EFFECT OF STANDARD PRESSURE ANGLE ON THE FATIGUE STRENGTH OF NITRIDED GEARS.

Nitrided steel gears having three kinds of standard pressure angles were fatigue-tested using a power circulating gear testing machine, in order to elucidate the effect of standard pressure angle on the load carrying capacity and the failure mode of the nitrided gears. The relation between the tooth profile change and the dynamic performance of the gear in the fatigue process was also investigated. The failure modes were tooth breakage at the fillet or grinding notch under a lower pressure angle and higher load and spalling or tooth breakage due to spalling under a higher pressure angle and lower load. The fatigue strength for a normal load increased with increasing pressure angle. The changes in the tooth profile and the dynamic characteristics during the fatigue process were slight.