A bolt is designed on the basis of __________ with a large factor of safety.
-
direct tensile stress -
direct compressive stress -
direct bending stress -
direct shear stress
In order to ensure self locking in a screw jack, it is essential that helix angle is __________ friction angle.
-
larger than -
smaller than -
equal to
When the frictional force helps to apply the brake, then the brake is said to be self-energizing brake.
-
Correct -
Incorrect
The temperature at which the new grains are formed in the metal is known as
-
lower critical temperature -
upper critical temperature -
recrystallisation temperature -
none of these
Multiple threads are used to secure
-
low efficiency -
high efficiency -
high load lifting capacity -
high mechanical advantage
The working of metals above the recrystallisation temperature is known as hot working.
-
True -
False
When the pulley or other mating piece is required to slide along the shaft, a __________ sunk key is used.
-
rectangular -
square -
parallel
Deep groove ball bearings are used for
-
heavy thrust load only -
small angular displacement of shafts -
radial load at high speed -
combined thrust and radial loads at high speed
The fatigue limit of a material is greatly decreased by poor surface conditions.
-
Agree -
Disagree
In a flange coupling, the bolts are subjected to
-
tensile stress -
compressive stress -
shear stress -
none of these
In a steam engine, the piston rod is usually connected to the crosshead by means of a
-
knuckle joint -
cotter joint -
oldham coupling -
universal joint
The contact ratio for gears is
-
zero -
less than one -
greater than one -
none of these
The shear modulus of resilience is proportional to
-
shear stress -
(shear stress)2 -
(shear stress)3 -
(shear stress)4
The value of Lewis form factor used in design of gears is
-
dependent on number of teeth of a gear -
dependent on system of teeth -
independent of size of teeth -
all of these
The ratio of number of teeth to the pitch circle diameter in millimetres is called circular pitch.
-
Agree -
Disagree
The bending moment M and a torque T is applied on a solid circular shaft. If the maximum bending stress equals to maximum shear stress developed, then M is equal to
-
T/2 -
T -
2 T -
4 T
The pressure angle of a cam is the angle between the direction of the follower motion and a normal to the pitch curve.
-
Correct -
Incorrect
The fatigue stress concentration factor is defined as
-
the ratio of endurance limit with stress concentration to the endurance limit without stress concentration -
the ratio of endurance limit without stress concentration to the endurance limit with stress concentration -
the product of the endurance limits with and without stress concentration -
all of the above
The radial distance from the top of a tooth to the bottom of a tooth is called clearance
-
True -
False
Lewis equation is applied
-
only to the pinion -
only to the gear -
to stronger of the pinion or gear -
to weaker of the pinion or gear
The material commonly used for machine tool bodies is
-
mild steel -
aluminium -
brass -
cast iron
The ratio of number of teeth to the pitch circle diameter in millimetres is called circular pitch.
-
Agree -
Disagree
A feather key is generally
-
loose in shaft and tight in hub -
tight in shaft and loose in hub -
tight in both shaft and hub -
loose in both shaft and hub
In a sawn nut, a slot is cut about half way through the nut and a small screw is tightened between the nut and the bolt in order to produce more friction.
-
Agree -
Disagree
The maximum bending stress in a curved beam having symmetrical section always occur at the
-
centroidal axis -
neutral axis -
inside fibre -
outside fibre
Which of the following statement is correct regarding power screws?
