IMPROVEMENTS IN AUTOMATIC RAILWAY SIGNALS
Year: 1880

page_text: LETTERS PATENT to Lewis Vivian Loyd, Grenadier Guards, Guards' Club,
Pall Mall, in the County of Middlesex, for an Invention of "IMPROVEMENTS
IN AUTOMATIC RAILWAY SIGNALS."
PROVISIONAL SPECIFICATION left by the said Lewis Vivian Loyd at the
Office of the Commissioners of Patents on the 23rd June 1880.
LEWIS VIVIAN LOYD, Grenadier Guards, Guards' Club, Pall Mall, in the County
of Middlesex. "IMPROVEMENTS IN AUTOMATIC RAILWAY SIGNALS."
This Invention has for its object improvements in automatic railway signals.
At the present time it is usual to work railways upon what is known as the
block system, that is to say, the line is divided into sections of convenient length, and
as a train enters upon either of these sections a signal arm upon a post marking
the commencement of the section is raised to danger; the signal arm so raised is
not again lowered until the train has passed off the section at the other end.
It is now usual for such signals to be worked by signal men stationed at the
commencement of every section, and these men are in communication each one with
the next by electric telegraph.
Automatic mechanism to do this work has been proposed from time to time, but
no arrangement yet devised has offered such advantages as to lead to its adoption
by railway companies.
According to my Invention I provide upon the line of railway at the commence-
ment of each section a rail, in which there is a longitudinal slit or opening, and a
moveable treddle like blade is mounted in the opening in such manner that it can
rise above the surface of the rail. This blade is depressed by the passage of the
wheels of a train over it.
The blade carries a hood or cap overlapping the head of the rail so as to preclude
the possibility of dirt entering the opening in the rail and interfering with the free
working of the apparatus.
The treddle blade is supported upon the shorter arm of a bell crank lever which
projects beneath the rail. This lever can turn about an horizontal axis ; its longer

page_text: arm hangs below the axis, and is connected by a link with another bell crank lever
at the foot of the signal post. This second lover has its longer arm horizontal, or
nearly so, and a rod passing up from its end is jointed to a crank upon the same
axis with the signal arm.
Thus when the treddle blade is depressed by the wheels of a train the signal
arm on the adjacent post is thereby raised to danger.
In order to retain the signal arm when it has been raised by the passage of a
train over the treddle blade of the signal apparatus, a pawl lever is provided which
catches upon the end of the lower arm of the lever upon which the treddle blade is
supported.
The pawl lever has an horizontal axis, and the head or catch being at the lighter
end of the lever it rises in front of the lever arm, which it has to retain directly
that this has been moved back by the action of the wheels of the train upon the
treddle blade..
Thus the signal when raised is retained by the pawl, and it remains standing
at danger until the pawl is withdrawn. This is effected at the proper time by an
electro-magnet fixed above the pawl lever at its heavier end.
The electro-magnet is included in a battery circuit extending to the further end
of the section of the line of railway where the next signal apparatus is situate, and
the circuit is closed instantaneously as the wheels of the train pass over the treddle
blade of this apparatus.
Upon the closing of the circuit the electro-magnet attracts it armature, which is
fixed upon the pawl lever, and raises it, and the retaining head at the other end
of the pawl lever descends, thereby liberating the mechanism in connection with
the signal arm, and allowing the arm to fall by gravity to a position which
indicates that the section of the line of railway is clear, and that a train may safely
enter upon it.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Lewis Vivian Loyd in the Great Seal Patent Office on the 23rd
December 1880.
LEWIS VIVIAN LOYD, Grenadier Guards, Guards' Club, Pall Mall, in the County
of Middlesex. " IMPROVEMENTS IN AUTOMATIC RAILWAY SIGNALS."
This Invention has for its object improvements in automatic railway signals.
At the present time it is usual to work railways upon what is known as the
block system, that is to say, the line is divided into sections of convenient length,
and as a train enters upon either of these sections a signal arm upon a post marking
the commencement of the section is raised to danger, the signal arm so raised is not
again lowered until the train has passed off the section at the other end.
It is now usual for such signals to be worked by signal men stationed at the
commencement of every section, and these men are in communication each one with
the next by electric telegraph.
Automatic mechanism to do this work has been proposed from time to time, but
no arrangement yet devised has offered such advantages as to lead to its adoption
by railway companies.
According to my Invention I provide upon the line of railway at the commence-
ment of each section a rail in which there is a longitudinal slit or opening, and a
moveable treddle like blade is mounted in the opening in such manner that it can
rise above the surface of the rail. Or a lever at the side of the rail may be
employed. This blade is depressed. by the passage of the wheels of a train
over it.
The blade may carry a hood or cap overlapping the head of the rail so as to
preclude the possibility of dirt entering the opening in the rail and interfering with
the free working of the apparatus.
The treddle blade is supported upon the shorter arm of a bell crank lever which
projects beneath the rail. This lever can turn about an horizontal axis, its longer
arm hangs below the axis, and is connected by a link with another bell crank lever
at the foot of the signal post. This second lever has its longer arm horizontal, or .
nearly so, and a rod passing up from its end is jointed to a crank upon the same
axis with the signal arm.
Thus when the treddle blade is depressed by the wheels of a train the signal arm
on the adjacent post is thereby raised to danger.
In order to retain the signal arm when it has been raised by the passage of a
train over the treddle blade of the signal apparatus a pawl lever is provided which
catches upon the end of the lower arm of the lover upon which the treddle blade is
supported. The pawl lover has an horizontal axis, and the head or catch being at
the lighter end of the lever it rises in front of the lever arm, which it has to retain,
directly that this has been moved back by the action of the wheels of the train
upon the treddle blade.
Thus the signal when raised is retained by the pawl, and it remains standing at
danger until the pawl is withdrawn. This is effected at the proper time by an
electro magnet fixed above the pawl lever at its heavier end.
The electro magnet is included in a battery circuit extending to the further end
of the section of the line of railway where the next signal apparatus is situate and
the circuit is closed instantaneously as the wheels of the train pass over the treddle
blade of this apparatus.
Upon the closing of the circuit the electro magnet attracts its armature, which is
fixed upon the pawl lever, and raises it, and the retaining head at the other end of
the pawi lever descends, thereby liberating the mechanisin in connection with the
signal arm, and allowing the arm to fall by gravity to a position which indicates

