Pick up wrong statement. Fatigue strength can be increased by
Cold working
Shot peening
Grinding and lapping surface
Hot working
Correct Answer :
D. Hot working
Related Questions
The steel pulleys are __________ in weight than cast iron pulleys of the same capacity.
Heavier
Lighter
Moderate
None of these
According to I.B.R., shearing resistance required to shear off the rivet per pitch length (in double shear) is (where n = Number of rivets per pitch length)
(π/4) d² × τ × n
1.875 × (π/4) d² × τ × n
2 × (π/4) d² × τ × n
3 × (π/4) d² × τ × n
Taper on the cotter and slot is provided
On both the sides
On one side only
On none of the sides
May be provided anywhere
Which of the following property is essential for spring materials?
Stiffness
Ductility
Resilience
Plasticity
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
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
If an application calls for stresses on screw threads in one direction only, then the following type of thread would be best suited
Square
Acme
Buttress
BSW
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
The bearings of heavy series have capacity ________ over the medium series.
20 to 30%
10 to 20%
30 to 40%
40 to 50%
In radial bearings, the load acts __________ to the axis of rotation.
Parallel
Perpendicular
Both A and B
None of these
The rolling contact bearings are known as
Thick lubricated bearings
Plastic bearings
Antifriction bearings
Thin lubricated bearings
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
In replacing the V-belts, a complete set of new belts is used instead of replacing a single damaged belt because
Belts are available in sets
Only one belt cannot be fitted with other used belts
The new belt will carry more than its share and result in short life
New and old belts will cause vibrations
Jam nut is a locking device in which
One smaller 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
A hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed 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 spitted and bent in reverse direction at other end
A self locking screw has
Fine threads
Course threads
Coefficient of friction is greater than tangent of load angle
Hole for inserting split pin
When a closely coiled helical spring is subjected to a couple about its axis, the stress induced in the wire material of the spring is
Bending stress only
A combination of torsional shear stress and bending
Direct shear stress only
A combination of bending stress and direct shear stress
In leaf springs, the longest leaf is known as
Master leaf
Lower leaf
Upper leaf
None of these
In a hydrodynamic lubricated bearing
There is a thick film of lubricant between the journal and the bearing
There is a thin film of lubricant between the journal and the bearing
The lubricant is forced between the journal and the bearing, by external pressure
There is no lubricant between the journal and the bearing
Multiple threads are used to secure
Low efficiency
High efficiency
High load lifting capacity
High mechanical advantage
The building up of worn and undersized parts, subjected to repeated loads by electroplating is
Best method
Extremely hazardous
Has no effect as regards fatigue strength
Cheapest method
The stretching in a belt can be controlled by __________ the stress in the belt.
Reducing
Increasing
Both A and B
None of these
The number of slots in a 25 mm castle nut is
8
6
4
2
In designing a key, it is assumed that the distribution of forces along the length of key
Varies linearly
Is uniform throughout
Varies exponentially, being more at the torque-input end
Varies exponentially, being less at the torque-input end
The maximum stress due to stress concentration in a bar having circular transverse hole, as compared to its static stress without hole will be
Same in both cases
2 times more
3 times more
4 times more
The acme threads are usually found on
Spindles of bench vices
Railway carriage couplings
Feed mechanism of machine tools
Screw cutting lathes
Split nut is a locking device in which
One smaller 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 screw
A hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed 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 the other end
The cold working of metals is carried out __________ the recrystallisation temperature.
Above
Below
At
None of these
In a partial journal bearing, the angle of contact of the bearing with the journal is
120°
180°
270°
360°
The shock absorbing capacity of a bolt may be increased by
Increasing its shank diameter
Decreasing its shank diameter
Tightening the bolt properly
Making the shank diameter equal to core diameter of thread
In most machine members, the damping capacity of the material should be
Low
Zero
High
Could be anything