An analytical determination of speed factor in gear designs

In practical gear design, the “speed factor” is usually employed which is defined as a ratio of the allow-able stress at required running speed of the gear system to the stress at zero speed. At present, several expressions for the speed factor are recommended by several authorities; however, those are almost all empirical and not analytical. The present paper aims to contribute to an analytical determination of the speed factor for spur gears as stated below. First, from a dynamic photoelastic test of a pair of spur gears, the following results were obtained:

1. (1)
   At a contant speed and torque and at the same point of engagement, the maximum fillet stress did not have a specific constant value but had somewhat scattered values due to the vibration of gear system under operation.