Improvements in Electric Insulating Devices.
Year: 1899

page_text: Date of Application, 17th Nov., 1899 -Accepted, 21st July, 1900
[Communicated from abroad by LOUIS MC CARTHY, of 416, Atlantic Avenue,
Boston, in the County of Suffolk and State of Massachusetts, United States
of America, Manufacturer.]
Improvements in Electric Insulating Devices.
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:-
The invention relates to insulators of the class comprising a metallic case,
suspending or connecting pieces placed within the same, and material, such as
mica, for insulating the said parts from one another.
When mica is employed, either comminuted or in sheets, the value and
efficiency of the insulation is increased substantially in proportion to the solidity
with which the mica is packed or compressed. Under very heavy pressure a
mass of mica may be made practically solid, so that although composed of a
large number of pieces it appears like one piece. Moisture will not pass through
such a solidified mass, it is very strong, and its insulative quality is very high.
The object of the invention is to produce insulators of the class aforesaid,
of a construction which will enable the parts of the insulators to be insulated
in a thorough and effective manner from one another by compressed or solidified
mica, and which also will enable the insulators to be manufactured quickly and
cheaply.
The accompanying drawings show by sectional views different forms of insu-
lators, all embodying the features of the present invention, and illustrating
various ways in which the invention may be reduced to practice.
The metallic case to which reference has been made is designated 1 in each
instance. It preferably is cylindrical, as shown, and is open at one end, it
usually having an aperture 2 at the other end to accommodate one of the con-
necting pieces. Fig. 9 illustrates in cross-section the original form of the shell
which is employed in the production of the particular insulator which is repre-
sented in Fig. 6, to which latter reference will be made hereinafter. Fig. 1
indicates, in dotted lines, the original form of the shell which is employed in
making the insulator of the said figure.
3 is a connecting piece having a portion thereof contained within the case.
The shape of the said connecting piece will vary in practice according to the
uses for which the insulators are intended. The connecting-piece 3 preferably
is headed, as shown at 31, and a number of sheets of mica, as at 4, which have
been cut to fit the interior of the case 1, and which are provided with central
apertures to accommodate the stem of the connecting piece 3, are strung on the
said stem next the head 31. The connecting piece and the mica sheets or disks
strung thereon are then placed within the case 1, and the space around the
head of the connecting piece and above the same is filled with a sufficient amount

