Interlocking Signals and Switches.
Year: 1884

page_text: Interlocking Signals and Switches.
I, CUTHBERT ELLISON CARR, of Lovaine Place in the City and County of
Newcastle-upon-Tyne, Engineer, do hereby declare the nature of said invention
for IMPROVEMENTS IN ACTUATING AND LOCKING SWITCHES AND INTERLOCKING
SIGNALS AND SWITCHES to be as follows:-
"
"
"
My invention relates to safety locking apparatus by means of which the "points
(or "switches") are unlocked, the signals interlocked with the "points," the
ແ points" (or "switches") moved and re-locked and the safety-bar operated so as to
prevent unlocking during passage of a train by one movement of the lever in
signal cabin and comprising the following parts viz:-
The safety bar and its attachment for enabling it to be worked in connection
with points.
The mechanism for unlocking, changing and re-locking the points and
The safety indicating mechanism interlocking the points with the signal levers
in cabin to inform signalınan when points are not in perfect working order.
When it is desired to move the points, the signals are of course raised as at
present to block the line against all approaching trains. The lever that is to
actuate the points or switches being now free is pulled over, and by means of the
connecting rods acting through bell cranks in the usual manner communicates
motion to the points by mechanism to be presently described.
Nearly opposite to the points (or switches) the connecting rods will be attached
to one arm of a bell crank and from the other arm a switch rod runs across the line
below the rails. Near its junction with bell crank this switch rod bends upwards
for the purpose of operating the safety bar which I will now describe.
This safety bar is of peculiar construction it turns horizontally upon pivots and
is counterweighted so as to balance accurately and is actuated by the bent part of
the transverse switch bar passing through an eye, raising and depressing a lever
(attached to the safety bar) as it passes backwards and forwards.
This action of the lever forces the safety bar into a position which it can only
attain when a train has not arrived at, or has safely cleared, the points. A safety
bar made on this principle need not act upon the flanges of the wheels but may act

page_text: upon the outsides of the tires or rims or other convenient portion of the passing or
standing train. It can therefore be placed outside the rail where there is more
room for it and where it does not interfere with the mechanism for actuating the
switches. It also has the advantage of being much lighter to work than any of
the kinds at present in use.
In order to ensure that it shall not throw a train off the line, in case of one
coming up while it is pushed forward, the ends are bent slightly back in the
manner of a guard-rail so that the wheels will force it aside from the rail and if
broken it would be much less likely to cause an accident than those at present in
use which in such a case would probably be forced between the points.
The mechanisin for unlocking, changing and re-locking points is as follows:-
At proper points upon it, the transverse switch bar from the bell crank is
attached freely to the under side of two discs preferably of cast steel of peculiar
shape placed horizontally near the level of underside of rails between the tongue
pieces of the points or switches.
These discs actuate the switches in the following manner.
I will assume that a set of facing points at a junction are open for the main line.
Then the main line signals are down but free to be put up. The lever to actuate
the points, and the lever to actuate the branch signals, are locked by the main
signal lever. It is desired to close the points for the main line and open them for
the branch. The main line signals are put up and release the lever which actuates
the points.
All signals both main line and branch are now up. The main line
signal lever and the switch lever only being free to move.
The switch lever is now pulled over and locks the main line signal lever the
moment it begins to move. The switch lever, as it comes fully over, releases the
branch line signal lever. The movement of the points also releases the branch
line signal lever and locks the main line signal lever as they come to rest.
The operations of the discs are as follows:-
The main line being open the point (or switch) on one side is closed against the
rail of main line and the other side point (or switch) is full open. The two discs
, are now in one of their extreme positions, one pressing the, switch tongue close
against the rail of main line and the other locked in opposite tongue keeping it
full open.
The switch lever in cabin now being moved to close the main line and
open the branch, puts in motion the transverse rod which causes the discs to
revolve on their fulcrum pins, that which was pressing the switch tongue against
main line rail, moving away from the tongue and the opposite disc withdrawing
the lock out of the space between the opposite switch tongue and the rail, and, as
the switch lever is moved over into its extreme position, the discs are further
revolved by the action of the transverse rod, one pressing against the open tongue,
now unlocked, to close it against the rail and the other allowing the tongue (which
it previously was pressing close) to open and simultaneously locking it when full
open, the main line now being closed and the branch open. The branch line signal
levers being now free from both locking arrangements the signals may be lowered,
but if the points have not fully closed, they cannot be lowered on account of iny
locking arrangement which I will presently fully describe. To re-open the main
line and close the branch the action is exactly reversed and the discs and switch
tongues return to the position with which I commenced. The first part of the
revolution of the discs takes place simultaneously with the placing of the safety
bar, before described, over the main rail and cannot be much more than begun
unless the line is clear.
