Improvements in Springjacks for Telephone Switchboards.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Springjacks for Telephone Switchboards.
I, JOHN EDWARD KINGSBURY, of 79, Coleman Street, in the City of London,
Manager, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by The Western Electric Company, of Chicago,
Illinois, United States of America,) to be as follows:-
This invention concerns terminal springjacks or sockets for telephone lines
in telephone switch-boards; the invention consisting in certain details of con-
struction and disposition of parts for attaining compactness of arrangement and
cheapness of construction, and for affording secure contact between the terminal
pieces in the springjack and corresponding portions of the plug.
My improvement applies to springjacks mounted in groups on common bases
or supporting plates, such as are usually known as strips of springjacks. In
constructing the springjack I provide a strip or plate of insulating material
through which I drill transverse openings to receive the metal contact pieces of
the springjacks. One of these contact pieces consists in a short tubular thimble
closely fitting the transverse opening and placed therein near one edge of the
strip, its orifice being preferably accessible near the front of the strip for testing
purposes; from this contact piece an extension is led to the rear of the strip of
springjacks through a suitably inclined duct between adjacent perforations.
Another of the contact pieces of the jack consists in a nearly annular spring
located in the perforation at the rear of the thimble before described, adapted to
encircle and grasp the inserted plug; a metallic extension from this contact
piece also being led to the rear of the strip of springjacks. The third contact
portion is a flat spring lying axially in the transverse perforation and tightly
fitted therein at its rear extremity, the free extremity of the spring being in
position in the transverse opening to register with the tip of a plug inserted in
the jack. The three contact portions of each springjack are thus located in a
single drilled perforation in the strip with their axes nearly concentric, and two
ducts are provided for leading the terminals of two of the contact pieces to the
rear of the strip; so that the operations essential in forming the strip of insulating
material to receive the metallic parts of each jack, which operations ordinarily
constitute the most costly processes in the construction of the springjack, consist
merely in drilling the transverse opening and in forming two ducts extending
therefrom for each springjack, together with a narrow slit opening into the per-
foration. One of the ducts may be a narrow channel cut by means of a saw; but
with these exceptions the operations of forming the insulating base plate consist
in drilling openings, the expensive processes of milling and drifting openings being
wholly avoided.
Similar methods of construction may be employed for other electrical circuits,
for example, an additional spring may be introduced for the line and provision
made for the crossing of the nearly circular contact and the thimble by the plug
so as to enable a 2-way cord to be used instead of a 3-way.
Dated this 26th day of July 1897

page_text: Improvements in Springjacks for Telephone Switchboards.
I, JOHN EDWARD KINGSBURY, of 79, Coleman Street, in the City of London,
Manager, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by The Western Electric Company, of Chicago,
Illinois, United States of America) and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following state-
ment:
This invention concerns terminal springjacks or sockets for telephone lines
in telephone switch-boards, the invention consisting in certain details of con-
struction and disposition of parts for attaining compactness of arrangement and
cheapness of construction, and for affording secure contact between the terminal
pieces in the springjack and corresponding portions of the plug.
My improvement applies to springjacks mounted in group on common bases
or supporting plates, such as are usually known as strips of springjacks. In
constructing the springjack I provide a strip or plate of insulating material
through which I drill transverse openings to receive the metal contact pieces of
the springjacks. One of these contact pieces consists in a short tubular thimble
closely fitting the transverse opening and placed therein near one edge of the
strip, its orifice being preferably accessible near the front of the strip for testing
purposes from this contact piece an extension is led to the rear of the strip of
springjacks through a suitably inclined duct between adjacent perforations.
Another of the contact pieces of the jack consists in a nearly annular spring
located in the perforation at the rear of the thimble before described, adapted to
encircle and grasp the inserted plug; a metallic extension from this contact
piece also being led to the rear of the strip of springjacks. The third contact
portion is a flat spring lying axially in the transverse perforation and tightly
fitted therein at its rear extremity, the free extremity of the spring being in
position in the transverse opening to register with the tip of a plug inserted in
the jack. The three contact portions of each springjack are thus located in a
single drilled perforation in the strip with their axes nearly concentric, and two
ducts are provided for leading the terminals of two of the contact pieces to the
rear of the strip; so that the operations essential in forming the strip of insulating
material to receive the metallic parts of each jack, which operations ordinarily
constitute the most costly processes in the construction of the springjack, consist
merely in drilling the transverse opening and in forming two ducts extending
therefrom for each springjack, together with a narrow slit opening into the per-
foration. One of the ducts may be a narrow channel cut by means of a saw; but
with these exceptions the operations of forming the insulating base plate consist
in drilling openings, the expensive processes of milling and drifting openings being
wholly avoided.
Similar methods of construction may be employed for other electrical circuits,
for example, an additional spring may be introduced for the line and provision
made for the crossing of the nearly circular contact and the thimble by the plug
so as to enable a 2-way cord to be used instead of a 3-way.
Figure is a full sized plan of a strip of ten springjacks and Figure 2 is an
underside view. Figures 3 and 4 are part rear and front elevations three times
full size. Figure 5 is a section the upper or rear part being on the line 5-5
Figure 3 and lower or front part being on the line 5-5 Figure 4. Figure 6 is
a section on the line 6-6 Figure 5.
The strip or base plate a may be of hard rubber or other similar insulating

