Abstract: The mathematic model is established for analyzing engagement of crossed helical involute gears. Through systemic analyzing of the gears transmission with different basic parameters, interrelated rules are found out. The assembling model of one straight gear and one helical gear is brought forward on condi-tion of little axial angle as well as treasures to ameliorate ill engagement performance on condition of large axial angle. The wrong concept is clarified that crossed helical involute gears can only transmit movement but not impetus.

Key words: Computer aided analysis, Crossed helical involute gears, Gear contact analyzing