IMPROVEMENTS IN THE MEANS AND APPARATUS FOR WORKING RAILWAY SIGNALS.” APPARATUS FOR WORKING RAILWAY SIGNALS
Year: 1874

page_text: LETTERS PATENT to Robert Burn, junior, of Epsom, in the County of
Surrey, for the Invention of "IMPROVEMENTS IN THE MEANS AND
APPARATUS FOR WORKING RAILWAY SIGNALS.”
APPARATUS FOR WORKING RAILWAY SIGNALS."
PROVISIONAL SPECIFICATION left by the said Robert Burn at the
Office of the Commissioners of Patents, with his Petition, on the
4th September 1874.
I, ROBERT BURN, junior, of Epsom, in the County of Surrey, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
THE MEANS AND APPARATUS FOR WORKING RAILWAY SIGNALS," to be as
follows:-
This Invention relates to means of providing for the expansion and
contraction of the pulls employed to work railway signals, and of working
such signals to definite attitudes, either by themselves or in conjunction
with apparatus for giving audible signals to engine drivers.
For the purpose of providing for the expansion and contraction of the
signal pulls I mount. at some convenient point intermediate between the
-

page_text: signal lever and the signal a loaded lever, to one arm of which I attach
one portion of the pull extending to the signal lever, and to another arm
of which I also attach the other portion of the pull extending to the
signal itself. The arms to which I attach these portions of the pull are
of lengths proportional or nearly so to the lengths of the portions of the
pull respectively attached to them, so that in case of expansion or
contraction the lever moving on its fulcrum shall take up or give out
quantities proportional to the extent of such expansion or contraction in
each part of the pull, and thus maintain the effective length of the pull
uniform.
In order to make the required allowance for expansion or contraction
at the signal post itself I mount in vertically sliding or oscillating
bearings a pulley round which I pass the pull wire or a portion of chain
attached thereto carrying on the pull wire or chain to the arm of a
lever, to another arm of which lever I attach a certain extent of pull
wire, and I make these two arms of lengths proportional to the pull wire,
and to its extended part respectively. On the shaft of the pulley I fix a
crank arm, the crank pin of which enters a vertical slot in a plate
mounted like the blade of a parallel ruler, or bears against the face of a
bar so mounted, such plate or bar being connected to the signal rod.
By this arrangement, when the pull wires expand or contract the pulley
merely descends or rises without turning on its axis, but by a pull-in or
slack-out of the pull wire the pulley besides rising or descending, has also
to turn partly round on its axis, and the crank pin thereby is made to
move the plate or blade, and so to act upon the signal. In case the pull
wire should break, the pulley being then left free to turn, the signal is
set to or kept at danger by a counterbalance.
In the Specification of a Patent granted to me the said Robert Burn,
junior, and to Leopold- Joseph Green, on the 3rd March 1874, No. 774,
were described means of working a semaphore signal to three attitudes,
and of working in conjunction therewith a trigger for the purpose of
giving an audible signal to an engine driver. The modes above described
for the expansion or contraction of the signal pull are applicable to
signal apparatus of the kind described in the said Specification, and in
order to apply them in such cases in a more simple and effective manner
I arrange the connections between the pull wire, the signal, and the
trigger in the following manner :-Near the signal post I mount a
loaded lever, to which I attach the signal pull. This lever has a short

