SQI- 112 - page 9

Bearing life may be substantially increased or decreased
by variations in the operating speed or changes in the
V-belt drive. The table at right lists
the design speeds (RPM) and fan
sheave pitch diameters. The graph
below plots the increase or the
decrease in bearing life when the
RPM or fan sheave pitch diameter
is changed from the values in the
table. Minimum average bearing
life is 75,000 hours.
EXAMPLE:
Determine the increased bearing life of a Size 11 fan
operating at 2525 RPM. Assume the fan sheave pitch
diameter used on this fan is 5.5inches.
1.
Calculate operating RPM as a percent of the design
RPM.
2525 RPM ÷ 2980 RPM = .847 x 100 = 84.7
(Use 85%)
2.
Calculate actual fan sheave pitch diameter as a
percent of the design fan sheave pitch diameter in
the table.
5.5"÷ 6.1" = .902 x 100 = 90.2%
(Use 90%)
3.
Locate the intersection of 85% of design RPM
and 90% of design fan sheave pitch diameter in the
graph. The increased bearing life is 4 times the
design minimum bearing life or 300,000 hours
minimum average life.
9
Group A
T.H. C.W., C.C.W. -T
D.B. C.C.W. - SL
D.B. C.W. - SR
U.B. C.C.W. - SR
U.B. C.W. -SL
Group B
B.H. C.W., C.C.W. -T
D.B. C.C.W. - SR
D.B. C.W. - SL
U.B. C.C.W. - SL
U.B. C.W. -SR
Group C
D.B. C.W., C.C.W. -T
T.H. C.C.W. - SR
T.H. C.W. - SL
B.H. C.C.W. - SL
U.B. C.W. -SR
Group D
U.B. C.W., C.C.W. -T
OFFSET MOTOR BASE
Discharge Position/Rotation and Motor Position
Belt centers include +/– 1-1/2" for belt mounting and tensioning.
Motor Frames can be either “U” or “T” frame.
Refer to factory for Arrangement 9H.
BELT CENTERS
Arrangement 9T, 9S
Discharge Position/Rotation
Group A Group B
Fan
Size
Motor
Frame
Group C Group D
5
6
7
9
11
13
15
17
48
56, 143-145
182-184
48
56, 143-145
182-184
48
56, 143-145
182-184
56, 143-145
182-184
213-215
254-256
56, 143-145
182-184
213-215
254-256
56, 143-145
182-184
213-215
254-256
56, 143-145
182-184
213-215
254-256
56, 143-145
182-184
213-215
254-256
19-13/16
20-5/16
21-5/16
21-5/16
21-13/16
22-13/16
22-13/16
23-5/16
24-13/16
26-5/16
27-5/16
28-1/16
29-1/16
29-3/8
30-3/8
31-1/8
32-1/8
32-15/16
33-15/16
34-11/16
35-11/16
35-15/16
36-15/16
37-11/16
38-11/16
38-15/16
39-15/16
40-11/16
41-11/16
1
8-1/16
18-9/16
19-9/16
19-5/16
19-13/16
20-13/16
20-3/16
20-11/16
21-11/16
23-3/16
24-3/16
24-15/16
25-15/16
25-7/8
26-7/8
27-5/8
28-5/8
28-9/16
29-9/16
30-5/16
31-5/16
31-1/16
32-1/16
32-13/16
33-13/16
33-9/16
34-9/16
35-5/16
36-5/16
18-3/4
19-1/16
20-1/4
20-1/8
20-5/8
21-5/8
20-15/16
21-7/16
22-7/16
24-1/4
25-1/4
26
27
27-1/2
28-1/2
29-1/4
30-1/4
30-1/8
31-1/8
31-7/8
32-7/8
32-7/8
33-7/8
34-5/8
35-5/8
35-9/16
36-9/16
37-5/16
38-5/16
Positions of
Discharge and
Rotation
(viewed from drive side)
BEARING LIFE
5
6
7
9
11
13
15
17
4600
4200
4200
3656
2980
2532
2181
1930
3.0
3.0
3.0
4.5
6.1
7.4
6.3
9.4
Fan
Size
Max.
RPM
Pitch
Dia.
N/A
N/A
N/A
18-1/2
19
20
20
20-1/2
21-1/2
23
24
24-1/2
25-1/2
25-1/2
26-1/2
27-1/4
28-1/4
28
28-7/8
29-1/2
30-1/2
30-5/16
31-5/16
32
33
32-1/2
33-1/2
34-1/2
35-5/16
Bearing Life Chart
1,2,3,4,5,6,7,8 10,11,12
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