Improvements in Insulators for Electric Wires.
Year: 1893

page_text: COMPLETE SPECIFICATION.
[Communicated from abroad by WILLIAM BRISBANE RAND, of 42, Magnolia
Street, Boston, County of Suffolk, State of Massachusetts, United States of
America, Broker.] .
Improvements in Insulators for Electric Wires.
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:-
My invention has for its object to provide an improved insulator for electric
wires, and it relates more particularly to insulators for indoor construction, such as
those which are employed for supporting and insulating wires which are carried
through buildings and the like. It is desirable that insulators employed for this
purpose should be of high insulative quality, and should be strong and durable and
of tasteful appearance; and they should be so constructed that the wires may be
readily placed therein or removed therefrom. These objects I attain by means of
the insulator hereinafter more fully described.
I have shown my invention in the accompanying drawings and will refer to said
drawings in the following description.
In the drawings,
Figs. 1 and 2 are respectively a side and plan view of my improved insulator
adapted to receive one wire.
Figs. 3 and 4 are similar views of a two wire insulator.
Figs. 5 and 6 are similar views of a three wire insulator.
Fig. 7 is a section on line 7-7 of Fig. 6.
The insulator may be made of any suitable insulating material. I prefer, however, to
make it of porcelain, which is first moulded to shape and then baked or fired in the well
known manner. The exterior shape or contour of the insulator is not essential. I
prefer, however, the general shape shown in the drawings, which, as will be obvious,
will vary somewhat as the size of the insulator varies, according as it is given
capacity to carry one, two or more wires. The opening to receive the wire is shown
at A, said opening being curved, as indicated in the plan views. In case, however,
it is desired that the wire shall play through the insulator, that is, be capable of
lengthwise or end wise movement, the recess or passage A will be of such a size and
shape as to facilitate the play of the wire. To this end the recess or passage A
may be nearly or quite straight. The opening A is formed by two walls a, b,
which are preferably upwardly tapering or inclined slightly away from each other
so that the top of the opening which first receives the wire when it is put in place
is somewhat wider than at the bottom thereof; this facilitates the insertion of the
wire. The narrow wall or retaining point 6 which forms one side of the opening A
is provided with an overhang so that when the wire is pushed into the
opening A to the bottom of the same, it may be straightened partially, lying in part
under the overhang b', and is thus prevented from being accidentally displaced. The
wire can be withdrawn from the insulator only by bending it somewhat and then
lifting it out of the opening A.
The overhanging projections or portions are moulded into shape at the same time
with the other portions of the insulator.. This is necessary in order that the latter
may be produced economically. If such projections or portions were not thus

page_text: produced, the insulator would require to be formed by cutting and could not be
manufactured at a sufficiently low cost. The whole insulator, including the over-
hanging projections, may be produced by moulding in either of two ways. Thus,
the upper portion or portions containing the overhang or overhangs may be moulded
separately from the rest of the insulator, and be affixed thereon prior to the baking.
Or the entire insulator may be moulded in one piece in a mould of proper form
which is provided with pins or projections located and arranged properly to extend
through the base portion of the insulator and produce by their free ends the
recesses or indentations which are underneath the overhanging projections. In
my improved insulator but one overhang is provided for each wire passage, and
that is located at one side of the said wire passage and over the central portion or
body of the insulator, and thus the aperture in the body of the insulator which is
produced by that projection of the mould which is utilized in the formation of the
said overhang is made in the central portion of the said body. Such aperture is,
therefore not likely to weaken the insulator, as would be the case if the apertures
for the mould projections were at the outside of the insulator, at each end of the
wire passage. Holes 9 are provided for the reception of screws or similar fastening
devices by means of which the insulator may be securely fastened to a wall or
similar object. In the construction of my insulator having the central overhanging
portion, sharp corners may be avoided, these latter tending to wear the wire
covering. In the manufacture of these insulators from material such as porcelain,
for example, which requires to be baked or fired, the process of firing tends to
cause the material to warp so that it frequently happens that the bottom or back of
the insulator is not perfectly level or flat, but is bowed up somewhat in the middle,
so that when the insulator is placed against the wall it will bear only at the ends
and the screwing home of the securing screws will crack the insulator crosswise. It
is desirable that the back or bottom of the insulator should not bear on the wall at
the ends to any greater degree than throughout the central portion and unless it is
absolutely flat, a condition which is difficult to obtain, it should bear rather more at
the points where the screws pass through so that there will be no danger of bringing
the pressure of the screws on the insulator in such a way as to cause it to break.
To provide for this, I bevel the bottom of the insulator slightly at the ends, as
shown at and the central portion of the insulator between the end parts k may be
slightly cut away if desired as shown at m. The insulator is strong enough through
this central portion to permit of its being somewhat cut away and the cutting away
saves a slight amount of stock. It will be noted that in my construction the ends
of the walls on one side of the openings A are slightly inclined, as shown at h, in
the same way as is the wall itself throughout its whole extent, but the incline is
somewhat greater at the ends. This is an advantage in the insertion of the wire
and tends to prevent its covering being frayed or damaged in the act of inserting it
into or withdrawing it from the insulator.
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 :-
1. An insulator for electric wires having one or more openings to receive the
wire, said openings being curved and having each a single overhang and that
overhang being on one side thereof, substantially as and for the purposes set forth.
2. An insulator for electric wires having one or more openings to receive the
wire, said openings being curved and having each a single overhang and that over-
hang being on one side thereof, the walls of the said openings being bevelled
substantially as and for the purposes set forth.
3. An insulator for electric wires having one or more openings to receive the
wire, said openings having each an overhang on one side thereof located over the
central portion or body of the insulator, whereby the aperture for that portion of
the mould which supports the overhang in moulding is in the central portion of the
body of the insulator, substantially as and for the purposes set forth.

page_text: 4. An insulator for electric wires having one or more openings to receive the
wire and having the bottom thereof bevelled at each end whereby when the
insulator is secured in position the central portion of the insulator will come to a
bearing on the support before the end portions thereof, substantially as set forth.
Dated this 23rd day of December 1893.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.