In Mechanical transmission, the standard gear has a number of advantages of simpledesign, good interchangeability, but it has great limitations to improve the performance ofgear. So the involute shifted gear has applied widely.Comparing to the standard gear, themodified gear has more advantages.It could improve the the pinion tooth root strength, fit thecenter distance, repair the used gear,and so on.So it is very necessary and meaningful toresearch shifted gears. In this paper, I analysed the gear strength...