Improvements in the Means and Apparatus for Connecting Electrically Propelled Vehicles on Tram and Railways to Fixed Conductors.
Year: 1895

page_text: Date of Application, 23rd Dec., 1895
Complete Specification Left, 23rd Sept., 1995-Accepted, 23rd Jan., 1897
PROVISIONAL SPECIFICATION.
Improvements in the Means and Apparatus for Connecting
Electrically Propelled Vehicles on Tram and Railways to
Fixed Conductors.
We DAVID URQUHART of 17 Victoria Street Westminster and FRANK
WYNNE of 13, Ashley Gardens 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 ears in
which the electric energy required is generated at a fixed point or points and
conducted to the moving car by means of fixed insulated conductors and a series
of suitably insulated short contact surfaces exposed in the roadway (hereinafter
called road contacts) such road contacts being automatically connected by some
switch device to the electrical main when the car is over' or nearly over them and
automatically disconnected from such main when the car has passed them the car
being provided with a brush or collector which rubs on the road contacts thus
connecting the driving motor to the electric mains.
Usually an electromagnet is employed to actuate the switch which connects the
road contact over which the car may be to the electric main, this electro-magnet
when energized attracting an armature or keeper which by its motion closes the
switch against the force of gravity or against a spring or both, so that, on the
electro-magnet ceasing to pull, the switch will automatically open and disconnect
the road contact from the electric main.
In all cases where the magnet which actuates the switch has a winding carrying
the main current it may happen under certain conditions that there will be sufficient
leakage from the road contact just left to the road contact ahead to keep the
magnet armature attracted thus preventing the switch from automatically opening.
To obviate this we sometimes place a conducting bar or plate preferably sunk
in the center of the gap between consecutive road contacts, and connect it to the
main through the switch of a trailing road contact, a second or pull down magnet
being inserted in the connecting lead;.any leakage current will then pass principally
round this pull down magnet and ensure the opening of the switch.
The inserted har between two consecutive road contacts may be formed with a
side projection so placed that the fain brush having a side extension shall touch it
after leaving the trailing contact thus ensuring the passage of a momentary current.
through the pull down magnet.
Under certain conditions there may also be sufficient leakage from the road
contacts to earth to keep the switch with main current winding closed; this we
obviate by placing a metal bar on each side of the road contact, these bars being
connected to the main when the switch is closed but through the winding of the
pull down magnet instead of through the winding of the switch magnet. The
leakage current will then help to open the switch.
Instead of two bars we sometimes use a curved plate or channel round the road
contact but insulated from it so as to cut off all leakage from it, and we sometimes
make this part of a channel in which to carry the main conductor.
We have described our invention as applied to cars carrying a relatively short
collecting brush or brushes rubbing on a relatively long road contact or a series of.
contacts electrically connected, but our invention can be equally applied to cars

page_text: provided with a long contact bar or brush rubbing on short studs or plates placed
in the roadway.
Dated this Twenty-first day of December 1895
DAVID URQUHART.
FRANK WYNNE.
Improvements in the Means and Apparatus for Connecting
Electrically Propelled Vehicles on Tram and Railways to
Fixed Conductors.
We, DAVID URQUHART, of 17, Victoria Street, Westminster, and FRANK
WYNNE, of 13 Ashley Gardens, 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 :-
Our invention has reference to electric tramways and railways in which the
electric energy required is generated at a fixed point or points and conducted to
the motor on the vehicle to be electrically propelled (hereinafter called the car) by
means of fixed insulated conductors and a series of suitably insulated short contact
surfaces exposed in the roadway and hereinafter called road contacts, such road
contacts being automatically connected by some suitable switch device to the
electrical main when the car is over or nearly over them, and automatically
disconnected from such main when the vehicle has passed them, the car being
provided with a brush or collector which rubs on the road contacts thus connecting
the driving motor to the electric main.
Usually an electro-magnet is employed to actuate the switch which is to connect
the road contact over which the vehicle may for the time being be situated, to the
electric main, this electro-magnet, when energised, attracting an armature or
keeper which, by its motion, closes the switch against the force of gravity, or
against a spring, or both, so that on the electro magnet ceasing to pull, the switch
will automatically open and disconnect the road contact from the electric main as
well understood.
In all cases where the electro-magnet which actuates the switch has a winding
carrying the main current, it may happen under certain conditions that there will
be sufficient leakage from the road contact just left to the road contact ahead, to
keep the magnet armature attracted, thus preventing the switch from automatically
opening; and this invention has for object to obviate this disadvantage.
For this purpose according to one arrangement we place a conducting bar or
plate (bereinafter called a guard plate), preferably sunk in the roadway, in the
centre of the gap between consecutive road contacts, and connect it to the main
conductor through the switch of a trailing road contact, a second or pull down
electro-magnet being inserted in the conpecting lead so that any leakage current
that may take place will then pass principally round this pull down electro-magnet
and ensure the opening of the switch.
Fig. 1 of the accompanying drawings shows diagrammatically, one arrangement
of this kind applied in connection with means or apparatus of the kind berein
referred to for electrically connecting a motor on a car to an insulated main
conductor.
1,1 are insulated road contacts in the form of short bars arranged longitudinally
of the roadway and each adapted to be placed in electrical connection, at the
proper time, with an insulated main conductor 2 through the winding 3 of an
electro-magnet 4 and a conductor 5 by a spring or gravity switch lever 6 which
forms au armature to the electro-magnet and carries an insulated contact piece 6°

