V-BELT TENSIONING
IMPORTANT
Although the values in the Average Tensioning Values Table included in this brochure can be used satisfactorily for most V-belt drives, they are based on drives which are designed using recommended procedures and ratings in the Carlisle Engineering Guide for Industrial V-Belt Drives (102161). They DO NOT, for example, consider drives originally designed for wrapped type belts, which are later upgraded to the premium Power-Wedge® Cog-Belt® (3VX, 5VX, 8VX) belts or Gold Label® Cog-Belt® (AX, BX, CX, DX) belts. In these cases, where known, the values for the wrapped type Super Power-Wedge® (3V, 5V, 8V) belts or Super Blue Ribbon® (AP, BP, CP, DP) belts should be used. For more precise tension values, Carlisle recommends that the “Formula Method” of tensioning described in the Engineering Guide for Industrial V-Belt Drives be used. Failure to observe the limitations of the Average Tensioning Values Table may result in excessive loads on bearings and/or shafts.
Gold Label® is a registered trade mark of Dayco Products, LLC
V-BELT TENSIONING
INTRODUCTION
Because V-belts operate on the friction principle, multiplied by the mechanical advantage of the wedging principle, proper tensioning of v-belts is the single most important factor necessary for long, satisfactory operation. Too little tension will result in slippage, causing rapid belt and sheave wear, and loss of productivity. Too much tension can result in excessive stress on belts, bearings, and shafts and reduced efficiency.
However, there is still a wide range of tension within which a drive will operate satisfactorily. It is the intent of this section to permit the engineer to find this proper range for any V-belt drive.
THE EFFECT OF TECHNOLOGY ON TENSIONING
Prior to 1956, V-belt tensioning was readily accomplished by simple procedures such as thumb pressure, slapping the belts, etc. Since that time. new materials, especially synthetic fibers, and new processes have permitted V-belt manufacturers to increase horsepower ratings. In addition, newer high capacity cross-sections (3V, 5V, 8V) have been introduced.
As horsepower ratings for individual belts were increased, and belt cross section became smaller, the number of belts on a drive were decreased, resulting in higher tensions per belt. It therefore has become increasingly difficult to judge proper tensioning by former thumb-pressure techniques.
To further complicate matters, the existence of older design and newer design drives in the same plant creates a multiple standard for tensioning. For example, a drive designed in 1955, equipped with today’s higher rated V-belts, would in effect be over belted by 120%.
METHODS OF TENSIONING V-BELTS
It should be noted by the engineer, that the most precise way of determining proper V-belt tensions is by the “Formula Method” described on the following pages. However, recognizing that this method is sometimes impractical, we also offer the “General Method” and tables of average values. In most cases, these will prove adequate. In all cases, care should be exercised regarding sheave groove wear and alignment, as these factors play an important part in achieving the long, trouble-free service associated with V-belt drives.
GENERAL METHOD
A few simple rules should be followed to satisfy most drive requirements:
1. For installation, reduce the center distance so the belts may be placed in the sheave grooves without force. Arrange the belts so that both the top and bottom spans have about the same amount of sag. Apply tension to the belts by increasing the center distance until the belts are snug and have a live, springy action when struck with the hand.
2. Operate the drive a few minutes to seat the belts in the sheave grooves. Observe the operation of the drive under its highest load condition (usually starting). A slight bowing of the slack side of the drive indicates adequate tension. If the slack side remains taut during the peak load, the drive is too tight.
3. Check the tension on a new drive several times during the first 24 hours of operation, by observing the slack side span.
4. Keep the drive free of foreign material which might cause slippage or damage to the belt and sheave surfaces.
5. If a V-belt slips, it is too loose. Increase the tension by increasing the center distance. Never apply belt dressing, as this will damage the belt and cause early failure.
