Page 233 - Industrial Power Engineering and Applications Handbook

8/212 Industrial Power Engineering and Applications Handbook
Table 8.7 Arc of contact correction factors [flat and V-belts] Table 8.8 Recommended standard pulley and outside
diameters
Arc of contact on Correction factor, ;.e.
__ smaller pulley proportion oj 180" Outside diameter
D-d
C
(degrees) rating
Belt section A B C D E
Pitch mm mm mm mm mm
0.00 180 1 .OO
0.05 177 0.99 diamete? (mm)
0.10 174 0.99 75 81.6
0.15 171 0.98 80 86.6
0.20 169 0.97 85 91.6
0.25 166 0.97 90 96.6
0.30 163 0.96 95 101.6
0.35 160 0.95
0.40 157 0.94 100 106.6
0.45 154 0.93 106 112.6
0.50 151 0.93 112 118.6
0.55 148 0.92 118 124.6
0.60 145 0.91 125 131.6 133.4
0.65 142 0.90 132 138.6 140.4
0.70 139 0.89 140 146.6 148.4
0.75 136 0.88 150 156.6 15X.4
0.80 133 0.87 160 166.6 168.4
0.85 130 0.86 I70 178.4
0.90 127 0.85 I80 186.6 188.4
0.95 123 0.83 190 198.4
1 .OO 120 0.82
200 206.6 208.4 211.4
212 220.4 223.4
57.3( D - d) 224 232.4 235.4
Note Arc of contact with smaller pulley = 180" -
C 236 244.4 247.4
where C is the centre distance (mm) 250 256.6 258.4 261.4
D is the pitch diameter of larger pulley (mm) Figure 265 276.4
d is the pitch diameter of smaller pulley (mm) 1 Or 280 288.4 291.4
315 321.6 323.4 326.4
355 362.4 366.4 371.2
375 391.2
400 406.6 408.4 411.4 416.2
where 425 441.2
K =belt factor, 2 to 2.5 for V-belts and 2.5 to 3 for 450 461.4 466.2
flat belts. Sometimes it may be higher (up to 4 to 475 491.2
5). (The higher values must be considered when 500 506.6 508.4 511.4 516.2
the distance between shafts is short or belt tension 530 546.2
is high). 560 571.4 576.2
D = diameter of pulley on the motor (m) 630 636.6 638.4 641.4 646.2
I =half of the pulley width (load distance) (m) 710 726.2
W =weight of complete rotor and driven masses on 800 806.6 808.4 811.4 816.2
916.2
900
the motor shaft, such as the pulley and the belts 1000 1006.6 1008.4 1011.4 1016.2
(k&)
'+' applicable when the belt pull is downwards 1250 1258.4 1261.4 1266.2
1616.2
1600
[vertical drives, Figure 8.13(a)] and 2000 2016.2
'-' applicable when the belt pull is upwards [vertical
drives, Figure 8.13(b)]. aThe limits of tolerances on the pitch diameter will be k 0.8%
'0' when the shaft is horizontal or the drive and the Courtesy Goodyear. See also IS 3142 and IS0 4183
driven equipment are in the same horizontal plane
and in line with each other.
0 Axial forces or thrust load
The allowable pulley loads for standard motors are When these exist they can be expressed by
given in Table 8.10. These are recommended by a few Pa (for horizontal motors) =axial force of pump,
manufacturers for their motors, but they are generally turbine or any other
true for other motors also. load (kg)
0 The bending moment at the weakest section of the Pa (for vertical motors) = axial force as above +
shaft, i.e. at the collar of the DE shaft (Figure 8.14). weight of complete rotor
K. 973. kW and driven masses on the
B.M. = P, .I = .I mkg motor shaft such as the
D
Nr '7 pulley and the belts (kg.)
L