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)
Correct Answer :
A. 0.75/ (0.75 + √v)
Related Questions
The resultant axial load on a bolt depends upon
External load applied
Initial tension due to tightening of the bolt
Relative elastic yielding of the bolt and the connected members
All of the above
In a full journal bearing, the angle of contact of the bearing with the journal is
120°
180°
270°
360°
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
For applications involving high stresses in one direction only the following type of thread would be best suited
ISO metric thread
Acme thread
Square thread
Buttress thread
According to maximum shear stress theory, the maximum shear stress in the shaft is
(1/2) × √(σ² + 4τ²)
√(σ² + 4τ²)
(1/2) × [σ + √(σ² + 4τ²)]
σ + √(σ² + 4τ²)
A coupling used to connect two perfectly aligned shafts, is
Muff coupling
Compression coupling
Flange coupling
All of these
A transmission shaft includes
Over head shaft
Counter shaft
Line shaft
All of these
When the bolt is very yielding as compared to the connected members, then the resultant load on the bolt will be equal to the
Initial tension
External load applied
Sum of the initial tension and external load applied
Initial tension or external load, whichever is greater
In a marine flange coupling, the thickness of flange is taken as
d/2
d/3
3d/4
d/4
If the centre distance of the mating gears having involute teeth is increased, then the pressure angle
Increases
Decreases
Remains unchanged
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
Stress concentration factor is defined as the ratio of
Maximum stress to the endurance limit
Nominal stress to the endurance limit
Maximum stress to the nominal stress
Nominal stress to the maximum stress
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
When compared to the rod of the same diameter and material, a wire rope
Is less flexible
Has a much smaller load carrying capacity
Does not provide much warning before failure
Provides much greater time for remedial action before failure
The cracks in helical springs used in railway carriages usually start on the inner side of the coil because of the fact that
It is subjected to a higher cyclic loading than the outer side
It is subjected to a higher stress than the outer side
It is more stretched than the outer side during the manufacturing process
It has a lower curvature than the outer side
Stress concentration is caused due to
Variations in load acting on a member
Variations in properties of materials in a member
Abrupt change of cross-section
All of these
In a flange coupling, the flanges are coupled together by means of
Bolts and nuts
Studs
Headless taper bolts
None of these
Which of the following is a permanent fastening?
Bolts
Keys
Cotters
Rivets
The helix angle for double helical gears may be made up to
45°
60°
75°
90°
The process extensively used for making bolts and nuts is
Hot piercing
Extrusion
Cold peening
Cold heading
The property of a bearing material which has the ability to accomodate shaft deflections and bearing inaccuracies by plastic deformation without excessive wear and heating, is known as
Bondability
Embeddability
Comformability
Fatigue strength
The velocity of sliding ________ the distance of the point of contact from the pitch point.
Is directly proportional to
Is inversely proportional to
Is equal to cos φ multiplied by
Does not depend upon
The ratio of endurance limit in shear to the endurance limit in flexure is
0.33
0.4
0.5
0.55
The spring mostly used in gramophones is
Helical spring
Conical spring
Flat spiral spring
Volute spring
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
The distribution of the forces along the length of key fitted in a shaft
Varies linearly
Is uniform throughout
Varies exponentially, being more near the torque-input end
Varies exponentially, being less near the torque-input end
In a flat belt drive, if the slip between the driver and belt is 1 %, between the belt and follower is 3% and driver and follower pulley diameters are equal, then velocity ratio of the drive will be
0.96
0.97
0.98
0.99
Which is positive drive?
Flat belt drive
V-belt drive
Crossed belt drive
Timing belt
Pick up wrong statement. Fatigue strength can be increased by
Cold working
Shot peening
Grinding and lapping surface
Hot working
If T₁ and T₂ are the tensions on the tight and slack sides of the belt respectively, and Tc is the centrifugal tension, then initial tension in the belt is equal to
T₁ - T₂ + Tc
T₁ + T₂ + Tc
(T₁ - T₂ + Tc)/2
(T₁ + T₂ + Tc)/2