V-BELT TENSIONING (Continued)
Table 29 Factors Table
Arc of Contact (degrees) (D-d) C A B H K M N (Cq) O
180 179 178 177 176 0.000 0.017 0.035 0.052 0.070 — 57.297 28.649 19.101 14.327 1.000 1.000 1.000 1.000 0.999 2.000 2.000 2.000 1.999 1.999 24.750 24.843 24.937 25.032 25.129 1.000 1.000 1.000 1.000 0.999 1.00 1.00 1.00 0.99 0.99 0.75 0.75 0.76 0.76 0.76
175 174 173 172 171 0.087 0.105 0.122 0.140 0.157 11.463 9.554 8.190 7.168 6.373 0.999 0.998 0.998 0.997 0.996 1.998 1.997 1.996 1.995 1.994 25.227 25.326 25.427 25.529 25.632 0.999 0.999 0.998 0.998 0.997 0.99 0.99 0.98 0.98 0.9 0.76 0.77 0.77 0.77 0.77
170 169 168 167 166 0.174 0.192 0.209 0.226 0.244 5.737 5.217 4.783 4.417 4.103 0.996 0.995 0.994 0.993 0.992 1.992 1.991 1.989 1.987 1.985 25.737 25.844 25.952 26.061 26.172 0.996 0.995 0.995 0.994 0.993 0.98 0.97 0.97 0.97 0.97 0.77 0.78 0.78 0.78 0.78
165 164 163 162 161 0.261 0.278 0.296 0.313 0.330 3.831 3.593 3.383 3.196 3.029 0.991 0.990 0.988 0.987 0.986 1.983 1.981 1.978 1.975 1.973 26.285 26.399 26.515 26.633 26.752 0.992 0.990 0.989 0.988 0.987 0.96 0.96 0.96 0.96 0.95 0.79 0.79 0.79 0.79 0.80
160 159 158 157 156 0.347 0.364 0.382 0.399 0.416 2.879 2.744 2.620 2.508 2.405 0.984 0.983 0.981 0.979 0.977 1.970 1.967 1.963 1.960 1.956 26.873 26.996 27.120 27.247 27.375 0.985 0.984 0.982 0.980 0.979 0.95 0.95 0.95 0.94 0.94 0.80 0.80 0.80 0.81 0.81
155 154 153 152 151 0.433 0.450 0.467 0.484 0.501 2.310 2.223 2.142 2.067 1.997 0.975 0.973 0.971 0.969 0.967 1.953 1.949 1.945 1.941 1.936 27.505 27.638 27.772 27.908 28.046 0.977 0.975 0.973 0.971 0.969 0.94 0.93 0.93 0.93 0.93 0.81 0.81 0.81 0.82 0.82
150 149 148 147 146 0.518 0.534 0.551 0.568 0.585 1.932 1.871 1.814 1.760 1.710 0.965 0.962 0.960 0.957 0.954 1.932 0.927 1.923 1.918 1.913 28.187 28.329 28.474 28.621 28.771 0.967 0.965 0.963 0.961 0.959 0.92 0.92 0.92 0.91 0.91 0.82 0.82 0.83 0.83 0.83
145 144 143 142 141 0.601 0.618 0.635 0.651 0.668 1.663 1.618 1.576 1.536 1.498 0.952 0.949 0.946 0.943 0.940 1.907 1.902 1.897 1.891 1.885 28.922 29.076 29.233 29.392 29.553 0.956 0.954 0.952 0.949 0.947 0.91 0.91 0.90 0.90 0.90 0.83 0.83 0.84 0.84 0.84
Arc of Contact (degrees) (D-d) C A B H K M N (Cq) O
140 139 138 137 136 0.684 0.700 0.717 0.733 0.749 1.462 1.428 1.395 1.364 1.335 0.936 0.933 0.930 0.926 0.922 1.879 1.873 1.867 1.861 1.854 29.718 29.884 30.054 30.226 30.402 0.944 0.942 0.939 0.936 0.934 0.89 0.89 0.89 0.88 0.88 0.84 0.84 0.85 0.85 0.85
135 134 133 132 131 0.765 0.781 0.797 0.813 0.829 1.307 1.280 1.254 1.229 1.206 0.919 0.915 0.911 0.907 0.903 1.848 1.841 1.834 1.827 1.820 30.580 30.761 30.945 31.132 31.323 0.931 0.928 0.925 0.923 0.920 0.88 0.87 0.87 0.87 0.86 0.85 0.85 0.86 0.86 0.86
130 129 128 127 126 0.845 0.861 0.877 0.892 0.908 1.183 1.161 1.141 1.121 1.101 0.898 0.894 0.889 0.885 0.880 1.813 1.805 1.798 1.790 1.782 31.516 31.713 31.914 32.118 32.325 0.917 0.914 0.911 0.908 0.905 0.86 0.86 0.85 0.85 0.84 0.86 0.86 0.85 0.85 0.84
125 123 122 121 0.939 0.954 0.970 0.985 1.065 1.048 1.031 1.015 0.870 0.864 0.859 0.853 1.766 1.758 1.749 1.741 32.752 32.970 33.193 33.420 0.899 0.896 0.893 0.890 0.84 0.83 0.83 0.83 0.84 0.83 0.83 0.83
120 119 118 117 116 1.000 1.015 1.030 1.045 1.060 1.000 0.985 0.971 0.957 0.944 0.847 0.841 0.835 0.829 0.822 1.732 1.723 1.714 1.705 1.696 33.651 33.886 34.126 34.370 34.618 0.887 0.884 0.880 0.877 0.874 0.82 0.82 0.81 0.81 0.81 0.82 0.82 0.81 0.81 0.81
115 114 113 112 111 1.075 1.089 1.104 1.118 1.133 0.931 0.918 0.906 0.894 0.883 0.815 0.808 0.801 0.793 0.785 1.687 1.677 1.668 1.658 1.648 34.871 35.130 35.393 35.661 35.934 0.871 0.868 0.865 0.861 0.858 0.80 0.80 0.79 0.79 0.79 0.80 0.80 0.79 0.79 0.79
110 109 108 107 106 1.147 1.161 1.176 1.190 1.204 0.872 0.861 0.851 0.841 0.831 0.776 0.767 0.757 0.747 0.736 1.638 1.628 1.618 1.608 1.597 36.213 36.497 36.787 37.083 37.385 0.855 0.852 0.849 0.845 0.842 0.78 0.78 0.77 0.77 0.77 0.78 0.78 0.77 0.77 0.77
105 104 103 102 101 1.218 1.231 1.245 1.259 1.272 0.821 0.812 0.803 0.795 0.786 0.724 0.710 0.694 0.675 0.644 1.587 1.576 1.565 1.554 1.543 37.693 38.008 38.328 38.656 38.991 0.839 0.836 0.833 0.830 0.826 0.76 0.76 0.75 0.75 0.74 0.76 0.76 0.75 0.75 0.74
V-BELT TENSIONING (Continued)
Strand Deflection — Formula Method
This method is based on the fact that the force required to deflect a given span length by a given amount is related to the tension in the belt. (Note: If the drive uses banded V-belts, use “Belt Elongation Method.” See page 10.