During the last portion of the revolution of the discs (the line being clear) the
safety bar resumes its normal position owing to its lever being depressed by the
second portion of the bend on the transverse bar. The faces of the discs actuating
the switches may be so shaped that the motion which one disc gives to one switch is
exactly simultaneously with the motion which the other disc allows or gives to the
other switch or the faces may be so shaped that the motion of the disc releasing one
point slightly precedes that of the other disc which is actuating the points. Each

page_text: disc is furnished with a locking tail which passes between the opening point and
the fixed rail. This tail may be either pointed or cut off square. If pointed it
works as a wedge entering between the tongue and the main rail (and may be
arranged to fit into the recess between the top and bottom flanges of the rail)
simultaneously with or immediately following the motion imparted through the
rod by the action of the other disc. Thus both the discs are operating, the one to
close one of the switch tongues against the main rail and the other to press open
the other switch tongue from the rail. At the end of the revolution the pointed
locking tail firmly grips the open switch and holds it fast. If the opening switch
has not worked properly the locking tail of the disc is jammed against it and by
prematurely bringing the motion to an end warns the signalman that something is
wrong. If the opening switch has worked properly, the square ended tail of the
disc passes between it and the fixed rail, grips the end of the switch and holds it
firmly. We have seen that unless one switch be fully closed and the other fully
open the motion of the whole apparatus comes to a premature stop which ought to
make it clear to the signalman in cabin that something is wrong, but cases have
occurred with somewhat similar mechanism in which some yielding, in the long
connecting rod or elsewhere, has allowed the lever in cabin to go fully over, thus
deceiving the signalman and enabling him to lower the signals improperly.
With the object of preventing the possibility of this occurring I propose to apply
the safety indicating mechanism which I have already named.
This mechanism may be operated either by the action of the discs direct or from
the motion of the switch tongues and I will first describe the former plan.
A sinal transverse rod crosses the rails underneath the switches and the discs
and has upon it two projections upward except for which the discs would move
freely through their whole range without moving the rod. These projections are
at such points on the rod that they only come into contact with the edges of the
discs as they make about the last inch of their movement.
The outer end of this transverse rod is attached to one arm of a bell crank the
other arm of which is attached to connecting rods which are carried back to the
cabin and there attached to the home signal levers in such a way that only one set
of signals can be lowered at once, and then only when the points are exactly in
their proper position, as the signal levers are locked by the safety gear unless one
or other disc moves the transverse rod by coming against one of its projecting
studs which cannot happen till the switch tongues are completely home.
When the safety indicating mechanism is operated by the switch tongues direct
the discs are somewhat modified in shape. Instead of the motion, which each in
turn gives to one or other switch tongue, being simultaneous with and reciprocal
to the motion of the other and the switch tongues being connected by a rigid tie
bar as is ordinarily the case the discs are so shaped that the motion which they
communicate to the switch tongues is not simultaneous and reciprocal. Thus
arranged the open switch tongue is opened more than the usual extent and has
more movement than the closing tongue. In changing the points the first part of
the motion of the discs does not affect the switch tongues, except to release them;
then to close the open tongue to the standard distance (about 4 inches from fixed
rail). Then, and not till then, the further closing of the tongue begins to affect the
closed tongue, by the tie-rod, and causes it to open while closing the other. By
the time the latter has completely closed the former has opened about 4 inches ;
the further revolution of the disc against the closed tongue does not affect it
except to lock it. The tail of the opposite disc now comes into play and forces
the opening tongue further open and this further opening works the transverse rod
of the safety mechanism and interlocking gear in signal box as described before.
In this modification the tie-rods must not be rigid but have an amount of play,
so as to allow the tongues to approach each other a little nearer than their normal
distance but not, under any circumstances, to allow them to be separated more than
their normal distance apart.

