Improvements in Railway Signalling Apparatus.
Year: 1894

page_text: Date of Application, 15th May, 1894
Complete Specification Left, 15th Oct., 1894-Accepted, 17th Nov.,
1894
PROVISIONAL SPECIFICATION.
Improvements in Railway Signalling Apparatus.
I, CHARLES LAVINGTON FIELDER, of Rosendale, Gibbon Road, Kingston-on-
Thames, Surrey, Engineer's Draughtsman do hereby declare the nature of this
invention to be as follows:-
This invention has reference to improvements in the mode of automatically
actuating railway signal rods by a combination of mechanical and electrical parts.
The uses for which my actuator is intended and its mode of operation are more
particularly as follows:-
It is desirable, especially in the case of starting signals, that a train, immediately
on passing its permissive signal, should itself replace that signal to the danger
position independently of the signalman putting back the signal lever in his cabin.
It is also often desirable that the lowering of signals, this again more especially
in the case of starting signals, should be rendered impossible without the permission,
usually given electrically, of the signalman in the cabin controlling the next section
of road; and that such permission should be capable of withdrawal or suspension
whether the first signalman has made use of it by lowering his signal or not,
provided always that such permission or its effective result shall not have been
already nullified by a passing train as hereinbefore referred to.
A further instance of its application is where two or more rods are required to
work interdependently, the particular signal or signals to be lowered being controlled
by the electric current or currents through one or more actuators.
My invention is also applicable to many other purposes where a rod, bar, blade
or other article is required to be alternatively rigid or collapsible in its length, the
controlling agent being electricity.
The mode of operation is thus :-
In a metallic case permanently fixed, in the case of signals, to the signal post, in
any position in the length of the operating rod, a normally flexible joint or actual
severance in said rod is introduced.
In this case a linked joint, composed of one or more links of equal or unequal
length, is adopted, the extremities of the linked portion being attached by ordinary
pin joints to the upper and lower lengths of the down rod respectively, which said
lengths of down rod immediately beyond their junction with the said links pass
through sleeves in the enclosing case, these sleeves forming guides to the upward and
downward motion of the two lengths of rod and of their connecting links.
The said links may be united by a pin which carries a roller or pulley, the pin
The links
and its roller being centred out of the line of thrust in the down rod.
are guided on their back edge and throughout their length by a rib called the back
guide permanently fixed to or forming part of the enclosing case, and they may
or may not travel on this back guide on rollers attached to them or to the rib itself.
The pulley or roller carried by the links at their juncture extends slightly beyond
that edge of the links opposite to the back guide.
In the normal positiou a hinged or pivotted locking blade is suspended and rests
by its own gravity against the said pulley.
When the lower portion of the signal rod is raised by the pulling of the signal
lever the link motion, owing to its pulley at the pin joint being outside the line of
thrust, presses outwards by means of this pulley against the suspended locking
blade and meeting no retaining pressure lifts the said locking blade and by its

page_text: own collapsing action prevents that part of the signal rod below the actuator from
communicating its upward movement to the portion above the actuator and
consequently renders the signalman powerless to operate the signal arm.
An electro magnet is fixed within the case in such a way that its armature lever
when actuated by the current interposes a distance piece of any convenient shape,
preferably armed with small rollers or cams at its rubbing points, between the
locking blade and a fixed guide block, or the armature lever may itself form the
distance piece also similarly provided by preference with a roller or rollers to meet
the contact of the said suspended locking blade, the pressure of the blade being
in that case carried immediately through the armature lever to its supporting pin
or hinge; or the armature lever may merely carry an arm or actuate a crank or
be otherwise fitted with rollers to be interposed between the locking blade and a
stop block on the energizing of the magnet.
Another way of applying the armature lever to the locking blade is by arranging
one or more rollers or cams upon it in such a way that when actuated it would
take hold of and restrain the blade from moving on its pin or hinge. It is
obvious that the character of the magnet or its position is not material to the
securing of the locking blade in any such manner hereinbefore described.
The energizing of the magnet, by which such interposition of a distance piece or
restraining or locking pulley in connection with the armature lever is attained,
may be by the permissive closing of the circuit by the advance signalman at once,
in which case the locking blade is immediately locked and the signal can be lowered
by the mere mechanical movement of the lever, or it may he performed by the
advance signalman at first partially closing the circuit through an armature in his
instrument, the final completion of the circuit occurring when the first signalman in
pulling his lever actuates a contact.
In whatever way the circuit is closed the functions of the actuator are the
same.
