An Improved Safety Block System for Railway Signalling.
Year: 1893

page_text: COMPLETE SPECIFICATION.
An Improved Safety Block System for Railway Signalling.
We, WILLIAM ROBERT SYKES, Junior, of 43 Kent House Road, Beckenham,
in the County of Kent, Telegraph Engineer, and JOHN PATRICK O'DONNELL of
70 and 71 Palace Chambers, Westminster, in the County of Middlesex, Civil
Engineer, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-
Our invention consists in an improved method of interlocking the outside visual
signals with the block instruments.
With the existing known instruments at the present time the interlocking of the
block instruments and the outside signals is effected by means of the levers in the
signal box which operate the outside signals.
Briefly, we arrange that, supposing two sections A and B, B is free to accept a
train from A under the normal condition, B plunges through the special instrument,
which we will hereinafter describe, and through the apparatus fixed upon the
signal post he places certain apparatus so that the action of working the lever
operating the starting signal at section A effects the lowering of the said signal.
Assuming that B gives his permission, A operates his starting signal lever, the
said starting signal being deflected; a treadle or rail contact is arranged a suitable
distance in advance of the starting signal and operates that when a train has
arrived and deflected the said treadle or rail contact, the starting signal in its rear
is replaced to the "danger" attitude.
It is immaterial whether the signalman replaces bis starting signal lever or not,
for he cannot lower the starting signal a second time until permission is given
by B. The train having left A has approached B and drawn up under the
protection of B's starting signal; even then B is not in a position to release the
starting signal at A. When the starting signal at B has been lowered by
the operation of B's starting signal lever, the train can then proceed over the
treadle in advance, operate the said treadle and replace B's starting signal to
"danger," a current is taken to the instrument at B, which, if he wishes, enables
him to plunge and release A's starting signal, so that he can accept a second train
from A.
It will thus be seen that whereas at the present time outside signals are
controlled through the movements of their operating levers, in our invention we
practically disregard the levers which operate the said signals, and interlock the
arms themselves.
It is understood that in the event of B accepting a train from A and B wishing
to suspend the sanction previously given, provided the train has not started from A
and depressed the treadle, B has power to reverse his operation and replace A's
starting signal to "danger."
In order that our invention may be better understood and more readily carried
into effect we will proceed to describe the drawings hereunto annexed. The
same numbers refer to the same parts or substitutes therefor in the several
figures.
Figure 1 illustrates two sections, A and B, on an ordinary line of railway.
In this figure 1 is the stop signal at A, 2 the starting signal at A, 3 the stop
signal at B, and 4 the starting signal at B, 5 is the treadle the required distance in
advance of the starting signal at A, and 6 is the treadle in advance of the starting

page_text: Figure 2 illustrates the instrument at A for forwarding a train. The usua!
system for asking instructions for a train by means of a bell is used with our
invention.
Figure 2 illustrates the instrument containing an electro-magnet 8 armature 9,
and arm indicator. In this figure also the lever in the locking frame operating the
starting signal is illustrated. The starting signal itself is also illustrated, showing
the apparatus in the upright rod.
This figure (2) illustrates the receiving instrument at A. 7 is the dial of the
instrument indicating to the signalman at A whether in operating his lever the
starting signal' arm will be deflected or not. In the interior of 7 the electro-
magnet 8 is fixed and the armature 9 and contact 10. 11 is the mechanical lever
in the interlocking apparatus operating the starting signal 2 Figure 1. Behind the
starting signal lever is arranged what we call a contact maker, comprising two
springs 12 and 13, joined together when the catch handle is raised. When the
drop box 14 of the catch handle is raised it allows the two springs 12 and 13 to
come together. 15 is the battery. At the right hand of the battery the wire goes
to earth. The wire from the contact 10 leads to the apparatus fixed in the upright
rod on the post of the starting signal 2. 16 illustrates the position in the upright
rod on the post, of our apparatus. 17 is the line wire from the instrument at B,
being intermediately intercepted by the treadle fixed in advance of the starting
signal at A. 18 is the instrument at B, indicating whether the line is blocked
or not.
