AN IMPROVEMENT IN APPARATUS FOR ELECTRICALLY CONTROLLING RAILWAY SIGNALS
Year: 1884

page_text: I, CHARLES HODGSON of Canterbury Road Kilburn in the County of Middlesex,
Mechanical Engineer, do hereby declare the nature of my Invention for "AN
IMPROVEMENT IN APPARATUS FOR ELECTRICALLY CONTROLLING RAILWAY SIGNALS"
to be as follows:-
It often happens that a railway signal should not be permitted to be displayed
so as to invite a train at one part of the line, unless the conditions at other parts of
the line are such as to allow the train to proceed with safety. It is therefore
necessary in such cases, to provide means of controlling the signal at one place by
electricity transmitted from other places. My Invention relates to means of effecting
such electrical control as I will describe, referring to the accompanying Drawing,
which illustrates one form of the apparatus that I employ as applied to an ordinary
semaphore sigual. A A¹ is the ordinary weighted lever which is worked by the
pull B. One arm A is linked by a rod C to the one D of two arms D and E that
are pivotted on the rod F, which is guided at G, and extends up the post to the
crank of the semaphore. The arms D and E are butt jointed, so that either can
move freely to a certain extent, round their common pivot, except when the butts
are in contact, in which case, when either is moved upwards, both move as a single
lever round the pin of the other. The arm E is linked by a slotted rod H to a pin
on the arm A¹. The arm E is also linked by a rod I to a lever J which has, at its
upper end a weight K and a spring armature L projecting therefrom. M is an
electromagnet, the coil of which is in an electrical circuit with the place where the
control of the signal is to be exercised. At this place, there is a contact arrangement,
that can be broken either directly by hand, or by a signal or other lever, or by the
action of telegraph signalling apparatus, or by the passage of a train over a treadle
or trigger on the line, this breaking of contact opening the circuit and rendering
the magnet M inert. When the weight K is in its elevated position, as shewn in
the Drawing, if the magnet M be then excited, its attraction on the armature L
holds the weight in that position, and, the rod I being then vertical or nearly so,
the arm E is held firmly up by it. If then, by pulling B, the lever arm A is raised,
raising D, until it butts against E, the farther ascent of A raises the common pivot
of D and E and thus raises the rod F, so as to lower the semaphore arm to indicate
"safety." If, while the arm A is thus raised, the current which excites M should
cease by breach of contact made elsewhere, the armature L is no longer attracted,
and the weight K descends to the position K¹, thus lowering E and permitting the

page_text: "E
rod F to descend and to raise the semaphore to the "danger" attitude, notwit-
standing that the arm A remains still up. When, by releasing the pull B, the
arm A is allowed to descend, raising the opposite arm A¹, the rod H is also raised,
causing the weight K again to ascend towards the magnet M. If the magnet
remains inert, the raising of A, by the pull of B has no effect in lowering the
*semaphore, because, by the slot of the rod H, K is permitted to descend and, as E
also descends, D, in ascending, merely moves round the common pivot of D and E,
without raising the rod F. Thus, when the semaphore arm has been lowered to
safety" by the local action of the pull B, it is raised to "danger" by the breach
of electrical contact elsewhere, rendering the magnet M inert, and so allowing K to
descend and lower E. And again, when the semaphore is at "danger," it cannot be
lowered to " safety by the local action of the pull B, unless the circuit of the
magnet M is closed, and the magnet is excited so as to retain K. in its raised
position, keeping E up. Although I have shewn in the Drawing a form of
apparatus, according to my Invention, that can be readily applied on an ordinary
semaphore signal post in conjunction with the pull, lever and rod usually employed
for working the signal, the details of the apparatus might obviously be modified so
suit other positions and conditions, the object, in all cases, being to prevent a signal
from being moved to or kept in the "safety attitude, by the action of the local
pull, unless also an electrical current, maintained by a contact elsewhere, renders
the pull effective for lowering the signal.
"
ABEL & IMRAY,
Agents for the Applicant,
28, Southampton Buildings,
London, W.C.

page_text: I, CHARLES HODGSON of Canterbury Road Kilburn in the County of Middlesex,
Mechanical Engineer do. hereby declare the nature of my said Invention for
"AN IMPROVEMENT IN APPARATUS FOR ELECTRICALLY CONTROLLING RAILWAY
SIGNALS" and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement, that is to say :-
It often happens that a railway signal should be under the control, not only of
the operator near it, but also of operators at a distance, and of trains passing along
the line. For example, the semaphore should not be capable of being lowered to
invite a train to enter a section of the line unless the operator at the distant end
of the section concurs with the operator at or near the signal in indicating safety.
And again a train having once entered a section should forbid other trains from
following it until it has attained a safe distance in advance. My Invention relates
to apparatus, which may be fixed on the signal post, whereby the working of the
signal under multiple control is effected as I will describe referring to the
accompanying Drawings. Fig. 1 shews the apparatus in the condition such that
the signal can be lowered to its "safety" attitude, Fig. 2 shows the signal lowered,
and Fig. 3 shews the signal retained in its "danger" attitude notwithstanding
that the lever for lowering it is worked.
6
A is the ordinary wire or cord by which the operator in the signal cabin acts to
pull down the signal which is counterweighted so that it will of itself take the
danger" attitude. The pull A. is attached to a loaded lever B from which a rod C
extends up to one arm D¹ of a sway beam pivotted at D on the guided signal rod E
The other arm D' is linked by a rod F to a heavy lever G which has at its upper
end, attached to it by a spring, an armature g. This armature, when the lever G
is raised, bears against the poles of an electro-magnet H, and if this magnet be
excited by a current of electricity, the attraction suffices to keep the lever G up?
As the rod F, when D³ is raised, is almost vertically over the pivot of G, there is
scarcely any strain tending to push G down except its own weight. An arm J on
the same pivot with G is linked by a slotted rod R to the lever B. The operation
of the apparatus so far described is as follows:-
The lever B, in taking the attitude shewn in Fig. 1, lowers D' and by means
of the rods F and R raises G, the signal rod E being down and the semaphore
standing at "danger."
If now the signalman desires to lower the signal, and if the signalman at a
distant station concurs with him by transmitting an electric current which, either
by itself, or by means of a relay closing the circuit of a local battery, excites the
electro-magnet H, then, G being held up by the attraction of H on g, and D' being
thus beld up, the pulling down of A moving the lever B as shewn in Fig. 2
causes D¹ to be raised, thus raising the rod E and causing the signal to be lowered.
If there be no electric current exciting H, then the lever G falls away as shewn
in Fig. 3, allowing D³ to descend, and in that case the raising of D' by the
movement of the lever B has no effect in raising the rod E and lowering the
signal.
In order to ensure the separation of the armature g from the magnet H when
the electrical current ceases, I place at K a permanent magnet having on it coils
connected to the coils of H and so wound that, when H is excited attracting g,
the permanent magnetism of K is neutralised, but when the current in the coils
of Hand K ceases, the permanent magnetisin of K, being no longer neutralised,
attracts an armature lever le which pressing against g pushes it away from contact
with the poles of H.

