Page 227 - Industrial Power Engineering and Applications Handbook

Transmission of load and suitability of bearings 8/207

Figure 8.11 Selection of cross-section for V-belts

for an average 14 hourdday, then the SF according to where
Table 8.5 = 1.3 L = belt pitch length (mm)
C = centre distance between the two pulleys (mm).
and design power = 11 0 x 1.3 D = pitch diameter of the larger pulley (mm)
= 143 kW d = pitch diameter of the smaller (faster) pulley (mm)
Calculate the speed ratio of the faster shaft to the slower :. L = 2 x 1000 + 1.57(475 + 400) + (475 - 400)'
shaft 4 x I000
980
= - 1.19 = 2000 + 1373.75 + 1.406
=
825
= 3375.16 mm.
Pitch dia. of larger pulley
This is the same as We show the nominal inside length for various standard
Pitch dia. of smaller pulley sections of belts in Table 8.9. According to the table the
Select the belt cross-section nearest standard belt available has a pitch length of 3330
Use the selection curves provided by the manufacturer or 3736 mm. For a more closer length of belt, either change
(which are almost the same for all manufacturers) (see the pulley size or select another make of belt or have it
Figure 8.1 1). For a design power of 143 kW to be transmitted made to order. But a length of 3330 seems reasonable,
at 980 r.p.m., the recommended cross-section of belts hence it is accepted.
according to these curves is identified as D.
Select the pulley diameter :. L=3330 mm
Refer to the manufacturer's catalogue for the recommended The centre distance will now be less than 1 m and can be
pulley pitch and outside diameters. These data are provided
in Table 8.8 for a leading manufacturer. calculated by
Consider small pulley of d = 400 mm C=A+JZ
Then the larger pulley D = 400 x 1.19
where A = - n(D+ d)
= 476 mm 4 8
(D - d)'
The nearest standard size available is 475 mm which is and 6=
acceptable. ~ 8
Determine the belt pitch length (These formulae are available in the product catalogues
The pitch length of a belt is its circumferential length at of all leading manufacturers.)
the pitch width of the belt. The pitch width of a belt is
shown in Figure 8.12, and is provided by manufacturers ... A = - (475 + 400)
LL
-
3330
as standard data. It can be calculated by 4 8
= 832.5 - 343.44
(D- d)'
L=2C+l,57(D+d)+- (8.2) = 489.06
4c