IMPROVEMENTS IN INTERLOCKING APPARATUS OF RAILWAY POINTS AND SIGNALS
Year: 1872

page_text: LETTERS PATENT to John Imray, of No. 20, Southampton Buildings,
Chancery Lane, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN INTERLOCKING APPARATUS OF RAILWAY POINTS AND
SIGNALS."
Sealed the 2nd July 1872, and dated the 3rd May 1872.
PROVISIONAL SPECIFICATION left by the said John Imray at the
Office of the Commissioners of Patents, with his Petition, on the
3rd May 1872.
I, JOHN IMRAY, of No. 20, Southampton Buildings, Chancery Lane,
in the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN INTERLOCKING APPARATUS OF RAILWAY
POLITS AND SIGNALS,” to be as follows :-
For working the points and signals of railways at junctions and else-
where there is usually a row of levers, some for shifting the points and
some for raising and lowering the signals, and those levers are generally
provided with interlocking gear whereby their movements are con-

page_text: trolled, so that danger cannot arise from the shifting of a point when
the signals or other points are not set suitably for such shift, nor from
the giving of a signal when the points or other signals are not set
suitably for such signal being given.
My Invention relates to the construction of and mode of arranging ‘5
and working interlocking gear applicable to such a system of point and
signal levers, the object of my improvements being to secure cheapness
and compactness of construction and safety and simplicity in working.
For this purpose for every lever of the row I mount a rocking shaft in
bearings so that its axis is in the line of the lever's movement. This 1
rocking shaft is conveniently made of a hollow semi-cylindrical form,
with trunnions or pivots at each end on which it can rotate. In one
part of its length there is a long slot within which the lever can work
to and fro, and at each end of this slot at opposite sides of it there is a
lateral notch or recess which receives the lever when the rocking shaft 1
is turned partly round on its axis, and which holds the lever at either
end of its stroke until the rocking shaft be turned back so as to bring
the long slot into the line of the lever's motion. While the lever moves.
along the slot the rocking shaft is prevented by it from turning. :
Each lever is provided with a spring catch of ordinary construction. 2
The lower end of the spring catch rod is made with projections arranged
to act on the rocking shaft in the following manner :-When the lever is
at the one end of its stroke in the slot of the rocking shaft and engaged
in the side notch thereof, the spring catch rod being raised by the
action of the hand in grasping the spring catch, one of its projections 2
acts on the rocking shaft so as partly to turn it and thereby to disengage
the lever from the side notch and to present to it the long slot in which
it can work. The lever can then be pulled or pushed along the slot till
it reaches the other extreme of its stroke. On letting go the spring
catch its rod descends and another of its projections acts on the rocking 3
shaft so as to turn it farther round and thereby to engage the lever in
the side notch at the end of the slot which it has reached. Thus every
stroke of each lever in either direction is accompanied by two successive
movements of the rocking shaft effected by means of the spring catch,
the one partial movement disengaging the lever before it has been moved 3
at all and the other partial movement in the same direction engaging
the lever after it has been moved fully over. Each rocking shaft extends

