The other symbols have the same meaning as in the case of spur gears.
The allowable contact stress is a function of lubrication, gear and pinion material, speed of operation, ambient temperature and cycles of operation during the life of the gear. The most reliable information on -this point is likely to be that obtainable from the plastics manufacturer.
In applying eqs. (73) and (74) it is not always easy to predict the values of the elastic moduli. The values given in the literature such as figures 1.53 and 1.54 are functions of temperature. If the temperature does not vary too much, the ambient temperature can be used for a first estimate.
For bevel gears the determination of contact stresses is beyond the scope of this treatment and the cited references at the end of this section can be consulted for further information.