Step 1. Install the belts per rules 1 and 2 of the “General Method” discussed previously. Measure span length (t) in inches as shown in Figure 26, or calculate as follows:
2
D-d
t = C2
(2
Where: t = span length, in inches C = center distance, in inches
(
D = large sheave pitch diameter, in inches d = small sheave pitch diameter, in inches
Step 2. Calculate the deflection distance by: t/64 = deflection. Note from Figure 26 that the deflection distance is always 1/64. per inch of span length (for example, a 32. span length would require a deflection of 32/64 or 1/2 inch).
Step 3. Calculate the static strand tension (Ts) per belt by the following formula:
Design HP x K
Ts= + Tc
Q x S
D - d
Where: K = value from Table 29 depending on value of
C
Q = number of belts/ribs on drive
S = belt speed, feet per minute / 1000
Tc = add-on tension allowance for centrifugal force, from Table 31 on page 291.
Note: The value of Ts is for an individual V-belt. If a banded V-belt is used, refer to “Elongation Method.”
Step 4. Calculate the recommended minimum and maximum deflection forces (P), in pounds:
Ts+ Y (1.5 x Ts) + Y
= =
Pmin Pmax
16 16
Where:
Ts = Static strand tension (from Step 3)
Y = Constant from Table 30 on page 289
V-BELT TENSIONING (Continued)
TABLE 30 - FACTORS Cc &Y
BELT CROSS SECTION Cc SINGLE BELTS Cc BANDED BELTS Y
A 0.72 - 6.00
AP 0.72 0.86 5.00
AX 0.68 0.81 6.00
B 0.99 - 9.00
BP 1.09 1.36 8.00
BX 0.95 1.17 9.00
C 2.09 - 18.00
CP 1.84 2.24 18.00
CX 1.69 - 19.00
DP 3.65 4.19 28.00
DX 3.83 4.78 40.00
3VX 0.55 0.47 4.00
5VX/5V 1.25 1.32 11.00
8V 2.95 3.46 25.00
8VX 2.95 3.46 30.00
NOTE: For drives using only one belt, and at least one shaft is free to turn, use the following for the deflection forces (P):
Ts+ Ltr (1.5xTs) + LtY
Pmin = Pmax =
16 16
Where: t = span length, inches (from step 1)
L = belt pitch length, inches
Y = constant from Table 30 above
STEP 5
Tension the V-belts by this procedure:
a) Using a Carlisle Tensiometer (part no. 102761), or other suitable spring scale, apply force to ONE belt of the drive, perpendicular to the span at its mid-point, as shown in figure 27. See Page 13 for the Tensiometer instructions.
b) Measure the deflecting force being applied when the belt has been deflected the distance calculated in Step 2 (use an adjacent belt as reference point; on single belt drives, use straight edge or taut string across sheaves). The measured force should be between the values of Pmin and Pmax calculated in Step 4. If the measured force is outside these values, adjust center distance to increase or reduce tension, and repeat above procedure. On multiple belt drives an average of readings on each belt is recommended.
NOTE: If new belts are being installed for the first time, it is permissible to tension as much as 1.33 x Pmax to allow for initial stretch and seating in the grooves.
STEP 6
During the first 24 hours of operation, it is advisable to repeat the procedure in Step 5 at least once.
V-BELT TENSIONING (Continued)
Example of Determining Tension by Formula Method
Given drive parameters:
Driven HP = 25
Driver = 6 groove, C section, 10.0” p.d. (@ 1750 RPM)
Driven = 6 groove, C section, 30.0” p.d.
Belts = 6 CP162 Super Blue Ribbon
Center Distance = 50.0”
STEP 1
Measure span length (t), or calculate as:
2 (D - d
)
2
t =
C-2 =
2 (30-10 0 )2
t =
(50)-2 = 49.0”
STEP 2
Calculate deflection distance: t = 49/64”
STEP 3
To find Static Strand Tension (Ts), first calculate: 10 x 1750 x .262
S (fpm/1000) = = 4.585
1000 D-d 30-10
== 0.4
C 50
and find factor K from Table 29 on Page 287. K = 27.257 (interpolating)
Design Horspowerx K
125 x 27.257
Ts = + Tc (from Table 31)
QxS = + 20.8 = 144.7 lbs.