<<
"
The act of plunging takes up a current from the battery 20, which at 22 has two
paths or courses, one passing through the arm indicator to a spring 23 arranged on
the armature, the other path passing through the electro-magnet 25 to another
spring 26 arranged on the same armature 27. 28 is a plunger, 29 is a lever at the
back of the plunger. The lever 30 operates the armature 31. 32 is a click
normally holding up the armature 33. The armature piece 33 is centred at 34.
35 is the electro-magnet operated by the treadle. 36 is the wire from the electro-
magnet to the treadle 6 which is a making contact treadle. 37 is a wire leading
to battery 38, 39 is the wire leading from battery 38 to treadle 6. 41 is a wire
running to contact 52". 42 is a spring, 43 is a spring, 44 is the contact connecting
one spring with the other, that is to say, connecting springs 42 and 43, and the
contact is a normal one. 45 is another contact normally disconnected from both
the springs 42 and 43, the wire 46 goes from the contact 45 through the electro-
magnet 47 to earth. A switch consisting of a metal spindle, one end of which is
passed through the front of the instrument case and provided with a handle and
the other end terminates in a metal segment 48 upon which the spring 42 rests, is
provided. 49 is the contact through the resistance to earth, 50 is the insulating
piece on spring 42, 51 is a contact from which a wire 40 leads to another
contact 52. A wire 53 is joined to the wire 24 and passes to the armature 54 ;
a contact 55 and wire 56 join the wire to the magnet 25.
For the purposes of slip coaches and other analogous movements a single
electro-magnet 57 is fixed as shown, an armature 58 in connection therewith and a
loop 59 projecting from the armature 58 operating about the stud 60 in the
lever 32. 61 is the left hand contact piece of the slip bar fixed adjacent to the
stop signal 2 (Figure 1), 62 is the right hand contact piece of the same bar;
a wire 63 runs from the piece 61 to the battery 71. 64 is the left hand contact
piece of the bar in siding, & 65 is the right hand contact piece of the same bar,
which is a divided bar as shown; a wire 66 runs from the right hand contact
piece 62 of the stop signal bar to the magnet 57 and continues to a contact
piece 67. The magnet 57 has a recess so that the thickened portion of the
armature 58 when drawn home is drawn inside the magnet so that the projecting
springs upon the armature 58 make contact with the contact piece 67 in the one
case and 70 in the other. 68 is a wire from the right hand contact piece of the slip
bar in the siding to the magnet 57, 69 is a wire from the battery joining the
wire 63 and going to the contact 70. There are two wires running from the two
•

page_text: pieces 64, 65, of the slip bar in the siding to an ordinary treadle, 6, in advance of
the starting signal. The battery 71 connects the two wires 63 and 68.
An essential feature of our invention consists in the fact that we arrange that
the stop signal lever must be moved in the direction of pulling in order that the
instrument is freed for the signalman to plunge and accept a train from the rear.
This is not an essential feature in the case of junction working.
The working of ordinary through traffic is as follows. A special description
with reference to slip coaches will be described hereafter.
