Improvements in Effecting the Electric Propulsion of Tramcars and Apparatus therefor.
Year: 1890

page_text: Date of Application, 22nd Apr.. 1890
Complete Specification Left, 21st Feb., 1891-Accepted, 18th Apr., 1891
PROVISIONAL SPECIFICATION.
Improvements in Effecting the Electric Propulsion of Tramcars and
Apparatus therefor.
I, JOHN GORDON, of Berlin, at present residing at 4, Wellington Street,
Islington, in the County of Middlesex, Electrical Engineer, do hereby declare the
nature of this invention to be as follows:-
This invention relates to an improved method of, and apparatus for, transmitting
electrical energy from a fixed station where such energy is generated, transformed
or stored, to a distant car, the propulsion of which is required to be effected by
means of an electric motor carried by the car.
For this purpose, I employ a modification of what is now generally known
amongst electrical engineers as the 'sectional rail system'; my improvements affording
increased economy in the cost of installation, greater efficiency and certainty in
working, and ensuring safety to the ordinary road traffic.
A tramway laid according to my invention comprises rails of the ordinary
description whereon the wheels of the tramcar run, and a supplementary rail, bar
or plate, laid in the track, preferably between the permanent way rails, and serving
to transmit electrical energy, through collectors attached to the tramcar, to an
electric motor carried by the car and serving to propel the same. The electrical
circuit may be completed through the wheels of the car and the rails back to the
source of electrical energy.
The supplementary rail is divided into sections, and each section is subdivided
into elements suitably insulated from one another. The length of each clement is
by preference about one third the length of the car and its platforms; and the
distance between the two collectors carried by the car is about equal to the length
of one element. Each collector is distant about the length of one element from the
end of the car.
Each section or group of clements is provided beneath the surface of the road
with a commutating apparatus which serves to distribute the current to the
respective elements in proper order as hereinafter described. Leading from the
source of energy and laid beneath the surface of the road is a well-insulated main
conductor to which the distributers appertaining to the several sections are
respectively connected by means of branches. The clements of a section are
severally connected to the distributer by means of service conductors.
The arrangement of the distributer in relation to the two collectors carried by the
car is such that, as the car advances, the element next in advance o those for
the time being charged is thrown into electrical connection with the main conductor;
the rear one of the charged elements being immediately thereafter thrown out of
electrical connection with the main conductor.
This operation may be accomplished by making the distributer partake of the
nature of a circular switch-board having a centrally-pivoted arm in electrical
connection with the main conductor and working over a series of contact-pieces
insulated from one another and severally connected by means of the service
conductors to the elements. Corresponding to and connected with each contact-
piece is an electromagnet having an exciting coil of comparatively high resistance.
The pivoted arm is provided with an armature, and the various parts are so arranged
and electrically connected that the armature, carrying with it the arm, takes up a
position depending upon which of the electromagnets is or are excited; thereby
establishing electrical communication between the main conductor and the particular
element or elements corresponding with the contact-piece or -pieces with which the
distributer-arm is in contact.

page_text: It will be perceived that, as the car advances and brings its front collector into
contact with an element not hitherto charged, the said element becomes charged by
reason of its being electrically connected to the charged element or elements in
rear, and a current passes back-through the service conductor to the contact-piece
corresponding with the new element over which the car has arrived, and thence to
the corresponding electromagnet. This causes the pivoted arm of the distributer
to move forward, thereby breaking connection with the contact-piece corresponding
to the hindmost of the elements for the time being charged. The corresponding
electromagnet is thereby demagnetised, and the arm again moves forward, arriving
over the contact-piece corresponding to the element which had hitherto received its
charge (through the collectors) from the neighbouring element or elements. This
double operation is repeated for each element until the car arrives towards the end
of the section or group of elements.
In order to ensure the passage of the car from one section to the next and to
bring the distributer next in succession into operation, cach distributer is connected
to the nearest two elements of each of the adjoining sections.
Instead of employing in the distributer a separate electromagnet for each element,
I may use a smaller number not less than four. In such a case, the number of
elements in the section plus four must be some multiple of the number of magnets
in the distributer and I use two rows of contact-pieces insulated from each other.
