Improvements in Electric Signalling Apparatus and Systems for Railways.
Year: 1893

page_text: Date of Application, 15th Apr., 1893-Accepted, 1st July, 1893
COMPLETE SPECIFICATION.
Improvements in Electric Signalling Apparatus and Systems for
Railways.
I, JAMES YATE JOHNSON of 115 St. Vincent Street, Glasgow in the County of
Lanark North Britain, Chartered Patent Agent (a communication to me from
abroad by Jacob William Lattig, Electrical Engineer, and William Frederick
Detwiller Pascoe, Manufacturer, of Easton in the State of Pennsylvania, United
States of America), 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 signal operating apparatus contemplates the employment of an electric
motor for actuating the signal operating mechanism in order to move the signal to
safety. The circuit through which the current is supplied to the motor includes
contacts which are controlled by a relay included in a constantly closed track
circuit, the arrangement being such that the contacts in the motor circuit will be
opened whenever a train reaches the track section forming part of the track circuit
including that relay, in which event the current will be short circuited through the
wheels of the train, the track relay will be de-energized, the contacts in the motor
circuit will be opened, the motor will thus be de-energized and the signal will be
free to rise to danger which it does by reason of its counter weight, the motor
armature revolving backward as a mere idler. As soon as the train passes beyond
the section, the track relay is again energized, and closes the motor circuit, and
the motor is at once put into action to lower the signal, which it does until the
latter reaches safety position at which time the motor will be stalled and incapable
of further moving the signal (because the latter at that point brings up against
the usual stop) but will still act to hold the signal in safety position.
The plan thus far described contemplates a motor circuit which is closed at all
times except when a train is on the track section appropriate to the signal. This
would not be objectionable if the motor were supplied with current from a dynamo,
which could be used to supply a large number of inotors in a signal system. But
in case the current is supplied from batteries, in which event each motor would
have its own battery, then in order to prevent useless expenditure of energy and
consequent exhaustion of the battery to which it would be more particularly liable
if, as prefer, it should be of low internal resistance, I prefer to add to the parts
already described, means for breaking the motor circuit as soon as the motor has
done its work, and a detent for holding the signal operating mechanism in the
safety position to which it has been brought by the motor. To this end I place in
the motor circuit a second set of contacts, which are controlled, through a suitable
intermediary, by or from the signal operating mechanism in such a manner that
they shall be opened whenever that mechanism reaches safety position; and I
superimpose upon the system of circuits already described a third or locking and
releasing circuit containing contacts controlled by the relay of the track circuit,
so that the said locking and releasing circuit shall be closed at all times except
when a train is on the track section, and the track relay consequently is short
circuited, and including an electro-magnetically controlled detent, which, called
into operation by the locking and releasing circuit when the latter is closed, engages
and locks the signal operating mechanism after it has been brought to safety
position, and so holds it until the next opening of the locking and releasing circuit
due to the entrance of another train upon the block or track section.
In approved systems of automatic block signaling, it is usual to provide each
block with two signals, a danger signal and a caution signal, the danger signal for

page_text: example going to safety when and as soon as the train passes the block appropriate
to that signal, but the corresponding caution signal remaining at danger and not
going to safety until after the train has passed the next block beyond. This
provision can be readily made under the present invention, by providing in addition
to the danger signal and system of circuits therefor as above described, a second
or caution signal with a second system of circuits similar to those already described
for the danger signal, save that in the caution signal system the primary controlling
circuit corresponding to the track circuit of the danger signal system, is a grounded
circuit having no connection with the track, and further contains two sets of
contacts controlled, the one by the danger signal operating mechanism of that
block to which the caution signal pertains, and the other by the operating
mechanism of the danger signal pertaining to the next block beyond, the arrange-
ment being such that both sets of contacts are closed only when the danger signal
mechanism appropriate to each set is in safety position. Thus the caution signal
can be brought to safety only after the danger signal of the next block beyond has
been brought to safety, which can be only after the train has passed that block.
In the accompanying drawings, to which I will now refer for a more complete
understanding of the improvements and the manner in which they may be carried
into practical effect,
Figure 1 is a side elevation of a signal post and signal appliances thereon
organized and arranged in accordance with the invention with a diagramatic
representation of a system of circuits applicable thereto.