page_text: arm on which is mounted a pulley. A wire or chain passed round this
pulley is at one end attached to a bell crank on the signal post, and at
the other end to an arm on the rocking shaft of. the trigger, which is
conveniently mounted at some distance from the post. The lengths of
the lever arm to which the pull wire is attached, and of the arm on
which the pulley is mounted are so proportioned to the lengths of the
pull wire and of the wire or chain connected to the trigger respectively,
that when the pull wire of the signal and also that of the trigger expand
or contract the bell crank to which the latter is attached remains at rest,
as well as the trigger itself, but when the signal pull is drawn in or
slacked out the bell crank is then moved, so as to lower or raise the
semaphore arm, to which it is connected by a rod.
When, as described in the Specification above referred to, the pull
wire has been so far slacked out as to put the signal in the danger
attitude, a still farther slacking out by allowing the loaded lever to
descend farther causes the trigger to be raised so as to give the audible
signal on a locomotive in the manner set forth in the said Specification.
From this arrangement it will be seen that if the pull wire should break
the signal will be raised to danger, and also the trigger will be set so as
to give the audible signal.
I also make provision for raising the semaphore to danger in case the
pull connecting to the trigger should break, and this I effect as follows:―
The semaphore signal is so far counterbalanced that it will of itself take
the danger attitude but for a loaded lever which acts in a gab of its
rod, and which while it is engaged in this gab aids the descent of the
semaphore. Should the trigger pull break the semaphore suddenly
descends so far as to disengage the said lever from its gab, whereupon
the signal being released from the action of the lever is raised by its
counterbalance to the danger attitude.
30 SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Burn in the Great Seal Patent Office on
the 3rd March 1875.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourth day of September, in the
year of our Lord One thousand eight hundred and seventy-four, in
the thirty-eighth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Robert Burn, junior, Her
special license, that I, the said Robert Burn, junior, my executors,
administrators, and assigns, or such others as I, the said Robert
Burn, junior, 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 In-
vention for "IMPROVEMENTS IN THE MEANS AND APPARATUS FOR WORKING
RAILWAY SIGNALS," upon the condition (amongst others) that I, the said
Robert Burn, junior, 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 Robert Burn, junior, 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
accompanying Sheets of Drawings, and to the figures and letters marked
thereon, that is to say:-
This Invention relates to means of providing for the expansion and
contraction of the pulls employed to work railway signals, and of working
such signals to definite attitudes cither by themselves or in conjunction
with apparatus for giving audible signals to engine drivers.
For the purpose of providing for the expansion and contraction of the
signal pulls I mount at some convenient point, intermediate betwcen
the signal lever and the signal, a loaded lever, to one arm of which I
attach one portion of the pull extending to the signal lever, and to
another arm of which I also attach the other portion of the pull
extending to the signal itself. The arms to which I attach these
portions of the pull are of lengths proportional or nearly so to the

page_text: lengths of the portions of the pull respectively attached to them, so that
in case of expansion or contraction the lever moving on the fulcrum
shall take up or give out quantities proportional to the extent of such
expansion or contraction in each part of the pull, and thus maintain the
effective length of the pull. uniform.
In order to make the required allowance for expansion or contraction
at the signal post itself, I mount in vertically sliding or oscillating
bearings a pulley round which I pass the pull wire or a portion of chain
attached thereto, carrying on the pull wire or chain to the arm of a
lever, to another arm of which lever I attach a certain extent of pull
wire, and I make these two arms of lengths proportional to the pull
wire, and to its extended part respectively. On the shaft of the pulley.
I fix a crank arm, the crank pin of which enters a vertical slot in a plate
mounted like the blade of a parallel ruler, or bears against the face of a
bar so mounted, such plate or bar being connected to the signal rod.
By this arrangement, when the pull wires expand or contract the pulley'
merely descends or rises without turning on its axis, but by a pull-in or
slack-out of the pull wire the pulley besides rising or descending has
also to turn partly round on its axis, and the crank pin thereby is made
to move the plate or blade, and so to act upon the signal. In case the
pull wire should break, the pulley being then left free to turn, the signal
is set to or kept at "danger" by a counterbalance.
Instead of a pulley, as mentioned above, with a crank pin on one side
of it, a horizontal bar with an arm projecting from it vertically may be
employed.
When the main pull and the expansion wire expand or contract, the
bar on which they act merely descends or rises without affecting the
signal, but when the main pull is moved it is canted, so that its arm
acting on the parallel motion bar works the signal as above described.
In the Specification of a Patent granted to me the said Robert Burn,
junior, and to Leopold Joseph Green, on the 3rd March 1874, No. 774,
were described means of working a semaphore signal to three attitudes,
and of working in conjunction therewith a trigger for the purpose of
giving an audible signal to an engine driver. The modes above described
for the expansion or contraction of the signal pull are applicable to
signal apparatus of the kind described in the said Specification; and in
order to apply them in such cases in a more simple and effective manner

