Creep in belt is due to
Material of the belt
Material of the pulley
Uneven extensions and contractions due to varying tension
All of the above
Correct Answer :
C. Uneven extensions and contractions due to varying tension
Related Questions
Two rigid plates are clamped by means of bolt and nut with an initial force F. After tightening, a separating force P (P < F) is applied to the lower plate, which in turn acts on the nut. The tension in the both after this is
F + P
F P
P
F
Applications in which stresses are encountered in one direction only uses following type of threads
Metric
Buttress
Acme
Square
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
Spring stiffness is
Ratio of coil diameter to wire diameter
Load required to produce unit deflection
Its capability of storing energy
Its ability to absorb shocks
Oil in journal bearing should be applied at the point where load is
Nil or lightest
Maximum
Average
Any one of the above
Which of the following material has the maximum ductility?
Copper
Mild steel
Aluminium
Zinc
The initial tension (in newtons) in a bolt used for making a fluid tight joint like steam engine cover joints, is calculated by the relation (where d = Nominal diameter of bolt in mm)
1420 d
1680 d
2080 d
2840 d
The power transmitted by belt drive depends upon
Belt velocity
Initial belt tension
Arc of contact
All of the above
The velocity factor for very accurately cut and ground metallic gears operating at velocities upto __________ are equal to 6/(6 + v).
10 m/s
12.5 m/s
15 m/s
20 m/s
When the bearing is subjected to large fluctuations of load and heavy impacts, the bearing characteristic number should be _________ the bearing modulus.
10 times
5 times
15 times
20 times
The resultant axial load on a bolt depends on
Initial tension
External load applied
Relative elastic yielding (springness) of the bolt and the connected member
All of the above
Oldham coupling is used to connect two shafts
Which are perfectly aligned
Which are not in exact alignment
Which have lateral misalignment
Whose axes intersect at a small angle
A triple riveted butt joint with double straps of unequal width is to be designed for a boiler shell. The pitch of the rivets in the outer row is double the pitch in the inner row and zigzag riveting is proposed. Which of the following statement is correct?
There are four rivets per pitch length, all in double shear
There are four rivets per pitch length, out of which two are in single shear and two are in double shear
There are five rivets per pitch length, all in double shear
There are five rivets per pitch length, out of which four are in double shear and one is in single shear
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
When an open coiled helical compression spring is subjected to an axial compressive load, the stress induced in the wire is
Tensile stress
Compressive stress
Shear stress
Bending stress
Two helical springs of the same material and of equal circular crosssection, length and number of turns, but having radii 80 mm and 40 mm, kept concentrically (smaller radius spring within the larger radius spring), are compressed between two parallel planes with a load W. The inner spring will carry a load equal to
W/2
2W/3
W/9
8W/9
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 stress induced in the belt is,
Tensile stress
Compressive stress
Direct shear stress
Torsional shear stress
The application of third type levers is found in
A pair of tongs
Hand wheel of a punching press
Lever of a loaded safety valve
Handle of a hand pump
Shear stress theory is applicable for
Ductile materials
Brittle materials
Elastic materials
All of the above
A tap 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
Has pointed threads
The acme threads are usually found on
Spindles of bench vices
Railway carriage couplings
Feed mechanism of machine tools
Screw cutting lathes
For a shaft diameter of 100 mm, the number of bolts in a flange coupling should be
4
6
8
10
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
124 d
138 d
151 d
168 d
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
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
The helix angle for double helical gears may be made up to
45°
60°
75°
90°
The material used for brake lining should have __________ coefficient of friction.
Low
High
Moderate
None of these
Lewis form factor for 14 ½° composite and full depth involute system is (where T = Number of teeth)
0.124 - (0.684/T)
0.154 - (0.912/T)
0.175 - (0.841/T)
None of these
The ratio of pitch circle diameter in millimetres to the number of teeth, is called
Circular pitch
Diametral pitch
Module
None of these