IMPROVED APPARATUS FOR INTERLOCKING RAILROAD SWITCHES OR DRAW- BRIDGES AND SIGNALS
Year: 1875

page_text: LETTERS PATENT to Alexander Melville Olark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVED APPARATUS FOR INTERLOCKING RAILROAD SWITCHES OR DRAW-
BRIDGES AND SIGNALS."-A communication from abroad by David
Rousseau, of the City, County, and State of New York, United
States of America.
Sealed the 9th June 1876, and dated the 28th December 1875.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 28th December 1875.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVED APPARATUS FOR INTERLOCKING RAILROAD
SWITCHES OR DRAWBRIDGES AND SIGNALS," to be as follows:-
This Invention has for its object to produce a reliable switch and
drawbridge lock which can only be opened after a signal interposed

page_text: The Invention consists principally in locking the lever by which alone
the switch or drawbridge can be set by an armature lever into a closed
box or case, so that it cannot be withdrawn to set the switch or draw-
bridge unless the said armature lever is first attracted to its electro-
maguet.
The Invention consists, secondly, in placing said electro-magnet into
a circuit, which includes a distant signal, so that the circuit cannot
be closed unless said distant signal is first set at "danger."
The Invention further consists in placing the actuating mechanism of
said distant electric signal into a circuit leading to the box or case that
locks the afore-mentioned lever, so that said distant signal can only be
set at danger by pressing a key at such box or case; and when so set at
danger, the said signal is instrumental in closing the circuit through the
electro-magnet placed in such box or case, whereupon the armature is
attracted and the lever released. The attendant is now at liberty to
open the switch or drawbridge, and meanwhile any approaching train
will be duly warned by the danger signal.
The Invention also consists in leading the conductor through which
after the reclosing of the switch or drawbridge, the signal can be reset
to "safety "into said box or case, and in so interrupting it within said
box or case, that a current can only be sent through it after the said
lever has been reinserted and the armature lever dropped off the electro-
magnet, said lever reinserted and armature lever dropped off the magnet
serving to close the breaks or interruptions in the conductor; there-
fore, the distant signal must remain at "danger" until the attendant has
reset the switch or drawbridge and relocked the same; a reliable check
is thus placed on the operator, and at the same time the safety of trains
guaranteed. The operator cannot leave the switch or bridge neglectfully
open, as that would leave the signal at " danger" and cause speedily
detection of his negligence; nor can he after reclosing the switch or
bridge leave the operating lever unlocked, as that too would leave the
distant signal at "danger" and cause speedy detection of his conduct;

page_text: yet, after he has locked the lover he cannot unlock it from the armature
lever without first setting the signal at "danger."
The Invention also consists in further details of mechanism for
holding the armature to the electro-magnet, and for disengaging it, and
other features of improvement hereafter more fully described.
I have described the apparatus as connected with a switch, but it is
evident that the locking key or other device of a drawbridge may be
used with reference to the Invention in substantially the same relation
as the switch.
The switch rod is connected with the crank of a vertical shaft, so that
by turning said shaft the switch can be moved in line with the main or
with the branch line as may be desired. The shaft is almost entirely
enclosed within a box or case, to the interior of which access is not to
be had in ordinary cases, though it should have a locked door to allow
inspection of its contents. The shaft can only be turned to set the
switch by a jointed lever, which is rigidly attached to it outside of or
above the box or case, and whose handle part is hinged to the rigid part.
From the handle part of the lever projects a notched arm, which when
the switch is in line with the main line can be swung through a hole
into the interior of the box or case; when thus carried into the box the
arm arrives under an armature lever which drops into the notch of said
arm, and thereby locks it in the box or casc. The jointed lever is thus
locked, and with it the upright shaft and switch, and the latter cannot
be moved unless the armature is first raised off the notched arm and the
latter withdrawn from the box.
An electro-magnet is placed over the armature lever and joined by a
conductor to a battery, and by another conductor to the ground. A
break is made in the first conductor near a distant signal, and can only
be closed when said signal is turned to danger. The signal which I
intend to usually employ in conjunction with this apparatus is of sub-
stantially the same construction as is described in the Letters Patent,
No. 2740, granted me, and bearing date August 4th 1875. When the
signal is set at "safety," i.e., with its face parallel to the track, its
operative electro-magnet is in metallic connection with a conductor
which leads to the box or case before mentioned and joins the ground
wire. By pressure upon a key at the said box the ground wire can be
brought in contact with the conductor, thus establishing the circuit

