TM 5-3810-300-24&P-3
BLOWER 3.4
rear end plate and thread them into the
housing. Tighten the screws securely. Do
not use lock washers on these screws.
c. Lubricate one of the ball bearings with
engine oil. Start the bearing, numbered
end up, straight on one of the rotor shafts.
d. Place installer J6270-7 on top of the
bearing and tap the bearing straight on the
shaft and into the rear end plate as shown
in Fig. 23.
Fig. 24. Installing Rotor Gears on Rotor Shafts for
e. Install the second ball bearing on the
Preliminary Check of Clearances
remaining rotor shaft in the same manner.
d. Lubricate the serrations of the rotor shafts
f. Place the bearing retainers on top of the
with engine oil.
bearings and the end plate; then, install
the retainer bolts and lock washers.
e. Place the teeth of the rotor gears in mesh
Tighten the bolts to 7-9 lb-ft torque.
so that the omitted serrations inside the
gears are in alignment and facing the
6. Make a preliminary check of the rotor-to-end
same direction as the serrations on the
plate and rotor-to-housing clearances at this time
shafts.
with a feeler gage as shown in Fig. 29. Refer to
Figs. 26 and 27 for minimum blower clearances.
NOTE: A center punch mark placed in
the end of each rotor shaft at the omitted
7. Install the blower rotor timing gears on a
serrations will assist in aligning the gears
standard blower or a smaller diameter rotor
on the shafts.
blower as follows:
f. Start both rotor gears straight on the rotor
One serration is omitted on the drive end of each
shafts with the right-hand helix gear on the
blower rotor shaft and a corresponding serration
right-hand helix rotor and the left-hand
is omitted in each gear. Assemble the gears on
helix gear on the left-hand helix rotor, and
the rotor shafts with the serrations in alignment.
the omitted serrations in the gears in line
with the omitted serrations on rotor shafts.
a. Place the blower housing and rotor
assembly on the bench with the air inlet
g. Thread an installer screw J 6270-8 in the
side of the housing facing up and the rear
end of each rotor shaft until it bottoms.
end (serrated end of rotor shafts) of the
Place gear installer J 6270-7 over the
blower facing the outside of the bench.
installer screw and against the right-hand
helix gear, and gear installer J 6270-6 over
b. Rotate the rotors to bring the omitted
the installer screw and against the left-
serrations on the shafts in alignment and
hand helix gear; then, thread a nut on
facing the top of blower housing (Fig. 28).
each installer screw (Fig. 24).
c. Install the same number and thickness of
h. Place a clean shop towel between the
shims on the rotor shafts that were
rotors, and another one between the rotor
removed at the time of disassembly.
and the housing to prevent the rotors from
turning. Then turn the nuts on the installer
NOTE: When rebuilding a blower with
screws clockwise as shown in Fig. 24 and
new rotors or new gears, first install the
press the gears into position tight against
gears on the rotor shafts without the
the shims and bearing inner races.
shims, then check clearances between
rotors to determine location and thick-
NOTE: Both gears must be pressed on
ness of shims to be used (Fig. 28).
the rotor shafts at the same time.
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