A Safety Switch for Electrical Lock and Block Apparatus on Railways.
Year: 1893

page_text: Date of Application, 20th June, 1893
Complete Specification Left, 16th Mar., 1894-Accepted, 21st Apr., 1894
PROVISIONAL SPECIFICATION.
A Safety Switch for Electrical Lock and Block Apparatus
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:-
My invention relates to a safety switch arranged in any conducting line for
electrically operating lock and block apparatus in such a manner that, when an
operator gives or unlocks a signal or moves or unlocks a set of points or performs
any other operation which leads to the blocking of part of a line by the admission
to it of a train or of a truck or carriage, he at the same time breaks a contact and
thereby renders farther electric operations impossible until the train or the trucks
or carriages have passed a treadle or other appliance on the line, by the action
of which an electric current is made to operate the safety switch so as to restore
the contact.
The safety switch is of the following description. A lever, pressed in one
direction by a spring, normally makes a contact by which the operator's local
circuit is closed, but when, by moving a push or plunger or a pull or lever, he
transmits a current to perform any of the signalling or other operations above
referred to, he at the same time moves this lever so as to break the contact for his
operating local circuit and make a contact for the circuit of the treadle or other
appliance on the line, and the lever thus moved is held in this position by a catch,
keeping the operating local circuit open. But, when the train or vehicle passes the
treadle or other appliance on the line, a current is transmitted to the coil of an
electro-magnet in the safety switch, and its armature is attracted, releasing the
catch and allowing the contact lever to be returned by its spring to its normal
position, closing the operating local circuit.
A safety switch, such as is above described, may be combined with many
various lock and block apparatus, such as those in which plungers and commutators
are employed for signalling from one station to another, or in which contact keys,
levers, slides or other handles are employed to transmit currents for unlocking or
releasing points or signals or their levers. In order to combine such a switch
conveniently with existing block apparatus, having operating plungers or com-
mutators, without having to alter the apparatus itself, I pass through or along the
case of the apparatus, a sliding bar having stops or tappets by which movement of
the plungers or commutators is prevented unless the bar be moved, and by this
movement of the bar, the safety switch lever is made to break contact, so that the
operator's local line is no longer available to transmit any safety signal or current
for unlocking or releasing signals, points or their levers so as to cause danger on
the line, during the passage of a train until the normal contact in the safety switch
is restored. It is in many cases of advantage to connect to the lever of the safety
switch a small indicating needle, semaphore signal, or a shutter, to present itself
at an opening of the case so as to indicate the condition of the line to which the
switch is related.
ስስ
CT1002
ABEL & IMRAY,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
A Safety Switch for Electrical Look and Block Apparatus
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 :-
My invention relates to a safety switch arranged in any conducting line for
electrically operating lock and block apparatus in such a manner that when an
operator gives or unlocks a signal or moves or unlocks a set of points or performs
any other operation which leads to the blocking of part of a line by the admission
to it of a train or of a truck or carriage, he at the same time breaks a contact and
thereby renders farther electric operations impossible until the train or the trucks
or carriages have passed a treadle or other appliance on the line, by the action
of which an electric current is made to operate the safety switch so as to restore
the contact.
The safety switch is constructed as shewn in elevation in Fig. 1 of the
accompanying drawings.
A lever A pulled in one direction by a spring B normally takes the position
indicated by the dotted lines A' making a contact at C by which the operator's
local circuit is closed.
In order that the lever A may take and retain this mormal position, a spring
rod D is pushed towards the right by the point or signal lever to which the switch
relates, when that lever is in such position that the signalman can electrically
operate with safety.
When, by moving the point or signal lever, he frees the rod D, this rod, urged
by its spring, moves to the left moving the lever A so as to break the contact C
for the operating local circuit and to make a contact E for the circuit of the treadle
or other appliance on the line, and the lever A thus moved is held in this position
by a catch F, keeping the operating local circuit open, even if the rod D be again
pushed to the right. When the train or vehicle passes the treadle or other
appliance on the line, a current is transmitted to the coil of an electro magnet G
in the safety switch, and its armature H is attracted raising the catch F to the
dotted position F¹ and allowing the contact lever A to be returned by its spring to
its normal position A' closing at C the operating local circuit.
A safety switch such as is above described may be combined with many various lock
and block apparatus, such as those in which plungers and commutators are employed
for signalling from one station to another, or in which contact keys, levers, slides or
other handles are employed to transmit currents for unlocking or releasing points
or signals or their levers. In order to combine such a switch conveniently with
existing block apparatus, having operating plungers or commutators, without having
to alter the apparatus itself, I arrange the switch in relation to such apparatus as
I shall describe referring to Figs. 2, 3, 4 and 5 of the accompanying drawings.
Fig. 2 is a front view shewing the safety switch S placed by the side of the
ordinary plunger block signalling instrument P,
Fig. 3 is a sectional plan,
Fig. 4 is a front view with the covers removed.
I pass through the case of the apparatus P a sliding bar D having stops or
tappets d by which movement of one or other of the plungers or commutators in
the instrument P is prevented, unless the bar D be moved, and, by this movement
of the bar, the safety switch lever is made to break contact, so that the operator's
local line is no longer available to transmit any safety signal or current for
unlocking or releasing signals, points or their levers, so as to cause danger on the

page_text: line during the passage of a train until the normal contact in the safety switch S s
restored.
It is in many cases of advantage to connect to the lever of the safety switch a
small indicating needle semaphore signal, or a shutter, to present itself at an opening
of the case so as to indicate the condition of the line to which the switch is related.
As shewn in Figs. 3 and 4 the sliding bar D is in such a position that its tappet d
prevents the lower plunger p³ from being pushed in, the upper plunger p³ being
then free. Also the bar D cannot be pushed to the left because its end is stopped
by an arm K shewn in section in Fig. 5. When by a signalman at a distant station
an electrical current is transmitted for signalling, the electro magnet G of the
switch attracts its armature H which raises an arm and thereby raises K so that
the operator can now push D to the left. By this movement he releases the
plunger pl and locks the plunger p³, also he pushes to the left a lever L carrying a
contact spring thus breaking the contact at C opening the circuit of the operator's
local line, and making contact at E with a line connecting the magnet Ġ to the
treadle or other contact operated by the passage of a train.
The contact lever L, having thus been pushed to the left, is held in that position
by a catch on a lever M notwithstanding that the bar D has been pulled back.
But when the circuit through E is closed by the passage of a train, the armature H
is attracted raising the arm and the lever M, and thereupon the contact lever L
being released is returned by its spring breaking contact at E and restoring contact
at C.
It is of advantage to provide the safety switch S with a screen which when the
lever L is in its normal position as shewn in Fig. 4 presents the word "Clear" or
its equivalent at the front opening. When the lever L is moved to break contact
at C the screen is moved to the left allowing a red disc behind it to be seen, with
words such as "Train on Line."
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, I declare that what I
claim is :-
―:
1. A safety switch constructed and operating substantially as described with
reference to Fig. 1 of the accompanying drawings.
2. The modified form of safety switch substantially as described with reference
to Figs. 2, 3, 4 and 5.
3. The connection and interlocking of safety switch S with block signalling
instrument P by means of a sliding bar D, substantially as described.
Dated this 16th day of March 1894.
ADEL & IMRAI,
Agents for the Applicant.