6 x 4.585
V-BELT TENSIONING (Continued)
STEP 4
Calculate minimum and maximum deflection forces:
Ts+Y 144.7 + 16 Pmin = = = 10 lbs.
16 16
(1.5 x Ts) + Y 217.1 + 16
Pmax = = = 14.6 lbs.
16 16
STEP 5
Belts are tensioned at deflection distance of 49/64” until force readings are between 10 and 15 lbs. If belts are new, between 15 and 20 lbs.)
ALTERNATE FORMULA FOR FINDING STRAND TENSION (Ts):
2.5 - N Design HP Cc x S2
Ts = 16.5 ( )( ) +
N Q x S 2
Where: N = Arc Correction Factor, Table 29 Q = Number of belts on drive Cc = Centrifugal constant from Table 30 S = Belt speed, feet per minute/1000
TABLE 31 - Tc CENTRIFUGAL TENSION ADD-ON VALUES FOR CALCULATING STATIC STRAND TENSION (Ts) OF INDIVIDUAL V-BELTS. (FOR BANDED BELTS SEE TABLE 32)
S fpm 1000 POWER-WEDGE COG-BELT SUPER POWER WEDGE SUPER BLUE RIBBON & ARAMAX GOLD LABEL COG & SUPER II
3VX 5VX 8VX 5V 8V AP AK BP BK CP CK DP AX A BX B CX C DX D
0.50 0.05 0.13 0.44 0.15 0.41 0.08 0.13 0.25 0.47 0.08 0.13 0.22 0.50
0.75 0.11 0.30 0.98 0.34 0.92 0.19 0.30 0.56 1.05 0.17 0.28 0.50 1.12
1.00 0.19 0.54 1.74 0.61 1.64 0.33 0.54 0.99 1.87 0.31 0.50 0.89 1.98
1.25 0.30 0.84 2.72 0.96 2.56 0.52 0.84 1.54 2.92 0.48 0.78 1.39 3.10
1.50 0.44 1.21 3.92 1.38 3.69 0.75 1.21 2.22 4.20 0.69 1.13 2.00 4.46
1.75 0.59 1.65 5.34 1.88 5.02 1.02 1.65 3.03 5.72 0.94 1.53 2.72 6.08
2.00 0.78 2.16 6.97 2.45 6.56 1.33 2.16 3.95 7.47 1.23 2.00 3.55 7.94
2.25 0.98 2.73 8.82 3.10 8.30 1.68 2.73 5.00 9.46 1.55 2.53 4.50 10.05
2.50 1.21 3.37 10.89 3.83 10.24 2.08 3.37 6.17 11.67 1.91 3.13 5.55 12.40
2.75 1.47 4.08 13.18 4.63 12.40 2.51 4.08 7.47 14.12 2.32 3.78 6.72 15.01
3.00 1.75 4.85 15.68 5.51 14.75 2.99 4.85 8.89 16.81 2.76 4.50 8.00 17.86
3.25 2.05 5.70 18.41 6.47 17.31 3.51 5.70 10.43 19.73 3.23 5.29 9.39 20.96
3.50 2.38 6.61 21.35 7.50 20.08 4.07 6.61 12.10 22.88 3.75 6.13 10.89 24.31
3.75 2.73 7.58 24.51 8.61 23.05 4.67 7.58 13.89 26.27 4.31 7.04 12.50 27.90
4.00 3.11 8.63 27.88 9.80 26.23 5.31 8.63 15.80 29.88 4.90 8.01 14.22 31.75
4.25 3.51 9.74 31.48 11.06 29.61 6.00 9.74 17.84 33.74 5.53 9.04 16.05 35.84
4.50 3.93 10.92 35.29 12.40 33.19 6.73 10.92 20.00 37.82 6.20 10.13 17.99 40.18
4.75 4.38 12.17 39.32 13.82 36.98 7.49 12.17 22.29 42.14 6.91 11.29 20.05 44.77
5.00 4.85 13.48 43.57 15.31 40.98 8.30 13.48 24.69 46.69 7.66 12.51 22.21 49.61
5.25 5.35 14.86 48.03 16.88 45.18 9.15 14.86 27.23 51.48 8.44 13.79 24.49 54.69
5.50 5.87 16.31 52.72 18.53 49.58 10.05 16.31 29.88 56.50 9.26 15.14 26.88 60.02
5.75 6.42 17.83 57.62 20.25 54.19 10.98 17.83 32.66 61.75 10.13 16.54 29.38 65.60
6.00 6.99 19.41 62.74 22.05 59.01 11.96 19.41 35.56 67.24 11.03 18.01 31.99 71.43
6.25 7.58 21.06 68.07 23.93 64.03 12.97 21.06 38.59 72.96 11.96 19.55 34.71 77.51
6.50 8.20 22.78 73.63 25.88 69.25 14.03 22.78 41.73 78.91 12.94 21.14 37.54 83.83
6.75 8.84 24.57 79.40 27.91 74.68 15.13 24.57 45.01 85.10 13.95 22.80 40.49 90.41
7.00 9.51 26.42 85.39 30.01 80.32 16.27 26.42 48.40 91.52 15.01 24.52 43.54 97.23
