Jack Improvements in the Construction of the "Spring Jacks" or Knives" and their Stoppers or Contact Plugs of Commutators for Telephonic Circuits.
Year: 1890

page_text: Date of Application, 30th Dec., 1890
Complete Specification Left, 29th Sept., 1891-Accepted, 31st Oct., 1891
PROVISIONAL SPECIFICATION.
[Communicated from abroad by SOCIÉTÉ GÉNÉRALE DES TELEPHONES (Reseaux
Telephoniques et Constructions Electriques), Manufacturers, and LOUIS
ALFRED BERTHON, Engineer, both of No. 41, Rue Caumartin, Paris,
France.]
"Jack
Improvements in the Construction of the "Spring Jacks" or
Knives" and their Stoppers or Contact Plugs of Commutators
for Telephonic Circuits.
I, CHARLES DENTON ABEL, of No. 28 Southampton Buildings, Chancery Lane,
in the County of London, Consulting Engineer and Patent Agent, do hereby
declare the nature of this invention to be as follows:-
66
This invention relates to improvements in the apparatus commonly known as
Spring Jacks or "Jack Knives" and their stoppers or contact plugs employed
in commutators for telephonic circuits whether for metallic or for simple circuits;
it consists more particularly in improved arrangements, firstly of the springs and
the double fixed outer contact for a multiple commutator with metallic circuits;
secondly, of the parts forming the stopper with two parallel contacts to the said
spring jacks" for metallic circuits; thirdly, of the spring and fixed external
contact forming the "spring jack" for multiple commutators with simple circuits;
fourthly, of the parts forming the stopper to the said "spring jack"; and fifthly,
of the same constructions of "spring jacks" and stoppers for ordinary com-
mutators with simple and metallic circuits.
66
The improvements have for their object to reduce to a minimum not hitherto
attained, the thickness of the bands of spring jacks and the dimensions of the stoppers
in all the above named applications, resulting in the following advantages.
1. The capacity of a multiple commutator, that is to say, the number of circuits
that can be connected thereto can be considerably increased.
2. If an increase of capacity is not desired, the height of a commutator con-
structed with the improved "spring jacks" and stoppers would be considerably
reduced, and thus the service of the commutator would be rendered much more
convenient.
3. The trial of the circuits, which takes place before telephonic communication
commences in order to ascertain whether the apparatus are all in proper condition,
will be effected rapidly and with great certainty, although this is effected by means
of a double contact, these being external.
According to the present invention the said spring jacks and their stoppers are
constructed as follows.
For the construction of spring jacks for a multiple commutator with metallic
circuits, a horizontal broad band of ebonite or other suitable insulating material
carried by a suitable framing has a raised edge formed along its inner side, in
which are formed a number of narrow transverse cuts situated closely side by side,
into which are introduced the springs of the spring jacks, each group of three
springs being made to correspond to one contact plug of a stopper.
These springs are held in position by a dovetail key of insulating material
passing through a longitudinal dovetail groove in the raised edge of the band,
and through corresponding dovetail notches in the upper edges of the springs.
The band has a raised edge along its outer side also, in which are formed a series
of holes, each one of which is in line with a group of three of the before mentioned
springs, and which serve to receive a tubular metal- contact piece destined to
receive one plug of the stopper, which plug fits closely therein so as to make
conducting contact.

page_text: The said external tubular contact pieces are each secured to the insulating band,
and to a metallic conducting strip on the underside thereof by means of screws
screwed through the said parts from the underside. The conducting strips are
covered with a plate of insulating material.
Each stopper carries two of the contact plugs, the ends of which are formed with
a ball shaped head, which, when the plugs are inserted into the tubular contact
piece, project beyond the latter, and are each embraced by the suitably bent ends
of two of the before mentioned springs, so as to make conducting contact therewith.
These two springs are the outer two of the before mentioned group of three, while
the third one is in the middle, and does not make contact with the plug, being
made shorter than the other two; its end is formed into a head, and when the plug
is withdrawn from between the two outer springs, these spring inwards, so as to
make contact with the middle spring, while when the plug is forced in between the
two outer ones, they are moved away so as to break contact with the middle one.