page_text: It is generally of advantage to derive the electrical current for H and K from a
local battery the circuit of which is closed by a current transmitted by a distant
operator to act on a contact key. When the signal has to be controlled by several
operators, the local circuit is arranged with several such contact keys, so that,
unless contact is made by all of them, the local circuit is not closed, and
consequently the lever G is not held up and the signal cannot be lowered. One of
these contacts may be commanded by a trigger or treadle situated at some place
on the railway line, so that it is acted on by a passing train; and thus the signal
can be prevented from being lowered until the train has passed the place where the
contact treadle or trigger is situated.
Although I have shewn and described H as an electro-magnet of ordinary kind
attracting g when it is excited by a current passing through its coils, it may in
some cases be a magnet of the kind K, that is to say a permanent magnet coiled
in such a manner that when a current passes its attractive force is neutralised.
When such a magnet is used, G will be held up and the signal will be capable of
being lowered only when no current passes; but, when a current passes, neutralising
the permanent magnetism, G will not be held up, and the pull will be ineffective in
lowering the signal.
Again it is often desirable, that the signal, having once been lowered to admit a
train to a section of the line, should not be capable of being lowered a second time
until the train has attained a certain distance or has entirely passed the section. In
order to provide for this, I place at L an electro-magnet having an armature lever
with wires at which, when the armature is not attracted; dip into cups of mercury
and close the circuit for H and K, but which, when the armature is attracted by L,
are raised out of the mercury, as shewn in Fig. 4, and thus prevent the circuit
for H and K from being closed. The armature of L is moved in the following
manner: On the signal rod E is mounted a counterweighted pawl 6 which, when Ĕ
is raised, passes freely the short arm of a lever M, but when E descends, e acting
on M moves upwards a rod m and this raises the armature of L to the position shewn
in Fig. 4, the wires being thus withdrawn from the mercury cups. If it happens
that the signalman at a distant station maintains an electrical current, indicating on
a block telegraph instrument that the line is clear and keeping closed the circuit
of the local battery, the current, either that from a distance or the local current
passing through the coils of L excites it, and as long as it remains excited, its
armature is held up by attraction. In this condition, as the wires are not
immersed, no current from the local battery can pass to H, and consequently the
lever G cannot be held up and the signal cannot be lowered. When, however, the
current exciting L ceases, the armature drops and the wires close their part of
the circuit for H, so that the apparatus is again in condition for lowering the signal
if all the operators connected with it concur.
Although I have described the parts, marked e, M, m, L and Z and their operation
in conjunction with the rest of the signal apparatus, it is to be understood that
I here make no claim to these parts, as they form the subject of a previous
application for Patent made by me on the 17th January 1884 N° 1633.
The apparatus which I have described is fixed on the signal post. Sometimes
however, it is convenient to fix it near the operating lever or in other situations.
Figs. 5, 6 and 7 shew the principal parts of the like apparatus applied in the
signal cabin, close to and worked by the ordinary signal lever B. This lever has
two arms one connected to D¹ and the other connected by the rod R to the arm J.
The pivot D of the sway beam is on the rod E connected to the signal pull A: The
arm D is connected by the link F to the heavy lever G which has its spring
armature g to face the poles of the electro-magnet H. The operation of these
parts is the same as that described with reference to Figs. 1, 2 and 3, that is
to say on pulling over the lever B from left to right, the rod E is raised lowering
the signal, if G is held up by the attraction of H, as shown in Fig. 6; but, if G
be not held up, the pulling over of B merely cants the lever D¹ D³, without
raising E and lowering the signal, as shewn in Fig. 7. It is to be understood that

page_text: the other details shewn in Figs. 1, 2, 3 and 4 may be added to the apparatus
shewn by Figs. 5, 6 and 7.
Having thus described the nature of my Invention and in what manner the same
is to be performed, I claim :-
-
1. Interposing between a railway signal and its motor a sway beam or its
equivalent, one end of which is worked by the motor, the middle of which is
connected to the signal, and the other end of which is either held stationary or is
left free as determined by an electro-magnet excited by a current transmitted or
brought into action from a distance, substantially as and for the purposes herein
set forth.
2. The combination of the lever B, the sway beam D¹ D' and signal rod E, with
the heavy lever G and magnet Ḥ and their connections, substantially as herein
described.