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Aug» 3, 1948.
Filed June 8, 194,5-
Patented Aug. 3, 1948
Edmond s. McConnell, Scarborough, N. Y., and
Wlnfred K. Prlestley, West Barrington, and
Victor F. Volk, Bristol, 8.11., assignors to United
States Rubber Company, New York, N. Y., a
corporation of New Jersey
Application June 8,1945, SerialV No. 598,310
z Claims. (Cx. 114-120)
This invention relates to an insulated electrical
conductor that is so constructed that it has an
exceptionally small over-all diameter and light
Vweight for its service conditions.
The present insulated electrical conductor may
be used in many kinds of services but because of
its light weight, small size and resistance to fire,
solvents and the deteriorating effects of fungus,
it is particularly well adapted for use in the wir
ing of aircraft.
One object of the present invention is to pro
However, fibre glass is very difficult to convert
into a moisture resisting layer or covering and
furthermore it has been found extremely suscep
tible to mechanical abrasion. In applying fibre
glass next to the metallic conductor and subse
quently covering it with an insulating and mois
ture resisting elastic jacket as herein disclosed
it is no longer necessary to impregnate or mois
ture proof the insulating layer of fibre glass.
Furthermore, by covering the metallic conductor
with the fibers parallel as obtained by wrapping
and serving. it is found that cutting and breaking
of the glass and fibres is much diminished as
vide- an insulated conductor that is highly re
sistant to an external flame and to internal heat
compared with a braid wherein the fibres of glass
from' an over-loaded conductor.
Another object is to provide an insulated con 15 cross over and under each other.
The insulated electrical conductor of the pres
ductor, that is lighter in weight and smaller in
ent invention may have a solid or stranded con
over-all diameter than the insulated conductors
ductor, around which is placed one or more layers
'available heretofore for use in wiring aircraft.
of fire and fungi resistant non-adhering mate
Another object is to provide an insulated conductor which will render satisfactory service un 20 rial, such as a serving or wrapping, a tape, or a
braid formed of non-combustible fibers such as
der an extremely wide range of high and low tem
fiber glass or asbestos. This serving is laid di
peratures and is capable of withstanding repeated
rectly upon the metal conductor and can be slid
cycles of high heat and extreme cold.
appreciably thereon to expose a short end portion
Another object is to provide an insulated con
ductor which is highly resistant to fungi, by 25 of the conductor when desired.
Over the fiber glass or other non-combustible
selecting materials which are immune to fungi,
layer is provided an insulating material forming
or by completely enclosing any material subject to
an elastic jacket that has good resistance to mois
such attack with other resistant covering mate
ture. The insulating jacket is preferably formed
Another object is to provide an insulated con 30 of polychloroprene latex (neoprene latex) which
has good flame and fungi resistant properties,
ductor which is highly resistant to the deterio
but may be formed of natural rubber or other
rating influence of solvents such as gasoline,
rubber or rubber-like materials including the
lubricating oil, ethylene glycol, fluids used in
vinyl derivatives that are compounded to give
hydraulic systems, and fresh and salt water.
them elastic properties.
Another object is to provide an insulated con
However since the fiber glass layer is likely
ductor that is highly fiexible and has a tough
to have minute fibers extending radially from
smooth finish which together with its small diam
the surface thereof, it is desirable to cause these
eter facilitates its installation.
. minute fibers to be held down before the plastic
Another object is to provide an insulated con
ductor which is so constructed that the insula 40 jacket is applied, in order to secure a maximum
degree of dielectric strength from a minimum wall
tion can be easily and quickly pushed back ad
thickness of the plastic jacket. This may be done
jacent an end of the metal conductor to expose a
by applying a thin film of varnish or lacquer over
short end portion of the bare conductor, without
the fiber glass before or after it is applied as a
damaging or nicking the conductor. This per
layer. Better results however are obtained by
mits an end of the conductor to be quickly ex
wrapping a layer of textile fibers such as cotton,
posed so that it can be soldered or otherwise at
rayon or nylon over the fiber glass layer, or by
tached to a terminal.
winding a thin tape of flexible plastic material
Another object is to provide an insulated con
such as Cellophane over the fiber glass.
ductor having a light color and smooth finish
The elastic jacket when formed of neoprene
that will remain clean and thus facilitate identi 60
fication of circuit markings printed or stenciled
Another object is to provide an insulated elec
trical conductor that makes more effective use of
the dielectric properties of fibre glass.
latex is preferably applied by the liquid-dipped
method to insure that the coating will be dis
on the surface.
fore nbre glass has been used as an outer braid
or covering because of its fire resisting qualities.
posed concentric to the metal conductor. A good
practical form of apparatus for applying this latex
55 jacket is disclosed in the Bartlett Patent No.