Figure 2 is a like view of a modification.
Figure 3 is a like view of a still further modification, with a locking and releasing
circuit, and an electrically controlled detent superadded to the appliances repre-
sented in the preceding figures.
Figure 4, is a diagramatic representation of an automatic block system of danger
and caution signals and circuits therefor in accordance with the invention.
Figure 5, is an enlarged view of one of the signal posts and signal appliances
and circuits therefor used in the system represented in Figure 4.
Figures 6, 7 and 8 are details of the appliances represented in Figure 5.
In Figure 1, A is a signal pole carrying the usual pivoted counterweighted
semaphore blade B. C is an electric motor mounted on the side of the pole, and
having on its armature shaft a drum to which is secured a cord or other suitable
pliable connection a, having its other end fast to the extremity of the longer arm
of a lever b, pivoted to a supporting bracket s, fast to the side of the pole, and
'having its shorter arm joined by the vertical connecting rod d to the counter-
weighted side of the pivoted semaphore blade. When the motor is inactive, the
signal rises to and stands at danger. When the motor is energized the rotation of
its armature coils the cord a around the drum on the armature shaft, thus pulling
down the longer arm of the lever b, and consequently forcing up the connecting
rod d, the result being that the semaphore blade will be caused to drop, until its
counterweight in rising brings up against the signal pole, which will not be until
the signal is at safety. When this takes place the motor will be stalled and
incapable of further motion, but it will still act to hold the blade in safety position,
until the supply of current is cut off from it, at which time the counterweight will
act to pull the signal to danger, the cord a at this time being drawn on by the
lever so as to cause it to revolve the armature backward as an idler.
The circuit arrangements are as follows:
The track circuit 1 is a constantly closed circuit; it includes the relay D and is
completed through the rails of the insulated track section or block X. The motor
circuit 2 includes the motor C, and a pair of contacts a controlled by the armature
of track relay D, the arrangement being such that so long as the relay is energized
(which it will be so long as the block or section X is clear) the contact will be
closed, and consequently the motor will be energized and will operate to move the
signal to safety and hold it there. As soon however as a train, typified at Y enters
the 'block X, the track circuit will be completed through the path of lower

page_text: resistance afforded by the car wheels and axles, the relay D consequently will be
cut out or short circuited, its armature will drop, thus opening the contacts and
breaking the motor circuit, and the motor will at once become inactive and allow
the signal to rise to danger, this condition of affairs continuing until the train has
passed beyond the block at which time the normal condition of the circuits will be
restored, and the signal will go to safety.
The arrangement of appliances and circuits in Figure 2, is the same as in
Figure 1, save that, for the purpose of gaining in power (with of course a pro-
portionate decrease of speed) the cord a by which the lever is pulled down is
attached to a drum a' fast on the axle of a pulley a², belted to the armature shaft
of the motor C.
Figure 3 contains the same arrangement as in Figure 2, (the pulley a² being a
sprocket wheel and the belt a³ being a sprocket chain engaging a sprocket wheel
on the motor armature shaft), and like reference letters and numerals indicate like
parts in the two figures. I have added however to the system of circuits and
appliances in this figure, a third circuit for controlling means for locking and
releasing the signal operating mechanism, and means for breaking the motor
circuit after the motor has brought the signal to safety.
The locking and releasing circuit is indicated at 3. It has in it contacts y which
are controlled by the armature lever of the track relay D, and open and close
simultaneously with the contacts of the motor circuit, being of course insulated
from the latter contacts; and it further includes a relay E, the movement of the
armature lever of which closes and opens a second pair of contacts in the motor
circuit 2. This armature lever also carries a prong or detent c which is intended
to enter or engage at the proper time a notch c¹ in the periphery of a disc a fast
to a spur wheel as mounted in suitable bearings and engaging and driven by a
pinion a fast on the same axle with the drum a'. These parts are so arranged
and proportioned that when the notch c' comes opposite to the detent c, the motor
will have pulled down the signal to safety. And the arrangement of the contacts
in the motor circuit is such that the upward movement of the armature lever to
carry the detent into the notch (a movement permitted by the signal operating
mechanism only when the signal has been lowered to safety) will suffice to separate
the contacts and thus to open the motor circuit at that point.