NOTE: When value of S is greater than 6.00, special sheaves and/or dynamic balancing may be necessary. See Page 236 of the Carlisle V-Belt Drive Design catalog (102161)
V-BELT TENSIONING (Continued)
TABLE 32 - Tc CENTRIFUGAL TENSION ADD-ON VALUES FOR CALCULATING STATIC STRAND TENSION (Ts) OF BANDED V-BELTS. (FOR INDIVIDUAL V-BELTS SEE TABLE 31)
S fpm 1000 Wedge-Band Super Vee-Band Gold Label Cog-Band
R3V R5V R8V RBP RCP RDP RBX RCX RDX
0.50 0.06 0.16 0.47 0.17 0.29 0.54 0.16 0.26 0.57
0.75 0.14 0.37 1.07 0.39 0.66 1.21 0.36 0.59 1.28
1.00 0.25 1.03 2.97 1.08 1.82 3.35 1.00 1.64 3.56
1.25 0.40 1.03 2.97 1.08 1.82 3.35 1.00 1.64 3.56
1.50 0.57 1.48 4.27 1.55 2.62 4.82 1.44 2.36 5.12
1.75 0.78 2.02 5.81 2.11 3.57 6.57 1.96 3.21 6.97
2.00 1.02 2.64 7.59 2.76 4.66 8.58 2.55 4.19 9.11
2.25 1.29 3.34 9.61 3.49 5.90 10.85 3.23 5.31 11.53
2.50 1.59 4.12 11.86 4.31 7.28 13.40 3.99 6.55 14.23
2.75 1.92 4.99 14.35 5.22 8.81 16.21 4.83 7.93 17.22
3.00 2.29 5.94 17.08 6.21 10.48 19.29 5.75 9.43 20.50
3.25 2.69 6.97 20.05 7.29 12.30 22.64 6.74 11.07 24.06
3.50 3.12 8.08 23.25 8.45 14.27 26.26 7.82 12.84 27.90
3.75 3.58 9.28 26.69 9.71 16.38 30.15 8.98 14.74 32.03
4.00 4.07 10.56 30.37 11.04 18.63 34.30 10.21 16.77 36.44
4.25 4.60 11.92 34.28 12.47 21.04 38.72 11.53 18.93 41.14
4.50 5.15 13.36 38.43 13.98 23.58 43.41 12.93 21.23 46.12
4.75 5.74 14.89 42.82 15.57 26.28 48.37 14.40 23.65 51.39
5.00 6.36 16.50 47.45 17.25 29.12 53.60 15.96 26.20 56.94
5.25 7.01 18.19 52.31 19.02 32.10 59.09 17.69 28.89 62.77
5.50 7.70 19.96 57.41 20.88 35.23 64.85 19.31 31.71 68.90
5.75 8.41 21.82 62.75 22.82 38.51 70.88 21.11 34.66 75.30
6.00 9.16 23.76 68.33 24.85 41.93 77.18 22.98 37.73 81.99
6.25 9.94 25.78 74.14 26.96 45.49 83.74 24.94 40.94 88.97
6.50 10.75 27.88 80.19 29.16 49.21 90.58 26.97 44.29 96.23
6.75 11.60 30.07 86.47 31.45 53.06 97.68 29.09 47.76 103.77
7.00 12.47 32.34 93.00 33.82 57.07 105.05 31.28 51.36 111.60
NOTE
When value of S is greater than 6.00, special sheaves and/or dynamic balancing may be necessary - see Page 236 of the Carlisle V Belt Drive design catalog 102161
AVERAGE TENSIONING TABLES
Although the Formula Method is recommended for the most accurate means of determining V-Belt tension, Table 33 may be used satisfactorily for most drives. However, these values are based on drives which are designed using recommended procedures and ratings in this catalog for the belt types and cross-sections indicated in the tables. They do NOT, for example, consider drives originally designed for wrapped-type belts, which are later upgraded to the premium Power-Wedge Cog-Belt or Gold Label Cog-Belt. In these cases, where known, the values for the wrapped-type Super Power-Wedge or Super Blue Ribbon should be used.
Failure to observe these limitations of the tables may result in excessive loads on bearings and/or shafts.
V-BELT TENSIONING (Continued)
TABLE 33 AVERAGE TENSIONING VALUES (RECOMMENDED MINIMUM FORCE PER BELT)
V-Belt Type V-Belt Section Small Sheave Deflection Force for Drive Speed Ratio (lbs.)
