The efficiency of a screw jack is maximum, when (where Î± = Helix angle, and Ï† = Angle of friction)

Mechanical Engineering : Theory of Machines - Quiz(MCQ)

Î± = 45Â° -

Î± = 45Â° +

Î± = 90Â° - Ï†

Î± = 90Â° + Ï†

Correct Answer : Option (A) : Î± = 45Â° -

Recently Updated in Theory of Machines Questions

A rotor which is balanced statically but not dynamically is supported on two bearings L apart and at high speed of the rotor, reaction on the left bearing is R. The right side of the bearing is shifted to a new position 2 L apart from the left bearing. At the same rotor speed, dynamic reaction on the left bearing in the new arrangement will

become equal to 2 R

become equal to R/2

become equal to R/4

remain same as before

Correct Answer :

The D-slide valve is also known as

piston slide valve

outside admission valve

inside admission valve

None of the above

Correct Answer : outside admission valve

When the load on the engine increases, it becomes necessary to increase the supply of working fluid and when the load decreases, less working fluid is required. The supply of the working fluid to the engine is controlled by a

governor

flywheel

D-slide valve

Meyer's expansion valve

Correct Answer : governor

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