Referring to Figure 1, A is ready to send a train to B and for this purpose
must get B's permission, B works over his stop signal lever, plunges, and (in
Figure 3, 72 is the stop signal lever, 73 the contact underneath the drop box, 74 is
the contact from which wire 75 leads to line wire 17) as the stop signal lever is
pulled over the contact 75 is brought into contact with 74, the circuit is thus
complete. In plunging, 28 is moved inwards and pushes forward the lever 29, 29
through its projection 30 pushes forward the armature 31 making contact with the
electro-magnets 25; this also displaces the click 32 and the armature 33 falls, the
thickened portion falling in front of the click 32 and at back of the lever 29; by
this action the click 32 cannot be moved forward and the lever 29 cannot be moved
forward. The armature 31 in connection with the electro-magnet 25 is in contact
at its lower portion 27 with the contact pieces 52 and 52 with the result that the
current of the battery 20 travels through the indicator 18 and to the electro-
magnet 25; this has resulted in the arm of the indicator instrument at B being
lowered to the "safety" attitude and the current passing from the magnet 25
through the spring 26 making contact 52, along the wire 41 to the spring 42,
contact 44, flowing through spring 43 to the contact 73 through the contact 74,
joining the line wire 17, through the treadle 5, and to the instrument at A
deflecting the arm in that instrument to the "safety" attitude; it also passes
through the electro-magnet 8 to earth. Upon the withdrawal of the hand from
the plunger the lever 29 has a movement towards the plunger and the thickened
portion 33 falls between the lever 29 and the click 32 in its moved position. By
this it will be observed that both the click and the lever, and indirectly the
plunger, are locked in their positions. B further, in plunging, has left a current
on so that the armature 9 is moved up to the electro-magnet 8 in contact with the
contact piece 10; by this the current is on at the contact piece 12, so that A in
operating his starting signal lever, moving up the drop box allows springs 12
and 13 to come in contact. The signalman is now free to operate the lever and
deflect the signal.
It is understood that the starting signal lever is normally free, but under the
conditions named when B has plunged if the starting signal lever is operated the
current passes through the wire 76, through the armature 9, making contact with
the contact piece 10, and so goes to the apparatus 16 fixed upon the post, and
through this to earth. This action allows that when the starting signal lever
itself is operated the arm be deflected. Upon the deflection of the starting signal
and the train proceeding towards B it operates the treadle 5, breaks the line
current and replaces the arm to "danger," allowing the armature 9 to drop from
its contact with the magnet 8, putting the armn to "danger" in the instrument at A
and also in the instrument at B and drops the armature 31 at B. That action
breaks the contacts 52, 52, in fact, breaks all contacts previously made by the
plunging at B.
In order to release B's plunger and enable him to take a second train from A,
the train itself must have passed over the treadle 6 at B in advance of B's
starting signal 4. He makes the contact and raises the armature 33 and allows
the click 32 to fall by gravity to its normal position and also allows the lever 29
to be plunged by B for a second operation.
The method of ordinarily working the switch 48 for the suspension of sanction
previously given by the plunging of the instrument at B is as follows:-
When the handle previously referred to is turned the metal segment 18 moves

page_text: upward and raises the spring 42, freeing the contact 44 from the spring 43 and
making contact with 49 allowing the current to flow from 49 through the
resistance to earth, maintaining the current in the magnet 25; this replaces the
arm 18 to "danger" and also the arm in the dial 7 of the instrument at A to
"danger" and allows the armature 9 to drop away from the magnet 8, breaks
contact at 10 and breaks contact in the apparatus on the signal post by
demagnetizing the magnet 106, Figure 6, allowing 103 to drop and 105 to drop
away clear of 100 on lever 98; this places the signal arm to "danger."
Upon a reversal of the switch to its normal condition it would make the contacts
previously broken and would deflect the semaphore arms in the indicators 18
and 7 and would again make contact in the apparatus on the post so that the
operation of its operating lever 11 would deflect the arm.
In order to make the operation of the switch 48 more perfect and that the
sanction previously given may not be suspended after the train has passed the
sectional signal and before it has arrived at the treadle, we have provided as
follows:-
87 is a battery, one end connected to earth and the other connected to a
contact 88, that upon the passing of a train over the treadle 5 at the point 89 it
makes contact with the point 88 and brings into circuit the battery 87; by this
means a direct current is sent through the wire 17, through spring 43 and making
contact with the wire 46, through the electro-magnet 47 goes to earth when the
suspension switch is in its worked position. The completion of this circuit
attracts the armature 54, makes contact with the point 55 and through the wire 6,
demagnetizes the electro-magnet 25 freeing the armature 31. The switch 48 is
now inoperative.
