The included angle in unified of American National threads is
60°
55°
47°
29°
Correct Answer :
A. 60°
Related Questions
When bevel gears connect two shafts whose axes intersect at an angle greater than a right angle and one of the bevel gears has a pitch angle of 90°, then they are known as
Crown bevel gears
Angular bevel gears
Mitre gears
Internal bevel gears
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
The maximum efficiency of a square threaded screw is
(1 - sinφ)/ (1 + sinφ)
(1 + sinφ)/ (1 - sinφ)
(1 - sinφ)/ (1 + cosφ)
(1 + cosφ)/ (1 - sinφ)
When a hole of diameter d is punched in a metal of thickness 't', then the force required to punch a hole is equal to (where τu = Ultimate shear strength of the material of the plate)
d.t.τu
πd.t.τu
π/4 × d².τu
π/4 × d² × t.τu
When a circular beam of diameter d is subjected to a shear force F, the maximum shear stress induced will be
4F/ πd²
6F/ πd²
8F/ πd²
16F/ 3πd²
A type of brake commonly used in motor cars is a
Shoe brake
Band and block brake
Band brake
Internal expanding brake
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)
A single strap butt joint is always in __________ shear.
Single
Double
Triple share
None of these
The gears are termed as medium velocity gears, if their peripheral velocity is
1-3 m/s
3-15 m/s
15-30 m/s
30-50 m/s
The expansion joint is mostly used for pipes which carry steam at __________ pressures.
Low
High
Medium
None of these
Whether any core is required in wire ropes
Yes
No
Sometimes
Rarely
In second type of levers,
Load is in between the fulcrum and effort
Effort is in between the fulcrum and load
Fulcrum is in between the load and effort
None of these
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
An elastic bar is fixed at the upper end and loaded at the lower end by a falling weight. The shock load produced can be reduced by
Increasing the length of bar
Decreasing the cross-sectional area of the bar
Decreasing the modulus of elasticity of the bar
All of the above
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
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 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
Decreasing the cross-section area of bar
Increasing the cross-section area of bar
Remain unaffected with cross-section area
Would depend upon other factors
A screw is said to be a self locking screw, if its efficiency is
Less than 50 %
More than 50 %
Equal to 50 %
None of these
Allen bolts are
Self locking bolts
Designed for shock load
Used in aircraft application
Provided with hexagonal depression in head
When the fulcrum is in between the load and effort, the lever is said to be of
First type
Second type
Third type
Any one of these
The cross-section of the arm of a bell crank lever is
Rectangular
Elliptical
I-section
Any one of these
The included angle for the V-belt is usually
10°-20°
30°-40°
40°-60°
60°-80°
The suitable material for belt used in flour mill is
Leather
Rubber
Canvas or cotton duck
Balata gum
Rivets are generally specified by
Thickness of plates to be riveted
Length of rivet
Diameter of head
Nominal diameter
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 a flange coupling, the bolts are subjected to
Tensile stress
Compressive stress
Shear stress
None of these
When a bolt is subjected to shock loading, the resilience of the bolt should be considered in order to prevent breakage at the
Thread
Middle
Shank
Head
In a marine flange coupling, the thickness of flange is taken as
d/2
d/3
3d/4
d/4
The objective of crowning of the flat pulleys of belt drive is to
Prevent the belt from running off the pulley
Increase the power transmission capacity
Increase the belt velocity
Prevent the belt joint from damaging the belt surface
A bolt
Has a head on one end and a nut fitted to the other
Has head at one end and other end fits into a tapped hole in the other part to be joined
Has both the ends threaded
Is provided with pointed threads