The magnet operating the armature lever and its parts in the manner herein-
before described secures the suspended locking blade in its normal position and on
the lever being pulled the links in the down rod are restrained from buckling or
collapsing and the whole signal rod with its linked joint from the ground lever
to the signal arm becomes rigid and ascends guided by the sleeves in the actuator.
case until the arm is lowered.
The signal arm remains thus lowered until released to the danger position by one
of several occurrences.
First, mechanically, by the signalman reversing his lever, when the whole rod
moves down rigidly; this mechanical lowering of the signal rod also incidentally
on the completion of the lever's backward movement breaks the circuit and releases
the locking blade, but of course this alternate lowering and raising of the signal
arm, provided the sanctioning act of the advance signalman remains in force, can
he repeated indefinitely..
Secondly, electrically, by the cancelling or suspending of the sanction by the
advance signalman in reversing the operation by which he either completed the
circuit himself or enabled the first signalman to do so.
Thirdly, also electrically, by the passage of a train breaking a contact and
permanently destroying the circuit by releasing the aforesaid armature in the
advance signalman's instrument.
Fourthly, by any accidental failure of the current or of the wires.
In the three last instances, where the lowering of the signal rod is due to a
severance of the circuit, the armature with its lever and connections drops by
gravity and the distance piece that previously secured the locking blade is disengaged.
The downward pressure of the signal rod acting outwardly through the link
roller in the manner already described forces the released locking blade to revolve
on its hinge or pivot, and the linked portion assumes a partially folded or collapsed
condition as the signal arm returns to its danger position although the signalman
shall not have replaced his lever.

page_text: When in operation the outward pressure of the link pulley against the locking
blade is dependent on the greater or lesser distance the said pulley is fixed outside
the centre of thrust in the signal rod, and the resultant pressure of the blade against
the distance piece or other attachment to the armature lever is dependent upon the
relative distances apart of the locking blade's pivot, the link roller and the distance
piece that locks the blade.
By the combination of the distance piece, the link pulley and the locking blade in
the manner adopted the resultant pressure upon the said distance piece remains at
its maximum amount momentarily only, viz., at the initial moment of travel of the
link pulley in ascending, and it gradually lessens as the said link pulley reaches its
greatest limit of upward travel, at which point the pressure of the locking blade
on the distance piece almost disappears and ensures the instant disengagement of
the distance piece on the severance of the current.
A further advantage can be secured by the peculiar alternative form of locking
blade proposed, in respect to economy of space and consequent reduction in the
size of the actuator case and the greater facility with which the magnet and its
operating connections can be brought to bear upon the said blade; but the exact
shape and mode of suspending the said locking blade is not material to the principle
of operation herein devised.
Dated this 12th day of May 1894.
CHARLES LAVINGTON FIELDER.
COMPLETE SPECIFICATION.
Improvements in Railway Signalling Apparatus.
I CHARLES LAVINGTON FIELDER of Rosendale, Gibbon Road, Kingston-on-
Thames, in the County of Surrey, England, Engineer's Draughtsman 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:—
This invention has reference to improvements in the mode of automatically
actuating railway signal rods by a combination of electrical and mechanical parts.
The uses for which my actuator is intended are more particularly as follows:-
In railway signalling it is often desirable, especially in the case of starting
signals, that a train immediately on or soon after passing its permissive signal
should itself place that signal to the danger position, independently of the signalman
putting back the signal lever in his cabin.
It is often also desirable that the lowering of such signals should be rendered
impossible without the permission, usually given electrically, of the signalman in
charge of the next section of road, and, collaterally, that such electrical permission
when established by the signalman in advance should be capable of withdrawal by
him whether the first signalman has lowered the signal or not, and that such act
of withdrawal should replace the signal to the danger position if it has previously
been lowered, provided always that the passage of a train past the signal so
lowered shall not have rendered such withdrawal ineffectual.
A further case of its application is where two or more signal rods are required
to work interdependently, the particular sigual or signals to be lowered or their
sequence of movement being controlled by the electric current or currents acting
through one or more actuators.
The usual way of achieving the results above mentioned is by various forms of
divided rods attached to the signal post in such a way that normally an absolute
break in the signal rod exists, but which break is capable of being closed by the
movement of parts having for their motive force electricity, the entire mechanism
in some devices moving with the rod when operated in the permissive condition

page_text: and aming by gravity with more of its Concussion on
place.
In my device the rod preserves its connection and continuity throughout, whether
in the normal or the operating condition, and the aforesaid mechanism is permanently
established on the post, the rod alone travelling when the act of lowering the signal
takes place.
My invention I will proceed to describe as follows:-
In a metallic case, .fs'
a," permanently fixed to the signal post at any position in
the length of the operating rod, a normally flexible joint, b', 6, 6, in the form
of a linked connection between the upper, e, and the lower, d, portions of the
signal rod, is introduced; the links may be two or more and may likewise be of
equal or unequal length.
