Improvements in Insulating Joints for Metal or Armoured Conduit Tubes, more especially suitable for Electrical Conductors.
Year: 1896

page_text: Date of Application, 1st Aug., 1896-Accepted, 12th Sept., 1896
[Communicated from abroad by EDWIN TRUMAN GREENFIELD, of No. 44 Broad
Street, New York City, in the County of New York and State of New York,
United States of America, Electrician.]
Improvements in Insulating Joints for Metal or Armoured Conduit
Tubes, more especially suitable for Electrical Conductors.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, 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:-
This invention has for its object the construction of a perfect insulating joint
between the two ends of adjoining metal or armoured conduit tubes having an
insulating lining, and will be fully understood from the following description and
the accompanying drawings, in which
Figure 1 is a longitudinal sectional view of the ends of a pair of metal or
armoured conduit tubes lined with insulating material and connected by a screw-
threaded collar or nut having my improved insulating joint embodied therein.
Figure 2 is a similar sectional view showing the parts firmly screwed together so
that the interior insulating lining constitutes with the insulating joint, a perfect
.continuous insulation.
TT represent two irou armoured conduit tubes provided with a lining of
insulating material P, preferably paper, which has been treated in any well known
or suitable manner for perfecting the insulation of such tubes. The two adjoining
ends of the tubes T T are screw-threaded as shown at S S. C represents a locking
collar provided with female screw-threads S' S₁ adapted to receive the screw-
threads S, S. In the centre of the locking collar C is located a short tube or
thimble P' of insulating material and having substantially the same inner and outer
diameters as the lining P of the tubes T. The said thimble P¹ is made preferably
of hard rubber, although any other good insulating material which is sufficiently
hard may be used. In each end of the thimble is formed a V-shaped groove.
When in position, the thimble fits snugly within the central part of the collar C.
When the tubes T T are drawn toward each other by rotation of the collar C, the
inner ends of the insulating linings P P are brought firmly into contact with
the V-shaped grooves at the opposite ends of the short tube or thimble P¹ and are
caused to be firmly embedded therein and to assume the shape or conformation
shown in Figure 2 so that the interior linings P P of the tubes T T and the
thimble P constitute one insulating lining which is absolutely water-tight.
I find that with such an arrangement I am enabled to so firmly press the inner
ends of the insulating linings into the grooved ends of the insulating thimble that
most perfect insulation is effected and in the simplest possible manner.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is :-
A joint for two armoured conduit tubes, consisting of a collar surrounding a
short tube or thimble of insulating material having V-shaped grooves at its opposite

page_text: ends, said collar and armoured conduit tubes being provided with means for
connecting them firmly together under pressure so that the thimble and the lining
of the conduit tubes constitute one continuous insulating tube, substantially as
described.
Deted this 1st day of August 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.