AR35.30-P-0475-02F Check Ring Gear/Drive Pinion Contact Pattern

AR35.30-P-0475-02F Check Ring Gear/Drive Pinion Contact Pattern










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Holding device





Checking contact pattern

1 Coat two teeth of ring gear (offset by 180°) with blue ink.
2 Turn the drive pinion forwards and backwards while braking the ring gear with the retainer.
3 Compare contact pattern with contact pattern examples shown below and take specified remedial action if necessary.





Ideal contact pattern

An ideal contact pattern is rarely obtained in practice. It is, however, important to ensure that the contact pattern on the tooth face does not extend to the outside edge of the tooth at any point.

Unacceptable contact patterns




Contact pattern at base of tooth flank

Cause: Installation distance (basic dimension) of drive pinion too small.

Remedy: Slightly increase installation distance (basic dimension) of drive pinion and repeat test of gear backlash, if necessary set gear backlash again.





Contact pattern at crown of tooth flank

Cause: Installation distance (basic dimension) of drive pinion too large.

Remedy: Slightly reduce installation distance (basic dimension) of drive pinion and repeat test of gear backlash, if necessary set gear backlash again.





Contact pattern at tooth heel

Cause: Gear backlash too large.

Remedy: Set gear backlash and repeat gear backlash test.





Contact pattern at tooth toe

Cause: Gear backlash too small.

Remedy: Set gear backlash and repeat gear backlash test.