Speed Range Diameter 1.00 1.5 2.0 4.0 & over
Super II Super Blue Ribbon A AP 1800-3600 3.0 2.0 2.3 2.4 3.3
1800-3600 4.0 2.6 2.8 3.0 3.3
1800-3600 5.0 3.0 3.3 3.4 3.7
1800-3600 7.0 3.5 3.7 3.8 4.3
B BP 1200-1800 4.6 3.7 4.3 4.5 5.0
1200-1800 5.0 4.1 4.6 4.8 5.6
1200-1800 6.0 4.8 5.3 5.5 6.3
1200-1800 8.0 5.7 6.2 6.4 7.2
C CP 900-1800 7.0 6.5 7.0 8.0 9.0
900-1800 9.0 8.0 9.0 10.0 11.0
900-1800 12.0 10.0 11.0 12.0 13.0
700-1500 16.0 12.0 13.0 13.0 14.0
DP 900-1500 12.0 13.0 15.0 16.0 17.0
900-1500 15.0 16.0 18.0 19.0 21.0
700-1200 18.0 19.0 21.0 22.0 24.0
700-1200 22.0 22.0 23.0 24.0 26.0
Gold Label® Cog-Belt AX 1800-3600 3.0 2.5 2.8 3.0 3.3
1800-3600 4.0 3.3 3.6 3.8 4.2
1800-3600 5.0 3.7 4.1 4.3 4.6
1800-3600 7.0 4.3 4.6 4.8 5.3
BX 1200-1800 4.6 5.2 5.8 6.0 6.9
1200-1800 5.0 5.4 6.0 6.3 7.1
1200-1800 6.0 6.0 6.4 6.7 7.7
1200-1800 8.0 6.6 7.1 7.5 8.2
CX 900-1800 7.0 10.0 11.0 12.0 13.0
900-1800 9.0 11.0 12.0 13.0 14.0
900-1800 12.0 12.0 13.0 13.0 14.0
700-1500 16.0 13.0 14.0 14.0 15.0
DX 900-1500 12.0 16.0 18.0 19.0 20.0
900-1500 15.0 19.0 21.0 22.0 24.0
700-1200 18.0 22.0 24.0 25.0 27.0
700-1200 22.0 25.0 27.0 28.0 30.0
Power-Wedge Cog-Belt 3VX 1200-3600 2.2 2.2 2.5 2.7 3.0
1200-3600 2.5 2.6 2.9 3.1 3.6
1200-3600 3.0 3.1 3.5 3.7 4.2
1200-3600 4.1 3.9 4.3 4.5 5.1
1200-3600 5.3 4.6 4.9 5.1 5.7
1200-3600 6.9 5.0 5.4 5.6 6.2
5VX 1200-3600 4.4 6.5 7.5 8.0 9.0
1200-3600 5.2 8.0 9.0 9.5 10.0
1200-3600 6.3 9.5 10.0 11.0 12.0
1200-3600 7.1 10.0 11.0 12.0 13.0
900-1800 9.0 12.0 13.0 14.0 15.0
900-1800 14.0 14.0 15.0 16.0 17.0
8VX 900-1800 12.5 18.0 21.0 23.0 25.0
900-1800 14.0 21.0 23.0 24.0 28.0
700-1500 17.0 24.0 26.0 28.0 30.0
700-1200 21.2 28.0 30.0 32.0 34.0
400-1000 24.8 31.0 32.0 34.0 36.0
Super Power-Wedge 5V 900-1800 7.1 8.5 9.5 10.0 11.0
900-1800 9.0 10.0 11.0 12.0 13.0
900-1800 14.0 12.0 13.0 14.0 15.0
700-1200 21.2 14.0 15.0 16.0 17.0
8V 900-1800 12.5 18.0 21.0 23.0 25.0
900-1800 14.0 21.0 23.0 24.0 28.0
700-1500 17.0 24.0 26.0 28.0 30.0
700-1200 21.2 28.0 30.0 32.0 34.0
400-1000 24.8 31.0 32.0 34.0 36.0
V-BELT TENSIONING (Continued)
USE OF TABLES
(NOTE: For banded V-Belts, Use the Elongation Method)
STEP 1
Install the belts per rules 1 and 2 of the “General Method” discussed previously. Measure span length (t) in inches, or calculate per “Formula Method”.
STEP 2
Calculate the deflection distance by t/64 = deflection.
STEP 3
Depending on the belt type and cross section, and the small sheave diameter and speed, locate the Minimum Deflection Force (Pmin) in the appropriate drive ratio column of Table 33 on Page 9. For intermediate diameters or ratios, use interpolation.
Maximum Deflection Force = 1.5 x minimum (for new belts, 2.0 x Minimum can be used.)
STEP 4
Tension belts per Steps 5 & 6 of “Formula Method”. When using Carlisle Tensiometer (part no. 102761) see instructions on page 13.
ELONGATION METHOD
This method is recommended for tensioning Super Vee-Band, Wedge-Band and Gold Label Cog-Band drives where larger deflection forces make the use of other methods impractical.
Because belt elongation is related to the tension causing it, tape-measured lengths, both slack and tight, can be used to obtain proper Vee-Band tension.
VEE-BAND INSTALLATION AND TENSIONING PROCEDURE
STEP 1
Check sheaves to make sure they are properly aligned and that the grooves are not excessively worn (they should not be dished out more than 1/64”).
STEP 2
Decrease the center distance until the Vee-Band(s) can be easily slipped into the sheave grooves. Forcing the belts on can damage the load-carrying cords and cause premature failure.
STEP 3
With the Vee-Band(s) still on the drive at no tension,tape their outside circumference (slack O.C.).
