Improvements in Automatic Calling Devices for Telephone Exchanges.
Year: 1898

page_text: Date of Application, 11th Jan., 1898-Accepted, 19th Mar., 1898
COMPLETE SPECIFICATION.
Improvements in Automatic Calling Devices for Telephone
Exchanges.
A communication by THE STROWGER AUTOMATIC TELEPHONE EXCHANGE, of
No. 947-949, Rookery, Chicago, in the County of Cook and State of Illinois,
United States of America.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign Patent
Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in the
County of Lancaster, 118, New Street, Birmingham, in the County of Warwick, and
322, High Holborn, in the County of Middlesex, Civil 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 :—
This invention relates to means for transmitting electrical impulses over a plurality
of lines by means of a step by step circuit breaker and a circuit changer, and which
may be employed in combination with automatic telephone exchange systems
whereby a person at one station may intermittently energize a plurality of electro-
magnets, one at a time, alternately, or in some other desired order at some distant
station, and the object is to provide a construction for this purpose which consists
of a series of movable finger holds of which some one is moved up to a stop and
then released, there being an indicator connected therewith to show which one of a
plurality of electro-magnets is in connection with the line wires.
The finger holds are disposed, in this instance, in circular order concentric with a
shaft, which latter is adapted to revolve by the action of a finger engaged with some
one of the holds and operating against the resiliency of a spring, which latter is wound up
a different amount for the movement of each finger hold, and when any particular
finger hold has been moved up to a stop and then released, the tension of the spring
causes the parts to return to the normal position, limited by an escapement
mechanism to a moderate rate of speed, and causes a switch in this return movement
to serve as a medium through which an intermittent current of electricity is
transmitted through a particular one of a plurality of wires each connected to a
motor magnet to be energized, as may be desired, and as is described hereinafter and
illustrated in the accompanying drawing, in which—
Figure 1 is a front elevation showing the parts which are ordinarily visible when
applied to an automatic telephone exchange system.
Figure 2 is an inside or rear elevation, showing the greater part of the switching
apparatus.
Figure 3 is a plan showing the operative parts in the same relative position as
indicated in Figures 1 and 2.
Figure 4 is an elevation of the front case with a portion broken away to show
method of applying indicator for designating the particular magnet being energized.
Figure 5 is a front elevation showing the finger hold plate and magnet indicator,
as they appear when the front case is removed.
Figure 6 is a plan of the hollow actuating shaft, the pivoted support therefor,
which is part of the frame of the device, being broken away, but the finger hold plate

page_text: and the escapement wheel which are attached to the actuating shaft, and the magnet
indicator, and the segment of cogs for operating the magnet indicator, are all shown
of
in the elevation, the shaft connecting the magnet indicator and segment
cogs for
operating the same being shown in broken lines concentric with the actuating shaft
through which it is disposed, and in which it partially rotates.
Figure 7 shows, respectively, a rear elevation and a plan of the combined escape-
ment and switch actuating wheel, which, when in the operative position, is firmly
attached to the inside end of the actuating shaft. Figure 7 also shows an actuating
pawl, pivotally mounted in a bracket, which latter is secured upon the escapement
wheel.
Figure 8 is a rear elevation of the frame in which the rear end of the actuating
shaft is pivotally mounted, and to the side of which is pivotally mounted a detent
which is hereinafter referred to.
Figures 9 and 10 are, respectively, an elevation and a plan of the pallets of an
escapement device, which are also shown in Figure 2 in engagement with a series of
pins near the periphery of the escapement wheel.
Figures 11 and 12 are detached perspective views of the pallets shown in the
escapement device, Figures 9 and 10.
Figure 13 is the operative mechanism of a make and break switch, which operates
to transmit a current in only one direction of the movement of the pins of the escape-
ment wheel.
Figure 14 is a diagrammatic view showing the connection between the calling
device and the magnets of an automatic telephone exchange, together with the usual
battery and ground connections. Similar letters indicate like parts throughout the
several views.
In Figures 1 and 2 the mechanism is shown mounted on a door A, which may
form the cover or front of a shallow box to contain the mechanism shown in Figure 2
when the door is closed.
As shown in Figure 6 the hollow shaft B is mounted to revolve in a metallic
bearing B', which forms a bushing disposed centrally through the box lid A, the
hollow shaft terminating at the front end at B2, and at the inside end at B³.
At the front end of shaft B is firmly secured the disc C, around one side of which,
near the margin, are disposed ten projections or finger holds such as C, and beginning
at the bottom each finger hold is designated by a different numeral from 1 to X,
inclusive, in arithmetical order.
