Improvements in the Means or Apparatus Used for Connecting Electrically Propelled Vehicles on Tramways and Railways to Fixed Conductors.
Year: 1896

page_text: Date of Application, 25th Jan., 1896
Complete Specification Left, 26th Oct., 1896-Accepted, 23rd Jan., 1897
PROVISIONAL SPECIFICATION.
Improvements in the Means or Apparatus Used for Connecting
Electrically Propelled Vehicles on Tramways and Railways to
Fixed Conductors.
DAVID URQUHART of 17 Victoria Street and FRANK WYNNE of 13 Ashley
Gardens in the City of Westminster Civil Engineers do hereby declare the nature
of this invention to be as follows:-
Our invention has reference to electrically propelled tram and railway cars and
to locomotives where the electrical energy required is generated at a fixed point or
points and conducted to the moving vehicle by means of fixed conductors (which
may consist of two suitably insulated conductors or of one insulated and one
uninsulated conductor, in which case the rails may be or form part of such
uninsulated conductor) and a series of suitably insulated short contact surfaces
exposed in the roadway (hereinafter called road contacts, such road contacts being
automatically connected by a switch device to the insulated electric main' when
the car covers or nearly covers them and automatically disconnected from such
main when the car has passed them, the car being provided with a metallic brush
or brushes, or with collecting wheels or other such device, (hereinafter called the
main brush) which rub on the road contacts thus connecting the driving motor of
the car (hereinafter called the motor) to the electric mains; when the rails are
connected to or constitute one of the mains, the running wheels of the car may be
used as the collector or contact between the motor and that main, and when
referring to such an uninsulated main we shall hereinafter use the expression
"earth."
In carrying out our invention we generally prefer to make the road contacts
about half the length of the car, so that the car and its extensions will about cover
two road contacts and the gap which separates them.
To each road contact we connect one coating of an electric condenser of suitable
capacity, the other coating of the condenser being connected to earth. This
condenser we place in any suitable box or receptacle in the roadway.
We further arrange an electro-magnet of suitable construction, in connection
with the switch for connecting the road contact to the insulated main, so that on
this magnet being energized by an electric current, the motion of the magnet
armature will close the switch, and on the electro-magnet ceasing to attract its
armature, the switch will open either by gravity or through the action of a spring
or both.
This electro-magnet we insert either between the condenser and the road contact,
or between the condenser and earth, so that any current flowing in and out of the
condenser must pass round its windings and energize it.
We also place on the car an apparatus for producing alternating currents of suitable
frequency, such as an alternating current dynamo driven either by the motor or
from a battery on the car or a Ruhmkoff coil with a make and break arrangement
worked from the main motor current or from a battery.
This apparatus. whatever form it may take, we hereinafter call the alternator.
We connect one terminal of the alternator to the main brush and the other

page_text: terminal to earth. We sometimes place a choking coil in the connection between
the main brush and the motor terminal.
When the main brush rests on a road contact there will then be two paths for
the alternating current, one to the main brush, thence through the choking coil
and motor to earth and back to the alternator, the other from the main brush to
the road contact thence to the condenser and from the condenser to earth, and
back to the alternator, passing round the windings of the electro-magnet. If the
choking coil is suitably constructed nearly the whole of the alternator current will
pass around this second path, and will thus energize the electro-magnet and actuate
the switch.
On the switch being closed, the alternator current may pass to earth through
the main and the generator at the generating station. To prevent this we
sometimes place a choking coil in the connection between the switch and the
main.
We sometimes combine this method of actuating the switch with a holding up
device consisting of a separate winding round the electro-magnet through which
the main current will flow or of a separate electro-magnet energized by the main
current and so arranged as to hold up the armature and keep the switch closed so
long as current is passing from the main to that particular road contact, that is, so
long as the main brush is on that road contact.
We sometimes include in the alternator connections on the car a high resistance
having little or no induction so as to prevent any of the main continuous current
from being short circulated through the alternator, or we insert a condenser in 'the
alternator connection on the car for the same purpose.
We sometimes modify this arrangement by placing a second brush on the car,
about one road contact length in advance of the main brush and connecting the
alternator to this advance or switch brush instead of to the main brush. In this
case the switch connections are so arranged that the road contact which is by its
. action connected to the main is not the road contact to which the condenser coating
. is connected but the road contact in rear of that one is so connected. Thus so long
as the switch brush bears on one road contact, the road contact behind and on
which the main brush will then be bearing, will be the one connected to the
.main.
