IMPROVEMENTS IN THE INTER- LOCKING OF RAILWAY TELEGRAPHIC BLOCK INSTRUMENTS, POINTS, AND ADDIRIES BAD ה זו DORDOGn
Year: 1881

page_text: LETTERS PATENT to Charles Hodgson, of Canterbury Road, Kilburn, in the
County of Middlesex, for an Invention of "IMPROVEMENTS IN THE INTER-
LOCKING OF RAILWAY TELEGRAPHIC BLOCK INSTRUMENTS, POINTS, AND
ADDIRIES BAD
ה זו
DORDOGn"
PROVISIONAL SPECIFICATION left by the said Charles Hodgson at the Office
of the Commissioners of Patents on the 2nd April 1881.
CHARLES HODGSON, of Canterbury Road, Kilburn, in the County of Middlesex.
"IMPROVEMENTS IN THE INTERLOCKING OF RAILWAY TELEGRAPHIC BLOCK
INSTRUMENTS, POINTS, AND SIGNALS, AND APPARATUS FOR THAT PURPOSE."
In the Specification of Letters Patent granted me on the 15th October 1879,
No. 4170, I described means of interlocking the telegraphic block instruments
employed on railways with points and signals. My present Invention relates to
improvements in the construction and arrangement of the apparatus described in
the said Specification, whereby I am enabled to effect interlocking of the
instruments at a signalling station with each other and with those at another
station, to provide against negligence in the use of these instruments, and to
transmit the necessary electrical currents for working them in both directions
along a single line wire.
In the Specification above referred to, I described a commutator that could be
made to act in either of two positions with suitable detents holding it in one or
other of these positions until it was released by the raising of a signal or the
passage of a train over a treadle. In one position in which the commutator is
employed to signal "line clear," it is of advantage that only one such signal should
be transmitted, otherwise more than one train could at the same time be admitted
on to the same section of the line. I therefore arrange a detent so that when the
plunger of the commutator in this position has been once pushed into signal
line clear" it cannot be again pushed in until the commutator has been moved to
its other position and there pushed in to signal "line blocked." This detent by
the latter movement of the plunger is moved into a position where it is held until
15

page_text: the commutator plunger is again pushed in for a "line clear" signal, whereupon it
engages with the plunger in its back stroke and prevents it from being pushed in
again while the commutator remains in the same position. As the plunger is
often employed not only to send a single signal, but also to transmit successive
currents for the purpose of causing a bell or other audible signal to sound a certain
number of times, it is of advantage to provide for this by bringing into action the
detent above mentioned electrically from the next station. For this purpose the
detent is set frce to act by the movement of the armature of an electro magnet
which is excited by a current from the next station transmitted to signal "train on
line." Thus, so long as there is no train on the section to which the instrument is
appropriated, the attendant can work the plunger when the commutator is in the
"line clear" position a number of times, but as soon as a train is permitted to
enter the section from the next station, the detent being set free to act engages
with the plunger and prevents its farther use while the commutator remains in that
position.
The detent, besides thus operating on the plunger, is so arranged as to make and
break electrical contacts in its two positions, thus preventing successive electrical
signals transmitted by the different instruments from interfering with one another
and enabling these to be sent by a single line wire. Usually there are at each
ordinary passing station two sets of block instruments, one appropriated to a
.section of the line, say, on the right, and the other to the section on the-left, each
instrument having its moveable commutator as described in the Specification above
referred to. When one of these commutators is moved to the "line clear" position
I cause it in passing to make an electrical contact whereby a current is transmitted
to an electro magnet in the other instrument. This electro magnet which is usually
employed to work a detent when a current is transmitted from a farther station,
may through negligence at that station have failed to operate, but the current
temporarily transmitted by the movement of the commutator, as stated above,
causes it to act, and the detent thereupon becomes engaged with the locking handle.