page_text: My plan of interlocking the points and signals is intended solely for the purpose
of informing the signalman in a manner that cannot be mistaken or neglected if
anything has ocurred to prevent the complete and perfect working of the points.
It is not intended to supersede but to supplement the existing systems of
interlocking point and signal levers to secure the proper sequence and combination
of the signalman's operations.
Although I have described my invention as a combination of parts forming a
perfect safety apparatus, it may he applied in some cases, to meet existing
arrangements, without the form of safety bar described, or without the safety
indicating mechanism.

page_text: Interlocking Signals and Switches.
I CUTHBERT ELLISON CARR of Lovaine Place in the City and County of
Newcastle upon Tyne, Engineer, do hereby declare the nature of said Invention
for "IMPROVEMENTS IN ACTUATING AND LOCKING SWITCHES AND INTERLOCKING
SIGNALS AND SWITCHES to be particularly described and ascertained in and by
the following statement:-
喜
"
My invention relates to safety locking apparatus by means of which the
points" (or "switches") are unlocked, the signals interlocked with the points"
the "points" (or "switches") moved and relocked and the safety bar operated, so
as to prevent unlocking during passage of a train, by one movement of the lever in
signal cabin or other actuating mechanism and comprising the following parts viz:
The safety or locking bar and its attachment for enabling it to be worked in
connection with points.
The mechanism for unlocking changing and relocking the points and-
The safety indicating mechanism interlocking the points with the signal levers
in cabin to inform signalman when points are not in perfect working order.
When it is desired to move the points the signals are of course raised as at
present to block the line against all approaching trains. The lever that is to
actuate the points or switches being now free is pulled over, and by means of the
connecting rods acting through bell cranks in the usual manner communicates
motion to the points by mechanism to be presently described.
Nearly opposite to the points (or switches) the connecting rods will be attached
to one arm of a bell crank and from the other arm a switch rod runs across the
line below the rails-Near its junction with bell crank this switch rods bends
upwards for the purpose of operating the safety bar which I will now describe, or
the safety bar may be operated by a separate rod having the requisite form.
This safety bar is of peculiar construction it turns radially upon horizontal pivots
and is counter weighted so as to balance accurately and is actuated by the trans-
verse switch rod raising and depressing it as it passes backwards and forwards or
as above named by a separate rod.
This action of the lever forces the safety bar into a position which it can only
attain when a train has not arrived at, or has safely cleared the points. A safety
bar made on this principle need not act upon the flanges of the wheels but may act
upon the outsides of the tires or rims or other convenient portion of the passing or
standing train-It can therefore be placed outside the rail where there is more
room for it and where it does not interfere with the mechanism for actuating the
switches.
The mechanism of unlocking changing and relocking points is as follows:
At proper points upon it, the transverse switch rod from the bell crank is attached
freely to the under side of two discs or cams preferably of cast steel of peculiar

page_text: shape placed horizontally near the level of underside of rails between the tongue
pieces of the points or switches.
These discs actuate the switches in the following manner.
I will assume that a set of facing points at a junction are open for the main line-
Then the main line signals are down but free to be put up. The lever to actuate
the points and the lever to actuate the branch signals are locked by the main signal
lever. It is desired to close the points for the main line and open them for the
branch. The main line signals are put up and release the lever which actuates the
points.
All signals both main line and branch are now up.
and the switch lever only being free to move.
The main line signal lever
The switch lever is now pulled over and locks the main line signal lever the
moment it begins to move. The switch lever, as it comes fully over releases the
branch line signal lever. The movement of the points also releases the branch line
signal lever and locks the main line signal lever as the points come to rest.