A second method which we employ for actuating the switch is to place a
condenser at each gap between the consecutive road contacts, the coatings of the
condenser being connected respectively to the two bars, the electro-magnet being
as before inserted in one of these connections.
In this case we place two brushes on the car, the one being the main brush
.connected both to the alternator and to the motor and the other or switch brush
. being connected to the alternator only.
This switch brush we place a road contact length or nearly a road contact
.length from the main brush, in advance of it if the switch electro-magnet is in the
connection from the trailing road contact to the condenser, and in the rear of it if
the switch electro-magnet is in the connection from the front road contact to the
. condenser. So long as the two brushes rub on different bars there will be a
. completed condenser circuit through the alternator and condenser coatings and the
switch will be actuated.
In connection with this arrangement we prefer to use a holding up device as
described above, as otherwise the switch will open whenever the two brushes are
on the same bar and also when the main brush is bridging the gap between the
road contacts, unless a choking coil is inserted to prevent this.
We also prefer in this case to make the road contacts only about one third the
.length of the car as at the moment that the motor bridges a gap three road
contacts will be electrically connected to the main. The appropriate length of
the road contacts will depend on the distance which separates the switch brush
sand-the main brush.
As the alternator is short circuited whenever the two brushes make contact with

page_text: the same road contact we sometimes place a choking coil in the alternator circuit
on the car whenever the two brushes are placed less than a road contact length
apart.
This choking coil must be designed to allow the current required to energize the
switch magnet to pass, but to choke back any larger current.
We sometimes modify this arrangement by using two alternators on the car, so
driven as to be always in step and we use four brushes on the car none of which is
long enough to bridge the gap between the road contacts.
Taking these brushes in their order the forward one or No. 1 is a switch brush.
connected to one terminal of No. 1 alternator.
No. 2 brush acts both as a switch and a main brush being connected to one
terminal of No. 2 alternator and to the motor terminal a choking coil being
inserted in the latter connection.
No. 3 brush is a switch brush being connected to the other terminal of
No. 1 alternator. No. 4 brush is both a switch and a main brush being connected
both to the other terminal of alternator No. 2, and to the motor. The distance
between these brushes is such with reference to the length of the road contacts,
that the circuit of alternator No. 1 is completed to a forward condenser before the
circuit of alternator No. 2 is broken by the brush No. 4 leaving the rearward
contact. There are thus at times three road contacts having brushes bearing on
them and two of these are then connected to the main.
A further modification which we sometimes use consists in making the condenser
at one gap energize the switch at the road contact behind the two which are
connected to that condenser, this being effected by taking a separate insulated lead
back from each condenser to the switch in the road behind it. In this case the
four brushes described above become all of them switch brushes, not being
connected to the motor in any way and a fifth brush, which is the main brush is
placed on the car behind these four switch brushes.
We have described the principal methods we employ for actuating the road but
these methods may be modified in various ways and where we have described the
connections with reference to the motion of the car in one direction it is evident
that the connections will either equally apply for motion of the car in the other
direction or that by the introduction of switches on the car the connections can be
altered to suit motion in the other direction.
We have also described these methods as applied to cars using the rails as part
of the return circuit but they are equally applicable in cases where the return
connection is also made by means of road contacts, and in this case the electro-
magnet may be made to actuate both switches at the same time.
Dated this Twenty-fifth day of January 1896
DAVID URQUHART.
FRANK WYNNE.
COMPLETE SPECIFICATION.
Improvements in the Means or Apparatus Used for Connecting
Electrically Propelled Vehicles on Tramways and Railways to
Fixed Conductors.
We, DAVID URQUHART, of 17 Victoria Street, and FRANK WYNNE, of
13 Ashley Gardens, both in the City of Westminster, Civil Engineers, 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 has reference to improvements in that kind of means or apparatus

page_text: for electrically propelling tramway and railway vehicles including locomotives
(hereinafter called cars) in which the electrical energy required is generated at a
fixed point or points and conducted to the moving vehicle by means of fixed main
conductors, and a series of suitably insulated short contact surfaces (hereinafter
called road contacts) that are exposed in the roadway and are automatically
connected by switch devices to one of the main conductors when the car covers or
nearly covers them and are automatically disconnected from such main conductor
when the car has passed them, the car being provided with a metallic or other
conducting brush or brushes, or with collecting wheels or other suitable device
(hereinafter called the main brush) arranged to rub on the road contacts and thus
connect the driving motor of the car (hereinafter called the motor) to the said
main conductor. Both main conductors may be insulated or only that one to
which the road contacts are temporarily connected, the other being uninsulated.
