Machinery's Handbook, 31st Edition
2594 V-Ribbed Belts Belt Size Designation: Belt sizes are identified by a standard belt number, which consists of belt effective length to the nearest tenth of an inch, a letter designating cross section, and the number of ribs. For example, 540L6 signifies a 54.0 in. effective length, L belt, 6 ribs wide. Sheave Dimensions: Groove angles and dimensions for sheaves and face widths of sheaves for multiple belt drives are given in Table 26, along with various tolerance values. Cross Section Selection: Use the chart (Fig. 9) as a guide to the V-ribbed belt cross section for any combination of design horsepower and speed of the faster shaft. When the inter- section of the design horsepower and speed of the faster shaft falls near a line between two areas on the chart, the possibilities in both areas should be explored. Special circum stances (such as space limitations) may lead to a choice of belt cross section different from that indicated in the chart. H and K cross sections are not included because of their specialized use. Belt manufacturers should be contacted for specific data. 10,000
5,000 4,000 3,450 3,000 2,500 2,000 1,750 1,500 1,160 1,000
L
J
870 800 690 575 500 435 400 300 250 200 150 100
M
1
0.5
1
2 3 4 5 10 20 Design Horsepower (Horsepower × Service Factor)
50 100 200
500
Fig. 9. Selection of V-Ribbed Belt Cross Section Horsepower Ratings: The horsepower rating formulas are: . . . . d r d r d d r 01240 008663 02318 10 J: HP . p p 009 4 2 = − − + − ^ ^ h h ; E ×
r 008663 1 1 − ;
E
K
p
p
SR
. 05761 08987 1018 10 .
2
L: HP
×
4
.
.
r 08987 1 1 − ;
d r d r p ;
d r p
h
^
=
−
−
+
E
E
−
. 009
d
K
h
^
p
p
SR
. 1975 6597 3922 10 × In these equations, d p = pitch diameter of the small sheave, in.; r = rpm of the faster shaft divided by 1000; K SR = speed ratio factor given in the accompanying Table 30. These formulas give the maximum horsepower per rib recommended, corrected for the speed ratio. To obtain the horsepower per rib for an arc of contact other than 180 degrees, and for belts longer or shorter than the average length, multiply the horsepower obtained from these formulas by the length correction factor (Table 28) and the arc of contact correction factor (Table 29). . . . d r d r p ; d d r p r 6597 1 1 K M: HP . 009 p p SR 4 2 = − − + − − ^ ^ h h ; E E
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