-
The efficiency of a self locking screw can not be more than 50% -
The efficiency of Acme (trapezoidal) thread is less than that of a square thread -
If the friction angle is less than the helix angle of the screw, then the efficiency will be more than 50% -
(A) and (B) Only
In case of thick cylinders, the tangential stress across the thickness of cylinder is
-
maximum at the outer surface and minimum at the inner surface -
maximum at the inner surface and minimum at the outer surface -
maximum at the inner surface and zero at the outer surface -
maximum at the outer surface and zero at the inner surface
The washer is generally specified by its
-
outer diameter -
hole diameter -
thickness -
mean diameter
For longitudinal joint in boilers, the type of joint used is
-
butt joint with single cover plate -
butt joint with double cover plate -
lap joint with one ring overlapping the other -
any one of the above
A fast and loose pulley drive is used when
-
shafts are arranged parallel and rotate in the opposite directions -
shafts are arranged parallel and rotate in the same directions -
shafts are arranged at right angles and rotate in one definite direction -
driven shaft is to be started or stopped whenever desired without interferring with the driving shaft
A compound cylinder with inner radiusmm and outer radiusmm is made by shrinking one cylinder on to the other cylinder, The junction radius ismm and the junction pressure is 1.1 N/mm2. The maximum hoop stress developed in the inner cylinder is
-
3.6 N/mm2 compression -
3.6 N/mm2 tension -
7.2 N/mm2 compression -
7.2 N/mm2 tension
A key made from a cylindrical disc having segmental cross-section, is known as
-
feather key -
gib-head key -
wood ruff key -
flat saddle key
A tap bolt has
-
threads for the nut at one end and head at the other end -
head at one end and the other end fits into a tapped hole of one of the parts to be fastened -
threads at both ends -
pointed threads
If the tearing efficiency of a riveted joint is 50%, then the ratio of diameter of rivet to the pitch is
-
0.20 -
0.30 -
0.50 -
0.70
In radial bearings, the load acts __________ to the axis of rotation.
-
parallel -
perpendicular
A hollow shaft will transmit a __________ torque than a solid shaft of the same mass and same material.
-
smaller -
greater
If T is the actual number of teeth on a helical gear and φ is the helix angle for the teeth, then formative number of teeth is written as
-
T sec3 φ -
T sec2 φ -
T/sec3 φ -
T cosec φ
In helical gears, the distance between similar faces of adjacent teeth along a helix on the pitch cylinders normal to the teeth, is called
-
normal pitch -
axial pitch -
diametral pitch -
module
The taper on key is given on
-
bottom side only -
top side only -
on both sides -
any side
Which of the following statement is wrong for a connecting rod ?
-
The connecting rod will be equally strong in buckling about X-axis and Y-axis, if Ixx = 4 Iyy -
If Ixx > 4Iyy., the buckling will occur about Y-axis -
If Ixx < 4Iyy., the buckling will occur about X-axis -
The most suitable section for the connecting rod is T-section
A bolt has
-
threads for the nut at one end and head at the other end -
head at one end and the other end fits into a tapped hole of one of the parts to be fastened -
threads at both ends -
pointed threads
If T is the actual number of teeth on a helical gear and φ is the helix angle for the teeth, then formative number of teeth is written as
-
T sec3 φ -
T sec2 φ -
T/sec3 φ -
T cosec φ
When percentage of carbon in steel is increased, the ductility of steel decreases.
-
Correct -
Incorrect
A cotter joint is used to transmit
-
combined axial and twisting loads -
axial tensile load only -
axial compressive load only -
axial tensile or compressive loads
Which of the following screw thread is adopted for power transmission in either direction?
-
Acme threads -
Square threads -
Buttress threads -
Multiple threads
A connecting rod subjected to an axial load may buckle in the plane of motion of the connecting rod.
-
Correct -
Incorrect
The helix angle for double helical gears may be made up to
-
45° -
60° -
75° -
90°
According to I.B.R., when the thickness of the boiler shell (t) is less than 8 mm, then the diameter of the rivet hole (d) is obtained by
-
equating tearing resistance of the plate to the shearing resistance of the rivets -
equating tearing resistance of the plate to the crushing resistance of the rivets -
equating shearing resistance to the crushing resistance of the rivets -
none of the above
The ratio of circumferential stress to longitudinal stress in a thin cylinder subjected to an internal pressure is
-
1/2 -
1 -
2 -
4
When a load W is applied suddenly on a bar of cross-sectional area A, the stress induced in the bar will be
