Improvements in or relating to Insulators for the Support of Overhead Electrical Conductors.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to Insulators for the Support of
Overhead Electrical Conductors.
I, MATHEUS NOGUEIRA BRANDÃO, Engineer, resident of Campos, in the State
of Rio de Janeiro, Republic of Brazil, 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 an improved construction of insulating attachment for
the support of overhead electrical conductors, consisting of an inverted double
bell of porcelain, or other suitable dielectric, which is cemented on to the end of
an elbow shaped wrought iron bracket that is fixed to the post. To the top of
the insulating bell is cemented a metal cap on which are fixed or formed two studs,
and on these studs are mounted two cams or eccentric segments with grooved edges,
so formed as to nip between them the wire conductor. The upper ends of the
studs are formed with screw threads, the one being right handed and the other
left handed, and upon these are screwed nuts. Thus on a conducting wire being
introduced between the grooved edges of the cams and drawn tight with the
required amount of tension, the effect of the pull on the wire will be to tighten
the grip of the cams upon the wire so as to cause them to hold it securely and
effectually prevent any slip, and when such grip has been effected, the nuts are
screwed down so as to firmly secure the cams in that position so that each section
of conducting wire between two supports will be held by the above means with
the tension originally put upon it, quite independently of the tension of the other
sections.
My said improved construction of insulator is shewn on the accompanying
drawing, in which
Fig. 1 shews a front view of the insulator and bracket,
Fig. 2 shews a sectional side elevation,
Fig. 3 shews a plan,
Figs. 4 to 7 shew details.
The double insulating bell A is secured by cementing on to the end of the
elbow shaped wrought iron bracket B, which is secured to the metal post D by
the clamping device shewn at Fig. 4, the end of the bracket being formed with
flanges B, through which pass screw bolts E also passing through a plate F, on
the other side of the post, so that on screwing up the nuts of the screw bolts the
bracket is firmly clamped to the post. When a double bracket is employed these
are arranged as shewn at Fig. 5.
When wooden posts are used the end of the bracket may either be formed with
a wood screw thread as at Fig. 6, for screwing into the wood, or it may be formed
as a screw bolt and passed through the post and be secured by a nut as at Fig. 7.
By forming the bracket B of a single elbow shaped piece of wrought iron
instead of making it of two pieces as is generally done, simplicity of construction
is attained, and the inconvenience that frequently occurs in transport is obviated it
being often found that the numbers of the rods supplied that carry the insulators
does not correspond with the numbers of the horizontal arms or brackets which
carry such rods.
On the cylindrical top part of the insulator A is cemented the metal cap G, to
which are fixed two studs HH, and on these are placed loose the cams or
eccentric segments II with grooved edges; the ends of the studs are formed
with right and left handed threads, on which are screwed nuts J J.
The conducting wire K having been passed between the cams II, and a strain
put upon it in the direction of the arrow Fig. 3, it will be seen that the cams, by

page_text: the frictional contact of their roughened grooves with the wire, will turn upon the
studs H H so as to grip the wire with increasing force, and if, when the desired
tension has been attained, the nuts J are screwed tightly down so as to secure the
cams in the position which they have been made to assume, it will be seen that
they will securely hold the wire against shifting in either direction, the threads of
the studs being in that direction in which the nut would tend to screw up tighter
if the cams tended to turn in the direction for loosening their grip on the wire.
Thus each section of the conducting wire between two supports will be held
with the tension originally put upon it, quite independently of the tension existing
in the contiguous sections, so that should any expansion of the wire by heat take
place such expansion cannot result in the wire sagging down to a considerable
extent at one section owing to the slack of the wire in the contiguous sections
being, from some cause, shifted into that section, as frequently occurs in existing
modes of fixing.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, declare that what I
claim is :-
1. An insulating attachment for electric conductors, consisting of the com-
bination of a double insulating bell of ordinary construction, a metal cap cemented
to the top of the bell carrying two studs, two cams or excentric segments fitted
loose on the said studs for gripping the conducting wire between them, and screw
nuts screwing on to the threaded ends of the studs for securing the cams in the
positions in which they grip the wires, substantially as described.
2. The combination with the insulator referred to in the preceding claim, of a
supporting bracket formed of an elbow shaped piece of wrought iron to one end of
which the insulating bell is cemented while the other end is adapted to be fixed to
the post either by forming it with a screw thread for screwing into a wood post, or
as a screw bolt and nut for passing through the post, or as a clamp for clamping on
to the post, substantially as described.
3. The use for securing electrical conductors on their insulating supports of two
cams or excentric segments fitting loose on two fixed studs and adapted to grip the
conductor between their groove edges, the said cams being secured in the position
in which they grip the conductor by means of screw nuts screwed on to right and
left handed screw threads on the said studs so that on the cams tending to turn in
the direction for loosening their grip, they tend to turn their nuts in the tightening
up direction, substantially as described.
4. The herein described construction of insulating attachments for securing
overhead electrical conductors by means of nipping cams or eccentric segments
whereby each section of conductor between two supports is held permanently with
its initial tension independent of the tension in the contiguous sections of the
conductor, substantially as described.
ABEL & IMRAY,
Agents for the Applicant.