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Current Affairs January 2024

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4

The arms of the pulleys for flat belt drive have

A. Elliptical cross-section

B. Major axis in plane of rotation

C. Major axis twice the minor axis

D. All the three characteristics

Correct Answer :

D. All the three characteristics


Related Questions

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4

According to I.B.R., when the thickness of boiler shell (t) is greater than 8 mm, then the diameter of rivet hole (d) is obtained by

A. Equating tearing resistance of the plate to the shearing resistance of the rivets

B. Equating tearing resistance of the plate to the crushing resistance of the rivets

C. Equating shearing resistance to the crushing resistance of the rivets

D. None of the above

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4

If shearing stress in nut is half the tensile stress in a bolt, then nut length should be equal to

A. Diameter of bolt

B. 0.75 × diameter of bolt

C. 1.25 × diameter of bolt

D. 1.5 × diameter of bolt

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4

A compound cylinder with inner radius 50 mm and outer radius 70 mm is made by shrinking one cylinder on to the other cylinder, the junction radius is 60 mm and the junction pressure is 1.1 N/mm². The maximum hoop stress developed in the inner cylinder is

A. 3.6 N/mm² compression

B. 3.6 N/mm² tension

C. 7.2 N/mm² compression

D. 7.2 N/mm² tension

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4

Castle nut is a locking device in which

A. One smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming

B. A slot is cut partly is middle of nut and then slot reduced by tightening a screw

C. 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

D. Through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter pin spitted and bent in reverse direction at other end

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4

If a bearing is designated by the number 305, it means that the bearing is of

A. Medium series whose bore is 5 mm

B. Medium series whose bore is 25 mm

C. Light series whose bore is 25 mm

D. Light series whose bore is 5 mm

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4

When the bearing is subjected to large fluctuations of load and heavy impacts, the bearing characteristic number should be _________ the bearing modulus.

A. 10 times

B. 5 times

C. 15 times

D. 20 times

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4

In designing a sleeve coupling, length of the sleeve is taken as (where d = Diameter of the shaft)

A. d + 17 mm

B. 2d + 13 mm

C. 2d + 20 mm

D. 3.5d

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4

Oil in journal bearing should be applied at the point where load is

A. Nil or lightest

B. Maximum

C. Average

D. Any one of the above

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4

For a shoe brake, the equivalent coefficient of friction is equal to (where μ = Actual coefficient of friction, and θ = Semi-block angle)

A. 2μ sinθ/(θ + sinθ)

B. μ sinθ/(2θ + sin 2θ)

C. 4μ sinθ/(θ + sinθ)

D. 4μ sinθ/(2θ + sin 2θ)

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4

In second type of levers,

A. Load is in between the fulcrum and effort

B. Effort is in between the fulcrum and load

C. Fulcrum is in between the load and effort

D. None of these

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4

According to I.B.R., the factor of safety of riveted joint should not be less than

A. 1

B. 2

C. 3

D. 4

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4

In a marine flange coupling, the thickness of flange is taken as

A. d/2

B. d/3

C. 3d/4

D. d/4

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4

Which one of the following is a positive drive?

A. V-belt drive

B. Rope drive

C. Crossed flat belt drive

D. Chain drive

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4

The shear stress at a point in a shaft subjected to a torque is

A. Directly proportional to the polar moment of inertia and to the distance of the point from the axis

B. Directly proportional to the applied torque and inversely proportional to the polar moment of inertia

C. Directly proportional to the applied torque and the polar moment of inertia

D. Inversely proportional to the applied torque and the polar moment of inertia

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4

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

A. 124 d

B. 138 d

C. 151 d

D. 168 d

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4

The cold working of metals is carried out __________ the recrystallisation temperature.

A. Above

B. Below

C. At

D. None of these

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4

In worm gears, the pressure angle is ________ the angle between two inclined faces in axial plane.

A. Half

B. Twice

C. Thrice

D. None of these

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4

A screw is said to be a self locking screw, if its efficiency is

A. Less than 50 %

B. More than 50 %

C. Equal to 50 %

D. None of these

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4

Idler pulley is used for

A. Increasing velocity ratio

B. For applying tension

C. Changing the direction of motion of belt

D. All of these

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4

Which of the following statement is correct?

A. The stress concentration in static loading is more serious in ductile materials and less serious in brittle materials

B. The stress concentration in static loading is more serious in brittle materials and less serious in ductile materials

C. The toughness of a material increases when it is heated

D. The shear stress in a beam varies from zero at the neutral surface and maximum at the outer fibres

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4

The power transmitted by the belt drive can be increased by

A. Increasing the initial tension in the belt

B. Dressing the belt to increase the coefficient of friction

C. Increasing wrap angle by using idler pulley

D. All of the above methods

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4

Crushing resistance required to crush the rivet per pitch length is

A. p.d.σc

B. p.t.σc

C. n.d.t.σc

D. (p - d) t.σc

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4

In radial bearings, the load acts __________ to the axis of rotation.

A. Parallel

B. Perpendicular

C. Both A and B

D. None of these

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4

The centre to centre distance between two consecutive rivets in a row, is called

A. Margin

B. Pitch

C. Back pitch

D. Diagonal pitch

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4

Whether any core is required in wire ropes

A. Yes

B. No

C. Sometimes

D. Rarely

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4

The static tooth load should be __________ the dynamic load.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

The centrifugal tension in belts

A. Decreases the power transmitted

B. Increases the power transmitted

C. Increase the wrap angle

D. Increases the belt tension without increasing power transmission

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4

Basic shaft is one

A. Whose upper deviation is zero

B. Whose lower deviation is zero

C. Whose lower as well as upper deviations are zero

D. Does not exist

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4

When the screw in a mechanical screw jack rotates, the load kept on the top of it moves

A. Axially upwards

B. Axially downwards

C. Axially upwards or downwards

D. None of these

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4

A hollow saddle key is

A. A taper key which fits half in the key way of hub and half in the key way of shaft

B. A taper key which fits in a key way of the hub and is flat on the shaft

C. A taper key which fits in a key way of the hub and the bottom of the key is shaped to fit the curved surface of the shaft

D. Provided in pairs at right angles and each key is to withstand torsion in one direction only