page_text: some distance beyond its lever over or under a series of horizontal bars
mounted in guides so that they can slide to and fro in a direction
parallel to the row of levers and therefore transversely to the rocking
shafts. Some of these rocking shafts have cranks or arms projecting
vertically from them and engaging in notches or on pins or rollers on
some of the sliding bars in such a manner that these sliding bars are
caused to move to or fro by the partial rotation of the rocking shafts
connected to them. Others of the rocking shafts have lips projecting
vertically from them at some distance from their axes of motion. On
each of the sliding bars there are at suitable places stops, projections, or
notches presented to the projecting lips of the rocking shafts, so as to
effect with them a reciprocal locking action which will be best under-
stood by describing a simple case of interlocking. Assuming that thero
are three levers, one for shifting a point so as to guide a train from a
main line to a branch, one for working the signal for the main line, and
one for working the signal for the branch line, then there is one sliding
bar worked by the rocking shaft of the point lever, and on it there are
two stops, one presented to the lip of each of the rocking shafts of the
signal levers. When the three levers are in their forward position let
the point be set right for the main line and let both signals be up at
danger. In this case the first stop on the bar is clear of the lip of the
main signal rocking shaft, but the second stop faces the lip of the
branch signal rocking shaft. Either the point lever or the main signal
lever can then be moved, but the branch signal lever is locked, because
the lip of its rocking shaft is obstructed by the second stop on the bar.
If now it be intended to lower the main signal (so as to pass a train
along the main line) its rocking shaft is partly turned by the action of
the spring catch, and its lip then presents an obstruction to the first stop
on the sliding bar, and thus the point lever which is connected to that
bar is locked and the point cannot be shifted. If on the other hand it
be intended to shift the point from the main line to the branch (both
signals being up at danger) the rocking shaft of the point lever is partly
turned by the action of the spring catch, and the sliding bar is thus
moved so as to bring the first stop in front of the lip of the main signal
rocking shaft and thereby to lock the main signal. This first movement
of the sliding bar also shifts the second stop, but not so far as to carry
it clear of the lip of the branch signal rocking shaft, which therefore
remains locked. When the point lever is pulled fully over, and its spring
catch let go, the sliding bar is moved farther on. The first stop though

page_text: it has moved with the bar still faces the lip of the main signal rocking
shaft and keeps it locked, but the second stop is now moved clear of
the lip of the branch signal rocking shaft, which is thus released. If
now it be intended to lower the branch signal (so as to pass a train
along the branch) its rocking shaft being partly turned by the action of
the spring catch brings its lip behind the second stop, and so
obstructing the sliding bar locks the point lever in its back position.
This mode of interlocking described in reference to three levers may
be extended to any number of levers, and in this manner point and
signal levers may be made to interlock with each other according to any 1
required combinations, the number of sliding bars, and of stops thereon
being suited in cach case to the conditions of the system to which
they are applied.
From what has been described above it will be seen that the first
action of grasping the spring catch, preliminary to the movement of a 1
lever, disengages that lever from its notch and at the same time locks all
such of the other levers as should be locked when that lever is about
to be moved, but unlocks none that were previously locked, and' that
the last action of letting go the spring catch after a lever has been
moved, engages that lever in its notch and at the same time unlocks 2
such other levers as may with safety be released when the said lever has
been moved fully over. Thus the locking is in all cases effected before
the movement of a lever, and the unlocking is never effected until after
the movement of the lever has been completed.
SPECIFICATION in pursuance of the conditions of the Letters Patent a
filed by the said John Imray in the Great Seal Patent Office on the
2nd August 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
IMRAY, of No. 20, Southampton Buildings, Chancery Lane, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Third day of May, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-

page_text: fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Imray, Her special licence
that I, the said John Imray, my executors, administrators, and
assigns, or such others as I, the said John Imray, my executors,
5 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
INTERLOCKING APPARATUS OF RAILWAY POINTS AND SIGNALS," upon the condition
(amongst others) that I, the said John Imray, my executors or adminis-
trators, by an instrument in writing under my, or their, or one of their
bands and seals, should particularly describe and ascertain the nature of
the said Invention, and in what manner the same was to be performed,
5 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 Imray, 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 Sheet of Drawings and to the figures and letters marked thereon,
that is to say :-
For working the points and signals of railways at junctions and else-
5 where there is usually a row of levers, some for shifting the points and
some for raising and lowering the signals, and those levers are generally
provided with interlocking gear whereby their movements are con-
trolled, so that danger cannot arise from the shifting of a point when
the signals or other points are not set suitable for such shift, nor from
O giving of a signal when the points or other signals are not set
suitable for such signal being given.
2
My Invention relates to the construction of and mode of arranging
and working interlocking gear applicable to such a system of point and
signal levers, the object of my improvements being to secure cheapness
and compactness of construction and safety and simplicity in working.
For this purpose for every lever of the row I mount a rocking shaft in
bearings so that its axis is in the plane of the lever's movement.
This

