Improvements in or relating to Railway Signalling.
Year: 1899

page_text: Date of Application, 24th Mar.,
1899
Complete Specification Left, 23rd Dec., 1899-Accepted, 17th Mar., 1900
Improvements in or relating to Railway Signalling.
We, WILFRID SWANWICK BOULT, Civil Engineer, of 143, Beechcroft Road,
Upper Tooting, in the County of Surrey, and CEDRIC RANDAL BOULT, Merchant,
of H 11, Exchange Buildings, Liverpool, in the County of Lancaster, do hereby
declare the nature of this invention to be as follows:-
This invention comprises further improvements in systems of railway signalling
such as our magnetic system, for which Letters Patent Numbered 17041 of 1893,
11778 of 1894, 2282 of 1895, 8724 of 1895, and 20735 of 1895 have been granted
to us.
66
One of the improvements according to this invention consists in the provision
of economy switches or means for reducing the time during which the road
electro-magnets are energized. To effect this reduction we employ one or more
switches (which for distinction are herein referred to as
economy switches")
to be closed after the signalling switches have been operated and thus to complete
the energizing circuits of the various road magnets only a very short time before
the arrival of the train to be signalled. The operation of the economy-switches
may be effected in various ways either directly by the signal-men, or automatically
by the advancing train.
To work the economy-switch automatically we prefer the following plan. At
a suitable position on the line for the control of each block section, preferably
between the home and starter road-magnets, is placed a road armature (of the kind
described for "repeating" and other purposes in our above-mentioned specifica-
tions) the two circuit wires from which are connected with the coils of an indicator
in the contiguous signal-box, to show which circuit was last made. One or both
of these wires after passing through the indicator will be connected to a line wire
connected with the economy-switches in two signal boxes so arranged as to simul-
taneously break the circuit of the block section just passed by the train, and
close that of the section about to be traversed. Two magnets of opposite polarity
are carried by the train (or light engine),-one in front and one on the tail vehicle.
The indicator in the signal-box above mentioned, will show when these magnets
pass the road-armature: and the passing or not of the whole train is thus made
evident.
By means of a magnetic spring-switch, or equivalent device, actuated by current
flowing through the starter magnets and a shunt wire from beyond the contiguous
distant signal magnets it may be arranged that the starter magnets shall control
the distant signal magnets so that the "off" distant signal cannot be given by
the signal-man in advance, unless the starting signal is also off.
Instead of using automatic apparatus for operating the economy switches, we
may arrange these to be closed by hand, and opened by the breaking of the
magnet circuits by the signal switches. In this case there is no need of a separate
wire between the signal boxes, the magnet wire sufficing for all purposes.

page_text: An economy switch to be thus operated may be constructed as follows:-A
pivotted pendant iron tongue (which may itself be used as the switch and is herein-
after referred to as the switch tongue) and a tumbler iron tongue are connected
by a knuckle joint, so that when the tumbler is thrown, say to the left side, it
causes the switch tongue to complete the signalling circuit: and when thrown to
the right side tends to open this circuit. Three coils mounted on a common
iron base, to which also the knuckle joint pivot is connected through iron, are
placed one on each side of the tumbler and one on the right-hand side of the
switch tongue: the combination thus forming a non-polarized example of the
indicator movement described in our Specification No. 29257 of 1897. The left
hand coil is energized by a special circuit momentarily closed by the signal-man
working a key or plunger." The two right-hand coils are included in the
signal circuit through the road-magnets. The normal position of the tumbler
is hard over to the right, the signal circuit being then opened by the switch tongue.
Suppose now a train to be due on a block section A-B and signal switches in
position for giving the off signal as soon as the economy switch at A is closed.
As the train comes near, signalman A operates his plunger, the tumbler is thrown
to the left, and the economy switch closed. The signal current then flowing
through the two right hand coils seizes hold of the switch tongue and holds it
hard up, and throws the tumbler over to the right, as far as the knuckle joint
with the firmly held switch-tongue will allow. As soon as the train has passed
the signal box B the signal-man there opens the circuit A-B so as to set the
signals "on." Current in the economy switch coils at A then ceases, the switch-
tongue is released and thrown open by the tumbler falling a little further over
to the right-hand.