page_text: through the clectro-magnet and battery, and if afterwards the signal
has been set to danger and has the break in the conductor, the con-
tinued pressure on the key at the box will cause a current to pass from
the battery over the wires to the electro-magnet of the box and thence
via the conductors to the ground. Upon being charged with electricity
the electro-magnet of the box attracts the armature and draws it off
the notched arm of the jointed lever before mentioned.
A weighted lever is also pivoted in the box, which is by its gravity
swung under the armature, as soon as it is attracted to its electro-
magnet, and holds said armature against said electro-magnet even
after the current by which the armature was attracted has been
interrupted.
The distant signal, when set at "danger," causes its electro-magnet to
come into metallic connection with a conductor which leads to the box,
and which has three breaks in said box, of which, one can be closed by
a key. The other two breaks or gaps are formed by two pairs of springs.
The first pair of springs are under the armature, and are brought in
contact with each other when said armature has dropped off its electro-
magnet, otherwise, that is, when the armature is raised, the springs are
apart. The other two springs are closed together by the notched
arm when the same is inserted into the box, otherwise they are
apart.
To the weighted lever above mentioned is pivoted a shorter weighted
lever, whose lower part bears against a pin that projects from the first-
mentioned lever or from the support thereof. When the notched arm is
introduced into the box, the weighted lever being beneath the armature,
a pin on the arm strikes the shorter weighted lever and vibrates it,
causing the same to strike the pin on the first-mentioned weighted lever,
and thereupon to swing the same away from under the armature, so that
the latter may drop into the notch of the arm.
The operation is as follows:-The switch being in line, the lever locked
by the armature and the distant signal set at safety, the operator if he
desires to set the switch in line with the branch, must first touch the
key at the box and establish a current through the electro-magnet of
the signal. This will cause the signal to be set at danger, and the con-
ductor to be perfected, and a circuit established through the electro-
-magnet in the box, the operator pressing on the key until the armature

page_text: is raised by the electro-magnet. The notched arm is now released and
can be withdrawn from the box, and the vertical shaft can be turned to
set the switch in the required manner. The signal meanwhile remains
at danger. When the switch is subsequently reset in line with the main
track the signal still remains at danger, until after the notched arm has
been reinserted into the box. This causes one of the breaks in the
conductor leading to the box to be closed; and as, by the introduction
of the notched arm, the armature is caused to drop off the electro-
magnet, the other break in the conductor is also closed, but the arm is
meanwhile also safely locked. A touch upon the key for closing the
break will now establish a current through the conductor and magnet
of the signal, and cause the signal to be reset at safety; thus it will be
seen that a complete check is obtained on the actions of the switch
tender, and at the same time absolute protection guaranteed the
trains.
The arrangement of the several parts herein-above specified may be
varied, especially the arrangements of conductors herein-above referred
to without departing from the spirit of the Invention. For example,
the conductor leading to the box may, if desired, be made without the
combination with a key, so that the signal will be reset at "safety" auto-
matically, when the notched lever arm is reinserted and the breaks in
the conductor may be omitted, or either of them, if desired.
Other variations, too manifold to be here separately pointed out, may
be made in the several parts referred to in the Specification, and yet the
double check on the attendant and train conductor be obtained, which
is indeed the principal feature of the Invention.
0
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent
Office on the 12th June 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of December, in the

page_text: year of our Lord One thousand eight hundred and seventy-five, in
the thirty-ninth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Alexander Melville Clark,
Her special license that I, the said Alexander Melville Clark, my
executors, administrators, and assigns, or such others as I, the said
Alexander Melville Clark, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time
and at all times thercafter 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 "IMPROVED APPARATUS FOR INTERLOCKING RAIL-
ROAD SWITCHES OR DRAWBRIDGES AND SIGNALS," a communication to mic
from abroad by David Rousseau, of the City, County, and State of
New York, United States of America, upon the condition (amongst
others) that I, the said Alexander Melville Clark, 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 Alexander Melville Clark, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascer-
tained in and by the following statement, reference being had to the
accompanying Sheet of Drawings, and to the letters and figures marked
thereon, that is to say :-
This Invention has for its object to produce a reliable switch and
drawbridge lock which can only be opened after a signal interposed
between a possibly approaching train and the switch or drawbridge has
been set to indicate "danger," and so that the switch or drawbridge
can only be opened after the lock has been affected in the manner above
indicated.
The Invention consists principally in locking the lever, by which
alone the switch or drawbridge can be set by an armature lever into
a closed box or case, so that it cannot be withdrawn to set the switch
or drawbridge, unless the said armature lever is first attracted to its
electro-magnet.