Close to door A, near the inside face thereof, is securely mounted on shaft Ba
wheel D, Figure 7, and the outer end of shaft B projects through a hole E¹ in
frame E, Figure 8.
Between frame E and wheel D is a volute spring F, which is attached at one end
to a pin at E2, near the lower end of frame E, the spring being partially wound up to
hold wheel D and the finger hold disc C in the normal position shown, with the stop
bracket D¹ of wheel D against an adjustable stop screw D2 in a lug attached to
frame E, Figures 3 and 7.
Wheel D is provided with a series of pins G, disposed at equal distances apart, near
the peripheral edge thereof, which serve a double purpose, first, by engaging with the
pallets Hand H' in one direction of their movement, which is limited thereby, and
for operating a switch I against a pin 13, which is connected with battery J. The
pallets and the switch form the main part which shall be called a step by step circuit
breaker.
The pallets H and H¹ are both pivotally mounted upon the same pin, and pallet H
is provided with an arm to which a weight H2 is attached, and with a spring H³ which
holds a prolongation of pallet H against a pin H+, so that, in action, when the pin
wheel D is turned in the direction indicated by arrow 7, the pins G will press the end
of pallet H aside, and the prolongation away from pin H of pallet H¹, and bend
spring H³ downwardly, without disturbing the other pallet or its weight H2, but
when wheel D is turned in the direction contrary to that indicated by arrow 7, pins G
will contact the inside face of pallet H and force it downwardly, and cause the

page_text: prolongation thereof to contact pin H' and vibrate pallet. H¹, together with the
weight H upwardly, when pallet H' is contacted successively by pins G which are
successively retarded in their movement by the rapidity of the vibrations of the
pallets, which vibrations may be easily changed in speed by shifting the weight H2
on the arm of pallet H¹.
The amplitude of the vibration of the pallets is limited by pins H³, which are
contacted by the weight arm of pallet H¹, at the limits of movement. The switch
arm I is attached to a boss I¹ which is pivotally mounted on a pin, aud is electrically
connected with frame E.
Attached also to boss 1¹ is an arm I², whose free end is shaped as shown in
Figure 13 so that the pins G will vibrate it in a direction to cause switch arm I
to move from pin I³, which latter is connected with battery J, Figure 14, when
wheel D is turned in the direction indicated by arrow 7, but switch arm I will vibrate
and make and brake contact with pin 13 once for each pin G which contacts arm I²,
when wheel D moves in the opposite direction indicated by arrow 7, the resiliency of
spring I, with its outer end between two pins and its inner end attached to boss I,
serving to normally hold the switch arm I out of contact with pin I³, and the free
end of arm [2 midway between the limit of its vibrations.
Mounted on a pin attached to frame E, and in electrical connection therewith, is
ratchet wheel K, which has a helical spring K¹ attached at one end to the boss thereof,
and the other end to the pivotal pin, and the ratchet wheel is limited in its motion
when actuated by the spring to the normal position by a projection therefrom
contacting a pin K2, Figure 2.
At L is pivotally mounted upon wheel D, in stop bracket D', a pawl whose free end
is adapted to engage the teeth of ratchet wheel K.
At I is a forward projection from pawl L, which contacts the teeth of the wheel
and lifts the hook of the pawl out of engagement with each ratchet tooth, after it has
moved the wheel more than the pitch of one tooth.
A detent M, Figures 2 and 8, serves to hold the ratchet wheel in the operated
position. Attached to the face of ratchet wheel K are seven pins, which serve as cog
teeth, and four of them contact points for spring switches P and P¹. Said wheels, pins
and switches form what shall be called the circuit changes.
Pins N, N1 N2 and N³ are of metal and in electrical connection with the frame E
through ratchet wheel K and its pivotal pin, but pins 0, 01 and 02 are of insulating
material, or, are too short to contact with spring switches P and P¹.
Spring switches P and P¹ are insulatingly attached to frame E.
At Q is a bent arm, projecting from detent M, which is in line with the detent of
the telephone hook lever, indicated by broken lines Q1, Figure 3, which action releases
detent M when ratchet wheel K, if it has been moved forwardly, is free to turn back
by virtue of spring K¹ to the normal position.
The means for indicating what call has been made, and whether the telephone
exchange is in the normal condition, consists, in this instance, of the segment plate R,
which is marked with the abbreviations and words "
<
"Tel.," Hund.," 66 Tens,"
"Units" and "Out," and is securely fastened to front end of shaft R¹, which is
disposed through the axial portion of the shaft B, and has attached to the inside end
a segment of cogs R2, which is engaged by the pins N, O, N1, N2, 01 02, and N³ of
ratchet wheel K.
