Improvements in the Underground System of Electric Traction.
Year: 1893

page_text: Date of Application, 27th June, 1893-Accepted, 23rd Sept., 1893
COMPLETE SPECIFICATION.
Improvements in the Underground System of Electric Traction.
1, JOHN ALEXANDER KENNEDY MCGREGOR, of No. 225 Dearborn Street,
Chicago, County of Cook and State of Illinois, United States of America,
Electrical Engineer, 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 systems of underground electric traction for railways,
and it has for its object the provision of reliable means for automatically con-
necting into circuit with an electric generator, sections of the conductor over
which the car is passing, said sections being automatically switched out of circuit
The electric
again when the car has passed on to the next section of track.
circuit is thus exposed only on the sections on which the car may be passing or
standing,
My invention consists of a special form of switch and switch chamber, and in
the method of suspension of the sectional conductor in combination with the
double trolley adapted to make contact with said sectional conductors and carry
the current to the motor upon the car, and at the same time to operate the
switches at the junctions of the sections.
The accompanying drawings illustrate my invention.
Fig. 1 is a side elevation of a car with the apparatus of my invention in place,
showing a diagram of the electric circuits connected therewith.
Fig. 2 is an end elevation of a portion of a car partly in section, with an end
elevation of the apparatus of my invention in place.
Fig. 3 is a sectional view of the trolley arm.
Fig. 4 is a diagrammatic illustration of my invention with its electrical circuits.
Fig. 5 is a top view of the special switch which I use, with the cover removed.
Similar letters of reference indicate similar parts throughout the different views.
Through the motor a upon the car a' the circuit passes to the wheel of the car
and thence to ground through the rail in the well known way, as shown by the
dotted line in Fig. 1. The circuit from the conductor b is through the trolley c
and its arm c¹ to the rheostat c³ and to the motor, as also shown by the dotted line
in Fig. 1. The rheostat is of well known construction adapted to control the
amount of current delivered to the motor, and as it does not constitute an essential
feature of my invention, it does not need further description.
This
The trolley arm c¹ is linked and electrically connected at e³ by two pins which
may be withdrawn, thus allowing the lower part of the trolley arm to pass below the
floor of the car platform and permitting the car to pass on. The trolley arm is
Bupported by the stop d which rests upon the coiled spring d supported within a
cylinder d. This cylinder d' is supported upon the pin d³ which rests in bearings
in the forked handle d' and serves as a pivot upon which such handle turns.
construction of the handle enables the operator to raise the trolley arm until the
trolly is in contact with the conductor. The frame or casing through which
said handle passes is provided with an opening which permits the handle to
pass freely when held vertically. When the handle is raised until its forked
members d d entirely emerge, the handle may be turned and will thus rest upon
the top of said casing, as shown in Fig. 1. The trolley is then supported upon the
trolley arm which is given an elasticity by means of the coiled spring, thus com-
pensating for any irregularities in the track or in the height of the rail, and always
insuring a good, though yielding, contact between the trolley and the conductor.
By the conductor d' I connect the trolley arm with the rheostat.
I preferably make the trolley arm of an inside conductor e surrounded by some

page_text: suitable insulating substance e', outside of which I put a casing, preferably of iron,
as an armour for same. I have shown in Fig. 3 a form of casing which I prefer to
use on account of its convenience and cheapness. It consists of two L shaped
pieces of iron placed together to form a case surrounding the insulated trolley
conductor.
The two trolleys ff are both connected electrically with the trolley conductor,
but each one is mounted so as to rotate separately upon the end of the trolley
arm which is extended at right angles to Faid arm. These trolleys are so placed
that they engage with two series of conductors placed parallel with each other.
These series of conductors gg are in sections. The end of each section of one
series overlaps the end of the next succeeding section of the adjoining series, as
shown in Figs. 4 and 5. The ends of each section are cut away, as shown, in
such a manner as to insure the contact of one trolley with each succeeding section
before the other trolley has left the preceding section of the adjoining series.
This construction also prevents the sectional conductors making a too abrupt
contact with the trolley. As the two series of conductors are supplied with
current successively through the switches from the main feed wire l, as hereinafter
described, it is obvious that the interior conductor of the trolley arm is constantly
supplied with current through one or the other of the trolleys.
The sectional conductors are suspended upon the hollow arms i¹, which I
preferably make of gas pipe and through which I lead conducting wires to be
attached to the sectional conductors. These arms are hung in bearings in the
casing which incloses the junction switch, and they carry on the extremities
inclosed within said junction boxes the switch arms ² k² adapted to make contact
with the contact plates 3 k, with which the main lead wire is connected.
I preferably split these contact points and fit the switch arm to make contact by
pressing into the space between the two split portions, thus insuring a positive
contact of low resistance.
The bearings in which the arms i i¹ rest in the junction switch casing I preferably
make somewhat thicker than the rest of the casing so as to give the arm a broader
bearing surface. By making the arms fit snugly in these bearings and by
thoroughly sealing the chamber inclosing the switch contacts, I make the junction
box moisture proof so that it may be placed in any position no matter how exposed,
without impairing the operation of the switch.
The arms are bent in such manner that any motion of the end attached to the
conductor in a vertical direction will result in a rocking motion of the arm in its
bearing. I preferably bend the arm twice at right angles, as shown, to accom-
plish this.
It will be observed that the switch levers attached to arms ii are adapted, one
to make contact with switch plate k³, by an upward movement, the other to make
contact with switch plate by a downward movement. One series of conductors
I attach to arms, the other series of conductors I attach to arms i. The
connection between the arm and the conductors is insulated in any suitable way.
The switch levers k² k² are rigidly but detachably connected to the extremity of
the arms inclosed within the junction box. The connection between the main
lead wire and the switch connecting plates and are made by insulated wires,
and the contact plates themselves are suitably insulated from the case inclosing the
switch mechanism.
I will now proceed to describe the operation of this apparatus :
Referring to Fig. 4, the current is led from the dynamo m over the main lead
wire 1, from which branches lead to the contact plates ³ of the switch. The
trolley bearing against the conductor g raises this conductor sufficiently to rock
the armi in its bearing, thus closing the switch lever with contact k³, the current
then passes from the dynamo through the main lead wire and by branch wire to the
contact plate, and thence by the switch arm and the conductor in the interior of the
arm to the sectional conductor g, whence it is taken up by the trolley and
delivered to the motor on the car. As the trolley f passes the junction box, the

