If for a trapezoidal thread, angle of thread is 15â€™ then what will be the replacement of the coefficient of friction which is 0.15.

Mechanical Engineering : Machine Design - Quiz(MCQ)

0.1335

0.1776

0.1553

0.1667

Correct Answer : Option (C) : 0.1553

Explanation : f=0.15 x sec 15’

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Which type of rope drum is preferred?

Drums with helical grooves

Plain cylindrical drums

Both are equally preferred

None of the above

Correct Answer : Drums with helical grooves

Explanation : They have more bearing surface of the drum and prevent friction between adjacent turns of the rope.

Small sheaves are preferred over large sheaves on what parameters?

Higher cost of small sheaves

Increasingly centrifugal force in large sheaves

Preferring centrifugal force reduction even for more money

None of the above

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The wire rope is subjected to

Tensile Stress

Bending Stress

Both bending and tensile stress

None of the above

Correct Answer : Both bending and tensile stress

Explanation : There is direct tensile stress due to load being raised as well as bending stress.