Thus the movement of the commutator for the purpose of signalling "line clear,"
say for a train from the left, locks the signalling handle for passing the train
onwards to the right until the detent is again disengaged by the signalman at the
next station on the right. In cases where two lines join two trains may approach
the junction at the same time, and if one of them should be permitted to pass
along the joint line the other should be detained until the former has passed out of
the first section of the joint line. In order to provide for this I arrange for each
of the two lines near the junction a starting signal, which as well as the points is
worked from an interlocking apparatus at the junction. Each of these signals
when it is lowered makes a temporary electrical contact by which a detent worked
by an electro magnet is permitted to act so as to prevent a second movement of
the locking handle for the purpose of lowering the other signal, not only until the
points have been shifted and locked, but also until the detent is again disengaged
by a current transmitted from the station at the end of the first section. Thus the
signal for the starting of the second train cannot be given until the first train has
arrived at the end of the section.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Hodgson in the Great Seal Patent Office on the
21st September 1881.
CHARLES HODGSON, of Canterbury Road, Kilburn, in the County of Middlesex.
"IMPROVEMENTS IN THE INTERLOCKING OF RAILWAY TELEGRAPHIC BLOCK
INSTRUMENTS, POINTS, AND SIGNALS, AND APPARATUS FOR THAT PURPOSE."
In the Specification of Letters Patent granted to me on the 15th October 1879,
No. 4170, I described means of interlocking the telegraphic block instruments
employed on railways with points and signals. My present Invention relates to
improvements in the construction and arrangement of the apparatus described in
the said Specification, whereby I am enabled to effect interlocking of the instruments
at a signalling station with each other, and with those at another station to
provide against negligence in the use of these instruments, and to transmit the
necessary electrical currents for working them in both directions along a single line
wire.
In the Specification above referred to, I described a commutator that could be
made to act in either of two positions with suitable detents holding it in one or other
of these positions, until it was released by the raising of a signal, or the passage of a
train over a treadle. In one position in which the commutator is employed; to
signal "line clear," it is of advantage that only one such signal should be transmitted,
otherwise more than one train could at the same time be admitted on to the same
section of the line. I therefore arrange a detent so that when the plunger of the
commutator in this position has been once pushed in to signal "line clear" it
cannot be again pushed in until the commutator has been moved to its other
position, and there pushed in to signal "line blocked." This detent by the latter
movement of the plunger is moved into a position, where it is held until the
commutator plunger is again pushed in for a "line clear" signal, whereupon it
engages with the plunger in its back stroke, and prevents it from being pushed in
again while the commutator remains in the same position. As the plunger is often
employed not only to send a single signal, but also to transmit successive currents
for the purpose of causing a bell or other audible signal to sound a certain number
of times, it is of advantage to provide for this by bringing into action the detent
above mentioned electrically from the next station. For this purpose the detent is
set free to act by the movement of the armature of an electro-magnet, which is
excited by a current from the next station transmitted to signal "train on line."
Thus, so long as there is no train on the section to which the instrument is
appropriated, the attendant can work the plunger when the commutator is in the
"line clear" position a number of times, but as soon as a train is permitted to
enter the section from the next station, the detent being set free to act, engages
with the plunger, and prevents its farther use while the commutator remains in
that position.
The detent, besides thus operating on the plunger, is so arranged as to make and
break electrical contacts in its two positions, thus preventing successive electrical
signals transmitted by the different instruments from interfering with one another,
and enabling these to be sent by a single line wire. Usually there are at each
ordinary passing station two sets of block instruments, one appropriated to a
section of the line, say, on the right, and the other to the section on the left, each
instrument having its moveable commutator, as described in the Specification above
referred to. When one of these commutators is moved to the "line clear" position
I cause it in passing to make an electrical contact, whereby a current is transmitted
to an electro-magnet in the other instrument. This electro-magnet, which is usually

page_text: employed to work a detent when a current is transmitted from a farther station,
may through negligence at that station have failed to operate, but the current
temporarily transmitted by the movement of the commutator, as stated above,
causes it to act, and the detent thereupon becomes engaged with the locking
handle. Thus the movement of the commutator for the purpose of signalling "line
clear," say, for a train from the left, locks the signalling handle for passing the
train onwards to the right, until the detent is again disengaged by the signalman
at the next station on the right. In cases where two lines join two trains may
approach the junction at the same time, and if one of them should be permitted to
pass along the joint line, the other should be detained until the former has passed
out of the first section of the joint line. In order to provide for this I arrange for
each of the two lines near the junction a starting signal, which, as well as the
points, is worked from an interlocking apparatus at the junction. Each of those
signals when it is lowered makes a temporary electrical contact, by which a detent
worked by an electro-magnet is permitted to act, so as to prevent a second move-
ment of the locking handle, for the purpose of lowering the other signal, not only
until the points have been shifted and locked, but also until the detent is again
disengaged by a current transmitted from the station at the end of the first section.