The entire front of the finger hold disc C is covered by a case S, with the exception
of the right hand side where are exposed the finger holds C¹, and at Si where there is
an opening through which the abbreviations and words "Tel.," Hund.," etcetera may
be seen, successively, as they are brought into register therewith.
6
The case S projects outwardly sufficient to permit the finger holds C¹ to pass in
under the front plate of the casing, and in under the segment plate R, in rotating the
finger hold disc, the casing serving as a stop for the finger at the shoulder S³,
Figures 1 and 4.
To illustrate the application and operation of this calling device in an automatic
telephone exchange system, where each exchange machine is provided with a plurality

page_text: of electro magnets, and each of said magnets is adapted to perform a separate
function, Figure 14 will be referred to, which is a diagrammatic view of the calling
device in electrical connection with an automatic telephone exchange at a central
station, which exchange is represented by one electro-magnet U adapted to rotate
the switch shaft V and another electro-magnet U₁ adapted to slide switch shaft V
longitudinally, in the operating of switching.
In operating this device when connected with an automatic exchange having
a plurality of magnets on the decimal system, for an instance, it is desired to set the
exchange machine to communicate with telephone exchange machine and telephone
number 456, the operator inserts a finger in contact with finger hold number 4,
which is pulled down around in the direction indicated by arrow 7, Figure 1, until
the finger contacts the shoulder of the case S at S2, when the finger is withdrawn,
which releases the finger hold disc C, and the connected wheel D, when spring F will
return the parts to the normal position, but, in the meantime, the pawl L at the
beginning of the motion of wheel D, being in engagement with ratchet wheel K,
has turned this wheel equal to more than the pitch of one tooth, when detent M
drops into engagement behind one of the teeth, and holds the wheel in the partially
turned position, after the pawl L is forced to slip off the engaged tooth by the action
of the projection L¹ thereof, as described, which partial movement of ratchet wheel K
moves contact pin N' around in touch with spring switch P, and causes segment of
cogs R to turn an amount equal to the pitch of one tooth, which removes the
abbreviation "Tel." from the opening S and moves into its place the abbreviation
"Hund."
During the time the operative parts are being returned to the normal position, the
switch arm I is made to contact pin I³ four times, because there are four pins G on
wheel D adapted to strike arm 12, in this return movement, when current is
transmitted four separate times from battery J through wire W, switch I, thence to
contact pin N, spring switch P and line wire X, and magnet U to ground, thus
energizing this magnet four times. Next, a finger is inserted in contact with finger
hold number 5, which is turned around to the stop shoulder S2 and released, when
pawl L will have turned ratchet wheel K one tooth more, which will bring contact
pin Ns into contact with spring switch P¹, and contact pin N¹ out of contact with
spring switch P, and turns segment R² one tooth which moves the abbreviation
"Hund." from opening S and into its place the word "Tens," and during the
time the parts are returning to the normal position, switch arın I is made to
contact pin I³ five times by the action of five pins G, which register with the
five finger holds C¹ from the beginning, when current is transmitted five
separate times from battery J through wire W, pin I³, switch I, thence
through frame E to the contact pin N³, spring switch P¹, wire Y and magnet U
to ground, thus energizing magnet U five times. Next, a finger is inserted in
contact with finger hold number 6, which is pulled around to stop shoulder S²
and released, when, in the same manner as before described, ratchet wheel K is
moved around one tooth, which engages contact pin N with spring switch P, and
disengages spring switch P from contact pin N³, and segment cog R2 is turned
one tooth, which changes the word "Tens" at opening S¹ to "Units," and in the
return of the operative parts to the normal position, switch arm I is made to
contact pin I³ six times, when current is transmitted six separate times from
battery J through wire W, switch I, thence to pin N, spring switch P, wire X and
magnet U to the ground, thus again energizing this magnet, but, six times, instead
of four times as in the first instance.
When, by the action of pawl L, the ratchet wheel K has been turned around
to the hundred point, any additional manipulation of the finger hold disc causes the
pawl to turn ratchet wheel K the pitch of one more tooth, when "Out" will be
substituted for "Units" at opening S, which is to indicate that the telephone has
been entirely disconnected electrically and must be released in order to again be
operative, which release is accomplished by hanging up the telephone receiver on the
hook of the usual telephone lever, shown in broken lines Q1, Figure 3, which lever, in

page_text: descending, contacts bent arm Q projecting from detent M, which latter is released
from ratchet wheel K, which, being free, is revolved backwardly by spring F to the
normal position, with the stop projection thereof in contact with pin K, Figure 2,
and with the finger holds in the normal position shown in Figure 1, from which
position the parts may again be operated as herein before described.
