Improvements in Apparatus for Ensuring Safety of Traffic on Single Lines of Railway.
Year: 1891

page_text: Date of Application, 2nd Feb., 1891
Complete Specification Left, 2nd Nov., 1891-Accepted, 5th Dec., 1891
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Ensuring Safety of Traffic on Single
Lines of Railway.
I, EDWARD TYER, of Ashwin Street, Dalston, London, Electrical Engineer do
hereby declare the nature of this invention to be as follows:-
:-
In previous Specifications particularly No. 5928 of 1890 I have described
apparatus for ensuring safety on single lines of railway by electrically controlling
the issue from a station of a tablet to be carried by a train to a station beyond, this
tablet being a convenient substitute for the staff which a train usually carries with
it from one station to the next, so as to provide against more than one train being
on the section between those stations at one time. A set of the apparatus described
in these Specifications being established at each of two stations, and being suitably
connected electrically, no tablet can be issued from the apparatus at the one station
unless it is electrically released by the operator at the other station, and he does
not effect this release unless he knows that the section is clear, and he cannot effect
this release if he himself has already issued a tablet for a train proceeding to the
other station, unless that tablet shall have been received there. The object of my
present invention is to render apparatus of the kind referred to more simple in
construction and efficient in action.
I provide a disc which can be turned round a perpendicular axis by hand applied
to a knob or button outside a cover which covers the whole disc except. at one part
where there is a slit sufficiently large to insert edgeways through the cover or to
take out a tablet. In the disc itself there are a number of radial slots each capable
of holding a tablet inserted edgeways; and on the periphery of the disc or of a
wheel on the same axis with the disc there are two sets of ratchet teeth one tooth
of each corresponding to each slot of the disc the teeth of the two sets being sloped
opposite ways. The ratchet teeth of the one set are engaged by a spring pawl so
situated relatively to the slit in the cover that when a tablet is inserted the edge
of the tablet pushes the pawl out of gear, and at the same time disconnects the
battery circuits (thereby preventing any signals being sent from that apparatus)
the disc can then be turned one tooth in the one direction the pawl engaging again
when the tablet has passed from it; the battery circuits are thus re-connected and
the apparatus is put into its normal condition for either sending or receiving
signals. The ratchet teeth of the other set are engaged by a pawl which is released
by the armature of an electro magnet when that magnet is excited, and then the
disc can be turned one tooth in the other direction so as to bring a tablet to the slit
in the cover through which it can be taken out. This partial turning of the disc
opens the circuit of the electromagnet so that the pawl again engages and prevents
the disc from being turned more than the one tooth.
The slit by which a tablet can be inserted or taken out is provided with a cover
which, on being opened, locks the disc in position and prevents it from being turned
until the slit is closed again.
On the same axis with the disc and ratchets is a commutating wheel the
periphery of which is made with half as many rounded prominences and half as
many intermediate hollows as there are slots in the disc or teeth in each set of the
ratchets.
A roller mounted on a spring lever bears against the periphery of this wheel, and
this lever actuates springs, which, in one position of the roller, on the summit of a
prominence, make certain electrical contacts, and which in the other position of
the roller, in one of the hollows, makes other electrical contacts. These contacts

