| Diam. of Rope Inches | Ultimate Strength, Lb. | Working Strength, Lbs. | ||
|---|---|---|---|---|
| Cotton | Manila Hemp | Cotton | Manila Hemp | |
| ½ | 1,150 | 1,900 | 50 | 50 |
| ⅝ | 1,800 | 2,900 | 78 | 78 |
| ¾ | 2,600 | 4,100 | 112 | 112 |
| ⅞ | 3,500 | 5,500 | 153 | 153 |
| 1 | 4,600 | 7,100 | 200 | 200 |
| 1¼ | 7,200 | 10,900 | 312 | 312 |
| 1½ | 10,400 | 15,000 | 450 | 450 |
| 1¾ | 14,000 | 19,800 | 612 | 612 |
| 2 | 18,400 | 25,100 | 800 | 800 |
STRENGTH OF MANILA ROPE
| Diam. of Rope in Inches | Average Quality New Manila Rope |
|---|---|
| 2 3⁄4 | 26 |
| 2 1⁄2 | 21 1⁄2 |
| 2 1⁄4 | 18 1⁄2 |
| 2 | 15 |
| 1 3⁄4 | 12 1⁄2 |
| 1 5⁄8 | 10 |
| 1 1⁄2 | 8 1⁄2 |
| 1 3⁄8 | 7 1⁄2 |
| 1 1⁄4 | 6 1⁄4 |
| 1 1⁄8 | 5 1⁄4 |
| 1 | 4 |
| 7⁄8 | 3 1⁄4 |
| 3⁄4 | 2 1⁄4 |
| 5⁄8 | 2 |
| 9⁄16 | 1 1⁄2 |
| 1⁄2 | 1 1⁄5 |
| 7⁄16 | 3⁄4 |
| 3⁄8 | 1⁄2 |
| 5⁄16 | 3⁄8 |
| 9⁄32 | 3⁄10 |
| 1⁄4 | 1⁄4 |
STEEL CABLES
The modern demands of industry for speed and large capacity have called for strengths exceeding that possible to attain from hemp or manila ropes, which are not excessive in size or cost. As a result, steel ropes and cables have been developed and perfected to a high degree of strength and dependability. The majority of hoists and cranes use steel rope. Logging industries depend for most part on steel cables. Cable cars use special steel cables which in many cases are several miles long. Long tramways use light steel cables, for long spans where manila rope would scarcely maintain its own weight. High speed passenger elevators maintain safe and dependable service day after day only through the strength of the perfected flexible steel cable. However, as stated above, each particular type of service calls for some special type of cable. The following tables are not complete but will serve to indicate the scope of the field covered by this subject.
CAST STEEL ROPE
Composed of 6 strands and a hemp center, 7 wires to the strand
| Diameter in Inches | Approximate Circumference in Inches | Approx. Breaking Strain in Tons of 2000 lbs. | Proper Working Load in Tons of 2000 lbs. | Minimum Size of Drum or Sheave in ft. |
|---|---|---|---|---|
| 1 1⁄2 | 4 3⁄4 | 63 | 12.6 | 11 |
| 1 3⁄8 | 4 1⁄4 | 53 | 10.6 | 10 |
| 1 1⁄4 | 4 | 46 | 9.2 | 9 |
| 1 1⁄8 | 3 1⁄2 | 37 | 7.4 | 8 |
| 1 | 3 | 31 | 6.2 | 7 |
| 7⁄8 | 2 3⁄4 | 24 | 4.8 | 6 |
| 3⁄4 | 2 1⁄4 | 18.6 | 3.7 | 5 |
| 11⁄16 | 2 1⁄8 | 15.4 | 3.1 | 4 3⁄4 |
| 5⁄8 | 2 | 13 | 2.6 | 4 1⁄2 |
| 9⁄16 | 1 3⁄4 | 10 | 2 | 4 |
| 1⁄2 | 1 1⁄2 | 7.7 | 1.54 | 3 1⁄2 |
| 7⁄16 | 1 1⁄4 | 5.5 | 1.10 | 3 |
| 3⁄8 | 1 1⁄8 | 4.6 | .92 | 2 3⁄4 |
| 5⁄16 | 1 | 3.5 | .70 | 2 1⁄4 |
| 9⁄32 | 7⁄8 | 2.5 | .50 | 1 3⁄4 |