The said linked portion, 61, 62, 63, at its extremities is attached by ordinary pin
joints to the contiguous ends, e and d, of the aforesaid signal rod, and these ends,
immediately beyond their junction with the linked portion pass through sleeves
or guides, e, e, in the enclosing case, a, and so direct the true upward and downward
motion of themselves, either individually when the linked portion, b¹, 62, 63, is free
to collapse, or in unison when the said linked portion is held rigid.
The links themselves, in the case of two only being employed (although it is
obvious that an identical principle and action can be observed by increasing the
mere number of links) are united by a pin joint at 6, the said pin in addition
carrying a friction roller or pulley, f, this pin and its roller being centred out of
the true line of thrust in the down rod for the purpose hereinafter described.
The link portion, 6, 12, 63, being preferably constructed of flat metallic links,
and its central connecting piu at, 62, being on one side of the true line of thrust
in the down rod, can by its own nature buckle or collapse in one direction only,
viz. to the right or to the left in accordance whether the said connecting pin is
to the right or to the left of the said true line of thrust.
For the purpose of relieving the portions, c and d, of the down rod from the
strain which would otherwise be brought upon them by the resistance of the
locking blade, j, (during the period of the upward travel of the linked portion)
re-acting through the links, a rib or surface, g, g, is permanently fixed to or forms
part of the enclosing case, a. When the link portion is held rigid and operated
in the manner hereinafter appearing, its two ends travel on this bearing surface, 9, 9,
by means of subsidiary rollers or pulleys, h, h, attached separately to the several
links, though these subsidiary rollers, h, h, are not essential and are introduced
merely to facilitate the travel of the link portion along its fixed path, g.
The pulley,, before referred to, extends beyond that edge of the links opposite
to the fixed path, g.
In the normal position a hinged or pivotted locking blade, j, is suspended and
rests vertically by its own gravity against the said pulley, f, but is free to be
removed from its vertical position by the natural outward pressure of pulley, f
(owing to the said pulley, f, being centred out of the true line of thrust in the
signal rod), when the lower portion, d, of the said signal rod is raised by the
pulling of the signal lever in the cabin. The locking blade, j, thus, normally,
offering no restraining pressure, the link portion, 6, 6, 63, is free to collapse and
by its collapsing action, as shown in dotted lines in Figure 1 of the drawing,
prevents the portion, d, of the signal rod below the actuator from communicating
its motion to the portion, e, above the actuator, and, consequently renders the
signalman powerless to operate the signal arm.
The locking blade, j, is of such a shape and is so centred that it passes to its
hinge, p, either through the upper portion of the link motion, in which case
that portion of the link motion to receive it is made in two parts, or otherwise
it may pass in front of or behind the link motion, the result being in either
case, that a greater degree of gravity is given to the said locking blade to assure
its descent to close contact with pulley, additional advantages of such an
arrangement being that the reduced natural throw for swing of the said locking.

page_text: blade in the outward or horizontal direction increases the facility with which the
magnet and its operating parts hereinafter referred to can be brought to bear
upon the said locking blade, j, and that the actuating case can be reduced to
more economical dimensions.
An electro magnet, k, is fixed within the case, a, in such a way that its armature
lever, I, when actuated by the current, interposes a distance piece, m, preferably.
terminating in small rollers or pulleys, n, n, n, between the suspended blade, 1, and
a fixed guide block, g, or the armature lever may itself form the distance piece,
also similarly provided if desirable with a small friction roller or rollers, coming
in contact with the blade, j, the pressure of the blade, j, being in the latter case
carried immediately through the armature lever to its supporting pin or hinge, o.
Another way of applying the armature lever to the locking blade, i, is by
arranging a roller upon it in such a way that when actuated by the current it will
take hold of and restrain the blade from moving on its hinge when the link
motion, by its tendency to collapse on the signal lever being used, presses upon it
through the pulley, f.
It is obvious that the character and position of the electro magnet and the
precise details of its operating parts are not essential to the principle of action
here applied.
The circuit, by which such interposition of a distance piece or restraining pulley
in connection with the armature lever is attained, is made and broken by various
arrangements of electrical connections and instruments as now used for similar
purposes, which arrangements are well known to and already in use by signal
engineers, and, as they are outside the limits of this invention, need not be referred
to in detail. It will be sufficient to say that :-
Normally, the armature lever, 1, being disengaged, see Figure 1, the distance
piece, m, rests by gravity out of the line of motion of the locking blade, j, so
that the signalman in pulling his lever merely causes the link portion, 61, 62, 63, to
collapse, as shown by dotted lines in Figure 1, and bears the said locking blade
outwards, the upper portion, c, of the signal rod, and hence the signal arm itself,
remaining stationary.