In the latter case, the rails on which the vehicle runs may be or form part of such
uninsulated main conductor. When the rails are thus connected to or constitute
one of the main conductors, the running wheels of the car may be used as the
collector or contact between the motor and that main conductor, and when
referring to such an uninsulated main conductor we shall hereinafter use the
expression "earth."
In carrying out our invention we generally prefer to make the road contacts
about half the length of the car, so that the car and its extensions will about cover
two road contacts and the gap which separates them.
An object of the invention is to enable each of the said switches to be closed
electrically without the winding of the electro-magnet that operates the switch
lever being at any time placed in connection with the main conductor and con-
sequently traversed by the main current passing to the motor, so that there shall
be no liability of the switch being kept closed after the vehicle has passed the
switch by leakage of electricity from the main conductor to a road contact through
the winding of the corresponding switch magnet.
For this purpose to each road contact (there is connected one coating of an
electric condenser the other coating of which is connected to earth. This
condenser, of suitable capacity, may be placed in a suitable box or receptacle in
the roadway. In connection with the switch for connecting the road contact to
the insulated main conductor there is provided an electro-magnet so constructed
and arranged that when energized by an electric current, it will operate the magnet
armature and close the switch, and on the electro-magnet ceasing to attract its arma-
ture, the switch will open either by gravity, or through the action of a spring,
or both.
Or the opening of the switch may be assisted by another electro-magnet, as
described in the Specification of another Application for Letters Patent filed by
us No. 24578 of 1895. This electro-magnet, which is preferably made with a
laminated iron core, is inserted either between the condenser and the road contact,
or between the condenser and earth, so that any current flowing in and out of the
condenser must pass round its winding and energize it. On the car to be propelled
is an apparatus for producing alternating or intermittent currents of suitable
frequency. This apparatus may be an alternating current dynamo driven either
by the motor, or from a battery on the car; or it may be a Ruhmkoff coil
provided with a make and break arrangement and worked from the main motor
circuit, or from a battery so as to produce an intermittent current as well
understood. This apparatus, whatever form it may take, is hereinafter called
the alternator. One terminal of the alternator is connected to the main brush
and the other terminal to earth. Sometimes a choking coil is placed in the
connection between the main brush and the motor for a purpose hereinafter
mentioned.
Fig. 1 of the accompanying drawings is a diagrammatic view showing one
arrangement of current supply apparatus according to this invention.
1,1 are the road contacts in the form of short rails arranged longitudinally
in the roadway and in connection with each of which there is provided an

page_text: electro-magnetically operated switch for connecting the road contact to the
insulated main conductor 2 of electricity. Each switch comprises an electro-
magnet the laminated core 3 of which has one end of its winding 4 connected
to the corresponding road contact and its other end to one coating 5 of a con-
denser the other coating 5 of which is connected to earth E; and a switch
lever 6 adapted to be attracted or moved into its closed position against the
force of gravity, or of a spring, or of both, by the electro-magnet 3-4 when
the same is energised and to then electrically connect together insulated
contacts 7, 8 that are in connection respectively with two conductors 7, 8,
connected the one with a road contact and the other with the main conductor.
9 is the car to be propelled; 10 the car motor having its terminals connected the
one with a main brush 11 carried by the car, and the other with earth E¹ through
the metal frame of the car, car wheels and rails on which the car travels; 12 is an
alternator arranged on the car and having one of its terminals connected to the
main brush 11 and the other to earth E'; and 13 is a choking coil placed in the
connection 13 between the main brush and the car motor. The main brush 11 is
made sufficiently long to bridge each gap 1 between adjacent road contacts 1.
The alternator, which is of the kind hereinbefore described, may have for example
a frequency of say about 1000 alternations per second. With this frequency each
condenser 5, 5ª which may be constructed of tin foil with paraffined paper insula-
tion, may have a capacity of one microfarad. The choking coil 13 may be of
ordinary construction and wound to suit the frequency of the alternator.
