Parallel-shaft helical gears (helical gears) have an additional helical angle in addition to the same basic parameters as spur gears.Expand the indexing cylindrical surface of the helical gear, in which the shaded part represents the gear section, the blank part represents the gear groove, B is the axial width of the helical gear, PI D is the circumference of the indexing circle, and beta is the helical angle on the indexing cylindrical surface of the helical gear (referred to as helical angle of the helical gear) and PZ is the helical lead.
The expression of indexing cylindrical helical angle of helical gear and helical gear base cylindrical helical angle is obtained.
Because db=dcos alpha t, there are
In the equation, alpha t is the end pressure angle of the helical gear.