"
Another feature of this invention is the employment of "economy-switching"
for complete automatic block working. For this purpose we may use the following
arrangement: Just in advance of each block station we place a road armature
to be operated by two train magnets. as explained above and in connection with
these armatures are a series of two-point electro-magnetic switches for making
and breaking the signal-currents. These switches are preferably of polarized
constructions actuated similarly to the indicator " movement" above referred
to, consisting of two coils and a polarized switch arm. The operation of this
apparatus is as follows:-
As the front magnet of a train closes one circuit from the road-armature, the
contiguous switch is thrown so as to break the signal circuit of the block-section
just passed and to close a gap common to the rear end of the signal wire of the
block-section being entered and the second circuit from the armature. Or two
separate contact-making devices may be used instead of a common one. The
tail magnet of the train next completes the second armature circuit, whereby the
switch in rear of the one being passed is thrown so as to close the signal wire in
its rear. The action of the whole apparatus is as follows:-
The line is divided up by a number of block-stations A, B, C, D &c. The signal
wire of each block section has a gap at each end. A train passing C will by its
front magnet simultaneously put on the signals in B-C, close the rear gap of
C-D and prepare the circuit for taking off the signals in A—B, which operation
is completed by the tail magnet.
"
The signal currents" controlled as described, may be used for signalling on,
or to the trains by any known means as for instance by our magnetic method of
actuating signal indicators, &c. on the train, or by the movement of roadside
semaphores or lamp "spectacles."
Where constantly supplied current at comparatively high pressure is available
as from a dynamo or other source a convenient method of supplying the "sigual
currents" is by means of a conductor extending throughout a suitable number of
block-sections, with resistances inserted, where required, to cause drop of pressure,
so that "signal current" may be drawn off through conductors placed as a shunt
to any such resistance. With this arrangement current is always flowing along

page_text: the main conductor, but compared with the supposed source of supply the loss 01
power is insignificant.
The road-armature circuits may be supplied similarly or by batteries.
Our invention further relates to the employment of what may be termed a
magnetic-treadle."
This comprises an improvement on the plan outlined in the Specification of our
Letters Patent No. 17041 of 1893 where it is proposed to actuate roadside
apparatus by means of an iron plate carried by the engine, past road-magnets for
the purpose of deflecting a portion of the magnetic field so as to produce a move-
ment of a "striking-tongue" in the neighbourhood of the magnets.
Our present invention comprises a form of apparatus whereby a similar effect
is produced by the inductive action of the metal of the wheels of the rolling stock,
the apparatus thus being available for use without any special attachment what-
ever, on the rolling stock.
The form of apparatus we prefer,--which may be enclosed in a brass or other
non-magnetic case-comprises five main parts together with the necessary stops,
contacts, and electric connections. These five parts are:-A permanent magnet
(formed of one or more separate bars): two polar extensions (or pole pieces) of
iron or steel; a pivotted needle, also of soft iron or steel: a spring acting on the
needle in opposition to the pull of the magnetised pole-pieces. The magnet pole-
pieces and needle are so placed as to form a nearly complete magnetic circuit of
iron and steel: but small air-gaps are left to facilitate the demagnetising of the
pole-pieces and needle, when the wheel tyres pass by and collect a portion of the
field proceeding from the magnet, the instrument being placed in reference to
the stock-rail approximately in the position of a check rail.
The needle is furnished with contact arrangements for making or breaking
an electric circuit, being normally held against a stop with the circuit open by
the action of the magnet, the pull of which just overpowers the opposing pull
of the spring. When magnetism is "stolen" by a passing wheel the spring
pulls over the needle against a contact, so as to close the electric circuit, and
operate an indicator in the signal-box, or do other work as arranged.
It is not essential that this apparatus shall be constructed exactly as above
described for instance the pole-pieces may be dispensed with, a large air-gap
being left, or the ends of the magnet being bent round so as to come more or less
closely up to the needle; but practically we have found that the best action is
obtained in the manner stated, as great strength of field or flux from pole-pieco
to needle is produced, and can be very quickly reduced by the propinquity of
the wheel. To accentuate this feature of speed, we prefer that the cross-section
of the magnet shall be largely in excess of that of the pole-pieces which are
therefore densely magnetised, and similarly, that the cross-section of the pole-
pieces shall largely exceed that of the needle.
As this apparatus has to be placed within a few inches of the stock rail,
additional magnet power is required to compensate for the action of the rail in
permanently stealing magnetism.
