Improved Electric Switches and Transmitting Apparatus for use in Telegraphic or Telephonic Systems.
Year: 1890

page_text: COMPLETE. SPECIFICATION.
[Communicated from abroad by MICHAEL SCHWABACHER, of Frankfurt-on-the-Maine,
in the Empire of Germany, Manufacturer.]
Improved Electric Switches and Transmitting Apparatus for use in
Telegraphic or Telephonic Systems.
I, GEORGE MACAULAY CRUIKSHANK C.E. of 62 Saint Vincent Street, in the City
of Glasgow, Registered Patent Agent and Fellow of the Institute of Patent Agents, do
hereby declare the nature of this invention and in what manner the same is to be
performed, as communicated to me, to be particularly described and ascertained in
and by the following statement :-
This invention has for its object, when conversation is carried on in a telephonic
system or installation between neighbouring localities over a common central point,
to render the co-operation of persons at the central point unnecessary and to enable
the persons connected to the local, that is, to the different lines to themselves make
the necessary connection when required.
The invention applies in a similar manner to telegraphic communication, as it
enables an office to be directly connected to neighbouring localities, the connections
to. which could not be hitherto obtained without the intervention of an attendant in an
intermediate office.
This arrangement differs essentially from those in which several offices are
connected to the central point by means of a common circuit where the making and
breaking of the connections is dependent upon an attendant placed thereat, and
where it is necessary, when the traffic is ended, to have a special rearrangement or
resetting upon the position of rest. The novel arrangement or installation is so
designed that besides giving automatic communication, not only are the connections
prevented. from being disturbed by a third but the return to the position of rest
follows independently the great advantage gained being that the connections with the
places called up can be automatically severed after the traffic is over. The working
power heretofore required for such communication becomes therefore superfluous and
irregularities of time occurring in the making and breaking connections between the
desired points are obviated.
For simplicity the invention is described and illustrated on the two accompanying
sheets of drawings as applied to the telephone system only.
Figure 1 is a front elevation of one of a series of 16 switches and transmitting
apparatus connected together and operating to control the connection between 16
different telephonic circuits in accordance with this invention.
Figures 2, 3, 4, 5 and 5" are side elevations partly in section of several parts of
the series.
Figure 6 is a front elevation and
Figure 7 a back elevation of the mechanism contained in the body of one of the
switches.
Figure 8 is a back view of the disc forming the front of the above mentioned series
of switches.
Figure 9 is an elevation,
Figure 10 a vertical section and
Figure 11 a plan of a key to be used in operating the switches.
Figure 12 is a diagrammatic view showing the connections between the series of
switches and transmitting apparatus.
To attain the object of the invention instead of the ordinary cases for each
telephonic circuit switches or intermediate mechanism w¹, w², w³ &c. (Fig. 12). are.
made use of. The required number of switches are. assembled in a small box or case
and arranged in a row behind one another. An installation of 16 telephonic posts

page_text: .
or omces 13 described by way of example, their intercommunication being carried
out by means of 16 switches. Each switch is formed of a bobbin such as M (Fig. 1)
which acts simultaneously as an electro-magnet and as a commutator. The bobbin
has a double wire winding, the end of one of the wires being attached to the binding
screws a¹ and el while the ends of the other are secured to the screws a² and e².
The core of the bobbin contains two tubes of soft iron, and the filling of the core
around these two tubes consists of thin iron rods.
The upward prolongation of this filling forms the pole p. The horse shoe
magnet S N is carried by the brass plate oo connecting the two brass pillars q' and q
and its branches extend through two openings of the plate o o insulated by ebonite
blocks from the pillars q' q². The polar surfaces S and N are provided with notches
in which are placed the oscillating points of the soft iron armatures sn whose rise is
regulated by set screws 1 to 1 tapped through brackets on the pillars q q² the
brackets E¹ and E2 being insulated from the pillar 2 by means of ebonite blocks.
The lifting or pulling springs f1f2 are designed to regulate the armature according
to the action of the current.