The operations of the discs are as follows:
The main line being open the point (or switch) on one side is closed against the
rail and the other side point (or switch) is full open--The two discs are now in one
of their extreme positions, one pressing the switch tongue close against the rail and
the other locked in opposite tongue keeping it full open-The switch lever in cabin
now being moved to close the main line and open the branch, puts in motion the
transverse rod which causes the discs to revolve on their fulcrum pins, that which
was pressing the switch tongue against rail, moving away from the tongue and the
opposite disc withdrawing the lock out of the space between the opposite switch
tongue and the rail, and, as the switch lever is moved over into its extreme position
the discs are further revolved by the action of the transverse rod, one pressing
against the open tongue, now unlocked, to close it against the rail and the other
allowing the tongue (which it previously was pressing close) to open and simul-
taneously locking it when full open the main line now being closed and the branch
open. The branch line signal levers being now free from both locking arrangements
the signals may be lowered but if the points have not fully closed they cannot be
lowered on account of my locking arrangement which I will presently fully
describe-To reopen the main line and close the branch the action is exactly
reversed and the discs and switch tongues return to the position with which
I commenced-The first part of the revolution of the discs takes place simul-
taneously with the movement of the safety bar, before described into a position
which it can only occupy when the points are clear of a train and cannot have
proceeded far enough to release the points unless the line is clear.
During the last portion of the revolution of the discs (the line being clear) the
safety bar resumes its normal position (either by its actuating rod or by its own 4
weight). The faces of the discs actuating the switches may be so shaped that the
motion which one disc gives to one switch is exactly simultaneous with the motion
which the other disc allows or gives to the other switch or the faces may be so
shaped that the motion of the disc releasing one point slightly precedes that of the
other disc which is actuating the points. Each disc is furnished with a locking tail 4
which passes between the opening point and the fixed rail. This tail may be
either pointed or cut off square. If pointed it may be made to work as a wedge
entering between the tongue and the main rail (and may be arranged to fit into
the recess between the top and bottom flanges of the rail) simultaneously with or
immediately following the motion imparted through the rod by the action of the 5
above disc. Thus both the discs would operate, the one to close, one of the switch
tongues against the rail and the other to press open the other switch tongue from
the rail. At the end of the revolution the locking tail intervenes between the open
switch and the fixed rail and would prevent the switch closing if through anything
going wrong it had any tendency to do so. If the opening switch has not worked 55
properly the locking tail of the disc is jammed against it and by prematurely
bringing the motion to an end warns the signalman that something is wrong. If

page_text: the opening switch has worked properly, the tail of the disc passes between it and
the fixed rail and secures it from closing. We have seen that unless one switch be
fully closed and the other fully open the motion of the whole apparatus comes to
a premature stop which ought to make it clear to the signalman in cabin that
something is wrong. As an extra precaution I propose to introduce the safety
indicating apparatus to which I have before referred.
This safety indicating and interlocking mechanism may be operated either by
the action of the discs direct or from the motion of the switch tongues and I will
first describe the former plan..
A small transverse rod crosses the rails underneath the switches and the discs
and is so contrived that only the movement of the disc opposite the opening switch
actuates it and as this disc cannot complete its revolution unless the switch comes.
fully open and as the opening switch is only actuated by the closing switch the
fact that the signals are free clearly shews that both switches are in their proper
positions.
If the safety indicating mechanism is worked from the switch tongues, the
transverse bar or the tongues are furnished with bosses or projections so that the
bar is only moved by the switch which is in the act of opening and as this is only
moved by the switch tongue which is closing the proper working of the transverse
bar is a positive proof that both switch tongues have come full over. As a further
precaution the tie bars uniting the two switch rails may be slotted so as to allow
the switches to approach a little nearer than the standard distance-In this case
after the opening switch had been drawn over the usual distance by the closing
switch the tail of the disc between the former and its fixed rail would continue to
press it further open and this further opening of the open switch would impart
to the transverse bar the extra motion which would in this case unlock the signals.
My plan of interlocking the points and signals is intended solely for the purpose
of informing the signalman in a manner that cannot be mistaken or neglected if
anything has occurred to prevent the complete and perfect working of the points.
It is not intended to supersede but to supplement the existing systems of inter-
locking point and signal levers to secure the proper sequence and combination of
the signalman's operations.
Although I have described my invention as a combination of parts forming
a perfect safety apparatus, it may be applied in some cases to meet existing
arrangements without the form of safety bar described or without the safety
indicating mechanism
On the accompanying two sheets of drawings I have fully illustrated the manner
in which I propose to carry out my invention in practical application though the
details may be varied without departing from the principle upon which it is based.
Sheet 1, shews three different system of arranging and working the discs or cams,
by which the points are actuated, the safety bar and interlocking signals gear being
applicable to any of the systems but are not shewn.
