Improvements in Apparatus for Electrically Interlocking the Block and Mechanical Signals on Railways.
Year: 1899

page_text: Date of Application, 4th Jan., 1899
Complete Specification Left, 3rd Nov. 1899-Accepted, 23rd Dec., 1899
Improvements in Apparatus for Electrically Interlocking the Block
and Mechanical Signals on Railways.
We, LUIZ DE MORAES GOMES FERREIRA, of Olinda, Bolton Gardens, Kensal Rise,
Electrical Engineer, and HENRY JAMES PRYCE, of 54, Filey Avenue, Clapton, Civil
Engineer, both in the County of London, do hereby declare the nature of this
invention to be as follows:-
Our invention relates to railway signalling apparatus working on what is known as
the lock and block system, the object of our invention being to simplify the
construction of such apparatus and render it more certain in operation than hereto-
fore.
In carrying out our invention we make use of the following elements in combina-
tion with a block instrument of any ordinary or suitable construction using reverse
currents (and advantageously the block instrument of the kind described in the
Specification of our former Patent No. 5867 of 1895) and with the lever by means of
which the mechanical signal is operated, videlicet.
(1) A lock for the commutator handle of the block instrument the said lock
advantageously comprising a slotted plate having in it notches corresponding with
the different positions in which the said handle is to be held, a pawl or pivoted catch
adapted to engage with one or the other of the said notches and carrying two contact
springs designed to make contact with two fixed contacts (hereinafter referred to as
contacts Nos. 1 and 2) and each of which forms part of a separate circuit containing
a local battery; a hook for retaining the said catch in a normal position and which
hook is mechanically disengaged from the said pawl by the movement of the handle
or knob of the block instrument when moved in the required direction, and an electro-
magnet (hereinafter for convenience of description referred to as the commutator
lock magnet) which serves for controlling the movement of the said catch which forms
the armature of the said magnet.
(2) A polarized relay the movement of the armature of which is designed to effect
the opening and closing of a local battery circuit.
(3) A tappet sliding in suitable guides and connected with the signal lever so as to
move therewith, the said tappet being notched and having arranged in connection
with it a catch (hereinafter referred to as the tappet catch) which forms the armature
of an electro-magnet (hereinafter referred to as the lever inagnet) which is included
in the circuit adapted to be closed by the armature of the relay.
(4) A commutator hereinafter termed a "circuit changer" consisting of a series of
fixed insulated contact strips and of a rotating disc, or a sliding piece, carrying a
series of contact forks which bear upon the fixed contact strips and are designed to
vary the electric circuits as the disc is rotated, the said disc being mounted upon a
spindle connected by a crank arm with the signal lever so that as the latter moves
the commutator disc is rotated more or less to make the desired changes in the electric
circuits. The said disc is not fixed to the spindle but has springs, slots, or both,
arranged in connection with it in such a manner that after it has partaken of a certain

page_text: amount of movement it can remain at rest whilst the spindle makes a further
movement.
(5) A treadle or contact device upon the permanent way which is designed as a
train passes over it to close an electric circuit in which the commutator lock magnet
is included.
The manner in which the parts above enumerated operate will be indicated from
the following description
Assume there are three signal boxes indicated by the letters A, B, C and at A's box
a train is waiting to pass to B and thence on to C.
A by means of the usual bell asks B "is line clear" and, assuming it is, B replies
by operating his block instrument to shew "line clear" on A's instrument, the current
which is sent also passing through A's relay in such a manner that the circuit of the
battery containing A's lever magnet is closed (the circuit changer at A being in
position to allow this) whereby the tappet catch is lifted to unlock the lever of A's
starting signal so that A can pull the signal off to allow the train to proceed.
As the lever is pulled over the circuit changer is operated to reverse the direction of
B's battery current through A's relay thereby causing A's tappet catch to drop and
back lock the signal lever. A now signals to B "train entering section "and B replies
by placing A's needle at "train on line" the current which does this passing through
A's relay so that the armature or moving contact piece thereof is again attracted.
This movement, however, of the said relay armature does not in this case complete
the circuit containing the lever magnet as, owing to the movement of the circuit
changer the lever magnet is now in a circuit which includes the contact No. 1
herein before referred to. As soon, however, as the train has passed over A's treadle a
current is sent through the commutator lock magnet which lifts the commutator lock
armature and causes the closing of the two circuits through the contacts Nos. 1 and 2
the hook in connection with the said ar. ature at the same time falling into position
to retain the said armature in a raised position when the circuit of the commutator
lock magnet is again broken. The closing of the circuits through contacts No. 1 and
No. 2 completes the circuit of the local battery containing the lever lock and also the
circuit of another battery which includes the commutator lok magnet so that
after the circuit of the commutator lock magnet through the treadle contact is broken
the armature of the commutator lock will still be held up.
