Improvements in Electric Block Signalling Apparatus.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Block Signalling Apparatus.
I, WILLIAM PHILLIPS HALL, of Greenwich Connecticut, United States of
America Signal Engineer, 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 relates to automatic electric block signals for railways and it has
for its object to improve and simplify the operation of such systems and to reduce
the expense of operating such systems; and it consists of the devices herein shown
and claimed.
The accompanying drawings represent diagrammatically the invention as applied
to a series of blocks on a line of railway, including the first and last blocks of the
railway, A being supposed to be the first and the last block of the railway.
The greater number of blocks noturally found on any given installation in practice
would be equipped by duplicating indefinitely often the arrangement of circuits and
of instruments shown in connection with the intermediate blocks of the series
represented, as for instance with blocks marked C, D, E and F. In the installation
represented in the drawings the length of track is divided into separate sections
which are insulated from each other in the well known way, and are marked in the
drawings A, B, C, D, E, F and G. The trains are supposed to be moving upon the
track in the direction indicated by the arrows. Each track section has a battery
near the end of the same, marked respectively A¹, B¹, C', D', E³, F¹ and G', and
in the familiar way the rails of each section form a part of the circuit of the
battery pertaining to that section. The arrangement of devices will be best
explained by describing in order in connection with the drawings the successive
operations of a train upon those devices in passing over the sections of track
represented.
It will be understood that the length of the different sections may be anything
desired, as for instance a half mile each or varying lengths if desired at different
parts of the railway depending upon the frequency of trains, the presence of curves,
tunnels &c.
First operation-on train entering track section A. If track sections B and C are
clear of trains, the train entering A. in the well known way short circuits the current of
the battery A.' from the relay 1, demagnetizing that relay and closing at its
armature 2 the signal circuit of the signal S, the current of battery flowing
through said circuit and drawing the signal S to clear in the ordinary way. This
continues as long as any part of the train remains upon track section A. If,
however, track section B is occupied by a train, that train on 13 short circuits the
current of battery B' and demagnetizes relay 4 thus breaking at 5 the signal circuit
of signal S, so that in that case the operation of the train on A to close at 2 the
break there in the signal circuit of signal S does not close all the breaks in that
signal circuit (to wit, does not close the break at 5 caused by the train on track
section B) and so does not draw the signal S to clear but leaves it at danger. On
which the engineer of the train on track section A would stop on section A and
before signal S until it is cleared. Again if track section B is clear of trains
but C is occupied by a train, that train on C short circuits battery C¹ and
demaguetizes relay 7 thereby breaking at 8 the signal circuit of signal S, so that
in that case as before the signal S would not clear before the engineer of the train
entering section A. But while the latter train remains on section A (thus closing
at 2 the break there in the signal circuit of the signal S) then the moving of the
preceding train from section B (which closes at 5 the break there in the circuit of
signal S) and its subsequent moving also from section C (which closes at 8 the last
TDi Q77

page_text: remaining break in the signal circuit of signal S) operates to clear signal S in the
eyes of the engineer of the waiting train on A. He can then proceed, knowing
that track sections B and C must be clear of trains.
Second operation-on train entering track section B while track sections C
and D are clear of trains. The train short circuits the current of battery B¹,
demagnetizing relay 4. This breaks the signal circuit of signal S at 5 (sending
that signal to danger and keeping it there although another train enters A) and
makes the signal circuit of signal S' through battery 3 at 6 (drawing signal S¹ to
clear). If, however, there is a train on section C it will demagnetize relay 7 and
break at 8 the circuit of signal S¹, so that signal S' will not clear before the
engineer of the train entering section B. Similarly if there is a train on section D
that train will demagnetize relay 11 and so will demagnetize relay 12, and so will
demagnetize relay 7, thereby breaking at 8 as before the circuit of signal S¹, so
that that signal will not clear before the train entering B. The passage of the
train on section C from that section and from section D closes at 8 the breaks there
in the circuit of signal S' and causes that signal to clear before the waiting train
on section B.
