IMPROVEMENTS IN RAILWAY SIGNAL APPARATUS
Year: 1872

page_text: LETTERS PATENT to John Clayton Mewburn, of 169, Fleet Street, in
the City of London, Patent Agent and Consulting Engineer, for
the Invention of "IMPROVEMENTS IN RAILWAY SIGNAL APPARATUS." -A
PROVISIONAL SPECIFICATION left by the said John Clayton Mewburn
at the Office of the Commissioners of Patents, with his Petition,
on the 26th October 1872.
I, JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of
London, Patent Agent and Consulting Engineer, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN RAILWAY SIGNAL
APPARATUS," to be as follows:-
This Invention of improvements in railway signal apparatus has
reference to the means of working the signal discs, the object of which
is to prevent collisions, and to indicate to the driver of a train that the
line is not clear. The apparatus hitherto employed are not perfect,
because being worked by a signalman they depend more or less upon

page_text: proper attention to his duty. Hitherto neglect on his part might cause
the disc to indicate incorrectly that the line was clear, but with
apparatus constructed according to the present Invention a similar
neglect would simply have the effect of needlessly stopping a train,
because the disc having been moved into the "danger" position by the
passing of a preceding train has not afterwards been moved back to
"all clear" by the signalman. There is thus a certainty of the line
being signalled "danger" every time it is necessary, because the disc
cannot return to the "all clear" position except by being worked by
hand.
The leading features of this Invention are first, that a train or engine
gives a signal of itself by the simple fact of passing the disc, by an
electric sounding apparatus; and secondly, that the disc in moving to
the danger position performs its quarter revolution without moving any
of the parts which connect the disc with the signal box.
The train in passing bears upon a pedal, which by a horizontal
rod raises an arm on which one end of a lever rests. This lever is jointed
to a cross piece fixed to the post of the disc. A pulley having two
grooves on its periphery is loose on this post. A chain connects this
pulley with the signalman's lever, and another chain puts the pulley in
connection with a counterweight. Above the pulley is a sloping or
inclined abutment.
The action is as follows:-Supposing the disc to be in the "all clear
position, a counterweight which is connected by a chain to another
pulley on the disc post tends to cause the disc to turn, but the abutment
above named prevents the lever effecting the quarter revolution
necessary, it therefore remains at "all clear." As soon as a train or
engine passes the pedal raises the arm before named together with the
lever. In this position the lever is no longer held by the abutment so
that the disc pulled by the weight makes a quarter turn. The first
wheel of the train having been enabled alone to produce the movement
of the disc to "danger" it is necessary to prevent the following wheels
bearing uselessly on the pedal; for this purpose there is keyed on the
disc post below the double groove pulley a sector surmounted by an
inclined plane. At the same time that the disc moves to "danger" the
inclined plane raises the arm before named, and consequently keeps the
pedal lowered from the rails, and this will last as long as the disc

page_text: remains at danger; thus none of the wheels after the first will act on
the pedal. Stops limit the play of the disc. When the lever has
been raised it leaves the arm which lifted it and falls upon the flat
part of the pulley.
Now to return the disc to the "all clear" position, there are two
movements to be given to the signalman's lever. This lever is in con-
nection with the disc by one of the chains on the double grooved pulley,
and a counterweight is connected by the other chain to this pulley,
having for object to keep the first chain taut. By a first movement of
the signalman's lever towards the disc the first chain is freed allowing
the counterweight to give a quarter turn to the double grooved pulley,
and at the same time the inclined abutment returns behind the other
lever into its normal position. By a second movement of the signal-
man's lever contrary to the first, the pulley returns the other lever and
the disc to their original position, as well as the arm and the pedal.
stops limit the play of the pulley.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Jolin Clayton Mewburn in the Great Seal Patent
Office on the 24th April 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
CLAYTON MEWBURN, of 169, Fleet Street, in the City of London,
Patent Agent and Consulting Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria by Her
Letters Patent, bearing date the Twenty-sixth day of October, in the
year of our Lord One thousand eight hundred and seventy-two, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said John Clayton Mewburn, Her
special licence that I, the said John Clayton Mewburn, my executors,
administrators, and assigns, or such others as I, the said John Clayton
Mewburn, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN RAILWAY SIGNAL APPARATUS," (a communication from