When the signal lever is thrown back to put the signal to danger the circuits
through the contacts Nos. 1 and 2 are broken, the armature of the commutator lock
dropping on to the hook and the tappet catch engaging to lock the lever.
"
B now signals to C in the same manner as A signalled to B and having pulled off
bis starting signal and received the signal from C "train on line cannot operate
his block instrument until the train has passed over his treadle.
It thus follows that it is not possible for a signalman in one box to clear back to
the preceding box until a train has been accepted by the signalman at the succeeding
box and has passed over the treadle of the intermediate box. In practice it is
immaterial whether a train passes over the treadle before or after the signalman in
the succeeding box accepts the train but in any case it is necessary that both the
acceptance of the train by the succeeding box and the passage of the train over
the treadle should take place before a signalman can clear back to a preceding
box.
In the foregoing description the tappet catch is arranged to normally lock its lever
and to be unlocked by the electric current, in some cases, however, for instance at
junctions it may be necessary that a lever should be normally unlocked and only
locked when a current is passed through the lever maguet, in this case the tappet
catch instead of engaging with notches on the top of the tappet will be formed with
a stirrup the cross bar of which will engage with notches on the underside of the
tappet when the magnet is energised.
In order to provide for cancelling a signal in cases where a signalman in a succeeding
box has accepted a train which, however, does not require to proceed and so does not
pass over the treadle, or otherwise, we make use of what we may term a contact box

page_text: in each cabin, each of which has two contacts one connected with a local battery and
the other with the commutator lock magnet circuit. The contact makers for use in
connection with these boxes are advantageously in the form of keys each of which
can be caused to make contact with either of two other contacts and which are
adapted to enter key-holes formed in the box. These key-holes are protected by a
sliding plate in such a manner that when one hole is opened the other is closed.
To illustrate the operation of the above supposing A has offered a train to B and
that B has accepted the train by shewing "line clear" upon the block instrument
and that A has pulled off the signal. A now requires to cancel this signal owing to
the fact that the train will not pass over his treadle; to effect this he communicates
with B that he requires to do this, B then puts his block instrument to "line
closed" and puts the key into the "sending "key-hole in order to send a current
to A whilst A puts his key into the "receiving" key-hole and makes contact with the
line wire the result of which is that the current from the local battery at B passes
through A's commutator lock magnet and lifts the armature thereof to complete the
circuits hereinbefore described for enabling the signal lever to be pulled back and the
commutator returned to the "line closed" position.
It is to be understood that no signal can be cancelled without the simultaneous
concurrence of A and B.
Dated the 4th day of January 1899.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.
Improvements in Apparatus for Electrically Interlocking the Block
and Mechanical Signals on Railways.
We, LUIZ DE MORAES GOMES FERREIRA, of Olinda, Bolton Gardens, Kensal Rise,
Electrical Engineer, and HENRY JAMES PRYCE, of 54, Filey Avenue, Clapton, Civil
Engineer, both in the County of London, 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 relates to railway signalling apparatus working on what is known as
the lock and block system, the object of our invention being to simplify the
construction of such apparatus and render it more certain in operation than
heretofore.
In carrying out our invention we make use of the following elements in combination
with a block instrument of any ordinary or suitable construction using reverse currents
(and advantageously the block instrument of the kind described in the Specification of
our former Patent No. 5867 of 1895) and with the lever by means of which the
mechanical signal is operated, videlicit,-
(1) A lock for the commutator handle of the block instrument the said lock
advantageously comprising a slotted plate having in it notches corresponding with the
different positions in which the said handle is to be held, a pawl or pivoted catch
adapted to engage with one or the other of the said notches and carrying two contact
springs designed to make contact with two fixed contacts (hereinafter referred to as
contacts Nos. 1 and 2) and each of which forms part of a separate circuit containing
a local battery; a hook for retaining the said catch in a normal position and which
hook is mechanically disengaged from the said pawl by the movement of the handle
or knob of the block instrument when moved in the required direction, and an electro-

page_text: magnet (hereinafter for convenience of description referred to as the commutator lock
magnet) which serves for controlling the movement of the said catch which forms the
armature of the said magnet.
(2) A polarized relay the movement of the armature of which is designed to effect
the opening and closing of a local battery circuit.
(3) A tappet sliding in suitable guides and connected with the signal lever so as to
move therewith, the said tappet being notched and having arranged in connection
with it a catch (hereinafter referred to as to the tappet catch) which forms the
armature of an electro-magnet (hereinafter referred to as the lever magnet) which
is included in the circuit adapted to be closed by the armature of the relay.
