404 Molesworth’s pocket-book
Torsional Moment op Resistance for Shafts.
(E. J. Edwards.)
' TT
Calculated from the formula M = —- f d%.
16
1
co
pi
i m
$ .S
.8
§
M = Movement of resistance to torsion, tt = 3-14159.
/ = Stress per square inch, d = Diameter of shaft in inches.
= 8000 to 10,u00 lbs. for wrought iron, and 4000 to
5000 lbs. for cast iron.
Dia- meter. /= soso ;/= loooo lbs. lbs. Dia- meter. / = S0()0 11». /= 1O003 lbs,
inches. 1 1,570 1,962 inches, n 598,293 747,866
li 3,066 3,832 n 662,344 827,930
11 5,299 6,624 n 730,810 913,512
u 8,414 10,517 8 803,840 1,004,800
2 12,560 15,TOO 8i 964,176 1,205,220
2i 17,883 22,354 9 1,144,530 1,430,062
2i 24,5311 30,664 91 1,316,079 1,682,599
2i 32,6511 40,814 10 ],570,000 1,962,500
3 42,390 52,988 10} 1,817,471 2,271,839
3i 53,895 67,369 11 2,089,R70 2,612,088
3i 67,314 84,143 Hi 2,387,774 2,984,717
3f 82,793 103,491 12 2,712,960 3,391 ,'2i'O
4 100,480 125,600 13 3,449,290 4,311,612
4| 120,522 150,652 143,066 178,833 14 4,308,080 5,385,160
44 15 5,298,750 6,623,438
4< 168,260 210,325 16 6,430,720 8,038,400
5 196,250 245,313 17 7,713,410 9,641,762
6$ 227,184 233,980 18 9,156,240 11,445,300
5i 261,209 326,511 19 10,768,630 13,460,788
5J 298,472 373,090 20 12,560,000 15,700,000
6 339,120 423,900 21 14,539,770 18,174,710
6i 383,300 479,125 22 16,717,360 20,896,700
431,161 538,951 23 19,102,190 23,877,738
6| 482,8481603,560 21 21,703,680 27,129,600
7 i538,510 673,138
■2
2
8
o
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Erample —Ilequired to find a shaft for a drum having 2$ tons pulling ou it
at 17" radius and taking/= 8000 lbs. .
The moment of weight = WI = 2i X 2240 X 17 - 95,200 inch-lbs ; the
torsional moment of resistance must be equal or greater than this amount.
Find in the table the number next higher, which in this case is 100,480 oppo-
Bite 4" diameter which will be the size of shaft required in wrought iron.
If for cast-irun ehaft and j i 4bOU lbs., theu 6" diameter is the size, since
~ = 98125.