2,353,987 for Liquid applicator. However, the
insulating jacket may be applied by extrusion,
taping or other' processes which are known in
conductor with a harder and smoother outer
underlying serving to any appreciable extent but
will be bonded fIr-mly thereto.
It is desirable to provide the insulated elec
trical conductor of the present invention with a
surface than is provided by neoprene. This is
accomplished by placing over the neoprene jacket
a '.thin tough coating of varnish, lacquer, or
smoother and harder outer surface than is pro
vided by neoprene. Therefore in accordance
with the present invention the neoprene jacket
resinous material such as nylon or vinylite. This
thin tough coating may be applied by a. liquid
dlp process or by extrusion or taping.
' The above and other objects of the present
I3 has deposited thereover a thin illm Il of a
synthetic linear polyamide such as nylon. The
nylon used for this purpose is preferably an alco
the insulated wire industry.
It is desirable to provide the present insulated
hol soluble nylon such for example as is sold on
the market under the designation of type 6B and
which is made as defined by claim 8 of the patent
to Brubaker et al., No. 2,285,009. This nylon
solution is preferably applied over the neoprene
jacket by employing the apparatus disclosed in
invention will be further understood from the
-'i'ollowing description when read in connection
with the accompanying drawing illustrating one
good practical embodiment of the invention.
Fig. 1 is a side elevation of an insulated elec
trical conductor constructed in accordance with
the above cited Bartlett patent, as it is found
that this causes the nylon illm to embrace the
the present invention and showing each insulat~
neoprene jacket tightly. The nylon which has
ing layer partly removed; and
20 high tensile strength appears to shrink about
Fig. 2 is an enlarged transverse sectional view
the jacket to hug it tightly. The alcohol used
taken on the line 2-2 of Fig. l.
as a solvent for the nylon does not produce any
The conductor it may be formed of a single
harmful swelling of the neoprene. The nylon
wire but is -preferably formed of a number of
however may be otherwise applied. It may be
strands of annealed copper and these strands are 25 desirable to add a white pigment or coloring
preferably tinned, as this will give a protruding
matter to the nylon solution so as to give the
bare end portion of the wire added protection
` finished insulated electric conductor any desired
and facilitate soldered connections. About the
color which will facilitate identification of the
conductor i0 is wound a serving il of non-com
same when installed. A white or light colored
bustible material. This serving is preferably 30 outer surface for the conductor affords the fur
-fformed of a number of parallel illaments or
ther advantage in that identification numbers
strands of ll-bre glass and is wound tightly
printed or vstenciled thereupon will show up
around the conductor [email protected] but is not adhesively
secured thereto, so that the serving may be slid
¿is further disclosing the present invention.
the following dimensions are given of one good
back a short distance from an end of the wire
[email protected] when it is desired to expose a short end por»
practical construction that is now being manu
tion of the wire so that it can be secured to a
factured for installation in aircrafts and which
contact member.
has an AN conductor size it, this being very
As above stated ñne glass ?lbres are likely to
nearly the same as A. W. G. size it.
protrude from the surface of the nbre glass
layer il and if it is attempted to deposit an inE
@ver-all diameter
sulating material such as neoprene as a jaclret
Stranded conductor l0 _______________ __ .050”
dlre'ctly over the layer il, these protruding fibres
will extend into such jacket and reduce its di
Cotton layer i2 ______________________ __ .,illiil'l
electric strength.
'l‘his dimculty may be over
Fiber glass layer ll __________________ __ .055"
45 Neoprene latex Jacket lll ______________ __ .089"
come by applying a film of varnish or shellac
Nylon nlm léi ________________________ __ .093"
over the layer il or to the liber glass before or
Insulated electrical conductors of the present
after it is wound upon the conductor, but this
invention having these dimensions have met
makes it more diillcult to slip the layer li by a
satisfactorily aircraft service conditions.
sliding movement back from an end of the oon 50
lt is stated above that the present insulated
ductor it. Therefore a serving of cotton, rayon,
electrical conductor is smaller in size and lighter
nylon or other iibrous material is preferably
in weight than other commercial insulated elec
wound over the layer il in the opposite direc=
tric conductors now on the market and having the
tion as shown in the drawing to form the second
same cross-sectional area of conductor. The fol
insulating layer i2. However this second layer 55 lowing table is given as showing a comparison
. may be wound in the same direction as the first
between several conductors of the present con
layer. The cotton or rayon may be treated with
struction and that of representative commercial
a fungi resistant material before or after it is
constructions now on the market andihaving a
applied to increase the protection of the electric
corresponding metallic conductor.
conductor from fungi. This second layer i2 holds @il
down and covers the protruding ñbr‘es of the
Prior Commercial
Present Construction
layer il and provides a satisfactory surface to
receive a jacket i3 of insulating rubber or other '
elastic material. The jacket i3 may be formed
of various types of natural or synthetic rubber d5
Size l
Weight lbs.
