Improvements in Calling-off Apparatus for Telephone Exchanges.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Calling-off Apparatus for Telephone Exchanges.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate, Westminster,
in the County of London, Electrical Engineers, do hereby declare the nature of
this invention (which has been communicated to us from abroad by Siemens and
Halske, of 94 Markgrafenstrasse, Berlin, in the German Empire, Electrical
Engineers) to be as follows:-
This invention relates to improved calling-off apparatus for central telephone
exchanges so arranged that the subscribers shall be able to give a simple visible
sign on calling-off, which sign shall not be affected by repeated calling-on..
A polarised calling-off indicator drop which is only actuated by a continuous
current is worked either by turning to the left the handle of the magneto
generator at the subscriber's station, or by an automatic device to be presently
described.
The arrangement of the connections will be understood on reference to the
diagram at Figure 5 of the accompanying drawing, in which for clearness sake
the speaking circuits are omitted.
V₁ and V represent an associated pair of pegs. U is a switch which is made by
the weight of the peg V₁ to connect up the battery B. K is the above mentioned
polarised calling-off indicator, with the electro-magnet coils E, and E. The
latter are connected to a point between the two pegs and to earth.
The action of the arrangement will be seen on following the operations after a
connection has been established between two subscribers.
If the connection between two subscribers X and Y has been established at the
exchange, the pegs V1 V2 have been inserted in the corresponding jacks, and
the switch U has broken the connection with the battery. If now calls the
subscriber Y by turning to the right his magneto-generator which is put to earth,
the current will pass through the line to the pegs V and V and to the subscriber Y.
One part of the current will pass through the calling-off indicator K, without
actuating this, as in consequence of its being polarised, it will not respond to the
particular current sent; if after completing the conversation, the subscriber X
or Y calls off, this must be effected by turning the crank of the magneto-generator
to the left hand. The current will then pass on the one hand from the magneto-
generator through the line, the pegs V and V2, to the other subscriber and on the
other hand it will pass to the calling-off indicator. With the current passing in
this direction the calling-off indicator will be made to drop and the exchange
operator will thus be informed that the conversation is ended, whereupon he will
remove the connecting pegs.
It has already been stated that the calling-off of the subscriber can be effected

page_text: either by turning the magneto-generator crank to the left by hand, or
automatically.
An arrangement for effecting this automatically is shewn at Figures 1 to 3
of the drawings
If the crank K is turned to the right for calling on, the ratchet wheel is 5
turned to the left by means of the transmitting gearr, of which is fixed on
the same spindle as 3. H' is a two-armed lever having a fixed pivot at a, and
whose one arm is drawn downwards by a strong spring f, so that the other arm
has the tendency to rise, its motion being limited by the stop s¹.
1
On this arm of the lever H¹ is pivotted the pawl k, which is acted upon by the 1
spring so as to engage with the ratchet wheel 3, and is prevented by the stop s
from being pressed too far down. By the rotation of the ratchet wheel to
the left the pawl k and its end of the lever H' is depressed, and consequently the
other end thereof is raised, so that the beak y of the lever H (which is pivotted
at a² and is acted upon by the spring f) can project underneath the end of H.
If the
The stop prevents the lever H³ from moving too far to the right.
telephone receiver be hung on the hook of lever H³, the pallet S¹ thereon
will pass behind the pallet S of lever H2, and this will thereby be moved
sufficiently to the left to cause beak y to release the end of lever H³, so that
the latter can follow the downward pull of the spring, when the pawl k, acting 2
in an upward direction will turn the ratchet wheel to the right, such turning
to the right of effects a turning to the left of the magneto-generator crank K
and consequently there will be produced a reverse current that will effect an
automatic calling-off.
When the river is lifted off II, the pallet S will be situated below the
pallet S2; lever H³ will bear against the stop S3, and the device can be
put in action for calling by turning the crank K to the right.
y
above .r.
If the receiver is hung on H³ so that S¹ is above $2 as before described, the crank
can nevertheless be turned to the right so as to bring the beak
When
this has been done, the receiver can be lifted from its hook without causing a
calling off. As the pallet S1 will slide past S the lever H can only be pressed
slightly to the right, and will not effect any disengagement of y and r.
Figure 4 shews another arrangement for automatic calling off. By turning the
magneto generator crank K to the right, the spring drum T (which is loose on a
fixed axis but is connected thereto by the spiral spring E) will be turned to the
left through the agency of the toothed wheel and toothed segment on the
drum; to the latter is also fixed the ratchet wheel ³, against the sides of which
bear with friction two springs f8, so as to tend to follow its motion. These
On the drum
springs are fixed rigidly to the two-ended lever H pivotted at a.
and ratchet wheel being turned to the left by the rotation to the right of the crank
handle, the spiral spring I will be wound up to a certain extent; at the same time,
the springs in following the rotation, will turn lever H so as to cause pawl k¹
acted upon by spring f¹ to engage with the ratchet wheel r³.