page_text: DESCRIPTION OF THE DRAWINGS.
Figure 1 is a side elevation of my automatic signal gear, the rails of the line of
railway appearing in vertical transverse section; Figure 2 is an end elevation of the
same, the parts are in the same position as that in which they are represented in
Figure 1; Figure 3 is also an end elevation, but the parts are in the position they
assume when the electric circuit is momentarily completed to let the signal arm fall,
and to indicate that the line is clear; Figure 4 is a plan of the signal gear, in this
Figure the railway rails are not indicated. The electrical connections are represented
diagrammatically.
a and a aro the railway rails. In the rail a there is a longitudinal slit or
opening in which the moveable treadle like blade bis mounted. The blade 6 bas
a stem descending from it in the middle, and to this stem the cords c, c, are
attached, they are led over the pulleys d, d, and have weights e, connected at
their other ends. The weights serve to lift tho treddle blade b sufficiently to cause
it to stand somewhat above the level of the rail a. The blade bis bevilled at its
ends, so that the wheels of an approaching train may pass casily over it, and as
already stated the blade may be provided with a hood or cap overlapping the rail
to exclude dirt, but this hood or cap is not represented in the Drawings. The
blade is supported also by the shorter arm of the bell crank lever f, the
extremity of which passes through a hole in the stem b₁ of the blade. The lever f
partakes of the motion of the blade. The longer arm of the lever below its axis
is coupled by the link g with the lever h at the foot of the signal post k, and the
longer and nearly horizontal arm of the lever h is in turn coupled by means of the
rod with the crank or arin m on the axis of the signal arm n.
It will be seen
that from the connections described above it results that the signal arın is raised
whenever the treddle blade bis depressed by the wheels of a train passing over it.
When the signal arm is so raised it is retained and held by the pawl lever o, so that
it remains up at danger after the train has passed. The head of the pawl lever o
is inclined, and is of a hook like form, so that it yields to allow the lower end of
the lever fto pass it as the treddle blade descends, and then immediately the pawl
lever o catches the lever f and retains it, the tail of the pawl lever being heavier
than the head. is an electro-magnet, by which, at the proper time the signal
arm is set free and permitted to descend. The tail end of the lever o serves as the
armature of the electro-magnet, or it has an armature attached to it, and at the
proper time, when the train is passing another signal post, a battery circuit is
completed through this magnet. It then attracts its armature, causing the head of
the lever o to descend, freeing the lever f, and then by gravity the signal arm n falls,
and the weights e raise the treddle blade b again above the surface of the rail a
The electrical connections will be easily understood on reference to Figure 4; q
spring blade supported on an insulated post, so that its extremity is immediately
beneath the stein of the treddle blade b. The treddle blade is depressed to its
fullest extent only at the moment when the wheels of a train are upon it.
is a
It rises slightly immediately afterwards by the action of the weights, and before
it is caught by the pawl lever o, it passes again out of contact with the spring
blade g.
.
At the time when the treddle blade is in its lowest position, and at that instant
only the stem 61 of the treddle 6 comes into electrical contact with the spring
blade 9. The insulated spring blade is also electrically connected with one
extremity of the battery r, which consequently is put to earth when there is
contact between 9 and 6. The other extremity of the battery r is connected by

page_text: an insulated wire with the electro-magnet at a preceding signal post, and through
the coils of this magnet to earth. Thus when a train passes over the treddle blade b
the electro-magnet at a preceding station is rendered active and frees the signal
arm n, allowing it to fall to the position in which it indicates that the line is clear.
Similarly as the train passes each signal post it raises the signal arm to danger,
and at the same time completes an electric circuit momentarily, by which the
signal arm at the preceding station is released; represents the distant battery, in
the circuit of which the electro-magnet p is included; and q is the insulated
spring blade in electric connection with one pole of the battery.
Having thus described the nature of my said Invention, and the manner of
performing the same, I would direct especial attention to the fact that my arrange-
ment requires the battery circuits to be closed only momentarily as the trains pass
the signal posts, and hence there is not that serious expenditure of the battery
elements which is unavoidable when the battery circuits are normally closed, and
are only momentarily opened. Also I would remark that my mechanism is so
simple as to be little liable to become deranged, the use of springs being altogether
avoided, and any derangement of the mechanism which can possibly occur will not
givo riso to dangerous mistakes, for the result of a derangement would be to
maintain the signal at danger when it should be lowered. It is difficult to imagine
any derangement which could possibly have for its result that tho signal arm
should be down when it ought to be standing in the danger position.
What I claim is my improved arrangement of automatic railway signals,
substantially as herein described.
In witness whereof, I, the said Lewis Vivian Loyd, have hereunto set iny
hand and seal, this Twenty first day of December, in the year of our Lord
One thousand eight hundred and oighty.
LEWIS VIVIAN LOYD. (L.S.)