The service conductors are led to one row and the terminals of the magnets are led
to the other row. The pivoted arm carries on each side a short-circuiting piece
insulated from the arm and so arranged that two pairs of contact-pieces, one pair in
advance and one in rear of the switch-bar or arm, are always connected; the pair
or pairs between being at the same time short-circuited by the arm itself. As the
armature makes a complete revolution during the movement of the car over as many
elements as there are magnets, the pivoted arm or switch-bar, instead of being rigidly
attached to the armature, is in this instance connected by means of gearing for
suitably reducing its circular movement.
Dated this 22nd day of Anvil 1800
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Effecting the Electric Propulsion of Tramcars and
Apparatus therefor.
I, JOHN GORDON, of Berlin, at present residing at 13, Nettleton Road, New
Cross, in the County of Kent, 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 :-
This invention relates to an improved method of and apparatus for transmitting
electrical energy from a fixed station where such energy is generated, transformed
or stored to a distant car, the propulsion of which is required to be effected by
means of an electric motor carried by the car.
For transmitting electrical energy under the above circumstances, it has been
customary to employ a continuous conductor arranged parallel with the tramway
and placed overhead, or below the car and slightly raised above the ground, or in
an underground conduit having a continuous slot open to the roadway. These
systems have the following disadvantages:The overhead conductor necessitates
the erection along the track of supporting poles and cross-arms, the unsightliness of
which, together with the danger from the overhead wire, have always provoked
great opposition to the construction of a tramway on this system. A continuous
conductor raised slightly above the ground is inadmissible in a thoroughfare.
Where the conductor is laid in an underground conduit, the open slot which is
necessary for establishing connection between the conductor and the motor carried

page_text: by the car is a source of danger to the public, especially to cyclists, and con-
siderable outlay is incurred in keeping the conduit free from water, snow and
mud.
To obviate or reduce the loss from leakage which occurs from a long conductor
not highly insulated, it has been proposed to use a main well-insulated conductor
and a supplementary working conductor divided into sections, and to place auto-
matic or hand-operated apparatus between the adjoining sections, so that, at any
one time, only that part of the working conductor in proximity to which the car
might be moving would be in electrical communication with the well-insulated con-
ductor. In this way, the length of conductor from which leakage could occur and
consequently the amount of leakage would be reduced.
Systems for street traffic have been proposed in which a main well-insulated con-
tinuous conductor is used in combination with an exposed supplementary conductor
divided into short lengths and arranged flush with the roadway; each length being
fairly well insulated from the earth and from the adjoining lengths. Apparatus,
which acts automatically to prevent any length, except when covered by a car,
being in connection with the main well-insulated conductor, is placed at or near
each length; thus reducing the leakage to a minimum and securing great safety as
regards the ordinary street traffic. The sections are, however, necessarily very
short, therefore a large number of sets of apparatus, with moving parts, would
require to be placed along the track, either under or near it, at very frequent
intervals.
Where a supplementary conductor composed of a series of short lengths is
employed, the current flowing through the circuit in which the motor for propelling
the car is comprised passes through the coils of the electromagnetic apparatus
used for putting the various short lengths of the supplementary conductor into
electrical connection with the main well-insulated conductor, and this current is
depended upon alone or in conjunction with a shunt current for exciting the
magnets. One disadvantage of this construction is that it is necessary to keep a
current sufficiently great to energize the electromagnets always flowing; such
current being shunted past the motor when not required for propulsion, as for
example when the car is at rest or going down hill. Another disadvantage is that
the said current is liable to be interrupted by the collector on the car momentarily
failing to make contact with one or another of the short lengths of the supple-
mentary conductor. In such a case, the electromagnetic apparatus would be
thrown out of action. To guard against a contingency of this kind, it has been
found necessary to provide subsidiary means, such as a battery carried by the car,
for re-establishing connection. A further disadvantage is that the number of turns
of wire in each magnet-coil of the electromagnetic apparatus must be such that,
with the minimum current, there are sufficient ampère turns to render the magnet.
operative consequently if, with the maximum current flowing, contact be
accidentally broken, the current thereupon induced would cause great sparking
where the break occurred.
The objects of my invention are to avoid or greatly reduce the disadvantages or
objections above mentioned, to effect increased economy in the cost of installation,
to afford greater efficiency and certainty in working, and to ensure safety, and a
minimum of disturbance to, the ordinary strect traffic.
