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
Correct Answer :
A. Prevent the belt from running off the pulley
Related Questions
The elasticity is the property of a material which enables it to
Regains its original shape after deformation when the external forces are removed
Draw into wires by the application of a tensile force
Resists fracture due to high impact loads
Retain deformation produced under load permanently
Yield point in fatigue loading as compared to static loading is
Same
Higher
Lower
Depends on other factors
The toughness of a material _________ when it is heated
Does not change
Increases
Decreases
None of the Above
The condition for maximum power transmission is that the maximum tension in the flat belt should be equal to
3 Pc
Pc
Pc/3
2 Pc Where, Pc = tension in belt due to centrifugal force
A stud
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
A bench vice has following type of threads
Metric
Square
Buttress
Acme
The permissible stress in the fillet weld is 100 N/mm². The fillet weld has equal leg lengths of 15 mm each. The allowable shearing load on the weldment per cm length of the weld is
7.5 kN
10.6 kN
15 kN
22.5 kN
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
In an oil lubricated journal bearing, the coefficient of friction between the journal and the bearing
Remains constant at all speeds
Is minimum at zero speed and increases monotonically with increase in speed
Is maximum at zero speed and decreases monotonically with increase in speed
Becomes minimum at an optimum speed and then increases with further increase in speed
The stiffness of a closely coiled helical spring subjected to an axial load W is equal to (where G = Modulus of rigidity, and n = Number of active coils)
Gd⁴/ 8D3n
Gd3/ 8D3n
Gd⁴/ 4D3n
Gd⁴/ 8D²n
When two springs are in series (having stiffness K), the equivalent stiffness will be
K
K/2
2K
K/4
The suitable material for belt used in flour mill is
Leather
Rubber
Canvas or cotton duck
Balata gum
According to Indian standard specifications, 100 H6/g5 means that the
Basic size is 100 mm
Actual size is 100 mm
Difference between the actual size and basic size is 100 mm
None of the above
Fibrous fracture occurs in
Ductile material
Brittle material
Elastic material
Hard material
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
The notch sensitivity q is expressed in terms of fatigue stress concentration factor Kf and theoretical stress concentration factor Kt as
(Kf + 1)/ (Kt + 1)
(Kf - 1)/ (Kt - 1)
(Kt + 1)/ (Kf + 1)
(Kt - 1)/ (Kf - 1)
When a close coiled helical spring is compressed, its wire is subjected to
Tension
Shear
Compression
All of the above
In a butt welded joint, the size of weld is __________ the throat of weld.
0.5 times
Equal to
2 times
Double
The rolling contact bearings as compared to sliding contact bearings have
Low starting and low running friction except at very high speeds
Accuracy of shaft alignment
Small overall dimensions
All of the above
A connecting rod should be
Strong in buckling about X-axis
Strong in buckling about Y-axis
Equally strong in buckling about X-axis and Y-axis
Any one of the above
A transmission shaft includes
Over head shaft
Counter shaft
Line shaft
All of these
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
A chain drive transmits __________ power as compared to belt drive.
More
Less
Same
None of these
In radial bearings, the load acts __________ to the axis of rotation.
Parallel
Perpendicular
Both A and B
None of these
A sliding bearing which operates without any lubricant present, is called
Zero film bearing
Boundary lubricated bearing
Hydrodynamic lubricated bearing
Hydrostatic lubricated bearing
For maximum power, the velocity of the belt will be
√(T/m)
√(T/2m)
√(T/3m)
None of these
Stress concentration is caused due to
Variation in properties of material from point to point in a member
Pitting at points or areas at which loads on a member are applied
Abrupt change of section
All of the above
Oil in journal bearing should be applied at the point where load is
Nil or lightest
Maximum
Average
Any one of the above
The size of a gear is usually specified by
Pressure angle
Pitch circle diameter
Circular pitch
Diametral pitch
An imaginary circle which by pure rolling action gives the same motion as the actual gear, is called
Addendum circle
Dedendum circle
Pitch circle
Clearance circle