page_text: of mica, as at 5, the said mica being either comminuted or in the form of sheets,
as shown, as may be desired.
A second connecting piece 6 termed usually a cap or follower is placed above
the mica 5, within the open end of the case. The shape and construction of
this cap or follower 6 varies in practice. In some forms of insulators, as for
instance those which are represented in Figs. 5, 6, and 7, mica as 7 is placed
within the open end of the shell or case 1 above the head or flange 61 of the
connector 6 and a ring 8 is placed upon the said mica 7.
In accordance with the invention, the parts described having been assembled,
they are secured together by bending inwardly the open end of the case down
upon the flange or head 61 of the connector 6 in Figs. 1, 2, 3, and 4, or upon the
ring 8 in Figs. 5, 6, and 7. In order to effect this, I place the assembled parts
of the insulator in a suitable press and there subject them to a high degree
of pressure. The parts of the press are fitted to bend or turn the open end of
the case over the edge of the head or flange 61 or ring 8. The pressure forces
the cap or follower, and also the ring 8 when it is employed, downwardly into
the case 1, thereby compressing or solidifying the mica under great pressure.
When the mica has been compressed as much as it can be by the pressure used,
the cap will come to a bearing. The end of the case, which has been gradually
bent as the cap or follower has been forced downwardly, will be turned down
smoothly over the head or flange of the cap or follower 6, when the latter is
shaped as in Figs. 1 and 2, or forming a bead when the cap or follower has a
raised portion as in Figs. 3 and 4, or when a ring 8 is employed shaped as in
Figs. 5, 6, and 7. In this way the mica insulation is not only compressed and
solidified in a very effective manner, but the cap or follower is secured firmly in
place while the mica is under compression, a tight joint being formed between
the cap or follower and the cace, the mica being held from expanding again.
The invention further consists in providing the insulator with an outer cover-
ing 9 of insulating composition, which effectively insulates the exterior portions
of the metallic parts and protects them from the effects of weather, moisture, etc.,
while it also improves the appearance of the finished article.
By way of explanation of the different forms of insulators which are shown
in the drawings, it should be stated that Fig. 1 shows a strain insulator, such as
is employed in the overhead construction of electric railways. In this figure,
the connector 3 is furnished with an eye at 311 to receive an end of one sup-
porting wire, while the connector 6 has applied to the threaded socket which is
formed in the same the threaded stem of an eye-bolt 62 to which is connected
another supporting wire. In Fig. 1 the head of the connector 3 is cylindrical,
the annular space around the said head being packed with mica as at 5, while
other mica is placed between the flat side of the said head and the inner side
of the connector 6. In Fig. 2 is shown a form of insulator which may be used for
a hanger. In this figure the head of the connector 3 is convex and the inner side
of the head of the connector 6 is concave, the head 31 being covered, and
the space below the head 61 being filled, by the sheets of mica 5, which are
caused to assume a curved shape. This is the case also in Figs. 3, 4, and 5.
In Fig. 3 the shell or case 1 is furnished with a downwardly extending flange or
skirt 11 to overhang the part which is applied to and supported by the con-
nector 3. In Figs. 3 and 5 the inwardly projecting flange of the case is brought
to a feather edge as shown, and the under side of the said flange is formed on
a curve, a series of sheets 12 of mica being strung on the stem of the connector 3
outside the said flange, and a retaining nut or washer 13 is forced on the said
stem so as to compress the mica 12 against the flange, causing it to assume
the curved position shown and lie snugly against the under side of the flange.
By reducing the flange to a feather edge the sheets of mica on the under side
of the flange are allowed to come in contact with the sheets of mica above the
flange around the stem of the connector 3. To further insure this result the
nut or washer 13 in Fig. 3 is made convex on its upper side. In Fig. 4 the flange

page_text: of the case is not reduced to a feather edge but is left of uniform thickness. In
Fig. 5 the skirt is formed with downwardly and upwardly projecting parts 14
and 15 against the inner surface of which the exterior covering 9 is moulded.
In this figure the mica at 7 insulates the connector 6 from the shell 1.
In Fig. 6 the shell 1 is perforated as at 16, 16, Fig. 9, and portions of the in-
sulating composition forming the exterior covering 9 are shown as having flowed
through the perforations and filling the annular spaces around the heads of the
connectors 3 and 6. Thereby all openings and joints within the case are filled
and sealed. In Figs. 7 and 8 each of the connectors 3 and 6 has the head and
a portion of the stem thereof encased in a covering or jacket 621 of insulating
composition. Thereby double insulation. is secured, that is to say, it is made
necessary for an electric current to pass two portions of insulation in order to
pass the insulator, the connections being insulated from each other as well as
from the case.
Fig. 10 shows a form of insulating joint for electroliers or chandeliers. In
the said figure, the lower connector 18 is formed in one piece with the case 1.
The upper connector 19 is insulated from the case by mica at 20 between the
head of said connector and the closed end of the case, and at 21 between the
upper side of said head and the bent-over open-end of the case. In this instance,
the connectors are internally threaded for application to the ends of the pipes
with which the insulator is employed. The space around the flange of the
upper connector is filled by insulating material 22, which may, for example, be
introduced, wherever air-spaces would otherwise be left, in dry and powdered
form in the process of manufacturing the insulator and subsequently be rendered
plastic and solid by the application of heat.
In Figs. 5, 6, and 7 double insulation is secured, by insulating both of the
connectors 3 and 6 from the case 1 as well as from each other.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. The improved insulator comprising essentially the case or shell, the oppo-
site connectors, and the compressed mica insulating the conducting portions of
the insulator from one another, the said cap or shell having the inwardly turned
lip whereby the parts are securely held in place and the compression of the
mica is maintained.
2. The improved insulator constructed substantially as aforesaid and having
the outer covering 9 of insulating material.
3. The improved insulator constructed substantially as aforesaid, the shell
thereof having perforations therethrough for the purpose stated, and with the
insulating material 9 forming an outer covering extending through the perfora-
tions and filling spaces within the shell.
1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.