Improvements in the Construction of Spring-jacks used in Telephonic Switch-boards.
Year: 1896

page_text: PROVISIONAL SE
IFICATION.
Improvements in the Construction of Spring-jacks used in
Telephonic Switch-boards.
We, DANIEL SINCLAIR and WILLIAM AITKEN, both of Oxford Court, Cannon
Street, in the City of London, Engineers, do hereby declare the nature of this
invention to be as follows:-
This invention has for its object improvements in the method of construction
of spring-jacks, or switches for use in connexion with telephonic or telegraphic
switch-boards, and making such spring-jacks simpler and stronger than
heretofore.
The construction may be described as follows;
The strip of spring-jacks, or switches, is made up of two parallel pieces of
vulcanite, as is commonly the case, the front piece containing the barrels, or bush
connexions, into which the plugs are to be inserted; the back piece carrying
the springs and other connexions forming the switch, and the novelty of our
invention consists in the method of constructing and fixing, as hereinafter
described.
The back piece consists of a strip of vulcanite, of suitable length. This back-
piece may be 1" more or less, from back to front, and 3", or any other desirable
thickness.
The following is a description of a strip of spring-jacks, constructed accord-
ing to our invention, and of a size in common use, viz., 11 by "face
measurement.
The back piece is perforated from back to front by, say, 20 rectangular holes,
each "in the thickness by 3" in the length of the strip; this leaves a partition
of 1/8th in. solid vulcanite between the holes, and 1/8th in. solid vulcanite above
and below the holes. The rectangular holes may, under certain conditions, be
formed at right angles to the position herein described.
The springs have the front part free to move as is usual; the fixed part is cut
down to ", (the height of the hole before mentioned) for a distance equal to the
exact width of the vulcanite (about 1"); this leaves a shoulder at top and bottom,
and back and front on the springs. The back part of the spring is finished with
a soldering tab, in the usual well-known manner. The springs and connexions
required for a switch or spring-jack are laid together in their respective positions,
and the ends passed through the hole before-mentioned, the width of the springs
passing through the 3" width of the holes, i.e., at right angles to their ultimate
position.
The springs and connexions have now to be turned on edge, and it will be
found that as the springs are free to move on each other this can easily be done,

page_text: and the shoulders on the springs, coming against the vulcanite, prevent any;
movement in the line of the springs.
Spacing-pieces, or wedges, of vulcanite or other suitable material, are now forced
between the springs, to keep them rigidly in their proper positions. This will
usually be found sufficient, but these spring-jacks, or switches, may be made with
a raised surface, or pin, on the spring, at the fixed part, which will ride into a
hollow in the vulcanite spacing-piece, or wedge, the centre vulcanite being pro-
longed forward between the two inner springs, and having a hole for the raised
surface, or pin, on the spring, to ride into; the spring being flexible, can be held.
or forced aside, while the vulcanito wedge is being inserted. This wedge acts
as a key to keep the whole immoveable.
From the foregoing, it will be seen that our invention renders unnecessary the
use of screws, with their attendant colletted springs, for fixing and building up,
and also does away with the use of adhesive materials for keeping the springs in
position.
Although we preferably construct our spring-jacks, or switches, on the principle
above described, viz., with parallel strips, one carrying the springs, and the other
the bushes, our invention may be applied to most of the well-known patterns of
spring-jacks.
Our invention admits of modification in construction which would readily
suggest themselves to those skilled in the art, and we, therefore, do not limit our-
selves to the precise details of construction, described herein.
Dated this 27th day of November 1896.
WILLIAM AITKEN.
DANIEL SINCLAIR.
Improvements in the Construction of Spring-jacks used in
Telephonic Switch-boards.
We, DANIEL SINCLAIR and WILLIAM AITKEN both of Oxford Court, Cannon
Street, in the City of London, Engineers, 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:-
Our invention has for its object the improvement in the method of construction
of spring-jacks or switches for use in connection with telephonic or telegraphic
switch boards, and the making of such spring-jacks simpler and stronger than
heretofore. In a strip of spring jacks or switches constructed in accordance with
our invention, the springs and bush or barrel connections necessary to make up a
strip of spring jacks, are mounted in two parallel pieces of vulcanite or other
suitable insulating material, as is commonly the case, the front piece containing
the barrel or bush connections and the back picce the springs and other con-
nections, which together form the spring jacks or switches, and the novelty of
our invention consists in the method of constructing and fixing the springs and
connections into the back piece, as hereinafter described.
In the accompanying drawings, illustrating our invention
Fig. 1 Is a plan view of a strip of 7 point spring jacks constructed according
to our invention.
Fig. 2. A section of the same on the line C. D.
Fig 3. The front elevation of the front niece

