Question

The swaying couple is maximum or minimum when the angle of inclination of the crank to the line of stroke ( θ ) is equal to

(a) 45° and 135°

(b) 90° and 135°

(c) 135° and 225°

(d) 45° and 225°

This question was posed to me during an interview.

My query is from Primary and Secondary Unbalanced Forces of Reciprocating Masses in chapter Balancing of Reciprocating Masses of Machine Dynamics

Answer 1

Right option is (d) 45° and 225°

For explanation I would say: The swaying couple is maximum or minimum when (cosθ+sinθ) is maximum or minimum. For (cosθ+sinθ) to be maximum or minimum

                 ∴ tanθ =1 or θ = 45° or 225°