FORMING AND LAYING OF ROPES AND CABLES--ROPEWALK METHOD
Before taking up the strictly modern machines so largely used now in
the final processes of rope-making--the forming of strands, laying of
common ropes and closing of cable-laid goods--we shall describe the
ropewalk method of performing these operations as it is practised today.
For making tarred goods in all but the smaller sizes the walk has
certain advantages not afforded by more advanced methods. It also
provides efficient equipment for turning out the largest ropes, which
would otherwise require special machinery.
The long alleys or grounds where the work takes place are usually laid
out in pairs, one for forming, the other for laying and closing. Each
ground has a track to accommodate the machines and an endless band-rope
which conveys the power.
At the head of the forming ground stand frames holding the bobbins of
yarn. The yarns for each strand first pass through a plate perforated
in concentric circles. This arrangement gives each yarn the correct
angle of delivery into a tube where the whole mass gets a certain
amount of compression.
[Illustration: CORDAGE MANUFACTURE BY THE ROPEWALK METHOD
YARNS PASSING FROM BOBBINS THROUGH PERFORATED PLATES
“TOP TRUCK”--LAYING PROCESS FORMING MACHINE--MAKING STRAND
CLOSING TARRED RUSSIAN HEMP CABLE 15¾″ CIRCUMFERENCE FOR ARGENTINE
BATTLESHIP “RIVADAVIA”]
The forming machine--a heavy carriage surmounted by the band-rope wheel
into which are geared several spindles and a driving drum--is now drawn
up, and each group of yarns is attached to a separate spindle as shown
opposite. A rope made fast at either end of the walk is given a few
turns around the drum, the band-rope is set in motion and the machine
moves off, leaving in its wake the compactly twisted strands.
In the case of a common right-laid rope, the forming twist is left
hand. A change to right hand can be made simply by shifting clutches.
The amount of turn or twist depends on the diameter of the drum, which
is adjustable.
Behind the machine follows a man who swings out the stakes, placed
at intervals along the walk, and throws the strands over them. When
the process is completed the strands are cut away at either end and
transferred to the laying ground, the stakes being pushed back to allow
the return of the forming machine for another trip.
[Illustration: INTERIOR OF ROPEWALK, PLYMOUTH CORDAGE COMPANY]
The two laying machines stationed at opposite ends of the walk greatly
resemble the forming machine. One--usually the “afterturn,” so
called--is made fast; the other, or “foreturn,” is braked down but not
secured. The strands are attached to separate spindles on each machine
and given a little extra twisting from both ends--left hand as in the
forming. During this process of putting in the “hard,” so called, as
well as in the laying itself, the foreturn machine is drawn slowly
ahead by the shortening of the strands.
For the laying, the ends of the strands at the afterturn machine
are transferred to a single spindle. The “top”--a cone-shaped
block containing a groove for each strand and mounted on a light
truck--is backed up to the machine, the strands are inserted and the
twisting recommenced, the direction of the afterturn spindles now
being reversed. The resulting tendency of the strands to untwist
is counteracted, partly by a left-hand revolution of the foreturn
spindles, and partly by the presence of the “hard” or surplus twist
just described.
As the top truck is forced ahead by the twisting process, the
rope-maker preserves a correct lay in the rope by means of greater or
less leverage on the “tails”--the loose ropes shown in our picture. The
stakes on which the strands rest are removed one by one to allow the
top truck to pass and are then replaced to support the rope until the
laying is finished and the reeling in of the rope begun.
The closing process on cable-laid goods is like the laying except
that the twist is reversed. The work being with three complete
ropes--frequently very large--a heavier top truck is necessary, and
this must often be ballasted, as shown in our illustration on page 80,
to keep down the vibration which would otherwise tend to lift the truck
off the track.
[Illustration: SIXTEEN-INCH TOWLINE WITH EYE-SPLICE]
[Illustration: LATHYARN AND TIE ROPE MACHINES, NO. 2 TAR HOUSE,
PLYMOUTH CORDAGE COMPANY]
[Illustration]