Improved System of Electrically Interlocking Signals and Points, and in Apparatus therefor.
Year: 1893

page_text: Date of Application, 9th Mar., 1893
Complete Specification Left, 11th Dec., 1893-Accepted, 20th Jan., 1894
PROVISIONAL SPECIFICATION:
Improved System of Electrically Interlocking Signals and Points,
and in Apparatus therefor.
I GEORGE EDWIN FLETCHER of The Homestead Cale Green, Stockport, in
the County of Chester, Electrician, do hereby declare the nature of this invention
to be as follows:-
The object is to provide means for electrically controlling the operating of
signals and points in such manner that a signal cannot be given or set at line clear,
or points operated until such signals as are necessary for the safe conduct of the
traffic have been given or placed so as to block the required section.
In order that the above object may be attained, it is necessary that the action of
the electric currents shall be such that the action of an attendant at one station
cannot be reversed without the concurrence of an attendant at another station,
and further it must be provided for that any accident to the circuits either by
breaking a circuit or reversing a current cannot unlock the signalling or points
mechanism.
In carrying my invention into effect to interlock two signals or signalling and
points locking mechanism, I employ in combination a line circuit and two local
circuits.
The local circuits are normally continuous in action and the line circuit acts
conjointly and simultaneously with each local circuit to produce or allow the
desired locking and unlocking of the signals and points according to the direction
of the line current. The combination being such that a failure or reversal of
either or both of the local circuits results in the necessary locking to prevent
accident, whilst the failure of the main circuit would also cause locking.
When the signals or points or both require to be controlled from an additional
point or points one or both of the local circuits is or are extended to either or
both points.
Apparatus under my invention is combined with any usual signalling points or
block telegraph mechanism and consists of line current commutator, automatic
locking devices controlled by electro magnets having a closed magnetic circuit,
such magnets being so wound and connected with the line and local circuits that
both a main line current of specified direction and a local current must pass
through the coils of the electro magnets to obtain unlocking. There is further
combined with the above appliances circuit breaking and making devices controlled
in their motions by the position of the signal and points levers where necessary.
When desirable the signals are connected mechanically or electrically so as to
be placed at danger by the passage of a locomotive or train.
Dated this 8th day of March 1893.
COMPLETE SPECIFICATION.
Improved System of Electrically Interlocking Signals and Points,
and in Apparatus therefor.
I GEORGE EDWIN FLETCHER of The Homestead, Cale Green, Stockport in
the County of Chester, Electrician, 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 :―
The object is to provide means for electrically controlling the operating of

page_text: signals and points in such manner that a signal cannot be given or set at "Line
clear," or the points operated until such signals as are necessary for the safe
conduct of the traffic have been given or placed so as to block the required
section.
In order that the above object may be attained, it is necessary that the electric
currents shall be such that the action of an attendant at one station cannot be
reversed without the concurrence of the attendant at another, and further, it
must be provided that any accident to the circuits either by breaking a circuit or
reversing a current cannot unlock the signalling or points mechanism.
In carrying my invention into effect to interlock two siguals or signalling and
points locking mechanism, I employ in combination a line circuit and two local
circuits.
The local circuits are normally continuous in action and the line circuit acts
conjointly and simultaneously with each local circuit to produce or allow the
desired locking and interlocking of the signals and points according to the
direction of the line current. The combination being such that a failure or
reversal of either or both of the local circuits results in the necessary locking to
prevent accident, whilst the failure of the main circuit would also cause locking.
When the signals or points, or both require to be controlled from an additional
point, or points, one or both of the local circuits is or are extended to either or
both points.
Apparatus under my invention is combined with any usual signalling points or
block telegraph mechanism and consists of line current commutator, automatic
locking devices controlled by electro magnets having a closed magnetic circuit,
such magnets being so wound and connected with the line and local circuits that
both a main line current of specified direction and a local current must pass
through the coils of the electro magnets to obtain unlocking. There is further
combined with the above appliances circuit breaking and making devices
controlled in their motions by the position of the signal and points levers where
necessary.
When desirable the signals are connected mechanically or electrically so as to be
placed at danger by the passage of a locomotive or train.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a diagram showing my improved system of interlocking a signal cabin
with the points of a siding, the siding points, or signal, or both to be controlled, is
or are at a. the rear signal cabin is at b, and the signal-cabin in advance, is at c.
At 6 there is a local battery d connected by wires e to one coil of a ring or closed
circuit-electro magnet at cabin b. The electric current from the said battery d
continuously flows through the said coil f. g, is a main line battery connected by
wires to commutator i. From the said commutator one wire j passes to earth or
to a return wire k, whilst the other wire passes through the coils of an electro
magnet m, and indicator n, to the coil f' of the ring or closed circuit electro magnet
at cabin b, thence the circuit continues through the wire o to the coil p, of the ring
or closed circuit magnet at the siding a, thence through the wire o', indicator 9,
connection spring r, and wire o² to the return wire k, so completing the circuit.
"The two currents from the batteries d, and g, through the coils f and f', cause the
pole piece of the ring magnet to attract a latch, such as s, and leave a signal
levers free to be moved. The latch s is held in locking position by the action of
gravity, or the resilience of a spring. t, is a local battery at cabin e connected at
one end to the return wire k, and at the other by a wire u, through the indicator v
and electro magnet w to the key stop r the key which works in conjunction with
the stop is connected to the contact piece a². 3³, is a second contact piece con-
nected to the wire u. y, is an armature contact maker operated by the electro
magnet w to close the circuit between the contact pieces, is a wire which
connects the stop & and contact maker with an indicator = and one pole p¹ of a
ring magnet. represents a latch interlocked by the magnetism of the pole

