Effects of Increasing Load on Tooth Contact Pattern

When the "load" on the differential ring and drive pinion gear is increased, such as when the vehicle is accelerated forward from a stand still or under normal driving, the tooth contact will tend to spread out and, under a very heavy load, the tooth contact will extend from near toe to near heel on the drive side. The entire contact also tends to shift toward the heel under increasingly heavier loads and will become somewhat broader with respect to tops and bottoms of teeth. The patterns obtained by this tooth contact pattern test approximate a light load and, for this reason, they will extend only about halfway.

The important thing to note is that the contact pattern is centrally located up and down on the face of the differential ring gear teeth.

Insufficiency preloaded drive pinion gear and differential bearings will also cause a change in tooth contact pattern under load.