The rotation of the drum and ratchet wheel will continue until the last tooth A
of the segment arrives at the pinion r¹, when any farther winding up of the
spring will cease notwithstanding the continued rotation of the pinion. Un ceas-
ing the rotation of the magneto-generator crank, the pawl will continue to hold
the drum and ratchet wheel in the described position with the spring F wound up,
until by the hanging of the telephone receiver on the hook H³ the tail of the latter
will be moved upward against the pull of spring f³, and the blade spring f³ on
such tail, in pressing upward the tail of H will disengage the pawl from the
ratchet wheel whereupon this and the drum T will be free to follow the pull
of the spring F in rotation to the right, and will consequently effect the rotation
of the crank handle K to the left, so that, as above described a reversed current
will be produced for actuating the calling-off indicator drop.
If the receiver is hanging on its hook, the thin spring f5 of the latter will be
situated above the lever H, and on removing the receiver the spring f in moving

page_text: downward with H³ will yield sufficiently to pass H*. If on the other hand the
receiver is off the hook, the spring f³ will be below the lever H4, and consequently
it does not interfere with the above described action of winding up the spring.
Dated this 10th day of March 1897.
ABEL & IMRAY,
Agents for the Applicants.
Improvements in Calling-off Apparatus for Telephone Exchanges.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate, Westminster,
in the County of London, Electrical Engineers, do hereby declare the nature of
this invention (which has been communicated to us from abroad by Siemens &
Halske, of 94 Markgrafenstrasse, Berlin, in the Empire of Germany, Electrical
Engineers) 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 improved calling-off apparatus for central telephone
exchanges so arranged that the subscribers shall be able to give a simple visible
sign on calling off, which sign shall not be effected by repeated calling-on.
A polarised calling-off indicator drop which is only actuated by a continuous
current is worked either by turning to the left the handle of the magneto
generator at the subscriber's station, or by an automatic device to be presently
described.
The arrangement of the connections will be understood on reference to the
diagram at Figure 5 of the drawing accompanying our provisional specification in
which for clearness sake the speaking circuits are omitted.
V₁ and V represent an associated pair of pegs. U is a switch which is made by
the weight of the peg V1 to connect up the battery B. K is the above mentioned
polarised calling-off indicator, with the electro-magnet coils E₁ and E. The
latter are connected to a point between the two pegs and to earth.
The action of the arrangement will be seen on following the operations after a
connection has been established between two subscribers.
If the connection between the subscribers X and Y, has been established at the
exchange, the pegs V1 V have been inserted in the corresponding jacks, and
the switch U has broken the connection with the battery. If now I calls the
subscriber Y by turning to the right his magneto-generator which is put to earth,
the current will pass through the line to the pegs V and Vs and to the subscriber Y.
One part of the current will pass through the calling-off indicator K, without
actuating this, as in consequence of its being polarised, it will not respond to the
particular current sent; if after completing the conversation, the subscriber X
or Y calls off, this must be effected by turning the crank of the magneto-generator
to the left hand. The current will then pass on the one hand from the magneto-
generator through the line, the pegs V₁ and V2, to the other subscriber, and on the
other hand, it will pass to the calling-off indicator. With the current passing in
this direction the calling-off indicator will be made to drop and the exchange
operator will thus be informed that the conversation is ended, whereupon he will
remove the connecting pegs.
It has already been stated that the calling-off of the subscriber can be effected
either by turning the magneto-generator crank to the left by hand, or
automatically.
An arrangement for effecting this automatically is shewn at Figures 1 to 3 of
the drawings accompanying our provisional specification.

page_text: If the crank K is turned to the right for calling on, the ratchet wheel ³ is
turned to the left by means of the transmitting gear, of which is fixed on
the same spindle as 3. H¹ is a two-armed lever having a fixed pivot at a, and
whose one arm is drawn downwards by a strong spring f, so that the other arm
has the tendency to rise, its motion being limited by the stop st.
2
On this arm of the lever H is pivotted the pawl k, which is acted upon by the
spring so as to engage with the ratchet wheel ³, and is prevented by the stop s
from being pressed too far down. By the rotation of the ratchet wheel to
the left the pawl k and its end of the lever H is depressed, and consequently the
other end thereof is raised, so that the beak y of the lever H (which is pivotted
at a² and is acted upon by the spring f) can project underneath the end of H.
