IMPROVEMENTS IN THE INSULATED COATINGS AND COVERS OR CASES FOR WIRES AND CABLES FOR TELEGRAPHIC AND OTHER ANALOGOUS PURPOSES, AND IN MACHINERY OR APPARATUS EMPLOYED IN APPLYING THE COATINGS TO THE SAID WIRES OR CABLES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Thomas Jefferson Mayall at the
Office of the Commissioners of Patents on the 21st July 1881.
THOMAS JEFFERSON MAYALL, of Reading, in the County of Middlesex, and
State of Massachusetts, one of the United States of America. "IMPROVEMENTS
IN THE INSULATED COATINGS AND COVERS OR CASES FOR WIRES AND CABLES
FOR TELEGRAPHIC AND OTHER ANALOGOUS PURPOSES, AND IN MACHINERY OR
APPARATUS EMPLOYED IN APPLYING THE COATINGS TO THE SAID WIRES OR
CABLES."
The first part of my Invention relates to the insulation of the wires, and to
external covers or cases for protecting the same, either under or above the surface
of the ground or in water, and it consists in enclosing a gang of wires within a
strap, belt, or rope of rubber, gutta-percha, or other similar plastic insulating
substance. One or more of such straps or ropes are then enclosed in an external
case or cover extending, by preference, the whole length of the line, the external
case or cover being formed of sufficient size to receive as many straps or ropes
containing gangs of wires as may be required for the use of the line.
:
In carrying out my Invention I prefer to employ copper wires on account of.
their lightness and great conducting power. Wires formed of other metals may
however be employed.
The strap or belt in which a gang of wires is enclosed may be about three (3)
inches wide by about three eighths (3/6) of an inch in thickness, and in lengths
most convenient for transportation and handling.
I prefer to make them of a compound of india rubber and graphite in the.
proportion of about two and one half (2/2) pounds of graphite to one (1) pound of
rubber by weight with enough sulphur to insure proper vulcanization.
This compound I bring into a plastic state by grinding or other suitable means.
The rubber compound is then run into sheets of the proper thickness, say, three
sixteenths () of an inch, and then cut into strips of the desired width, say,
three (3) inches.
These strips are then cemented together end to end to produce strips of the;
desired length.

page_text: A gang of, by preference, ten (10) wires are used in a strap or belt of the width
of three (3) inches.
By any suitable means the wires are laid perfectly straight, parallel with each
other and at equal distances apart, and enclosed between two strips of the rubber
compound, after which the strips are submitted to a sufficient pressure by means
of rollers, as hereinafter described, or otherwise to weld tlie two strips of rubber
compound into one homogeneous mass with the gang of wires in the centre.
I then vulcanize the rubber to such a degree as to make it inflexible.
A sufficient number of such pieces to extend the whole length of the line are
joined together as laid by connecting the wires at the ends and filling the spaces
between and around the point of junction with plastic rubber compound, which is
protected by winding a band of rubber around the junction.
I prefer to lay the straps or belts edgewise in the box. A case three inches by
four inches inside would contain ten of the straps or belts, each enclosing a gang
of ten wires, in all one hundred wires.
I make the case to contain the gangs of insulated wire with a cover which can
be easily removed when necessary, and I prefer the rubber and graphite compound
-vulcanized to become rigid as the material to make such cases, as it is a very
perfect insulator.
These cases may be provided with branches whenever it is desirable to have
one or more gangs of the wire diverge from this line into which one or more of the
straps or belts may be carried, or a strap or belt may be divided, and a part of
the wires it contains diverged from the main line.
If a single strap or belt is to be used the case may be dispensed with, and the
strap buried in the ground or fastened to the side or roof of buildings.
In constructing a line of telegraph by this method, it will generally be found
desirable to put the case or cover containing the gangs of insulated wires below the
surface of the ground, deep enough to escape injury from any movement on the
surface; but where the circumstances are such that it is impossible or undesirable
to place the wires in the ground, they may be upon or supported at any desirable
distance above the surface.
In cities and large towns where there are a large number of wires required by
the present system to be supported on poles on the roofs of buildings, this Invention
will be found especially convenient and useful, as by it all the wires may be placed
under the side walks and pavements.
Wires insulated and laid by this method will at all times convey the electric
current with greater certainty and effect than those exposed on poles; but in
stormy weather the advantage will be very great, as the insulation will be perfect
as in fine weather, and there will be no breaking of wires by wind or loading thei
with snow and ice.
It is also especially adapted for use under water in the crossing of rivers and
other waters by telegraph lines, the rubber and graphite combining great strength
and perfect insulation.
In some cases the wires may be enclosed by laying them on one strip of the
rubber and graphite compound, and then rolling it up transversely. In both ways
the compound must be submitted to pressure sufficient to weld it perfectly into a
homogeneous whole, and then vulcanized. Several wires may be coated singly,
and then laid together and pressed into the form of a belt or rope, as may be most
convenient for use.
.. Wires insulated with a coating of the rubber and graphite compound of
considerable thickness, say about one half (/) inch may be laid in the ground
without any other protection, and will remain in a state of perfect insulation for a
great length of time.
In the construction of the external case or cover I use as the best non-conducting
material that I know of a compound of rubber and graphite, thoroughly ground
and mixed with a portion of sulphur to aid in vulcanization.
I mould the cases in two parts, the lower part being usually the receiving part,

