Wire Rope Inspection - cont - TM-5-3810-305-10

Wire Rope Inspection - cont - TM-5-3810-305-10_109

Wire Rope Inspection - cont - TM-5-3810-305-10_111

TM-5-3810-305-10 Crane Wheel Mounted Hydraulic Light 7 1/2 Ton (Rough Terrain Crane) Model LRT 110 Manual
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TM5-3810-305-10 4. 5. 6. 7. Because criteria for removal are varied, and because diameter, in itself, is a vague crite- rion, the table of minimum diameters has been deliberately omitted from this manual. Corrosion: Corrosion, while difficult to evaluate, is a more serious cause of degrada- tion than abrasion. Usually, it signifies a lack of lubrication. Corrosion will often occur internally before there is any visible external evidence on the rope surface. Pitting of wires is a cause for immediate rope removal. Not only does it attack the metal wires, but it also prevents the rope’s component parts from moving smoothly as it is flexed. Usually, a slight discoloration because of rusting merely indicates a need for lubrication. Severe rusting, on the other hand, leads to premature fatigue failures in the wires, neces- sitating the rope’s immediate removal from service. When a rope shows more than one wire failure adjacent to a terminal fitting, it should be removed immediately. To retard corrosive deterioration, the rope should be kept well lubricated. In situations where extreme corrosive action can occur, it may be necessary to use galvanized wire rope. Kinks: Kinks are permanent distortions caused by loops drawn too tightly. Ropes with kinks must be removed from service. “Bird caging”: Bird caging results from tor- sional imbalance that comes about because of mistreatments such as sudden stops, the rope being pulled through tight sheaves, or wound on too small a drum. This is cause for rope replacement unless the affected portion can be removed. Localized conditions: Particular attention must be paid to wear to the equalizing sheaves. During normal operations this wear 8. 9. is not visible. Excessive vibration or whip can cause abrasion and/or fatigue. Drum crossover and flange point areas must be care- fully evaluated. All end fittings, including splices, should be examined for worn or broken wires, loose or damaged strands, cracked fittings, worn or distorted thimbles and tucks of strands. Heat Damage: After a fire or the presence of elevated temperatures, there may be metal discoloration or an apparent loss of internal lubrication; fiber core ropes are particularly vulnerable. Under these circumstances, the rope should be replaced. Protruding Core: If, for any cause, the rope core protrudes from an opening between the strands, the rope is unfit for service. 10. Damaged End Attachments: Cracked, bent, or broken end fittings must be eliminated. The cause should be sought out and cor- rected. In the case of bent hooks, the throat openings - measured at the narrowest point - should not exceed 15% over normal nor should twisting be greater than 10%. 4-47

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