1000 it.
Weight lbs.
and of elastic vinyl derivatives, but preferably
is formed of neoprene latex; thatfis polychloro
prene latex because of its good resistance to
moisture, solvents and combustion or burning,
and the neoprene latex is preferably applied by
`the liquid-dipped method above mentioned so as
_to make sure that this jacket will be of uniform
_thickness around the conductor. .The neoprene
when applied in this manner will not enter the 75
1 AN (Army~Na
Conductor size which is ve ry near] y the sem o
aan. W. G. size. Vy)
This table shows that the present construction
is considerably smaller in diameter and lighter
in weight than a representative prior construc
tion that meets the same service conditions.
By employing a ilber glass layer II that is
wound next to the conductor Il but is not adhe
sively secured thereto a lighter and more ilexible
construction is secured than when the liber glass
layer is impregnated with a bonding material.
Furthermoreif all the other layers I 2, I2 and Il
are destroyed by ñre the fiber glass layer II may
still serve to insulate the conductor Il.
'I'he fibrous cover Il, as above stated, prevents
ilbers from the cover II from entering the Jacket
therewith but not bonded thereto, a serving of
fibrous textile material wound over the libre glass
so as to hold down stray glass libres, an elastic
jacket formed of a homogeneous plastic having
lgood resistance to iiame and moisture covering
said textile serving, and a thin strong film of
synthetic linear polyamide covering and snugly
embracing said elastic jacket and having an out
side diameter that is less than twice the diameter
of the bare metal conductor, whereby a~ well
covered highly flexible conductor of excellent in
sulating properties is provided and the insulation
adjacent an end can be readily slid back to expose
a short portion of the conductor.
I3. It also increases the insulating properties of Il 2. An insulated electrical conductor having ex
the covering materials, and it is protected from , cellent abrasion, flame and moisture resisting
moisture by the jacket I3;
properties, comprising a metal conductor, a rib
The jacket I3 when formed of neoprene latex
bon-like serving of nbre glass wound in short
will have excellent llame and moisture resisting
spirals about the conductor in direct contact
properties and will be highly resistant to the de
therewith but not bonded thereto, a serving of
teriorating influences of solvents such as gasoline.
lubricating oil, ethylene glycol, ñuids used in
hydraulic systems, fresh water and salt water,
all of which may be present at diilerent times to Y»
conductor wires installed in an airplane. Fur
thermore neoprene is well adapted to withstand
cold temperatures.
The nylon illm Il has high tensile strength and
provides the conductor with a tough, smooth
outer surface of light color, so that the wire iden
tiilcation numbers placed thereupon will show up
clearly and will not be readily obscured by grease
or dirt.
All of the covers II, I2, I2 and Il are so formed
fibrous textile material wound over the ñbre glass
so as to hold down stray glass fibres, a, jacket oi
poly-chloroprene bonded to the textile serving,
and a thin strong film of synthetic linear poly
amide covering and snugly embracing said jacket
and having an outside diameter that is less than
twice the diameter of the bare metal conductor,
whereby a well covered highly nexible conductor
o1' excellent insulating properties is provided and
the insulation adjacent an end can be readily
slid back to expose a short portion of the con
and applied that they aiiord the conductor Il
excellent protection and insulation for the total
thickness of the insulating material, and produce
a highly ñexible insulated conductor.
The in- A
sulating material is suiiiciently comprensible as
' The following references are of record in the
a whole to be readily pushed back from an end
of the conductor Il to expose a short end portion
so that it can be secured to a tenninal. This
makes the use of a mechanical stripping tool
which is likely to nick or otherwise injure the
conductor I0 unnecessary.
Having thus described our invention, what we
claim and desire to protect by Letters Patent is:
l. An insulated electrical conductor having ex
cellent abrasion, llame and moisture resisting
properties, comprising a metal conductor, a rib
bon-like serving of n_ber _glass wound in short
spirals about the conductor in direct mi’.
ille of` this patent:
Carl et al _________ __ Aug. 26,
Hall et al _________ __ Oct., 21,
Gavitt ____________ __ Mar. 9,
Fuller ___________ __ May 30,
Slagter et al _______ _- Nov. 27,
..... __ Aw. 18. 1943
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