page_text: material. For each springjack an opening a¹ is drilled deeply into the strip from
the front edge; this opening meets a second perforation a² of smaller diameter,
drilled from the rear of the strip, the axes of these tubular openings being so dis-
posed with relation to each other that their walls lie in the same straight line at
one point. From the forward extremity of the opening a¹ a duct a³ of small
diameter is drilled obliquely downward and outward toward the rear and under
surface of the strip meeting a similar duct a parallel to the perforations a¹ a²
and leading to the rear of the strip. A section of this duct is seen in Figure 6,
while a rear view of the same appears in Figure 3. A duct a is drilled obliquely
upwards and rearwardly from the shoulder at the junction of the openings a
and a. Further, slots or saw cuts a are formed in the rear of both the upper
and lower faces of the strip on the centre line of each opening a³ with a small
lateral extension or recess a² on each surface of the strip. Similar but longer
slots or saw cuts a8 are formed in the under side of the strip into the ducts a¹.
The metal parts comprised in a single springjack for assembly in these openings
are shown in Figures 7 to 12; a thimble 6 Figures 7 and 8 having a rearwardly
projecting narrow extension 6' formed integral with it, the length being somewhat
greater than the breadth of the strip; a nearly tubular thimble c, Figures 9 and 10
preferably of stiff and resilient metal, having also a lateral terminal piece c¹
formed from the same piece, and a flat spring d Figures 11 and 12, having a
broadened bushing & formed with a lug . The thimble c is not quite tubular
in form, the narrow lip of the thimble being bent inward to give the tube a some-
what spiral section as shown in Figure 6. The stem c¹ thereof is narrowed
throughout a portion of its length, so that a shoulder c is formed upon it. The
flat spring has the usual crimped or curved extremity designed to conform to
the spherical tip of the plug and to engage it in such manner as to retain the
plug in place in the springjack.
In assembling the springjack the flat spring d is inserted in the opening a².
the broad portion entering the slots a on each side of the strip; the lugs d
are in the plane of the spring, when this is put in place, but are subsequently bent
over to enter the recesses a extending laterally from the slots a. Hence when
the spring is in place its transverse movement is prevented by the engagement
of the broad portion with the walls of the slot a, while it is secured against
longitudinal movement by the lugs engaging the recesses a.
The thimble c is placed within the strip from the front thereof, the stem or
extension threading duct a³ until the shoulder comes against the floor of the
tubular opening a¹ at its junction with a²; the thimble is secured in this position
by a pine passing through the wall of the socket and riveted in the thimble c.
The thimble is inserted in the opening a with its outer edge flush with the strip
of springjacks so as to be accessible for the usual operation of testing; the
extension from the thimble being threaded through the ducts a3 a4 and thence
through the saw-cut a³ to the rear of the springjack, and being secured in the
duct by twisting the broadened terminal through a right angle so that it cannot
be withdrawn from the duct. This thimble also should preferably be secured in
place by means of a pin f through the hard rubber.
The plug (Figure 13) designed for use with this springjack comprises the usual
spherical tip g, and two concentric metallic sleeves al and g³. The length of the
sleeve should be such that when the plug fully inserted in the spring jack
the sleeve will extend through or slightly beyond the inner end of the thimble . The
sleeve gl is of proper length and in suitable position to enter the spring thimble e,
and is of such diameter as to be grasped with force thereby. The tip g is
obviously designed to be thrust under the curved extremity of spring d and to be
engaged thereby.
From the foregoing description it will be apparent to one familar with spring-
jacks for telephone switchboards as usually constructed that the present spring-
jack is much more simple and compact than any heretofore produced, while the
operations involved in forming and assembling the parts are of the simplest nature,

page_text: It will be further apparent that the electrical connection formed between the
spring d and the tip g, the thimble c and the sleeve g', and the thimble and the
sleeve g², respectively, will be firm and reliable, inasmuch as the first two contacts
are formed between rigid bodies and springs, while the last is fornied between a
thimble and the sleeve forced against it by the pressure of the springs.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I
claim is:
1. In a springjack the combination with a supporting plate and a tubular open-
ing therein, of an open ring of spiral section in the said tubular opening, sub-
stantially as described.
2. The combination with a supporting plate having a tubular opening formed
therein, of a tubular contact piece of spiral section, and a plug adapted to enter
the said tubular contact piece, substantially as described.
3. In a springjack the combination with a supporting base having a transverse
tubular opening therein, of a contact ring in the forward extremity of said opening,
and a flat spring mounted in a nearly axial position in said tubular opening having
its extremity presented before the opening in the said ring to engage the tip of a
plug therein, as described.
4. In a springjack, the combination with a base of insulating material having a
tubular opening formed therein, of a contact thimble secured in the forward
extremity of said opening, a second contact ring of spiral section at the rear of
said thimble, and a flat spring secured in a substantially axial position in the said
opening having its extremity presented before the opening of the spiral ring, and
a plug in the springjack having three cylindrical contact pieces registering with
the thimble, the ring, and the flat spring, respectively, as described.
5. In a springjack; the combination with a plate of insulating material having
a transverse tubular opening therein, the forward portion of said opening being of
greater diameter than the rear, of a thimble in the larger opening and a flat spring
lying in the axis of the perforation secured in the constricted portion of said
perforation, and a terminal extension of the said thimble passing through a duct
parallel with said constricted portion and opening into the larger portion, sub-
stantially as described.
6. Springjacks substantially as described and shown in the drawings.