Third operation-on train entering track section C, while track sections D, E
and F are clear of trains. The train short circuits the current of battery C¹ and
demagnetizes relay 7. This breaks the signal circuits of signals' S and S₁ at 8
(sending or continuing those signals at danger) and makes at 9 the circuit through
battery 10 of the signal S, (clearing that signal). If, however, there is a train on
section D it demagnetizes relay 11, breaking at 13 the circuit of signal S³, so that
that signal will not clear before a train on section C. Similarly if there is a
train on section E, it demagnetizes relay 14 breaking at 15 the circuit of signal S³,
so that that signal will not clear before the train on section C. Similarly if there
is a train on section F it demagnetizes relay 16 which breaks at 17 the circuit
of battery 18, demagnetizing relay 19 which breaks at 20 the circuit of battery E'
demagnetizing relay 14 which as before breaks at 15 the circuit of signal S2,
so that that signal will not clear before the train which is on section C. But
when the train on section D leaves that section, thereby closing the break at 13 and
also leaves sections E and F, thereby closing the break at 15, then the signal §²
will clear before the train waiting on section C.
Fourth operation-on train entering track section D, while sections E and F are
clear of trains. The train short circuits the battery D', demagnetizing relay 11.
This breaks at 21 the circuit of battery 22, which demagnetizes relay 12, which
breaks at 23 the circuit of battery C which demagnetizes relay 7, which breaks
at 8 the circuit of signal S', thus continuing that, signal at danger. The
demagnetizing of 11 also breaks at 13 the circuit of signal S2, throwing it to
danger. It also closes the breaks at 24 and at 9 in the signal circuit of signal S³,
(the latter by demagnetizing relay 7 as above), thus clearing the signal S³.
If, however, there is a train on section E, it demagnetizes relay 14 and breaks at 15
the circuit of signal S³, and so that signal cannot clear; and if there is a train on
section F, it demagnetizes relay 16 and by the break at 17 demagnetizes relay 19
and by the break at 20 demagnetizes relay 14 and so also breaks at 15 the circuit of
signal S and so that signal cannot clear. But when the train passes from
sections E and F then the break at 15 is closed and the signal S³ clears before
the waiting train on section D.
Fifth operation on train entering track section E, while sections F and G are
clear of trains. The train demagnetizes relay 14. This cuts off at 15 the current
of battery 10 from signals S' and S', continuing them at or sending them to danger.
It also closes at 25 the break there in the signal circuit of signal S*, the current
of battery 26 thereupon clearing that signal before the train. If, however, there
is a train on section F, it demagnetizes relay 16 and breaks at 27 the circuit of
signal S, thus preventing that signal from clearing before the train entering
section E. Similarly, if there is a train on section G, it demagnetises relay 28 and
so breaks at 29 the signal circuit of signal S*, thus preventing that signal from

page_text: clearing before a train moving on section E. But when the train passes from
section F, thus closing the circuit of signal St at 27 and also passes from section G,
thus closing that same circuit at 29, the signal S* clears and the train on section E
is at liberty to proceed.
Sixth operation-on train entering track section F, while track section G is
clear of trains. The train on F demagnetizes relay 16. This breaks at 27 the
circuit of signal S' and throws that signal to danger. It also breaks at 17 the
circuit of battery 18, demagnetizing relay 19, breaking at 20 the circuit of
battery E¹ and demagnetizing relay 14 which breaks at 15 the circuits of signals S
and S and continues them at danger. The demagnetizing of relay 16 also closes
at 30 and 25 (the latter through the demagnetizing of relay 14) the signal circuit
of signal S and thus clears that signal. If, however, there is a train on track
section G, it demagnetizes relay 28 breaking at 29 the circuit of signal S³ and so
preventing that signal from clearing before the train moving on section F. When
the train passes from section G it will close the signal circuit at 29 and the signal S
will clear.