In the accompanying diagrams,
Fig. 1 shews part of a tramway made according to my invention.
Fig. 2 represents on a larger scale one form of commutating or distributing
apparatus;
Fig. 3 being a corresponding view in a plane at right angles to the plane of
Fig. 2.
Fig. 4 is an enlarged view shewing the collectors on the car in contact with the
supplementary conductor.
In Fig. 5, cach collector is just over a space between two adjoining elements of
the supplementary conductor.

page_text: Fig. 4 shows the pivoted arm pertaining to the distributing apparatus or
commutating switch illustrated in Figs. 2 and 3 in contact with the contact-
picces which are in electrical communication with two of the elements of the
supplementary conductor covered by the car when in the position represented in
Fig. 4.
Figs. 5 and 6 are similar views, and correspond with Figs. 5 and 6
respectively.
Figs. 7 and 8 shew a modified form of the distributing apparatus illustrated in
Figs. 2 and 3.
Fig. 9 represents the distributing apparatus which I prefer to use.
Figs. 10, 11 and 12 serve to illustrate the various positions during the passage of
the car of the collectors relatively to the elements forming part of two adjoining
sections of the divided conductor, and the corresponding positions of the arms of
two sets of distributing apparatus.
A tramway laid according to my invention comprises rails of the ordinary
description whereon the wheels of the tramcar run, and a supplementary divided
and subdivided rail, bar or plate A laid in the track, preferably between the
ordinary rails, and serving to transmit electrical energy from the main conductor,
through collectors B and B attached to the frame of the tramear C, but insulated
from it, to an electric motor carried by and serving to propel the tramcar.
current flows thence through the frame and wheels of the tramcar to the rails,
which are electrically connected together and also to the return conductor leading
to the source of supply. The return conductor is connected to earth.
The
The supplementary rail or interrupted conductor A is divided into sections m
n, o, etc.; each section being subdivided into elements 1, 2, 3, etc. Twelve elements
are shewn by way of example in Fig. 1 as forming a section, but in practice each
section comprises from twenty to thirty of such elements. The length of each
element is by preference about one-third the length of the car and its platforms.
A space of about two or three inches is left between adjoining elements: this
space being filled with wood or asphalt; or with the material of which the road is
made, when such material is suitable; or with a mixture consisting of the material
of which the road is made and some suitable insulating substance. Sometimes the
upper surfaces of the elements, instead of forming a continuous plane surface, are
notched or serrated; the notches or serrations being filled with similar material to
that used for the spaces between the elements. The length of the collector B or B
must be greater than the length of any space a or notch or serration, in order that
contact between an element and the collector may never be broken. The distance
between the two collectors B and B is about equal to the length of one element;
the combined lengths of the two collectors and the space between them being
greater than the combined lengths of one element and two spaces, so that both
collectors can never stand entirely on one element. Each collector is placed about
the length of one element from the end of the car. The two collectors are united
electrically to each other and to one terminal of the motor carried by the car.
The other terminal of the motor is connected to earth through suitable regulating
devices and switches, and the framework and wheels of the car.
Each section or group of elements m or n or o, etc., is provided beneath the
surface of the road with a distributing apparatus, such as D (Fig. 2), which serves
to distribute the current to the respective elements 1, 2, 3, etc., in proper order, as
hereinafter described. Leading from the source of energy, and laid in a closed
conduit beneath the surface of the road, is a well-insulated main conductor E to
which the distributers D pertaining to the several sections m, n, o, etc., are
respectively connected by means of branches E. The elements 1, 2, 3, etc., of a
section mor n or o, etc., are severally connected to one of the distributers D by
means of service conductors e.
The service conductors or leads e, and usually also the main conductor E, are

page_text: placed in a closed conduit F, preferably made from gas piping, with T-pieces f
opposite each alternate space. The conduit F is also provided with cross-
conduits opposite cach distributer D. Each T-piece ƒ is closed with a tightly-
fitting insulating plug not shewn in the diagrams. Into each plug are driven two
rods of copper or other suitable metal, the inner end of each rod being so formed as
to enable good electrical connection to be conveniently made between it and one of
the two service conductors e which are connected to the two elements, the adjoining
ends of which are opposite the opening. The outer end of each metal rod
terminates in a stud shaped so that a short mechanically-strong conductor e¹ may
be firmly secured thereto; the other end of the short conductor e being secured to
the corresponding element, 1 or 2 or 3, etc. The short conductor or connecting
piece e is fairly well insulated in any convenient way, such as by surrounding it
with asphalt.