The screws in the support T of the magnet SN and which carry the springs f1f2
permit the magnet to move up or down within small limits for the purpose of
regulation, the arms t, t, of the support T and the openings in the plate o o serving
jointly as guides. The binding screw a² is electrically connected through q² and the
wire d with the armature s while the screw e2 is connected through the body of the
switch hereinafter more fully described with the index. Z of the same.
The bracket E upon the screw 3 of which the armature bears in its resting
position, is connected to earth while the bracket E¹ is connected with the negative
pole of a battery B (Figs. 1 and 12) common to all switches and whose other pole is
connected to earth.
A
The switch is so arranged that on the passage of a positive current proceeding from
the circuit (for instance circuit 1) through one of the wire coils a¹ el to earth, the
arimature n is attracted by p while a negative current proceeding from the same
source and passing in the same direction through a' e¹ to earth causes the armatures
to be attracted by p and the prolongation of the armature s bearing against the
contact of the battery B a current is immediately sent from the battery into
required circuit (say circuit 9) the said current passing through the armatures.
and the mechanism (g² y z &c. Figure 5) which is hereinafter more fully described.
The second winding is meanwhile open along the mechanism d q² a² e².
telephonic current passing from the calling circuit 1 through the winding a¹ e¹ to
earth is transmitted by induction through the neighbouring winding a² e². The
current waves generated thereby in the latter winding arrive on
one side
through a² qd 3 and E2 and on the other through e², body of the switch, index Z,
circuit called upon (for instance circuit 9) and through the hearing apparatus to
earth. The telephonic (speaking) current from circuit 9 is reversely transmitted
through Z, the body of the switch, and from the coil or winding e² a² which is
connected to earth through q²d E2 by induction into the coil or winding e¹ a¹
whence it reaches the calling circuit, the communication being thus established.
The two brass rods g' g² of the armatures s and n (Figs. 3, 6 and 7) extend into
the switch mechanism below through the two before mentioned soft iron tubes placed
in the core of the commutator electro-magnet M. To prevent the fortuitous
transmission of currents (issuing for instance from the call battery. B) the two
rods g¹ g² are furnished with an insulated coating from the armatures down to where
they protrude from the small soft iron tubes. The rod g¹ carries an arm a which is
adjustable in a slot and is firmly clamped by means of a pinching screw. The lower
end of the rod g¹ when the switch mechanism is at rest enters between two teeth
on the insulated wheel R, mounted upon the axis.x. A pawl situated on a pin c
insulated from the brass piece w and held down by a spring also insulated from the
said piece engages with the wheel a few teeth further round than the rod gl. The
cylindrical piece z connected with the wheel R is of a diameter slightly less than the
diameter of the wheel at the roots of the teeth only a single tooth of the wheel

page_text: being cut to the depth of the circumference of the cylinder. The wheel R with its
cylindrical projection is firmly keyed upon the axis being placed between the
two bearings of this axis that is to say between the brass standard v and the brass
crank piece w.
The axis which passes at one end through the centre of the dial uu
and carries at that point the index Z is furnished at its other end with the steel disc i.
The spiral spring F on the axis a imparts to it a slight turn and presses the index Z
against the projection or stop l, its object being hereinafter more particularly
described. A semi-cylindrical block y is mounted in jaws made in a bracket w and
between other jaws on the saine bracket there is centred the axis of a disconnecting
lever h (Figure 3) whose longer arm terminates in a hammer Q which is situated
opposite or in line with the disc i on the shaft a. The opposing surfaces of the disc i
and of the hammer Qare grooved or serrated radially. The semi-cylindrical block y
has a flat part y₁ on which the short arm of the lever rests. As often as the
polarized armature n is attracted by a positive current the rod gl through the
intervention of the wheel R displaces the index Z and the wheel being in the present
case furnished with 16 teeth will cause the index to travel over a th part of the
circumference of the dial u u. A negative current which follows a similar direction
and proceeds through the same coils or winding a¹, e, attracting now the other
armatures causes half a revolution to be imparted to the block y by means of the
rod g². This motion throwing out the upper end of the lever causes the hammer Q
to push the shaft forward with its toothed wheel and index or pointer and to
simultaneously engage the serrations upon the disc i and hammer Q with one another.
