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 TB 55-1900-232-10
the categories of towing adapters and jewelry. See Figures 2-41 through 2-43
b Synthetic Couplings and Thimbles. For years the standard end fitting for manila hawsers was a rope thimble through
which a shackle was passed. However, with the advent of high-stretch synthetics, the eye of the line could stretch
sufficiently to allow the thimble to tumble out of the eye. In addition, the higher strength of the synthetic lines caused
thimbles to crush and fail. To resolve these problems, several special thimble connectors were developed. Figure 2-41
shows the approved Navy Standard thimble
c. Shackles.
CAUTION
Special forged shackles, when used with chain stoppers and carpenter stoppers, utilize carefully-machined
screw pins and are permissible in towing. Such pins must remain accessible for inspection and service while in
use.
A means of connecting the various components of the towing hawser is provided by use of jewelry such as safety
shackles, plate shackles and detachable links. Components of different sizes are connected by use of offset plate
shackles and pear-shaped detachable links, as shown in Figures 2-41 through 2-43
d Poured Socket.
CAUTION
Whenever a poured socket is installed on a wire rope, the condition of the lubricant in the portion of the rope
near the socket should be checked and new lubricant applied to dry areas.
A poured socket is a wire rope fitting used for terminating the end of a rope. These sockets are also called Spelter
sockets. Sockets are of two types, open and closed. The open socket is fitted with a locking bolt and nut which, in turn,
is secured with a locking bolt with two jam nuts. Frequently used on towing hawsers, the closed socket forms an eye with
a solid bail. The broomed end of the wire is inserted into the socket and secured in place with the poured zinc. Figure 2-
42 demonstrates use of a safety shackle and three standard pear-shaped detachables for connecting the standard
hawser termination to a wide range of chain sizes.
e Swaged Fittings. It is now common to terminate wire rope having wire cores with fittings using the swaging process.
CAUTION
Swaging is acceptable only on IWRC (Independent Wire Rope Core) wire rope. It is not to be used on fiber core
rope.
The wire rope swaging process attaches fittings to wire rope by means of cold plastic flow of metal under extremely high
pressures. The process uses hydraulic presses in conjunction with suitable dies. The swaged fittings are usually made
of special alloy steels This process has the advantage of low cost and high efficiency
2-52
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