In another form of magnetic treadle we use a long pivotted needle placed in an
approximately vertical position facing the inner side of the railway metal and
at such a distance from it (or below the surface) as to allow proper clearance for
the wheel flanges. The needle and its accessories may be enclosed in a brass or
other non-magnetic box, the needle itself being pivotted to an iron support or
bracket which projects through the back of the brass box. A permanent or
electro-magnet is placed with one pole close to or touching the iron bracket and
the other pole in proximity to the rail, on the same side as the needle or under-
neath or at the far-side. Two or more independent magnets may be used, and
the arrangement we prefer is to have two magnets bent round in a horizontal
plane one each side of the brass box and leading nearly up to the web of the rail.
The whole apparatus may conveniently be carried by a longitudinal timber
resting on the sleepers, but other arrangements of mounting may be used, such

page_text: as placing all the parts inside one non-magnetic box to be attached directly to the
sleepers. The needle may be pivotted directly to the magnet instead of through
the intervention of an iron bracket.
When no wheel is present an approximately balancing flux is established from
the upper half of the needle to the head of the rail and from the lower half to the
foot of the rail. By any suitable means, such as a piece of iron held in the space
between the foot of the rail and the needle or behind the upper part of the needle,
or by a spring, or by placing the needle so that its lower end is nearer to the rail
than the upper end is, the needle may be given a tendency to turn so that its
lower end shall approach and its upper end recede from the rail; such movement
being arrested by a suitable stop. In this the normal-position, the electric
signalling or other operating circuit, may be open.
When a wheel is present, the flange may project down directly between the
upper part of the needle and the rail head, thus greatly shortening the air-gap
and consequently causing a larger proportion of the total magnetic flux to take
this route. The pull between the upper half of the needle and the rail head is
thus augmented and that between the lower half of the needle and the foot of the
rail at the same time reduced, causing the needle to swing clear of the stop and
against the contact-post, as in the case of the treadle previously described. This
contact-making effect is heightened as a wheel passes, by the flange reaching from
opposite the needle to near the rail" end of the magnet, thus affording an
improved magnetic path between the magnet and the upper end of the needle
independently of the rail. When two magnets are placed as described, the latter
effect occurs first with one and then with the other as the wheel rolls past, making
the duration of this effect nearly twice as long as if only one magnet was used.
"
In a modification of the form of magnetic treadle above described, we provide
two gaps in the magnetic circuit and preferably, though not necessarily, place
the needles in an approximately horizontal position.
It is obvious that although the magnetic treadles have been described as working
upon the "open-circuit" system, yet they may without departing from the spirit
of this invention he adapted to work upon the "closed-circuit" system-that is
to say, the action of the passing wheel may open a circuit which is normally
closed.
We also provide a “treadle-indicator" for use in conjunction with the herein-
before described magnetic treadle. This preferably comprises a combination of
two step-by-step or ratchet movements arranged by means of epicyclic or equiva-
lent gear to move the same finger in opposite directions. The two movements
will be operated by two separate treadles, one at each end of a block-section. As
a train passes the first treadle each wheel operates the connected ratchet-movement
one step; the finger showing on a scale how many steps it has moved, that is,
how many wheels have passed the treadle. When the train passes the second
treadle a reverse movement of the indicating-finger takes place, and when the
whole train has passed the finger is again returned to its starting or zero position.
The parting of a train in the block-section would thus be indicated by the non-
return of the finger to zero.
As one treadle may indicate in two or more signal boxes, an average of one
treadle per block section will suffice for indicating the passing of trains all along
the line.
Dated thie 24th day of a 1000

page_text: improvements in or relating to Hallway signaling.
We, WILFRID SWANWICK BOCLT, Civil Engineer, of 143, Beechcroft Road,
Upper Tooting, in the County of Surrey, and CEDRIC RANDAL BOULT, Merchant,
of H 11, Exchange Buildings, Liverpool, in the County of Lancaster, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
This invention comprises further improvements in systems of railway signalling
such as our magnetic system, for which Letters Patent Numbered 17041 of 1893,
11773 of 1894, 2282 of 1895, 8724 of 1895, and 20735 of 1895 have been granted
to us.
