Blower Repair & Maintenance Manual #34-05198-6 v1.2 11.2014
13
RESETTING IMPELLER CLEARANCES
Refer to Figure 14 below.
Impellers are held in time by gears which are bolted to a timing hub, which in turn is secured to the
serrated impeller shaft by a lock nut. The timing gears can be rotated in relation to the hub by loosening
the cap screws. Because the cap screw holes in the gear are oversized, the gear hub will rotate
– within
limits
– when the screws are loosened.
To retime, loosen the four cap screws (
A
) to locknut (
B
), and the lock washer (
C
) in one gear only. Wedge
the two impellers together against the exact amount of shim stock required to establish proper clearances
as calculated in the preceding sub-
section: “Determining Proper Impeller Clearances.” Secure the gear in
new position with cap screws (but do not tighten) and rotate impellers by hand. Recheck clearances. If
proper timing has been re-established, tighten cap screws with a torque wrench (refer to accompanying
chart for correct values). Tighten lock washer and locknut.
Install gear case (See Gear Case Removal subsection) and re-lubricate.
Table 3
TORQUE VALUES
5” Gear
6” Gear
42 FT. LBS.
55 FT. LBS.
C
B
A
Fig. 14