Thus the signal for the starting of the second train cannot be given until the first
train has arrived at the end of the section.
DESCRIPTION OF THE DRAWING.
Thus
Fig. 1 represents one of the levers for working a point or signal, and Fig. 2
represents part of a block instrument having in it the locking shaft S. On this
shaft is fixed a quadrant arc Q having a notch q. Immediately above is fixed an
electro-magnet M, the armature m of which is held up by attraction, while an
electric current passes through the coils of M, the quadrant Qand the shaft S being
in that case free to be moved. On the lever L, Fig. 1, is fixed a piece 7, which,
when the lever is moved over to the dotted position, passing a protuberance from
one of a pair of contact springs C, causes them to make contact, and so to short
circuit the electricity that was passing through the coils of M. By this short
circuiting the magnet M loses its attractive power on the armature m, which
whenever the notch a presents itself under it drops into that notch, and so prevents
the movement of the quadrant Q and shaft S in the direction of the arrow.
the movement of the lever L locks the locking shaft S, and causes all the levers
and instruments connected to S to be retained in the condition in which they were
before the lever L was moved. Such locking of the shaft S and of all connected with
it, instead of being effected by the movement of a lever may be effected by the
movement of the signalling commutator from one of its positions to the other, as
shewn in Fig. 3. In this case the plunger of the commutator when it is in the
position P can give certain signals, but in order to give other signals it has to be
moved to the position P¹. In passing from the one position to the other it acts on
the contact springs C, short circuiting the electric current in the same manner and
with the same effect as above described with reference to Figs. 1 and 2. When
the moveable commutator is in the position where it can be employed to signal
"line clear" it is generally desirable that its plunger should be prevented from
being more than once pressed in for the purpose of signalling, otherwise the
attendant might by negligence permit more than one train to occupy a section of
the line at one time. In order so to limit the signalling I apply at the back of the
signalling instrument a stop or detent mechanism, as shewn in Figs. 4, 5, 6, and 7,
Fig. 4 being a front view of that mechanism, Fig. 5 a plan, Fig. 6 a section on Z, Z,
and Fig. 7 a section on Y; Y, of Fig. 5. P is the commutator plunger in the
position for signalling "line clear," P¹ indicating its other position. A is a sliding
rod pressed forward by a spring and jointed at its end to a lever B. Another lever Č
has one of its arms jointed to one arm of a bell crank D, to the other arm of which
is jointed another sliding rod A': When the commutator is in the position P' it

page_text: may be pressed in to give a signal' more than once; but when it' is once pressed' in;
it, by pushing in the rod A¹ and so moving the bell crank D, raises the end'c'of
the lever C so that' this end rests on the top of the lever B. When the commu-
tator is moved to the position P it's plunger can be once pressed'in to'give the
signal line clear," but in this case by moving the rod A and so causing the
lever B to oscillate, the end c of the lever C is allowed to drop and to fall down'
behind the end of the rod' A so as to prevent it from being pushed in again. Thus
a second signal cannot be given until the commutator shall have been first moved'
back to the position P₁' and used there at least once for signalling.