page_text: arrange the connections between the pull wire, the signal, and the
trigger in the following manner:-Near the signal post I mount a
loaded lever, to which I attach the signal pull. This lever has a short
arm on which is mounted a pulley. A wire or chain passed round this
pulley is at one end attached to a bell crank on the signal post, and at
the other end to an arm on the rocking shaft of the trigger, which is
conveniently mounted at some distance from the post. The lengths of
the lever arm to which the pull wire is attached, and of the arm on
which. the pulley is mounted are so proportioned to the lengths of the
pull wire and of the wire or chain connected to the trigger respectively,
that when the pull wire of the signal and also that of the trigger expand
or contract the bell crank to which the latter is attached remains at rest,
as well as the trigger itself, but when the signal pull is drawn in or
slacked out the bell crank is then moved so as to lower or raise the
semaphore arm, to which it is connected by a rod.
When, as described in the Specification above referred to, the pull
wire has been so far slacked out as to put the signal in the danger
attitude, a still farther slacking out by allowing the loaded lever to
descend farther causes the trigger to be raised, so as to give the audible
signal on a locomotive in the manner set forth in the said Specification.
From this arrangement it will be seen that if the pull wire should break
the signal will be raised to danger, and also the trigger will be set so as
to give the audible signal.
I also make provision for raising the semaphore to danger in case the
pull connecting to the trigger should break, and this I effect as follows:-
The semaphore signal is so far counterbalanced that it will of itself take
the danger attitude but for a loaded lever which acts in a gab of its rod,
and which while it is engaged in this gab aids the descent of the
semaphore. Should the trigger pull break, the semaphore suddenly
descends so far as to disengage the said lever from its gab, whereupon
the signal, being released from the action of the lever, is raised by its
counterbalance to the danger attitude.

page_text: my Invention. P is a piece of chain attached to the signal pull, which
passes over two pulleys p', p³, and is attached to a lever L; W is a picco
of pull wire, secured at one end at w, and at the other end attached to a
lever A, from which a chain a passes over a pulley a¹ to a weight a³,
having a stud on which the lever L is pivotted. The weight a² is guided
to slide vertically on a bar a³. The lever L is loaded by weights l, l.
On the lever L is an arm fitted with a roller 1, which bears against a
bar B mounted on radii b, b', like the blade of a parallel ruler. One or
the radii is the arm of a bell-crank lever, the other arm of which bª is
jointed to the signal rod S, which is connected to the semaphore arm in
the usual way, so that when the rod S descends the signal rises to its
"danger" attitude. The lever A is proportioned in the lengths of its
arms to the length of the pull P and of the expansion wire W, so that
when P and W both expand or both contract owing to changes of
temperature, the lever L simply descends or ascends without affecting
the position of the bar B; but when P is pulled by the lever at a
distance the lever L is raised upon its fulcrum a. The roller is thus.
pressed against the bar B so as to move it to the left, whereby the bell-.
crank arm is raised, and with it the rod S, allowing the semaphore to
descend. Should the pull P break the lever L descends without affecting
the semaphore, which is kept by its counterbalance to the "danger"
attitude. Again, should the wire W break the weight a² descends until
its stud escapes from the gab of the lever L, whereupon the said lever
rights itself, and the signal takes its "danger" attitude. As a further
precaution to secure this result the lower end of the bar B may be bent,
as indicated by the dotted lines ³, so that the weight a² when it
descends shall press ³ downwards, and thereby raise the signal to
"danger."
It is obvious that the two chains passing over the pullies a¹, p², Fig. 1,
instead of being attached, as shewn, to a lever L, might be carried
round the circumference of a pulley (of which L may represent the
diameter), the roller being in that case mounted on one side of the
pulley.
Fig. 4 represents a front, and Fig. 5 a side view of part of a signal.
post (Fig. 4 representing a plan thereof), shewing an arrangement of
the compensating apparatus in connection with the trigger for giving an
audible signal, a side view of which is shewn in Fig. 4ª, and a plan at
Fig. 6. In these Figures P is the signal pull worked by the lever at a