The one outer spring and the middle one are each connected by their projecting
inner ends to the terminals of one circuit, while the before-mentioned conducting
strip which is in conducting connection with the tubular conducting piece of the
plug is connected to the conducting wire which establishes the electrical com-
munications of the commutator apparatus. Thus it will be seen that when the two
plugs of the stopper are inserted into their tubular conducting pieces each one
will establish the connection of an outer circuit with the conductor of the
commutator apparatus while on withdrawing the plugs this connection is broken,
and the two wires of each circuit are coupled up by means of the middle spring.
The stopper with the two parallel contact plugs, is constructed as follows. The
two contact plugs are secured in an insulating socket formed in two halves bolted
together, and secured in an outer metal casing into the end of which the flexible
conductor carrying the two wires is suitably secured by a collar fixed thereon.
The two wires of the flexible conductor have their projecting ends bent into
spiral form, and the reduced inner ends of the conducting plugs are made to fit
within such coils so as to make contact therewith.
In applying the above construction of spring jacks and their stoppers for
multiple commutators with metallic circuits, to spring jacks and stoppers for
multiple commutators with simple circuits, the construction of the spring jacks is
precisely as above described, with the only difference that there is only one set of
three springs and a single tubular contact piece for each stopper while the latter
has only one contact plug, which is secured in the insulating socket by a pin
passing through both.
The above described construction of spring jacks and their stoppers can also be
applied to ordinary commutators with simple or metallic circuits, in which case
there is no necessity to restrict the size of the parts to the same extent as for
multiple commutators.
Dated this 30th day of December 1890.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
66
Improvements in the Construction of the "Spring Jacks" or Jack
Knives" and their Stoppers or Contact Plugs of Commutators
for Telephonic Circuits."
I, CHARLES DENTON ABEL, of No. 28 Southampton Buildings, Chancery Lane
in the County of London, Consulting Engineer and Patent Agent, 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 improvements in the apparatus commonly known as

page_text: 66
Spring Jacks" and their stoppers and contact plugs employed in commutators
for telephonic circuits whether for metallic or for simple circuits. It consists
mainly in the mode of arranging the several parts in combination relatively to
each other and their insulation, considered as a whole, that is to say:
Firstly the springs and the outer fixed double contact of which the spring jack
commutator for a multiple commutator with metallic circuits is composed, and of
the stopper with two parallel contacts for metallic circuits, which is employed in
combination with the said commutator.
Secondly, the spring and the outer fixed contact of which the spring jack
commutator is composed for multiple commutators with simple circuits, and of the
stopper with single contact for simple circuits which is used in combination with
the said commutator.
Thirdly, the same spring jacks and stoppers as those above mentioned for
ordinary commutators with metallic and simple circuits.
The improvements have for their object to reduce to a minimum not hitherto
obtained, the thickness of the bands of spring jacks and the dimensions of the stoppers
in all the above named applications, resulting in the following advantages:-
1. The capacity of a multiple commutator, that is to say, the number of circuits
that can be connected thereto, can be considerably increased.
2. If an increase of capacity is not desired, the height of a commutator
constructed with the improved spring jacks and stoppers would be considerably
reduced, and thus the service of the commutator would be rendered much more
convenient.
3. The trial of the circuits (that is to say the operation which consists, before
establishing any communication with a spring jack, in insuring that there is not
already established a communication by means of the corresponding spring jack in
another section of the multiple commutator) will be effected rapidly and with
certainty, although this is effected with the aid of a double contact, as the two
contacts are external.
This invention is illustrated by the following figures on the accompanying
drawing:
Fig. 1 is a vertical section of a band of spring jacks for a multiple commutator
with metallic circuits, shewing the general arrangement, juxta position and insu-
lation of the springs and of the fixed external double contact.
Fig. 2 shews a horizontal section of the same band, shewing two adjacent spring
jacks.
Figs. 3 and 4 shew a modification of the band.
