Brochure

89
CorrectionFactorforBeltLength
Longer belts have greater horsepower ratings because of less frequent
flexure around sheaves.
Multiply H. P. ratings by appropriate factor from table below to get the
final corrected horsepower.
Table No. 1
This and the other information on this page is included for technical support in figuring non-standard drives.
Table No. 2
CorrectionFactorforLossinArcofContact
The loss of arc of contact from 180° for different drives can be deter-
mined in the following manner:
Loss in Arc of Contact (in degrees) = (D - d) 57
C
The Correction Factors for loss in arc of contact in degrees are;
Table No. 3
Table No. 4
*The minimum recommended pitch diameters listed above are RMA and MPTA
Standards recommendations. Many sheaves with diameters smaller than these
recommendations are made and used. If a rating for a “sub-minimum diameter”
sheave is published in the selection tables and the drive is properly installed,
it should give the same theoretical life as a drive using sheave diameters
equal to or greater than the minimums shown above.
2TK
OL =
D
K = 1.0 for Chain Drives
1.25 for Gear Drives
1.25 for Gearbelt Drives
1.50 for V-Belt Drives
2.50 for Flat Belt Drives
LINEAL SHAFT EXPANSION
= .0000063 x length
in inches
x temperature inc.
in degrees F
KW = hp x .7457
IN. = MM/25.4
TEMP °C = (°F-32) .556
LBS = Kg x 2.205
1 hp = 54" lbs. @ 1160 rpm
1 hp = 36" lbs. @ 1750 rpm
FORCE x FPM
hp =
33,000
T " lbs. x rpm
hp =
63,025
T ' lbs. x rpm
hp =
5,252
63,025 x hp
T " lbs. =
rpm
5,252 x hp
T ' lbs. =
rpm
FPM = .2618 x DIA. x rpm
63,025 x hp
rpm =
TORQUE
T = FORCE x LEVER ARM
TORQUE
F =
RADIUS
FPM
rpm =
.2618 x DIA.
Nominal
Length
A B C
Nominal
Length
A B C D E
26 .81 — — 90 1.06 1.00 .91 — —
31 .84 — — 93 — 1.01 — — —
32 .85 — — 96 1.08 1.02 .92 — —
33 .86 — — 97 — 1.02 — — —
34 .86 — — 99 — 1.02 — — —
35 .87 .81 — 100 — 1.03 — — —
36 .87 — — 103 — 1.03 — — —
37 .88 — — 105 1.10 1.04 .94 — —
38 .88 .83 — 108 — 1.04 — — —
42 .90 .85 — 109 — — .94 — —
43 .90 — — 110 1.11 — — — —
46 .92 .87 — 112 1.11 1.05 .95 — —
48 .93 .88 — 115 — — .96 — —
50 — .89 — 116 — 1.06 — — —
51 .94 .89 .80 120 1.13 1.07 .97 .86 —
52 — .89 — 124 — 1.07 — .87 —
53 .95 .90 — 128 1.14 1.08 .98 — —
54 .95 .90 — 133 — 1.08 — — —
55 .96 .90 — 136 1.15 1.09 .99 — —
56 .96 .90 — 144 1.16 1.11 1.00 .90 .88
58 .97 .91 — 150 — 1.12 1.01 — —
59 — .91 — 158 1.17 1.13 1.02 .92 —
60 .98 .92 .82 162 — 1.13 1.03 .92 —
61 — .92 — 173 1.18 1.15 1.04 .93 —
62 .99 .93 — 180 1.19 1.16 1.05 .94 .91
63 — .93 — 195 — 1.18 1.07 .96 .92
64 .99 .93 — 210 — 1.19 1.08 .96 .94
65 — .94 — 225 — 1.20 1.09 .98 .95
66 1.00 .94 — 240 — 1.22 1.11 1.00 .96
67 — .94 — 255 — 1.23 1.12 1.01 —
68 1.00 .95 .85 270 — 1.25 1.14 1.03 .99
70 1.01 .95 — 285 — 1.26 1.15 1.04 —
71 1.01 .95 — 300 — 1.27 1.16 1.05 1.01
75 1.02 .97 .87 315 — 1.28 1.17 1.06 —
77 — .98 — 330 — — 1.19 1.07 1.03
78 1.03 .98 — 345 — — 1.20 1.08 —
79 — .98 — 360 — 1.31 1.21 1.09 1.05
80 1.04 .98 — 390 — — 1.23 1.11 1.07
81 — .98 .89 420 — — 1.24
1.12
1.09
82 — .99 — 480 — — — 1.16 1.12
83 — .99 — 540 — — — 1.18 1.14
85 1.05 .99 .90 600 — — — 1.20 1.17
88 — 1.00 —
Belt
Length
Cross Section
Belt
Length
Cross Section
3V 5V 8V 3V 5V 8V
25.0 .83 — — 112.0 1.11 .98 .88
26.5 .84 — — 118.0 1.12 .99 .89
28.0 .85 — — 125.0 1.13 1.00 .90
30.0 .86 — — 132.0 1.14 1.01 .91
31.5 .87 — — 140.0 1.15 1.02 .92
33.5 .88 — — 150.0 — 1.03 .93
35.5 .89 — — 160.0 — 1.04 .94
37.5 .91 — — 170.0 — 1.05 .95
40.0 .92 — — 180.0 — 1.06 .95
42.5 .93 — — 190.0 — 1.07 .96
45.0 .94 — — 200.0 — 1.08 .97
47.5 .95 — — 212.0 — 1.09 .98
50.0 .96 .85 — 224.0 — 1.09 .98
53.0 .97 .86 — 236.0 — 1.10 .99
56.0 .98 .87 — 250.0 — 1.11 1.00
60.0 .99 .88 — 265.0 — 1.12 1.01
63.0 1.00 .89 — 280.0 — 1.13 1.02
67.0 1.01 .90 — 300.0 — 1.14 1.03
71.0 1.02 .91 — 315.0 — 1.15 1.03
75.0 1.03 .92 — 335.0 — 1.16 1.04
80.0 1.04 .93 — 355.0 — 1.17 1.05
85.0 1.06 .94 — 375.0 — — 1.06
90.0 1.07 .95 — 400.0 — — 1.07
95.0 1.08 .96 — 425.0 — — 1.08
100.0 1.09 .96 .87 450.0 — — 1.09
106.0 1.10 .97 .88
Loss in Arc Correction
of Contact Factor
Loss in Arc Correction
of Contact Factor
0°................................ 1.00 50°.............................. .86
5°................................ .99 55°.............................. .84
10°.............................. .98 60°.............................. .83
15°.............................. .96 65°.............................. .81
20°.............................. .95 70°.............................. .79
25°.............................. .93 75°.............................. .76
30°.............................. .92 80°.............................. .74
35°.............................. .90 85°.............................. .71
40°.............................. .89 90°.............................. .69
45°.............................. .87
Belt
Selection
Nominal
Belt Size
Add to
D.D. / P.D.
to get O.D.
Minimum
Recommended
Pitch Diameter*
C D
A 1/2” x 5/16” .25” 3.00” 3/8” 5/8”
B 21/32 x 13/32 .35 5.40 1/2 3/4
C 7/8 x 17/32 .40 9.00 11/16 1
D 1 1/4 x 3/4 .64 13.00 7/8 1 7/16
E 1 1/2 x 29/32 .82 21.00
1 1/8 1 3/4
3V 3/8 x 5/16 .05 2.60 11/32 13/32
5V 5/8 x 7/16 .10 7.00 1/2 11/16
8V 1 x 7/8 .20 12.50 3/4 1 1/8