page_text: and the upper part the cover made to fit tightly together, and then vulcanize them
in or out of the mould as in practice may be found most desirable.
The rubber and graphite are used in the proportion of one (1) pound of rubber
to about two and one half (2) to four (4) pounds of graphite, and about eight
ounces of sulphur.
These cases or covers are formed and vulcanized in moulds of convenient length,
say, from four to twelve feet generally, and need no finish after vulcanizing, except
to square or otherwise adapt the ends to be joined together.
In laying them in a line of telegraphs, the lower or receiving part is first put
down with a piece of the rubber and graphite compound under each joint; this
being continued for some distance the wire or wires insulated or otherwise are
laid in the cover, the covers are then put on with rubber cement in the joint
between them and the lower or receiving part of the box. The plastic rubber at
the end of the joint is then well covered with cement on the inner side, and
closely wrapped around the joint, the work being well done the box is perfectly
tight, and no moisture or air can enter it except at the open ends. The open
ends may also be tightly closed with plastic rubber and graphite compound
and cement.
If it is desirable to branch off a part of the wires of a line at any given point,
the box may be made with a branch at that point into which any portion of the
wires in the main line may be diverged to reach a station, or to construct a
branch line.
If more than one wire is to be laid in the case here described, each wire must be
insulated by itself from all the other wires laid therein.
My Invention also relates to machinery or apparatus for enclosing a gang of
wires for telegraph or other similar purposes in a strap or band of insulating
compound, the strap or band similar to that herein before described. Any number
of telegraph wires, from two to twenty, or even more if occasion requires, is made
of a compound of rubber and graphite with a portion of sulphur to aid in curing
or vulcanizing the compound thoroughly commingled and blended together in a
plastic mass by grinding or other suitable means.
This compound is run out into sheets of one half the thickness required for the
band when finished with the wires in it.
These sheets are cut into strips of the width required for the band, and the
strips are cemented end to end together to make a length convenient, the strips
are then covered on one side with muslin or other suitable material and wound up
on large spools, the use of the muslin being to prevent the layers of the strip
from sticking together as it is wound up on the spool. A gang of wires are laid
parallel to each other at equal distances apart, and a strip of the rubber and
graphite compound laid on both sides of the wires and pressed together with the
wires between them with just sufficient force to weld the two strips into one
homogeneous band with the wires in the middle of it.
The object of the machine is to form the band of rubber and graphite compound
with the wires in the middle of it laid at equal distances apart and parallel to each
other.
There are lower and upper pressing rollers, also a trimming roller over which
the band of rubber compound passes, and on which it is cut to uniform width by
revolving cutters.
The distance apart of the cutters may be varied as required according to the
width of the band for the time being treated, the edges on the circumference just
touching but not bearing upon the trimming roll, and trimming both edges of the
band as it passes between them when the machine is in operation.
Two pins or standards guide the band as it passes from between the pressure
rolls to the trimming roll for the purpose of keeping the band in its proper
position.
There is a pulley on the shaft of one of the pressure rolls over which a belt
passes to drive the receiving spool.
+

page_text: There is a pair of rolls between which the wires pass, one of which rolls has
circumferential grooves, one for each wire, for the purpose of keeping them in their
proper relative positions.
There is a throat through which the wires and the two strips of rubber compound
pass to the pressure rolls.
A transverse bar is provided with openings through it at equal distances apart
through which the wires pass.
Strips of rubber and graphite unwind from their spools and pass with the wires
through the throat to the pressure rolls.
The strips of muslin which are separated from the strips of rubber by being
drawn away by and wound onto the spools, which spools when full are rewound
and the fabric drawn therefrom for re-use as required.
The receiving spools for taking up the muslin as it is separated from the strips
of rubber are provided with pulleys, rubber faced, which engage with the teeth of
gear and take motion from it by friction. A binding roll is arranged above the
spool which takes up the strip of muslin.
The rubber compound strip and the muslin strip are drawn off spools together.
There is a guide or supporting roll for the lower strip of rubber compound.
A box contains powdered tale or other similar substance through which the band
is made to pass by rolls properly arranged to change the tacky or sticky condition
of the surface of the rubber compound.
Three rolls are arranged to carry the band of rubber compound with its enclosed
wires through the mass of powdered talc.
Revolving brushes running against the two sides of the band remove any
surplus of powdered tale adhering to the band.
Other rolls guide and give tension to a strip of tin foil which is drawn off from
a spool and passing downwards is wound with the band upon a receiving spool,
the purpose of the tin foil being to keep the layers of the band from adhering
together.
There is an arrangement of weights, levers, and fulcrums for the purpose of
pressing the spool up against the roll in order to wind the muslin smoothly on the
spool. A similar arrangement being adopted in connection with the upper spool
which takes up the upper strip of muslin.
A series of spools of wire are mounted on cross bars carried by a standard, and a
bar also carried by the standard and is formed with openings for the passage and
guidance of the wires. There is a clutch for engaging or disengaging.