The toughness of a material _________ when it is heated
Does not change
Increases
Decreases
None of the Above
Correct Answer :
C. Decreases
Related Questions
The helix angle for single helical gears ranges from
10° to 15°
15° to 20°
20° to 35°
35° to 50°
Cast iron pipes are mainly used
For conveying steam
In water and sewage systems
In pressure lubrication systems on prime movers
All of the above
In thrust bearings, the load acts
Along the axis of rotation
Parallel to the axis of rotation
Perpendicular to the axis of rotation
In any direction
The number of slots in a 25 mm castle nut is
8
4
2
6
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
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
According to Indian standard specifications, 100 H6/g5 means that
Tolerance grade for the hole is 6 and for the shaft is 5
Tolerance grade for the shaft is 6 and for the hole is 5
Tolerance grade for the shaft is 4 to 8 and for the hole is 3 to 7
Tolerance grade for the hole is 4 to 8 and for the shaft is 3 to 7
A column is known as a long column if the slenderness ratio is
40
50
70
100
A bolt of M 24 × 2 means that
The pitch of the thread is 24 mm and depth is 2 mm
Cross-sectional area of the threads is 24 mm²
The nominal diameter of bolt is 24 mm and pitch is 2 mm
The effective diameter of bolt is 24 mm and there are 2 threads per cm
The stretching in a belt can be controlled by __________ the stress in the belt.
Reducing
Increasing
Both A and B
None of these
For high speed engines, the cam follower should move with
Uniform velocity
Simple harmonic motion
Uniform acceleration and retardation
Cycloidal motion
A key capable of tilting in a recess milled out in a shaft is known as
Woodruff key
Feather key
Flat saddle key
Hollow saddle key
According to Indian standards, the diameter of rivet hole is made larger than the basic size of rivet by
0.5 mm upto rivet diameter of 24 mm
1 mm for rivet diameter from 27 mm to 36 mm
2 mm for rivet diameter from 39 mm to 48 mm
All of the above
The valve rod in a steam engine is connected to an eccentric rod by
Cotter joint
Bolted joint
Knuckle joint
Universal coupling
In skew bevel gearing, the axes of shafts are
Intersecting and the teeth are curved
Non-intersecting and nonparallel and the teeth are curved
Non-intersecting and non-parallel and the teeth are straight
None of the above
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
1 kN-m
2 kN-m
3 kN-m
4 kN-m
According to I.B.R., the efficiency of a double riveted butt joint with double cover straps of equal width should be
45 to 60 %
63 to 70 %
70 to 83 %
80 to 90 %
In the assembly of pulley, key and shaft
Pulley is made the weakest
Key is made the weakest
Key is made the strongest
All the three are designed for equal strength
The minimum number of teeth on the pinion which will mesh with any gear without interference for 20° full depth involute teeth will be
12
14
18
24
A shaft is subjected to a maximum bending stress of 80 N/mm² and maximum shearing stress equal to 30 N/mm² at a particular section. If the yield point in tension of the material is 280 N/mm² and the maximum shear stress theory of failure is used, then the factor of safety obtained will be
2.5
2.8
3.0
3.5
The crest diameter of a screw thread is same as
Major diameter
Minor diameter
Pitch diameter
Core diameter
For a shoe brake, the equivalent coefficient of friction is equal to (where μ = Actual coefficient of friction, and θ = Semi-block angle)
2μ sinθ/(θ + sinθ)
μ sinθ/(2θ + sin 2θ)
4μ sinθ/(θ + sinθ)
4μ sinθ/(2θ + sin 2θ)
In case of V-belt drive
The belt should touch the bottom of groove in the pulley
The belt should not touch the bottom of groove in the pulley
The belt should not touch the sides of groove in the pulley
None of the above
For tight leakage joints, following type of thread is best suited
Metric
Buttress
Square
NPT (national pipe threads)
A spring is used to
Measure forces
Apply forces
Store energy
All of these
In worm gears, the angle between the tangent to the pitch helix and an element of the cylinder, is known as
Helix angle
Pressure angle
Pitch lead angle
None of these
Soderberg relation is based on __________ of the material whereas all other failure relation for dynamic loading are based on ultimate strength of the material.
Elastic strength
Yield strength
Shear strength
None of these
The deflection of a cantilever beam under load W is 8. If its width is halved, then the deflection under load W will be
2/8
8/2
4/8
8/4
Slenderness ratio is the ratio of
Effective length of column to least radius of gyration of the column
Width of column to depth of column
Maximum size of column to minimum size of column
Effective length of column to width of column
If a shaft made from ductile material is subjected to combined bending and twisting moment, calculations based on which one of the following failure theories will give the most conservative value?
Maximum principal stress theory
Maximum shear stress theory
Maximum strain energy theory
Maximum distortion energy theory