7,000 lbs Poly - Yarn PSI Max Effective Contact With Bow Shackles.75% - ECW 3 ¼ " SPA v/s FTO 3 SWL 8,400 lbs E = 2" ECW DIA. SQ X.75 = 1.13 LOAD 8,400 lbs divide 1.13 = 7, lbs = NO 7/8" SPA v/s FTO 3 SWL 8,400 lbs E = 2.28" ECW DIA. SQ X.875 = 1.50 LOAD 8,400 lbs divide 1.50 = 5,600 lbs = YES 2" SPA v/s FT010 SWL 66,000 lbs E = 5.75" ECW DIA. SQ X 2 = 8.64 LOAD 66,000 lbs divide 8.64 = 7, lbs = NO 2" SPA v/s FHPZ60 SWL 60,000 lbs. = E = 5.25 Underload = 4' = Yes Note: High performance sling shall not exceed E dimension under load
Strength Loss of Wire Rope Over Stationary Sheaves or PinsRope breaking strength is determined in a standard test wherein fittings are attached to the ends of the rope and the rope is pulled in a straight line. If, however, the rope passes over a curved surface (such as a sheave or pin) its strength "is decreased." The amount of such reduction will depend on the severity of the bend as expressed by the D/d ratio. For example, a rope bent around a pin of its own diameter will have only 50% of the strength attributed to it in the standard test. This is called "50% efficiency" (Fig. 38). Even at D/d ratios of 40, there may be a loss of up to 5%. At smaller D/d ratios, the loss in strength increases quite rapidly. The angle of bend need not be 180º, 90º, or even 45º; relatively small bends can cause considerable loss. All discussion of strength pre-supposes a gradually applied load not to exceed one inch per minute.