Gear Tooth Contact Pattern

Prior to final assembly, a Gear Tooth Contact Pattern check is necessary to ensure correct relationship between gear sets. Gear sets which are mispositioned may be noisy and have a short life. With a contact pattern check, the most desirable contact between ring gear and drive pinion can be ensured.

1. Wipe oil out of carrier and carefully clean each ring gear tooth.
2. Apply marking compound to all ring gear teeth using a medium stiff brush. When properly used, the pinion tooth contact area will be visible when a hand load is applied.
3. Apply a hand load to companion flange and rotate ring gear one revolution in each direction. Excessive turning of ring gear is not recommended.

Fig. 29 Gear Tooth Contact Pattern:

4. Observe pattern made on ring gear teeth and compare with Fig. 29. A correct contact pattern should be centrally located up and down on the face of the ring gear teeth.