The power from one shaft to another shaft is also transmitted with the help of V-belt drive and rope drive. Fig shows a V-belt with a grooved pulley.
Let RN = Normal reaction between belt and sides with a grooved pulley.
2α = Angle of groove
µ = Co-efficient of friction between belt and pulley
R = Total reaction in the plane of groove.
Resolving the forces vertically, we get
R = RN sin α + RN sin α
= 2RN sin α
RN = (R/2) cosec α .....(i)
Frictional resistance = µRN + µRN = 2µRN = 2µ(R/2)cosec α
= µR cosec α = R ⋅ µcosec α
Since in flat belt frictional resistance is equal to µR, and in case of V-belt µcoseca X R So,
Ratio of Tension in V-Belt:: T1/T2 = eµ.θ.cosec α.