"
The treadle 5 is what we will describe as a "make and break treadle," and its
operation consists that normally the circuit is complete from A to B through the
wire 17, on either side of the treadle contacts being made by means of the
mercury 90 in the cup connecting the two points 91 and 92, Figure 10. Upon
the depression of the treadle by the train, the mercury cup is tilted, the mercury.
leaves the points 91 and 92, severs the circuit between A and B, demagnetizes the
electro-magnet 25, freeing the armature 31, and also frees armature at A and
replaces the starting signal arm to "danger at that section, and the mercury in
travelling to the end of the cup makes contact between the points 93, 94,
Figure 10, connecting 93 to the battery and from thence to earth, and 94 into the
same line wire 17, which action, should the switch 48 be in its worked position,
sends a current (opposite to that which travels from battery 20) through line
wire 17, contact 73, 74, to spring 43 which is now in contact with 45, and so
through the coils 47 to earth. The armature 54 would be attracted thereby short
circuiting magnet 25 and allowing armature 31 to fall away.
If the switch 48 is in its normal position the battery 87 would have no effect
when treadle 5 is depressed.
We will now describe that portion of our invention with reference to slip coaches
and analogous movements.
Figure 4 is a part longitudinal section of a slip coach, showing one of the known
methods of mechanical slipping. 78 is the mechanical lever which upon being
moved forward upon the segment 79, disconnects the couplings from the coach in
advance and thereby slips the carriage. Attached to this lever 78 is a connecting
link 80 connecting another lever 81 centred at 82 terminating in a brush 83. 84 is
one of the contact pieces hereinbefore referred to as 61, 62 and 64 65, fixed in the
four feet.
The action of this portion of our invention is as follows:-
:-
The guard in approaching the stop signal or the desired position at which he
intends the coach to slip, moves his lever 78 forward, slips the mechanical coupling
of the coach and moves the lever 81 and brush 83 into the dotted position. It will
be observed that there is an iuclined edge to the bar 84 to ease the movement of
the brush in travelling over it.

page_text: Figure 5 is a section of the contact piece 84, on either side there are metal
projections 85, 86. The prongs of the brush in moving over 84, which is made of
insulating material, connect the metal 85 and 86, complete the circuit through the
wires 63 and 66, excites the electro-magnet 57, draws the armature 58 into the
magnet, makes contact with the contacts 67 and 70, and the slot 59 is moved so
that its end is bearing upon the pin 60 on the click 32. By that means the click 32
is pulled, operates the magnet 57, and although the said click was previously
locked it maintains the lock on it and prevents the plunger 28 from being operated
to accept another train from the rear. The front portion of the train in proceeding
passes over the treadle 6, sends a current, which would under normal conditions
free the instrument by the armature 33 being drawn up to the magnet 35, the
click 32 is held, as previously described, to the magnet 57 thereby keeping the
instrument in its locked condition; when the slip coach has drawn up at the station,
so long as it remains upon the main line the signalman at B is prevented from
plunging a second time to accept a train from the rear. When the coach is backed
into the siding contact is again made by the brush being in the worked position,
that is to say, lowered, making contact and thereby short circuiting the battery 71,
freeing the armature 58 from the electro-magnet 57, allowing the click 32 to fall
by gravity, and also excites the electro-magnet 35, attracts the armature 33, and
by this means enables the signalman to plunge 28 and accept another train from
the rear.
Figure 6 illustrates one among many modifications that may be devised of our
apparatus fixed in the upright rod on the signal post, intermediate between the
balance lever and the arm.
In this figure 95 is the upright rod connected from the arm to the top of our
apparatus, 16 is our apparatus as referred to in Figure 1, 96 is the lower portion of
the upright rod connected to the balance lever and terminating in a bevelled
edge 97, 98 is a lever centred at 99 having a catch 100 at its lower end, and centred
to its lower end a friction roller 101 centred at 102. A pawl 103 is centred at 104,
terminating in a catch 105, 106 is an electro-magnet preferably of the long pull
type, permanently fixed to our apparatus by set screws or their equivalents 107, 108.