As will be seen the arrangement is such that when the main brush 11 rests on a
road contact 1 there will be two paths for the alternating current produced by the
alternator 12, viz. one to the main brush 11 thence through the choking coil 13 and
motor 10 to earth E' and back to the other terminal of the alternator; the other
from the main brush to the road contact, thence to the condenser 5, 5 and from
the condenser to earth and back to the alternator, passing in its course round the
winding 4 of the electro magnet 3-4 which, as hereinbefore stated, may be placed
between the condenser and earth instead of between the condenser aud the road
contact. If the choking coil 13 is suitably wound, nearly the whole of the
alternator current will traverse this second path and will thus energize the electro-
magnet 3-4 and actuate the switch lever 6 in a direction to connect the
corresponding road contact 1 with the main conductor 2, through the leads 7
and 8.
To prevent or check the alternator current passing to earth through the main
conductor 2 and the generator 15 at the generating station when any one of the
switches is closed, a choking coil 16 may be placed in the connection 7, 8 between
each switch and the main conductor.
The means hereinbefore described of actuating the switch of each road contact
may in some cases have combined therewith a holding-up device consisting either
of a separate winding 7b as shown in Fig. 2, wound around the electro-magnet.
core 3 and through which the main current will flow when the switch is closed, or
of a separate electro-magnet comprising a winding 7° and core 3" as shown in
Fig. 3, the core 3 or 3ª in each case being energized by the main current and so
arranged, as shown, as to hold up the armature or switch lever 6 and keep the
switch closed so long as current is passing from the main conductor to the
corresponding road contact, that is to say, so long as the main brush 11' is on that
road contact.
We sometimes include in the alternator connection 12" on the car Figs. 1, 2
and 3, a high resistance having little or no induction, such for example as a series
of incandescent electric lamps, so as to prevent any of the main continuous current.
that is passing to the brush 11 from being short circuited through the alternator 12;
or a condenser 17 may be inserted in the said alternator connection for a like
purpose.
Fig. 4 is a diagrammatic view showing a modified arrangement in which a second
brush 14 on the car is placed about one road-contact length in advance of the main.

page_text: brush 11, and the alternator 12 is connected to this advanced or switch-brush
instead of to the main brush. In this case the switch connections 7, 8 and leads 7
and 8 are so arranged that the road contact which is by the action of the switch
connected to the main conductor, is not the road contact 1 to which the condenser
coating 5 of the switch is connected but the road contact 1 in rear of such road
contact 1. Thus, so long as the switch brush 14 bears on one road-contact, the
road-contact behind and on which the main brush 11 will then be bearing, will be
the one connected to the main conductor 2. The leads 7 and 8 may include a
winding such as 7 in Figs. 2 and 3, to be traversed by the main current and hold
the switch lever 6 in its closed position so long as the main brush 11 is on the
corresponding road contact. This winding may be on the core 3 of the switch
magnet as in Fig. 2, or as shown in Fig. 3, on a separate core.
Fig. 5 shows diagrammatically another arrangement in which for actuating the
switch, a condenser is placed at each gap between the consecutive road-contacts,
the coatings 5, 5 of the condenser being connected respectively to the two adjacent
road contacts 1, the electro-magnet 3-4 for operating the switch lever 6 being, as
before, inserted in one or other of the two connections. In this case two brushes
are placed on the car, one viz. 11, being the main brush connected both to the
alternator 12 and to the car motor 10, and the other or switch-brush 14 being
connected to the alternator only. This switch brush 14 is placed a road-contact
length, or nearly a road-contact length, from the main brush 11, and in advance of
it, if the trailing road contact 1" of the pair is the one connected to the main
conductor by the operation of the switch, as in the arrangement shown in Fig. 5,
and in the rear of it if the leading road contact of the pair be the one that is
connected to the main conductor by the switch, as shown in Fig. 5. So long as
the two brushes 11, 14 rub on different bars there will be a completed condenser
circuit through the alternator and condenser coatings and the switch will be
actuated. In these two arrangements we prefer, as shown, to use a holding-up
device such as the electro-magnet 3, 7, for the switch lever 6, as otherwise the
switch will open whenever the two brushes are on the same road contact, and also
when the main brush is bridging a gap 1 between adjacent road-contacts, unless a
choking coil 13 is inserted between the main brush and alternator, as shown in
Fig. 54, to prevent this action taking place.
