A 60 – teeth gear when hobbed on a differential hobber with a two –start hob, the index change gear ratio is governed by which one of the following kinematic balance equations?
(a) 1 revolution of gear blank = 1/60 of hob revolutions
(b) 1 revolution of gear blank = 2/60 of hob revolutions
(c) 1 revolution of hob = 2/60 of blank revolutions
(d) 1 revolution of hob = 1/60 of blank revolutions