|Diameter||Up to 20 ft|
|Size||1 m to 25 m|
Helical gears are used increasingly often as power transmitting gears, since not only can they carry larger loads because of their lower dynamic load but also their noise and vibration levels in operation are lower compared with those of spur gears. A lot of studies on root stresses of solid spur gears, solid helical gears and thin-rimmed spur gears have been published by many authors in the past (1-10), but studies on thin-rimmed helical gears are rarely published. The line of contact of helical gear is diagonal across the tooth trace, while the line of contact of spur gear is parallel to the tooth trace. Therefore, root stresses of helical gears can be considered to be quite different from those of spur gears (3,5). Moreover, the deformation of rim part of thin-rimmed helical gear can be considered to be larger than that of solid helical gear. In order to estimate the bending strength of the thin-rimmed helical gear more exactly, it is necessary to determine effects of rim and web thickness on the root stress and the bending fatigue strength. In the previous paper, root stresses and bending fatigue strength of thin-rimmed helical gears with symmetric web arrangement of helix angle β0 = 20° were published by the authors (11-13).