109 is an armature in connection with the electro-maguet 106, and connected to the
said armature is a rod 110 terminating in a loop 111 working about a pin 112 which
works with the pawl 103; a rod 113 is connected to the pawl 103 moving through
a guide 114, which maintains it in its vertical position. 115 is a hammer fulcrumed
at 116 and on the upper part of the hammer is a spring 117. A spring 118 is used
to keep the piece 119 in position. 120 is a pin fixed firmly to the signal post
itself, 121 is also a pin fixed permanently to the post, 122 is a slot in the apparatus
in which the pin works in the travel of our apparatus, and 123 is another slot
which works about the pin 120 when our apparatus is moved up and down. 124 is
the upper part of the rod, the lower part of which is 110, and which is practically
a continuous one from the pawl 103 to the detent 125 fulcrumed at 126, terminating
at its end in a spring click 127.
The working of this portion of our invention is as follows:-
The pawl 103 is shown normally in gear with the catch at the end of the lever 98.
In actual practice these two would be normally disconnected and this would be so
when sanction has not been given by the cabin in advance. Suppose that sanction
of the cabin in advance had not been given and the signalman in the cabin
operating the signal on which our apparatus is fixed were to move his lever
referring to the arm he would simply move upward the lower portion of the
upright rod 96, thrust aside, by means of the bevel edge acting upon the roller,
the lever 98, but the arm would not be deflected. Assuming that sanction has been
given by the cabin in advance 100 and 105 are still disconnected until the signalman
to which the signal applies moves his lever, making contact, when the pawl 103 is
moved upwards by means of the electro-magnet 106 being excited, the armature 109
being drawn in and the end 105 being drawn in contact with the catch 100 as
shown.

page_text: ;
Upon the signalman now completing the movement of his lever, the upright
rod 96 being held in position by its guide through the casting would force upward
the roller 101 and by that means the whole of our apparatus would move upward and
the upper part of the upright rod, the result being that the arm would be deflected,
and in moving upward, the pin 120 would move down the slot 123, operate the
piece 119, move upward the hammer 115, the face of the hammer would get caught
bebind the spring click 127, in this position the spring 117 would be pressed
against the pin 128. The object of this spring pressing against the pin 128 is
that when the armature is free and the spring click 127 moves away thereby freeing
the hammer 115, the spring 117 being in compression and moving into expansion
or away from the pin would tend to assist the initial movement of the hammer 115
returning to its normal position.
Assuming that the signalman does not replace the arm to "danger," when the
train arrives at the treadle in advance of the said signal upon breaking the circuit
at the treadle the electro-magnet 106 would be demagnetized, the armature 109
would drop half of its movement through the looped end or slot on the rod 110,
sufficient to release the click 127 from the hammer 115, the hammer would then
drop and striking the rod 113 would force the pawl 103 downward, the end 105
being thereby freed from the catch 100 on the lever 98; by this means the arm
would return to "danger" and remain in that position. 129 and 130 are the wires
. leading from the electro-magnet 106, 130 goes to earth and 129 goes to the
contact 10, Figure 2. It should be mentioned that in the falling of our apparatus
the piece 119 strikes the pin 120 and gets to its original position above the piece
ready for the next movement.
It is obvious that although we have described this portion of our invention in
⚫ connection with the sectional signal, yet if desirable it may be fixed upon any signal
where such signal is either required to be controlled from any other spot in addition
to being mechanically worked, or where such signal is required to be replaced to
the "danger" position by the passage of a train.
Figure 7 illustrates a signal post with our apparatus 16 fixed in the upright rod
: intermediate between the balance lever and the arm.
In Figures 8 and 9 is illustrated a treadle, the former a side elevation, the latter
a plan, showing double contacts. The pin 154 is rigidly attached to the rail, and
when a train passes over it it is depressed and acts upon the short ends 155 and 156
of the long levers 157 and 158, this tilts the cups 159 (only one of which is shown)
one of which is fixed at each end. One half of the treadle only is illustrated with
the cover removed; the other end of the treadle is similar. When the cup 195 is
moved contact is either made or broken according as the train is passing over the
treadle or not. One contact 91-92 is normally made and the other contact 93-94
is normally broken, the former being broken by the passage of a train over the
treadle and the latter being made.