"
One of the improvements according to this invention consists in the provision
of economy switches or means for reducing the time during which the road
electro-magnets are energized. To effect this reduction we employ one or more
switches (which for distinction are herein referred to as economy-switches")
to be closed after the signalling switches have been operated and thus to complete
the energizing circuits of the various road magnets only a very short time before
the arrival of the train to be signalled. The operation of the "economy-switches"
may be effected in various ways either directly by the signalman or automatically
by the advancing train. The chief characteristic of an " economy-switch"
according to this invention is that it is in the signalling circuit and while it can
be closed in any convenient manner it is opened automatically by the cessation
of the signalling current.
A convenient form of
economy-switch" comprises a pivotted pendent iron
tongue, (which may itself be used as the switch and is hereinafter described as
the switch tongue) and a tumbler iron tongue connected to the switch tongue by
a knuckle joint, so that when the tumbler is thrown say to the left side, it causes
the switch tongue to complete the signalling circuit, and when thrown to the right
side tends to open this circuit. Three coils mounted on a common iron base, to
which also the knuckle joint is connected through iron, are placed one on each
side of the tumbler and one on the right hand side of the switch tongue, the com-
bination thus forming a non-polarised example of the indicator movement
described in the Specification of our British Letters Patent No. 29257 of 1897.
This construction is hereinafter more fully described.
Another feature of this invention is the employment of "economy-switching"
for complete automatic block working. For this purpose the following arrange-
ment may be used:-Just in advance of each block station a road armature is
placed so that it is operated by two train magnets and in connection with
This armature are a series of two-point electro-magnetic switches for making
and breaking the signal currents. These switches are preferably of polarized
construction and are actuated similarly to the indicator movement above referred
to. They comprise two coils and a polarised switch arm. The complete scheme
of automatic block working is fully described with reference to one of the accom-
panying diagrams.
Our invention further relates to the employment of what may be termed
a "magnetic-treadle." This comprises an improvement on the plan outlined in
the Specification of our British Letters Patent No. 17041 of 1893 where it is
proposed to actuate road side apparatus by means of an iron plate carried by the
engine past road magnets for the purpose of deflecting a portion of the magnetic
field so as to produce a movement of a striking-tongue in the neighbourhood
of the magnets.

page_text: Our present invention comprises a form of apparatus whereby a similar effect
is produced by the inductive action of the metal of the wheels of the rolling stock,
the apparatus thus being available for use without any special attachment what-
ever on the engines or carriages.
The form of apparatus we prefer which may be enclosed in a brass or other
non-magnetic case-comprises five main parts together with the necessary stops,
contacts, and electric connections. These five parts are:--A permanent magnet
(formed of one or more separate bars); two polar extensions (or pole pieces) of soft
iron or steel; a pivotted needle, also of iron or steel; a spring acting on the
needle, in opposition to the pull of the magnetised pole-pieces. The magnet pole-
pieces and needle are so placed as to form a nearly complete magnetic circuit of
iron and steel; but small air-gaps are left to facilitate the demagnetising of the
pole-pieces and needle when the wheel tyres pass by and collect a portion of the
field proceeding from the magnet, the instrument being placed in reference to
the stock-rail approximately in the position of a check rail.
The needle is furnished with contact arrangements for making or breaking
an electric circuit, being normally held against a stop with the circuit open by
the action of the magnet, the pull of which overpowers the opposing pull
of the spring. When magnetism is "stolen" by a passing wheel the spring
pulls over the needle against a contact, so as to close the electric circuit, and
operate an indicator in the signal-box, or do other work as arranged.
It is not essential that this apparatus shall be constructed exactly as above
described; for instance the pole-pieces may be dispensed with, a large air-gap
being left, or the ends of the magnet bent round so as to come more or less
closely up to the needle; but practically we have found that the best action is
obtained in the manner stated, as great strength of field or flux from pole-piece
to needle is produced, and can be very quickly reduced by the propinquity of
the wheel. To accentuate this feature of speed, we prefer that the cross-section
of the magnet shall be largely in excess of that of the pole-pieces which are
therefore densely magnetised, and similarly, that the cross-section of the pole-
pieces shall largely exceed that of the needle.
As this apparatus has to be placed within a few inches of the stock rail,
additional magnet power is required to compensate for the action of the rail in
permanently stealing magnetism.