page_text: serve to close and open circuits including at each station a local battery, a polarised
relay, a signalling bell, the electro-magnet for operating the release pawl, a trans-
mitting key, a "switch" and a line wire connecting the two stations, so that the
issue of tablets is controlled in the following manner. Calling the operators at
the two stations A and B, and assuming that A desires to issue a tablet from his
apparatus to a train proceeding towards B's station, A signals to B his desire to issue a
tablet thereupon B, if the contacts and circuits at his station are in suitable
condition, by his transmitting key sends a current which excites A's electro-magnet
releasing the pawl. A can then turn his disc one tooth round so as to bring a
tablet to the slit in the cover through which he removes it but in thus turning his
disc one tooth, A has moved the roller.from a prominence to a hollow of his com-
mutating wheel or from a hollow to a prominence, and has thereby so altered the
condition of the contacts and circuits at his own station, that B's transmitter key
is rendered ineffective on A's electro magnet, consequently B cannot permit A to
issue a second tablet.
But when the tablet that had been issued by A is brought to B, he inserts it in
his disc and turns his disc one tooth round, thereby altering the condition of his
contacts and circuits so as to put them in such correspondence with A's, that he
can now use his transmitter key to permit issue of another tablet by A. In like
manner A can permit B to issue a tablet and when B has done so, A cannot permit
him to issue another until he, A, shall have received in his apparatus the tablet
already issued.
When A has issued a tablet permitting a train to enter the section towards B,
and afterwards to return to A the tablet can on the return of the train be inserted
again by A, into his apparatus, and the turning of the disc one tooth will restore
the apparatus to its normal condition. B can operate in like manner, when
required.
Dated this 2nd day of February 1801
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Ensuring Safety of Traffic on Single
Lines of Railway.
I, EDWARD TYER of Ashwin Street, Dalston, London, Electrical 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:-
In previous Specifications, particularly No 5928 of 1890, I have described apparatus
for ensuring safety on single lines of railway by electrically controlling the issue
from a station of a tablet to be carried by a train to a station beyond, this tablet
being a convenient substitute for the staff which a train usually carries with it
from one station to the next, so as to provide against more than one train being
on the section between those stations at one time. A set of the apparatus described
in these Specifications being established at each of two stations, and being suitably
connected electrically, no tablet can be issued from the apparatus at the one station
unless it is electrically released by the operator at the other station and he does
not effect this release unless he knows that the section is clear, and he cannot effect
this release if he himself has already issued a tablet for a train proceeding to the
other station, unless that tablet shall have been received there. The object of my
present invention is to render apparatus of the kind referred to more simple in
construction and efficient in action, as I shall describe, referring to the accom-
panying drawings.
Figure 1 is a perspective view of the tablet apparatus T with its electrical
indicator I and pair of spring plungers S¹ S², and above it the signalling bell or

page_text: gong G, established at a station which is in telegraphic communication with the
next station by a line wire.
Figure 2 is a longitudinal section of the tablet apparatus T.
Figure 3 is a plan shewing the slotted disc under the cover.
Figure 4 is a plan shewing the ratchet wheel below.
Figure 5 is a side view of the releasing magnet and pawl, and
Figure 6 is a diagram shewing the electrical connection.
The tablet apparatus with its releasing electro magnet and the electrical contact
arrangements are all contained within a casing T which can be locked against
access. Through the cover of the casing passes a vertical axis T with a knob by
which it can be turned by hand in either direction; also through the cover there
is a slot of sufficient size to admit a tablet T inserted edgeways with lateral
notches to admit the fingers in taking out or introducing the tablet, this slot being
covered by a hinged lid T³ which can be turned back to give access to the slot.
On the axis T within the casing is fixed a disc D having a number of radial
slots D each capable of admitting a tablet T² inserted edgeways, and below this
disc is fixed on the axis T'a wheel W which has projecting from its face a circular
bead Wfitting a notch in the tablet T, so that when a tablet T' is inserted through
one of the slots D', its lower edge rests on W with its notch enclosing the bead W
On the upper face of the wheel W project ratchet teeth W2 engaged by a dropping
pawl W Also at the edge of the wheel W there are ratchet teeth W engaged by
a spring pawl W. The ratchet teeth W2 and W correspond in number with the
slots D of the disc D, and are sloped in opposite directions, so that the one
pawl W prevents the axis T', the disc D and the wheel W from being turned
forwards, that is to say, in the direction of the hands of a clock, the other pawl W³
prevent them from turning backwards. The pawl Ws is cranked upwards and has
projecting horizontally from it a horn-W6, which coming in front of the tablet T
which may happen to be in the neighbouring slot of the disc D, prevents the disc
and wheel from turning backwards, even if the pawl W3 should leave the wheel
free so to turn. The disc D also has on the upper face of the boss, near the centre,
teeth D² corresponding in number with its slots D' and the lid T3 is made with a
tail which when the lid is opened, engaging between a pair of the teeth D² prevents
the disc D, wheel W, and axis T₁ from being turned in either direction, unless the
lid T is closed.
The spring pawl W3 has a piece of insulating material W7 bearing against a
contact spring We so that when the pawl is pushed back so as to be disengaged
from the teeth W₁ the spring W8 is moved out of contact.
The dropping pawl W3 is one arm of a bell crank lever, the other arm W of
which comes behind a lug M² projecting from the armature M' of an electro-
magnet M, so that when this electro-magnet attracts its armature, the pawl W³ is
lifted out of engagement with the teeth W².
Besides the disc D, which receives and contains a number of tablets and the
wheel W which operates as a ratchet, preventing the disc from being turned except
as determined by the pawls W and W, the axis T' carries a multiple cam C,
which operates as a commutator, having half as many prominences C and half as
many hollows C² between them as there are slots D' or teeth W or W. A
roller C³ on a lever C' urged by a spring bears against the edge of the wheel C, so
that as the wheel revolves the lever C is moved to and fro, moving contact
springs C C and C7 linked to the lever.
The electrical connections being arranged at the stations A and B as shewn in
Figure 6, to connect the line L, the earth E and a local battery P to the contacts
for the bell G and a relay R included in the bell case also for the indicator I, the
plungers SS, the electro-magnet M, and the contacts of the springs C³ C and C7
and W, the apparatus is worked as follows:-
Assuming that the signalman at A desires to issue a tablet to a train proceeding
towards B, A by several depressions of his plunger S¹ causes B's gong G to sound