NOTE: If you are tensioning a used belt, decrease the center distance until there is no tension on it; then tape the outside circumference.
V-BELT TENSIONING (Continued)
STEP 4
Find the required static tension (Ts) per individual strand (rib) using the formula: Design HP x K
Ts = Q x S + Tc
D-d
Where: K = value from table 29 on Page 287 depending on
C
Q = number of belts S = belt speed, fpm/1000 Tc = add-on tension allowance for centrifugal force (See Table 32)
STEP 5
Find a range of recommended Static Strand Tensions:
Lower value = Ts (from Step 4)
Upper value = 1.5 x Ts
STEP 6
Calculate minimum and maximum elongation band lengths for use in tensioning drive:
a.
From table 34, find length multipliers corresponding to the lower and upper values of Ts in Step 5.
b.
Multiply the slack O.C. found in Step 3 by the multipliers to find the minimum and maximum elongated band lengths.
STEP 7
Increase the drive center distance until a tape measurement of the band(s) O.C. is between the two values calculated for elongated band lengths in Step 6(b).
STEP 8
Re-tension as required. A new Vee-Band may lose tension rapidly during the run-in period and will probably need re-tensioning. A Vee-Band that has been on a drive for some time may also require re-tensioning due to tension decay from normal use and wear.
V-BELT TENSIONING (Continued)
TABLE 34 BELT LENGTH MULTIPLIERS FOR TENSIONING BANDED V-BELTS BY THE ELONGATION METHOD
Ts Per Strand (lbs.) Wedge-Band Super Vee-Band Gold Label Cog-Band
R3VX All R5V R8V RBP RCP RDP RBX RCX RCX RDX
R5XV R5V R8VX R8V RBP144 & under over RBP144 RCP144 & under over RCP144 All All up thru RBX210 over CX210 All
10 12 14 16 18 1.0012 1.0014 1.0016 1.0019 1.0021 1.0007 1.0009 1.0010 1.0011 1.0013 1.0006 1.0008 1.0009 1.0010 1.0012 1.0003 1.0004 1.0004 1.0005 1.0005 1.0007 1.0009 1.0010 1.0011 1.0013 1.0006 1.0008 1.0009 1.0010 1.0012 1.0007 1.0009 1.0011 1.0012 1.0014 1.0005 1.0006 1.0007 1.0008 1.0009 1.0007 1.0008 1.0009 1.0011 1.0012 1.0004 1.0005 1.0006 1.0007 1.0008 1.0006 1.0008 1.0009 1.0010 1.0012 1.0005 1.0006 1.0007 1.0008 1.0009 1.0008 1.0008 1.0011 1.0012 1.0014 1.0007 1.0008 1.0010 1.0011 1.0012
20 24 32 36 40 1.0023 1.0028 1.0038 1.0042 1.0047 1.0014 1.0017 1.0023 1.0026 1.0029 1.0013 1.0016 1.0021 1.0023 1.0026 1.0006 1.0007 1.0009 1.0011 1.0012 1.0014 1.0017 1.0022 1.0025 1.0028 1.0013 1.0016 1.0021 1.0024 1.0026 1.0016 1.0019 1.0027 1.0031 1.0035 1.0010 1.0012 1.0016 1.0018 1.0020 1.0013 1.0016 1.0021 1.0024 1.0026 1.0009 1.0010 1.0014 1.0016 1.0017 1.0003 1.0015 1.0021 1.0023 1.0026 1.0010 1.0012 1.0015 1.0017 1.0019 1.0015 1.0018 1.0024 1.0026 1.0029 1.0014 1.0017 1.0022 1.0024 1.0027
45 50 55 60 65 1.0053 1.0060 1.0066 1.0072 1.0079 1.0032 1.0036 1.0039 1.0043 1.0047 1.0029 1.0033 1.0036 1.0039 1.0043 1.0013 1.0015 1.0016 1.0018 1.0019 1.0031 1.0034 1.0037 1.0040 1.0044 1.0030 1.0033 1.0036 1.0040 1.0043 1.0040 1.0046 1.0052 1.0058 1.0064 1.0023 1.0025 100.28 1.0030 1.0033 1.0030 1.0033 1.0036 1.0039 1.0043 1.0019 1.0022 1.0024 1.0026 1.0028 1.0029 1.0032 1.0036 1.0039 1.0042 1.0022 1.0024 1.0027 1.0029 1.0032 1.0033 1.0036 1.0039 1.0043 1.0046 1.0030 1.0033 1.0037 1.0040 1.0043
70 75 80 85 90 1.0085 1.0092 1.0098 1.0105 1.0111 1.0050 1.0054 1.0058 1.0061 1.0065 1.0046 1.0049 1.0053 1.0056 1.0060 1.0021 1.0022 1.0024 1.0025 1.0027 1.0047 1.0050 1.0053 1.0056 1.0059 1.0047 1.0050 1.0054 1.0057 1.0061 1.0071 1.0077 1.0084 1.0092 1.0099 1.0035 1.0038 1.0040 1.0043 1.0045 1.0046 1.0049 1.0052 1.0055 10..58 1.0031 1.0033 1.0035 1.0037 1.0040 1.0046 1.0049 1.0052 1.0056 1.0059 1.0035 1.0037 1.0040 1.0042 1.0045 1.0049 1.0053 1.0056 1.0059 1.0062 1.0046 1.0049 1.0052 1.0055 1.0058
