IMPROVED METHOD OF AND APPARATUS FOR BLOCK SIGNALLING ON RAILWAYS
Year: 1885

page_text: I RICHARD ROBERT HARPER of 86 Clifton Street, Finsbury London Electrician,
do hereby declare the nature of my said invention for "IMPROVED METHOD OF
AND APPARATUS FOR BLOCK SIGNALLING ON RAILWAYS" to be as follows:-
The object of this invention is an improved method of and apparatus for block
signalling on railways whereby I obtain three signals on a one wire system by the
use of certain means of joining up the electrical connections.
For the purpose of my invention I provide an additional or third set of
commutator springs to single wire block signalling telegraph instruments which
springs are in connection with a set of resistance coils or shunt fitted in the interior
of the instrument from which coils the wire is carried to the coils of the electro
magnet, the amount of resistance being arranged or regulated so that the current
shall neutralise or overcome the residual magnetism in the electro magnets thus
liberating the armature and allowing the needle to fall to a vertical position by
gravity.
The three sets of commutator springs are operated by a single push or plunger
which when pushed in actuates a lever plate having a contact piece of insulated
material which in its turn presses against one of the three sets of commutator
springs.
.
The position of the lever plate with its contact piece is altered to correspond or
be opposite to one or other of the sets of commutator springs by being mounted
on a sliding plate provided with a rack which is actuated by cogs mounted on a
sinall disc whose axis or spindle is carried through to the front of the instrument
where it terminates in a milled head which is turned by the operator. The
spindle which carries the small disc and cogs, also carries a large disc having
three indices or indicators marked on it which may be the words "Line clear"
"Train on line" and "Train off but section blocked" only one of the indicators
being visible at one time.
When the large disc is turned to the position showing "Line clear" the lever plate
with its contact piece is opposite say the right hand set of commutator springs;
when the indicating disc is turned to "Train on line" the lever plate and contact

page_text: piece is moved with it to a position opposite say the centre set of commutator
springs; when the indicator is moved round to "Train off but section blocked"
the lever plate and contact piece has moved to a position opposite the additional or
third set of commutator springs which put the resistance coils or shunt into the
circuit thus causing the neutralization of the residual electro magnetism and
liberating the indicator needle on the dial plate of his own and of the distant
station thus allowing the needle or other index to assume a vertical position
indicat ng "Section blocked."
The call bell is operated on the same circuit as that on which the last signal
was sent.
In some cases it may be found more convenient to use a switch to operate the
resistance coils or shunt instead of the additional set of commutator springs
hereinbefore referred to.

page_text: Railways.
I RICHARD ROBERT HARPER of 86 Clifton Street, Finsbury, London, Electrician,
do hereby declare the nature of this invention and in what manner the same
is to be performned to be particularly described and ascertained in and by the
following statement:―
This invention consists of a new and improved single wire system of block
signalling for railways, the main feature of which is that three signals are obtained.
And in certain improvements in and arrangements of block signalling instruments
and circuits by means of which this invention may be carried out. The instrument
or set of instruments consists of the following parts, namely:-
Three sets of commutator springs, the set which is used in signalling that the
line or section is blocked being arranged to put into the circuit resistances or a
shunt for the purpose of driving out or neutralizing the residual magnetism of the
pole pieces of the electromagnets actuating the indices of the indicating instrument.
By means of a suitable mechanical arrangement the three sets of commutator
springs are operated by a single plunger, the set last operated being indicated by
words or marks upon a disc, the indication remaining visible and it being impossible
to send a different signal until the disc has been turned to indicate such different
signal by the signalman or operator.
An indicating instrument having two indices maintained in position by residual
magnetism or gravity, the one index to register incoming, and the other outgoing
signals.
A bell or gong to give bell signals and apparatus consisting of relay &c. for
striking the said bell or gong.
In the drawing annexed to this specification Figures 1 and 2 are elevations of
an instrument constructed according to this invention. The mechanism is enclosed
within cases A, A, A, of mahogany upon a mahogany back or board. B is a box
of resistance coils. C, C, are the coils of an ordinary electro magnet for sounding
the bell C. Its armature D is pivotted and carries the bell hammer rod E with
the hammer F at its extremity. G, G, are the coils of the relay in connection
with the line circuit for completing the local circuit. The armature H is fixed
upon a brass strip I which is pivotted at J and held off the electro-magnet
poles and against the dead point K by means of the adjustable spring J. Lis
the live point or contact of the relay by which the local circuit is completed
through the local or bell coils C, C.
Figure 3 is a part sectional elevation showing the bell appliances. Mand Mare
brass plates upon which the electro-magnets C, C, and G, G, are respectively fixed.
N is the spring of the armature D adjustable by means of the screws N¹.
The face P of the indicating instrument is seen through a glass in the front of
its casing. The face P consisting of a plate of zinc is preferably marked with
words as shown at Figure 1. It is colored green with a red horizontal line
dividing the up and down line indices the circular patch bearing the words " Line

