DESIGN OF SPUR GEAR - Theory of Machines

Sometimes, the spur gears (i.e. driver and driven) are to be designed for the given velocity ratio and distance between the centers of their shafts. Let
x = Distance between the centers of two shafts,
N1 = Speed of the driver,
T1 = Number of teeth on the driver,
d1 = Pitch circle diameter of the driver, N2 , T2 and
d2 = Corresponding values for the driven or follower, and
pc = Circular pitch. We know that the distance between the centers of two shafts,