Improvements in Contact Making and Breaking Devices at Draw- bridges in the Overhead Circuit of Electric Tramways.
Year: 1896

page_text: Date of Application, 19th May, 1896-Accepted, 20th June, 1896
COMPLETE SPECIFICATION.
Improvements in Contact Making and Breaking Devices at Draw-
bridges in the Overhead Circuit of Electric Tramways.
I, JAMES DEVONSHIRE, Secretary of The British Thomson-Houstou, Limited,
of 38 Parliament Street, Westminster, London, do hereby declare the nature of
this invention (a communication from abroad by William B. Potter, Electrical
Engineer, of Schenectady, in the State of New York, United States of America,)
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 for its object to provide an improved circuit-breaker for
drawbridges, by means of which the circuit may be readily and automatically opened
and closed between the trolley wire extending lengthwise of the drawbridge and the
main trolley wire at the abutments of the bridge.
In carrying out this invention, a circuit breaking device is connected to each end
of the trolley wire extending lengthwise of the drawbridge, and when the
drawbridge is closed, the circuit breaking device at each end of the trolley running
lengthwise of the swing bridge is in contact with a similar abutting circuit-breaking
device connected with the main trolley wire at each abutment of the bridge. The
circuit breaking device is so constructed as to form a good contact with a similar
circuit-breaking device at one or both of the abutments, and when moved out of or
into contact therewith, to readily yield. The circuit-breaker comprises in its general
construction an inwardly yielding contact plate hinged at the outer end of a metallic
connecting piece, as hereinafter set forth and claimed.
In the accompanying drawings,
Fig. 1 is a diagrammatic plan view showing the application of the invention;
Fig. 2 is a perspective detail view of one of the circuit breakers constructed in
accordance with this invention;
Fig. 3 is a side view, in longitudinal section, of the circuit breaker shown
in Fig. 2.
The circuit-breaking device 1 may be constructed of a piece of metal of suitable
shape, such for example, as shown in Fig. 2, formed by the enlarged triangular
flauged portion 2, having the narrow rib 4 located at the top of the triangular
portion 2, and provided with projections 5 having screw threaded holes 6, by means
of which the circuit breaker may be secured by bolts or screws to the over-head
structure carrying the trolley wire. The extension 3 is formed with a channel 7
terminating at its inner end in a recess formed by a rearwardly projecting portion 8
of the rib 4, and adapted to hold the end of the trolley wire therein by means of
a set screw 9 mounted in and projecting through the projection 8. At the forward
end of the circuit-breaker is located a contact plate 10 hinged to trunnions 11
projecting from the sides of the triangular portion 2. The normal position of
the contact plate 10 is shown in Fig. 2, its forward movement being limited by
lateral projections 12 adjacent to its hinged portion, which abuts against stops 13
on the forward part of the portion 2 of the circuit-breaker. The contact plate 10
is held in this normal position by the pressure of spring arms 14 mounted
on the piece 2 and bearing against the rear of the contact plate 10, which
also permits the contact plate 10 to yield rearwardly when moving into or
out of contact with the adjacent contact plate mounted on the abutment of the
bridge.
In Fig. 1 is shown a swinging bridge 15 having extending lengthwise thereon a
trolley wire 16. Connected at each end of said wire 16 is the circuit breaker 1.

page_text: A circuit-breaker 17 similar in construction to the circuit-breaker 1 is located at
each abutment of the bridge, and is connected with the end of the main trolley wire 18
terminating at the abutment.
By means of this construction it will be seen that when the bridge is closed
the circuit is closed between the trolley wire 16 extending lengthwise of the
bridge and the main trolley wire 18, by means of the yielding contact plates
of the circuit-breakers, the abutting contact plates 1 and 17 bearing closely
together through the force of the spring acting on the rear of said contact plates.
The outer or front face of the contact plates is formed somewhat curved, as
shown, so that when the bridge swings away from or into position with the
abutments, the abutting contact plates may readily clear each other or move into
abutting position.
Provision is made to preserve the continuity of the main trolley circuit when
the bridge is open, as follows: A through feeder 19 extending preferably under
water, connects with the main trolley wire 18 so as to form an unbroken circuit, as
shown in Fig. 1. 20 indicates a ground wire extending preferably under water,
from the bridge to a generator at any suitable point connected with the main
trolley wire 18.
It will thus be seen that by means of this construction, when the bridge is open,
the main trolley circuit remains unbroken: and that when the bridge is closed, the
circuit across the bridge is completed by the contact plates held in close connection
with each other.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me
from abroad, I declare that what I claim is :
1. A circuit-breaker for drawbridges, consisting of a horizontal base plate, a
contact-plate hinged at its forward end and adapted to yield rearwardly in a vertical
plane, the outer face of the contact plate being curved from end to end horizontally,
and a spring holding the contact-plate in its forward position.
2. A circuit-breaker for drawbridges, consisting of a horizontal base plate
baving a rearward extension, with means for detachably securing the trolley wire
thereto, a contact-plate hinged at its forward end and movable rearwardly in
a vertical plane, and a spring connection permitting the contact-plate to yield
rearwardly.
3. The combination with a drawbridge having a trolley wire extending lengthwise
thereof, and a horizontal base-plate at each end of said trolley wire having hinged
thereto a contact-plate movable in a vertical plane, and a spring bearing against the
rear side of said contact-plate, of a similar contact-plate at each abutment of the
bridge abutting against the adjacent contact-plate on the bridge and connected to
one end of the wire in a trolley circuit.
4. The combination with a drawbridge having a trolley wire extending length-
wise thereof, and a circuit-breaker at each end of said trolley wire consisting of a
horizontal base-plate having hinged at one end thereof a contact plate movable in
a vertical plane, and a controlling spring in the rear of said contact-plate, of
a similar circuit-breaker at each abutment of the bridge abutting against the
adjacent contact-plate on the bridge and connected to one end of the wire in a
trolley circuit, said trolley circuit being unbroken when the bridge is open.
Dated this 19th day of May 1896.
J. C. CHAPMAN,
70 Chancery Lane, London, W.C., Chartered Patent Agent.