Figs. 5 and 6 shew respectively a sectional plan and a longitudinal section of
the stopper with two parallel contacts.
Fig. 7 shews a cross section on line x x and
Fig. 8 shews a side view of the stopper with two contacts.
Figs. 9 and 10 shew respectively a vertical section and a horizontal section of a
band of spring jacks for a multiple commutator with simple circuits, shewing that
with a stopper having a single contact, as shewn at Figs. 11, 12 and 13, the mode
of arranging the springs and fixed contact relatively to each other, and their
insulation, considered as a whole, as above referred to, is applicable to a multiple
commutator with simple circuits. In this case each band will include double the
number of spring jacks as compared with those contained in a band of the same
length for a multiple commutator with metallic circuits.
Figs. 14 and 15 shew respectively a horizontal section and a part front view of
a modification of the band of spring jacks for a multiple commutator operating
with a stopper shewn separately at Figs. 18 and 19.
Fig. 16 shews a section on line and
Fig. 17 a section on line z .
Y y
Referring to Figs. 1 and 2 which shew a vertical and horizontal section of a
band of spring jacks for a multiple commutator with metallic circuits, the following

page_text: is the mode of construction and the functions of the various parts composing
the same.
a is a band of ebonite or other similar insulating material, which is grooved for
the reception of the key f of ebonite or other similar insulating material and which
has transverse grooves for receiving the outer fixed contacts bb'. . . . on the one
side, and the springs
on the other side.
The outer fixed contacts b b¹
are composed of rectangular blocks of brass,
bronze or other suitable metal having a cylindrical hole through them of a size
corresponding to the diameter of the cylindrical parallel contact pieces c c¹ of the
stopper F. These contacts are made to fit tightly in their grooves, and are
in addition fixed on the underside by means of a screw » to a hardened copper
plated to the projecting end of which is fixed the wire which forms part of the.
general electrical communications of the commutator.
Two of the springs correspond to each of the contacts c c¹ of the stopper, as
also a spring situated between them, which performs the office of fixed contact;
these springs are of hardened copper, and have formed at their inner part either
by cutting with a notch or recess, by preference of dovetail shape corresponding
to the cross section of the key, so that the latter in. being slid into its groove in
the plate a at the same time locks the springs in position on the band. To one
of the springs and to the contact spring are fixed the wire conductors for
the general electrical communications of the commutator.
For preventing the plates d fixed by the screws and rivets v¹ from making
contacts with the metal parts of the band of spring jacks situated below, in the
case where a number of rows of spring jacks arranged one above the other are
employed, the under surface of the plates d are insulated by a sheet of ebonite g
having holes at the points where the screws and rivets are situated.
The stopper with two parallel contact plugs used in combination with the above
described spring jack commutator consists of two contact pieces of brass, iron, or
steel imbedded with their ends in a socket of ebonite or other suitable insulating
material formed in two halves, of the form shewn at Figs. 5, 6 and 7.
These two contacts c c are formed at their outer end with a spherical head,
while the inner end is formed into a pin h h serving to make contact with the
helical wires forming the two conductors of a flexible cable serving to establish
the communications; at the point where the two helices of the cable are united
under the same sheathing is fixed a ring which is contracted at the middle so as
to make it assume the form of the figure eight, and thus be securely fixed on the
cable. A second ring which is fixed by a screw to the tube of thin brass which
forms the covering of the stopper, has for its object to secure the cord effectually
to the stopper by abutting against the piece k.
C
The two contact plugs c c are fixed in the stopper by means of a screw m which
passes right through the thickness of the stopper.
The copper casing of the stopper is slotted on both sides to the extent n necessary
for preventing all contact between such casing and the before described parallel
contact blocks b b' of the commutator.
The above description of the spring jack commutator and of the stopper for a
multiple commutator with metallic circuits, is equally applicable to the spring jack
commutator and stopper for multiple commutator with simple circuits such as is
shewn at Figs. 9, 10, 11, 12 and 13, by simply dividing each group of blades
forming a spring jack into two, the stopper being made with a single contact plug
as shewn at Figs. 11, 12 and 13 combined as already described with reference to
the stopper with two parallel contact plugs.
