) is just sufficient to hold parts together
(b) approaches yield point
(c) is 50% of yield point
(d) is about yield point divided by safety factor
(e) none of the above.
Ans: b
135. The connecting rod bolts are tightened up with
initial tension greater than the external load so that
(a) joint may not open up
(b) bolts are weakest elements
(c) the resultant load on the bolt would not be
affected by the external cyclic load
(d) bolts will not loosen during service
(e) none of the above.
Ans: c
136. If an application calls for stresses on screw
threads in one direction only, then the following type
of thread would be best suited
(a) square
(b) acme
(c) buttress
(d) BSW
(e) metric.
Ans: c
137. When a bolt is subjected to shock loading, the
resilience of the bolt should be considered in order
to prevent breakage at
(a) shank
(b) head
(c) in the middle
(d) at the thread
(e) anywhere in the bolt.
Ans: d
138. The shock absorbing capacity of a bolt can be
increased by
(a) tightening it properly
(b) increasing shank diameter
(c) grinding the shank
(d) using washer
(e) making shank diameter equal to core diameter
of thread.
Ans: e