Machinery's Handbook, 31st Edition
Transmission Roller Chains 2625 Proportions of Sprockets.— Typical proportions of single-strand and multiple-strand cast roller chain sprockets, as provided by the American Chain Association, are shown in Table 7. Typical proportions of roller chain bar-steel sprockets, also provided by this association, are shown in Table 8. Table 7. Typical Proportions of Single-Strand and Multiple-Strand Cast Roller Chain Sprockets
E
C ”
C
C
F R
E
T
C
DHD H T R C ” C
C
C ”
C ”
T
T
H L HD L D H
L D H
R
R
T
T
R
R
H
h
HD
HD
L
L
LM
DHD
HD
Above 80 teeth pitch and up 3 4 pitch Up to 80 teeth , 3 8 , 1 2 5 8
Single-Strand
Multiple-Strand
Sprocket Web Thickness, T , for Various Pitches P
Single-Strand Multiple-Strand PTPTPTPTPTP T P TPT 3 ∕ 8 .312 3 ∕ 4 .437 1 1 ∕ 2 .625 2 1 ∕ 4 1.000 3 ∕ 8 .375 3 ∕ 4 .500 1 1 ∕ 2 .750 2 1 ∕ 4 1.125 1 ∕ 2 .375 1 .500 1 3 ∕ 4 .750 2 1 ∕ 2 1.125 1 ∕ 2 .406 1 .562 1 3 ∕ 4 .875 2 1 ∕ 2 1.250 5 ∕ 8 .406 1 1 ∕ 4 .562 2 .875 3 1.250 5 ∕ 8 .437 1 1 ∕ 4 .625 2 1.000 3 1.500 Formulas for Dimensions of Single and Multiple Sprockets H = 0.375 + D 6 + 0.01 PD E = 0.625 P + 0.93 W F = 0.150 + 0.25 P L = 4 H for semi-steel castings G = 2 T C = 0.5 P R = 0.4 P for single-strand sprockets C ′ = 0.9 P R = 0.5 T for multiple-strand sprockets All dimensions in inches. Where P = chain pitch and W = nominal chain width. Table 8. Typical Proportions of Roller Chain Bar-steel Sprockets
H = Z + D /6 + 0.01 PD For PD up to 2 inches, Z = 0.125 inch; for 2-4 inches, Z = 0.187 inch; for 4-6 inches, 0.25 inch; and for over 6 inches, 0.375 inch. Hub length L = 3.3 H , normally, with a minimum of 2.6 H . Hub diameter HD = D + 2 H , but not more than the maximum hub diameter MHD given by the formula: . cot MHD P N 180 1 0030 ° = − − a k where P = Chain pitch, in inches; N = Number of sprocket teeth
HD
PD
D D
L
When sprocket wheels are designed with spokes, the usual assumptions made in order to determine suitable proportions are as follows: 1) that the maximum torque load acting on a sprocket is the chain tensile strength times the sprocket pitch radius; 2) that the torque load is equally divided between the arms by the rim; and 3) that each arm acts as a canti lever beam. The arms are generally elliptical in cross section, the major axis twice the minor axis.
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