After the two service conductors e have been connected to the rods
in the plug, the latter is driven home and the joint between the plug and the
opening made as water-tight as possible. The short connecting conductors e¹ are
then secured to the outer ends of the rods and to the elements in such a way as to
ensure mechanical strength and good electrical contact.
If the copper or other metal rods be dispensed with, the ends of the service
conductors may be brought through holes in the plugs the holes being subsequently
stopped with cement.
The plugs are made to fit as nearly water-tight as possible, but where water
accumulates in the conduit, I provide either an off-fall into a neighbouring sewer
or a well into which the water may drain and whence it can be drawn off when
necessary.
The main conductor E, instead of being laid with the service conductors e in the
conduit F, may, if its insulation and the mechanical strength of its protective
covering be sufficient, be simply buried in the earth without further protection.
In some cases, I do not provide any special conductor, but draw the supply from
conductors which are being used for other purposes as well, such as for the supply
of electric light or power.
In every case, a branch is led from each distributer Ď
to the nearest point where connection can be made between it and the main conductor
leading from the source of supply.
The distributer D may often be conveniently placed under the pavement imme-
diately inside the curb-stone in a box G similar to the box known as a junction-box
in the Government Telegraph Service. The box may, if preferred, be buried near
the middle of the track or between the two tracks in a double tramway. In the
latter case, two distributers from the neighbouring sections of the two tracks may
be placed in one box. The receptacle for the distributer may sometimes, however,
be formed in the base of a street lamp-post.
Where the cross-conduit F¹ meets the conduit F, I place a junction-box, with a
movable lid, not shewn in the diagrams. The other end of the conduit F¹ is fitted
tightly to the distributer-box G.
The service-conductors e belonging to any section mor n or o, etc., are led from
the plugged openings along the conduit F to the junction-box, and thence
through the cross-conduit F¹ to the distributer D.
In the event of the main conductor E, the branch-conductor E, or any one of
the service-conductors e developing a fault or being accidentally damaged, the same
can be readily withdrawn and repaired or replaced; a minimum disturbance of the
roadway being involved.
The arrangement of the distributer D in relation to the two collectors B and B¹
is such that, as the car advances, the element 1 or 2 or 3, etc., next in advance of
those elements for the time being charged is thrown into electrical connection with
the main conductor E the rear one of the charged elements being immediately
thereafter thrown out of electrical connection with such conductor. This effect
must always take place, no matter whether any current be passing between the
elements and the motor carried by the car or not. That is, the car may be running

page_text: down hill without using any current or it may be at rest, but the elements covered
by the car, and these only, must always be charged.
This effect may be accomplished by making the distributer D partake of the
nature of a circular switch-board having a centrally-pivoted arm D¹ in electrical
connection with the branch E' from the main conductor E and working over a
series of contact-pieces 1, 2, 31, etc., insulated from one another and severally con-
nected by means of the service conductors e to the elements 1, 2, 3, etc. Corre-
sponding to and connected with each contact-piece is an electromagnet D³ having
an exciting coil d (Fig. 3) of comparatively high resistance. The electromagnets D
are arranged in a circle round a central electromagnet D. The cores of the
electromagnets are fixed to the iron base-plate D of the distributer D; such base-
plate acting, therefore, as a common yoke for all the electromagnets, so that their
free pole-pieces are at their upper ends and are marked 12, 23, 32, etc., in Fig. 2.
The pivoted arm D is provided with an armature D', which completes the
magnetic circuit between the upper or free pole of the central magnet and the
upper pole of one or poles of the surrounding magnets which for the time being
is or are excited. The various parts are so arranged and electrically connected
that the armature D, and consequently the arm D' to which it is attached, take up
a position depending upon which of the electromagnets D³ is or are excited, thereby
establishing electrical communication between the main conductor E (the current
passing through the branch conductor E', the arm D' and the contact-piece 11 or 2¹
or 3, etc., to the service conductor e) and the particular elements corresponding
with the contact-pieces with which the distributer-arm D¹ is in contact.
