Improvements in Signalling Apparatus for Railways.
Year: 1896

page_text: Date of Application 19th Sept., 1896
Complete Specification Left, 21st June, 1897-Accepted, 7th Aug., 1897
PROVISIONAL SPECIFICATION.
Improvements in Signalling Apparatus for Railways.
I, LEICESTER BRADNEY STEVENS of Darlington Works, Southwark Bridge Road, in
the County of London, Engineer, do hereby declare the nature of this invention to be
as follows:
The object of this invention is to provide economical and effective means whereby
railway semaphore or similar signals may be operated by electricity. To this end I
mount the spindle, upon which the signal arm turns, in anti-friction bearings, such
for instance as roller or ball bearings. I then arrange to use the comparatively short
but powerful field of a common horse shoe electro magnet or magnets, (in preference
to using a long pull magnet) which, when energized by an electric current, attract
the armatures, which in turn communicate a differential pull to the signal arın by
wire, rod, or chain, which, as the case may be, pulls or pushes said arm and, overcoming
gravity, places it in the "safety" position. At this point one of the moving
parts of the device breaks the circuit energizing the operating magnet or
magnets, and almost instantaneously makes a second electric circuit which energizes
an electro magnetic brake or clutch so disposed as to retain the arm in said "safety"
position. Both these circuits depend upon a relay operated directly from the signal
box or other desirable point on the railway, so that when the said relay is de-energized,
both the operating and clutch magnet circuits are broken, and the clutch, releasing
the mechanism, allows the parts to return to their normal positions by gravity, and
consequently the signal flies to the "danger" position.
In one form of my invention I connect the armatures of two or more operating
magnets in tandem directly with the signal arm, in such manner that the armature
of one magnet is nearer the poles of its magnet than is the case with another
armature. All the armatures except one have either a flexible or yielding connection
with their cominon signal connection, whereby one armature arriving at its poles does
not arrest the progress of the others. This being the case, the first named armature,
being more within the magnetic field than the second named, takes the brunt of the
work at the commencement of the stroke. Thus I overcome the comparatively weak
pull exerted by a single magnet at the commencement of the stroke, on account of
the well known differential pull.
In another form of my invention I use either a single magnet or two or more
magnet's connected in tandem as before explained, but I interpose a pair of levers
between the magnet armatures and the signal arm, such levers having a differential
cam connection with one another so as to counteract to a large extent the uneven
magnetic pull. The armatures are connected to one of these levers and the other
lever is' connected to the signal arm. The great advantage of this arrangement is
a minimum at the
that the power needed to overcome gravity is reduced to
commencement of the stroke, and when the double lever gear places the magnet at
less advantage as regards leverage, this is more than compensated by the gain in
magnetic power in a geometric ratio; and also by the momentum of the signal arm
owing to its peculiar form.

page_text: The aforesaid magnetic relay for controlling the position of the signal I also utilize
to prevent the signal arm from being placed in the safety position accidentally or
maliciously. To this end I make the armature of the said relay engage with a
projecting portion of the signal arın or the parts attached thereto. This engagement
takes place by gravity, when the relay magnet is de-energized, and is freed just
before the relay completes the operating circuit.
Dated this 19th day of September 1896.
I, LEICESTER BRADNEY STEVENS, of Darlington Works, Southwark Bridge Road, in
the County of London, 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:-
The object of this invention is to provide economical and effective means whereby
railway semaphore or similar signals may be operated by electricity. To this end I
mount the spindle upon which the signal arm turns in anti-friction bearings such, for
instance, as roller or ball bearings. I then arrange to use the comparatively short
but powerful field of a common horse shoe electro-magnet or magnets (in preference
to using a long pull magnet) which, when energised by an electric current, attract the
armatures, which in turn communicate a differential pull to the signal arm by wire
rod or chain which, as the case may be, pulls or pushes said arm and, overcoming
gravity, places it in the "safety" position. At this point one of the moving parts of
the device breaks the circuit energizing the operating magnet or magnets, and almost
instantaneously makes a second electric circuit which energises an electro magnetic
brake or clutch so disposed as to retain the arm in said "safety" position. Both
these circuits depend upon a relay operated directly from the signal box or other
desirable point on the railway, so that when the said relay is de-energised both the
operating and clutch magnet circuits are broken and the clutch releasing the
mechanism, allows the parts to return to their normal positions by gravity and
consequently the signal flies to the "danger" position.
Referring to the accompanying two sheets of illustrative drawings:-Fig. 1 is a
side elevation of a semaphore signal provided with an electro-magnetic operating and
controlling apparatus arranged according to this invention. Fig. 2 is an end elevation
of the lower part of the same; and Fig. 3 is a side elevation to an enlarged scale, of
a modified arrangement of signal operating and controlling apparatus.
Referring to Figs. 1 and 2 the signal arm a is mounted on a spindle b working
in suitable bearings and carrying a drum or enlargement c around which a chain d
works, one end being secured to the said drum while the other end is secured to a
rode as shown, so that when a sufficient pull is applied to the said rod the arm a
is lowered into the "safety" position, shown in dotted lines, the removal of the
tension allowing the arm to be returned to its normal or danger position by gravity
in the usual manner.
The rod e passes through the two armatures f g of motor magnets hi and is so
connected to them by means of nuts lm that a differential action is produced by
them, that is to say, the armature g is normally much nearer to the poles of magnet i
than is the armature f to the poles of the magnet h by which means the magnets
act successively on their armatures thereby exerting a long pull on the rod e.
The motor magnets are connected in shunt parallel through battery A and contacts no

