MIL-DTL-24677B
3.4 Construction. The rope shall be double braided construction wherein an inner braid of hollow structure
manufactured in a separate operation shall serve as the core, while a cover (outer braid) is braided over it in a
second operation. The weight of either constituent, the inner braid or the outer braid, shall not be greater than 55
percent of the total weight of the rope. Heat setting by the rope manufacturer of yarns or finished rope shall not be
acceptable. Polyester fibers of different types or grades, or fibers of different manufacturers shall not be mixed
within the core or within the cover. Polyester fibers used in the core may, however, differ in type, grade, or
manufacturing sources from those used in the cover, provided fiber components meet the requirements of 3.3. If
the braking elongation of the fibers used in the core and in the cover are different, the higher elongation fiber shall
be used in the core.
3.4.1 Yarns. Core yarns shall be one size and all cover yarns shall be one size, the producer shall provide type
of yarn that has been designed for cordage and tested for its suitability for this application (see 6.3). In the
manufacture of each braid, one half of the yarns shall have an "S" twist, while the remaining yarns shall have a
"Z" twist. Yarns shall have sufficient twist so that the filaments on the outer surface of the inner and outer braids
are essentially parallel to the axis of the rope. The type of braid, number of strands, yarns per strand, and
multipliers for the respective inner and outer braids shall be as specified in tables I and II.
TABLE I.
Structural requirements for inner braid or core.
Rope size,
Multiplier for
nominal, circumference,
Number
Yarns per strand
determination
(inches)
Type of
of
of pick count
braid
strands
Min
Max
Min
Max
3/4
to
2 - 1/4
Plain
8
2
6
1.3
1.9
3/4
to
2 - 1/4
Twill
12
1
4
2.0
3.2
2 - 1/2
to
7 - 1/2
Plain
8
2
6
1.3
1.9
2 - 1/2
to
7 - 1/2
Twill
12
1
4
2.0
3.2
2 - 1/2
to
7 - 1/2
Twill
16
1
3
3.0
3.8
8
to
16
Twill
12
1
4
2.0
3.2
8
to
16
Twill
16
1
3
3.0
3.8
TABLE II.
Structural requirements for outer braid or cover.
Multiplier for
Rope size
Yarns per
determination of
nominal, circumference
Type of
Number
Strand
pick count
(inches)
Braid
of
strands
Min
Max
Min
Max
3/4 to 1 - 1/2
Twill
16
2
3
6.0
7.0
1 - 1/2 to 2 - 1/4
Twill
20
2
2
6.8
7.8
2 - 1/4 to 5 - 1/2
Twill
24
2
2
7.6
8.6
5 to 16
Twill
32
1
2
9.0
11.0
3.4.2 Multipliers. Multipliers shown in tables I and II overcome the complexity of listing a range of pick
counts for every size. Pick count and circumference for either the inner or outer braid shall be measured at the
appropriate load P (table III) for the nominal rope size and shall be used in all calculations for the inner and outer
braids as appropriate. The calculation is as follows:
Multiplier - pick count times circumference.
3.4.3 Texture. The texture of the finished rope shall be firm without sleaziness, and the cover (outer braid)
shall fit closely around the core (inner braid) when inspected with the rope in a relaxed state.
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