(4) A cominutator hereinafter termed a "circuit changer" consisting of a series of
fixed insulated contact strips and of a rotating disc, or a sliding piece, carrying a
series of contact forks which bear upon the fixed contact strips and are designed to
vary the electric circuits as the disc is rotated, the said disc being mounted upon a
spindle connected by a crank arın with the signal lever so that as the latter moves the
commutator disc is rotated more or less to make the desired changes in the electric
circuits. The said disc is not fixed to the spindle but has springs, slots, or both,
arranged in connection with it in such a manner that after it has partaken of a
certain amount of movement it can remain at rest whilst the spindle makes a further
movement.
(5) A treadle or contact device upon the permanent way which is designed as a
train passes over it to close an electric circuit in which the commutator lock magnet
is included.
In order to provide for cancelling a signal in cases where a signalman in a succeeding
box has accepted a train which, however, does not require to proceed and so does not
pass over the treadle, or otherwise, we make use of what we may term a contact box
in each cabin, each of which has two contacts one connected with a local (cancelling)
battery and the other with the commutator lock magnet circuit. The contact makers
for use in connection with these boxes are advantageously in the form of keys each of
which can be caused to make contact with either of two other contacts and which are
adapted to enter key-holes formed in the box. These key-holes are protected by a
sliding plate in such a manner that when one hole is opened the other is closed.
In the accompanying drawings,
Figure 1 is a diagrammatic view representing our improved apparattus fitted in
three consecutive signal boxes.
Figure 2 is an inside elevation of the lower portion of a block instrument shewing
the improved commutator lock and its fittings.
Figure 3 is a sectional side view thereof.
Figures 4 and 5 are views of details of the improved lock drawn to a larger
scale.
Figures 6 and 7 are views of the lock plate shewing it adapted to a single needle
instrument.
Figures 8, 9 and 10 are views of the locking plate and parts connected therewith
drawn to a larger scale and in different relative positions.
Figure 11 is a view illustrating the signal lever, notched tappet and catch and the
connection with the circuit changer.
Figure 12 is a vertical section drawn to a larger scale showing one form of tappet
catch.
Figure 13 is a sectional view at right angles to Figure 12.
Figures 14 and 15 are views similar to Figures 12 and 13 of a modified construction
of tappet catch.
Figure 16 is a sectional front elevation of the commutator or circuit changer.
Figure 17 is a section on the line 17-17 of Figure 16; and
Figures 18, 19 and 20 are views illustrating commutators for special purposes
hereinafter more particularly described.
Figure 21 is a diagrammatic view illustrating the application of the invention to
signal box having both "home" and "starter" signals.

page_text: Figure 22 is a front view of a lever lock magnet employed in the combination
shewn in Figure 21.
Figure 23 is a vertical section on the line 23-23 Figure 22.
Figures 24, 25 and 26 are views illustrating a modified construction of lever lock
magnet.
Figure 27 is a diagrammatic view illustrating means for enabling signals to be
cancelled by the co-operation of the signalmen in two adjacent boxes.
Figures 28, 29 and 30 are two elevations and a section respectively of the cancelling
box.
To facilitate the description we will first describe the novel features of the various
elements employed, afterwards explaining how they are connected up and used on
railways.
Referring to Figures 2 to 5 which illustrate our improved lock applied to a
commutator device of the kind described in the Specification of our former Patent
No. 5867 of 1895, a is the front of the block instrument, b is the commutator, b¹ the
commutator knob mounted on a spindle 62 carried in a bushing b³ fixed to the
front a of the case of the instrument; c is the hub fixed on the spindle 2 which said
hub has a slotted arm c¹ adapted to engage with the pin c² on the movable part of
the commutator which comprises the fork contacts 64, 65 (Figure 1); these forks
move over the fixed contacts 66, 67, 68, 69. All these parts are of the kind described in
our former Patent.
d is the indicator plate which is adapted to move in front of an aperture d¹, which
may be provided with a lens d2 as shewn, in the front a of the casing, the said
indicator being marked with coloured portions to indicate the various signals such as
"line closed," "train on line," "train passed treadle." This indicator plate d is,
however, not directly secured upon the spindle 62, as was the case in our said former
Patent, but is operated in the manner hereinafter described. e is the plunger the
stem e¹ of which slides through the spindle 62 and bears with its rear end against the
contact lever of the ringing key.
"
d³ is the slotted plate which is fixed to the flange or collar d upon the spindle 62;
and d³, d and d Figures 2, 4 and 8 to 10 are the notches which are formed in the
said plate and the two former of which correspond with the different positions in
which the commutator handle 61 is to be held whilst the latter d' is a safety notch to
prevent the commutator knob being only partially turned to the "train on line
position and then returned, the said notch d preventing the return.
ds is the pawl
or catch, the said pawl being pivoted at do and having a lateral pin d⁰ which is
adapted to engage in any one of the notches d³, do, d'; d¹¹, d¹² are the two contact
springs designed to make contact with the fixed contacts Nos. 1, 2, which form
part of separate circuits containing local batteries as hereinafter more particularly
described.
f, Figures 2, 3, 4, 5, 8, 9 and 10 is the hook for retaining the pawl d³ in the normal
position, the said hook being formed upon the lower end of an arm f¹ pivoted upon
a pin f2 fixed in the front a of the casing of the instrument and having a lateral pin fo.
