Improvements in or connected with Railway Signals or Signalling Apparatus.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in or connected with Railway Signals or Signalling
Apparatus.
I, JAMES YATE JOHNSON of 47 Lincoln's Inn Fields, in the County of
Middlesex Gentleman, do hereby declare the nature of this invention (which has
been communicated to me from abroad by Jacob William Lattig and William
Frederick Detwiller Pascoe both of Easton in the State of Pennsylvania, 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 relates to railway signalling apparatus in which the signal operating
mechanism is provided with a mechanical brake at some point between the signal
and the signal operating lever, in combination with means for closing the brake,
and an electro-magnet for controlling the operation of the brake or clamp closing
means the arrangement being such that so long as the magnet is inactive, the
brake in the signal operating mechanism will be open and incapable of closure by
the brake-closing means, and the signal, if not already in danger position, will
be returned to and maintained in danger position, or in that position (what-
ever it may be) which it is intended it shall assume whenever the magnet is
inactive.
This invention, so far as the apparatus is concerned, relates mainly to the means
for closing the brake. The brake itself may be formed by dividing one of the
operating rods of which the connections are composed, and forming the adjoining
ends of the two divisions in such manner that they will engage each other so long
as they are pressed together. The brake closing means consists of a clamp-like
guide, the walls or one of the walls of which can yield whenever desired, but
which so long as they are rigid and unyielding will press together and hold in
engagement the two ends of the said divided rod or brake which can slide
freely between them. The members or one of the members of the clamp may
be rendered movable or fixed, according as the magnet is inactive or active-the
magnet for this purpose controlling a latch or lock by which when the magnet is
active, and only then, the movable member of the clamp is locked tight in its
clamping position.
The apparatus constructed according to this invention is susceptible of wide and
varied use in single and double railway track block systems in which the circuit
for controlling the magnet may or may not be in part of the track rails; or
in connection with the home and distant signals of ordinary interlocking towers.
Some of its more important applications will be hereinafter, illustrated and
described.
And in order that the said invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to the
several figures on the annexed sheets of drawings the same letters of reference
indicating corresponding parts in all the figures.
Figure 1 is a fongitudinal vertical section of the more important parts of the
mechanism for operating and controlling the signal.
Figures 1A, 1B, 1C, 10 are details.
Figure 2 represents the invention as embodied in a railway signal system
where the traffic, as on a double track railway is in one direction only on each
track.
Figure 3 shows the invention applied to a system of railway signalling
where the traffic, as on a single track railway, is in both directions on the same
track

page_text: Figure 4 represents tlie invention as applied to a system in which the electric
circuit containing the magnet is not formed in part of the track rails.
Figure 5 represents the invention as applied to a system where it is designed to
act in effect as a trip to place, the signal to danger automatically under certain
conditions.
In order to understand the systems illustrated in Figures 2, 3, 4 and 5, it will
be necessary to first understand the construction and operation of the system..
illustrated in Figure 1 and which will now be described.
C is the signal arm pivotted in the usual way to the pole D and carrying the
semaphore E. It is represented in its normal or danger position in which position
it is brought and held by the weight T.
B', B, F, G. H are portions of the signal operating connections or mechanism-
leading from the signal arm C to the operating lever in the tower in the usual
way. The brake in this arrangement is situated between the parts B and F.
A is a box containing the magnet P and the parts of the apparatus with which
it is in more immediate operative connection.. In practice it is preferred to attach
this box to the signal pole D as shewn so as to be out of tampering reach; but it.
may be inserted in any suitable position on the line of rods or pipes leading from
the tower to the signal arm.
The part B is a toothed slide bar (shewn in perspective in Figure 1) which
passes up through an opening in the top of the box A, and is prevented from
moving in a lateral direction by guides s, st, s². The part F (shewn in perspective,
in Figure 1B) is also a toothed slide bar-the teeth of the two bars F, B, facing.
cach other so that they will interlock or engage when pressed together. The:
bar is jointed to the end of the rod G which projects into the box A through,
the bottom and between guides 3, s. This hinged toothed bar F is held inengage-
ment with the bar B, by a lever J (shewn in perspective in Figure 1°) which is-
pivotted at to the interior of the box A and bears upon the rod or projection I
on the back of bar F.
This lever J forms the member of the clamp herein before referred to as being
capable of being rendered fixed or movable the stationary member of the said.
clamp being the fixed guide s².
To hold the lower and free end of the lever J, fixed, a latch L is employed.
consisting in this instance of an angle lever hung at its elbow in the box A on a
horizontal pivot m with its shorter arm arranged to extend up just behind the
lower end of the lever J. The longer arm of this latch lever extends, across
the path of the toothed bar F, and is at this point forked or slotted. (as shewn
in the perspective view Figure 1) to clear the said bar and allow it freedom to
swing into and out of engagement with the toothed bar B.