The upper
terminal of each coil d is connected to the corresponding contact-piece 11 or 2¹
or 3', etc. The lower terminals are united and connected to one terminal of the
central magnet-coil (Fig. 3); the other terminal of that coil being connected to
earth. The directions of winding are such that the upper pole of each magnet D³
has the opposite sign to the upper pole of the central magnet D'. It will thus be
seen there is a closed magnetic circuit formed, so that, if the central magnet D
and one or more of the surrounding magnets D3 be excited, the armature D'
will take up a position depending upon which of the surrounding magnets is or
are excited, as previously stated. The arm D', the outer end of which rubs over
the contact-pieces, is always charged.
The electromagnets D³, the contact-pieces and the elements are marked with
corresponding figures of reference. For instance, the element marked 6 is
connected to the contact-piece 6', which is connected to the electromagnet 62.
It will be perceived that as the car advances in the direction indicated by the
arrow y as, for example, from the position represented in Fig. 4 to that represented
in Fig. 5 and brings its front collector B' into contact with the element 8 which
was not hitherto charged, that element becomes charged, by reason of its being
electrically connected by means of collectors with the charged elements 6 and 7 in
rear, and a current passes through the service conductor e to the contact-piece 8¹,
thence to the electromagnet 82, and finally through the central magnet to earth, so
that now the three electromagnets 6, 7 and 82 are excited. This causes the
armature D² with the arm D¹ to move forward from the position shown in Fig. 4ª
to that shewn in Fig. 5, thereby breaking connection with the contact-piece 61;
the contact-piece 7' being then alone in electrical communication with the arm D¹,
so that no current passes from the main conductor E to the element 6, though that
element remains charged through being short-circuited with the element 7. T'he
electromagnet 62 is demagnetized when the collector B leaves the element 6, so that
then only the electromagnets 7 and 8' are excited. Consequently the armature D'
and arm D move forward from the position shewn in Fig. 54 to that shewn
in Fig. 64; thus making contact with contact-piece 8' as well as with the contact-
piece 71.
No further movement of the arm D₁ takes place until the car leaves the
position represented in Fig. 6 and the collector B¹ makes contact with the element 9
and breaks contact with the element 7, whereupon the armature D2 and arm D'

page_text: move forward twice, as previously described. A similar effect takes place in respect
of each element until the car arrives towards the end of the section or group of
elements.
In order to ensure the passage of the car from one section to the next and to
bring the distributer next in succession into operation, each distributer is connected
to the nearest two elements of each of the adjoining sections.
The contact-pieces m 121, m 11', o 2' and o l' are dummies and are isolated; the
terminals of the corresponding magnets m 122, m 112, o 22 and o 12 being led directly
to the elements 12 and 11 in section m and 2 and 1 in section o, as shewn in Fig. 2.
When, therefore, the arm D' is in contact with one or a pair of these dummy
contact-pieces, no current passes through it or them to any element in the track.
When the car arrives in such a position that the arm is over the dummy contact-
pieces, the distributer of the next section will have already been brought into
operation; the motor on the car receiving its current through its medium. It will
thus be seen that each distributer contains four more electromagnets than the
number of elements in the section which it operates.
Fig. 10 shews four elements of section n and three elements of section o with the
car in eleven different positions. Fig. 11 shows the cleven corresponding
positions of the pivoted contact-arm D and armature D2 of the distributer D
pertaining to section n. Fig. 12 shews the eleven corresponding positions of the
pivoted contact-arm and armature of the distributer pertaining to section o.
It will be seen that as the car advances the armature D2 and arm D¹ move round
into such positions that a current can pass from the main conductor E through such
contact-arm to the elements over which the car for the time being happens to be ;
and that, when the car arrives at the end of a section, the contact-arm of the
distributer pertaining to that section is left over a dummy or isolated contact-piece
until the next car in succession comes up and causes the arm to be again brought
into operation.
By this arrangement, if the motor carried by the car be provided with an
ordinary reversing switch, so that the current may be caused to pass through the
various parts of the motor in either direction at will, the car may at any moment be
made to move either forward or backward.