In some cases it is desirable that when the signal line'clear" has been given
the signalling plunger should be pushed in repeatedly for the purpose of causing
a bell or other audible signal to be sounded so as to call the attention' of the'
attendant at another station, but that that attendant should have the power of
introducing a stop to prevent the plunger from being again pushed in. To effect
this I arrange mechanism, as shewn in Figs. 8 to 14 inclusive, these Figures also'
shewing an arrangement that may be adopted for the purpose of rendering' a single
line wire available for transmitting signals between two stations in both directions,
in such a manner that a second signal shall not interfere with the indication given
by a previous one. Fig. 8 is a front view, and Fig. 9' a' plan of this mechanism';"
Figs. 10, 11, and 12 are part transverse sections on the lines XX, W W, and'
VV of Fig 9 respectively; Fig. 13, which is a part section on UU of Fig. 8; and
Fig. 14, which is a plan, shew the mode of altering the contacts for signalling in'
both directions; S is the locking shaft with its quadrant Qand' stop q, which is'
caught by the hook h on the lever H, as described in the Specification of my previous"
Patent above, referred to; P and P¹ indicate the commutator plunger in its two
positions. As shewn in Figs: 8 and 9, the plunger in the position P can be pushed
in repeatedly. By the first act of pushing it in a horn p projecting from it presses*
against a spring detent E, moving it aside and so liberating a bent lever F, one
arm of which then falls and rests on the end of a lever G which is held up by
an armature K of an electro-magnet M. When the attendant at a distant station
transmits an electrical signal the magnet M having its coils in the circuit becomes
excited and attracts its spring armature K. The lever G being thus left without
support drops to the dotted position, and the arm f which rested on it also drops,
bringing the other arm of the lever F in front of a stud O between that stud and
the horn p. This interposition of the arm of F thereupon prevents the plunger P
from being again pushed in. When the commutator has been moved to the
position P¹ on pushing it in, while in that position another horn p¹ upon it acting
on one arm of a bent lever N raises the other arm N', which lifts the lever H,
releasing the hook from the stop q of the quadrant Q, and at the same time by
means of a stud h¹ on the prolongation of H lifting the arm f, so that the lever F
becomes engaged in a notch of the spring detent E whereby is is held up. The
hook lever H having thus been raised is held up by a spring catch h² engaging in
a notch at its end. When the commutator is again moved from the position P¹
to P a third horn p² on it moving along a protuberance on the lever H depresses
that lever again, causing its hook h to engage with the stop q. And when the
plunger in the position P is first pushed in, its horn p¹ acting on one arm of a bent
lever R causes the other arm to rise, lifting the lever G which passes the spring
armature K, but having passed it becomes again supported by it. When it is
desired to make a single line wire serve for signalling in both directions without
interference, I attach to the lever G four springs g, the upper ends of which are
interposed between four pairs of contacts t connected respectively to the line wire,
to earth, and to the opposite poles of the battery. Thus when the lever G is in
the raised position, as shewn in Fig. 8, to which position it had been raised by
pushing in the plunger at P, the contacts are such that the currents transmitted
along the line wire are of the same sign as that which had been transmitted by
pushing in the plunger at P, and consequently those currents even when trans-
mitted from other instruments cannot interfere with, so as to undo the actions
'

page_text: which had been produced by the use of the plunger at P. When on the other
hand the lever G having been released by the movement of the armature K has
dropped the contacts t are altered, so that when other instruments are employed
for signalling, currents are transmitted of opposite sign, that is to say, of the same
sign as that of the current transmitted by pushing in the plunger at P'. Thus
the actions resulting from pushing in the plunger are not interfered with by the
use of such other instruments, not only so, but if the attendant should have omitted
to push in the plunger in its position P', the same effect will be produced by the
use of the other instruments as if there had been no such omission.
Having thus described the nature of my Invention and in what manner the
same is to be performed, I claim in respect of apparatus for interlocking railway
telegraphic block instruments, points, and signals,―
First. The combination of a point or signal lever L or of a moveable commutator P
with a pair of contact springs C for the purpose of short circuiting the current for
the electro-magnet M so as to release its armature and permit it to stop the
locking shaft S, substantially as described with reference to Figs. 1, 2, and 3.
Second. The combination of a moveable commutator P with the sliding rods A
and A¹, and the levers B and C, and bellcrank D for the purpose of preventing the
repeated action of the commutator plunger P in one of its positions, substantially
as described with reference to Figs. 4, 5, 6, and 7.
The combination of the moveable commutator P, the detent E, the levers F, G,
H, N, and R, the electro-magnet M with spring armature K, and the stud O for
the purpose of permitting repeated use of the commutator plunger until it is
stopped by the transmission of an electric current, substantially as described with
reference to Figs. 8, 9, 10, 11, and 12.
Fourth. The combination of the moveable commutator P, the levers G, H, N,
and R, the electro-magnet M with armature K, and the contact springs g and
contacts t, for the purpose of rendering a single line wire available for signalling by
independent instruments without interference, substantially as described with
reference to Figs. 8, 9, 10, 11, 12, 13, and 14.
In witness whereof, I, the said Charles Hodgson, have hereunto set my hand
and seal, this Second day of July, in the year of our Lord One thousand
eight hundred and eighty one.
CHARLES HODGSON. (L.S.)