Rotax 914 F Maintenance Manual page 99

Progressive pitting: See Pic. 45 and 46
Features:
Limited spalling, normally appearing as pitting zones, spalling base nor-
mally of shell like structure. The total pitting zone might reach a size
impairing smooth engine run or favouring fast ruin of the remaining active
tooth flank by wear.
Cause:
Pitting derive from material fatigue formed by a combination of pressure and
friction started by local exceeding of material strength. Decisive for forma-
tion of pitting: Viscosity and temperature of oil.
Conclusion:
Pitting up to approx. 5% of flank area can be tolerated if the largest
dimension of the spalling does not exceed 0,5 mm.
Modification no.
- 0 -
WARNING: Always exchange gears set wise. Renewal of a single gear
is not permitted
Reference
pitting zone on root of
flank on a spur gear
Pic. 45
magnification: approx.
1,5 times
00151
formation of pitting at root
range on spur gearing
Pic. 46
magnification: approx.
1,5 times
00152
Main
914 F 1997 02 01
Date Page
99