The 636 Class of wire rope is characterized by the relatively large number of wires used in each strand. Ropes of this class are among the most flexible available due to the greater number of wires per strand, however their resistance to abrasion is less than ropes in the 619 Class.
The designation 636 is only nominal, as in the case with the 619 Class. Improvements in wire rope design, as well as changing machine designs, have resulted in the use of strands with widely varying numbers of wires and a smaller number of available constructions. Typical 637 Class constructions include 633 for diameters under 12, 636 Warrington Seale (the most common 637 Class construction) offered in diameters 12 through 1-58, and 649 Filler Wire Seale over 1-34 diameter.