they have not given which is input and output gear so how we can judge that the answer is 1/8 or 8…..is there any assumption to determine velocity ratio….? I have read on wikipedia that vel. ratio and gear ratio are same is it true..?
The order given in the problem is spur, bevel and spiral gears. We take spur gear as the first driving gear and spiral gear as the last driven gear. According to ‘Theory of Machines’ book by R.S. Khurmi and J.K. Gupta, overall speed ratio of a gear train (SR) is given by
SR = (Speed of the first driver/Speed of the last driven) = (Product of the no. of teeth on the drivens/Product of no. of teeth on the drivers)