IMPROVEMENTS IN MEANS AND APPARATUS WHEREBY THE BLOCK AND INTERLOCKING SYSTEMS OF RAILWAYS ARE COMBINED SO AS TO EFFECT RECIPROCAL LOCKING OR CONTROL OF POINTS AND SIGNALS AND TELEGRAPHIC BLOCK INSTRUMENTS "
Year: 1877

page_text: LETTERS PATENT to Charles Hodgson, of Canterbury Road, Kilburn, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN MEANS AND
APPARATUS WHEREBY THE BLOCK AND INTERLOCKING SYSTEMS OF RAILWAYS
ARE COMBINED SO AS TO EFFECT RECIPROCAL LOCKING OR CONTROL OF POINTS
AND SIGNALS AND TELEGRAPHIC BLOCK INSTRUMENTS
"
PROVISIONAL SPECIFICATION left by the said Charles Hodgson at the
Office of the Commissioners of Patents on the 31st January 1877.
CHARLES HODGSON, of Canterbury Road, Kilburn, in the County of Middlesex.
'IMPROVEMENTS IN MEANS AND APPARATUS WHEREBY THE BLOCK AND INTER-
LOCKING SYSTEMS OF RAILWAYS ARE COMBINED SO AS TO EFFECT RECIPROCAL
LOCKING OR CONTROL OF POINTS AND SIGNALS AND TELEGRAPHIC BLOCK INSTRU-
MENTS."
My Invention relates to means and apparatus for combining instruments such as
are employed for block signalling on railways with apparatus for working the
points and signals so as to interlock the one with the other for the purpose of
insuring safety of traffic. On railways worked by the block system, serious
accidents have occurred in consequence of the error, omission, or misapprehension
of telegraphic communications from one station to another.
The object of my Invention is to prevent such mistakes, and I effect this by
making the telegraphic communication depend upon the condition of the point and
signal apparatus, and making the condition of that apparatus depend upon the
telegraphic communication.
In order that the nature of my Invention may be readily understood, I will
assume that there are three successive stations, A, B, and C, on a line of railway,
and that at each of those stations there is an ordinary frame of point and signal
levers interlocked in any known manner, and also electrical block signalling instru-
ments by which each signalman can communicate to the next. I arrange those
instruments in proximity to the lever frame, and to each instrument I fit a spindle
or sliding rod which can be moved by hand so as to make or break contact with
the line wire. This spindle or rod is connected in each case to a sliding bar or

page_text: rocking shaft which extends along the row of point and signal levers. On this bar
or shaft I fix in suitable positions stops or arms so arranged that when it is moved
by the spindle or rod aforesaid, levers are thereby locked or unlocked as may be
required, and that when levers are moved they obstruct or release the sliding bar
and thereby lock or unlock the spindle or rod connected to it. Instead of applying
this interlocking directly to the levers, I prefer to apply it to their spring catches or
the equivalent mechanisms employed to hold the levers at each end of their stroke,
as thereby the locking is effected before the movement of a lever, and the unlocking
is not effected till after the completion of its stroke. Assuming now that A has
signalled to B that a train is about to enter the section A, B, then B put his point
and signal levers right for the reception of the train, and thus unlocks his electrical
instrument, whereby he signals back to A "line clear," and by so signalling he
locks his levers in the right position for the passage of the train. It is obvious
that similar apparatus. and modes of operating are applicable in cases of a more
complex character than that which has been given above by way of illustration ;
also that the succession of operations may be varied to suit different systems of
working traffic.
I have thus described the means by which the signalling instruments and point
and signal levers at one station are interlocked with each other; I will now describe
additional appliances whereby the signalman at one station can control operations
of the signalman at another station. For this purpose, at the one station I apply
to the spindle or sliding rod of the block signalling instrument a trigger or detent
connected to the armature of an electro-magnet, the coil of which is in circuit with
the line wire and indicating instrument from the other station. When this indi-
cating instrument gives the proper signal, the electro-magnet connected to it acting
on the armature causes the detent or trigger to engage with or disengage from a
stop on the spindle or rod so as to prevent it from being moved or to permit it to
be moved as the case inay be.
In order to explain the application of this part of my Invention, I will recur to
the case already given in illustration of the preceding part. I have there said that
B, having put his levers right, signals back to A "line clear;" by this operation he
can, by the means last described, release the spindle or rod of A's signalling instru-
ment, thereby permitting A to work it so as to lock or unlock his own levers.