page_text: which bears, when the switch lever is attracted, against contacts 3º and 5ª on the
normally free ends of the winding 3 and conductor 5 respectively, and which
automatically moves away from such contacts when the circuit of the electro-
magnet is broken, as well understood.
7,7 are conducting guard-plates each placed in the gap between the ends of
successive road contacts 1, preferably sunk in the roadway below the level thereof,.
and connected by a conductor 8 to the main conductor 2 through the switch of the
adjacent trailing road contact, that is to say the switch of the road contact to
the rear of it. In the example shown, the conductor 8 is connected to the-
conductor 3 of the trailing road contact at a point between the corresponding
electro-magnet 3-4 and the contact 3*; and included in it is an electro-
magnet 9 arranged below the switch lever 6 which forms an armature to it..
With this arrangement, a leakage current passing round the winding of the
electro-magnet 9 will energise this magnet and cause it to pull down the switch
lever 6 and break the circuit between the corresponding road-contact and the-
main conductor 2.
Under certain conditions there may also be sufficient leakage from the road.
contacts 1 to earth to keep the switch with main current winding 3 closed.
This we obviate by placing a metal bar or rail 11 on each side of each road
contact, as shown in full lines in Fig. 2, these bars being connected to the
main conductor 2, when the corresponding switch is closed, through the winding
of the pull down magnet 9 as in Fig. 1, and not through the winding of the
switch magnet.
Instead of two bars we sometimes place a curved plate or channelled bar
round each road contact but insulated therefrom so as to cut off leakage from
it. Such a curved plate or channelled bar, which would enclose the road contact.
except on its upper surface, is indicated by the full and dotted lines 11, 11° in
Fig. 2, the insulating material in which the road contact 1 is placed being
indicated at 12. The channelled bars 11, 11ª may be used to carry the
insulated main conductor 2.
In each case the bar or bars or channel, as the case may be, will by the
arrangement described, be at about the same potential as the corresponding
road contact so that no leakage current can pass through or over the insulation 12
and all leakage current must take place from the bars 7 or 11 through the
leads 8 and switch contact 3, and will thus help to open the switch.
Each bar 7 placed between two consecutive road contacts, as in Fig. 1, may
be formed with a side projection 7ª so placed (as shown for example in side
elevation and plan in Figs. 3 and 4 respectively) that the car contact brush 10.
which in this case will be provided with a short lateral extension, shall touch
it after leaving the road contact to the rear of it, thus ensuring the passage of
a momentary current through the pull down magnet 9 corresponding to euch
road contact and the disconnection of such road contact from the main conductor.
Such additional forward side projection 7 might obviously be combined with
guard rails, or a channel bar, airanged at the side of or surrounding the next
rearward road contact, as shown for example in plan in Fig. 5, where it is shown.
as connected to a channelled bar surrounding the rearward road contact.
We have described our invention as applied to cars carrying a relatively
short collecting brush or brushes rubbing on relatively long road contacts, or
it may be groups of road contacts, the contacts in each group being electrically
connected together, but our invention can be equally applied to cars provided
with a long contact bar or brush rubbing on short studs or plates placed in the
roadway.
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:
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page_text: electrically propelled vehicles, the combination with each of the road contacts of a
conducting guard-plate placed between it and the preceding road contact, or of
conducting guard rails placed at the side of the road contact, or of a guard channel
surrounding the said road contact, such guard plate, guard rails, or guard channel
being connected to the main conductor of electricity through the same switch
as the road contact itself but not through the winding of the switch magnet.
2. In apparatus of the kind herein referred to for supplying electricity to
electrically propelled vehicles, the combination with the guard-plate, guard-rails or
guard channel, referred to in the preceding claim, of a pull down electro magnet
inserted in the conductor connecting the said guard plate, guard rails or guard
channel to the switch and so arranged relatively to the moving part of the switch
that when energized it shall assist in opening the switch.
3. The combination with the switches for electrically connecting road contacts
with a main conductor for supplying electricity to electrically propelled vehicles,
of supplementary or pull down electro-magnets and connections constructed,
arranged and operating substantially as herein before described with reference
respectively to and shown in Fig. 1; in Fig. 2; in Figs. 3 and 4; and in Fig. 5 of
The drs need
Dated this 23rd day of September 1896.
For the Applicants,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.