We also provide a "treadle-indicator" for use in conjunction with the herein-
before described magnetic treadle. This preferably comprises a combination of
two step-by-step or ratchet movements arranged by means of epicyclic or equiva-
lent gear to move the same finger in opposite directions. The two movements
will be operated by two separate treadles, one at each end of a block-section. As
a train passes the first treadle each wheel operates the connected ratchet-movement
one step; the finger showing on a scale how many steps it has moved, that is,
how many wheels have passed the treadle. When the train passes the second
treadle a reverse movement of the indicating-finger takes place, and when the
whole train has passed the finger is again returned to its starting or zero position.
The parting of a train in the block-section would thus be indicated by the non-
return of the finger to zero.
As one treadle may indicate in two or more signal boxes, an average of one
treadle per block section will suffice for indicating the passing of trains all along
the line.
In the accompanying drawings
Figure 1 is a diagram illustrating the employment of "economy switches"
according to this invention, the switches being operated manually in the signal
cabins.
Figure 2 is a diagrammatic front elevation showing one of the " economy
switches" drawn to a larger scale.
Figure 3 is a diagram illustrating the employment of "
in a system of automatic block signalling.
economy switches
"

page_text: Figures 4, 5 and 6 are respectively a side elevation, partly in section, a cross
section and a plan of one construction of magnetic treadle according to this
invention.
Figures 7 and 8 are respectively an end elevation and a plan showing diagram-
matically another construction of magnetic treadle also according to this inven
tion, and
Figures 9 and 10 are respectively a plan and a side elevation of a “treadle-
indicator" according to this invention.
Like letters indicate like parts throughout the drawings.
With reference first to Figure 1 A and B indicate signal cabins connected by
rails a which branch after passing the cabin B. On the track are placed starter,
distant, warning and home signals 6 6 6 and 63 respectively, each set of signals
comprising permanent magnets shown in the diagrain by single circles, followed
by electro-magnets indicated by double circles. The permanent magnets are used
to give the danger or on signals while the electro-magnets give the off signals
as has been fully described in the Specifications of our previous British Patents.
The various signal electro-magnets are connected by wires E E¹, Es to the signal
cabin A, galvanometers 1' being introduced into the circuits. It will be noticed
that the only connection between the signal cabins A and B is a wire con-
necting the listant warning and home signals. It may be remarked here that
the only apparatus shown in signal cabin B is that which concerns the section
between it and the cabin A.
In the signal cabin A are two "economy-switches" G. Each of these switches
comprises a magnetic base G¹ and three cores G G G each surrounded by a coil.
Between the two upper cores G and G a tumbler G5 works. This tumbler G³
is pivotted upon an iron pillar connected to the base G¹ and is provided with
a knuckle joint G. Pivotted to the same pillar is a pendent iron switch
tongue G7 provided with a contact G8 which when in the proper position makes
connection with a contact (upon the core G (Figure 2). When in this position
the coils surrounding the cores G³ and G+ are connected to earth through the
contacts G and G8 and the tongue G7.
"
"
"
The left hand coils, that is those surrounding the cores G3, of both the " economy-
switches are connected in series and are joined through a plunger H to a
battery H. The right hand coils of each of the "economy-switches are joined
in series and are connected in the one case to the middle point of the battery H¹
and in the other case to a spring-controlled switch arm which works in con-
junction with an electro-magnet J₁ in the starter signal circuit. A double-pole
switch J is interposed in the circuits of the right hand coils, and this switch is
used as a
veto "switch whereby the signalman if he sees anything wrong with
the train as it passes, can instantly veto line clear signals given by the man in
advance, without wasting time in communicating with him. J is a switch at the
end of the starter signal circuit working in conjunction with contacts J* which are
joined respectively to each end of the battery H¹. The switch J works between
two contacts connected respectively to the distant and the warning electro-
magnets, a resistance equal in value to the resistance of the distant electro-
magnet coils being inserted in the warning electro-magnet circuit.
The only apparatus which need be mentioned in connection with the signal
cabin B is a switch J5 connected to the signalling wire E3 and working in con-
junction with two contacts Jo which are connected respectively to the ends of a
battery J', the middle point of which is earthed.
The normal position of the tumblers G5 of the " economy switches" G is hard
over to the right, that is against the cores G³, the signal circuit then being
broken by the gap between the contacts G and G.