Sheet 2, shews the general arrangement of a pair of facing points with the
actuating cams and connections, the safety bar and its operation in locking
the points and the means of interlocking points and signals with details of the
several parts.
On Sheet 1, Figures 1, 2, 3, and 4 shew No 1 system of cams in their extreme
and intermediate positions. Figures 5 and 6, shew N° 2 system of cams in their
two extreme positions and Figures 7 and 8 shew N° 3 system of cams. Figure 7
shewing one extreme position, and Figure 8 approaching the other extreme position.
Figure 1 shews switch or point S pressed close up to rail R by the action of the
disc or
<< cam C while the opposite "switch" or point" S¹ is full open and so
locked by the disc or." cam C¹.
"
"
"

page_text: " cam
In Figure 2 the disc or
C having rotated on its fulcrum F by the move-
ment of connecting bar B in direction of the arrow, is releasing switch S from rail R
whilst the disc or 14 cam Cis beginning to close the switch S¹ against the rail R¹
the lock having now been withdrawn.
"
Figure 3 shews the switch S nearly full open and the switch S¹ nearly closed up
to the rail R¹.
"
Figure 4 shews the completion of the movement of the discs or cams the
switches being now in exactly the opposite position shewn by Figure 1 viz. S¹
pressed close against rail R by the disc or "cam" C¹ and S full open and so
locked by the disc or "cam C.
33
Figures 5 and 6 shew the cams C C¹, which are different in shape and are
actuated upon their fulcrums F F¹ by short jointed levers or links L L¹ by a
connecting bar B working in guides G which are necessary to keep its motion
parallel with and equi-distant or nearly so from the sleeper in all positions.
Figure 5 shews switch S pressed close to rail R which switch S₁ is full open and
is locked by the interposing pin P¹ joining the 2 links L L and Figure 6 the other
extreme position switch S¹ being now pressed close to rail R¹ while switch S is full
open and so locked by pin P the intermediate positions being similar to those in
system 1.
Figures 7 and 8 illustrate my third system.
It will be seen that instead of attaching the bar B to pins in the cams C C¹ as
in system 1, the cams C C¹ are rotated on their fulcrums F F¹ by the action of pins
in ends of levers L L¹ working in slots in cams of such a curve as to give the
required motion to the cams, or these curved slots may be in the ends of the
levers L L the pins being in the cams C C¹. The fulcrums of levers L L¹ are on
the next sleeper and they are worked by a rod attached to the tail end of one
lever the connecting bar B transmitting the motion of the other lever. Or the
operating power (manual or other) may be applied direct through the bar B.
Figure 7 shews switch S closed and pressed against rail Ŕ by disc or cam C
and the switch S¹ full open and so locked by the tail of cam C¹ interposing
between the switch and rail R¹, Figure 8 shews switch S¹ closed against rail R¹
(the disc or cam C¹ having yet a small portion of its radial motion to complete by
a further movement of the bar B, in direction of the arrow before it assumes the
position of cam C on Figure 7) and switch S full open and so locked by the tail
of cam C.
'
It will be seen that my three plans are three slightly different methods of
carrying out the same idea viz: First that the closed switch shall be firmly
pressed against its fixed rail in a manner which no direct outward pressure can
overcome unless it is powerful enough to break up the apparatus and that the
pressure keeping the switch close against the fixed rail shall be applied direct to
the switch itself.
That a portion of the mechanism shall interpose between the open switch and its
fixed rail so that if anything severs the fastenings uniting the two switches there
shall be no danger of the open one shaking against the fixed rail and thus causing
an accident.
That this shall be done in one continuous motion by means of the radial
movement of the discs or cams however operated and whether by manual or other
power.
To accomplish this it is necessary to delay or reduce the motion given to the
closing switch so that the disc or cam pressing against the switch previously closed
may have time to get clear and allow such previously closed switch to be drawn
open by the one now closing.
My first stystem accomplishes this through the peculiar shape of that portion of
the disc or cam which presses against the closing switch.
My second system effects the desired delay by the interposition of the link
which delays the forward motion of the point until the corresponding point on the
other disc or cam has been drawn out of the way of the opening switch.

page_text: My third system effects the necessary delay in the movement of the closing
switch by means of the slots in discs or cams or by equivalent slots in ends of
levers which operate the discs or cams.
