Improvements in Conduits for Electrical Conductors, and in the Mode of Making same.
Year: 1894

page_text: Date of Application, 24th Nov., 1894-Accepted, 29th Dec., 1894
COMPLETE SPECIFICATION.
Improvements in Conduits for Electrical Conductors, and in the
Mode of Making same.
I, JAMES TATHAM, of 226, South Fifth Street, in the City of Philadelphia,
State of Pennsylvania, United States of America, Lead Pipe Manufacturer, do
hereby declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
My invention relates to the manufacture of conduits for electric conductors of the
kind described in the Specification No. 20288 of 1889, the object of my present
invention being to facilitate the manufacture of such a conduit especially when the
same is of comparatively small diameter and of considerable length.
The conduit above referred to consists of inner and outer metallic tubes and an
interposed layer of insulating material rigidly confined between the two tubes. It
is manufactured by first introducing the tube of insulating material within the
outer tube then inserting the inner tube and finally expanding the whole by internal
hydraulic pressure.
This method of manufacture is comparatively slow and limited to conduits of.
short length and of considerable diameter.
My new process has been devised especially for the manufacture of conduits of
small diameter and of indefinite length such as are used for leading wires for electric
lighting and other purposes through buildings.
The accompanying drawing represents my improved conduit, partly in section.
I first make the inner tube d of lead or other ductile metal in an ordinary lead
pipe press and I then apply to it the insulating covering b, preferably by winding
or braiding cotton, yarn or thread upon it and, if desired, saturating it with fluid
insulating material which sets.
The tube with its insulating covering is continuously fed from a reel or other
holder through the hollow core of another lead pipe press whereby the outer tube a
is applied to the insulated covering of the inner tube.
In
I prefer to use for this purpose a machine of the kind described in the Specifi-
cation No. 7188 of 1887 as such a machine provides for saturating the insulating
cover of the inner tube with liquid insulating material almost up to the point of its
issue from the nose of the core before passing through the die of the press.
some cases this saturation of the textile covering of the inner tube may render
previous saturation unnecessary; or, if the textile covering is previously saturated
with insulating material, the hollow core of the second lead pipe press need not
be supplied with the liquid insulating material. I prefer however to the covering
with insulating material in the second press even although it may be previously
saturated.
As the lead tubes are flexible to a certain extent, the conduit can be readily
bent to turn corners, or otherwise conform to the crooked course which electrical
conductors frequently have to take in internal installations. In this respect the
conduit now described differs from that described in my previous Specification in
which the metal tubes were both rigid.
After the conduit has been made as described, its ends are by preference flanged
or expanded as shown in the drawing so as to provide for connecting successive
lengths

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The herein described manufacture of a conduit for electric conductors, by
making a tube of lead or other ductile metal, applying thereto an insulating
covering, and then forming an outer tube of lead or other ductile metal around the
insulating covering.
2. A flexible conduit for electric conductors, consisting of inner and outer tubes
of lead or other ductile metal, with interposed insulating material rigidly confined
between these tubes, substantially as specified.
Dated this 24th day of November 1894.
ABEL & IMRAY,
Agents for Applicant.