Suppose now that the line has to be cleared for a train approaching the
section A-B, the economy switches G will be in the opposite position to that
shown in Figure 1 and the signalling circuits consequently open. The signalman
at A moves the switch Js on to one or other of the contacts J thus switching in

page_text: the battery H¹ to the starting signal circuit E, which circuit is however not yet
complete owing to the position of the economy switches G. The signalman at B
by means of the switch J³ connects the battery J7 to the circuit containing the
distant, warning and home signal electro-magnets 6' 6 and 63. As the train comes
near, the signalman at A operates his plunger H and current passing through
the coils G throws the tumblers G³ of the economy switches G over to the left,
the gaps between the contacts Gs and G³ in the signalling circuits thus being
closed. The signalling circuits being thus completed current flows through the
right hand coils G³ and G of the economy switches G and consequently the switch
tongue G7 is held hard up against the contact G; at the same time the core G³
pulls the tumbler G over to the right as far as the knuckle joint Go and the firmly
held switch tongue G will permit (see Figure 2). The movement of the left hand
economy switch G also completes the starting signal circuit E through earth
and the current in this circuit flowing round the electro J¹ pulls over the tongue J
As soon
and cuts in the circuit E¹ and the distant sigual electro magnets 61
as the train has passed, the signalman at A breaks the starting signal circuit at
the switch J, thus putting the starting signals on and the current ceasing in the
electro-magnet J, the tongue J automatically returns and puts the distant signal
on. When the starting signal circuit is broken at J³ the current ceases to flow
through the right hand coils G³ and G of the left hand economy switch G
(Figure 1), the pendent tongue G7 is released and is thrown over by the tumbler G³
which it will be remembered was previously inclined towards and consequently
now falls over to the right. A similar action takes place in the right hand
economy switch G when the signalman puts on the warning and home signals.
This he does by opening the circuit at the switch J³ as soon as the train has passed
his signal switch.
The switch-tongue J determines whether the signalling current from cabin B
includes or not the distant electro-magnets. In the position shown current would
flow through these magnets and the wire E, this being only possible when the
tongue J is held over by current passing through the electro-magnet J' in the
starter signal circuit. When this electro-magnet is not energised the tongue J
is in electric connection with the wire E².
Figure 3 illustrates the application of " economy switching" to automatic
block working. Four block stations A B C D are shown and just in advance of
each of them is placed a road armature K, the tongue of which is deflected against
a contact K¹ by the front magnet of a train and against another contact K² by
the rear train-magnet. Each block station is provided with a two-point electro-
magnetic switch L comprising coils L' and L2 and a polarized tongue L³ mounted
upon a magnet L' the whole arrangement forming a polarized indicator movement.
The contact arm L³ is earthed and is in electrical connection with the coil L³.
The contact arm L³ works in conjunction with two contacts L5 and L which are
respectively the ends of the signalling circuits in front and rear of the block
gap
sections on each side of the station. Thus at the block station C the
the contact L5 and the corresponding end of the tongue L³ forms the front gap of
the signalling circuit of the section B-C while the gap between the contact L
and the tongue L³ constitutes the rear gap in the signalling circuit C-D.
between
The front contact K¹ of the road armature is connected to one end of the coil L',
the other end of that coil being joined to the coil L2 of the preceding block station
and to one pole of a battery M." The other pole of the battery M is joined to the
armature K. The contact K³ of the road armature is joined to the contact L,
that is to the signalling circuit of the next block section, the other end of this
circuit being joined through a battery M¹ to the contact L at the next station.
Suppose now a train to be passing the station C. Its front magnet makes
momentary contact between the armature K and the contact K¹. The coil L
is energized by current from the battery M and the tongue L is pulled over closing
the gap at Le that is the rear gap of the next block section C-D. Now the pre-
ceding train when a block section ahead of the station D will have thrown the

page_text: on.
"
tongue L3 at that station into the position shown in Figure 3, that is with the
gap L in the section C-D closed. Hence current will flow from the battery M¹
through the electro-magnets in the signalling circuit C-D energizing them and
taking the signals in that section "off." But pulling down the tongue L" in the
station will have another effect also, viz., it will break the front gap at L³ of the
signalling circuit B-C, the signals in this circuit being therefore put
When the rear magnet passes over the road armature at C, the road armature
makes contact at K and a current then flows from the battery M through the
contact K, contact L and pillar L to earth at station C, thence to coil L³ at
station B, and back to the battery M. The coil L³ at station B is thus energized
and the tongue L³ pulled down, thus closing the gap L5 in the signalling cir-
cuit A-B.
