The manufacturing quality of spiral bevel gears has achieved a very high standard. Nevertheless, the understanding of the real stress conditions and the influences. of certain parameters is not satisfactory.
The contact lines of a pair of helical gears move diagonally on the engaged tooth faces and their lengths consequently vary with the rotation of the gears.
Advancements in machining and assembly techniques of thermoplastic gearing along with new design data has lead to increased useage of polymeric materials. information on state of the art methods in fabrication of plastic gearing is presented and the importance
of a proper backlash allowance at installation is discussed. Under controlled conditions, cast nylon gears show 8-14 dBA. lower noise level than three other gear materials tested.
In response to Ed Uberts letter, we have come a long way in gearing since WWII. The Europeans do use long
addendum pinions in many cases. This modification does improve load capacity, sliding conditions and the working life of a gearset. When modifying a pinion tooth it is
necessary to modify the gear tooth or adjust the center distance accordingly but we will leave that to the designers.