page_text: distance and attached to a lever L; W is the compensating wire attached
at one end to the trigger lever M, and at the other end brought round a
pulley w¹ and attached to the arm of a bell crank B; S is the signal rod
connected to the semaphore arm in the usual way, and jointed to a
sliding bar C presenting a gab, into which enters a pin on the bell
crank B. The lever L is pivotted on a bracket D; its long arm L'is
loaded by a weight, and its short arm L³ carries the pulley w¹. The
longer arm of the bell crank B is drawn upwards by a loaded lever E.
The lever M, which is loaded, is fixed upon a rocking shaft R, on which
is loosely mounted another lever N, the bosses of levers M and N being
clutched into one another in such a manner that M may descend
independently of N, but when M is raised it raises N with it. On the
shaft R is fixed a two-armed lever F under a plate T, hinged at one end
by the side of the rail. The arms L and L2 of the pull -lever are
proportioned to one another, as the length of the pull P is to half the
length of W. When therefore P and W expand or contract the position
of the bell crank B remains unaltered, and the signal is therefore not
affected. On drawing the pull P the bell crank B is drawn upwards by
the loaded lever E, and the semaphore arm descends, and again on
slacking out P the loaded arm L' draws down the bell crank B so as to
raise the signal to "danger," in which condition the bell crank B as
well as lever E is stopped. A further slack out of P, allowing L' to
descend still further, draws the wire W and lever M, whereby one arm
of the lever F is made to raise the hinged plate T. The plate T thus
being raised will act upon the alarum apparatus of a passing locomotive,
so as to give an audible signal in the manner described in the
Specification above referred to. If the pull P should break the signal
will stand at "danger," and the trigger plate T will be raised so far as a
stop T will permit. Again, should the wire W break the bell crank B
will be raised by the lever E until its pin escapes from the gab of the
rod C, whereupon the signal will be raised by its counterbalance to the
danger" attitude, and the lever M descending will by means of the
other arm of the lever F raise the trigger plate T.
66
A modified form of the compensating apparatus combined with the
trigger for giving an [audible signal is represented in Figures .7, 7ª, 8,
and 9, Fig. 7 being a front, and Fig. 8 a side view of part of the signal
post; Fig. 7 being a side view of the trigger apparatus, and Fig. 9 a plan
of the latter. In this case the pull P is carried over guide pullies and

page_text: attached to the sliding rod C, which is connected by a gab to a loaded
lever G, to which is jointed the signal rod S. One of the guide pullies p
is mounted on a counterweighted lever L, to which is attached, at l'a
wire connected by a bell crank w to the expansion wire W, which, latter
is connected to the trigger apparatus in the manner above described.
The lengths of the arms of L measured from its fulcrum to and p
respectively being proportioned to the lengths of W and of half P; the
expansion or contraction is provided for in the manner described above,
and the result of the fracture of either wire is to let the signal go to
"danger" and the trigger to rise, as already explained.
Having thus described the nature of my Invention, and in what
manner the same is to be performed, I hereby declare that I make no
general claim to the compensation for the expansion or contraction of a
railway signal pull by the use of a compensating wire, but in respect of
apparatus for working a railway signal in which such means of compen-
sation are employed, I claim,-
First. Arranging the pull and the compensating wire to act on the
signal motor by means of the lateral movement of a pin or roller, the
longitudinal movement of which resulting from expansion or contraction
is ineffective on the signal, substantially as herein described in reference
to Figs. 1, 2, and 3 of the accompanying Drawings.
Second. Connecting the compensating wire or the pull to the signal
motor after passing the one round a pulley mounted on the arm of a
lever worked by the other, the lever being so proportioned that the
expansion or contraction of the wire and pull produces a movement
which is ineffective on the signal motor, substantially as herein
described.]
Third. In apparatus of the kind referred to in the preceding claims,
providing the signal motor with a gab so arranged that in case of
fracture of the compensating wire the signal rod escapes, permitting the
signal to be moved by its counterweight to the "danger" attitude,
substantially as herein described.
Fourth. In apparatus of the kind above referred to, connecting the
compensating wire to a trigger by the side of the rail in such a manner
that when the signal pull is slacked out beyond the point necessary for
giving the danger signal, or when it breaks, or when the compensating

page_text: wire breaks, not only is the signal moved to "danger," but also the
trigger is raised for the purpose of acting on an audible alarum on a
passing locomotive, substantially as herein described.
In witness whereof, I, the said Robert Burn, junior, have hereunto
set my hand and scal, this Second day of March, in the year of 5
our Lord One thousand eight hundred and seventy-five.