I have above described my Invention as applied in connection with levers for
working points and signals, as these are the instruments most commonly used for
for that purpose. It is however evident that by suitable modifications of the
mechanism it is equally applicable in connection with instruments of other kinds
that may be employed for working points and signals.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Hodgson in the Great Seal Patent Office on the 26th June
1877.
CHARLES HODGSON, of Canterbury Road, Kilburn, in the County of Middlesex.
"IMPROVEMENTS IN MEANS AND APPARATUS WHEREBY THE BLOCK AND INTER-
LOCKING SYSTEMS OF RAILWAYS ARE COMBINED SO AS TO EFFECT RECIPROCAL
LOCKING OR CONTROL OF POINTS AND SIGNALS AND Telegraphic BLOCK INSTRU-
MENTS.
My Invention relates to means and apparatus for combining instruments, such as
- are employed for block signalling on railways, with apparatus for working the points
and signals so as. to interlock the one with the other for the purpose of ensuring
safety of traffic. On railways worked on the block systein serious accidents have
occurred in consequence of the error, omission, or misapprehension of telegraphic
communications from one station to another,

page_text: The object of my Invention is to prevent such mistakes, and I effect this by
making the telegraphic communication depend upon the condition of the point
and signal apparatus, and making the condition of that apparatus depend upon the
telegraphic communication.
In order that the nature of my Invention may be readily understood I will
assume that there are three successive stations, A, B, and C, on a line of railway,
and that at each of those stations there is an ordinary frame of point and signal
levers interlocked in any known manner, and also electrical block signalling instru-
ments by which each signalman can communicate to the next; I arrange those in-
struments in proximity to the lever frame, and to each instrument I fit a spindle or
sliding rod, which can be moved by hand so as to make or break contact with the
line wire; this spindle or rod is connected in each case to a slding bar or rocking
shaft, which extends along the row of point and signal levers; on this bar or shaft
I fix in suitable positions stops or arms so arranged that when it is moved by the
spindle or rod aforesaid, levers are thereby locked or unlocked as may be required,
and that when levers are moved they obstruct or release the sliding bar or rocking
shaft, and thereby lock or unlock the spindle or rod connected to it. Instead of
applying this interlocking directly to the levers, I prefer to apply it to their spring
catches, or the equivalent mechanisms employed to hold the levers at each end of
their stroke, as thereby the locking is effected before the movement of a lever, and
the unlocking is not effected till after the completion of its stroke. Assuming now
that A has signalled to B that a train is about to enter the section A, B, then B
puts his point and signal levers right for the reception of the train, and thus unlocks
his electrical instrument, whereby he signals back to A line clear," and by so sig-
nalling he locks his levers in the right position for the passage of the train. It is
obvious that similar apparatus and modes of operating are applicable in cases of a
more complex character than that which has been given above by way of illustra-
tion; also that the succession of operations may be varied to suit different systems
of working traffic.
"
I have thus described the means by which the signalling instruments and points
and signal levers at one station are interlocked with each other.
I will now
describe additional appliances whereby the signalman at one station can control
operations of the signalman at another station. For this purpose, at the one
station I apply to the spindle or sliding rod of the block signalling instrument
a trigger or detent connected to the armature of an electro-magnet, the coil of which
is in circuit with the line wire and indicating instrument from the other station.
When this indicating instrument gives the proper signal, the electro-magnet con-
nected to it acting on the armature causes the detent or trigger to engage with or
disengage from a stop on the spindle or rod so as to prevent it from being moved,
or to permit it to be moved, as the case may be.
In order to explain the application of this part of my Invention I will recur to
the case already given in illustration of the preceding part. I have there said that
B having put his levers right, signals back to A, "line clear;" by this operation he
can by the means last described release the spindle or rod of A's signalling instru-
ment, thereby permitting A to work it so as to lock or unlock his own levers.
I have above described my Invention as applied in connection with levers for
working points and signals, as these are the instruments most commonly used for
that purpose. It is, however, evident that by suitable modifications of the mechan-
ism it is equally applicable in connection with instruments of other kinds that may
be employed for working points and signals.
DESCRIPTION OF THE DRAWINGS

page_text: On
Fig. 2
being interlocked in any of the modes usually employed for that purpose.
represents a front view, shewing the said nine levers by dotted lines, with the
electrical block and interlocking apparatus according to my Invention applied to
them. Fig. 3 represents a transverse section through the lever frame with one of
the levers F in its normal position. In this case I have assumed the interlocking of
the levers to be effected by means of the movement of their spring catches; it is to
be understood, however, that the action of the electrical apparatus is applicable to
levers interlocked in other ways. Figs. 4 and 5 are vertical sections on planes at
right angles to each other of electrical block instruments, with the modifications
necessary for their working according to my Invention. Figs. 6, 7, and 8 are sec-
tional plans of the said instruments on the lines X, Y, and Z of Fig respectively.
