TM5-3810-305-10break at that time, there is no need for con-cern. On the other hand, should more wiresbreak, the cause should be carefully investi-gated.On any installation, valley breaks - i.e.,where the wire ruptures between strands -should be given serious attention. When twoor more such conditions are found, the ropeshould be replaced immediately.It is well to remember that once broken wiresappear - in a normal rope operating undernormal conditions - a good many more willshow up within a relatively short period.Attempting to squeeze to the last measure ofservice from a rope beyond the allowablenumber of broken wires (Table 7) will createan intolerably hazardous situation.A diagnostic guide to some of the mostprevalent rope abuses is given in Table 8. Onthe following pages these abuses are illus-trated and described.A wire that has broken under a tensile load inexcess of its strength is recognized by the“cup and cone” configuration at the fracturepoint (A, Figure 4-43). The necking down ofthe wire at point of failure shows that failureoccurred while the wire retained its ductility.A fatigue break is usually characterized bysquared-off ends perpendicular to the wireeither straight across or Z-shaped (B) and(c).PEENINGABRASIONFigure 4-42. Effects of Abrasion and PeeningFigure 4-43. Types of Breaks in Wire Rope4-49
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