page_text: In one
rocking shaft is conveniently made of a hollow semi-cylindrical form,
with trunnions or pivots at each end on which it can rotate.
part of its length there is a long slot within which the lever can work
to and fro, and at each end of this slot at opposite sides of it there is a
lateral notch or recess which receives the lever when the rocking shaft
is turned partly on its axis, and which holds the lever at either end of
its stroke until the rocking shaft be turned back so as to bring the long
slot into the line of the lever's motion. While the lever moves along
the slot the rocking shaft is prevented by it from turning.
Each lever is provided with a spring catch of ordinary construction.
The lower end of the spring catch rod is made with projections arranged
to act on the rocking shaft in the following manner:-When the lever
is at the onc end of its stroke in the slot of the rocking shaft and
engaged in the side notch thereof, the spring catch rod being raised by
the action of the hand on grasping the spring catch, one of its pro- :
jections acts on the rocking shaft so as partly to turn it and thereby to
disengage the lever from the side notch and to present to it the long
slot in which it can work. The lever can then be pulled or pushed along
the slot till it reaches the other extreme of its stroke. On letting go the
spring catch its rod descends and another of the projections acts on the
rocking shaft so as to turn it farther round and thereby to engage the
lever in the side notch at the end of the slot which it has reached.
Thus every stroke of each lever in either direction is accompanied by
two successive movements of the rocking shaft effected by means of
the spring catch, the one partial movement disengaging the lever before 2
it has been moved at all, and the other partial movement in the same
direction engaging the lever after it has been moved fully over. Each
rocking shaft extends some distance beyond its lever over or under a
scries of horizontal bars mounted in guides so that they can slide to and
fro in a direction parallel to the row of levers and therefore transversely 3
to the rocking shafts. Some of the rocking shafts have cranks or arms
projecting vertically from them and engaging in notches or on pins or
rollers on some of the sliding bars in such a manner that these sliding
bars are caused to move to or fro by the partial rotation of the rocking
shafts connected to them. Others of the rocking shafts have lips pro- 8
jecting vertically from them at some distance from their axes of motion.
On each of the sliding bars there are at suitable places stops, projections,
or notches presented to the projecting lips of the rocking shafts, so as to

page_text: effect with them a reciprocal locking action, which will be best under-
stood by describing a simple case of interlocking. Assuming that there
are three levers, one for shifting a point so as to guide a train from a
main line to a branch, one for working the signal for the main line, and
one for working the signal for the branch, then there is one sliding bar
worked by the rocking shaft of the point lever, and on it there are two
stops, one presented to the lip of each of the rocking shafts of the
signal levers. When the three levers are in their forward position let it
be assumed that the point is set right for the main line and that both
signals are at "danger." In this case the first stop on the bar is clear
of the lip of the main signal rocking shaft, but the second stop faces
the lip of the branch signal rocking shaft. Either the point lever or
the main signal lever can then be moved, but the branch signal lever is
locked, because the lip of its rocking shaft is obstructed by the second
stop on the bar. If now it be intended to lower the main signal (so as
to pass a train along the main line), on grasping the spring catch of the
main signal lever so as to move that lever, its rocking shaft is partly
turned round by the action of the spring catch and its lip then presents
an obstruction to the first stop on the sliding bar, and thus the point lever
which is connected to that bar is locked and the point cannot be shifted.
If on the other hand it be intended to shift the point from the main line
to the branch (both signals being at danger), on grasping the spring
catch of the point lever so as to move it its rocking shaft is partly
turned by the action of the spring catch, and the sliding bar is thus
moved so as to bring the first stop in front of the lip of the main signal
rocking shaft and thereby to lock the main signal. This first movement
of the sliding bar also shifts the second stop, but not so far as to carry
it clear of the lip of the branch signal rocking shaft, which therefore
remains locked. When the point lever is pulled fully over, and its
spring catch let go, the sliding bar is moved farther on. The first stop
though it has moved with the bar still faces the lip of the main signal
rocking shaft and keeps it locked, but the second stop is now moved
clear of the lip of the branch signal rocking shaft, which is thus
released. If now it be intended to lower the branch signal (so as to
pass a train along the branch) its rocking shaft being partly turned by
the action of the spring catch, when grasped before moving the lever
brings its lip behind the second stop, and so obstructing the sliding bar
locks the point lever in its back position.

