An Improved Switch for Telegraphic Transmitting Keys.
Year: 1887

page_text: PROVISIONAL SPECIFICATION.
An Improved Switch for Telegraphic Transmitting Keys.
1. ROBERT MACFIE CUNNINGHAM of 19 Great Winchester Street in the City of
London, Secretary, Western and Brazilian Telegraph Company, do hereby declare
the nature of this invention (a communication from abroad by Thomas Henry Davis
and Charles Peeling, both of Rio de Janeiro, in the Empire of Brazil, Telegraphists)
to be as follows:--
This invention relates to an improved switch for telegraphic transmitting keys used
in long distance telegraphy by means of the siphon recorder or mirror galvanometer;
and it consists of a double switch and connections, replacing two separate switches
generally used, and obviating the danger of the switch being "left over" and of the
operator neglecting to cut the condensers out of circuit before sending, two sources of
much trouble and delay. Besides cutting the condensers out of circuit, the improved
switch also brings a sending shunt into circuit for recording the sending signals when
a recorder is used.
According to this invention, a rock shaft operated by a lever handle is so arranged
that when the sending keys are not being operated, the handle is caused, by a spring,
to occupy such a position as to interfere with the manipulation of the keys so that the
operator must necessarily move it and continue to hold it out of the way in order to
send a message. This rock shaft carries two contact segments insulated from each
other and each adapted to make contact with springs, according as the shaft occupies
the one or other of its two positions, so that, by the act of moving the lever out of
the way and so partially rotating the shaft and segments the necessary change in the
connections is made, whereby the condensers are cut out and earth inserted direct
and whereby also the sending shunt, if used, is brought into circuit for recording
the sending signals. On releasing the lever of the rock shaft, the latter is
returned by its spring to the normal position, thus bringing the condenser again into
circuit.
When using a mirror galvanometer, as there are no sending signals to be
recorded, the shunt may be dispensed with, but otherwise the connections remain the
same

page_text: The contact segments on the shaft are respectively in permanent connection,
through the journals of the shaft, with the "dot" and "dash" keys, the latter being
also connected to the line 'terminal of the instrument. The one segment turns
between a pair of contact springs, of which one is in connection with the condenser
terminal and the other with the earth terminal of the instrument, the segment making
contact with the one or other spring, according to the position of the rock shaft and
lever. The other segment makes contact (at same time that the first mentioned
one is put to earth) with a spring which is in connection with the shunt
terminal.
When receiving, the current passes through the recorder to the line terminal,
thence to the dash" key, thence across the bridge to the other or "dot" key
thence through the one end journal to the segment in connection therewith, thence
through the spring with which the segment then makes contact to the condensers,
and so to earth. When the lever is pulled down for sending the connection of the
last mentioned segment with the condenser is broken and the segment is put to earth
whilst the other segment makes connection with the shunt.
R. F. CUNNINGHAM.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.