This operation has for its object to prevent the spring F from turning the axis
and its index back to the position of rest when the pawl k and the rod g' are
disengaged from the teeth of the wheel R. The rod g' and pawl k after the forward
sliding motion of the axis are over the smooth cylindrical projection z upon.
which k but not g' fully bears (see the position in Fig. 5). As soon as a positive
current has again depressed the rod g¹ its arm a pushes the half cylinder back into its
position of rest. At this moment, the tension of the spring acquired during the
forward motion of the shaft r acts in a rear.direction, so that follows this backward
action without the surfaces and Q becoming disengaged in the meantime. After
the shaft has moved so far back that the pawl k coming in contact with the side of
the wheel R will not allow further backward motion, a spring b¹ (Fig. 3) disengages the
serrated surfaces of the disc i and hammer Q whereupon the index Z is by the
turning action of the spring F brought back against the stop l. When this
movement is completed the individual tooth in the wheel R which is cut as before
mentioned to the depth of the circumference of the cylinder z is opposite the pawl k
which then enters it whilst the rod g' enters the teeth of the wheel R higher up.
In proximity to the periphery of the dial uu covered with insulated material are
formed the required number (16 in the present instance) of perforations for thin
steel rods 1, 2, 3, 4-16 which pass uninterruptedly through all the dials of the
switch mechanism w, w²-16 arranged behind one another. To prevent the rods
from turning upon their longitudinal axis they are made slightly elliptical in cross
section this form being likewise adopted for the perforations which they have to
enter. Behind the last switch mechanism the rods pass through holes in a wooden
disc P (Figs. 5 and 12) against which is pressed a stop (or nut m for common use)
on each rod by means of a weak spiral spring arranged behind the disc and operating
backwardly. The disc D (Figs. 2 and 8) is placed in front of the switch w (Fig. 2)
in such a manner that the rods 1, 2-16 pass through the holes arranged in a circle in
the disc the ends of the rods coming in contact as shown with the ivory keys or
pegs L° which are firmly fixed upon the spring blade L. In the resting position as.
at L the spring blade connects the binding screws 0° and u° while on the
contrary when the rod is pushed forward (as at 1) the spring blade is first raised
from O, in order to prevent_short circuiting through M and is then electrically
connected with the rod 1. Each rod 1, 2, 3-16 has in front of the dial uu a
short metal projection v v²-16 arranged radially from the centre. These
projections are omitted on rod 1 in front of the dial of the switch w¹ on

page_text: rod 2 in front of dial of switch c², on rod 3 in front of dial of switch w³, and so on
to rod 16 in front of dial of switch to where the index Z of each switch is in its
position of rest and at the points where these projections are omitted the respective
rods are provided with an inner finger or spur v Figures 3, 5 & 7 which serves to
limit the forward motion of the rods. As long as the index Z of each switch remains
at rest it presses on a short lever suspended ontside the dial u u from a spindle
passing through the dial and carrying a block K on its other end said block K being
held by the pressure of the index Z on the lever back to a stop pin 12 against the
pressure of a spring in which position the rod corresponding to that switch is free
to move forward under the action of any other of the switches. But when a circuit
(for instance circuit 9 see Figure 5) is connected to another for speaking purposes
(here with circuit 1) the index having left its position of rest the block K is
removed by the spring in between the rear of the dial uu and the inner finger or
spur v of rod 9 so that rod 9 cannot be moved forward from its place and brought
into communication with circuit 9. A commenced conversation therefore cannot be
interrupted or heard from any other place. Each index Z is made of metal and
carries a counterweight C upon its short arm whilst on its longer arm there is secured
a bent or kneed ivory or ebonite piece J. The metallic extremity of the longer arm
moves freely behind the projection Y while the kneed piece J moves in front the
projections v resting against the inner surface of the piece J. If now owing to the
forward motion of the index (say of Z Figure 5) placed in circuit 1 the rod 1 is.
pushed forwards the spring blade L' being thereby raised in the disc D, all the
projections of the rod 1 will be likewise moved forwards and were it attempted to
establish another circuit upon 1 the piece J on the index on turning would come in
contact with the projection v and prevent the establishment of the circuit. A circuit
by means of which a conversation is already carried on cannot therefore be
simultaneously employed for a similar purpose, so that here also interruptions or
simultaneous hearing are fully prevented. It will be obvious that inter-communication
by means of existing connections between the various circuits whether intermediate
or outside is in no wise limited. Thus if a person on circuit 1 wishes to establish a
connection with a person on circuit 9 he must first send 8 separate positive currents
through switch 1 these currents through the action of the pole piece n, rod gland.
