Self-locking takes place when - Machine Design Quiz

Mechanical Engineering : Machine Design - Quiz(MCQ)

Self-locking takes place when

Coefficient of friction is lesser than or equal to the tangent of the helix angle

Coefficient of friction is equal to or greater than the tangent of the helix angle

None of the above

Correct Answer : Option (C) : Coefficient of friction is equal to or greater than the tangent of the helix angle

Explanation : Self locking takes place if load does not descend on its own and that is possible only in c condition.

Recently Updated in Machine Design Questions

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

Correct Answer : Increasingly centrifugal force in large sheaves

Explanation : Larger sheaves have higher centrifugal forces and higher cost because more material is used in their construction.

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.