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2,734,098 TRANSPOSITION
INSULATORS Elmer
Johannes Bonnesen, West Orange, N.J., assignor to American Telephone and
Telegraph Company. A corporation of New York Application November 30, 1950, Serial No. 198,421 4 Claims. (Cl. 174-194) This
invention relates to insulators for telephone transmission lines and
more particularly to a multiple groove composite type insulator for use
in transposing open wire lines in high quality circuits. One
object of this invention is the provision of a multiple groove composite
type transposition insulator which will have greater mechanical strength
than presently known insulators. Another
object of the invention is to facilitate the manufacture of multiple
groove transposition insulators. In
the construction of high quality open wire telephone circuits, it is a
well established practice to transpose the wires in a pair at
predetermined intervals along the spans to avoid interference between
adjacent pairs and eliminate cross-talk. At present various devices and structures are used to
accomplish these transpositions; for example point-type transposition at
cross-arms or pole supported fixtures are provided; also brackets having
insulators mounted thereon are positioned in mid-span and
multiple-groove insulators which may be supported on brackets or
suitable supports at the required transposition position are also
provided. It
has been common practice to use a multiple groove two-piece insulator of
glass or other vitreous material. This particular structure was
necessary to facilitate manufacture of an all glass or vitreous
insulator since to provide multiple-grooves therein with a suitable
skirt between the grooves to provide a long leakage path, which is
mandatory on high quality open wire lines, was not feasible or
practicable inasmuch as the extending skirt prevented the use of known
molding methods and to devise new methods would be prohibitive due to
the cost involved. It has
been known that two-piece multiple grooved glass insulators have an
inherent weakness where they are joined but since no other structures
were available they have been used but maintenance has been high due to
failure of the insulators. This
invention provides a multiple groove transposition insulator which is as
strong mechanically as a one-piece insulator and has a long leakage path
between the conductors in the grooves, and furthermore is relatively
inexpensive to manufacture. In
accordance with the preferred form of my invention, I have provided a
multiple groove vitreous insulator which has a composite structure, that
is, the main body portion is constructed from a suitable vitreous
insulating material, and the skirt portion which separates the wire
grooves and assures a long leakage path there between is constructed
from a non-vitreous material, for example wax impregnated rubber. The
invention will be understood more clearly from the following detailed
description when read in connection with the accompanying drawing in
which: Fig.
1 is an elevational view partly in section of one embodiment of this
invention, showing the structure of the skirt and its location with
respect to the wire receiving grooves; and Fig. 2 is a fragmentary view of a portion of a transmission
line illustrating one method of utilizing the insulator of this
invention. As shown in Fig. 1, the insulator comprises a body member 10 of suitable insulating material, preferably of glass or other vitreous material, having on its periphery the circumferential wire receiving grooves 11 and 12. The bottom of the member 10 is provided with the usual skirt 13 to provide a long leakage path between the insulator pin and the wires located in the grooves on the insulators. Located between the grooves 11 and 12 is a circumferential groove 14 in which is positioned a skirt member 15 which is constricted from a non-vitreous material such as wax impregnated rubber. Since the inside of the skirt member 15 has a diameter less than the diameter of
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the
insulator at the groove 14, the skirt 15 will be firmly positioned in this
groove and cannot readily be displaced. Due
to the cross-section structure at the skirt 15 and the adjacent groove 16,
a long leakage path is provided between the wires positioned in the wire
receiving grooves 11 and 12. The interior of the body member 10 is
provided with suitable internal threads 17 which are adapted to engage the
external threads of an insulator supporting pin 18, such as shown in Fig.
2, which may be of wood or metal. While
I have shown and described a preferred embodiment of my invention, it is
to be understood that various changes and modifications may be made
therein without departing from the scope and spirit of the invention. What
is claimed is: 1.
A transposition insulator for electrical circuits comprising a body member
of insulating maternal having its lower portion outwardly flared, said
body member having therein a pin receiving recess which extends from said
lower portion only partially into the body member to provide an unbroken
upper surface at the top of said body member, said body member having on
its outer surface, a pair of spaced apart circumferential wire receiving
grooves, a third groove intermediate said wire receiving grooves, and a
downwardly depending skirt of elastic Insulating material positioned in
said third groove and extending beyond the periphery of the outwardly
flared lower portion of the body member. 2.
A transposition insulator for electrical circuits comprising a body member
of insulating material having its lower portion outwardly flared, said
body member having therein a pin receiving recess which extends from said
lower portion only partially into the body member to provide an unbroken
upper surface at the top of said body member, said body member having on
its outer surface a pair of spaced apart circumferential wire receiving
grooves one adjacent the top portion of said member and the other adjacent
the flared lower portion, a third groove intermediate the upper and lower
wire receiving grooves, and a downwardly depending skirt of elastic
insulating maternal positioned in said third groove and extending beyond
the periphery of the outwardly flared lower portion of the body member. 3. A transposition insulator for electrical circuits comprising a body member of insulating material having its lower portion outwardly flared, said body member having therein a threaded pin receiving recess which extends only partially from said lower portion into the body men her to provide an unbroken upper surface at the top of said body member, said body member having on its outer surface, a pair of spaced apart circumferential wire receiving grooves, a third groove intermediate said wire receiving grooves, and a downwardly depending skirt of wax impregnated elastic insulating material positioned in said third groove and extending beyond the periphery of the outwardly flared lower portion of the body member. 4.
A transposition insulator for electrical circuits comprising a body member
of insulating material having its lower portion outwardly flared, said
body member having therein a threaded pin receiving recess which extends
from said lower portion only partially into the body member to provide an
unbroken upper surface at the top of the insulator, said body member
having on its outer surface a pair of spaced apart circumferential wire
receiving grooves, one adjacent the top portion of the insulator and the
other adjacent the flared lower portion,
third groove intermediate said wire receiving groove, and a
downwardly depending skirt of wax impregnated elastic insulating maternal
positioned in said third groove and extending beyond the periphery of the
outwardly flared lower portion of the body member. References
Cited in the file of this patent: UNITED
STATES PATENTS 1,065,737
Slonecker - - - June 24, 1913 1,795,638
Champion - - - Mar. 10, 1931 2,135,558
Bott - - - - - - - Nov. 8,
1938 2,138,571
Dehmel- - - - - Nov. 29, 1938 2,266,400
Reed - - - - - - Dec.
16, 1941 2,304,483
Smith et al. - - Dec. 8,
1942 2,31l,779
Shilling- - - - - Feb. 23, 1943 FOREIGN PATENTS 146,911
Germany - - - - Dec. 19,
1903
28,141
Denmark - - - - July 23, 1921 414,535
Germany
- - - - May 30, 1925
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