page_text: This mode of interlocking described in reference to three levers may
be extended to any number of levers, and in this manner point and
signal levers may be made to interlock with each other according to any
required combinations, the number of sliding bars and of stops thereon
being suited in each case to the conditions of the system to which they !
are applied.
From what has been described above it will be seen that the first
action of grasping the spring catch, preliminary to the movement of a
lever, disengages that lever from its notch and at the same time locks all
such of the other levers as should be locked when that lever is about to 1
be moved, but unlocks none that were previously locked, and that the
last action of letting go the spring catch after a lever has been moved
engages that lever in its notch and at the same time unlocks such other
levers as may with safety be released when the said lever has been
moved fully over. Thus the locking is in all cases effected before the 1
movement of a lever, and the unlocking is never effected until after the
movement of the lever has been completed.
Fig. 1 represents a side view of one of a series of levers employed for
working railway points and signals, with a longitudinal section of a 2
rocking shaft applied to it, according to my Invention, for the purpose of
holding the lever at either end of its stroke and working the interlocking
gear. A is the lever provided in the ordinary way, with a spring catch B
and its rod O extending down one face of the lever. At the lower end
of the catch rod C there are formed two projections D and D', and the 2
rod C is pressed down by a helical spring interposed between these pro-
jections and the upper part of the guide in which the rod works.
E is the rocking shaft, of which Fig. 2 represents a plan and Figs. 3,
4, and 5, represent transverse sections respectively on the lines X, X,
Y, Y, Z, Z, in Fig. 1. The rocking shaft E is of hollow, nearly semi- 8
cylindrical form, open along the under side, and is provided at the ends
with trunnions F, F, which work in bearings fixed on the framing of
the apparatus. Along the upper side of the shaft E there is a long slot
in which the lever A can work. At either end of this slot there is a part
laterally recessed G, G³, and H, H'. There are also formed within the 3

page_text: rocking shaft Ẹ on opposite sides of its interior cavity recesses K and L,
into the one of which K the projection D from the catch rod engages
when the lever A is in the position shewn in Fig. 1, and into the other
of which L the other projection D' engages when the lever is brought
5 over to the other extreme of its stroke, as indicated by the dotted
lines A' in Fig. 1. It will be seen that when the spring catch rod C is
down the lever A. at either extreme of its stroke is engaged in one of the.
side recesses H, H³, or G, G¹, and by means of the projecting lip H or G
of the rocking shaft is prevented from being moved. Fig. 5 shews the
O lever so held in the recess H, H. Now on grasping the spring catch
lever B so as to close it towards A, and thereby to raise its rod O, the
projection D acting in the recess K partly turns the shaft E on its axis,
and thereby removes the lip H from behind the lever A. The lever can
then be pulled along the slot in E to the position A' (Fig. 1), tho
5 projection D' entering the recess Ļ. On letting go the spring catch, its
rod C being caused to descend by the spring, the projection D' engaged
in the recess L causes the shaft E to turn still farther round, and thus
brings the lip G in front of the lever, as shewn in Fig. 3. On again
grasping the spring catch the shaft E is turned backwards so as tọ
O remove the lip G. from before the lever, which can then be moved along
the slot to its forward position A, and secured there by the farther
turning of the shaft E backwards, caused by the descent of the pro-
jection D when the spring catch is let go.
It will thus be seen that when the lever A is to be moved there is
5 necessary the preliminary operation of raising the spring catch rod
which partly turns the shaft E, and when the lever has been moved the
letting go of the spring catch still farther turns the shaft E in the same
direction. The movements thus imparted to the shaft E are utilised
for the purpose of working interlocking gear, as I will now. describe.
0 And first it is to be understood that every lever of the series is provided
with a rocking shaft arranged to work in the manner described above,
also that each of those rocking shafts has a part M extending beyond
the slotted part and of such length as may be required for the inter-
locking gear.
.

