Posted by Bill on April 07, 1999 at 23:11:22:
In Reply to: what' s effects of the helix angle? posted by ercan on April 04, 1999 at 08:54:36:
All other factors being equal, adding helical "twist" or angle to gear teeth has the following results:
(1) Gear set operates more quietly. Transfer of torque from driver to driven gear is smoother and without interruption since multiple teeth are always in contact.
(2) Axial force proportional to SINE of helix angle requires handling thrust loading. Herringbone gears cancel axial thrust by equal and oppositely angled helical gear sections on each gear member.
(3) If OD's are held the same as for spur members, the tooth thickness must decrease. Said another way, the circular pitch or module is reduced. This produces a weaker tooth.
(4) If normal circular pitch is maintained, then OD becomes larger. This is preferred, since tooth thickness is preserved.
(5) Tooth contact in an ideally mounted spur gear set is along the full face width. Helical gears, however, have small tooth contact patterns that travel along a tooth during rotation. Multiple simultaneous tooth contact patterns can occur when face is long enough and helix angle is large enough.