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TM 5-4210-220-34
3-8.
ENGINE Continued
3-8.3
Blower Continued
(103) Time the rotors to the specified clearance
between the trailing edge of the right-hand
helix rotor and the leading edge of the left-
hand helix rotor (’C’ clearance) measured
from both the inlet and outlet sides. Then,
check the clearance between the leading
edge of the right-hand helix rotor and the
trailing edge of the left-hand rotor (’C’
clearance) for the minimum clearance.
Rotor-to-rotor measurements should be
taken 1 in. (25 mm) from each end and at
the
center
of
the
blower.
Clearance
between rotors: CC Minimum clearance
0.004 -.008 in. (0.10 0.20 mm) C Minimum
clearance 0.010 in. (0.25 mm)
(104) After determining the amount one rotor
must be revolved to obtain the proper
clearance, add shims to the back of the
proper gear to produce the desired result.
When more or less shims are required,
both gears must be removed from the
rotors. Placing a 0.003 in. (0.08 mm) shim
in back of a rotor gear will revolve the rotor
0.001 in. (0.03 mm).
(105) Install the required thickness of shims to
the back of the proper gear and next to the
0.140 in. (3.56 mm) thick gear spacer which
is against the bearing inner race and
reinstall
both
gears.
Recheck
the
clearances between the rotor lobes.
(106) Determine the minimum rotor to end plate
clearances at points (A and B). Insert the
feeler gages between the end plates and
the ends of the rotors. This operation must
be performed at the ends of each lobe,
making 12 measurements in all.
(107) Check the clearance between each rotor
lobe and the blower housing at both the
inlet and outlet side, 12 measurements in
all. The minimum clearances are as shown
in center figure.
NOTE
After the blower rotors are
timed,
complete assembly of the blower by
carrying out steps 108 thru 111.
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