page_text: the preconcerted signal, whereupon B can answer, and if his line connections, as
well as A's, are in suitable condition, can by depressing his plunger S', while A
depresses his plunger S, cause a current to be transmitted froin A's local battery P
through the coil of A's magnet M. The armature M being attracted, raises the
pawl W3, enabling A to turn his wheel W backwards, but only one tooth because
the roller C³ is moved by the partial revolution of C so as to break a contact at C³
thus opening the circuit of the magnet M, whereupon the pawl W³ falls, stopping
the farther movement of W. But A having thus been permitted to turn his wheel
one tooth has brought a tablet held in a slot of his disc D to a position under the
lid T³.
In coming to this position the tablet T pushes away the upper part of
the pawl W and breaks the contact of W8 thus cutting the local battery P out of
circuit with C³.
A now opening the lid T3 and thereby stopping any farther motion of the axis T',
can withdraw the tablet, whereupon the pawl W again engages with W and
contact at W8 is re-established.
When A receives a tablet, he can open the lid T3 and insert the tablet in the
slot of D immediately below the lid opening, but, by so doing, he pushes away W
breaking the contact at Ws which is not re established until A having closed the
lid T3 turns his wheel one tooth forwards thereby removing the tablet T to the
position T and thus allowing W to engage with the next of the teeth W¼, and W
to make contact, again. It is not until A has made this movement, bringing
his roller C³ to an elevation of C, B being in the same condition that communi-
cation by the contacts C5 C and C is re-established. The operations of B for
issuing and receiving a tablet are the same as those of A, causing like alterations
of the electrical circuits at both stations by the automatic action of the apparatus.
Thus when B permits A to take out a tablet, the act performed by A in taking it
out so alters the electrical connection with B that B cannot permit A to take out
Ja second tablet whereby a second train could be admitted on the section. But
when the, tablet that had been issued by A is brought to B, the section being thus
clear of the train which brings it, B by inserting this tablet in his apparatus can
-restore. the. electrical connection with A to the condition in which A can be
permitted by B to issue another tablet. Thus successive tablets can be issued
In some cases
for successive trains, but only when the section of the line is clear.
A has to issue a tablet permitting a train to go towards B to a yard or siding, this
train having however to return to A without reaching B. In such a case A, by
issuing the one tablet, debars himself from issuing another until the train returns,
whereupon he can, by inserting the tablet and turning his disc one division as
-described, restore his apparatus to its normal condition.
The disc D is slotted to receive a number of tablets which may be great or small
according to the conditions of the traffic requiring many or few successive trains to
proceed in one direction.
It is convenient to fix on the upper part of the axis T' an index T' pointing to
graduations on the flange T, so as to shew the operator the number of tablets
remaining in the disc D.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed declare that what I
claim in respect of tablet apparatus for ensuring safety of traffic on single lines of
railway, is :-
1. The combination on one axis within a casing having only one local opening,
of a disc with slots containing tablets, a double ratchet wheel having its one pawl
moved by an electro magnet, and its other pawl moved by insertion of a tablet
and operating a contact, also a multiple cam or commutator wheel with contact
lever, substantially as described.
2. In combination with a local battery, bell and relay, a pair of spring contact
plungers and indicator, a contact arranged to be broken by insertion of a tablet, a

page_text: set of contacts altered by the movement of the commutator, the electrical
connections of those parts with each other and with the line wire, substantially as
described.
Dated this 2nd day of November 1901
ABEL & IMRAY,
Agents for Applicant.