It will be seen that each train or engine as it comes up closes the rear gap of the
section in front of it, the front gap having been closed by the preceding engine or
train when a block length ahead thereof. Obviously if the front gap has not
been so closed no current can flow in the signalling circuit of the block section
which the train is about to enter and consequently its further progress is blocked
by the signals being against it.
The signal currents controlled as described may be used for signalling on or
to the trains by any known means, as for instance by our magnetic method of
actuating signal indicators etc. on the train, or by the movement of road side
semaphores or lamp "spectacles."
Where constantly supplied current at comparatively high pressure is available
as from a dynamo or other source, a convenient method of supplying the signal
currents is by means of a conductor extending throughout a suitable number of
block sections, with resistances inserted where required to cause a drop in the
pressure so that signal current may be drawn off through conductors placed as a
shunt to any such resistances. With this arrangement current is always flowing
along the main conductor but compared with the supposed source of supply the
loss of power is insignificant. The road armature circuits may be supplied
similarly or by batteries.
"
Figures 4, 5 and 6 illustrate one construction of magnetic-treadle" according
to this invention. N are permanent magnets laid side by side and separated by
small pieces of non-magnetic material N. They are enclosed in a box N2 of
non-magnetic material say brass and are contained in a recess in a block of wood N³
in proximity to the rail a. Curved pole pieces N are arranged at the ends of the
magnets N being supported upon a second block of wood No. These pole pieces N
terminate in pole tips or horns N and in the gap between these horns is a pivotted
needle of soft iron. A spring O' is attached to the side of the needle () and the
end of this spring 01 bears against an adjustable stop 0³.
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The magnetic field in the gap between the pole tips N is normally strong
enough to hold the needle O in the position shown in Figure 6, against the
action of the spring 01, but should a wheel P pass in proximity to the treadle
as indicated in Figure 5 part of the field is shunted" through the wheel and the
needle under the action of the spring 01 turns slightly and brings a contact 0³
which it carries, against a contact stop 0 thus completing a circuit.
needle and its accessories are enclosed in a box or casing № of non-magnetic
material and this box is let into a recess in the wood block No.
The
Another form of magnetic treadle is shown in Figures 7, and S. Here the
needle O is placed vertically instead of horizontally. It is pivotted in an iron
support 0 carried by two permanent magnets №8 arranged so that their outer ends
are in close proximity to the rail « nearly touching the web of the rail in fact.
When no wheel is present an approximately balancing flux is established from
the upper half of the needle to the head of the rail and from the lower half to
the foot of the rail. By any suitable means such as a piece of iron held in the
space between the foot of the rail and the needle or behind the upper part of the
needle, or by a spring or by placing the needle so that its lower end is nearer

page_text: to the rail than the upper end is, the needle may be given a tendency to turn
so that its lower end shall approach and its upper end recede from the rail such
movement being prevented by a stop 0º. In this-the normal-position, the
electric signalling or other operating circuit may be open.
When a wheel P is present, the flange projects down directly between the upper
part of the needle and the rail head thus greatly shortening the air gap and con-
sequently causing a larger proportion of the total magnetic flux to take this route.
The pull between the upper half of the needle and the rail head is thus
augmented and that between the lower half of the needle and the foot of the rail
at the same time reduced, so that the needle will swing clear of the stop and
against the contact O. This effect is heightened during the passage of the wheel
owing to the fact that the flange reaches from the rail end of the magnets N³ to a
point approximately opposite to the needle and thus affords an improved
magnetic path between the magnet and the upper end of the needle independently.
of the rail. This occurs of course in connection with each of the magnets No in
the arrangement shown in Figure 8 and hence the duration of time during which
the needle is deflected is considerable.
Obviously instead of two magnets No bent in a horizontal plane as shown one
magnet might be used and the free end of that magnet might pass under the rail
if desired.
Again in magnetic treadles according to this invention we may use two needles
say in a horizontal position, each needle being adjacent to a gap in the magnetic
circuit, which gap is diminished by the passage of a wheel.
Although the magnetic treadles have been described as working upon the "open
circuit" system they may of course, without departing from the spirit of this
invention, be adapted to work upon the "closed circuit" system, that is to say
the action of the passing wheel may open a circuit which is normally closed.