Figure 10 illustrates the mercury cup in section with the double con-
tacts 91-92, 93–94.
In certain instances which will be bereinafter described and referred to, we arrange
⚫ contacts at the back of the disc or other signal levers (for the purposes of illustration
we illustrate them as attached to disc signal levers) in order that where trains are
to be shunted from the main line clear of the main line, that is to say, into a siding
or on to the other main line, the said contacts are provided so that on the return
stroke of the signal lever the instrument at the cabin to which the signal applies, in
this case at B, may be released in conjunction with the movement over of the
stop sigual lever to give authority to receive a second train from the section in
. the rear.
Figures 11 and 12 illustrate the special form of contact.
Figure 11 is an elevation of our contact in its box or case.
Figure 12 is a side view.
Figure 13 shows our contact operatively connected to the lever.
In these figures 141 is the lever, a disc signal lever in this case, 142 is the

page_text: connection from the lever to the slide 131, 132 is a click fulcrumed at 133 to the
slide 131, 134 is a metal spring, 135 is a contact above the spring, 136 is a spring-
retaining the click 132 in its normal position, 137 is the case itself, 138 is.
insulating material on the near side of the spring 134, 139 is an insulated rest for
the spring 134, 140 is a stop on the slide 133 preventing the click 132 from moving
in the direction of the lever.
The action is as follows:-
The lever 141 in moving forward operates the slide 131, the click 132 is moved
upward by the insulating material 138, and upon passing clear of 138 is returned
to its norinal position by means of the spring 136; no contact is made by this
movement. Upon the return stroke of the lever the click 132 strikes the insulation,.
forces up the spring 134 until contact is made with the contact 135, and that
movement completes a circuit releasing the instrument at B or at the cabin at which
the disc signal is operated from, and allows the signalman to plunge his instrument.
to receive another train from the rear.
Our further improvements consist in arrangements whereby trains or vehicles are
allowed to be shunted clear of the line upon which they arrive at any block section,
and the act necessary for clearing the line by the disposal of the train or vehicle,.
coupled with the movement of the stop signal for the particular line a second time,
releases the instrument without employing cancellation or releasing by means of a
key or other methods as now in general use.
Figure 14 illustrates an ordinary station or block section. The numbers adjacent
to the various signals and switches are intended to mean the operating levers in the
locking apparatus in the signal cabin set apart for the purposes of working the
several switches and signals.
143 and 147 are, respectively, the stop and starting signals on the down.
line, 151, 152 and 153 are respectively the starting, stop and distant signals for the
up line.
A train arriving, say, being signalled on from the section in the rear, 143
has been worked over and replaced, and on its return stroke, that is to say, on its.
being replaced to its normal position, it is locked in that position and cannot be
lowered a second time to pass a second train into the section until certain movements
of levers have taken place, which would under ordinary conditions dispose of the
train previously arrived. Assume that the first train has to be shunted into the
down siding, 145 operating the switches and 146 operating the disc signal have to
be worked over and replaced before 143 can be pulled a second time, the train
being now in the down siding 143 may be operated and, as previously described,.
143 must be moved before the instrument can be plunged to accept a train from the
rear. In the same manner, if the first train is required to be shunted from the
down to the up line clear of the way, instead of to the down sidings, the train is first
allowed into the station by 143 being moved and its signal deflected, said signal 143.
being replaced on the train entering the station, 148 and 149 respectively the
switches and the signals at the cross-over are moved, the train shunted across to the
up line, 148 and 149 replaced to the normal position; now 143 is free to be operated
a second time and such operation must take place before the instrument at B is free
to be plunged to accept another train from the rear. In a precisely similar manner
a train arriving upon the up line, 152 is deflected, the train passed into the section,
152 replaced to its normal position and locked there, it cannot now, that is to
say 152, be operated a second time until certain movements corresponding to the
movements described with reference to the down line have been performed, that is
to say, that 148 and 150 are moved to shunt the train to the down line, or if the
train is going through into the next section, 151 operating the starting signal must
be moved, the starting signal deflected and the starting signal replaced to "danger"
before 152 is free to be operated a second time. The same release of the starting
signal upon its respective home signal described with reference to the up line-
is also applicable to the down line and is a principle in this special interlocking.
