Electrical Apparatus for Signalling on Railways.
Year: 1893

page_text: Date of Application, 9th Oct., 1893
Complete Specification Left, 12th June, 1894-Accepted, 14th July, 1894
PROVISIONAL SPECIFICATION.
Electrical Apparatus for Signalling on Railways.
I, EDWARD TYER, of Ashwin Street, Dalston, in the County of London,
Electrical Engineer, do hereby declare the nature of this invention to be as
follows:-
In my Specification No. 1044 of 1879 I described electric signalling apparatus
specially adapted for use in signal cabins of railways for controlling traffic on the block
system. My present invention relates to improvements in the construction of such
an apparatus and to the use in combination with it of a safety switch and contact
arrangement. The apparatus is contained in a box or casing having projecting in
front of it a handle which can be turned partly round, thus turning a commutating
disc. Through the tubular axis of the handle passes a plunger which carries the
commutating disc. On turning the handle into the one or the other of the two positions,
and then pushing in the plunger, the commutating disc, being thus pressed against
springs arranged on the back of the box, makes certain contacts whereby signals
are transmitted, locked or released. So far the apparatus is of known construction,
and operates in the known manner, the act of turning the handle moving one or
other of a pair of screens presenting through a glass in front of the box words such
as "Train on line or "Line clear."
According to my present invention I provide three screens which may be marked
respectively "Train on line," "Line clear," and "Train out of section," one of
these is fixed behind the glass, and visible except when it is obstructed by either of
the other two coming in front of it. One of the two moveable screens is fixed to
the axis of the handle and moves with it, moving aside the third from behind the
glass. But the third screen thus moved aside, though overbalanced, is retained by
a pawl and cannot again present itself until the pawl is released by the movement
of the armature of an electromagnet excited by a current transmitted from another
station or in consequence of a contact being made by the passage of a train over
some part of the line. Another pawl, subject to the action of the same electro-
magnet, forms a stop to an arm on the axis of the commutator handle preventing
the handle from being turned in the one direction until the magnet is excited.
When this pawl is released and the handle is turned, another arm on the axis of
the handle, acting on a spring, breaks a contact in a signalling circuit, and thus
prevents the operator from giving certain signals until the commutator handle
is turned back. The effect of the arrangements above described is that the
operator can turn the commutator handle to one of its positions, say to the right,
and can give certain signals, but cannot turn his handle back to the left until the
action of the electro magnet releases the pawl which holds it, and then, when he
does turn the handle to the left, he can no longer give the before mentioned signals.
In this manner greater safety of traffic is ensured, than could be ensured by the
use of the block signalling apparatus unprovided with the pawls and contact spring
above described.
Dated this 9th day of October 1893.
ABEL & IMRAY,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Electrical Apparatus for Signalling on Railways.
I, EDWARD TYER, of Ashwin Street, Dalston, in the County of London,
Electrical 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 :-
In my Specification No. 1044 of 1870 I described electric signalling apparatus
specially adapted for use in signal cabins of railways for controlling traffic on the
block system. My present invention relates to improvements in the construction
of such an apparatus and to the use in combination with it of a safety switch and
contact arrangement.
Fig. 1 of the accompanying drawings is an elevation of the apparatus with the
door of its case opened back to shew the interior;
Fig. 2 is a plan.
The apparatus is contained in a box or casing A having projecting in front of it
a handle B which can be turned partly round, thus turning a commutating disc D.
Through the tubular axis of the handle B passes a plunger D' which carries the
commutating disc D. On turning the handle into the one or the other of the two
positions and then pushing in the plunger, the commutating disc, being thus pressed
against springs E arranged on the back of the box A makes certain contacts
whereby signals are transmitted, locked or released.
So far the apparatus is of known construction, and operates in the known manner,
the act of turning the handle moving one or other of a pair of screens presenting
Train on line or Line
through a glass in front of the box words such as
clear.'
"
According to my present invention I provide three screens which as indicated by
dotted lines in Fig. 1 may be marked respectively S¹ "Train on line," S " Line
is fixed
clear" and S "Train out of section," one of these "Train on line
behind the glass, and visible except when it is obstructed by either of the other two
coming in front of it.
One of the two moveable screens namely that indicating "Line clear" is fixed
to the axis of the handle B and moves with it, moving aside the third namely
"Train out of section" from behind the glass. But the third screen S' thus
moved aside, though overbalanced by counterweight is retained by a pawl P and
cannot again present itself until the pawl P is released by the movement of the
armature H of an electromagnet excited by a current transmitted from another
station or in consequence of a contact being made by the passage of a train over
some part of the line.
Another pawl K subject to the action of the same electromagnet, forms a stop
to an arm F on the axis of the commutator handle, preventing the handle from
being turned in the direction of the arrow until the magnet is excited. When this
pawl K is lifted and the handle is turned, another arm N on the axis of the handle
acting on a spring n breaks a contact in a signalling circuit, and thus prevents the
operator from giving certain signals until the commutator handle is turned back.
The safety switch is of the same construction as that described in my prior
Specification No. 12142 of 1893, and the parts are marked by the same reference
letters as in Figs. 3, 4 and 5 of the said Specification, the switch as arranged
according to my present invention being also provided as before with pawl M spring
lever Land contact spring / to operate as described in the previous Specification.
The effect of the arrangements above described is that the operator can turn the
commutator handle B to one of its positions, say to the right so as to expose the
screen S¹ giving the signal "Train on line "but cannot turn his handle back to
the left until the action of the electromagnet armature H releases the pawl K, and
then when he does turn the handle to the left, so as to shew screen S indicating

page_text: "Line clear" he can no longer give the before mentioned signals having cause.l
the arm N to lift the spring n in the signalling circuit, and he also by this motion
causes the arm F to push aside the lever L and move the spring 1 from contact C
to contact E thus opening his operating local circuit and though he can turn his
commutator handle back for signalling purposes he cannot close his operating local
circuit, until by the action of the electromagnet the pawl M is lifted allowing the
spring lever L to move back, this same action lifting the pawl P by acting on its
tail P and thus allowing the screen S³ indicating "Train out of section
present itself.
to
The signalling handle remains locked until by another action of the switch it
can be turned to the left exposing the screen $' indicating "Line clear” which
pushes aside the screen S³.
In this manner greater safety of traffic is ensured, than could be ensured by the
use of the block signalling apparatus unprovided with the pawls and contact
spring above described.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
In electrical apparatus for signalling on railways the combination with the
signalling handle and plunger of three screens and a safety switch arranged and
operating, substantially as and for the purposes set forth.
101
CT 1001
ABEL & IMRAY,
Agents for the Applicant.