This hook fis provided at its lower end with a notch f³ which forms the hook proper
and which engages with a lateral pin d¹³ upon the pawl lever or catch do when the
latter is operated by the commutator magnet, as is hereinafter described.
The hook fis controlled by an arm f4 which is pivoted at f³ to the casing and
which is formed with a tooth fo and a notch f' and also by a shoulder d¹ and a
pin d¹ upon the slotted plate d³ as will be understood later when the operation of
the apparatus as a whole is described.
f is the commutator lock magnet which controls the movement of the pawl
lever d³, a portion d¹ of which forms the armature of the said magnet. fo, Figures 2
and 3, is an arm upon the pawl lever d³ which said arm extends backwards towards
the front a of the instrument casing and engages with a notched arm 10 upon a
sleeve f¹¹ mounted upon a pivot pin f12, which sleeve f¹¹ also carries the indicator
plate d in such a manner that when the said pawl lever is raised or lowered the said
indicator plate is moved so as to present different signals behind the lens d² as
A

page_text: hereinafter described. The said plate d is divided as above mentioned into two
portions coloured respectively white and green which portions are presented before
the opening in the casing in conformity with the signals, as shewn in Figures 8 and
10. When the indicator plate is in the position shewn in Figure 9 the opening
shews red, this colour being upon a fixed plate do behind the said opening.
Figure 11 shews the tappet and commutator or circuit changer in combination
with the signal lever. We will first describe in detail the construction of the tappet
catch. This is shewn to a larger scale than Figure 11 in Figures 12 and 13 and
comprises the tappet g pivoted to the signal lever A and having the notches gº, g¹, g1
on its upper edge. This tappet g is adapted to slide through an eye or hole g², in
the lower end of a bracket g³ depending from a casing 94 95 is the catch proper
which extends down through the bracket g³ into the eye or hole 92 so that it can
engage with the notches go, g¹ in the tappet g, the upper end of the said catch proper
extending into the casing gt; the said upper end of the catch proper g³ has fitted
upon it the armature g of a magnet g suitably mounted in the casing gt. With
this arrangement when no current is flowing through the electro-magnet the tappet
catch g drops on to the lever g. In order, however, that a weak current shall
operate the tappet catch, the notches in the upper edge of the tappet 7 are So
arranged that when the signal lever is in its normal position the said tappet g
is advanced through the eye or hole 92 in the bracket g³ to such an extent that
the notched portion is beyond the tappet catch 95 so that the said catch normally
rests upon the plain upper edge of the tappet g. When, therefore, a current is
passed through the electro-magnet g7 the only work the said magnet has to do is to
retain the tappet catch g5 in its uppermost position, that is to say, to prevent it from
falling and not to raise it out of a notch. Should the lever be pulled when no current
is flowing through the magnet the tappet catch g5 immediately drops into the first of
the notches g' thereby preventing the tappet g from being pulled through the eye g²
farther than this notch; should the lever be pulled snfficiently to enable the first notch
g to escape the tappet catch go the said catch would fall into the second notch thereby
arresting the signal lever before it operated the signal; this second notch g¹ also
serves as a safety device to prevent the lever being used a second time for lowering
a signal before being put fully back to free the commutator lock as hereinafter
described.
In the arrangement illustrated in Figures 14 and 15, and which arrangement is
more particularly adapted for use with a lever controlling a "home" signal as here-
inafter described, the portion of the tappet catch g³ inside the casing g* is not
connected to the armature g of the electro-magnet 97 but is cranked or provided
with a shoulder g³, the portion go above the cranked part being provided at its upper
end with a pivoted pawl or catch y". A bridge g¹¹ is fixed to the bottom of the
casing g over the cranked portion of the catch proper g³, the height of the said
bridge being such as to allow the rise of the catch proper g³ flush with the upper
face of the hole g² so as to leave the tappet g free to pass through the said "hole.
The lower end of the armature go is bent outwards so as to form a stop which can be
passed between the lower face of the bridge 911 and the shoulder g8 of the catch g
thereby preventing the said catch from moving upwards and thus locking the tappet
lever g.
When the magnet is energized the armature is withdrawn from the bridge
so that the tappet catch g5 can rise under the bridge. The armature 9° is also
provided with a pin g12 by means of which it can be held from underneath the
bridge through the medium of the catch g10 when in its lowermost position.