Figs. 9, 10, and 11 shew details of locking which will be hereafter referred to.
a framing B, I mount at a convenient level for the eye and hand of the operator a
pair of electrical block signalling instruments C for the up line, and a pair for the
down line, each of these being provided with a vertical spindle D, worked by a
handle d. On the spindle D is fixed an angle plate e, one side of which, marked
"line blocked," is presented at an aperture e', when the handle is turned to the
one position; and the other side marked "line clear" is presented at the aperture
when the handle is turned one quarter round. The plate e carries by an arm an
insulated piece of metal e², which when the handle is turned is brought to bear on
two springs c³, so as to complete the electric circuit from the next station. On the
arm is a pin e, which works along the sloped face of a spring lever e', so that if
the handle be turned not quite to its definite position in either direction it is caused
to spring into that position. On the upper part of the plate e there is a flat face
with a hole in it into which enters a stud projecting from the armature c" of an
electro-magnet e; when the stud is in the hole the spindle D cannot be turned,
but when from the next station an electrical current is transmitted through the
coils of the electro-magnet e", the armature e being attracted upwards, raises the
This portion of the
stud out of the hole, leaving the spindle free to be turned.
mechanism may be dispensed with when it is not necessary to control the move-
ment of the spindle D from another station. Each of the spindles D has on it a
crank or arm ', which engages with a jaw or gab on a horizontal sliding bar d², of
which bars there are as many as there are spindles D.
On each of these bars are fixed in suitable places stops or locks 3, which operate
on the interlocking gear of the point and signal levers in the following manner :-
When it is intended to move one of these levers F its spring catch fis grasped by
the hand, so as to free the lever by raising the end of the rod 1 out of the notch of
the quadrant f; but this movement, acting also on the rocker f, causes to be
partly turned one of the rocking spindles f. In the one position of the sliding
bar d this spindle is free to turn, as indicated by the dotted lines in Fig. 2, or,
as is more clearly shewn to an enlarged scale in Fig. 9, but being so turned it
prevents the sliding bar from being moved in the direction of the arrow, and
thereby locks the spindle D. If, on the other hand, by the partial rotation of D
the sliding bar has been moved in the direction of the arrow so as to bring the
stop or lock immediately over the rocking spindle f, then this spindle caunot
be turned to the position indicated by the dotted lines and consequently the spring
catch rod cannot be raised out of the quadrant notch, the main lever F being thus
locked in its position. In the case of some of the levers of the system locks of a modified
form are required, as I will now describe. In one form, shown to an enlarged scale
in Fig. 10, the sliding bar has on it a pawl d', which by the movement of the bar
d can be drawn over the rocking spindle f". The spindle itself can then be turned
to the dotted position f, and after that the bar d² can again be slid back towards
the right, the pawl d' rising over the spindle f, and dropping down behind it, so
that the bar cannot again be slid toward the left until the spindle fi has been
turned back to the position f. Another special form of lock is shewn at ‹³ in
Fig. 2, and to an enlarged scale in Fig. 11. In this case the spindle f" cannot be
turned until the bar d with its lock has been moved to the right. The spindl

page_text: then being turned to the position indicated by the dotted lines holds the lock d³
within it, but as the lock is free to slide on the bar that bar may be slid to tho
left, leaving the lock d engaged within the spindle. On now turning that
spindle to the horizontal position, so as to leave the lock free, that lock is drawn
by the helical spring back to its normal position on the bar d. In what has
preceded I have described the interlocking of the electrical block signal instru-
iments C with the point and signal levers F as being effected by means of upright
spindles D.
On Sheet II. I show a modification, according to which the interlocking is effected
by the up-and-down movement of rods G, Fig. 12, representing a front view of this
modification as applied to a set of 8 point and signal levers, and Fig. 13 being a
vertical section through the lever frame. In this case the handles g of the instru-
ments C work vertical connecting rods G, which are connected at their lower ends
to rocking spindles g' similar to those which are worked by the spring catches of
the main levers F, as alrendy described. The rocking spindles g' work sliding bars
d, as described in reference to the Figures on Sheet I., whereby is effected the
interlocking with the main levers. Moreover, by means of the rocking spindles g
the sliding bars connected to the several instruments C may be made to lock or
unlock with each other, or with the sliding bars of the lever locking gear, and
thereby the several instruments C may be interlocked with one another, or with
the point and signal levers. I have not thought it necessary to shew in detail
the construction of the instruments C applicable in this arrangement, as it would
be generally similar to that already described and shewn in Figs. 4, 5, 6, 7, and 8 of
Sheet I.
