CHAPTER VJII. 

 TESTING OPERATIONS (Continued). 



TESTS OF ROPES, WIRE TESTS, TESTS UNDER 



VARIOUS TEMPERATURES, HARDNESS TESTS, 



AND TESTS OF CHAINS. 



134. Tension Tests of Wire Ropes. The arrangement of 

 the wires in a rope varies greatly, according to the use to 

 which the rope is to be put. Generally speaking, a 

 aumber of wires are twisted together so as to form a strand, 

 and a number of these strands are again laid together so 

 as to make up the whole rope. The simplest arrangement 

 of the wires is to have six placed symmetrically around 

 a central wire of the same size. This is shown on Fig. 121. 

 In some strands a second ring of wires is arranged on 



FIG. 121. Section of 49- Wire Rope. 



the outside of the existing seven. The central wire, 

 or core, of a strand is sometimes composed of similar metal 

 to that of the other wires. More frequently this central 

 wire is of very soft metal, while the others are harder. 

 When this is the case, the central wire is not regarded 

 as adding anything to the strength of the rope, but simply 

 acting as a core upon which to build the strand. The 

 reason for doing this is that on account of its position this 



