Important Machine Design Objective Questions For Competitive’s Part – 2
1.In order to permit the thermal expansion/contraction of tubing, it should be
crimped
honed
flared
bent
none of the above.
ANSWER : s: d
2.Taper usually provided on cotter is
1 in 5
1 in 10
1 in 24
1 in 40
1 in 50.
ANSWER : : 1 in 24
3.Castle nut is a locking device in which
one smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
a slot is cut partly is middle of nut and then slot reduced by tightening a screw
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
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
none of the above.
ANSWER : : 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
4.Taper on the cotter and slot is provided
on both the sides
on one side only
on none of the sides
may be provided anywhere
none of the above.
ANSWER : : on one side only
5.A tube has the following advantage over pipe
lighter and easier to handle
greater shock absorption
smoother inside walls
all of the above
none of the above.
ANSWER : : all of the above
6.The piston rod of a steam engine is usually connected to the cross head by means of
bolted joint
knuckle joint
cotter joint
universal joint
universal coupling.
ANSWER : : cotter joint
7.The shear plane in case of bolts should
be across threaded portion of shank
be parallel to axis of bolt
be normal to threaded portion of shank
never be across the threaded portion
none of the above.
ANSWER : : never be across the threaded portion
8.The draw of cotter need not exceed
3 mm
5 mm
10 mm
20 mm
25 mm.
ANSWER : : 3 mm
9.The edges of the plates for cylindrical vessels are usually bevelled to an angle of 80� for
reducing stress concentration
ease of manufacture
safety
fullering and caulking
all of the above.
ANSWER : : fullering and caulking
10.The valve rod in a steam engine is connected to an eccentric rod by
cotter joint
bolted joint
kunckle joint
universal coupling
gib and cotter joint.
ANSWER : : kunckle joint
11.Silver-based solder is used for
flaring
brazing
soft soldering
fusion welding
none of the above.’
ANSWER : : brazing
12.The function of cutting oil when threading a pipe is to
provide cooling action
lubricate the dies
help remove chips
all of the above
none of the above.
ANSWER : : all of the above
13.A backing ring is used inside the pipe joint when making a
butt weld
fillet weld
sleeve weld
socket weld
tube weld.
ANSWER : : butt weld
14.The strap end of a connecting rod of steam engine is joined by
big of cotter joint
sleeve and cotter joint
spigot socket cotter joint
knuckle joint
universal coupling.
ANSWER : : big of cotter joint
15.Spring index is
ratio of coil diameter to wire diameter
load required to produce unit deflection
its capability of storing energy
indication of quality of spring
nothing.
ANSWER : : ratio of coil diameter to wire diameter
16.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
102 d
124 d
138 d
151 d
168 d.
ANSWER : : 168 d.
17.The shearing stresses in the inner face as compared to outer face of the wire in a heavy close coiled spring is
larger
smaller
equal
larger/smaller depending on diameter of spring coil
unpredictable.
ANSWER : : larger
18.Applications in which stresses are encountered in one direction only uses following type of threads
metric
buttress
acme
square
BSW.
ANSWER : : buttress
19.If threads on a bolt are left hand, threads on nut will be
right hand with same pitch
left hand with same pitch
could be left or right hand
right hand with fine pitch
left hand with fine pitch.
ANSWER : : left hand with same pitch
20.Which of the following pipe joints would be suitable for pipes carrying steam
flanged
threaded
bell and spigot
expansion
compression.
ANSWER : : expansion
21.Split nut is a locking device in which
one smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
a slot is cut partly in middle of nut and then slot reduced by tightening screw
a hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed on the bolt causing a tight grip
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
none of the above.
ANSWER : : a slot is cut partly in middle of nut and then slot reduced by tightening screw
22.A bench vice has following type of threads
metric
square
buttress
acme
BSW.
ANSWER : : acme
23.For tight leakage joints, following type of thread is best suited
metric
buttress
square
acme
NPT (national pipe threads).
ANSWER : : NPT (national pipe threads).
24.Form coefficient of spring is
ratio of coil diameter to wire diameter
load required to produce unit deflection
its capability of storing energy
concerned With strength of wire of spring
nothing
ANSWER : : its capability of storing energy
25.Gear box is used
to produce torque
for speed reduction
to obtain variable speeds
to increase efficiency of system
to damp out vibrations.
ANSWER : : to obtain variable speeds
26.Basic hole is one
whose upper deviation is zero
whose lower deviation is zero
whose lower as well as upper deviations are zero
does not exist
none of the above.
ANSWER : : whose lower deviation is zero
27.The rated life of a bearing varies
directly as load
inversely as square of load
inversely as cube of load
inversely as fourth power of load
none of the above.
ANSWER : : inversely as cube of load
28.Aircraft body is usually fabricated by
welding
precasting
rivetting
casting
unconventional methods.
ANSWER : : rivetting
29.When two springs are in series (having stiffness K), the equivalent stiffness will be
K
K/2
2K
KIA
UK.
ANSWER : : K/2
30.In composite or reverse laid ropes
direction of twist of wires in strands is opposite to the direction of twist of strands
direction of twist of wires and strands are same
wires in two adjacent strands are twisted in opposite direction
wires are not twisted
none of the above.
