When a close coiled helical spring is compressed, its wire is subjected to
Tension
Shear
Compression
All of the above
Correct Answer :
A. Tension
Related Questions
The load cup of a screw jack is made separate from the head of the spindle to
Prevent the rotation of load being lifted
Enhance the load carrying capacity of the jack
Reduce the effort needed for lifting the working load
Reduce the value of frictional torque
In designing a connecting rod, it is considered like __________ for buckling about X-axis.
Both ends hinged
Both ends fixed
One end fixed and the other end hinged
One end fixed and the other end free
When two helical springs of equal lengths are arranged to form a cluster spring, then
Shear stress in each spring will be equal
Load taken by each spring will be half the total load
Only A is correct
Both A and B is correct
If the centre distance of the mating gears having involute teeth is varied within limits, the velocity ratio.
Increases
Decreases
Remains unchanged
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
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
Wire ropes as compared to cotton ropes
Are lighter in weight
Offer silent operation
Can withstand shock loads
All of these
In the calculation of induced shear stress in helical springs, the Wahl's stress factor is used to take care of
Combined effect of transverse shear stress and bending stress in the wire
Combined effect of bending stress and curvature of the wire
Combined effect of transverse shear stress and curvature of wire
Combined effect of torsional shear stress and transverse shear stress in the wire
In oilness 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
The velocity factor for precision metallic gears cut with high accuracy and operating at velocities upto 20 m/s is equal to
0.75/ (0.75 + √v)
3/ (3 + v)
4.5/ (4.5 + v)
6/ (6 + v)
A tapered key which fits in a key-way in the hub and is flat on the shaft, is known as
Woodruff key
Feather key
Flat saddle key
Gib head key
The valve rod in a steam engine is connected to an eccentric rod by
Cotter joint
Bolted joint
Knuckle joint
Universal coupling
The value of stress concentration factor depends upon
Material and geometry of the part
Geometry of the part
Material of the part
None of these
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
The ultimate strength of steel in tension in comparison to shear is in the ratio of
1 : 1
2 : 1
3 : 2
2 : 3
A metal pipe of 1 m diameter contains a fluid having a pressure of 1 N/mm². If the permissible tensile stress in the metal is 20 N/mm², then the thickness of the metal required for making the pipe will be
5 mm
10 mm
15 mm
25 mm
Which is correct statement? Stress concentration in static loading is
Very serious in brittle materials and less serious in ductile materials
Very serious in ductile materials and less serious in brittle materials
Equally serious in both types of materials
Seriousness would depend on other factors
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
None of these
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
A bolt of uniform strength can be developed by
Keeping the core diameter of threads equal to the diameter of unthreaded portion of the bolt
Keeping the core diameter smaller than the diameter of the unthreaded portion
Keeping the nominal diameter of threads equal to the diameter of unthreaded portion of the bolt
None of the above
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
Elastic nut is a locking device in which
One small 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 a screw
Hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is stewed 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 other end
If the size of a standard specimen for a fatigue testing machine is increased, the endurance limit for the material will
Have same value as that of standard specimen
Increase
Decrease
None of these
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
In nitrated parts, the origins of the fatigue cracks will occur at
Surface
Just below the surface
Within the core
None of the above
A V-belt designated as B 4430 LP has
4430 mm as diameter of small pulley
4430 mm as nominal pitch length
4430 mm as diameter of large pulley
4430 mm as centre distance between pulleys
The width of the pulley should be __________ width of the belt.
Equal to
Less than
Greater than
None of these
Residual stress in materials
Acts when external load is applied
Becomes zero when external load is removed
Is independent of external loads
Is always harmful
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
Which of the following material has the maximum ductility?
Copper
Mild steel
Aluminium
Zinc