page_text: "
The Invention consists, secondly, in placing said electro-magnet into
a circuit which includes a distant signal, so that the circuit cannot be
closed unless said distant signal is first set at "danger."
The Invention further consists in placing the actuating mechanism
of said distant electric signal into a circuit leading to the box or case
that locks the afore-mentioned lever, so that said distant signal can only
be set at "danger" by pressing a key at such box or case; and when
so set at "danger" the said signal is instrumental in closing the circuit
through the electro-magnet placed in such box or case, whereupon the
armature is attracted and the lever released. The attendant is now
at liberty to open the switch or drawbridge, and meanwhile any
approaching train will be duly warned by the danger signal.
The Invention also consists in leading the conductor through which,
after the reclosing of the switch or drawbridge, the signal can be reset to
safety "into said box or case, and in so interrupting it within said box
or case, that a current can only be sent through it after the said lever has
been reinserted and the armature lever dropped off the electro-magnet,
said lever reinserted and armature lever dropped off the magnet serving
to close the breaks or interruptions in the conductor. Therefore the
distant signal must remain at danger until the attendant has reset the
switch or drawbridge and relocked the same. A reliable check is thus
placed on the operator and at the same time the safety of trains
guaranteed. The operator cannot leave the switch or bridge neglectfully
open as that would leave the signal at danger, and cause speedy detec-
tion of his negligence. Nor can he, after reclosing the switch or bridge,
leave the operating lever unlocked, as that too would leave the distant
signal at danger, and cause speedy detection of his conduct. Yet after
he has locked the lever he cannot unlock it from the armature lever
without first setting the signal at danger.
The Invention also consists in further details of mechanism for
holding the armature to the clectro-magnet and for disengaging it, and
other features of improvement herein-after fully described.
Figure 1 in the accompanying Drawing is a diagram, showing the
relative position of the apparatus to the electric conductors and signal
employed in conjunction with the same.
Figure 2 is a vertical transverse section of the box or case containing
the locking mechanism, showing the lock opened, and Figure 3 is a similar

page_text: view of the same, showing it closed; Figure 4 is an inner face view OL
the same.
Figure 5 is a detail side view of the double balanced lever used for
holding the armature clevated; and Figure 6 is an edge view of the
same.
Similar letters of reference indicate corresponding parts in all the
Figures.
A represents the main track; B, the branch track; and C, the con-
necting switch of a railroad. The Drawing shows the apparatus con-
nected with a switch, but it is evident that the locking key or other device
of a drawbridge may be used with reference to the Invention, in sub-
stantially the same relation as the switch.
D is the switch rod connected with the crank a of a shaft E, so that
by turning said shaft the switch can be moved in line with the main or
with the branch line, as may be desired. The shaft E is almost entirely
closed within a box or case F, to the interior of which access is not
to be had in ordinary cases, though it should have a locked door to
allow inspection of its contents, and of repairs. The shaft E can only
be turned to set the switch by a jointed lever G, which is rigidly
attached to it outside of or above the box or case, as shown, and whose
handle part bis hinged to the rigid part. From the handle part of
the lever G projects a notched arm d, which when the switch is in lino
with the main line, as in Figure I, can bo swung through a hole into
the interior of the box or case F, as clearly shown in Figure 3. When
thus carried into the box the arm & arrives under an armature lever H,
which drops into the notch of said arm, as in Figure 3, and thereby
locks it in the box or case. The jointed lever G is thus locked, and
with it the shaft E and switch C, and the latter cannot be moved unless
the armature H is first raised off the notched arm d, and the latter
withdrawn from the box F, as in Figure 2.
I is an electro-magnet placed over the armature lever H, and joined
by a conductor e, f, to a battery J, and by a conductor g, h, to the
ground. A break in the conductor e, f, is near'a distant signal K, and
can only be closed when said signal is turned to danger. The signal
which I intend to usually employ in conjunction with this apparatus is
of substantially the same construction, as is described in the Letters
Patent, No. 2740, granted to William Clark, and bearing date August
4th, 1875, and is in Figure 1 of the Drawing, represented to bo

