116 IM 738-2
Maintenance: Supply Fan Wheel-to-Funnel Alignment
Figure 114. Return fan assembly
Supply Fan Wheel-to-Funnel Alignment
If the unit is equipped with an airfoil or backward curved
supply fan, the fan wheel-to-funnel alignment must be as
shown in Figure 115, Figure 116, Figure 118 and Figure 119 to
obtain proper air delivery and operating clearance. If
necessary
, adjustments are made as follows:
1 Verify that the fan shaft has not moved in its bearings.
2 Loosen the fan hub setscrews and move the wheel(s) along
the shaft as necessary to obtain the correct dimension
shown in Table 29, Table 30, and Table 31.
3 Retighten the setscrews to the torque specification given in
Table 28 on page 115. Tighten the setscrews over the
keyway first; tighten those at 90 degrees to the keyway last.
4 Verify that the radial clearance around the fan is uniform.
Radial clearance can be adjusted by slightly loosening the
funnel hold-down fasteners, shifting the funnel as required,
and retightening the fasteners.
Figure 115. 20" DWDI airfoil wheel-to-funnel (015C to 030C)
Figure 116. 24" DWDI backward curved wheel-to-funnel
(036
C, 040C)
Figure 117. 27 to 40" DWDI airfoil wheel-to-funnel
alignment
Figure 118. 40" SWSI airfoil wheel-to-funnel
alignment
(RDT 045 to 075)
U p p e r B e a r i n g
a n W h e e l
F a n S h a f t
S u p p o r t
L o w e r
B e a r i n g
F a n S h a f t
F u n n e l
. "
. "
W h e e l
Table 29: 27 to 40" DWDI airfoil wheel-to-funnel
relationship
Wheel-to-funnel relationship (in inches)
Wheel diameter (inches) A +0.3/ — 0.0
27 9.9 (246 mm)
30 10.6 (269 mm)
33 11.7 (297 mm)
36 13.1 (333 mm)
40 14.5 (368 mm0
Table 30: SWSI airfoil wheel-to-funnel relationship
Wheel-to-funnel relationship (in inches)
Wheel diameter A
40 0.62
W h e e l
. 8 "
F u n n e l
9 . "
9 . "
C
L
F a n
. 8 "
W h e e l
F u n n e l
A
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