Theory of Machine
The maximum efficiency of spiral gears is (where θ = Shaft angle, and φ = Friction angle)

cos (θ + φ) + 1/ cos (θ - φ) + 1
sin (θ + φ) + 1/ cos (θ - φ) + 1
cos (θ - φ) + 1/ cos (θ + φ) + 1
cos (θ - φ) + 1/ sin (θ + φ) + 1

ANSWER DOWNLOAD EXAMIANS APP

Theory of Machine
In a four bar chain or quadric cycle chain

Each of the four pairs is a turning pair
One is a turning pair and three are sliding pairs
Three are turning pairs and one is a sliding pair
Two are turning pairs and two are sliding pairs

ANSWER DOWNLOAD EXAMIANS APP