wheel R will turn the index Z round to the rod 9. A negative current now sent in
the same direction will depress the pole piece s and through the action of the rod g³,
block and lever will push forward the spindle a index Z and rod 9, and connect
said rod through the spring L" with line 9. The speaking currents pass from line 1
to the block U through the spring L to the block O' thence through the coil a¹ el to
earth. The currents in the coil a' e¹ induce currents in the coil a² e² said induced
currents passing on the one hand through a qd r³ and E2 to earth, and on the other
hand through 2, the bracket spindle a index Z' rod 9, spring L' and, block U° to
line 9 and through the hearing apparatus to earth.
The diagrammatic view, Fig. 12 shewing the passage of the currents illustrates the
case in which circuit 9 is called upon by circuit 1 and connected therewith. For
severing at the end of a conversation the connection established in Fig. 12 a positive
current must be sent through the circuit 9 into the circuit 1 the arm a of the rod g¹.
in the switch w¹ striking, the half cylinder y and moving it into its position of rest,
the severance of the connection follows in the manner described.
In order to be able to send with certainty the required number of positive currents
followed by a negative current serving to establish the connections the microphonic
boxes at the connected speaking posts are provided with a key of peculiar construction
(Figs. 9, 10 and 11). The peculiarity of the arrangement consists in the key sending
when the double rail y¹ and 8' is depressed and turned down to the right hand side
a number of positive currents in the circuit, while by this manipulation the other pole.
of the battery is at the same time connected to earth. When the pressure ceases and
the key is allowed to return to its normal position or state of rest a reversal of the
poles is effected, so that now the positive pole of the same battery is connected to
earth and by means of the pressure knob # arranged on the side. A negative.current.

page_text: is ready to be sent to the circuit. When this current is sent a cypher disc is
brought back automatically to zero.
T
The arrangement is chiefly as follows:-In a wooden box are firmly fixed the
metallic rings 1, 2, 3, 4 which are arranged concentrically and are insulated from
one another by an ebonite block while ring 1 is constantly in metallic connection with
ring 3 and ring 2 with ring 4 as shown in Figure 10. In the hollow space within
the metallic ring 4 is placed the ebonite core B fitted at its lower end with the
ebonite discε E. The latter has on the under surface 4 notches separated from one
another the distance of a quadrant and formed like ratchet teeth so arranged that a
turn of the core to the left hand side is prevented by a pin on the lever of the pressure
key arranged below and acting as a pawl as shewn clearly in Figure 10. The
upper surface of the disc && is provided with 4 pins 77 corresponding to the four
notches on the underside these pins having for their object to drive the toothed
disc n placed at one side. The metal pegs y and & insulated from one another, are
imbedded in or secured to the core 3. The first peg projects below the core ẞ and
the disc && and is capable of turning in a metal footstep so as to form with its
lower end the axis of rotation for the whole core By 8. The peg 8 is terminated by
a ring placed over a neck formed on the core between 3 and E. The two vertical
pegs and are provided each with a forked end and in these forks are carried the
oscillating points of the key bars &¹ and y'. The free extremities of these two bars
are of unequal length so that the contact screw in the end of the bar ¹ rests upon
the metal ring 4 and that in the bar y¹ rests upon the ring 3. At the opposite ends
the above mentioned bars are connected by means of an insulating piece à to a handle.
Each bar is provided with a second contact screw which is placed upon & above the
ring 1 and upon y₁ above the ring 2. A strong spiral spring blade operating
upwardly holds the key lever normally in the position shewn in Fig. 9. Referring
to the diagram (Fig. 11) shewing the directions of the currents in dotted lines in
connection with the key and supposing the bars & and y₁ in their position of rest
upon the annular rings 3 and 4, the current passes from the battery pole = through
the binding screw Z, ring 3, bar y¹ and peg y proceeding to the working contact
(see Fig. 10) while at the same time the current from the other pole passes through
the binding screw K and the annular ring 4 through the bar & and peg & which
with its annular end surrounds the neck of the core ẞ and slides in contact with a
spring connected with the binding screw E from which the current is led to earth.
