In order to improve the working performance of FH hypoid gears, a ease off active design method for hypoid gears is proposed in this chapter, which considers the transmission strength and dynamic performance. Firstly, according to the generating principle, the transmission relationship without transmission error is replaced by the preset transmission error curve by the gear angle, and the auxiliary tooth surface of the pinion can be obtained.

Then, the contact area of the pinion can be controlled to meet the preset requirements. Finally, in order to make the real tooth surface as close as possible to the target tooth surface, it is necessary to obtain the pinion machining parameter adjustment through the tooth surface error sensitivity function to complete the active design of the gear.

The active design of tooth surface is to design the corresponding tooth surface shape and processing method according to the functional requirements. Finally, the processing parameters of the tooth surface are given to meet the needs. Ease off is the tooth surface mismatch at the corresponding point between the theoretical tooth surface of the small wheel and the fully conjugate tooth surface of the matching large wheel. We call such a topological surface as ease off topological surface based on the small wheel. Similarly, the theoretical tooth surface of large gear and its conjugate pinion tooth surface are also called ease off topological surface based on large wheel.