ANSWER : : wires in two adjacent strands are twisted in opposite direction
31.I.S. specifies following total number of grades of tolerances
18
16
20
22
14.
ANSWER : : 18
32.In oiliness bearings
the oil film pressure is generated only by the rotation of the journal
the oil film is maintained by supplying oil under pressure
do not require external supply of lubricant
grease required to be applied after some intervals
none of the above.
ANSWER : : do not require external supply of lubricant
33.In hydrodynamic bearings
the oil film pressure is generated only by the rotation of the journal
the oil film is maintained by supplying oil under pressure
do not require external supply of lubricant
grease is used for lubrication
none of the above.
ANSWER : : the oil film pressure is generated only by the rotation of the journal
34.In hydrostatic bearings
the Oil film pressure is generated only by the rotation of the journal
the oil film is maintained by supplying oil under pressure
do not require external supply of lubricant
grease is used for lubrication
none of the above.
ANSWER : : the oil film is maintained by supplying oil under pressure
35.The usual clearance provided in hydrodynamic bearing per mm of diameter of shaft is
0.01 micron
0.1 micron
1 micron
10 microns
25 microns.
ANSWER : : 1 micron
36.If shearing stress in nut is half the tensile stress in a bolt, then nut length should be equal to
diameter of bolt
0.75 x diameter of bolt
1.25 x diameter of bolt
1.5 x diameter of bolt
0.5 x diameter of bolt.
ANSWER : : diameter of bolt
37.Whether any core is required in wireropes
yes
no
sometimes
rarely
very often.
ANSWER : : yes
38.In standard taper roller bearings, the angle of taper of outer raceway is
5�
8�
15�
25�
40�.
ANSWER : : 25�
39.Oil in journal bearing should be applied at the point where load is
nil or lightest
maximum
average
any one of the above
unpredictable.
ANSWER : : nil or lightest
40.Three different weights fall from a certain height under vacuum. They will take
same time to reach earth
times proportional to weight to reach earth
times inversely proportional to weight to reach earth
unpredictable
none of the above.
ANSWER : : same time to reach earth
41.Antifriction bearings are
sleeve bearings
hydrodynamic bearings
thin lubricated bearings
ball and roller bearings
none of the above.
ANSWER : : none of the above.
42.If two springs are in parallel then their overall stiffness will be
half
same
double
unpredictable
none of the above.
ANSWER : : double
43.If a spring is cut down into two springs, the stiffness of cut springs will be
half
same
double
unpredictable
none of the above.
ANSWER : : double
44.When a close coiled helical spring is compressed, its wire is subjected to
tension
shear
compression
all of the above
none of the above.
ANSWER : : tension
45.In V-belt drive, belt touches
at bottom
at sides only
both at bottom and sides
could touch anywhere
none of the above.
ANSWER : : at sides only
46.Belt slip may occur due to
heavy load
loose belt
driving pulley too small
all of the above
none of the above.
ANSWER : : all of the above
47.In cross or regular lay ropes
direction of twist of wires in strands is opposite to the direction of twist of strands
direction of twist of wires and strands are same
wires in two adjacent strands are twisted in opposite direction
wires are not twisted
none of the above.
ANSWER : : direction of twist of wires in strands is opposite to the direction of twist of strands
48.Basic shaft is one
whose upper deviation is zero
whose lower deviation is zero
whose lower as well as upper deviations are zero
does not exist
none of the above.
ANSWER : : whose upper deviation is zero
49.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
ZN/p
p/ZN
Z/pN
N/Zp
Zp/N.
ANSWER : : ZN/p
50.Allen bolts are
self locking bolts
designed for shock load
used in aircraft application
provided with hexagonal depression in head
uniform strength bolts.
ANSWER : : provided with hexagonal depression in head
51.The resultant axial load on a bolt depends on
initial tension
external load applied
relative elastic yielding (springiness) of the bolt and the connected member
(a) and (b) above
(a), (b) and (c) above.
ANSWER : : (a), (b) and (c) above.
52.The connecting rod bolts are tightened up so that tightening stress
is just sufficient to hold parts together
approaches yield point
is 50% of yield point
is about yield point divided by safety factor
none of the above.
ANSWER : : approaches yield point
54.When a bolt is subjected to shock loading, the resilience of the bolt should be considered in order to prevent breakage at
shank
head
in the middle
at the thread
anywhere in the bolt.
ANSWER : : at the thread
55.The connecting rod bolts are tightened up with initial tension greater than the external load so that
joint may not open up
bolts are weakest elements
the resultant load on the bolt would not be affected by the external cyclic load
bolts will not loosen during service
none of the above.
ANSWER : : the resultant load on the bolt would not be affected by the external cyclic load
56.If an application calls for stresses on screw threads in one direction only, then the following type of thread would be best suited
square
acme
buttress
BSW
metric.
ANSWER : : buttress
57.The shock absorbing capacity of a bolt can be increased by
tightening it properly
increasing shank diameter
grinding the shank
using washer
making shank diameter equal to core diameter of thread.
ANSWER : : making shank diameter equal to core diameter of thread.