page_text: and when the circuit is closed and armatures fg attracted the arm p is attracted by
the magnet q in the main circuit causing the contact arm r to open the contact no
and break the shunt eircuits and thereby demagnetize the motor magnets hi
while the arm p locks the armature f until the main circuit is broken, when the
arin a. being free, returns to its normal position by gravity, the armature f being
raised and sliding out of engagement with the arm p in consequence of their
bevelled ends as will readily be understood; the disengagement being further
assisted by means of a roller in arm p.
On the spindle b of the arm a is mounted a cam in which the end of an
extension arm v of the armature w pivoted at x normally engages so as to prevent the
arm a being lowered accidentally or maliciously.
The action of the apparatus is as follows:-
In order to lower the signal arm a to "safety" a relay circuit is closed by
switch y through magnet z which attracts its armature w so as to make contact
with terminal ab and thereby close the main circuit, the end of the armature at
the same time being disengaged from the cam t and thereby freeing the signal
arm a. Current then flows through magnets hiq armatures fg being attracted
and pulling signal arm a down, the arm p, being also attracted by the magnet q
locks the armature f in its downward position while the arm presses on and
displaces contact plate o and breaks the circuits of motor magnets hi. The main
current however continues to flow through magnet q which attracts armature p,
the signal arm being thereby locked in its "safety" position, until the relay circuit
is broken by opening switch y when the relay armature w is released and breaks the
main circuit, the armature being freed of the arm p and permitting the signal
arm a to return to its normal position of "danger," in which position it is locked by the
arin vand cam until the relay switch y is again closed for another lowering of
the signal arm.
In the modified arrangement shown in Fig. 3 the motor magnets and their
armatures are mounted and connected to the pull rod similarly to those shown in
Figs. 1 and 2, but instead of the pull rod being connected to a chain secured to and
passing round a drun on the signal arm spindle it is connected to a double armed
swaying lever (not shown) also mounted on the signal arm spindle, while a second
rod a c is connected to the other arm and to a slide ad working in guides ae and
provided with a slot into which the hooked end af of the lever armature a g of a
relay magnet a h is capable of engaging so as to normally prevent the removal of the
signal from its "danger" position. On closing the controlling relay switch y the
magnet ah is energized and attracts its armature a g, disengaging the hook af from
slide ad while the pin a á, pressing on plate a l, causes it to make contact with
plate am thereby closing the circuit through the motor magnets hi and magnet q. The
slide ad being free and the motor magneta i energized, the armtures fg are
attracted pulling down the signal arm to its "safety" position when the lever armature p,
being clear of the armature f, is attracted by its magnet 9 and locks the said armature
and the signal arm in the downward positions. The motion of the armature causes
the pin r to press against the plate o and break contact between it and the contact
screw n, thereby breaking the circuit through the motor magnets. As however
current continues to flow through magnet q the armature continues to be attracted,
locking the signal arm until the relay switch y is opened to break the controlling
relay circuit, when the upward pull by the signal arm on the rod e causes the roller a
in lever p to run down the inclined path an on the armature f, which is thereby
disengaged, allowing the signal arm to return to its normal or "danger" position the
hook af at the same time engaging with the slide a d and preventing the lowering
of the said arm until the relay switch y is again closed.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is:-
1. A signal controlling and operating apparatus comprising motor magnets acting
differentially on armatures connected to the signal arm, means for locking the signal

page_text: arm in either the danger or safety position and a relay for controlling the motor
magnet and locking circuits, the whole substantially as described and for the purpose
set forth.
2. In a signal controlling and operating apparatus; motor magnets acting
differentially on armatures connected to the signal, in combination with a combined
locking armature and circuit breaking lever operated by a magnet in the main circuit
to break the motor magnet circuit and lock the signal arm in its safety position until
the controlling relay circuit is broken substantially as described and shown in Figs. 1
and 2 of the drawings.
3. In a signal controlling and operating apparatus; a cam mounted on a signal arm
spindle engaging with a stop arm actuated by the controlling relay magnet
substantially as described and for the purpose set forth.
4. A signalling controlling and operating apparatus in which the signal arm is
actuated by motor magnets controlled by a relay, the whole arranged constructed
and operating substantially as described with reference to Figs. 1 and 2 of the
drawings.
5. In a signal controlling and operating apparatus; motor magnets acting
differentially on armatures connected to the signal, in combination with a combined
locking armature and circuit breaking lever operated by a magnet in the main circuit
to break the motor magnet circuit and lock the signal arm in its safety position until
the controlling relay circuit is broken; substantially as described and shown in Fig. 3
of the drawings.
6. In a signal controlling and operating apparatus, a locking slide connected to the
signal arm engaging with a stop hook on the controlling relay armature so as to lock
the signal arm at danger substantially as described and shown in Fig. 3 of the
drawings:
7. A signal controlling and operating apparatus in which the signal arm is actuated
by motor magnets controlled by a relay the whole arranged constructed and operating
substantially as described with reference to Fig. 3 of the drawings.
Dated this. 19th day of June 1807.
WHEATLEY & MACKENZIE,.
40, Chancery Lane, London, W.C., Agents.