The stop prevents the lever H from moving too far to the right. If the
telephone receiver be hung on the hook of lever H³, as at Figure 3, the pallet S¹ there-
on will pass behind the pallet S of lever H³, and this will thereby be moved.
sufficiently to the left to cause beak y to release the end of lever H', so that
the latter can follow the downward pull of the spring f, when the pawl k, acting
in an upward direction will turn the ratchet wheel to the right, such turning
to the right of effects a turning to the left of the magneto-generator crank K
and consequently there will be produced a reverse current that will effect an
automatic calling-off.
When the receiver is lifted off H3, the pallet S will be situated below the
pallet S as at Figure 1; lever He will bear against the stop 8%, and, the device can be
put in action for calling by turning the crank K to the right.
y
If the receiver is hung on H³ so that S is above as before described, the crank
can nevertheless be turned to the righi so as to bring the brak
above. When
this has been done, the receiver can be lifted from its hook without causing a
calling off. As the pallet S¹ will slide past the lever H can only be pressed
slightly to the right, and will not effect any disengagement of y and r.
Figure 4 shews another arrangement for automatic calling off. By turning the
magneto-generator crank K to the right, the spring drum T (which is loose on a
fixed axis but is connected thereto by the spiral spring F) will be turned to the
left through the agency of the toothed wheel and toothed segment on the
drum; to the latter is also fixed the ratchet wheel, against the sides of which
These
bear with friction two springs fo, so as to tend to follow its motion.
On the drum
springs are fixed rigidly to the two-ended lever H pivotted at a.
and ratchet wheel being turned to the left by the rotation to the right of the crank
handle, the spiral spring F will be wound up to a certain extent; at the same time,
the spring fin following the rotation, will turn lever H so as to cause pawl k¹
acted upon by spring f¹ to engage with the ratchet wheel ³.
The rotation of the drum and ratchet wheel will continue until the last tooth A
of the segment arrives at the pinion r¹, when any farther winding up of the
spring will cease notwithstanding the continued rotation of the pinion. În ceas-
ing the rotation of the magneto-generator crank, the pawl ¹ will continue to hold
the drum and ratchet wheel in the described position with the spring I wound up,
until by the hanging of the telephone receiver on the hook H³ the tail of the latter
will be moved upward against the pull of spring f³, and the blade spring fo on
such tail, in pressing upward the tail of H will disengage the pawl ¹ from the
ratchet wheel whereupon this and the drum T will be free to follow the pull
of the spring F in rotation to the right, and will consequently effect the rotation
of the crank handle K to the left, so that, as above described a reversed current
will be produced for actuating the calling-off indicator drop.
If the receiver is hanging on its hook, the thin spring f of the latter will be
situated above the lever H, and on removing the receiver the spring in moving
downward with H³ will yield sufficiently to pass H. If on the other hand the
receiver is off the hook, the spring fo will be below the lever H, and consequently
it does not interfere with the above described action of winding up the spring.

page_text: Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:-
-
1. In calling-off apparatus for telephone exchanges, the interposition in the
branch of the circuit of two communicating subscribers, of a polarised calling-off
indicator drop, so that the indicator drop is only actuated when calling-off (with
rotation of generator to the left hand) and is not actuated by a repeated calling-on
(rotation to the right) substantially as described.
2. In calling-off apparatus arranged as set forth in the first claim, the arrange-
ment whereby, on operating the indicator for calling, a device is operated which
effects the storing up a certain amount of mechanical energy, and is then locked,
the device being liberated so as to automatically operate the indicator for calling-
off, on hanging the receiver on its hook lever, which is thereby made to withdraw
the catch that locks the said device substantially as described.
3. In calling-off apparatus such as is referred to in the second claim, the com-
bination with the magneto-inductor of a ratchet wheel r operating a lever H with
pawl k, so as to strain a spring f, the lever being held in the strained position by
a catch Hy S, that is withdrawn by the hook lever H³ S¹ on hanging on the
receiver, substantially as described with reference to Figures 1, 2 and 3 of the
drawings.
4. In calling-off apparatus such as is referred to in the second claim, the com-
bination with the magneto-inductor of a spring barrel T geared thereto so that the
spring of the barrel is wound up on turning the inductor for calling, the barrel
being then locked by a catch H, which is brought into engagement by the action
of frictional spring levers fo, and is afterwards disengaged by the spring tail f³
of the hook-lever H³ on hanging on the receiver, substantially as described with
reference to Figures 4 and 5 of the drawings.
Toted 10th dose of Damuhan
1007