TM 5-3810-300-24&P-3
BLOWER 3.4
the left-hand helix rotor will turn clockwise when viewed
1. 71 Blower - Time the rotors to have .002" to
from the gear end. This positioning of the gear, to obtain
.006" clearance between the TRAILING edge of
the proper clearance between the rotor lobes, is known
the UPPER rotor and LEADING edge of the
as blower timing.
LOWER rotor ("cc" clearance) measured from
both the inlet and outlet sides as shown in Figs.
Moving the gears OUT or IN on the rotor shafts is
25 and 26. If possible, keep this clearance to
accomplished by adding or removing shims between the
the minimum (.002"). Then check the clearance
between the LEADING edge of the UPPER and
the TRAILING edge of the LOWER rotors ("c"
The clearance between the rotor lobes should be
clearance) for the minimum clearance shown in
checked with 1/2" feeler gages in the manner shown in
Fig. 26. Rotor-to-rotor measurements should be
Fig. 25. When measuring clearances of more than
taken 1" from the governor end, at the center,
.005", laminated feeler gages that are made up of .002",
and 1" from the drive end.
.003" or .005" feeler stock are more practical and
suitable than a single feeler gage. Clearances should be
Former Reduction Blowers--Time the rotors to
measured from both the inlet and outlet sides of the
have .002" to .006" clearance between the
blower.
TRAILING edge of the LOWER rotor and the
LEADING edge of the UPPPER rotor ("cc"
A specially designed feeler gage set J 1698-02 for the
clearance) measured from both the inlet and
blower clearance operation is available. Time the rotors
outlet sides as shown in Figs. 25 and 27. If
as follows:
possible keep this clearance to the minimum
Fig. 27. Chart of Minimum Clearances for Former Reduction Blowers
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