Figures 16 and 17 are two views illustrating the commutator or circuit changer
which is employed in conjunction with the signal lever A. The said circuit changer
comprises a support or stand h in a bearing h¹ in which is mounted a spindle h²
adapted to be rocked by means of an arm h³ in connection, by means of a rod h*,
with an arm ho formed upon the lower end of the signal lever A as shewn in
Figure 11. i is the disc upon the spindle h2, the said disc being provided upon its
inner face with recesses in which extend projections upon a disc 22, springs 3
being interposed between the projections and the sides of the recesses 2º in the

page_text: plate i so as to form a spring connection between the two discs i and 2. The disc 12
is provided with slots of predetermined length within which extend projections 25
upon a disc j, j etc., are the contact forks (of which a suitable number
adapted to the particular apparatus may be employe.i) the said contact forks being
mounted upon an insulated block jo fitted to the disc i. k, k¹, etc., are the fixed
contacts which are mounted upon the insulating ring fixed to the inside of the
support or stand h of the commutator.
With this arrangement when the arm h³ is operated by the signal lever A, which
is moved in the usual way, the disc i is turned by the spindle h which through the
medium of the springs turns the disc 22 by means of the projections . The said
disc moves through a certain distance idly, that is to say, through a distance equal
to the lengths of the slots it after which, by the engagement of the projections 2³
with the ends of the said slots, the dise 2 is operited, thereby moving the contact
forks over the fixed contacts k until the stops on the disc 2 strike the stops i³
fixed to the casing of the device; further movement of the disc i is taken up by the
springs is
Referring now to the diagrammatic view shewn in Figure 1, representing our
improvements applied to three consecutive signal boxes A, B, C, we will describe the
method by which the signals are controlled by means of the apparatus.
"
A
Assume that a train is waiting at A's box to piss to B and thence on to C.
(whose commutator is locked at the "train on line" position) by means of the usual
bell asks B "is line clear" and assuming it is clear B replies by operating his block
instrument to shew line clear on A's instruinent. This he does by turning the
commutator knob 61 to the right (in the direction of the arrow indicated in Figure 8),
so as to bring over the slotted plate d³ to the limit of its movement in this direction,
that is to say, until the pin d10 comes into contact with the end of the slot in the said
plate d³.
This movement causes the shoulder d¹ of the plate d³ to raise the arm f¹
so that its pin fo is lifted into the notch f" to rest upon the tooth fo, thereby releasing
the pin d3 of the lever d³ from the hook f. The movement also turns the movable
part 64, 65 of the commutator b through the medium of the pin c² into the position
indicated in dotted lines in the diagrammatic view Figure 1. This movement of
the commutator 6 brings the local battery 1 into operation and current flows
from the said battery through the wire 3, through the commutator contact 66,
spring contact 64, commutator contact 60, wire 5, needle magnet 6, line wire 7,
to the needle magnet. 8 of A's instrument, thence through the wire 9 to the
contact of A's circuit changer, thence through the spring contact j2 to the fixed
contact after which it flows through the wire 10 to A's polarized relay m thereby
bringing the pivoted contact 11 against the fixed contact 12. From the polarized
relay m the current flows through the wire 13 to the fixed contact of the circuit
changer, thence through the spring contact 3, fixed contact 7, wire 14 to the earth
line 15, through earth to the earth line 15 of B's instrument, wire 16, fixed contact 67
of B's commutator, spring contact 65, fixed contact 68 and wire 17 back to the
battery 1. The closing of the contacts 11 and 12 completes the circuit of A's lever
tappet catch magnet 97, the current flowing from the local battery n through
wires 18, 19, contacts 11, 12, wire 20, wire 15, wire 21, fixed contact 3 of A's circuit
changer, spring contact j³, fixed contact le², wire 22, the magnet 7 and back to the
battery n. The armature go having the tappet catch g is thereby attracted so as to
unlock the lever of A's starter signal and enable A to pull the signal "off" to allow
the train to proceed on to the section between A and B.
As the lever is pulled over the circuit changer is operated to reverse the direction
in which B's battery current flows through A's relay (without altering the indication
of A's needle 8) thereby causing A's tappet catch to drop and back lock the signal
lever. This is effected as follows:-The movement of the lever turns the movable forked
The current from B's
contacts j,j, etc., into the positions shewn in dotted lines.
battery, therefore, flows in the following direction, that is to say, through wire 3,
fixed contact 60, spring contact 64, fixed contact 69, wire 5, need. 6, line wire 7 into
A's instrument through needle magnet 8, wire 9, fixed contact, spring contact ³,

page_text: fixed contact, wire 13, through the polarized relay m thus pulling the swinging
contact li over to the other pole of the said relay and breaking the contact between 11
and 12, the current flowing from the said relay through the wire 10, fixed contact k+,
spring contact j2, fixed contact ³, wire 21 and earth wire 15 back as previously
described to A's battery 1, the circuit containing A's lever magnet 97 being thereby
broken the tappet catch is dropped so as to back lock the signal lever.