I
Instead of employing in the distributer a separate electromagnet for each element,
may use a smaller number not less than four. In such a case, the number of
elements in the section plus four must be some multiple of the number of magnets
in the distributer; and use two rows of contact-pieces insulated from each other.
The service conductors are led to one row and the terminals of the magnets are led
to the other row. The pivoted arm carries on each side a short-circuiting piece
insulated from such arm and so arranged that two pairs of contact-pieces, one pair
in advance and one in rear of the switch-bar or arm are always connected; the pair
or pairs between being at the same time short-circuited by the arm itself. As the
armature makes a complete revolution during the movement of the car over as
many elements as there are magnets, the pivoted arm or switch-bar, instead of being
rigidly attached to the armature, is in this instance connected by means of gearing
for suitably reducing its circular movement.
In Figs. 7 and 8, the central electromagnet D₁ is dispensed with. In this
construction, the terminals of the electromagnets D, after being brought together,
are led directly to earth. The current may, however, be led first through an inert
resistance. The base-plate D' is made of non-magnetic material, consequently each
of the electromagnets D has two free poles. The armature D8 is made of suitable
form to close or nearly close the magnetic circuit of the magnet or magnets which
for the time being is or are excited.
The
In these figures, the electromagnets, contact-pieces, contact-making arm and
armature are shewn by way of example in duplicate. The construction shewn in
Figs. 2 and 3 may likewise contain the corresponding parts in duplicate.
clectromagnets with corresponding numbers or letters of reference are connected in
parallel, and the corresponding contact-pieces are short-circuited. Under such

page_text: circumstances, the contact-making arm and armature make only half a revolution
while the car passes over the elements comprised in one section.
As the result of recent experiments (and having regard to the obligation imposed
upon me to disclose the best means with which I am acquainted for carrying out my
invention), I prefer to arrange the distributing apparatus in such a manner that the
centrally-pivoted revolving arm previously described may be dispensed with.
According to this modification, which will be readily understood on reference to
Fig. 9, I use electromagnets for actuating three contact-makers for each service-
. conductor.
1, 2, 3, etc., are a number of electromagnets of comparatively high resistance
arranged on a supporting plate D. When a current passes through any one of
these, its core is attracted upwards; and when such current ceases to flow, the core
falls down again under the influence of gravity. Instead of a core, the use of an
armature may in practice be found preferable."
Each core is provided with a weight 2 at its lower end. The upper end of
each core pertaining to the electromagnets 3 to 10 carries three contact-makers or
short-circuiting pieces k³, and insulated from one another. In the normal
position, contacts and are made and contact is broken. When a current
passes through the coil, the core k is pulled up contacts 3 and 5 being broken
and contact made, as in electromagnets 6 and 7. When such current ceases to
flow, the core falls automatically under the influence of gravity; contacts ³ and ³
being again made and contact broken, as in electromagnets 4 and 5, etc. In the
position of the parts as represented in Fig. 9, elements 6 and 7 are supposed to be
charged, so that electromagnets 6 and 7 are excited by currents passing through
the conductors and, through the respective magnet-coils and thence to earth.
These electromagnets being charged, the corresponding contacts are made so that
a current can pass from each branch conductor E by way of the corresponding
conductor, the contact-maker ³ pertaining to the electromagnet 4 or 5, the
corresponding conductor 2, the contact-maker & pertaining to the electromagnet 8
or 9, the corresponding conductor 0, the contact-maker k pertaining to the electro-
magnet 6 or 7, and the service-conductor e or e' to the element 6 or 7.
As the car advances so that the forward collector (B1) touches the element 8, a
current flows back through the service-conductored to the electromagnet 8 and thence
to earth. This current energizes the electromagnet 8 and causes its core k to be drawn
up so that its contact is made and its contacts k³ and are broken. No current
can then pass from the main conductor E through the service-conductor e, as the
contact-maker pertaining to the electromagnet 8 is out of operation. The
electromagnet 6 remains, however, excited, as the element 6 is still charged by
reason of its being short-circuited with the element 7 through the rear collector B.
No current can as yet pass from the main conductor through the service-conductor e³,
as the contact-maker ³ pertaining to the electromagnet 6 is still out of operation.