Figures 9 and 10 illustrate one form of treadle-indicator according to this inven-
tion. Upon a base R is carried free to rotate in supports R¹ a spindle R². Two
ratchet wheels 13 and R are mounted so that they may rotate freely upon the
spindle R and each of these ratchet wheels R R has attached to it a crown
wheel R. Between the crown wheels K5 and carried upon a cross arm Re of the
spindle R³ is a small wheel R' gearing with each of the crown wheels R. This
arrangement of wheels is one form of a well known epicyclic or differential gear.
The ratchet wheel R³ is driven by a spring-controlled pawl R8 carried at the
end of a pivotted lever R", the other end of which is attached to the armature R10
of an electro-magnet R". A spring R adjustably supported in a bracket R¹³
pulls the armature up and depresses the end of the lever R carrying the pawl
when the electro-magnet R¹s ceases to be energized. R is an adjustable stop
carried in a pillar R, its function being to limit the motion of the pawl Rs.
The ratchet wheel R is arranged to be driven in an exactly similar manner
to that described above with reference to the ratchet wheel R except that it is
driven from an electro-magnet R at the other end of the base R and is rotated
in the opposite direction. For the sake of clearness the armature, pivotted lever
and pawl in connection with the ratchet wheel R+ are not shown in the drawings.
The end of the spindle R carries a light pointer R" which may be arranged to
move over any convenient form of dial.
Any suitable contact making apparatus may be included in the circuit of the
electro-magnets R" or R, one of the forms of magnetic treadle described above
being very suitable for the purpose. One such treadle may be placed at each end
of a block section, each treadle being connected in circuit with one of the electro-
magnets and a suitable battery. Each wheel of a train as it passes over the first
treadle will actuate say the electro-magnet R and cause the ratchet wheel R³ to
be rotated through a distance equal to a certain number of teeth. The crown
wheel R rotates with the ratchet wheel R³ and through the wheel R' causes the
spindle R to rotate carrying the pointer R" with it. If the same number of
wheels pass over the second treadle electro-magnet R¹ is actuated and the ratchet

page_text: wheel R rotated for an amount exactly equal but opposite in direction to the
motion of the ratchet wheel It", consequently the pointer R is restored to its
original position. Such an arrangement is exceedingly useful for wheel-counting
or similar purposes. Obviously the mechanism could be arranged to be operated
say by a spring and controlled electrically.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:-
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1. In magnetic railway signalling the combination with a signalling circuit of
an economy-switch" closed in any convenient manner and opened automatically
by the cessation of the signalling current.
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2. In magnetic railway signalling an economy-switch" having a tumbler
and a pendent switch tongue substantially as described.
3. The complete "economy-switch" substantially as described or illustrated
in Figure 2 of the accompanying drawings.
4. In a distant and starting signal control system the employment substantially
as described of an electro-magnetic switch J J.
5. The system of "economy-switching" in railway signalling substantially as
described or illustrated in Figure 1 of the accompanying drawings.
6. The complete system of automatic block signalling substantially as described
and illustrated in Figure 3 of the accompanying drawings.
7. In railway signalling operating a needle or contact tongue by diminishing
the magnetic flux through it substantially as described one member of the
magnetic system being upon the moving vehicle and the other upon the road.
8. In railway signalling the employment of the wheels of the rolling stock to
deflect a needle or contact tongue by diminishing the magnetic flux through it
substantially as described.
9. In a
magnetic-treadle" the combination of two pole-pieces such as N' N
with a spring controlled pivotted needle such as O between them substantially as
and for the purpose described.
10. In a magnetic treadle" the combination of a vehicle wheel and two pole-
pieces such as NN with a spring controlled pivotted needle such as O between
them the needle being permitted to be operated by the spring when the strength
of the magnetic flux is reduced by the presence of the wheel.
11. The complete "magnetic treadle" substantially as described or illustrated
in Figures 4, 5 and 6 of the accompanying drawings.
12. In railway signalling a "magnetic-treadle" having an approximately ver-
tical needle, the ends of which act in conjunction with the head and foot of the
rail respectively substantially as described.
13. In railway signalling the combination substantially as described with a
* magnetic-treadle" of an indicator comprising electrically actuated or controlled
step by step movements geared together for the purpose described.
14. The complete "treadle-indicator" substantially as described or illustrated
in Figures 9 and 10 of the accompanying drawings.
Dated this 23rd day of December 1899.
BOULT, WADE & KILBURN,
Agents for the Applicants.