In this arrangement it is advantageous to make the road-contacts 1 only about
one third the length of the car, as, at the moment that the main brush 11
bridges a gap 1, three road-contacts will be electrically connected to the main
conductor 2. The appropriate length of the road-contacts will depend on the
distance which separates the switch-brush and the main brush. When the distance
spart of the brushes is less than the length of each road-contact, a choking coil 13
is placed in the alternator circuit on the ear to prevent the alternator being short
circuited when the two brushes make connection with the same road-contact. This
choking coil must be so designed as to allow the current required to energize the
switch magnet to pass, but to choke back any larger current.
When a holding-up electro-magnet 3° 7 is used in this arrangement, the switch
brush 14 may be placed sufficiently far from the main brush to prevent them from
ever being simultaneously upon the same road contact. In this case the choking
coil 13 can be dispensed with.
We prefer to so construct the alternator that it will yield a constant current,
that is to say, so that the current produced will not materially. increase with
reduction of the resistance of the condenser circuit.
Fig. 6 shows diagrammatically a modified arrangement in which there are
provided on the car two alternators 12, 124 so driven as to be always in step, and
four brushes 11, 11" and 14, 14" none of which is long enough to bridge the
gaps 1 between the adjacent road contacts. Taking these brushes in their order,
the first or forward one 14 is a switch brush connected to one terminal of the
alternator 12;. the second brush 11 acts both as a switch brush and a main brush,
being connected to one terminal of the alternator 12" and to one terminal of the

page_text: car motor 10, a choking coil 13 being inserted in the latter connection. The third
brush 14 is a switch brusb, being connected to the second terminal of the
alternator 12, and the fourth brush 11 is both a switch and a main brush being
connected both to the second terminal of the alternator 124 and to the motor 10.
The distance between these brushes is such, relatively to the length of the road
contacts, that the circuit of the alternator 12 is completed to a forward con-
denser 5, 5 through a forward road contact 1, before the circuit of alternator 12
is broken by the fourth brush 11 leaving the rearward road contact 1. There
are thus at times three road contacts viz. 1, 1" 1° having brushes bearing on them,
and two of these viz. 1° and 1b are connected to the main conductor 2.
Fig. 7 shows a modification of the last described arrangement wherein the first
and second brushes 14 and 11 are both switch and main brushes, and the brushes 14"
and 11 switch brushes only. With this, arrangement the choking coil 13 (Fig. 6)
can be dispensed with, the construction and operation in other respects being
similar to the arrangement shown in Fig. 6.
Fig. 8 shows a modification of the two last described arrangements wherein the
condenser 5 5 at each gap 1 is used to effect the operation of the switch at the
road contact 1b behind the two road contacts 1, 1" which are connected to that
condenser, this being effected by taking a separate insulated lead 7° back from each
condenser to the switch in the road box behind. In this case the four brushes 14, 11
14 and 11 all become switch brushes, not being connected to the car motor in any
way, and a fifth brush 11, which is the main brush, is placed on the car behind the
four switch brushes.
We have described the principal methods we employ for actuating the road
switches, but these methods may be modified in various ways, and where we have
described the connections with reference to the motion of the car in one direction, -
it is evident that the connections will either equally apply for motion of the car
in the other direction, or that by the introduction of switches on the car, the
connections can, as well understood, be altered to suit motion in the other
direction.
We have also described our methods as applied to cars using the rails as part
of the return circuit, but they are equally applicable in cases where the return
connection is made by means of additional road contacts in which case the
electro-magnet corresponding to each main road contact may be made to simul-
taneously actuate the switches of both the main and return road contacts.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. In apparatus of the kind herein referred to for connecting electrically
propelled vehicles on tramways and railways to fixed conductors, operating the
switches for successively connecting the road contacts to the main conductor by
meaus of an alternating or intermittent current acting in conjunction with
condensers in connection with the road contacts, and with the switch operating
electro-magnets.
2. For connecting electrically propelled vehicles on tramways and railways to
fixed conductors, means or apparatus constructed, arranged and operating sub-
stantially as herein before described with reference to the several examples
illustrated in the drawings annexed.