A new type of profile relief for high contact ratio spur gears

The second of a series of papers on the systematic approach to the profile relief design of both low contact ratio (LCR) and high contact ratio (HCR) spur gears and its effects on transmission error (TE) and tooth loads. Basi cs of the approach are given in the previous paper of the series. Applicati on of the approach to HCR spur gears has produced two promising design case s, namely the short and long reliefs, with advantages and disadvantages. In this paper a new relief type, double relief, is introduced by making use o f the two promising cases. Advantages of the two are brought together, with some compromise. The overall performance of the new relief type, however, is superior to the others in terms of peak-to-peak TE value, maximum tooth load value, rate of tooth loading and number of smooth TE curves, and hence in terms of the range of transmitted load with nearly uniform motion trans fer. A procedure for compensation for adjacent pitch error (PE) with smooth TE curve at off-design load is also included.