page_text: to be interlocked, and I refer to Figs. 6, 7, 8, and 9, which shew in
transverse section the positions of the rocking shafts belonging to
the three levers in four different conditions of their relative move-
ments. I will suppose that the middle lever of which M is the rocking
shaft works a pair of points for guiding a train along a main line when
the lever is in the front position A, Fig. 1, and for guiding it along a
branch when the lever is moved over to the position A', Fig. 1. I will
also suppose that M² is the rocking shaft of the lever which lowers the
main line signal, and that M' is the rocking shaft of the lever which
lowers the branch signal. Each of these rocking shafts must as
explained above be moved in the direction of the arrow, Fig. 6, before
pulling back the lever to which it belongs, and is moved still farther in
the direction of the arrow on letting go the spring catch after the lever
has been pulled back. The point lever rocking shaft M has a crank
plate m projecting down from it with a slot which engages on a pin or
stud fixed on a bar N, which is mounted in guides, so as to slide
horizontally in a direction transverse to the rocking shafts or parallel
to the row of levers. On this bar are fixed two stops O and P,
differently shaped, the one O being formed with a curved side to fit
the exterior of the rocking shaft M', and the other P having its other
side curved to fit the interior of the shaft M. The three levers being
all towards the front, as A, Fig. 1, the points being set right for the
main line, and both signals up at "danger," the rocking shafts are in
the position shewn in Fig. 6. In this position the shaft M being
stopped by P cannot be turned, and henco the lever of the branch
signal is locked at danger, but the shaft M' is free, and therefore the
main line signal can be lowered when its shaft M' is turned into the
position shewn in Fig. 7, so as to be in front of the stop O. In this
condition the bar N cannot be moved, and consequently the shaft M
which works it, and therefore the point lever is locked, the branch signal ;
also remaining locked as before. The main line signal being again
raised to "danger" the condition is as shewn in Fig. 6. If now tho
points be shifted the shaft M is turned as shown in Fig. 8, and the
bar N is moved by its crank plate m, so as to bring the stop O under
the lip of the shaft M³, which is thereby obstructed. In this condition
the main line signal is locked at "danger," but the movement of
the bar N having the stop P clear of the lip of the shaft M* the
branch signal can be lowered, and in that case the shaft Mª takes the

page_text: position shewn in Fig. 9, where its lip comes behind the stop P. While
it remains so the bar N cannot be moved back, and consequently the
point lever is locked with the points set for the branch line, as well as
the main signal lever, which remains locked at "danger.”
5 Although Figs. 7, 8, and 9 illustrate the interlocking effected when
the several levers have made their full stroke and the rocking shafts
have turned far enough to release their levers from the recesses at one
end and engage them in the recesses at the other end of their respective
slots, it will be readily understood that the locking is effected also when
0 the rocking shafts make only that part of their stroke which suffices to
release their levers, and that the unlocking is not effected till the
rocking shafts have made their complete stroke, so as to re-engage their
levers. Thus the preliminary operation of raising the catch rod of any
lever effects the locking, and the final operation of letting the catch rod
5 descend effects the unlocking.
The bar N may extend any desired length along the row of levers,
and have on it such stops like O or P as may be required for the purpose
of interlocking. Also there may be several bars like N arranged side
by side, as shewn with respect to three, N, N³, and N' in Fig. 1; and
O where there are many such bars required for the complete interlocking
of any system of levers, the part M of the rocking shafts may be made
of such length as is necessary to accommodate them and their respective
stops.
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
do not claim generally the application of the movement of the spring
catch rod to purposes of interlocking or of holding or releasing a lever
at either end of its stroke, but I claim,—
First. The use of a slotted rocking shaft worked by the spring catch

page_text: locking and unlocking point and signal levers, substantially as herein
described.
In witness whereof, I, the said John Imray, have hereunto set my
hand and seal, this Second day of August, in the year of
our Lord One thousand eight hundred and seventy-two.