In the particular arrangement of signals and signal circuits shown in the
drawings, which is the preferred arrangement, it is intended that each alternate
signal (S, S², S') shall be merely a green or cautionary signal which the engineer
is supposed to pass even while it is set out at danger, but to pass with a precautionary
notice to look out sharply for the next signal; and that the intervening signals
(S1, S³, S) should be absolute signals which the engineer is supposed never to pass
except when they stand at clear. The advantages of such cautionary signals are
many. It will be observed that the cautionary signal S³ cannot clear in front of a
train entering track section (unless track sections D, E and F are clear of
trains, whereas the absolute signal S³ will clear in front of a train entering track
section D if E and F are free of trains; so that an engineer seeing the cautionary
signal S clear before him knows that the alsolute signal S will also clear before
him. On the other hand the engineer having passed signal S' at clear (which
shows that sections C and D are clear of trains) and finding cautionary signal S² at
danger and failing to clear before him, knows that S' is at danger, not because of a
train on section D but because of a train on sections E or F, and so he runs by
signal S³ but is on the look out for danger at signal S³, for that signal S³ will not
clear before him unless the preceding train has left both E and F, and if that
signal does not clear before him he stops his train on section D until it does clear.
It is not essential to the main invention, however, that the intermediate signals
should be employed as cautionary signals or be affected by the action of the train
on the second or third succeeding rail circuits; and in such event the connecting
circuits and circuit-breakers effecting that end would be omitted.
It will thus be observed that in the broad invention the rail circuits are normally
closed and the signalling circuits-the circuits directly operating each signal--are
normally open or broken, being normally open or broken at a circuit-closer which
is constructed to be closed by the action of the train upon one of the rail circuits-
the one at or near the end of which the signal operated by that signalling_circuit
stands, and that the signalling circuit is also capable of being broken by one
or more normally closed circuit-breakers which are constructed to be opened by
the action of a train on one or more of the next succeeding rail circuits of the line.
It will also be observed that in the invention as embodied in its preferred form the
rail circuits are as before normally closed and the signalling circuits normally
open and open as before at a circuit closer which is constructed to be closed by the
action of a train upon one of the rail circuits, and that the signalling circuit
is also capable of being broken by normally closed circuit breakers which are
constructed to be opened by the action of a train on either of the next two
succeeding rail circuits of the line, the alternate signalling circuits having circuit
breakers constructed to be opened by the action of a train on either of the next
three succeeding rail circuits of the line.
It will be understood that the visible signals S, S', S' &c. may be replaced by

page_text: ·
audible signals or by both audible and visible signals, without departing from my
invention; also that the said signals may be replaced by electric locks or inter-
locking devices, as parts of a larger system, without departing from my invention;
also that said signals &c. may be operated either directly by the current flowing in
the signalling circuits of the invention or indirectly by those currents, as, for
instance, the signals may be directly operated by steam or pneumatic power or by
the current of a dynamo or a storage battery or other source of current, and said
power be directed and controlled by the current flowing in the signalling circuits of
the invention, without departing from my invention. And it is understood that the
construction of the relays and of the signals themselves and their operating
mechanisms may be greatly varied without departing from my invention.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a block signalling apparatus, the combination with a series of normally
closed rail circuits, of a series of normally open or broken signalling circuits, cach
signalling circuit including a normally open circuit-closer constructed to be closed
by the action of the train upon one of the rail circuits and also including a normally
closed circuit breaker constructed to be opened by the action of the train upon the
next succeeding rail circuit of the line, substantially as and for the purpose
set forth.
2. In a block signalling apparatus, the combination with a series of normally
closed rail circuits, of a series of normally open or broken signalling circuits, each
signalling circuit including a normally open circuit-closer constructed to be closed
by the action of the train upon one of the rail circuits and also including normally
closed circuit-breakers constructed, on each alternate signalling circuit, to be
opened by the action of the train upon the two next succeeding rail circuits of
the line, and on the intermediate signalling circuits to be opened also by the
action of the train on the third succeeding rail circuit of the line, substantially as
and for the purpose set forth.
Dated this Second day of February 1892.
WILLIAM PHILLIPS HALL.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.