On Figures 1. 2. 3 and 4 is shewn a safety device K hereafter described which
may be applied in modified forms to the other two systems.
On Sheet 2, Figure 1 shews on plan the general arrangement of a set of facing
points open to the main line and closed to the branch and Figure 2 shews a trans-
verse section on line a b of Figure 1 R R¹ are the main rails S S₁ the points or
switches S being closed and pressed against rail R by the cam C and S¹ being full
open and so locked by the interposing tail of cam C¹ between it and the rail R¹.
The cams C C¹ work on fulcrum pins F F¹ passing through tie beams A firmly
bolted to main sleepers D extended outward at one side and also through a
transverse beam E which extends outward to take the fulcrum of the bell crank G
by which motion is communicated from the signal cabin through the connecting
rod H to the switch bar B attached freely to the cams C C. The safety device K
previously referred to is attached to main rail and would, in case of any accidental
disturbance of the fulcrum of either cam indicate something wrong by preventing
either cam or both being actuated to their proper extent by the switch bar B by
the projecting end (L) coming in contact with the heel (M) of thick portion
of cam.
Figures 3 and 4 shew section through e. f and g. h respectively on Figure 1
shewing the relative positious of the discs or cams C C the rails R R' the
switches S S' and the safety device (K).
Figure 5 is an enlarged section on line c. d of Figure 1 shewing detail of the
mode in which I consider a firm attachment may be made of the fulcrum of the
cams to permanent way.
I have shewn one form of safety or locking bar which appears to me to be
specially applicable on Figure 1 and details of same on Figures 6 and 7 but any
other ordinary safety bar may be applied to my switch apparatus.
Figure 6 shews the safety bar N in the position it will assume while the points
are being changed and are clear of a train standing on or passsing over them the
rod Q moving in the direction of the arrow having raised the locking piece O onto
projecting part of the rod releasing the lock and allowing the bell crank G to
actuate the points.
Figure 7 shews the bar N in the position it will assume when a train is standing
upon or passing over the points, the wheels or some of them preventing it from
rising and keeping the locking piece O in contact with projecting part of the rod Q
thus locking the rod and with it the bell crank G preventing the points being
moved.
The signal and switch interlocking gear indicating by connection with the signals
whether the points are full over and preventing signals and points being wrongly
actuated, which I prefer to use with my switch apparatus is shewn by Figure 1. 2.
8 and 9. Figure 1 being a plan and Figure 2 a section (on line a. b Figure 1)
shewing connection of locking rod U by loops with cams CC. Figure 8 a section
(on line o. p Figure 1) and Figure 9 a section (on line q. Figure 1). The main
line being open and the branch closed the main line signal is lowered see Figure 9
the projecting piece S on rod T attached to signal wire entering an eye in rod U
but the branch signal is raised and cannot be lowered until the points are changed
the projecting pin S' on rod T¹ not being opposite the open eye or rod U see
Figure 8. In like manner the points cannot be changed until the main line
signal is raised to danger.
Whatever system of interlocking the signals with the points may be adopted a
special feature of my invention is that the signal can only be released by the extra
motion of the disc or cam opposite the opening switch such extra motion taking
place only after the closing switch is completely closed against fixed rail so that
the accidental interposition of any obstacle, no matter how small, would prevent
the release of the signal by preventing the further radial movement of the disc,

page_text: When slotted switch bars are used it will be the extra motion of the opening switch
allowed by the slotted switch bar, which will release the signal only after the
closing switch has been completely closed.
Having now fully described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what
I claim is
First. Effecting the unlocking changing and relocking of one or both points or
.switches in the sequence and with the objects set forth, by means of cam shaped
.discs moved radially on fixed fulcrums by connecting bars and levers attached to
them by pins, the whole constructed and operating substantially as shewn and
.described.
Second. The improvements in actuating and locking switches and interlocking
signals therewith consisting of the combination of cam shaped discs, moving
radially on fixed fulcrums, with safety or locking bar and signal interlocking
mechanism the whole constructed and operating substantially as shewn and
described.
Dated the 13th day of August 1885.
Witness:
T. J. DANSON, F. Inst. P.A.,
Consulting Engineer & Patent Agent,
Newcastle-upon-Tyne.
CUTH E. CARR,