**Let:**

D1 = Diameter of the driver

N1 = Speed of the driver in R.P.M.

D2 = Diameter of the driven or Follower

N2 = Speed of the driven or follower in R.P.M.

R1 = Radius of the driver

R2 = Radius of the driven or Follower

t = Belt thickness (if given)

X = Distance between the centers of two pulleys

α = Angle of lap (Generally less than 10º)

θ = Angle of contact (Generally greater than 150º) (always express in radian.)

µ = Coefficient of friction s = Total slip in percentage(%) L

= Total length of belt Formula For Open Belt Drive