Assuming the first train arriving in the station, being shunted into the down
siding, a second train being accepted from the rear, 143 deflected and a second.

page_text: train drawing up to the starting signal 147, we provide that the first train which is
in the sidings cannot be shunted out of the sidings while the second train is standing
under the protection of the starting signal. In like manner if the first train had
been shunted on to the up line through 148 and 149, the second train admitted into
the section and standing at 147, as long as 147 is at "danger" and the second train
standing at it, the first train on the up line cannot be shunted across to foul the
second.
Figure 15 illustrates the mechanism we employ for effecting the results, for
interlocking the levers in the manner described for shunting purposes and freeing
the instrument to enable the signalman to plunge for a second train from the rear.
In this figure the numbers 143 to 152ª represent the tappets attached to the
levers operating the signals and switches as previously described.
In the tappets 143, 144, 145 and 148, there are notches or recesses corre-
sponding in shape to the locks 143, 114, 145, 148. 143, 144, 147ª, 151ª,
and 152 are blocks obstructing the passage, under certain conditions, of the
forward movement of the tappets 143, 144, 147, 151 and 152 respectively.
143 is normally free to be pulled, upon 143 being pulled it deflects the down
stop signal admitting the train into the station on the down line, the notch in 143*,
Figure 15, thrusts aside the lock 143 and as the locks 143, 144, 145, 146, 147,
148 and 149 are all actuated by the same slide iron 156 all the locks are thrust
out, by the movement of 143", of their respective notches, and the square side of
the lock 146 is moved against the tappet 146*. The construction of the lock 143,
as will be seen in Figure 15, has a bevel projection or tooth attached to it which
is 143. Upon the return of 143" to the normal position it falls and the notch
in 143 comes in contact with or surrounds the tooth 143° and the tappet drops to
a lower level to what it was in its normal position, on its first movement the front
of the tappet being obstructed from being moved forward by the block 143ª;
143 is now locked on its return stroke and cannot be moved forward a second time
until some movement of another tappet has taken place which will force the tooth
or projection 143 underneath the tappet 143" thereby raising it to its normal level
free of the block 143d, such movement is given by working tappet 146, which, in
consequence of its bevelled shape when the lock 146 is home against it the
tappet 146 in moving over moves aside the lock 146, inserts the tooth 143
underneath the tappet 143" thereby raising the latter to its normal position, free of
the block 143%.
On reference to the diagram it will be seen that 146 in conjunction with 145 are
the levers necessary to shunt the train into the down siding, 146 being the last
lever worked, as it is obvious that the switches must release the signal, and 146*
must be returned practically to its normal position to get the full draft or
movement of the connecting slide 156 should 143* be attempted to be moved a
second time.
This explains the special mechanism consisting of movements of levers needed
before the stop signal 143 can be lowered a second time. The train having been
disposed of into the down siding by the movements of 145 and 146, 143 is free to
be moved a second time and consequently upon its being moved the signalman is
free to accept another train from the rear. To prevent the first train which has
been shunted into the down siding fouling a second train which has been accepted
by 143 being lowered and the train standing at the starting signal 147 it will be
seen on reference to Figure 15 that the movement of 143 from its normal position
forward thrusts out the lock 144 from the notch in 144, immediately the said
lock is thrust out the tappet 144 falls and is therefore locked, 143 is replaced, the
train is shunted through 145 and 146 is moved to give authority for such movement,
the working of the tappet 146* forward moves back the lock 144b and by means of
its tooth 144° raises the tappet 144" to its normal condition free of the block 144;
the first train is now in the down siding and if it is required to come out of the
down siding it is free to do so 144 being free to admit of its movement out of the
sidings. Should, however, a second train be accepted 143* is moved again to admi

page_text: it into the section and 144 through its tappet 144* is locked in the same manner as
described before, and the second train drawing up under the protection of 147 the
starting signal, 144 the signal out of the siding through its tappet 144 being
locked is prevented from being worked to signal the first train out of the down
siding to foul the second one standing under the protection of 147 the starting
signal.