page_text: set at "safety," i.c., with its face parallel to the track. In this position
its operative electro-magnet i is in metallic connection with a con-
ductor j, which leads to the box F and joins the wire g. By pressure.
upon a key at the box F, the ground wire h can be brought in contact
with the conductor j; thus establishing the circuit through the electro-
magnet i and battery J; and if afterwards the signal has been set to
danger, and has closed the break in the conductor e, f, the continued
pressure on the key / will cause a current to pass from the battery over
the wires f, e, to the electro-magnet I of the box F, and thence via the
conductors g, h, to the ground. Upon being charged with electricity
the electro-magnet I attracts the armature H and draws it off the arm d
of the lever G.
A weighted lever L pivoted in the box F is by its gravity swung
under the armature H as soon as it is attracted to its electro-magnet I,
and holds said armature against said electro-magnet, even after the
current by which the armature was attracted has been interrupted.
The signal K when set at danger causes its electro-magnet i to comc
into metallic connection with a conductor m which leads to the box F',
and which has three breaks in said box of which one can be closed by a
key n. The other two breaks or gaps are formed by two pairs of
springs o, o, and p, p. The springs o, o, are under the armature H and
are brought in contact with each other when said armature has dropped
off its electro-magnet I as in Figure 3. Otherwise, that is, when the
armature H is raised the springs o, o, are apart, as in Figure 2. The
other two springs p, p, are closed together by the arm d, when the same
is inserted into the box F as in Figure 3, otherwise they are apart as in
Figure 2.
To the weighted lever L is pivoted a shorter weighted lever M, as in
Figures 5 and 6, whose lower part bears against a pin that projects
from the lever L or from the support thereof. When the arm dis
introduced into the box F, the lever L being beneath the armature H,
a pins on the arm & strikes the lever M and vibrates it, causing the
same to strike the pin " and thereupon to swing the lever L away from
under the armature, so that the latter may drop into the notch of the
arm & as in Figure 3.
The operation is as follows:-The switch being in line, the lever G
locked by the armature H, and the signal K set at safety, all as in
Figure 1, the operator if he desires to set the switch in line with the

page_text: branch line must first touch the key
and establish a current through
the electro-magnet i of the signal. This will cause the signal to be set
at danger and the conductor e, f, to be perfected, and a circuit established
through the electro-magnet I in the box, the operator pressing on the
key until the armature H is raised by the electro-magnet. The arm d.
is now released and can be withdrawn from the box, and the shaft E can
be turned to set the switch in the required manner. The signal mean-
while remains at danger; when the switch is subsequently reset in line
with the main line the signal still remains at danger until after the
arm & has been re-inserted into the box. This causes the break p, p, in
the conductor m to be closed, and as by the introduction of the arm d
the armature H is caused to drop off the electro-magnet I, the break o, o,
in the conductor m is also closed; but the arm d is meanwhile also
safely locked. A touch upon the key n will now establish a current
through the conductor m and magnet i, and cause the signal to be reset
at safety. Thus it will be seen that a complete check is obtained on the
action of the switch tender and at the same time absolute protection
guaranteed the trains.
The arrangement of the several parts herein-above specified may be
varied, especially the arrangement of conductors herein-above referred to
without departing from the spirit of the Invention. The conductor m
may if desired be made without the combination with a key n, so that
the signal will be reset at safety automatically, when the lever arm & is
re-inserted, and the breaks o, p, in the conductor m may be omitted, or
either of them, if desired.
Other variations too manifold to be here separately pointed out may
be made in the several parts referred to in the Specification, and yet
the double check on the attendant and train conductor obtained which
is indeed the principal feature of the Invention.
Having described the nature of the said Invention and the manner of
performing the same, I declare that what I claim as the Invention to bc
protected by the herein-before in part recited Letters Patent is,-
1st. The switch lever G combined with the box F and with the
armature therein to be locked by said armature, substantially as
specified.
2nd. The combination of the electro-magnet I within the switch box F
with the distant signal K and the uniting conductors, in such manner

page_text: that the current through the magnet I is established when said signal is
set to danger as specified.
3rd. The combination of the distant signal K with the conductor j,
switch box F, and key l, all arranged so that the signal is set at danger
by pressing the key at the switch box, substantially as specified.
4th. The combination of the lever G, electro-magnet I, and locking
armature H, with the box F, conductors j, f, e, and signal K, sub-
stantially as herein shown and described.
5th. The combination of the signal K. with the releasing conductor m,
which has one or more breaks o, p, and with the switch box F within
which said breaks are concealed, substantially as herein shown and
described.
6th. The combination of the armature H with the lever arm d and
with the conductor m having the break o, said break to be closed when
the armature locks the arm a, substantially as specified.
7th. The combination of the lever arm & with the receiving box F and
with the conductor m having the break p, substantially as described,
said break to be closed when the arm & is inserted within the box, sub-
stantially as specified.
Sth. The combination of the balanced lever L with the armature H,
and with the switch lever which is locked by said armature, substantially
as specified.
9th. The lever M combined with the lever L and with the arm d of
the switch lever, substantially as specified.
10th. The combination of a railroad switch or bridge lock with a
distant signal, substantially as described, and operating so that the
signal shows danger when the switch or bridge lock is open, and that
the switch or bridge lock is closed when the signal shows safety as
specified.
In witness whereof, I, the said Alexander Melville Clark, have here-
unto set my hand and seal, this Twelfth day of June, in the
year of our Lord One thousand eight hundred and seventy-six.
A M
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