As
In the position of parts shown in Figure 3, a train Y is supposed to be on the
block X. This being the case, the track relay will be cut out, the contacts & and y
consequently will be separated, thus breaking the circuits 2 and 3; the armature
lever of the de-energized locking and releasing relay E will have dropped,
releasing the signal operating mechanism from the detent, but closing the second
break in the motor circuit at, and the signal by its counterweight will have been
brought to danger. This is the position of parts represented in the figure.
soon however as the train passes beyond the block, the track circuit is restored
through the track relay; the motor and locking and releasing circuits 2, 3, are
closed at the points and y (the other break in the motor circuit having
previously been closed as above explained); the motor acts through the signal
operating mechanism to lower the signal to safety. The now energized locking
and releasing relay magnet E attracts its armature lever, but can draw it up only
as far as permitted by the detent which is arrested by the unbroken portion of the
periphery of the revolving disc a against which it bears, this slight movement of
the armature lever being insufficient to separate the contacts 2 (the back one of
which is a spring contact adapted to follow the other a certain distance); and this
condition of affairs continues until the signal is at safety. By this time the disc a®
will have revolved far enough to bring the notch c' opposite the detent c, con-
sequently the attracted armature of the relay magnet E is free to rise, and in so
doing it simultaneously engages the detent with the disc a', thus locking the
signal at safety, and separates the motor circuit contacts at z, thus breaking the
motor circuit, which continues open until the locking and releasing relay magnet E
is de-energized. The locking and releasing circuit however continues closed, for

page_text: the purpose or holding the armature of the relay E up, and will so remain until
the track relay D is again de-energized.
Thus of the two sets of contacts in the motor circuit the one is directly
controlled by the track relay. The other z however is controlled by or from some
moving part of the signal operating mechanism, which will not permit any movement
of separation until the signal has reached safety position, at which time their
separation is permitted, thus saving expenditure of battery energy further than
that required to cause the motor to move the signal from danger to safety.
In Figure 4 I have represented the general system of appliances represented in
Figure 3 extended to an automatic block system embracing danger and caution
signals for each block, the arrangement being such that the danger signal (like the
signal in the preceding figures) is automatically brought to danger when the train
enters the block appropriate to that signal and to safety when the train quits that
block, but the corresponding caution signal, while brought to danger by the
entrance of the train on the block, is not restored to safety until the train passes
beyond the next block in advance.
To attain this result I have duplicated for the caution signal the same general
system of circuits and appliances as that employed in Figure 3 for the danger
signal, with such modification in the initial or primary caution signal circuit
(corresponding to circuit 1 of the danger signal system) as required in order to
adapt the caution signal to its somewhat different use. I have also modified in
some respects the arrangement and structural details of some of the mechanical
and electro-mechanical appliances in the system, although in principle and in
general mode of operation they remain in substance the same as those already
described.
In order that these differences may be more clearly understood I will first
describe by reference to Figures 5 and 8 the construction and arrangement of the
parts on one of the signal poles in Figure 4.
Figure 5 represents the pole in side elevation.
Similar reference letters and numerals indicate like parts in all the figures 1 to 8
inclusive of the drawings.
There are two signals on the pole, the upper one B a danger signal, the lower
one B¹ a caution signal.
There are two distinct sets of signal operating mechanism on the pole, these two
sets so far as concerns their mechanical features being exactly alike, so that a
description of one will answer for both. The upper set is connected to and
operates the danger signal, the lower set is connected to and operates the caution
signal.
The danger signal system of circuits 1, 2, 3, is the same as previously described,
save that the contacts z of the motor circuit are somewhat differently located, this
however being a mere difference of detail.
The drum a' on which the signal lowering cord a is wound is secured on the axle
of a spur wheel a connected by gearing as, as, a¹0, with the armature shaft of the
motor. This system of gearing is shown in front elevation in Figure 6. The
pinion a¹ is loose on the armature shaft, and at the proper time is connected thereto
by the moveable clutch member d, which has teeth to engage corresponding teeth on
the contiguous face of the hub of pinion a¹. The moveable clutch member d has a
longitudinal spline and groove connection with the armature shaft so that while
rotating with the shaft it can slide lengthwise of the latter, to and from the
pinion a. The moveable member d is pressed up into engagement with the
pinion al by a vertical shifting yoke e (shown in front elevation in Figure 7)
which is attached to the pivoted horizontal armature lever of the locking and
releasing magnet E and projects up so as to straddle the armature shaft of the
motor and to bear against the outer end of the moveable clutch member d.
