July/August 1985

Editorial

Despite increased overseas competition, there doesn't seem to be an urge among Americans to attend technical conferences.

Industry Forum

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.

The Design and Manufacture of Plastic Gears Part II

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.

Influence of Relative Displacements Between Pinion and Gear on Tooth Root Stresses of Spiral Bevel Gears

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.

Longitudinal Load Distribution Factor of Helical Gears

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.

Dynamic Analysis of Straight and Involute Tooth Form

The effect of load speed on straight and involute tooth forms is studied using several finite-element models.

Material Selection and Heat Treatment

Before the optimum mechanical properties can be selected, the working stress must be determined, based on recommended allowable stresses.