A now signals to B "train entering section" and B replies by placing A's needle at
"train on line," the current which does this passing through A's relay so that the arma-
ture or moving contact piece thereof is again attracted. This is effected as follows; the
operator at station B turns his commutator knob b¹ back to its extreme position in
the other direction, that is to say, so that the pin d¹º drops into the lower notch d³ of
the plate d³ and the indicator d is swung down as shewn in Figure 9; this movement
brings the pin d against the arm f* and pushes the tooth from under the pin fo so
that the hook f is now held up by the contact of its lower end with the pin d¹³. The
rotation of the commutator knob turns the spring contacts 64, 65 into the position
indicated by the dot and dash lines in Figure 1, so that the current now flows as fol-
lows, that is to say, from the battery through the wire 3, fixed contact 6, spring
contact 65, fixed contact 67, wire 16, line 15 to earth along the earth line 15 of A's
instrument, wire 21, fixed contact ³, spring contact 12, wire 10, polarized relay m,
wire 13, fixed contact, spring contact j³, fixed contact 5, wire 9, needle 8, line wire 7
into B's instrument through needle 6, wire 5, fixed contact 6º, spring contact 64, fixed
contact 68, and wire 17 back to the battery l. This movement, however, of the said
relay armature does not in this case complete the circuit containing the lever magnet
as owing to the movement of A's circuit changer the magnet g7 is now in a circuit
which includes contact No. 1 herein before referred to. As soon, however, as the train
passes over A's treadle (which is here not shewn but which may be assumed to be
represented by the section of rail shewn at 0) a current is sent through the com-
mutator lock magnet f8 which lifts the commutator lock armature d¹6. The armature
is maintained attracted after the train has passed the treadle by means of a local
circuit from the battery p which flows as follows, that is to say, from the said battery p
through the wire 23, fixed contact k, spring contact j, fixed contact k³, wire 24,
fixed contact No. 2, spring contact d12, wire 25, wire 15, wire 26, commutator lock
magnet f, wire 27, back to battery p. With the current flowing in this manner the
spring contacts are held against the contacts Nos. 1 and 2, as above mentioned, after
the train leaves the trea:lle contact. The armature d¹ of the commutator lock
magnet when attracted by the said magnet brings the lateral pin d upon the
pawl lever up into engagement with the upper part of the notch d still locking
the plate din position at the signal "train on line," and moving the indicator d to
shew train passed treadle" signal as shewn clearly in Figure 10.
g
A can now return his lever to put the signal to danger and by doing so he breaks
the circuits through the contacts Nos. 1 and 2 thus causing the tappet catch g³
upon the armature of the magnet g' to drop into the notch upon the tappet lever
thereby locking the lever in its normal position; the breaking of the circuit at the
contacts Nos. 1 and 2 also causes the armature dio of the commutator lock magnet f
to drop thereby allowing the pawl lever d³ to drop, the said lever being held by the
catch on the arm f¹ in a position such that the lateral pin do upon the said lever is
held centrally in the slot of the plate d³ so that the commutator knob can be returned
to its normal position of "line closed."
B now signals to C in the same manner as A signalled to B and having pulled off
his starting signal and received the signal from C"train on line" cannot operate the
block instrument until the train has passed over his treadle as hereinbefore
described.
It thus follows that it is not possible for a signalman in one box to clear back to
the preceding box until a train has been accepted by the signalman at the succeeding
box and has passed over the treadle of the intermediate box. In practice it is
immterial whether a train passes over the treadle before or after the signalman in

page_text: the succeeding box accepts the "train entering section" signal but in any case it is
necessary that both the acceptance of the train by the succeeding box and the passage
of the train over the treadle should take place before a signalman can clear back to a
preceding box.
Figure 21 shews our improvements applied to a signal box having both "home"
and "starter" signals.
Assume the train is approaching B's box from A and that B desires to admit the
said train to the station platform in connection with which his box is stationed
although he has not received the signal from C that his line is clear. To admit the
train from A he has turned his commutator into the "train on line" position,
that is to say, so that the spring contacts 64, 65 occupy the position shewn by the dot
and dash lines in the figure and the slotted plate d³ that shewn in Figure 9 where it
is locked by the pin 10 on the pawl d³.
The lever magnet g7, which is of the kind described in Figures 14 and 15, has its
parts in the relative positions shewn in those figures, that is to say, such that the
armature is held out of engagement with the shoulder 98 of the catch g5 by means of
the small catch g10 so that the lever can be pulled out to lower the "home" signal to
admit the train into the station. This movement of the lever operates the circuit
changer of the "home" signals in such a manner that the movable contacts thereof
occupy the positions shewn in dotted lines in Figure 21.
When the lever is pulled the catch again drops and the armature is forced by the
spring go above the shoulder g³ thereof and under the bridge gll so as to back lock
the lever, the small catch 910 striking the stop g12 upon the armature and being turned
thereby into the position indicated in Figure 14.