To hold the latch lever L in position to prevent the clamp lever J from moving
outwardly, a detent is provided which in this instance consists of a hook, n, on the
upper end of the pivotted lever O, which carries or constitutes the armature of the
electro-magnet Pthe arrangement being such, that when the magnet is active or
energized the movement of the armature lever will cause the hook a to engage,the,
end of the long arm of the latch I, and thus lock it in position. Whenever the
magnet is de-energized or rendered inactive the armature O,. by reason of
the weight or equivalent retractile agency will be pulled back against a stop r
the hook n being thus removed from the, latch lever L, the clamp lever J. is;
released and the bar F rendered free to fall back out of engagement with the
bar B.
When the magnet P is energized the parts occupy the position shown. in. the
drawings the hook or detent n engaging the latch lever L.
Under these conditions if the rod H be pushed upward, then inasmuch, as the
levers J, L, are held up to their work by the hook or detent n, the bars F and B.
are held firmly in engagement, and consequently the signal may be inclined, or
lowered to safety position. If when this is accomplished, or at any time during
the movement, the magnet P should be demagnetized, the detent n will be at once.

page_text: removed from the latch lever L which together with the clamp lever J is then set
free, thus permitting the bar F to swing back out of engagement with the bar B,
the result of which would be that the signal would at once return to danger
position, and the bar F would be incapable of giving any motion to the bar B.
And so, with the parts in the position shown in Figure 1, if the magnet were
de-energized the signal could not be operated at all, because the detent would be
drawn back from the latch lever, and consequently there would be nothing at all to
hold the bar F up to its work. If under these conditions the rod H were raised,
the bar F would rise with it, but instead of lifting the bar B, it would simply push
to one side the clamp lever J.
1
It will be seen from the foregoing that the signal can in effect be governed
entirely from the magnet P, and that the signal is inevitably returned to or kept
at horizontal or danger position in case of breakage of wires, or any portion of the
circuit, failure of battery, or short-circuiting of the magnet from any cause-a
feature which is of manifest advantage in block systems where the magnet circuit
is formed in part of the track rails, as will be understood by reference to
Figures 2, 3, 4, 5.
In Figure 2, R R represents a section of one track of a double track railway
between two stations X, Y, the direction of traffic on which is indicated by the
arrow. The section R R is insulated at each end from the other part of the track
as indicated at i. The rails of the section R R form part of an electric circuit
which includes the key K and battery V at station Y, and magnet M at station X,
the circuit being completed by wires 1, 2, 3, 4, 5. This circuit is for convenience
termed the lock-operating circuit. There is also a second and local circuit at
station X, which includes the magnet P of the mechanism herein before described,
and its battery V'; and is completed through the armature lever of the magnet, M,
or through contacts controlled thereby. This circuit for, convenience, is termed the
lock circuit.
The parts are represented in their normal position, the signal standing at danger.
The part marked A is intended to conventionally represent the apparatus shewn in
Figure 1. Both circuits are shewn open-the lock operating circuit at the point
controlled by the key K at station Y, and the lock circuit at the point controlled
by the armature lever of magnet M, which is on its back stop.
Under these conditions to permit a train to enter the section R R the lever man
at station X must wire the man at station Y to connect him to his signal, which
the station Y man does by closing the lock operating circuit through his key K,
thereby energizing the magnet M, which by attracting its armature closes the local
lock circuit at station X. In this way the magnet P is energized and the brake
clamp in the signal operating mechanism at station X is consequently closed, thus
enabling the lever man at this station to shift his signal to safety. It is to be noted
however in this connection, that the ability of the operator at station Y to close
the circuit through the magnet M at station X would be curtailed by several
contingencies, as for example by a broken rail or wire, a defective battery, a bridge
swept away, a land slide, and last and most important by a section of a train or
even by a pair of connected wheels being left on the insulated portion R R of the
track. The men at both stations must therefore not only act in harmony but the
track, the circuits and the battery must be intact, the preceding train must have
entirely cleared the section R R and all conditions of safety must be fulfilled before
a following train can be admitted to the said section.
It is obvious that switches may be included in the rail portion of the lock
operating circuit so as to prevent the giving of a safety signal if a switch be
wrong.
As soon as the train passes the signal at X and enters upon the block section R, R,
the magnet M is cut out, (the current seeking the path of lower resistance offered
by the wheels aud axles of the cars) its armature lever drops back, and consequently
breaks the local lock circuit including the magnet P the effect of which is the
unlocking of the bars F, B, in the box A of Figure 1, and causing the released

page_text: signal to at once go automatically to danger. No two trains therefore can enter
the block section without the consent and aid of the lever men at both stations.
The signal is normally locked at danger, or what is equivalent the brake in the
signal operating mechanism is normally open, so that the signal cannot be moved
from the danger position until all safeguards are complied with.
There will be a corresponding arrangement for the section of the other track of
the double track, except of course for this section the apparatus shewn at station X
will be at station Y, and vice versa.
Substantially the same arrangement is applicable to a single track on which the
traffic is in both directions, only such modifications of the lock operating circuits
being required as to enable the same insulated track section to be used in
common for both lock operating circuits. This will be understood by reference
to Figure 3.
At each station there is a key K to control the lock operating circuit which
includes the magnet M at the other station. Each key K is between two contacts.
