bpr Rotax 912 i Series, Maintenance Manual, Page: 153 / 458

Effectivity: 912 i Series
Edition 1/Rev. 3
d
066
72.
fm
MAINTENANCE MANUAL
BRP-Powertrain
72-10-00
Page 17
July 01/2018
Fig. 26
DESTRUCTIVE PITTING
See Fig. 27 and Fig. 28.
Features:
Extensive flank fractures, generally occurring as
zones of pitting. The bottom of the fracture gen-
erally has a mussel-shaped structure. The total
pitting area can be so great that the running
smoothness is noticeably affected and/or the
remaining flank area which still bears the load is
rapidly destroyed by wear etc.
Causes:
Pitting is attributable to the fatigue of the material
due to combined stresses from compression and
sliding. They are triggered when the material
strength is exceeded locally. Essential influ-
ences on pit strength are: oil viscosity and oil
temperature.
Conclusion:
Pitting of up to 5% of the flank area is permissi-
ble if the individual flank fractures do not exceed
a size (greatest longitudinal extent) of 0.5 mm.
Otherwise the gear set must be replaced!
Fig. 27
Fig. 28
Magnification: approx. 1.5x
m
WARNUNG
NOTICE
The whole gear set must always be replaced.
Dog hubs or drive gears must not be replaced
individually.
Pitted area in the dedendum flank region of a spur gear.
Magnification approx. 5x.
Pit formation in the dedendum region of a spur gear tooth
system
Magnification approx.
1.5x.