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Патент USA US2137067

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Nov. l5, 1938.
l.. c. SPENCER
Filed June 26, 1936
¿,027 SiS/vencer:
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Patented Nov. 15, 1938
Lon G. Spencer, Indianapolis, Ind.
Application June 26, 1936, Serial No. 87,359
9 Claims.
My invention relates, generally, to overhead
trolley systems, and it has reference in particular
(Cl. lill-_39)
the necessary strength, the construction of a
section insulator becomes decidedly bulky when
to section insulators for overhead trolley sys-
Generally, it is desirable to sectionalize the
power supply for overhead trolley systems. That
is, instead of having one continuousI overhead
trolley line with power supplied from a number
of sub-stations, the trolley line is sectionalized,
110 each section being insulated from the other and
fed through a separate feeder. In this way,
should a fault such as a grounded trolley wire
occur in one section, the other sections will not
be affected.
Continuity of service is thus im-
`15 proved, and also amore balanced loading of substations is secured, as the length of line which
hickory is used.
Resinous compounds have been used as insu
lating material in section insulators, but while `5
they have good electrical qualities, they do not
have the mechanical strength to withstand the
high stresses imposed upon them. In some cases,
rubber compounds have been used but while they
have both the desirable mechanical and electrical 10
properties, their cost is excessive, as also is their
It may, therefore, be seen that with the con
tinued rapid growth of trolley-bus systems, and
with the increasing scarcity of hickory as an 15
insulating material, there is a decided need for
any one sub-station may feed is limited.
some new material or combination of materials
In trolley bus power systems, both the positive
and negative conductor must be carried over-
to give an insulator the desired electrical and
mechanical qualities.
The object, therefore, of my invention is to 20
provide a high strength, single beam section in
sulator which will have high resistance to the
deleterious effects of exposure to moisture.
Another object of my invention is to provide
a super-rigid single beam section insulator that 25
shall not swell, buckle or warp under the most
adverse weather conditions.
A further object of my invention is to provide
a super-rigid section insulator having renewable
wearing parte
Another object of my invention is to provide
a section insulator having an insulating member
with a metallic core of magnetic material, which
fune'ßiOIlS' t0 greatly reduce or prevent the burn
20 head as there is no ground return, the bus being
insulated from the ground by rubber tires. This
greatly complicates the construction of the overhead trolley at intersections, as it is necessary to
provide insulating means between the conductors
v25 of opposite polarity where they intersect. This
is usually accomplished through the use of section type insulators together with the necessary
interlocking end fittings, and the usual metallic
frogs or crossings.
„3o lAs such an insulator is inserted directly into
the line, it must withstand the full tension of
the conductor, which may amount to from 2000
to 4500 lbs. This necessitates that the insulators
not only have good dielectric qualities but also
k35 have a high tensile strength. In addition, as
the insulator is directly exposed to the effects
of the weather, a further requirement is that it
be unaifected by moisture, heat, cold, etc.
These factors make the selection of a material
40 for the body of a section insulator a difiicult
matter. Fiber, which has been used to a great
extent, is a good insulator and has a high tensile
strength, but in applications where continually
subjected to moisture, such as in locations along
`4.5 the seacoast, it has shown a decided tendency
to swell. In some installations the swelling has
been so serious as to hinder the passage of the
current collector. Further exposure to moisture
has resulted in a warping and buckling of the
.50 body member, and in many cases, complete failure through softening of the fibers.
‘ Hickory, which is one of the best insulators,
is rapidly becoming scarce, and even the best
hickory when impregnated is in time decidedly
vt5 affected by weathering. Also, in order to secure
ing 0f the insulating member by the arc.
Still another object of my invention is to pro
vide a weather proof super-rigid beam section
insulator that shall be protected from the de
structive effects of arcing.
A still further object of my invention is to 4o
provide a single beam section insulator having
a core of interlocking metal strain plates molded
in an insulating material and renewable insu
lating wearing parts designed to protect the
main body from destructive eiîects of arcing.
Other objects will in part be obvious and in
part appear hereinafter.
