What will be efficiency of the screw in case of raising the load when coefficient of friction is 0.1553 and tangent of helix angle is 0.0813?

A)
34%
B)
43%
C)
45%
D)
54%

Correct Answer : Option (A) :   34%

Explanation : Efficiency= tanἀ(1-0.1553 x tan ἀ)/(0.1553+tanἀ).

Recently Updated in Machine Design Questions
Which type of rope drum is preferred?
A)
Drums with helical grooves
B)
Plain cylindrical drums
C)
Both are equally preferred
D)
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?
A)
Higher cost of small sheaves
B)
Increasingly centrifugal force in large sheaves
C)
Preferring centrifugal force reduction even for more money
D)
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
A)
Tensile Stress
B)
Bending Stress
C)
Both bending and tensile stress
D)
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.

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