page_text: piece p² of the ring magnet and locked by a weight or spring. ³ represents the
points lever locked and released by the said latch.
C
As shewn by the drawing, the lever s³, is locked by the latch s², in such position
that the points are closed and the main line is open. If it is now desired to open
the points for shunting purposes, the attendant at cabin b places the main fine
signal to "Danger" if not already in that position, and in moving the operating
lever to do so he uncovers an aperture in connection with the commutator i. A
key is inserted in the aperture and the commutator is moved so as to reverse the
line current. The commutator is held in the position in which it is placed by the
key by the action of the electro magnet m, and cannot be moved back to the original
position by the key. The reversal of the main line circuit through the coil f¹,
renders the pole piece f inactive, thus releasing the latch s which locks the signal
lever s¹. At the same time, the reversal of the said main line current in the coil
renders the pole piece p³ active, thus attracting the latch s and releasing the lever s*
if there is no further control required and the other coil pl is in connection with a
local battery. If however further control is required say from cabin in advance,
the local battery is placed at cabin c and brought into action by means of the key r¹
being closed against the contact piece_x. When the key is closed a current
passes through the electro magnet w and coil p', and is maintained by the contact
maker y, being drawn into contact with the pieces 2 and 3 by the action of the
electro magnet w. The main line signal-lever s' is now locked at danger whilst
the points lever is free to be moved as required. If now it is desired to open the
main line the points must be closed. In doing so the operating lever is moved
until an aperture leading to the connection springs r, r, is uncovered. A key r²
may now be inserted through the said aperture and the springs r, r³, pressed away
from their contact pieces. The main line circuit is thus broken and the pole
piece p² is rendered inoperative so that the latch 2 locks the lever s³, whilst the
commutator i returns to its original position and the pole piece is rendered active
whereby the latch s is withdrawn, allowing the main line signal to be moved. The
circuit through the magnet w is also broken, and the piece y returns to its original
position.
Fig. 2 is a diagram showing my improvements applied to the usual block signals.
Here four stations a, b, c, and d, are shown connected. The locks
marked 1, 1ª, 1, 1º, 1ª, 1º, are identical with those already described both in
form and action. Supposing it were required to start a train from a, and allow it
to pass through the whole length of the system, before the attendant in cabin a can
take off the signal connected with lock 1, it is necessary that he should have a line
clear current from the instrument 2 which is put on by actuating the commutator 3ª.
This causes a current to pass through the coilf of the lock 1, and the coil f' of the
lock 1 at the same time through the relay 4, which puts on the local current
through the coil f¹ of the lock 1, and the latch is drawn back by the pole piece ƒ³
and the signal lever is released so that the attendant in cabin a can take off his
signal to allow the train to start. But as soon as he receives a train on line current
from b, the latch falls back into locking position so that so soon as he places his
signal to danger if he has not already done so, it is locked at danger and can only
be again taken off by a line clear current, before b can take his signal off to allow
the train to proceed towards c it is necessary that a line clear current should be
sent from c by 3° and received at 6 on 25 passing through 1 coil on lock 1*.
The current from 6 to a will be seen to be passing through the coil fl of the,
lock 1º.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
:-
First. Electrically interlocking railway signals, and signals and points by means
of two local and one main line circuit operating conjointly substantially as set-
forth.

page_text: Second. Apparatus for interlocking railway signals and signals and points con-
sisting essentially of two or more ring or closed circuit electro magnets and latches
combined with local and main line circuits and operating devices substantially as
set forth.
D. oil
Decembar 1902
Per pro J. T. KING,
J. Johnson,
Agent.