Wire Ropes, Elements and Definitions - Wire Ropes: Tension, Endurance, Reliability - page 43

Specific minimum breaking force of wire ropes F min /d 2 in N/mm 2

Table 1.10

Rope Rope class Wire rope with fibre core Wire rope with steel core

1,570
(N/mm 2 )

1,770
(N/mm 2 )

1,960
(N/mm 2 )

1,570
(N/mm 2 )

1,770
(N/mm 2 )

1,960
(N/mm 2 )

Single-layer rope 7 9 7 609 687 760

6 9 7 521 588 651

8 9 7 457 515 570 564 635 704

6 9 19 518 584 647 559 630 698

8 9 19 460 519 574 559 630 698

6 9 36 518 584 647 559 630 698

8 9 36 460 519 574 559 630 698

6 9 35 N 498 561 621 542 611 676

6 9 19 M 482 543 602 521 588 651

6 9 37 M 463 522 578 501 565 625

Multi-strand rope 18 9 7 515 581 643 515 581 643

34 9 7 499 563 623 499 563 623

Rope class 6 9 19 = 6-strand Seale, Warrington or Filler
Rope class 8 9 19 = 8-strand Seale, Warrington or Filler
Rope class 6 or 8 9 36 = 6 or 8-strand Warrington-Seale
N for compound lay strands
M for cross-lay strands

Rope breaking forces. F min is the minimum breaking force of the rope in kN. It is
normally obtained by calculation from the product of the square of the nominal
diameter d in mm, the rope grade R 0 in N/mm 2

and the breaking force factor K

F min ¼ d 2

R 0 K
1000

: ð 1 : 6 Þ

In this R 0 is the rope grade in N/mm 2 , i.e. the nominal tensile strength of the wires.
K is the minimum breaking force factor, the empirical factor used in the deter-
mination of the minimum breaking force and obtained from the product of fill
factor f, the spinning loss factor k and the factor p/4

K ¼ p f k
4

¼ k C : ð 1 : 6a Þ

F m is the measured breaking force. This breaking force is obtained by using a
prescribed measuring method.
The measured breaking force F m should not be allowed to fall below the
minimum breaking force F min

F m F min :