The signal being down the train now passes up to the platform and in doing so
closes the first or "home signal" treadle contact and current flows from the battery p
through the magnet f³, wire 28, wire 29, earth, treadle contact, fixed contact o² of the
circuit changer, spring contact o³, fixed contact o*, spring contact of and wire 30 back
to the battery p. This current causes the commutator magnet armature to be
attracted so as to close the contacts Nos. 1 and 2 still locking the plate d³.
The closing of contact 1 allows current to flow from the battery through
contacts 0, 0, 015, 1, lines 28, 29, 33, magnet 97 back to battery n thus taking out
the back lock of signal which can then be put to danger. The circuit changer contacts
then resume the positions shown in full lines, the circuit through battery p, the
magnet, contact 2, contacts 04, 05 and 016 and line 30 being broken so that the
lever fails into the hook f³ and the commutator can then be replaced to its normal
position ready to receive another train from A; the home signal, however, remaining
locked until the train has passed the starting signal and second treadle.
The train is, however, stopped before the "starter" signal until the signalman in
box B has had his signal released by the signalman in box C. Assuming that this is
now done, as herein before described with reference to Figure 1, and that the
"starter" lever has been pulled to lower the signal, the circuit changer has been
moved so that its movable contacts occupy the position indicated by the dotted lines
in Figure 21, the train then passes over the second treadle contact and in doing so
closes the circuit containing the lever magnet g7 of the "home" signal so as to
attract the armature thereof and so free the lever by the catch glo dropping behind
the pin g and holding the armature out. The current in this case flows as follows,
that is to say, from the battery n, through the fixed contact o, spring contact o¹, fixed
contact o, wire 31, fixed contact 07, spring contact o", fixed contact 09,
wire 32, treadle contact and to earth wire 29, thence through wire 33, the lever
magnet g of the "home" signal and back to the battery n. The attraction of the
armature of the "home" signal lever magnet g7 closes the contact P (an example of
which is shewn in Figures 22 and 23) so that current can now flow through the
lever magnet g' of the "starter" signal thus attracting the tappet catch go thereof and
allowing the "starter" lever to be pushed back to its normal position; in this cise the
current flows as follows, that is to say, from the "starter" battery p¹, lever magnet 97,

page_text: wire 19, contact 12, contact 11, wire 29, wire 33, contact P, wire 34, fixed contact 010,
spring contact o¹¹, fixed contact 012, wire 35, fixed contact 013, spring contact of and
wire 36 back to the battery. As soon as the "starter" lever is pushed back to its
normal position the circuit is opened by the movement of the spring contact o" of the
circuit changer and the parts are all in their normal positions ready to receive another
train into the station in the manner herein before described.
Figures 18 and 19 respectively illustrate the arrangement of conticts for a
"starter" circuit changer as explained in connection with Figure 1 and for a "home
circuit changer as above explained.
Figure 20 illustrates a modified arrangement of sliding contacts for the circuit
changer, whereby the replacement of the "starter" lever completes the circuit
through the home lever lock magnet (7, Figure 21) thus dispensing with the use
of a second treadle. This is effected by the spring z pivoted on the spring z¹,
so that when the lever is being pulled z¹ and z are together on the contact 23
which is a dummy but when the lever is being replaced ¹ is on 22 before =
leaves thus completing a circuit between 22 and which takes the place of
wire 31, contacts 07, 08, 32, and treadle for freeing the home lever lock; 25 is
another spring not normally in contact with 24 but which by the pressure of a
key inserted through a hole in the cover of the circuit changer may be brought
into contact therewith and also by turning into contact with the spring 21 thus
completing the circuit as if the lever had been moved as might be required if the
train were shunted and the "starter was not used.
"
In the foregoing description of Figures 14 and 15 the tappet catch is arranged to
lock its lever and to be unlocked by the electric current, thereafter remaining un-
locked until used again. In some cases, however, for instance at junctions or sidings,
it may be necessary that a lever should be normally unlocked and only locked when
a current is passing through the lever magnet. In such cases we can employ a lock
magnet of the kind shewn in Figures 24, 25 and 26. r is a magnet which is
mounted in the usual manner in the support and 2 is an armature which is
mounted upon
the support 1 by means of a spring; the said armature carries
at its lower end a pin 4 which is adapted when no current flows through the magnet
to be passed under a bridge fixed to the magnet support and carrying at its upper
part a pivoted catch. This catch has a pin 7 at its lower end of the same size
as the pin upon the lower end of the armature and when uo current is flowing
through the magnet the armature pin comes into contact with the pin upon the
When the
catch and tuns the said catch to the position indicated in Figure 24.
parts are in this position the tappet catch in connection with the signal lever can
be pressed upwards as it is provided at its upper part with a notch r³ of such a size
that it can pass over the two pins 1, 77, so that the lever is normally unlocked.