On Sheet III. I have shewn a modification of the mechanism, such as may be
adopted when the point and signal levers are interlocked directly, and not through
their spring catches. Fig. 14 represents a front view of a set of 9 point and signal
levers to which this arrangement is applied; Fig. 15 is a cross section through
the lever frame; Fig. 16 is part of a longitudinal section; and Fig. 17, part of a
plan shewing the mode of locking, and Fig. 18 is a part plan showing a particular
modification applicable in certain cases. Each of the electrical block instruments C
is provided, as first described, with a vertical spindle D, which has an arm &
engaged in a gab of a sliding bar d². To these sliding bars are jointed vibrating
bars or locks, which have on them shoulders that by the movement of the bar d
in the direction of the arrow are brought behind some of the levers F, so as to lock
them. In some cases a modification, such as is shewn in Figs. 16 and 17, is required.
One of the levers F has jointed to it a bar d', which slides across the bar d
When is in a certain position a notch in it is presented so as to allow a projection
on the bar to pass through the notch. This projection having by the movement
of in the direction of the arrow passed the notch, and the lever F¹ having been
pulled over, the bar d² having the slide of its projection sloped, as shewn at do, is
free to move back to the right, raising the bar d' as it passes, but having so moved
the bar d' drops behind d, preventing the bar & from being again moved to the
left until the lever F is replaced in its normal position, bringing the notch in 'to
face the projection . In Fig. 18 the locking bar is connected to the sliding
bar d by a spring. The bar d² being moved in the direction of the arrow a stud
on it moves the lock to the left, leaving the lever 1 free to be pulled back to
the position indicated by the dotted lines F. In this position the lock d' is pre-
vented from returning to the right, but the bar d may nevertheless be slid back to
the right, stretching the spring, which, on the lever F2 being moved back to its
normal position, causes the lock d³ to move its shoulder behind it, locking it as before.
On Sheet IV. I have shewn an arrangement, according to which the block sig-
nalling instruments are worked by levers which are similar to those employed for
working the points and signals, and which are interlocked therewith. In this case
F, F, are the ordinary point and signal levers interlocked in any known manner,
and in the same range and interlocked with them are other levers F¹, which by

page_text: means of connecting rods G work the signalling instruments C, and also rocking
spindles g, and where necessary for interlocking sliding bars d
It will be observed that the modifications in this arrangement consists merely in
making the operating handles of the signalling instruments in the form of hand
levers, and transferring them to such a position that they range with the point and
signal levers, so that they can be conveniently worked in connection therewith;
but I lay no claim to the use of such hand levers for working electrical signalling
instruments.
Although in what precedes I have described a particular form of signalling instru-
ment, suited for operating in the manner set forth, it may be readily understood
that block instruments of other known forms can be adopted for working in a
similar manner by providing them with a spindle or connecting rod, whereby the
movement which completes the electrical circuit at the instrument is also conveyed
to the interlocking gear of the point and signal levers.
Having thus described the nature of my Invention, and in what manner the
same is to be performed, I would have it understood that I make no claim to any
electrical connection of the point or signal levers at one station with signalling
instruments, or with point or signal levers at another station, whereby the working
of these levers at one station can control or be controlled by the working of the
like levers at another station, but I claim,-
First. Connecting the contact makers of electrical block signalling instruments
at a railway station with the ordinary interlocking gear of the point and signal levers
at the same station, so that the signalling instruments cannot be made to transmit
the signal of "line clear" unless the points and signals have first been put in proper
position for the passage of a train, and that while the signalling instruments remain
in condition to transmit the signal "line clear" the points and signals cannot be
put out of proper position, substantially in the manuer and for the purposes herein
set forth.
Second. In block signalling instruments connected to the interlocking gear at a
railway station in the manner referred to in the preceding claim providing detents
worked by electro-magnets communicating electrically with other stations, so that
these instruments cannot be put in condition to transmit the signal of "line clear
unless their detents are released by electric impulses transmitted from the other
stations, substantially as and for the purposes herein described.
"
In witness whereof, I, the said Charles Hodgson, have hereunto set my hand
and seal, this Twenty-fifth day of June, in the year of our Lord One
thousand eight hundred and seventy-seven.
C. HODGSON. (L.S.)