ROPES AND ROPE MAKING; YARN NUMBERING
A considerable quantity of the smaller-sized ropes are now made on what
are termed “house machines.” These machines perform the same function as
those in the rope-walk but they occupy a much smaller space; they are
adapted to deal with a great range of sizes although, in general, it is
not necessary to use one machine for a large range of work; there is
such a variety of ropes in use that in a well-equipped rope works it is
possible to keep each machine almost constantly on ropes within a small
range of size. These remarks refer, as indicated, to ropes which come
within the limit of, say 2 to 3 in. in circumference. In the manufacture
of the larger sizes of ropes, it is usual to use two distinct machines,
one termed the “strander,” and the other the “closer,” and, although the
house-machine made ropes are often considered inferior to those made in
the rope-walk, many of the objections urged against the untarred ropes
made in the house-machine are more imaginary than real.
Fig. 29 is illustrative of a number of machines of a type used for the
making of ropes in which twelve to forty-five threads may be combined in
one operation during the manufacture of a three-strand or a four-strand
rope. The bobbins are placed in creel flyers of which there may be three
or four according as the rope is to be a three-strand or a four-strand
one. The creel flyers are composed of two parts, one of which carries
the bobbins, and the other carries the hauling and twisting gear. All
the three or the four strands are made at the same time; when formed,
they leave their respective flyers and converge towards the top and the
die or central tube where they are formed into a rope by the proper
degree of twist according to the purpose for which the rope is to be
used. Finally, the finished rope is drawn forward by a series of hauling
pulleys which also conduct the rope to the winding-on reel or bobbin,
and by suitable mechanism the rope is wound into a temporary form of
coil. As the bobbins are filled with rope they are removed from the
machine and conveyed to special coiling machines where they are measured
when necessary as they are made up into coils suitable for the
particular purposes desired. A common length of coil is 120 fathoms.
[Illustration: _By permission of the Edinburgh Roperie Co._
FIG. 29
ROPE-MAKING (HOUSE MACHINES)]
Although the various house machines represent the latest developments in
the art of stranding and closing--the two essential operations of rope
making--a modern rope and cordage works is provided not only with the
various machines which have been illustrated and described, but also
with a well-equipped rope-walk so that the products may include a great
variety of cordage from the finest lines to the mammoth ropes for ships,
steamers, harbours and heavy hauling purposes generally.
The combination of the house machines and the modern rope-walk makes
present arrangements very complete when compared with the old type of
rope-walk, but the apparatus employed in these old rope-walk machines
embodies all the principles of construction which are present in the new
machines for the same class of work.
Rope-walks are, naturally, long, narrow buildings because the full
length of the rope is in one stretch.
The work which is conducted in such places and the type of building is
admirably portrayed in the first three verses of Longfellow’s poem--
THE ROPE-WALK.
In that building long and low,
With its windows all a row,
Like the port-holes of a hulk,
Human spiders spin and spin,
Backward down their threads so thin,
Dropping, each, a hempen bulk.
At the end an open door;
Squares of sunshine on the floor
Light the long and dusky lane;
And the whirling of the wheel,
Dull and drowsy, makes me feel
All its spokes are in my brain.
As the spinners to the end
Downward go and re-ascend,
Gleam the long threads in the sun;
While within this brain of mine
Cobwebs brighter and more fine
By the busy wheel are spun.
At the top of the rope-walk is a stand or bank which contains the
bobbins of yarn, and this yarn may be dry or tarred according to
requirements. The bobbins are arranged on pins and the necessary number
of yarns for each strand are drawn from the bobbins and passed, in their
proper order for ensuring a uniform strand, through a number of holes in
a “register plate” immediately behind the machine. In a modern machine
any number of strands up to six can be formed at the same time, and
hence there will be six register plates for the yarns. For the
larger-sized ropes only one strand can be drawn out in one operation.
A machine termed a “traveller,” is employed to draw out the strands, and
this machine is provided with a series of hooks as well as a central
spindle. The strands may be attached as required either to the hooks or
to the spindle. A rope-driving gear causes this traveller to move on
rails down the walk and for the distance required, and it will be
evident that as the traveller recedes from the bank it will draw the
groups of threads from the bobbins and through the register plates; at
the same time the several hooks are caused to rotate, and thus each
strand is twisted and hauled simultaneously.
When the traveller has moved backwards or downwards for the necessary
distance to form the length of strand, the strands are removed from the
hooks and attached to suitable supports until a sufficient number has
been made for closing or laying-up.
To form the strands into a rope, it is essential to use a fixed or
stationary machine along with the traveller and a top-cart. The
stationary machine is substantially built, and, _inter alia_, is
provided with a central spindle around which are grouped a set of
hooks--usually in sections of two circles. Two wheels on the central
spindle drive a number of pinions, one behind each hook, the ratio of
one wheel to half the pinions is 34 to 16, while the ratio of the other
wheel to the other half of the pinions is 54 to 11. Thus, the
revolutions may be--
1 to 1 when the strand is on the central spindle,
34 to 16 or approx. 2 to 1 when on large hooks, and
54 to 11 „ „ 5 to 1 when on small hooks.