When the locking and releasing magnet E is energized the movement of its
armature consequent thereon. will move the shifting yoke e in a direction to
cause the clutch member d to engage the pinion a¹ thus coupling the latter to

page_text: the motor armature shaft, and consequently causing the signal operating
mechanism to lower the signal to safety. Whenever after this the locking and
releasing magnet E is de-energized and its armature is free to fall back, the
pinion a will be uncoupled from the armature shaft, and the signal by its
counter weight will be placed at danger. The weight of the counterweight is
such that while sufficient to overcome the friction of the gears from a to a
inclusive, it will not be sufficient to overcome that friction plus the inertia of
the motor armature; and consequently so long as the armature shaft is coupled
to the pinion alo, after the signal has been brought to safety, the signal operating
mechanism will be held in safety position, the clutch member d constituting in
effect the electro-magnetically controlled detent (corresponding in function to the
detent c of Figure 3) by which this result is secured.
In lieu of the clutch just described, an electro-magnetic clutch can be used,
comprising an electro-magnet which takes the place of the toothed hub of the
pinion a, and an armature moveable to and from the electro magnet, and taking
the place of the moveable clutch member d. In this case the locking and releasing
magnet E and its armature would be dispensed with; and the electro-magnet
forming one member of the magnetic clutch would be substituted for magnet E in
the locking and releasing circuit 3.
The break in the motor circuit at is controlled by two spring contacts z and a
conducting sleeve mounted on but insulated from a vertical rod 6' supported and
adapted to slide in bearings on the bracket supports and connected to and actuated
by the lever b as shown more plainly in Figure 8, the arrangement being such that
by the time the lever b has been pulled down far enough to bring its signal to safety
the rod 6 will have descended far enough to carry the contact sleeve ¹ down and
beyond the contacts z, thus breaking the motor circuit.
Thus far the two sets of electrical and mechanical appliances, the one for the
danger signal, and the other for the caution signal are precisely alike in con-
struction, arrangement and mode of operation, save that the sliding rod b₁ of the
danger signal mechanism carries on it two conducting sleeves m', n', insulated from
each other and from the sleeve ¹ and intended to operate, for the purposes to
be presently described, in connection with contacts m and n respectively, these
parts m, ml and n, n' being absent from the caution signal mechanism.
Also the caution signal circuits 2x, 3x, are like the corresponding circuits 2, 3,
of the danger signal system in function and purpose and include the same kind of
electrical appliances. The caution signal primary circuit 1 however differs from
the corresponding danger signal primary circuit or track circuit 1, firstly, in that
it is a grounded circuit, or a circuit including no portion of the track, and secondly,
in that it contains two sets of contacts m, m³ and n, n', controlled the one by the
danger signal mechanism of the same block and the other by the danger signal
mechanism of the block next beyond, the arrangement being such that both
danger signals must be at safety before the caution signal primary circuit is closed.
Thus each danger signal operating mechanism controls two sets of caution signal con-
tacts, the one set m, m' pertaining to the caution signal primary circuit of the same
block, the other set pertaining to the caution signal primary circuit of the next
block in rear as will be clearly understood by reference to Figures 5 and 8.
It will there be seen that by the time the danger signal is lowered to safety
the rod will be caused to descend far enough to close both sets of contacts m, m¹
and n, n' while at the same time or an instant before the contact sleeve z¹ passes
from between contacts z, thus opening the danger signal motor circuit. The
momentum of the armature of the danger signal motor, after the motor circuit is
opened, will suffice to carry down the rod 6 still farther in order to insure the
break at in the motor circuit, as well as complete closure at m and n.
With this explanation the operation of the automatic block system of danger and
caution signals illustrated diagramatically in Figure 4 will be readily understood.
