Improvements in Indicators or Repeaters for Night or Light Signals.
Year: 1894

page_text: Date of Application, 10th Nov., 1894-Accepted, 5th Jan., 1895
COMPLEIN SI MOITICATION.
Improvements in Indicators or Repeaters for Night or Light Signals.
A communication from abroad by Louis F. JOHNSON, of Poughkeepsie,
State of New York, United States of America.
I, JOHN PATRICK O'DONNELL of 70 and 71, Palace Chambers, Bridge Street,
Westminster, in the County of Middlesex, Civil Engineer and Patent Agent, 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:—
Various so-called thermostatic devices, wherein a change of temperature is
caused to open or to close an electric circuit, have been used heretofore for different
specific purposes. My present invention relates in general to devices of this kind
and its special object is to provide improved means whereby the condition of a
railway switch or signal lamp may be reliably indicated at the signal box. The
invention consists in the combination and arrangement of parts hereinafter
described whereby a circuit which is normally closed is broken by the extinguish
ment of a light and at the same time another path is offered for the current ;
under this arrangement the breaking of the circuit either by the extinguishment
of the light or from any other cause made to give both a visual and an audible
alarm, whereby the possibilty of accidents is reduced to a minimum.
In the accompanying drawings:
Figure 1 is a view showing in elevation the indicator mechanism which is placed
in the signal box, the electric connections and the switch lamp and circuit
closing device controlled thereby, the door of the casing about the indicator
devices being represented as open and broken away, and the front plate of the
casing within the door being also represented as partly broken away to show the
devices behind it.
Figure 2 is a view showing the indicator in perspective and the switch and
signal lamp in elevation with the electric connections between them.
Figure 3 is a detail view showing the preferred form of circuit closer.
Figure 4 is a view representing the circuits clearly.
The usual switch or signal lamp is represented at a as mounted upon a standard b
and as having the usual plain or coloured glasses c, c, c which are illuminated by
the lamp d within the lautern. In the upper portion of the lantern is fixed a
bracket e which supports at the proper distance above the lamp da circuit closing
device which consists of a U-shaped tube 8. In the bend of the tube is formed a
bulb fto receive a suitable quantity of mercury, while the two legs of the tube have
bores and f of small diameter. Within the bore f¹ is fixed a terminal, indicated
at, which is of such a length as to be always in contact with the mercury while its
upper end is suitably connected to an ordinary binding-post f. The other leg of
the tube is formed with a small bulb f above the narrow bore f' so that the
mercury may have opportunity to expand without danger of bursting the tube
after it has risen to that height in the bore fat which it stands normally when
the lamp d is burning. In the binding-post f* is supported a terminal f' which is
adjustable therein, as indicated, so that its extremity may be set higher or lower
as desired.
8

page_text: g
Within the signal box or at any other desired point is placed a box or casing g
which encloses the indicating devices, together with the battery h. The binding-
post of the thermostat is connected electrically by a suitable conductor k to
a binding-post m on the casing g, while the other binding-post f of the
thermostat is connected by a conductor with a common point m' from which
connection is made by a conductor to the battery and by a conductor k³ to a
post m² on the casing g the latter being connected to the point m³ of a switch m*.
Within the casing is fixed a magnet n which is connected on one side by a
conductor n' to the binding-post m and thence to the battery through the thermostat f
and on the other side by a conductor n² to a binding-post m³ and thence by a
conductor to the other side of the battery. The armature of the magnet n is
preferably adapted to swing on an axis parallel with the axis of the magnet, being
fixed to a spindle o'. This spindle projects through the front plate p of the
casing and bears upon its outer end a visual signal r. A normally open shunt,
including a bells of ordinary construction, and having a normally open circuit
closer, extends from the switch m² to the binding post m³ and the movement of the
armature o of the magnet n is adapted, when the armature is released, to close the
shunt at t.
i
As represented in Figure 1 the circuit closer t is of ordinary construction and is
actuated by a finger o² which is carried by the armature o.
The arrangement
shown in Figure 3 is preferred, however, because of its greater certainty in
operation although the armature is less heavily loaded. In this arrangement the
terminals of the shunt are counected respectively to mercury cups and v₁, and a
light wire bridge w is suspended by a link w¹ from the end of the semaphore or
signal arm r. As it is only necessary that the bridge w should descend in order to
close the shunt, no pressure being required, the movement of the armature may be
made still more easy by adding an adjustable counterpoise o³.
The operation of the devices above described will now be understood. So long
as the lamp d is burning properly the mercury in the thermostat f will make
contact between the terminals f³ and f and will therefore keep the circuit closed
through the magnet », thereby holding the signal arm r in the position shown, in
which it indicates that the lamp is burning. Should the lamp go out or burn low
or dimly the mercury in the thermostat will contract sufficiently to break the
circuit between the terminals and f. The armature o of the magnet n will
then be released, allowing the signal arm'r to move to the position shown by dotted
lines in Figure 1 in which it will indicate that the lamp is out. As the armature
moves, the shunt through the bell will be closed and the bell will then be rung
continuously until the shunt is broken by the opening of the switch m
obvious that the indicator will show trouble whether the lamp be entirely out,
or burning low or should the circuit be broken in any way, and that as soon as the
trouble has been removed, whatever its nature, the indicator will at once show
that fact.
It is
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. The combination with a switch lamp, a thermostatic circuit controller
supported in proximity thereto, a battery and a magnet in electrical connection
with said circuit controller, of a signal arm carried by the armature of said magnet,
a normally open shunt around said circuit closer and magnet adapted to be closed by
the release of said armature, and an audible signal included in said shunt,
substantially as shown and described.
2. The combination with a switch lamp and thermostatic circuit controller
supported in proximity thereto with a battery and magnet in connection therewith,
of an armature for said magnet mounted to swing on an axis parallel with the axis
of said magnet, a signal arm carried by said armature, a normally open shunt around
said circuit controller and magnet, an audible signal included in said shunt, and a

page_text: circuit closer in said shunt adapted to be actuated by the release of said armature,
substantially as shown and described.
3. The combination with a switch lamp, a thermostatic circuit controller få and
a battery h and magnet n in connection with said circuit controller, of an
armature o mounted on a spindle o¹, an arm fixed to said spindle, a shunt around
said circuit controller and magnet, mercury cups at the terminals of said shunt, a
bridge carried by said signal arm and adapted to descend into said cups, and a
bells in said shunt, substantially as shown and described.
Dated this 10th day of November 1894.
JOHN P. O'DONNELL,
Applicant.