My invention, accordingly, is disclosed in em
bodiments hereof shown in the accompanying
drawing, and comprises the features of construc- i' 0
tion, combination of elements, arrangement of
parts which will be exemplified in the construc
tion hereinafter set forth, and in the scope of
the application of which will be indicated in the
appended claims.
For a more complete understanding of my
invention reference may be had to the following
detailed description, taken in connection with
the accompanying drawing, in which:
Figure l is a partially-sectionalized plan view
of a trolley section insulator embodying the
principal features of my invention, showing one
preferred method of construction.
Fig. 2 is a side elevational View of the section
10 insulator of Fig. 1.
Fig. 3 is a sectional view taken along the line
III-III of Fig. 2, and
Fig. 4 is an end elevational view of Fig. 2.
Referring more particularly to Figs, 1 and 2,
the reference character I0 denotes a beam section
trolley insulator embodying my invention. The
insulator IU comprises generally a> longitudinal
beam insulating member II having end fittings
I2, such as shown, of well-known construction,
secured thereto for engaging adjacent ends of
It appears that under normal operating con
ditions section insulators are exposed to serious
arcing as the current collector leaves the line
section of the conductor. This arcing is usually
most destructive not only to the end fittings of
the insulator but to the insulating member also.
With a section insulator embodying my inven
tion, however, it has been observed that such an
arc may be drawn and the end fittings may even
be severely burned, without any appreciable dam
age resulting to the insulating member where
the strain members are of a magnetic material.
It is therefore obvious that the inclusion in the
vicinity of the arc of the magnetic material of
the reinforcing members has certain desirable
effects, tending to draw the arc out, cool it, and
reduce its harmful burning effects.
It may be seen, therefore, that my invention
provides a single beam section insulator which
not only combines high tensile strength, high
a trolley wire I3 or other well known forms of
insulating value and immunity to moisture, but
In one form of my invention, in order to secure
which uses well known fittings, is easy to manu
the necessary tensile strength and insulating
Since certain further changes may be made
in the foregoing construction, and different em 25
bodiments of the invention may be made without
departing from the scope thereof, it is intended
that all the matter set forth in the foregoing de
scription or shown in the accompanying draw
ing shall be considered as illustrative and not in 30
qualities, the beam I I may comprise both insulat
ing material and metallic members formed as a
unitary member. In this instance, the beam II
comprises similar metallic strain members I5
which fimction as a metallic core for the beam
3o and through which the bolts I6 extend to secure
the end iittings I2 in position.
As will be readily understood, the metallic
members I 5 must not only be securely joined to
gether but must be insulated from one another.
135 They may be jointed together by means of a
facture, and inexpensive to maintain.
a limiting sense.
I claim as my invention:
1. A single-beam section insulator for over
head trolley systems, comprising, in combination,
a main insulating member formed with a pair 35
joint comprising two complementary beveled
of similarly shaped relatively thin interlocked
surfaces having a plurality of interlocking mem
metallic reinforcing members therein, the in
sulating material of said insulating member being
bers thereon, such as the flaring tenons I 1.
These surfaces are so disposed that the tenons Il
of the one strain member I5 are positioned in the
grooves I8 of the other strain member. Suitable
insulating material I9 is interposed between the
interlocking tenons I'.' and grooves I8 to main
tain the strain members I5 in fixed relation and
45 insulate them from each other.
'I‘o aid in binding the strain members I5 to
gether and to protect the insulating material I9
from exposure to the weather, an enveloping in
sulating shell 2| may be provided _about the in
tei-locked strain members I5 in any suitable
manner, such as by winding impregnated paper
formed about and between said reinforcing mem
bers to secure them in fixed relation with each
other, end means secured to the main member
disposed to secure adjacent ends of a trolley wire,
and a renewable wearing surface and arcing shield
having outwardly Iiaring sides detachably secured
about the under side of the insulating member. 45
2. A beam insulator for overhead trolley sys
tems comprising, in combination, an insulating
main body member having a pair of similar re
enforcing metallic members oppositely disposed
in spaced relation and separated and enveloped 50
by an insulating sheath to provide a unitary
or cloth about them under pressure from heated
body member, end fittings for securing the main
body member in operating relation in the over
head system, and a removable arcing shield and
wearing surface secured about the runner edge 55
of the main body member.