The upper contact, against which it normally rests, is in the lock operating circuit
controlled from the other station. The lower contact, from which it is normally
separated, is in its own lock operating circuit. Thus each key when out of action
forms part of the other circuit, and when closed to complete its own circuit,
necessarily opens the contact with the other.
The lock operating circuit from key K at station Y, is traced from that key as
follows:-
6, one rail of block section to station X, 7 K (of station X) 8, magnet M,
9, 10, other rail of block section back to station Y, 11, battery E (station Y)
12, lower contact of key K.
The corresponding circuit from key K at station X is traced from that key as
follows:-
7, one rail of insulated section to station Y, 6, K (of station Y) 13, magnet M,
14, 11, other rail of insulated section back to station X, 10 battery E (station X)
15, lower contact of key K.
Each magnet M controls at the station where it is located a lock circuit precisely
similar to that already described by reference to Figure 2.
All four circuits, the two lock operating circuits and the two local lock circuits
are normally open.
If the operator at station X for example close his key K, this will energize the
magnet M, at station Y, thus closing the local lock circuit through the magnet P
at that station and permitting the operator there to set his signal to safety and
admit a train from his end into the block section. The moment the train enters
the block section, the signal at Y, for reasons hereinbefore given automatically
goes to danger, and thereafter and until that train has passed out from the block
section, a safety signal cannot be given from either end.
It is impossible to give a safety signal from both ends simultaneously.
The arrangement illustrated in Figure 4 is one which can be advantageously
employed when for any reason it is deemed prudent to require the services of two
men to operate one signal, even at the same station, one to control the key K, the
other to operate the mechanical appliances for setting the signal. In view of what
has already been said, the arrangement will be understood from the figure without
further explanation. The man who handles the operating lever by which the
signal is set, can never put the signal to safety without the aid of the man at the
key K.
But the key man can always put the signal to or keep it at danger.
The apparatus as hereinbefore indicated can also be used in connection with any
of the home or distant signals of ordinary interlocking towers, and be made to act
as a "trip" to place such signals automatically to danger as soon as a train passes
Leyond the signal, but for this purpose to open the break in the signal operating
mechanism only momentarily, the brake theu automatically closing, so as to restore
the signal operating mechanism to operative condition. This is illustrated in
Figure 5, in which the signal is supposed to be operated from a tower, the traffic is

page_text: in the direction of the arrow, and the track has a short insulated section a little in
advance of the signal.
There is a local lock circut containing the magnet P for controlling the brake in
the signal operating mechanism, similar to the local circuit already described and
illustrated in Figures 2 and 3. There is also a second circuit, which like the lock
operating circuits already described is completed through the insulated track
section and includes the magnet M, by the armature of which magnet the circuit of
the magnet P is opened and closed, but which unlike those circuits, contains no key
and is always closed. Under these conditions the magnet M is normally energized,
the circuit of the magnet P is normally closed, and the signal operating mechanism
is normally in operative connection with the signal. But whenever a train passes
over the short insulated track section the magnet M is cut out or short circuited
and the signal goes to danger. The moment however the train passes the section,
the parts resume their normal condition and the signal can as before be operated in
the usual way from the tower.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The combination with a railway signal of signal operating mechanism composed
in part of two rods or slide bars capable of engaging with and being disengaged
from one another; a clamp through which the said bars pass and can move; means
for locking the clamp in its closed position; and an electro-magnet for controlling
the said locking means, substantially as and for the purposes herein before set forth.
2. The combination of a signal, a divided signal operating rod, a clamp for
holding together the two parts of the rod which pass through and move in the said
clamp, and an electro-magnetically operated detent for controlling the movable
member of the said clamp, substantially as and for the purposes hereinbefore set
forth.
3. The combination with a signal, of two toothed slide bars forming part of the
signal operating mechanism, the clamp lever J, the pivotted latch lever L for
locking and releasing the clamp lever, the detent n for locking and releasing the
latch lever, and the electro magnet and its armature lever O for controlling the
detent, substantially as and for the purposes hereinbefore set forth.
4. The combination of signal operating mechanism having at some point in it,
between the signal and the operating lever, a mechanical brake, means for closing
the brake, an electro-magnet controlling the said brake closing means: a lock
circuit including the said magnet; and a lock operating circuit, including an electro
magnet which controls contacts included in the lock circuit, substantially as and for
the purpose herein before set forth.
5. A railway electric block signalling system, comprising at one station a signal ;
signal operating mechanism having in it a mechanical brake; means for closing the
said brake, an electro-magnet for controlling the said brake closing means under
such an arrangement that the brake shall be open so long as the magnet is inactive ;
and a normally open lock circuit including the said magnet; in combination with
an insulated track section extending from that station to the next station; a
normally open lock operating circuit, formed in part by the track rails of the said
said section, and including at the one station the key by which it is closed and
opened, and at the other station where the signal to be operated is located an electro-
magnet controlling normally open contacts in the local lock circuit-the arrange-
ment being such that the local lock circuit at the one station, can be closed only
through the closure of the lock operating circuit at the other stations, substantially
as and for the purposes herein before set forth.
Dated this 8th day of November 1892