page_text: Fig. 4. The section through the line A. B. showing the back strip.
Fig. 5. An enlarged view showing a method of locking the spacing pieces of
the jack or switch.
Fig. 6. Is a plan view of a part of a strip of 5 point branching spring-jack,
constructed according to our invention.
Fig. 7. Is a section of the same on the line E. F.
Fig. 8. The front elevation of the front piece and
Fig. 9. A section of the spring jack on the line G. H. showing the back piece.
We will now proceed to explain the various parts of these drawings by letters
of reference, similar portions in the various figures being similarly lettered.
a is a piece of vulcanite, or other suitable insulating material forming the front
of a strip of spring jacks, carrying the bush or barrel connections, 1.
bis the back piece, perforated from back to front by rectangular holes m, for
the reception of the springs and connections n, n¹, n³, n³, n, and the spacing-
pieces o, o, o 03, 61, are rectangular ridges on the back piece b, the object being
to transfer the strain from the weakest part of the springs, n, n', n², n², n².
c is a metal pillar or tube for spacing and holding rigidly in position the back
and front pieces a and b by means of the screws and .
e are projections formed on the springs n, n', n, n³, by stamping or otherwise,
which serve when in conjunction with suitable indentation on the spacing
pieces o, 0, 0, 0, to securely lock the various portions in their respective positions.
We will now proceed to describe the construction of a strip of 7 point spring
jacks in accordance with our invention.
The front piece a is constructed as shown on drawing, and in the well known
manner, and the back piece b is perforated from back to front with rectangular
holes m separated from each other by the rectangular ridge b of vulcanite, as
shown in plan on Fig. 1, the thickness of such ridge being preferably equal to
the thickness of the material above and below the rectangular hole.
The springs n, n', &c. have the front part free to move, as is usual, the fixed
portion of the springs, however, according to our invention, is reduced in width.
for a distance exactly equal to the width of the back strip b, which will leave a
shoulder on the top and bottom at each end of the fixed portion of the spring as
shown on Figs. 2 and 7.
The back portion of the springs behind the above mentioned shoulders are
provided with soldering tabs as is usual.
The springs and connections necessary to form a switch or spring jack are lai
together in their proper order, and the soldering tab ends are passed through the
rectangular hole before mentioned, the width of the springs being passed through
the hole at right angles to their ultimate position. These have now to be turned
on edge, and it will be found that as the springs are free to move on each other,
this can easily be done, and the shoulders on the springs fitting tightly against
the vulcanite strip 6 prevent any movement in the line of the springs. Spacing-
pieces or wedges o, o', &c. of vulcanite or other insulating material are then forced
between the springs to keep them rigidly in their proper positions Although not
absolutely essential the springs and connections n, n¹, n³, n, may be provided
with raised surfaces or pins as shown at e in Fig. 5 which will ride into hollows
in the spacing pieces or wedges o, ol, 02, 03, or a pin f, Fig. 6, which may be either
of metal or of an insulating material, may be driven through the centre of the
back pieco b into the wedge or spacing piece.
From the foreroine it will be seen that our invention renders unnecessary the
use of screws, with their attendant colletted springs, for fixing and building up
strips of spring jacks, and also does away with the use of adhesive materials for
keeping the springs in position.
Although we preferably construct our spring-jacks, or switches, on the principle
above described riz., with parallel strips, one carrying the springs and the other
the bushes, our invention may be applied to most of the well known patterns.
Our invention admits of modifications in construction, which would readily

page_text: suggest themselves to those skilled in the art, and we therefore do not limit
ourselves to the precise details of construction described herein.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare what our
claim is.
An improved method of constructing spring jacks or switches, substantially, as
herein before described, and shown on the accompanying drawings.
Dated this 27th day of August 1897
WILLIAM AITKEN.
DANIEL SINCLAIR.