switch is engaged, and lights the battery-position
indicator light at deck edge.
Purchase cable
The purchase cable is the wire rope reeved onto the
arresting engine sheaves and fed through fairlead
tubing and over the fairlead sheave to the deck gear on
the flight deck. The purchase cable transmits the force
of the landing aircraft from the deck gear to the
arresting engine.
The polyester-core purchase cable is 1 7/16-inch
diameter, 6 × 31 die-formed polyester-core construc-
tion with no filler wires, all wires are considered
loading bearing, with a minimum breaking strength of
215,000 pounds. The die-formed construction is such
that the outer wires present a relatively flat surface,
giving it the appearance of being worn even when new.
As a result Q reading, as performed on the sisal-core
purchase cable, are not possible. Inspection and
replacement will be based on broken wire criteria.
The sisal-core purchase cable is 1 7/16-inch
diameter, 6 × 25 filler wire construction, right-hand lay,
lang lay cables with a minimum breaking strength of
195,000 pounds. The 6 × 25 filler wire construction
means that the cable is made up of 6 strands with 19
major wires and 6 filler wires per strand. (See fig. 3-25.)
The filler wires provide shape and stability to the
strand. Lang lay denotes cables in which the wires of
the strand and the strand are twisted in the same
direction so that the outer wires in the lang lay cables
run diagonally across the longitudinal axis of the
cables.
The purchase cable is made from high-strength,
uncoated plow steel. A hemp center, made from
resilient oil-impregnated hemp, serves as a foundation
for the strands, keeps the strands evenly spaced, and
prevents them from bearing against each other. The
hemp center also aids in lubrication of the inner wires.
Within the hemp center is buried a paper or plastic strip
bearing the name of the manufacturer. New purchase
cables are provided on a double reel with each reel
containing 1100 feet of cable. The purchase cable used
on a barricade engine is of the same wire rope
construction but is provided as a single cable, 2100 feet
in length with a poured terminal on one end.
Poured threaded terminals are fitted on each end of
the purchase cables. A clevis socket is screwed onto the
threaded terminals to connect the purchase cables to the
crossdeck pendants one end, the other end is connected
to a coupling on the cable anchor damper operating
piston rod (fig. 3-26.)
3-27
MANUFACTURER’S
IDENTIFICATION TAPE
6 STRANDS
PER CABLE
25 WIRES PER STRAND
(19 MAJOR WIRES)
6 FILLER WIRES
CORE
(HEMP, FIBER)
INTERFACE
5
4
3
2
1
6
ABEf0325
Figure 3-25.—Cross section of preformed sisal core purchase
cable.
ANCHOR SCREW
LOCK RING
CLEVIS PIN
CLEVIS SOCKET
CDP SWAGED TERMINAL
CLEVIS PIN
CLEVIS
SOCKET
ANCHOR
SCREW
ANCHOR NUT
ANCHOR DAMPER
COUPLING
ANCHOR NUT
ABEf0326
Figure 3-26.—Purchase cable attachments.
