Chap. XI.
MECHANICS.
947
Diameter inInches.
Diameter inInches.
Diameter inInches.
Diameter inInches.
Diameter inInches.
2
•237
•31
■44
*54
•62
4
•67
•88
1*24
1 *5
1-76
6
1*23
1-61
2-28
2-79
3 22
8
1*9
2-48
351
4-30
4-96
10
2-65
3-47
4-9
6 0
6-93
12
3-48
4-55
6-44
7-89
910
14
4*38
5-74
812
9*94
11-48
16
5-36
7*01
9-92
12-15
14 02
Own weightonly.
Stress equal toits own weight,or n = 1.
Stress double itsown weight,or n = 2.
Stress three timesits own weight,or n = 3.
Stress four timesits own weight,or n = 4.
When shafts of cast-iron are hollow, they will resist more twisting than solid ones con-taining the same quantity of metal, for circles are to each other as the squares of theirdiameters, and to compute the diameters of a hollow cylindrical shaft, where the thicknessof the metal is two-tenths of the entire diameter, which is found to be usually adopted inpractice ; the cube of the length in feet, multiplied by ‘009, and the product again mul-tiplied by the number of times the weight of the shaft is contained in the stress ; from thelatter product extract the square root, which will be the diameter in inches. It has beenfound that the square of the exterior diameter in inches, multiplied by 1*6 times the lengthin feet, gives nearly the weight of the shaft in pounds.
Hollow Shafts of Cast-Iron to resist lateral Stress , though it is necessary to consider Torsion
as well.
Length.
ExteriorDiameterin Inches.
InteriorDiameterin Inches.
KxteriorDiameterin Indies.
InteriorDiameterin Inches.
ExteriorDiameterin Inches.
InteriorDiameterin Inches.
ExteriorDiameterin Inches.
InteriorDiameterin Inches.
4
1 -5
0-9
1-9
1*1
2-2
1 3
2 4
1-4
6
28
1-6
3-5
2-1
4*0
2*4
4*5
2-7
8
4-3
2*5
5*3
3-1
6-1
3*6
69
4-1
10
6 0
3-6
7-4
4-4
8*5
5 0
95
5-7
12
7-9
4-7
9*8
5*8
112
6-7
12 6
7 *5
14
100 .
6 0
12-3
7*3
14-2
8-5
15*9
9*5
16
12*2
7*3
150
9 0
17-3
10-3
19*4
11-6
Stress four times theweight of the shaft.
Stress six times theweight of the shaft.
Stress eight times theweight of the shaft.
Stress ten times theweight of the shaft.
When the diameter of a shaft is found for cast-iron, by multiplying this diameter by ‘935,the product will give a diameter for a shaft of equal stiffness made of wrouglit-iron ; and ashaft of fir should be 1 *716 times the diameter of a cast-iron one, and of oak 1*83 times, inorder to be of equal stiffness.
Shafts of cast-iron to resist torsion may have their diameter, when cylindrical, accordingto the following table, which is found by dividing 240 times the number of horse-power bythe number of revolutions per minute, and extracting the cube root of the quotient for thediameter in inches.
Revolutions of the Shafts in a Minute.
Diameter ofShafts inInches.
5
10
20
30
40
50
2
Horse, power.0-17
Horse-power.0 33
Horse-power.
0-66
Horse-power.
0-99
Horse-power.
1-33
Horse-power.
1-66
3
0-56
1-13
2-25
3*37
4-5
5-62
4
1-33
2-66
5-33
7-99
10-66
13-33
5
2-6
52
10-4
15-6
20-8
26-0
6
4-5
9 0
18-CO
27-0
36 0
450
7
7'15
14-3
28-6
42-9
57-2
71 '5
8
10*66
21 -33
42-66
64 0
850
106-6
10
20-83
41-66
83-33
125 0
166 0
208 -3
12
36-00
720
144-0
216-0
288-0
3600
14
63-83
127-66
255-33
383 0
5100
638-3
16
85-33
170-66
341-33
512-0
682-0
853-3
3 p 2