When the necessary strands to form the rope are stretched between the
stationary machine and the traveller, an extra amount of twist is
imparted to each strand, an operation which is termed “hardening the
strand”; the amount of twist can be judged only by past experience,
although it is common to give instructions in the words “harden so many
fathoms”; at other times the strands are hardened until the threads form
a desired angle. In all cases the strands should be twisted equally so
that the same tensile stress is on each strand. After this twist has
been applied, all the strands are placed either on one of the hooks or
on the central spindle of the traveller. A top-shaped block is put into
position inside the three strands--this top is in full view in Fig. 30,
which, by the way, illustrates the laying of a 28-in. circumference
four-strand hawser with a central core--and the machines started for a
few revolutions. When the first make of the rope is formed, the top is
brought back to its proper place, a few pieces of rope, termed tails,
are placed round the newly-formed portion of the rope, and these may be
collected and held in position by a bar as shown; one of these tails was
removed when the photograph was taken in order to show the finished part
of the rope between the top-cart and the traveller. The traveller is now
braked to keep the rope taut while the rope-maker lays the strands, the
hooks of the stationary machine at the top of the walk as well as the
hooks on the traveller being rotated meanwhile at a speed which is
suitable for the make or lay of the rope. The hooks in the two machines
rotate relatively about 7 to 9 or 7 to 11.
[Illustration: FIG. 30
LAYING OF A FOUR-STRAND CABLE-LAID ROPE IN THE ROPE-WALK]
When a hawser or cable-laid rope or a “trawl warp” is desired, the
formed ropes are again placed in position, and the whole routine
repeated, while if the warp is to consist of more than three strands, a
heart must be inserted, as exemplified in Fig. 30, upon which to lay or
build the strands. It will be understood that the view in Fig. 30 is the
interior of “a rope-walk,” and that the operative is looking towards the
top of the walk where the stationary machine is situated.
After the laying is completed, the finished rope must be made into a
coil ready for transportation. The coiling machines are often in close
proximity to the house machine or the rope-walk, and for the coiling of
such ropes as that illustrated in Fig. 30, it is obvious that the
machine must be of substantial build. When such a large rope is complete
and ready for despatch, it resembles the 18-in. circumference mooring
rope in Fig. 31; this rope was 90 fathoms long and two tons weight, and
was coiled in about ten minutes by a machine specially designed for the
purpose.
[Illustration: FIG. 31
VIEWS OF LARGE AND MEDIUM-SIZED COILS OF ROPE]
Rope driving has practically revolutionized the construction of modern
mills since ropes are used not only as a direct drive from the rope
pulley on the engine or motor shaft, but at many intermediate places,
and have replaced many installations of wheel-gearing. These
mill-driving ropes, which are invariably from 1½ to 2 in. in diameter,
are made extensively of cotton, hemp or manila. In exceptional cases
more than forty such ropes are used on the same pulley. The frontispiece
illustrates a rope drive in which seven ropes each of 1¾ in. diameter,
are utilized on the shaft of a motor for conveying the motion to a mill
shaft seen in the distance. Other ropes are seen in the next rope alley.
Somewhat similar ropes, but of a smaller diameter, are used for hauling
in the baling press illustrated in Fig. 15.
There are several methods of numbering yarns, most of which involve a
direct relation between the weight and length. Thus, to quote six of the
most widely-practised methods in the textile industry we have
Silk: count no. = the no. of hanks of 840 yards each in 1 lb.
Cotton: „ = „ hanks „ 840 „ „ „ 1 „
Wool: „ = „ skeins „ 256 „ „ „ 1 „
Worsted: „ = „ hanks „ 560 „ „ „ 1 „
Linen: „ = „ leas „ 300 „ „ „ 1 „
Jute: „ = the weight in lbs. of 14,400 yards
Hemp is sometimes reckoned according to the linen system and sometimes
by the jute system.
An entirely different method of counting or numbering obtains in regard
to ropes. The system of yarn numbering for ropes depends upon the number
of single yarns or threads required to make one strand of a 3-in.
3-strand rope. Thus, if 25 yarns are required to form such a strand, the
yarn is 25’s, while if 30 yarns were required for the same thickness of
strand, the yarn would be 30’s, and so on. The tube through which the
yarns are drawn is nearly half an inch bore.
If the yarn number is multiplied by 5, the product represents the number
of yards of yarn in 1 lb. Thus, in the above 25’s yarn there are
25’s × 5 = 125 yd., or 375 ft. per lb.
Ropes are usually designated by their circumferences in inches, and also
by the number of strands neglecting the heart if such is required.