95 100 120 140 160 1.0118 1.0125 1.0152 1.0181 1.0210 1.0069 1.0072 1.0087 1.0102 1.0117 1.0063 1.0066 1.0080 1.0094 1.0109 1.0028 1.0030 1.0035 1.0041 1.0047 1.0062 1.0065 1.0076 1.0087 1.0097 1.0065 1.0068 1.0083 1.0098 1.0113 1.0106 1.0114 1.0147 1.0183 1.0221 1.0048 1.0050 1.0061 1.0071 1.0082 1.0062 1.0065 1.0077 1.0090 1.0102 1.0042 1.0044 1.0053 1.0063 1.0072 1.0062 1.0066 1.0079 1.0093 1.0107 1.0048 1.0050 1.0061 1.0072 1.0083 1.0065 1.0068 1.0080 1.0091 1.0102 1.0060 1.0063 1.0074 1.0085 1.0095
180 200 240 280 320 1.0240 1.0271 10.336 1.0404 1.0475 1.0133 1.0148 1.0179 1.0211 1.0243 1.0123 1.0138 1.0168 1.0198 1.0229 1.0053 1.0059 1.0071 1.0083 1.0095 1.0107 1.0116 1.0134 1.0150 1.0165 1.0129 1.0145 1.078 1.0213 1.0249 1.0263 1.0307 1.0402 1.0505 - 1.0092 1.0103 1.0125 1.0149 1.0174 1.0114 1.0126 1.0150 1.0174 1.0198 1.0082 1.0092 1.0112 1.0132 1.0153 1.0121 1.0136 1.0165 1.0195 1.0225 1.0094 1.0106 1.0129 1.0154 10.179 1.0112 1.0122 1.0140 1.0158 1.0174 1.0104 1.0114 1.0131 1.0146 1.0161
360 400 450 500 550 1.0550 ---- 1.0276 1.0309 1.0351 1.0394 1.0438 1.0261 1.0294 1.0366 1.0379 1.0423 1.0106 1.0118 1.0133 10.148 1.0163 1.0179 1.0193 1.0209 1.0224 1.0240 1.0286 1.0325 1.0375 1.0428 1.0482 ----- 1.0200 1.0228 1.0266 1.0307 1.0352 1.0222 1.0246 1.0277 1.0309 1.0343 1.0175 1.0197 10.226 1.0255 1.0285 1.0256 1.0288 1.0329 1.0370 1.0413 1.0206 1.0233 10.268 1.0304 1.0342 1.0190 1.0206 1.0226 1.0247 1.0269 1.0175 1.0187 1.0202 1.0217 1,9231
600 650 700 750 800 ----- 1.0482 1.0528 --- 1.0468 1.0513 --- 1.0177 1.0192 1.0207 1.0222 1.0237 1.0256 1.0273 1.0291 1.0311 1.033 1.0539 ---- ----- 1.0401 1.0455 1.0514 -- 1.0377 1.0414 1.0452 1.0493 1.0536 1.0316 1.0348 1.0381 1.0414 1.0449 1.0457 1.0501 --- 1.0381 1.0421 1.0463 1.0506 - 1.0293 1.0320 1.0350 1.0384 1.0423 1.0246 1.0261 1.0277 1.0294 1.0313
850 900 950 1000 ---- ---- ---- 1.0251 1.0266 1.0281 1.0296 1.0357 1.0384 .10414 1.0448 ---- ---- ---- ---- 1.0484 1.0520 -- ---- ---- 1.0466 1.0516 -- 1.0334 1.0358 1.0385 1.0414
INSTRUCTIONS FOR USING THE SPRING LOADED V-BELT TENSIOMETER
Procedure for using the Carlisle V-Belt Tensiometer
1. Measure the span length of the drive. (See Figure 27). Set the large “O” ring at 1/64. for each inch of belt span. For example, set the large “O” ring 1/4. for a span length of 16., at 1/2. for a span length of 32., at 1. for a span length of 64. etc.
2. Set the small “O” ring at zero and press down the Carlisle Tensiometer at the center of the belt span (See Figure 28).
a. On a single belt drive, depress the Tensiometer until the large “O” ring is even with the bottom of a straight edge placed on the outside rims of the two sheaves.
b.
On a multiple belt drive, depress the Tensiometer until the large “O” ring is even with the top of the next belt. Measure each belt in the drive. and take the average reading of all belt tensions.
3.
Remove the Tensiometer, and observe that the small “O” ring has moved from its original setting at zero to the number of pounds required to deflect the belt.
4.
Check this reading against the value of Pmin and Pmax calculated using the table of Average Tensioning (page 9).
2-( D-d )2 h =t
t =
2
C64
Where: t = Span length, inches C = Center distance, inches D = Larger sheave diameter d = Smaller sheave diameter, inches
*Deflection height h = 1/64 per inch of span
