the wire rope before any evidence is visible on the outside. This 

 has been found to be the result of a lubricating practice which has 

 been adequate to keep the outside of the rope coated but has been 

 insufficient to prevent the loss of the original lubricant from in- 

 side the cable and has permitted moisture to penetrate it. 



Ab 



rasion 



Abrasion and other forms of wear generally appear to pro- 

 gress very rapidly on a new rope, since only a small surface of 

 the wires is exposed to abrading objects. However, as worn sur- 

 faces develop on the wire crowns, the wear is distributed over a 

 larger area of contact and the apparent rate of abrasion decreases. 

 On regular lay ropes , the wearing action causes a loss of metal 

 from the crowns of the outside wires and small, elliptical flat 

 surfaces develop. 



A constant contributor to wear is the peening action produced 

 when the wire rope is subjected to short, sharp blows against sta- 

 tionary or moving objects such as small track rollers on a ship. 

 This type of abuse causes some loss of metal from the wires, but 

 its principal damage is the deformation of their original circular 

 shape. 



The speed with which the wire rope is handled is a very im- 

 portant factor in its wearing qualities. Any section of rope oper- 

 ating over a sheave makes two complete bends (one when it con- 

 forms to the sheave groove and another when straightened). These 

 changes in curvature require rapid movement of the wires and 

 strands, and materially influence their bending fatigue. 



In general, the safety of a working load is determined by the 

 same conditions which contribute to abrasion and corrosion: the 

 weight of the applied load, the speed of operation and of accelera- 

 tion and deceleration, the length of the wire rope used, and the 

 number, size, and location of sheaves and drums. 