I have there represented three blocks X1, X2, X, each with a system of appliances
and circuits such as described with reference to Figures 5, 8, and the train Y is

page_text: supposed to be on the furthest block in advance, X³, moving in the direction of
the arrow. Under these conditions the signals will stand as shown. In other
words the clearing of blocks X1, X2, has brought the danger signal of each one
of these blocks to safety, thus closing the primary circuit 1 of the caution signal
of block X through the contacts m of that block and the contacts n of block X².
Consequently the caution signal of block X' is also at safety. But the caution
signal of block X' is still at danger because while the contacts m of its primary
circuit are closed by bringing the danger signal of block X2 to safety, the
contacts n of said circuit, which are controlled by the danger signal mechanism
of block X are still open, this being due to the fact that the train is on block X³
and the danger signal of the latter block is consequently at danger. As soon as
the train clears block X3, and not until then, the caution signal of block X2 will be
brought to safety and so on.
In case it should not be desired to break the motor circuit immediately after the
motor has done its work, then the contacts 2, the locking and releasing circuit 3,
and the electro magnetically controlled detent would be dispensed with, and the
motor circuit 2 would be similar to that shown in Figures 1 and 2.
In conclusion I state that I do not limit myself strictly to the particular
construction and arrangement hereinbefore described, of the mechanism employed
in carrying out the invention. It may also be observed that in lieu of the
particular type of electric motor represented I may use a solenoid or other known
and suitable form of electro magnetic motor to be actuated or controlled as
herein before described through the agency of the motor circuit 2, and having its
moving part connected by suitable intermediaries to the signal.
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 :
1st. In an automatic railway block system of danger and caution signals, the
combination with a series of blocks, each having a danger signal normally at
safety, and danger signal operating mechanism controlled from a track circuit to
bring the signal to danger so long as a train is on the block, of a caution signal
for each block, operating appliances therefor, and a primary caution signal circuit
for controlling the action of said appliances, separate and distinct from the track
and track circuit, and completed through two sets of contacts, controlled the one
by the danger signal mechanism of the same block and the other by the danger
signal mechanism of the block next in advance, substantially as and for the
purposes herein before set forth.
2nd. An automatic railway block system of danger and caution signals comprising
for each block a danger signal, a track circuit therefor, a relay included in the track
circuit, a motor circuit completed through contacts controlled by the track relay,
and including an electric motor connected to and adapted to operate the danger
signal, in combination with a caution signal, a primary circuit therefor, separate
and distinct from the track and track circuit, including a relay and completed
through two sets of contacts controlled the one by the danger signal mechanism of
the same block, the other by the danger signal mechanism of the next block in
advance, and a motor circuit completed through contacts controlled by the relay
in said primary circuit, and including an electric motor connected to and adapted
to operate the caution signal, substantially in the manner and for the purposes
herein before set forth.
3rd. The combination of a railway signal, and operating mechanism therefor; a
primary circuit; a relay included in said circuit; a locking and releasing circuit
completed through contacts controlled by the primary circuit relay and including
an electro-magnet; a detent for engaging the signal operating mechanism controlled
by said electro-magnet; a motor circuit completed through two sets of contacts
controlled the one by the relay of the primary circuit and the other by or from the
signal operating mechanism; and an electric motor included in said motor circuit,

page_text: and connected to the signal operating mechanism, the combination being and acting
substantially as hereinbefore set forth.
4th. The combination of a railway signal, and operating mechanism therefor; a
primary circuit and a relay included in said circuit, a motor circuit completed
through two sets of contacts controlled the one by the relay of the primary circuit
and the other by or from the signal operating mechanism and an electric motor
included in said motor circuit and connected to the signal operating mechanism,
substantially as and for the purposes herein before set forth.
5th. The grounded primary circuit 1* of the caution signal, completed through
two sets of contacts m, m¹ and n, n¹, of which the moveable member of one is
connected to and operated by the danger signal mechanism of the same block to
which the caution signal of that circuit pertains, and the moveable member of
the other similarly is connected to and operated by the danger signal mechanism
of the block next in advance substantially as set forth.
Dated this 14th dor of Anril 1802
J. Y. JOHNSON,
115, St. Vincent Street, Glasgow, Applicant.