page_text: Clear" being white and the others red on both dials. The hands or indices Q, Q',
are blackened. a, a, b, b¹, are steel permanent magnets with like poles adjacent as
shown. They are screwed to the brass plates R, S, T and U are known as
magnetically induced needle axles carrying the indices Q, Q, V and W are coils
of electro-magnets. Figure 4 is a drawing of one of these electro-magnets to a.
larger scale. It consists of two cores X, Y, of soft iron (upon which are the
coils V, V,) coupled by a plate Z and having steel or iron pole pieces d, d', to
which are attached hornplates c, c, and c², c³, "The axle and needle T¹ is arranged
between the said hornplates as seen at Figure 2.
Figure 5 represents the commutator springs and arrangements for working
them. c, e¹, e, are brass key plates and below each arc three springs f, g, h,
f, g, h, and f, g, h. The key plates have at their extremities, plates m, m', m²,
of ivory, vulcanite or other insulating material for the nose n of the hinged or
lever plate p to strike or press against when the plunger is depressed. q (Figure 2)
is a milled head or handle for turning the disc carrying the indicator plates,,,
in order to bring said plates to the glazed opening r² in the case of the instrument.
The disc has upon one surface recesses for the reception of a detent s on spring t
to act as a stop and hold the indicator plates in the proper position. The position
of the hinged or lever plate p can be altered to correspond or be opposite to one or
other of the sets of commutator springs said lever plate being hinged on a sliding
.plate w moving in guides a¹² and provided with a rack which is actuated by
cogs von the face of a small disc u fixed on the axis or spindle of the milled head
or handle q. is the plunger the spindle of which passes through a slot in the
sliding plate w of the shape shown at Figure 6, the said spindle being so formed
that the plunger can only be depressed when the spindle is in the openings of the
slot marked ³, 3, ³, Figure 6, the spindle is continued through a slot in the lever
plate and terminates with the milled head y. A¹ is a yoke or current reversing
switch which is actuated by one of the projections CC striking against one of
the projections B' B' on the yoke A¹ (Figure 5).
The arrangement of circuits is represented by the diagram on sheet 2 of the
drawings, the operation of the system being as follows:-
"
If the signal
Line Clear" is to be sent from station A to station B, the milled
head or handle of the instrument (see Sheet 1) is turned until the indication "Line
Clear" stops at the opening in the instrument case. The plunger is then pressed
and moves the yoke C (Sheet 2) upon its centre or pivot D, at the same time
operating the commutator springs b, b, A current from say the zinc pole of the
battery now passes to earth through the coils of the electro-magnet of the lower
At the same time
index at station A causing the needle to indicate "Line Clear."
the copper current passes out to line through the coils of the electro-magnet of the
upper index at station B in a similar manner indicating "Line Clear" thence through
the relay (completing the local circuit at station B and sounding the bell) to earth.
When it is desired to send the signal "Train on Line" the circuit is completed
in a similar manner but by means of the set a of commutator springs. The
plunger by pressing the yoke at the end opposite to that pressed in signalling
"Line Clear" places said yoke in a position which will reverse the direction of the
current for sending the line blocked signal.
When the signal "Line Blocked" is to be sent the set c of commutator springs
is operated by the plunger, but the yoke remaining in the position in which it was
placed in sending the last signal the resistance g is included in the circuit the
residual magnetism in the electro-magnets neutralized and their indices fall to
indicate "Line Blocked" in which position they are maintained by gravity and the
permanent magnet pins above the needle at T² U² (Sheet 1).
By pressing the plunger to give bell signals the current sent is flowing in the
same direction as that used in sending the last signal, and thus the call bell can be
operated at any time.
If desirable the additional set of commutator springs may be dispensed with
and a switch employed. The switch would be so arranged as to put the resistance

page_text: "
coils or shunt in circuit whether the last signal sent was 'Line Clear" or train
on line.
The switch key or shunting device (which may be separate from the instrument
or take the place of the additional set of commutator springs) may be connected
in any convenient manner in the electric circuit either at the sending or receiving
station for the purpose of producing the before mentioned additional or "Line
Blocked" signal.
On sheet 3 of the annexed drawings Diagram 1 shows the arrangement of a
portion of the circuit with the battery f joined to the shunt direct. In this case
the brass key plate c has in addition to the contact piece h (attached thereto but
insulated therefrom and in connection with the commutator springs c¹, c², c³,) a
second contact piece j also insulated from the said key plate and capable of
connecting contacts and l. The resistance g or shunt would represent in this
arrangement about 2 ohms.
Diagram 2 shows the arrangement of a portion of the circuit with divided
battery when low resistance is used. The yoke C is represented so turned upon
its centre D.as to connect the commutator springs cl and c² with the poles C and Z
respectively of one cell of the battery f, the poles of the battery being connected
with the commutator springs a¹ and b³ respectively. Instead of connecting one
cell of the battery with the yoke C as above described and shown in the drawings,
a distinct battery may be employed for the purpose if desired. The arrangement
of the rest of the circuit will be understood by reference to Sheet 2 of the annexed
drawings and the description thereof.
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
First. The mode of signalling and arrangement of circuits and apparatus
constituting a single wire system of block signalling telegraphy for obtaining three
signals in the manner hereinbefore set forth.
Secondly. The application to a block signalling instrument in general construc-
tion similar to that described in this specification of an additional or third set of
commutator springs or its equivalent with resistances or shunt for the purpose of
adapting such instrument to the system of block signalling claimed as part of this
invention.
Thirdly. In a block signalling instrument for sending three signals, the particular
combination of parts constituting the residually polarized magnetic indicating
instrument herein described.
Fourthly. The combination of plunger, leverplate, slide plate, with rack and
guides and handle, disc with indications and pinion or disc with cogs for the
purpose of operating several sets of commutator springs substantially as described
and shown in the annexed drawings.
Fifthly. The method as described of obtaining a "line blocked" electric signal
by shunting the current or inserting resistances in the circuit for the purpose of
depolarizing the electro magnets in a residually polarized magnetic systein.
H. GARDNER,
166, Fleet Street, London,
Agent for the said R. R. Harper.
Dated this 16th day of October 1885.
H. GARDNER,
166, Fleet Street, London,
Agent for the said R. R. Harper.