On the necessary electrical permission being given and the circuit closed, by
whatever arrangements these are carried out the action of the actuator is the
same :-
The electro magnet, k, operating the armature lever, l, and its parts, m, n, in.
the manner before described, locks the suspended guide or locking blade, j, in the
vertical position and, on the lever being pulled, the links, 61, 62, 68, in the down rod
are restrained from collapsing and the whole signal rod with its linked joint from.
the balance lever to the signal arm becomes rigid and ascends, guided by the sleeves
in the actuator case, until the arm is lowered and the links occupy the position.
shown by full lines in Figure 2.
The signal arm remains thus lowered until released to the danger position by
One of several occurrences: first, mechanically, by the first signalman reversing
his lever in the cabin, when the whole rod moves down and the signal arm is con-
sequently replaced; this mechanical lowering and raising of the signal, provided
the sanctioning act of the advance signalman remains in force, can of course be.
repeated indefinitely; secondly, electrically, by the withdrawal of the sanction by
the advance signalman; and thirdly, also electrically, by a train in passing
breaking a contact in connection with the actuator; fourthly, by any accidental
failure of the wires or of the current.
In the three latter instances, where the movement of the arm to the danger
position is due to the breaking or short circuiting of the electric current, the
armature lever, l, drops by gravity, and the distance piece, m, also by its own
gravity, disengages from the locking blade, j, the downward pressure of the
portion, c, of the signal rod acting outwardly through the link roller, f, in the
manner already described, forces the released blade, j, to turn on its pivot, p,
whereby the link portion, b', 62, 63, assumes (as shown in Figure 2 by dotted lines).

page_text: a collapsed position as the signal arm returns to. its normal danger position.
although the signalman shall not yet have replaced his lever to the normal
position.
The outward pressure of the link pulley, f, against the locking blade, j, is
dependent (in accordance with well known inechanical principles) on the greater
or lesser distance the said pulley, f, is fixed outside the centre line of thrust in the
signal rod; and the resultant pressure of the blade, j, against the distance or
locking piece, m, actuated by the armature lever, I, is similarly dependent upon
the relative distances apart of the locking blade's pivot, p, the link pulley, f, and
the said distance piece, 'm.
By the arrangement of the link pulley, t, the locking blade, j, and the distance
piece, m, in the manner shown, the resultant pressure on the distance piece, m,
remains at its maximum amount momentarily only, viz. at the initial moment of
travel of the link pulley, f, in ascending; and it gradually lessens as the said link
pulley,, approaches its greater limit of upward travel, at which point the pressure
of the locking blade j, upon the distance piece, m, almost disappears, and ensures
the instant disengagement of the distance piece, m, by reason of its own gravity,
on the severance of the electric circuit.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In railway signal replacing mechanism, a link portion interposed in the signal
rod between the balance lever and the arm, the said link portion having one joint
non-axial with the said rod, and being only held rigid when the electric circuit is
made (thereby allowing the movement of the signal arm to the "a'l right" position
when the lever working the signal is operated), the link motion collapsing if the
said lever is pulled before the electric circuit is made, thereby preventing the
signal arm from being deflected, and, ou the circuit being completed and the lever
worked, automatically replacing the signal to the danger position by means of
the collapsing of the said link portion whenever the circuit is again broken, all
substantially as and for the purposes described and illustrated.
2. The combination of a link motion having one non-axial joint, with a friction
roller travelling (in the operative condition) on a locking or restraining blade
substantially as and for the purposes set forth herein and illustrated in the
drawing.
3. A locking blade so hinged that its stable point is removed within or beyond'
the line of motion in the signal rod, thus obtaining increased force of gravity in
the said blade and also restricting its throw or swing in one horizontal direction
when free of its retaining mechanism, all substantially as and for the purposes set
forth and illustrated.
4. The combination of a distance piece provided with friction rollers, and au
armature lever, the said distance piece being pivotted to and moving with the said
armature lever, as and for the special purpose herein set forth and illustrated.
5. The combination of an armature lever, a distance piece pivotted thereto and
armed with friction roller, and a fixed guide block directing the said distance
piece to its work substantially as herein set forth.
6. The combination of a link motion, a friction pulley attached thereto, a locking
blade on which the said pulley operatively travels, a distance piece restraining
the said blade when actuated by an electro magnet through an armature lever,
and a fixed guide block directing the movement of the said distance piece,
substantially as and for the purposes set forth and illustrated.
Dated this 13th day of October 1894. :
CHARLES LAVINGTON FIELDER.