Immediately, however, the rear collector (B) leaves the element 6, the electro-
magnet 6 becomes demagnetized and its core k drops, whereby its contact-maker k³
is brought into operation; a current thereupon passing from the adjacent branch-
conductor E2 by way of the service-conductor to the element 8. That is, the
motor on the car then draws its supply of electrical energy through the service-
conductors and es. The operations above explained take place in respect of each
element in succession.
For the purposes of ensuring the passage of the car from one section to the next
and of guarding against an element being left charged after the car has passed,
four more electromagnets than there are elements in the section are employed,
thus following the example set in the apparatus shewn in Figs. 2, 3, 7 and 8.
Thus, the electromagnets 12 m and 11 m are respectively connected to the
elements 12 and 11 of section m, and the electromagnets 20 and 1o to the
elements 2 and 1 of section o. While the electromagnet 12 m or 11 m is excited,
no current can pass through the service-conductor e or e¹, and, while the
electromagnet 20 or 1o is excited, no current can pass through the service-

page_text: conductor e or e¹¹. The function which these extra electromagnets have to
perform is to cut off the supply through any distributer as soon as the car arrives
on the next section in advance; thus following the example set in the form of
distributer first described.
The effect of this construction will be readily understood after the explanation
previously given in reference to Figs. 1 and 2.
It will be observed that whereas each core k pertaining to the electro-
magnets 3 to 10 is furnished with three contact-makers ³, and, the core k of
cach of the electromagnets and 2 needs only two contact-makers and k, the
core of each of the electromagnets 11 and 12 only two contact-makers and ³,
the core of each of the electromagnets 11 m and 12 m only one contact-maker k³,
and the core k of each of the electromagnets 10 and 20 only one contact-maker **.
For the sake of symmetry, however, the core of each of the electromagnets 1, 2,
11 and 12 may be provided with a dummy contact-maker, and the core of each of
the electromagnets 11 m, 10 and 20 with two dummy contact-makers.
Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, I claim :-
12 m,
:-
1. The improved method of effecting the electric propulsion of tramcars,
substantially as herein described.
2. In effecting the electric propulsion of tramcars, the employment of means
arranged or operating substantially as herein described, and comprising a motor
and collectors carried by the car, a conductor composed of short lengths or elements
fairly well insulated from each other and from the earth, such elements being
grouped in sections of from twenty to thirty or thereabouts, a current-distributing
apparatus for each group of elements connected by means of service-conductors to
the several elements of the group and to the two adjacent elements of each of the
adjoining groups, and a main conductor or other suitable means for supplying current
to the several distributers; the operation of the parts being such that, as the car
advances, electrical communication is maintained between the main conductor and
the motor through the several elements in succession, during the passage of the car
over such elements.
3. In effecting the electric propulsion of tramcars over a tramway comprising
an interrupted conductor such as herein referred to, the employment of a current-
distributer or commutating switch operating to put the several elements of the
interrupted conductor comprised in a section-that is, a group of from twenty to
thirty such elements or thereabouts-successively into electrical communication
with the main conductor, and being also electrically connected to each of the
adjoining sections, so that, as a tramcar approaches the section, the distributer
pertaining thereto is placed in position to make electrical communication with the
several elements constituting that section, and ultimately to break such communi-
cation immediately the tramcar has passed.
4. In apparatus for effecting the electric propulsion of tramcars, the combination,
with a conductor composed of short lengths or elements fairly well insulated from
each other and from the earth and grouped in sections of from twenty to thirty or.
thereabouts, of current-distributers, one for each section or group of elements; such
distributers being arranged or operating substantially as described with reference
to the accompanying diagrams, Figs. 2 and 3 or Figs. 7 and 8, and for the purposes
herein set forth.
5. In apparatus for effecting the electric propulsion of tramcars, the combination,
with a conductor composed of short lengths or elements fairly well insulated from
each other and from the earth and grouped in sections of from twenty to thirty or
thereabouts, of current-distributers, one for each section or group of elements j
such distributers being arranged or operating substantially as described, with
reference to Fig. 9, and for the purposes herein set forth.
6. In effecting electric propulsion on tramways in which an interrupted con-
ductor is employed, the use of shunt currents only for the purpose of exciting
B

page_text: electro-magnets which operate to make and break electrical communication between
the source of electrical energy and the successive elements of the interrupted
conductor.
Dated this 21st day of February 1891.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Agent for the Applicant.