Figure 16 is a side elevation of the locks attached to slide 156, referred to in
Figure 15.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we wish it to be distinctly
understood that we do not claim as novel the mechanical arrangements of inter-
locking as we are aware that there are existing means for obtaining the same.
result, but we claim the combination of electrical and mechanical interlocking as.
set forth in the following claims :—
1. In railway signalling apparatus, arrangements whereby the section in advance
controls the arm of the sectional signal in the rear instead of as hitherto controlling
the lever operating such signal, substantially as herein described and as illustrated
in the accompanying drawings.
2. In railway signalling apparatus, arrangements by which a treadle fixed at any
desirable spot, upon its operation by a train, replaces the arm in the rear in
connection therewith to the "danger" attitude, substantially as described and as.
illustrated in the accompanying drawings.
3. In block instruments for railway signalling apparatus, arrangements whereby
the operation of the switch suspends the authority previously given by operating
the plunger of the said instrument, substantially as described and as illustrated
in the accompanying drawings.
4. In block instruments for railway signalling purposes, arrangements whereby
when the signal has been suspended by the movement of the switch, the reversal
of the switch to its normal position makes operative the sanction previously given
by plunging, substantially as described and as illustrated in the accompanying
drawings.
5. In railway signalling, apparatus fixed intermediate between the balance lever-
and the arm whereby the arm cannot be deflected unless sanction has been received
from the cabin in advance thereby allowing the operating lever to deflect the said
arm, or making the operation direct to the apparatus on the post, substantially as.
described and as illustrated in the accompanying drawings.
6. In railway signalling, apparatus fixed upon the signal post by which after the
signal arm being once deflected it may be replaced by either its actuating lever, or
by the treadle fixed in advance, or by the signalman in advance operating his.
switch and so breaking the line current, substantially as described and as illustrated
in the accompanying drawings.
7. In railway signalling, apparatus fixed in the upright rod on the signal post.
intermediate between the balance lever and the arm, substantially as described and
as illustrated in the accompanying drawings.
8. In lock & block railway signalling apparatus, arrangements whereby a coach.
(or coaches) slipped from the rear of a train, does not while it remains on the main.
line or on the line upon which it arrived, free the section in the rear, such release.
only taking place when the coach or coaches has or have been shunted clear of the
main line, thereby releasing the instrument at that section allowing the man to.
plunge to receive another train, all substantially as described and as illustrated in.
the accompanying drawings.
9. In railway signalling apparatus, interlocking apparatus whereby the movement
of the operating levers giving authority for the movement of the train clear of the
line upon which it arrives and the replacing to the normal position of the said
levers releases the block instruments allowing the signal operator to accept a train.
B

page_text: from the rear, all substantially as described and as illustrated in the accompanying
drawings.
10. In railway signalling, the method described of releasing the block instruments
where trains do not proceed to the next section, all substantially as described and
as illustrated in the accompanying drawings.
11. In railway signalling, the combination of interlocking tappets, their operating
levers, the block instruments, contacts at the back of the levers, the treadles, and
the replacing apparatus fixed intermediate between the balance lever and the arm
on the signal post, forming a combined lock & block system, substantially as
described and as illustrated in the drawings annexed and for the purposes herein
set forth.
Dated this 29th day of June 1893.
JOHN P. O'DONNELL,
70 & 71, Palace Chambers, Bridge Street, Westminster, S.W.,
Agent for the said Applicants.