3. A beam insulator for overhead trolley sys
tems comprising, in combination, an insulating
body member having a pair of similar overlapping
reenforcing members of magnetic material dis 60
posed within said body member in parallel spaced
This provides a unitary beam structure
having the necessary strength and insulating
55 qualities.
In order to relieve the body member II from
wear and the destructive effects of arcing, an
insulating sheath 22 may be detachably secured
60 to the lower side of the body member II in any
well known manner, such as by insulating bolts
23 passing through the body member II .
The insulating sheath 22 may be formed in
any desirable manner, such as a U-section 'chan
65 nel having iiaring sides which tend to disperse an
arc away from the body member as it rises, thus
protecting the body member II from the burning
effects of arcing.
It has been observed that a section insulator
70 of a type embodying my invention has shown
additional advantages.
Where the metallic
strain members of the insulating member have
comprised a magnetic material, such as iron, im
proved electrical performance as well as me
chanical strength has resulted.
relation, a laminated sheath of fibrous insulating
material formed about and between said members
to provide a unitary structure, end members se
cured to the body member adapted to position 65
said body member, and a fixed wearing sheath re
movably secured about the under side of the
body member to provide a renewable wearing
surface and an arc shield for said body member.
4. In a single beam insulator for trolley sys 70
tems, in combination, a main insulating body
member including a pair of thin tapered inter
locking metal plates overlapping in opposed re
lation, insulating material between the plates
disposed to hold them apart to maintain them in 75
ñxed relation to each other, a plurality of layers
of impregnated fibrous insulating material mould
ed about said plates, and detachable end means
secured to the body member disposed to position
Ul said body member in the trolley system.
5, In an insulator of the single beam type, in
combination, a body member comprising a pair
of interlocking end plates, insulating material
disposed between the end plates to hold them
10 apart, and a shell of insulating material disposed
about the plates, terminal members secured to
-each end plate disposed to engage adjacent ends
of a trolley wire, and a renewable sheath of in->
sulation disposed to provide a wearing surface and
arc-shield secured to one edge of the body mem
6. An insulator of the single beam type for
trolley systems comprising, in combination, a
main insulating body member including a pair
of tapered interlocking metal reenforcing end
plates formed within the body member and sepa
rated by the insulating material of the member,
end means secured to the body member for posi
tioning said body member in a trolley system, and
25 a renewable under-run and arc-shield having out
wardly inclined upstanding edges adapted to en
close an edge of the main body secured about the
lower edge thereof.
7. An insulator of the single beam type for
trolley systems comprising, in combination, an
insulating main body member having a pair of
similar tapered metallic reenforcing members dis
posed therein in insulated interlocking relation to
relieve the insulating material of incident strain,
end means secured to the ends of the body mem
ber adapted to position the insulator in the trolley
system, and a renewable wear portion and arc
shield having outwardly flaring upstanding sides
secured about an edge of the body member.
8. A section insulator for trolley systems, corn
prising, in combination, a main insulating mem
ber having a reenforcing core of overlapping
metal strain plates so disposed within the main
member and insulated from each other that the
insulation of the insulating member surrounds
said strain plates and maintains them in fixed
relation with each other, means secured to the 15
ends of the main member disposed to position the
body member in a trolley system, and a detach
able wearing sheath and arc-shield secured to
the under side of the main member.
9. A section insulator for trolley systems com 20
prising, in combination, a longitudinal insulat
ing beam member of at least two overlapping and
interlocking metal plates separated by and en
veloped by an insulating material disposed to in- `
sulate the plates from each other and to main
tain them in ñxed relation, end means secured
to the beam member for engaging adjacent ends
of `a trolley wire, and a sheath of insulating ma
terial detachably secured to the lower edge of the
beam to provide a renewable wearing surface and 30
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