10
field repair
8. Measure fan shaft end play with a dial indicator on a surface
normal to the plane of rotation. Lift shaft axially and rotate
slowly until all axial movement stops. Zero the dial indica-
tor. Lower shaft (zero lifting load) and rotate shaft until axial
movement stops. End play will be read directly from the
dial indicator. Adjust the fan shaft bearings to .003-.005
"
(.076-.127mm) end play. The end play is adjusted by adding
or removing shims (
420
) under the bearing retainer.
INSTALLATION OF PINION CAGE
1. Find the difference between the pinion setting distance of
the old gear and the new pinion gear and adjust the old shim
pack (
320
) or make a new shim pack to compensate for the
different setting distances.
Example:
Pinion setting distance of old gear
6.505
Pinion setting distance of new gear
6.500
Difference
.005
Remove .005 from shim pack.
2. Install pinion cage subassembly into case and tighten cap
screws to 75 ft·lbƒ (102 N·m).
3. Engage pinion gear tooth with “X” marked on end between
ring gear teeth marked with “Xs”. Care must be taken not to
damage the pinion gear teeth by forcing them into the ring
gear teeth.
GEAR SETTING PROCEDURE
The proper mounting of the gear set is essential to obtain long
life and smooth operation of the gears. The pinion and ring gears
were positioned approximately in the preceding steps. The correct
gear position is determined by the gear backlash.
1. Based on the backlash etched on the gear set, find the
equivalent backlash setting in
Table 2
, Column 2.
2. With the “X” marked tooth on the pinion gear engaged be-
tween the two “X” marked teeth on the ring gear, check the
backlash with a dial indicator as shown in
Figure 5
. Lock the
pinion shaft against rotation. The amount of movement of the
fan shaft, measured at a distance equal to the outside radius
of the ring gear is the backlash. Obtain backlash setting by
adjusting ring gear axially by removing or adding shims (
420
)
at bottom bearing cap.
Note
—To maintain the previous fan shaft bearing endplay adjust-
ment, a corresponding shim (
420
) adjustment must be made at
the bearing retainer.
Example:
Removing .003" shims at the bottom bearing cap
requires the addition of .003" shims at the bearing retainer to
maintain correct bearing adjustment.
Recheck the backlash to make sure it is within the proper limits.
3. After the equivalent backlash setting has been obtained with
the marked teeth in mesh, check the backlash at two other
points on the ring gear (points approximately 120° apart).
See
Table 2
, Column 3 for tolerances.
FINAL ASSEMBLY
1. Remove bottom cap and apply a bead of sealant to the bot-
tom cap flange inboard of the bolt holes. Reinstall the bottom
bearing cap and tighten the cap screws to 75 ft·lbƒ (102 N·m).
2. Install O-ring (
502
) in water slinger.
3. Install water slinger on fan shaft (
201
).
4. Replace air vent and all pipe plugs.
5. Fill with lubricant selected from
Table 1
.
COLLAR
SET SCREW
TOP VIEW
OF INDICATOR
POINT OF MEASUREMENT
OUTSIDE RADIUS OF GEAR
DIAL INDICATOR
FIGURE 5
Gear Backlash Measurement