page_text: 1 ROBERT MACFIE CUNNINGHAM of 19 Great Winchester Street in the City of
London, Secretary Western & Brazilian Telegraph Co., do hereby declare the nature
of this invention (a communication from abroad by Thomas Henry Davis and Charles
Peeling, both of Rio de Janeiro in the Empire of Brazil, Telegraphists) and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
This invention relates to an improved switch for telegraphic transmitting keys used
in long distance telegraphy with the siphon recorder or mirror galvanometer; and
the invention consists of a double switch replacing two separate switches generally
used, whereby the danger of the switch being "left over" and of the operator
neglecting to cut the condensers out of circuit before sending a message-two sources
of much trouble and delay-are obviated. Besides cutting the condensers out of
circuit, the improved switch also introduces a shunt or resistance by which sufficient
current is diverted through the recorder when one is used for recording the sending
signals. The double switch is carried by a rock shaft and is caused to normally
assume such a position as to bring the condensers into circuit. This rock shaft is
provided with a lever handle which in the normal position of the rock shaft, occupies
such a position as to obstruct the manipulation of the sending keys, so that the
operator must necessarily move and hold it out of the way in order to send a
message. The double switch consists of two contact segments on the rock shaft
which according as the shaft occupies the one or other of its two positions, make and
break certain connections, so that by the act of moving the lever out of the way and
so partially rotating the shaft and segments, the necessary change in the connections
is made, whereby the condensers are cut out and earth inserted direct and whereby
also the shunt is introduced if a recorder be used for recording the sending signals.
On releasing the lever of the rock shaft the latter is returned by its spring to the
normal position, thus bringing the condenser again into circuit in readiness for
receiving a message. When using a mirror galvanometer, as there are no sending
signals to be recorded, the resistance may be dispensed with, but otherwise the
connections remain the same.
Reference is to be had to the accompanying drawings forming part of this
specification, wherein figure 1 is a plan view; figure 2 a side elevation; and figure 3
a front elevation of the sending instrument with the switch in its normal position as for
receiving. Figure 4 is a front view showing the position occupied by the switch
when sending. The same letters of reference indicate the same parts in all the
figures.
A A' are a pair of keys for producing the signals corresponding to the "dot" and
"dash" elements of the Morse code, the keys being carried by spring arms and
playing between pairs of contacts a a a¹ a¹* carried by a metallic bridge B, and by
the base board, the keys resting normally against the bridge contacts a a¹ in the
usual manner. D is the rock shaft journalled in end brackets d, and the lever arm
by which the rock shaft is moved in one direction passes up between the keys and is
provided with a cross-bar or handle D' which when the lever is in its raised position
lies over the keys A A' in the way of the operators fingers, but which may be
conveniently held down out of the way by the same hand that operates the keys, the
lever being kept in the raised position by a spiral spring D³ connected to the lever
arm and to a fixed point. F. G are the contact segments mounted near the ends

page_text: of the rock shaft and insulated from each other, these segments being in permanent
electrical connection through the journals of the rock shaft and through contact
springs d d pressing against the ends thereof, with the keys A A¹ respectively, the
latter key being also connected with the instrument terminal I. The segment is of
the form shown in figure 5 and turns between two opposite contact springs ce in
electrical connection with the condenser terminal and the earth terminal E
respectively, the segment making contact with the spring only when the lever D'
is raised (as in figures 1, 2, 3) and with the spring e only when it is depressed (as in
figure 4). The segment G makes contact only when the lever D is depressed with a
springs which is in connection with the shunt terminal S. When receiving, the
current passes through the recorder to the terminal I thence to the right hand or
"dash"key A¹ thence by contacts a a¹ and across the bridge B to the left hand or
"dot" key A thence through the spring d and the end journal of the shaft against
which it bears, to the segment F, thence through the spring e with which the
segment then makes contact, to the condenser terminal through the condensers to
earth. When the lever D₁ is depressed for sending a message, the shaft D is
partially rotated, so that the connection of segment F with spring c is broken (thus
cutting out the condenser) and contact made with spring e through which the
segment is put to earth at same time that segment G makes contact with
springs, thus bringing into circuit, the shunt or resistance coil through which the
major part of the current passes direct, to the line, sufficient only being diverted
through the instrument to record the sending signals.
The zine pole Zn of the battery is in connection with the lower contacts a* a¹*
and the copper pole Cu with the bridge B and its contacts a a', so that when the
key A is depressed, the zinc pole is to earth through the key A and contacts Fe;
and the copper pole to line through the bridge B, the key A¹ contacts Gs, terminal S
and the shunt, and also through terminal I and the recorder. When the key A¹ is
depressed, the direction of the current is reversed, the zinc pole being then to line
through the last mentioned connections and the copper pole to earth through the
bridge B, key A, and contacts Fe.
If a mirror galvanometer is used the connections remain the same, but there are no
resistance coils between, the line terminal L of that instrument and terminal S
and consequently the signals will go direct to the cable without influencing the
galvanometer.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed I declare that what I claim is-
1. The combination with a telegraphic transmitting instrument such as herein
described, of the herein described double switch consisting of the two contact
seginents carried by a rock shaft, and the corresponding contact springs and their
connections with the different terminals of the instrument, arranged and operating as
and for the purpose herein specified.
2. In the herein described double switch for a telegraphic transmitter, the combi-
nation with the rock shaft carrying the contact segments of a spring for actuating it
in one direction and a handle for operating it in the other direction, the handle
being arranged in relation to the transmitting keys substantially as and for the
purpose specified.
Date : 1911
1007
R. M. CUNNINGHAM.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.