Figs. 14 to 17 shew a modification of the band of spring jacks. Each band is
formed of two parts a and a¹; these two parts are mounted on the framing so as
to be rigidly fixed in relation to each other, the connection being effected upon
iron uprights M of the commutator framing.
This division into two parts has for its object to render each band independently

page_text: adjustable so that the devices of a band can be easily changed according to
requirements.
Each spring jack of a subscriber consists of two square sockets b b' into which
enter the springs cc' of the stopper (shewn separately at Figs. 18 and 19) for
effecting the communication. These springs c c push against the two pistons g g
of square section, each of which when at rest, that is to say, when the stopper is
withdrawn, is kept in a forward position towards the band a by the springs S S¹,
being guided both by the sockets a a¹ of the same section as the sockets bb',
which slide rods formed in one with the pistons, and by the insulating material
forming the band a¹.
in
The principle of action being the same as described above, the arrangement will
be readily understood from the Figs. 14 to 17 without further description.
The stopper for these spring jacks is shewn at Figs. 18 and 19. The conducting
rods cc instead of being cylindrical are formed as spring blades, one of which in
each rod is formed with a bulge at the end. This bulge has for its purpose to
prevent the stopper, when introduced into the spring jack, from being forced back
by the opposite pressure of the springs S S¹ Fig. 14.
The springs c c¹ are fixed on brass stems o o' imbedded in insulating material.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A band of spring jacks for commutators consisting of an ebonite band with
two raised borders one of which receives the fixed external contacts b b¹, two to
each commutator, and formed of small blocks having a cylindrical hole through
them, while the other raised border has slots in which are fixed by means of a
longitudinal key f, three springs for each commutator consisting of two side
springs and a fixed spring / situated between the other two, the ebonite band
being furthermore provided with plates on its under side and projecting on the
opposite side to the sockets bb, one plate being below each such socket, to which
it is connected by a screw v, the electrical connections being established for each
commutator between two plates d d, two of the four flexible contact springs rr³,
and two fixed contact springs ll', substantially as described.
2. The use in combination with the commutator referred to in the preceding
claim, of a stopper composed of two parallel contact plugs e c¹ having ball shaped
ends for enabling them to be seized by the bent ends of the side springs of
the commutator, while the other ends of the plugs c c have pins h² formed thereon
for making effectual contact with the helically wound ends of the wires of the
flexible conductor i, the plugs being imbedded between the halves of a divided
ebonite socket which is enclosed in a metal casing that also serves, by means of
a ring, to secure a ferrule k which is clamped upon the flexible conductor just
behind the pins of the plugs c c', substantially as described.
3. The combination of parts constituting a band of spring jacks for a multiple
commutator with metallic circuits, as herein described with reference to Figs. 1
and 2 of the drawings.
4. The modified form of band described with reference to Figs. 3 and 4.
5. The stopper with two parallel contacts described and shewn at Figs. 5 to 8
of the drawings for use with the band of spring jacks referred to in the preceding
claims.
6. The combination of parts constituting a band of spring jacks for a multiple
commutator with simple circuits, described with reference to Figs. 9 and 10, for
operating in combination with a stopper with single contact such as described with
reference to Figs. 11, 12 and 13 of the drawings.
7. The band of spring jacks for a multiple commutator formed of two parts,
secured to the framing and carrying two square sockets bb' into which pass the
springs c c of the stopper, which springs are made to push back two guided spring
pistons, arranged as described with reference to Figs. 14 to 17 of the drawings.

page_text: 8. The stopper for the band of spring jacks referred to in the preceding claim,
the rods or plugs of which are formed of spring blades, one of which has a bulge,
and which are fixed on .brass rods imbedded in an insulating block, as described
with reference to Figs. 18 and 19 of the drawings.
Dated this 29th day of September 1891.
ABEL & IMKA1,
Agents for the Applicant.