When, however, the current is passed through the magnet r the armature is attracted
thereby allowing the catch to drop with its lower end under the bridge so that
the tappet catch can no longer be raised owing to the fact that the said lower end
of the catch is broader than the upper part of the notch in the said catch so
that the signal lever is now locked. When used for controlling a "home" sigual as
herein before described with reference to Figure 21 this arrangement can be provided
with contacts disposed as shewn in Figures 22 and 23.
Figures 27, 28, 29 and 30 are views illustrating the cancelling device and the
method of connecting it up in practice. Referring first to Figures 28, 29 and 30
which illustrate the device, q is a casing having a cover q¹ with a sliding lid q² which
can be moved so as to uncover one of two key plugs q, q. Each of these plugs carries
a circular insulating disc q5 having a segment qe thereon made of conducting material
and adapted when the keys are inserted to turn the plugs q, q to move the said
conducting portion q" over contacts q', q, q', in connection with each of the plugs.
Each of these contacts 97, 98, 92 are fixed upon an insulating insertion q¹ fixed in the
१ the said contacts being connected with the line wires in the manner indicated
in Figure 24.
box

page_text: The instrument is operated as follows:-
Supposing (Figure 27) B has offered the train to C and that C has accepted the
train by shewing "line clear" upon the block instrument and that B has pulled off
the signal. B now requires to cancel this signal owing to the fact that the train is
to be shunted, for example, so that it will not pass over his treadle; to effect this he
communicates with C that he requires to do this, and C then puts his block instru-
ment to "line closed" and puts the key into the "sending" key-hole in order to
send the current to B whilst B puts his key into the "receiving" key-hole and makes
contact with the line wire the result of which is that the current from the local
battery at C passes through B's commutator lock magnet and lifts the armature
thereof to complete the circuits hereinbefore described to enable the signal lever to
be pulled back and the commutator returned to the "line closed" position. The
current flows in the following manner, that is to say, starting from C's local battery s
through the contact spring q', contact spring q', wire 38, wire 39, line wire 40
between B and C, wire 41, spring contact q' of B's instrument, spring contact q³,
wire 37, commutator lock magnet f³ to earth thence to C's earth wire and back to
the battery 8. In the same way B could unlock C's commutator.
Although we have described our apparatus as applied to a block instrument of the
kind described in our former Patent No. 5867 of 1895 it will be understood that the
invention is also applicable to any known form of block instrument including single
needle instruments. In the latter case the slotted plate d³ can be secured to the
commutator spindle 62 in either of the positions indicated by the letters E, E¹ in
Figure 6. Figure 7 is a front view of the plate as arranged for a single needle
instrument.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In apparatus for electrically interlocking block and mechanical signals on rail-
ways, the employment of a commutator lock comprising a notched slotted plate, a
pivoted catch carrying two contact springs and the armature of an electro magnet
forming part of a local circuit, a hook for retaining the catch in the normal position
and a gravity arm for controlling the hook, substantially as herein before described and
illustrated in the accompanying drawings.
2. In apparatus for electrically interlocking block and mechanical signals on rail-
ways, the employment of a lever lock comprising a notched tappet, and a tappet catch
in connection with the armature of an electro-magnet, substantially as herein before
described and illustrated in the accompanying drawings.
3. In apparatus for electrically interlocking block and mechanical signals on rail-
ways, a circuit changer comprising a series of fixed insulated contact strips, a rotating
dise or the equivalent having a series of contact blocks bearing upon the fixed contact
strips and means for rotating the said disc from the signal lever, substantially as
hereinbefore described and illustrated.
4. The commutator lock herein before described and illustrated in Figures 2, 3, 4,
5, 6, 7, 8, 9 and 10 of the accompanying drawings.
5. The lever locking devices herein before described and illustrated respectively in
Figures 12, 13, 14, 15 and 22, 23, 24, 25 and 26 of the accompanying drawings.
6. The circuit changer herein before described and illustrated in Figures 16, 17,
18, 19 and 20 of the accompanying drawings.
7. In apparatus for electrically interlocking block and mechanical signals on rail-
ways the employment of the means for cancelling signals consisting of the parts
constructed, combined and operating, substantially as herein before described and
illustrated in Figures 27 to 30 of the accompanying drawings.
8. In apparatus fer electrically interlocking block and mechanical signals on rail-
ways the combination with a block instrument of a signal lever, of a commutator

page_text: lock, a polarized relay, a lever lock, a circuit changer and a contact device upon the
permanent way, substantially as, and for the purpose, hereinbefore described.
9. Apparatus for electrically interlocking the block and mechanical signals on rail-
ways constructed substantially as hereinbefore described and illustrated in the accom-
panying drawings.
Te and day of November 1800
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.