11.FINAL REDUCTION/
TRANSMISSION SYSTEM MXU 500 IRS
TOOTH CONTACT
After backlash adjustment is carried out, the
tooth contact must be checked. Pay attention
to the following procedures:
Remove the driven bevel gear.
Clean and degrease several teeth of the
drive and driven bevel gears. (1)
Apply a coating of machinist's layout dye
or paste to several teeth of the driven bevel
gear.
Install the driven bevel gear.
Rotate the rear propeller shaft several turns
in both directions.
Remove the driven bevel gear and inspect
the coated teeth of the drive bevel gear. The
tooth contact pattern should be as shown in
(1), (2) and (3).
If tooth contact is found to be correct
(example (2)), then to complete installation.
(2)
(1): Incorrect (contact at tooth top)
(2): Correct
(3): Incorrect (contact at tooth root)
If tooth contact is found to be incorrect
(examples (1) and (3)), the shim thickness
between the drive bevel gear and driven
bevel gear must be changed and the tooth
contact rechecked until correct.
Make sure to check the backlash after the
tooth contact has been adjusted, since it (3)
may have changed. Adjust the tooth
contact and backlash until they are both
within specification. If the correct tooth
contact cannot be maintained when
adjusting the backlash, replace the drive
and driven bevel gears.
Tooth contact Drive bevel gear shim adjustment Driven bevel gear shim adjustment
Contact at tooth top Increase shim thickness Increase shim thickness
Contact at tooth root Decrease shim thickness Decrease shim thickness
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