When ratchet wheel K is turnel around to the position when the word "Out"
shows an opening at S¹, the stop projection thereon is in such a position that it is
struck by projection L', at each additional thrust of the attached pawl L, which
latter is lifted by this action and prevented from further operating the ratchet wheel,
should the finger hold disc be additionally manipulated by a careless operator.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed, as communicated to me by my
foreign correspondents, I declare that what I claim is:
1. In a calling device for telephones, the combination, with a series of finger holds,
of a make and break device common to all of the finger holds, said make and break
device being adapted to control the operating mechanism of the exchange
substantially as set forth.
2. In a calling device for telephones, the combination, with a series of finger holds
arranged in numerical order, of a make and break device common to all of the finger
holds, said make and break device being adapted to operate the switching mechanism
at the exchange in harmony with the finger holds, substantially as set forth.
3. In a calling device for telephones, the combination, with a series of finger holds,
of a make and break device, a series of electro-magnets connected therewith, and
means for passing a current of electricity through either of the magnets, substantially
as set forth.
4. In a calling device for telephones, the combination, with a series of finger holds,
of a make and break device, a series of electro-magnets, and means for passing a
current of electricity through either one of the magnets by means of the said make
and break device, substantially as set forth.
5. In a calling device for telephones, the combination, with a series of finger holds,
of a make and break device, a series of electro-magnets, means for changing the
current from one to the other of said magnets, and means for limiting said changes,
substantially as set forth
6. In a calling device for telephones, the combination, with a series of finger holds,
of a make and break device, and an indicator connection with the finger holds,
substantially as set forth.
7. In a calling device for telephones, the combination, with a series of pivotally
arranged finger holds, of a stop adjacent thereto, and means for automatically
returning said finger holds to their normal position, and a make and break device,
substantially as set forth.
8. In a calling device for telephones, the combination, with a series of finger
holds, of two wheels, the rotation of one of which is limited to a pre-determined
portion of the rotation for each operation of the finger holds, and a make and
break device, substantially as set forth.
9. In a calling device for telephones, the combination, with a series of finger holds,
of two wheels means for retarding the movement of one of them in one direction, and
a make and break device, substantially as set forth. .
10. In a calling device for telephones, the combination, with a series of finger
holds, of a make and break device, two wheels, one of which is provided with means
for operating the other one and also for operating the make and break device, sub-
stantially as set forth.
11. In a calling device for telephones, the combination with a series of finger holds,
of a wheel provided with pins a make and break device, a retarding device, said pins
being adapted to operate the retarding device, and the make and break, substantially
as set forth.

page_text: 12. In a calling device for telephones, the combination, with a series of finger
holds, of a ratchet wheel and a pin wheel, a pawl on the pin wheel adapted to engage
with the ratchet wheel, means for limiting the engagement of the pawl with but one
of the ratchet teeth, irrespective of the degree of rotation of the pin wheel, of a make
and break device, and two electro-magnets, either one of which is adapted to be
placed in circuit by the rotation of the ratchet wheel, substantially as set forth.
13. In a calling device for telephones, the combination, with a series of finger
holds, of a ratchet wheel provided with pins, contact points adapted to be engaged by
said pins, a make and break device, and means for rotating the ratchet wheel by the
movement of the finger holds, substantially as set forth.
14. In a calling device for telephones, the combination, with a series of finger
holds, of a spring actuated wheel connected therewith, a ratchet wheel adapted to
be moved one step for each operation of the finger holds, a detent for holding
said ratchet wheel, a make and break device, and means for automatically releasing
the ratchet wheel by hanging up the transmitter of the telephone substantially as
set forth.
15. In a calling device for telephones, the combination, with a series of finger
holds, of a pin wheel connected therewith, a make and break device, and two
pallets, one of which is disconnected from the other when the pins are moving in
one direction but caused to engage therewith when moved by said wheel in the
opposite direction, substantially as set forth.
16. In a calling device for telephones, the combination, with a case, of a disc
journaled therein, a portion of the periphery of which is provided with finger holds,
an indicator connected with the disc, the top of the casing being cut away at one
side to form a stop, and at another point to expose a portion of the indicator, and a
make and break device substantially as set forth.
1000