Machinery's Handbook, 31st Edition
COUPLINGS and Clutches 2523 For small sizes and low power applications, a setscrew may provide the connection be- tween the hub and the shaft, but higher power usually requires a key and perhaps two setscrews, one of them above the key. A flat on the shaft and some means of locking the setscrew(s) in position are advisable. In the AGMA Class I and II fits, the shaft tolerances are −0.0005 inch from 1 ⁄ 2 to 1 1 ⁄ 2 inches diameter and −0.001 inch on larger diameters up to 7 inches. Class I coupling bore tolerances are + 0.001 inch up to 1 1 ⁄ 2 inches diameter, then + 0.0015 inch to 7 inches diameter. Class II coupling bore tolerances are + 0.002 inch on sizes up to 3 inches diameter, + 0.003 inch on sizes from 3 1 ⁄ 4 through 3 3 ⁄ 4 inches diameter, and + 0.004 inch on larger diameters up to 7 inches. Interference Fits.— Components of couplings transmitting over 150 horsepower often are made with an interference fit on the shafts, which may reduce fretting corrosion. These couplings may or may not use keys, depending on the degree of interference. Keys may range in size from 1 ⁄ 8 inch wide by 1 ⁄ 16 inch high for 1 ⁄ 2 -inch diameter shafts to 1 3 ⁄ 4 inches wide by 7 ⁄ 8 inch high for 7-inch diameter shafts. Couplings transmitting high torque or operating at high speeds or both may use two keys. Keys must be a good fit in their key - ways to ensure good transmission of torque and prevent failure. AGMA standards provide recommendations for square parallel, rectangular section, and plain tapered keys, for shafts of 5 ⁄ 16 through 7 inches diameter, in three classes designated commercial, preci- sion, and fitted. These standards also cover keyway offset, lead, parallelism, finish and radii, and face keys and splines. (See also ANSI and other Standards in KEYS AND KEY- SEATS starting on page 2539 of this Handbook.) Double-Cone Clamping Couplings.— As shown in the table, double-cone clamping cou plings are made in a range of sizes for shafts from 1 7 ⁄ 16 to 6 inches in diameter, and are easily assembled to shafts. These couplings provide an interference fit, but they usually cost more and have larger overall dimensions than regular flanged couplings. Double-cone Clamping Couplings
G G K
F
M
J
E
C
D
H
A
B
” 1 4
” 1 4
L
No. of Bolts
No. of Keys
ABCDEFGHJKLM
1 5
3 3 3 3 4 4 4 4 4 4
1 1 1 1 1 1 1 1 1 2
1 7 ∕ 16
5 1 ∕ 4
2 3 ∕ 4 3 1 ∕ 2 4 5 ∕ 16
2 1 ∕ 8 2 7 ∕ 8 3 5 ∕ 8 5 3 ∕ 8 5 1 ∕ 2 6 7 ∕ 8 7 1 ∕ 4 7 3 ∕ 4 8 1 ∕ 4
1 5 ∕ 8 2 1 ∕ 8
2 1 ∕ 8 2 3 ∕ 4 3 1 ∕ 2
4 3 ∕ 4 6 1 ∕ 4
1 1 ∕ 8 1 1 ∕ 8 1 7 ∕ 8 2 1 ∕ 4 2 5 ∕ 8 3 3 ∕ 4 3 3 ∕ 4 3 3 ∕ 4 3 3 ∕ 4 3 3 ∕ 4
5 ∕ 8 5 ∕ 8 3 ∕ 4 3 ∕ 4 7 ∕ 8 7 ∕ 8 7 ∕ 8 7 ∕ 8
1 ∕ 2
1 15 ∕ 16 7
1 3 ∕ 8 1 3 ∕ 4 2 1 ∕ 8 2 1 ∕ 2 2 3 ∕ 4 2
6 1 ∕ 4 1 ∕ 2 7 7 ∕ 8 5 ∕ 8 9 1 ∕ 2 5 ∕ 8
3
2 7 ∕ 16
8 3 ∕ 4
7 13 ∕ 16
4 3 ∕ 16 9 5 1 ∕ 16 11 1 ∕ 4
3
10 1 ∕ 2 5 1 ∕ 2 12 1 ∕ 4 7 14 7 15 1 ∕ 2 8 17 9 17 1 ∕ 2 9 1 ∕ 2 18 10
4 3 ∕ 32 3 1 ∕ 2
3 1 ∕ 2
4 3 ∕ 8 4 3 ∕ 4 5 1 ∕ 4 5 3 ∕ 4 6 1 ∕ 4 6 3 ∕ 4
11 1 ∕ 4 3 ∕ 4
12
12
4
5 1 ∕ 2 6 3 ∕ 4
3 ∕ 4
4 1 ∕ 2
13 1 ∕ 2
14 1 ∕ 2 3 ∕ 4 15 1 ∕ 4 3 ∕ 4 15 1 ∕ 4 7 ∕ 8 15 1 ∕ 4 7 ∕ 8
7 7 7
15
3 3 3
5
1 1
5 1 ∕ 2
15 1 ∕ 2
16
6
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