page_text: other trolley of the pair comes in contact with the sectional conductor of the
adjoining series, and on doing so, lifts the conductor, thus rocking the arm i in
its bearing and bringing switch lever k² in contact with plate k³.
It will be observed that the construction of this apparatus is such that the trolley .
passes to, makes contact with, and raises the next succeeding sectional conductor
before dropping the conductor which it is about to leave. This construction prevents
arcing at the contact points. The circuit of any section is not opened until the
circuit is closed through the next succeeding section.
The construction which I have adopted, which consists in suspending the sectional
trolley conductors so that they will swing in vertical planes coinciding with their
lengthis, and so that motion imparted to said sections, either in a longitudinal or
vertical direction, will be made operative in closing a switch connecting said
sectional conductor with the supply wire leading from the conductor, while the
weight of said sectional conductor operates to keep said switch normally open, is
new I believe. I also believe that it is original with me to make a trolley
conductor in sections suspended so that they will swing through arcs of circles in
vertical planes coinciding with their lengths, and while this construction is specialty
applicable to the system which I have described herein, in which said swinging
sections operate a switch for the purposes set forth, I do not wish to limit my
invention to that particular combination.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
1. A trolley conductor comprising sections suspended upon swinging arms
adapted to move in vertical planes coinciding with the planes of said sections,
said sections being placed in parallel overlapping series, substantially as described.
2. A switch in combination with the supply conductor and a horizontal trolley
wire section, said section being adapted to be raised by the trolley passing under
the same and a swinging arm or support extending from the switch to the section,
said support being adapted to close the switch to make connection with the supply
conductor when the section is raised, substantially as specified.
3. The combination in an electric railway system, of the supply conductor
with a trolley conductor, said trolley conductor consisting of two parallel series of
sections, each section of the different series overlapping the preceding and next
succeeding sections of the adjoining series, and a trolley having two sheaves or
rollers mounted on the same shaft and connected with a common conductor leading
to the car, said sheaves being adapted each to press against the sections of a
particular one of the series.
4. In an electric railway, the combination with a sectional trolley conductor
suspended upon swinging arms and adapted to move in a vertical plane coinciding
with its length, of switches adapted to be operated by said arms, whereby motion
imparted to said conductor in a longitudinal or vertical direction results in con-
necting said conductor into circuit with a supply wire lending from a generator,
while the weight of said conductor operates to keep the switch normally open,
substantially as described.
5. In an underground electric conduit system, the two series of sectional con-
ductors suspended upon swinging arms adapted to move in vertical planes coinciding
with the planes of said sectional conductors, in combination with trolleys adapted
to engage successively with said sectional conductors, and to automatically operate
a switch, and said switch which operates to close the circuit through each succeeding
section of the conductor before it opens the circuit through the preceding section,
substantially as described.
6. In an underground electric conduit system, sectional conductors arranged in
adjoining series of sections, each section overlapping the next preceding and
succeeding sections of the adjoining series, and suspended upon rocking arms to
which are connected switch levers adapted to make contact with the plate con-

page_text: nected with the main lead wire, whereby when said sectional conductor is raised,
connection between the sectional conductor and the main lead wire is made,
substantially as described.
7. In an underground electric conduit system, the junction box adapted to
connect the main circuit successively to the sectional conductors, in combination
with swinging arms adapted to move in vertical planes coinciding with the planes
of said sectional conductors and to support the said sectional conductors, said
sectional conductors being normally out of connection with the main lead wire, but
being adapted to be brought into connection therewith by being raised or swung
by a trolley attached to the car, and to be restored to its normal position upon the
trolley leaving said section, substantially as described.
8. In an underground electric conduit system, the combination with the generator
of the main circuit leading therefrom, said main circuit being branched to junction
boxes which are adapted to close the circuit between said main lead wire and
sectional conductors suspended upon arms which have bearings in the sides of said
junction boxes and are adapted to rock therein, said sectional conductors adapted
to be moved in a vertical plane through the arc of a circle when lifted by a trolley
attached to the car, whereby said main circuit is connected successively through
the sectional conductors with which the said trolley is in contact, thence through
the trolley to the motor upon the car, and thence to ground, the other sections of the
conductors not being in the circuit, substantially as described.
9. In an electric underground system, the combination with sectional conductors
overlapping a short distance at their ends and lying alternately in two parallel
lines, of independent trolley wheels adapted to travel one along each of said lines
and to alternately make connection with the sections of said lines, said trolley
wheels being both electrically connected with a trolley arm adapted to lead the
current to a motor placed upon the car, whereby said trolley wheels may engage
sections upon the two lines alternately to supply a continuous current to the motor,
substantially as described.
Dated this Third day of June A.D. 1893.
JOHN ALEXANDER KENNEDY MCGREGOR.