page_text: abroad by Victor Moreau, of Seclin, France) upon the condition
(amongst others) that I, the said John Clayton Mewburn, my executors
or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was
to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said John Clayton Mewburn, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by
the following statement thereof, reference being had to the accom-
panying Drawings, that is to say:→
This Invention of improvements in railway signal apparatus has
reference to the means of working the signal discs, the object of which
is to prevent collisions, and to indicate to the driver of a train that the
line is not clear. The apparatus hitherto employed are not perfect
because being worked by a signalman they depend more or less upon
proper attention to his duty. Hitherto neglect on his part might cause
the disc to indicate incorrectly that the line was clear, but with
apparatus constructed according to the present Invention, a similar
neglect would simply have the effect of needlessly stopping a train,
because the disc having been moved into the "danger" position by the
passing of a preceding train has not afterwards been moved back to
“all clear" by the signalman. There is thus a certainty of the line
being signalled "danger" every time it is necessary, because the disc
cannot return to the "all clear" position except by being worked by
hand.
The leading features of this Invention are first that a train or engine
gives a signal of itself by the simple fact of passing the disc by an
electric sounding apparatus; and secondly, that the disc in moving to
the danger position performs its quarter revolution without moving any
of the parts which connect the disc with the signal box.
The apparatus is represented in the annexed Drawings, Figure 1
being an elevation, and Figure 2 a plan. The train in passing bears.
upon a pedal B, which by a horizontal rod a on which it is fixed raises
an arm or lever T on which one end of a lever L rests; this lever Lis

page_text: jointed to a cross piece fixed to the post A of the disc. A pulley M
having two grooves g, g¹, on its periphery is loose on this post. A
chain C¹ connects this pulley with the signalman's lever, and another
chain C puts the pulley in connection with a counterweight q. Above.
the pulley is a sloping or inclined abutment d.
The action is as follows:-Supposing the disc to be in the "all clear"
position, a counterweight p which is connected by a chain C to another
pulley F on the disc. post tends to cause the disc to turn, but the
abutment d above named prevents the lever L effecting the quarter.
revolution necessary, it therefore remains at "all clear." As soon as a
train or engine passes, the pedal B being forced down to B¹, raises the
arm or lever T to the position T, and the lever L to L', Figure 1. In
this position the lever L is no longer held by the abutment d, so that the
disc pulled by the weight p makes a quarter turn, and the lever L
comes to the position L', Figure 2. The first wheel of the train having
been enabled alone to produce the movement of the disc to "danger,"
it is necessary to prevent the following wheels bearing uselessly on the
pedal; for this purpose there is keyed on the disc post below the double
grooved pulley a sector or quadrant S, surmounted by an inclined
plane m, n. At the same time that the disc moves to " danger," the
inclined plane m, n, raises the arm or lever T and consequently keeps
the pedal B at B' lowered from the rails, and this will last as long as the
disc remains at danger. Thus none of the wheels after the first will
act on the pedal. When the lever L has been raised it leaves the arm T
which lifted it and falls upon the flat part of the pulley M.
Now to return the disc to the "all clear" position, there are two
movements to be given to the signalman's lever. This lever is in con-
nection with the disc by the chain C¹ on the double grooved pulley, and
a counterweight q is connected by the other chain C" to this pulley,
having for object to keep the first chain taut. By a first movement of the
signalman's lever towards the disc the first chain O' is freed allowing the
counterweight q to give a quarter turn to the double grooved pulley M,
and at the same time the inclined abutment d returns behind the
lever L into its normal position. By a second movement of the signal-
man's lever contrary to the first, the pulley M by means of the
abutment & returns the lever L and the disc to their original 'position
as well as the arm and the pedal. Stops I, I, and O, O, limit the play
of the pulley and of the sector S; R is a guide in which the arm or

page_text: lever. T works; this guide carries india-rubber pads h, h, which limit
the movements of the said arm or lever and lessen the jar or concussion
at each movement.
And having now described the nature of the said Invention, and in
what manner the same is to be performed, I declare that I claim,
constructing railway signal apparatus substantially as herein-before
described and represented in the accompanying Drawings.
In witness whereof, I, the said John Clayton Mewburn, have
hereunto set my hand and seal, this Twenty-fourth day of April
One thousand eight hundred and seventy-three.