By pressing the knob when the double bars are in their normal position the inner
end of the lever of the knob 7 is brought into contact with the contact piece
there will be a negative current in the circuit. When the double bars are pressed
down by the common handle the pole 2 is connected to the ring 3 which is in
constant contact with the ring 1 and thence through 81 and 8 to earth while the
connection from the other pole is through the annular piece 4 which is in constant
contact with the annular piece 2 whence it proceeds along y and y¹ to the workin
contact of the inner end of the key w. An annular piece rrr arranged upon the
upper surface of the wooden box is provided with an edge bent over at right angles
and which has 4 recesses corresponding to the like number of cam surfaces on the
underside of the disc . By pressing down the handle when over one of these
recesses the stud of the insulating piece connecting the two key bars sinks until it can
slide below the section of the projecting edge between two recesses and by
turning the handle to the right the stud sliding under the said projecting edge
causes the outer screws to be in contact with the rings 1 and 2 until the next recess
is reached, whereby a first positive current is despatched the inner end of the key
being held in contact with the piece by means of the can surfaces on the lower side
of the discs. The movement to the following recess causes a second positive current
to be sent and so on. As during a complete revolution the key is pressed four
times upon by the four cam surfaces of the disc whereby a positive current
passes each time through the circuit binding screws and the connected circuit to the
distant switch, the latter will be intercalated after say 2 revolutions of the key in
circuit 9. Should a pressure be applied to the knob after the release of the lever
and

page_text: a negative or zinc current passes through the switch and causes the motion of the
rod 9 in the manner above described. The four pins upon the upper surface of
the ebonite disc & each turn the disc the distance of a tooth against the pressure
of a spiral spring the backward motion of which the disc being prevented by a pawl
and ratchet arrangement (Fig. 10). The disc n is figured or numbered on the
periphery and during this rotation the figures are exposed successively at a slot in
the side of the wooden box through which to shew the connections in the order
corresponding to the course of the index Z upon the various connections (for
instance 9, 10, 11-16, 1, 2-8) thus the number of the connection reached when turning
the key can be read at any moment on the disc. When pressure is applied upon the
key Ta pushing motion of the rod & follows and its wedge shaped end raises the
pawl from the figure disc n the said disc n being brought back through the resilience
of the spiral spring to a particular point of the periphery which is marked zero or 0.
This backward motion is limited by the pin which running in a groove on the
under surface of the disc nabuts at against a swelling on the same.. As soon as
a conversation is ended, the first positive current sent causes the proper call number
to be exhibited indicating that the connection in the distant switch is severed again.
By applying the above arrangement for telegraphic purposes the armatures of the
switch must be made to work as for transmission relays after the connection with the
desired branch circuit has been effected by the arinature n.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me,
I declare that what I claim is :-
1. The use of a number of electro-magnetic systems arranged to act as commutators
for telephonic currents and at the same time as transmitters of equal currents with
two polarized armatures each armature working separately upon a switch for inserting
any suitable number of circuits passing over a common central point D (Figs. 2
and 8) further the art of combining the arrangement with connecting rods common
to all switches and capable of being thrown out of gear, and at the same time with
other mechanism connecting in such a manner that the said connecting rods are
automatically brought back to their normal position when the connection is severed
substantially as described with reference to the drawings annexed.
2. The arrangement of the peculiar key hereinbefore described whose depression
and rotation sends at each complete revolution four currents of determined direction
in the circuit the second pole of a battery connected thereto being conducted during
such revolution to earth or to the return circuit, the key on pressure being withdrawn
causing a reversion of the poles of the battery to be effected at a given recess r³, in
order to enable one currents of a direction contrary to that of the former to be sent
in the circuit by means of a knob (7) pressure on which causes an indicating disc
turned during the above mentioned revolution to be automatically brought back into
its normal position, substantially as set forth with reference to the appended
drawings.
Dated this Eleventh day of February 1800.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.