FORMING AND LAYING OF ROPES AND CABLES--FACTORY METHOD, TWO-MACHINE
SYSTEM
Unlike the ropewalk system of making strands, ropes and cables
described in the preceding chapter, the factory method, so called, is a
development of the last few decades only. From the first this company
has been a leader in purchasing the best stock machines obtainable and
in designing devices to fulfill special requirements--a policy which
has given us unequalled production facilities.
To describe this equipment in detail would require an entire book. We
shall attempt, in this chapter and the next, to give an idea of the
principal machines only.
There are two methods to the modern system: that in which the strands
are formed on one type of machine and twisted into a rope on another;
and that in which both operations are performed on a single machine.
The second method carries with it the advantage of economy in space and
equipment, but is not followed so generally with the larger sizes of
rope as is the first.
A complete set for the two-part method comprises two or more
horizontal strand-forming machines, several bobbin frames and a
vertical laying-machine. In our illustration, the latter is shown
making three ropes into a cable--a process essentially the same as
where three strands are united into a single rope.
Three men usually suffice on the strand-making--one to tend the
machines, the others to tend the bobbins which turn on fixed posts and
can be renewed as needed without interrupting the process.
The yarns are first drawn from the bobbins through the perforated
plates seen in the lower section of the picture, the entire number
being so distributed as to converge in layers and at the proper angles
around one central yarn. They next pass into a tube. Here the whole
mass is compressed and at the same time is twisted by the revolution
of the long carriage or flyer, which, as our picture shows, supports a
winding-reel and two capstans.
The strand can be twisted right or left hand as called for. The amount
of twist is regulated by the flyer’s speed--easily varied by the use of
different gears.
The two capstans are geared to pull the strand through the tube and,
by holding it taut, keep the twist uniform. The reel also has its
separate gears and revolution. Whenever the increasing diameter of the
load tends to make it exert too much strain on the strand, the reel is
slowed down by an ingenious friction device. The strand is guided into
even layers on the reel by an arm which is made to travel from side to
side.
Here, then, are four distinct operations going on at once and all in
perfect harmony. From this may be judged the many difficulties which
had to be overcome before strands could be manufactured in such small
space.
[Illustration: HORIZONTAL FORMING MACHINES MAKING STRANDS
VERTICAL LAYING-MACHINE MAKING OIL-WELL CABLE
FORMING MACHINES (WINDING REEL ON FARTHER MACHINE REMOVED)
ROPE-MAKING MACHINERY, PLYMOUTH CORDAGE COMPANY]
The illustration opposite page 85 shows the machines which make
Plymouth Lathyarn and Hide Rope. Although somewhat smaller than the
type just described, these machines are constructed and operate in
practically the same manner. The speed of their flyers is naturally
much slower, however, since the goods they work on need not be twisted
so hard as a rope strand.
For the laying process, in which the strands are united to make a
rope, the full reels are removed from the forming machines by overhead
chains, as shown on the opposite page, and by like means are placed in
the vertical flyers of the laying-machine. The strands pass through
openings in the top-piece just above the flyers and converge into a
central tube still higher up to form the rope.
[Illustration: REMOVING REEL WITH STRAND FROM FORMING MACHINE]
When the machine is in operation the whole lower portion, from the tube
down, revolves, either to the right or left as the goods require, and
thus puts the twist into the rope. This twist being opposite, always,
to that of the strands, the natural tendency of the latter as they are
laid together would be to loosen up. To regulate this, each flyer is
made to revolve on its own axis--in a direction opposite to the general
direction of the machine. Each reel revolves also on its axis to feed
out the strand--the effect of the changing load being met as before by
a friction attachment.
The overhead pulleys, which perform the same mission for the rope that
the capstans previously did for the strands, deliver the finished
product onto a belt-driven coiling reel where it is guided into even
layers by the workman tending the machine.
As already explained, the laying-machine is used in the same way when
three ropes are made into a cable. When a four-strand rope is to be
turned out the machine has four strand-reels. If the strands are
to be laid around a heart rope, as in transmission goods, the heart
feeds directly into the twist tube from a smaller reel placed on the
top-piece previously mentioned.
All the foregoing machines are equipped with ingenious devices for
measuring the strand or rope as it is made, so that the attendant
can tell instantly from the gauge how many feet have been run. The
features we have here touched on are only a few of the many that
have transformed the final stages of rope-making from a laborious
task--dependent for its success on the skill of the individual
expert--into quick, sure operations where every problem is met with the
unfailing accuracy of a perfect machine. Rope nowadays is, generally
speaking, made more scientifically, more uniformly than it was in the
days of strictly hand processes. And the end is not yet. Better and
still better rope should mark the years to come.
[Illustration: FOUR-STRAND COMPOUND LAYING-MACHINE]
[Illustration]