Improvements in connection with Switches for Telephone Circuits.
Year: 1889

page_text: Date of Application, 5th Apr., 1889
Complete Specification Left, 13th Dec., 1889-Accepted, 25th Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements in connection with Switches for Telephone
Circuits..
ALFRED GRAHAM of 109 Farringdon Road in the City of London Electrician
do hereby declare the nature of this Invention to be as follows:-
My Invention relates to switches of the kind in which a movable contact maker is
provided for making contact with a number of contact pieces or springs arranged in
line such for instance as that described in the Specification of Letters Patent No. 2251
granted to me and dated 14th February 1888 the object of my present Invention
being to provide in connection with such switches means whereby the return of the
contact maker to zero when the operator has finished using the instrument is
ensured.
According to my Invention I cause the release of the contact maker by means of
the telephone receiver when it is put in place after use. For this purpose I provide a
receiver holder or support consisting of a forked lever or the like by which the receiver
is supported its weight bringing the said lever into one position whilst a spring or its
equivalent brings the said lever into another position when the receiver is removed.
In connection with this lever I provide a spring or other device which when the
receiver is removed takes up a position such that when the receiver is again put in
place the said spring or device operates the detent or retaining device by which the
contact maker has been held in position for use so that the said contact maker returns
to its normal position of zero the movement of the said contact piece in returning to
that position effecting the return of the aforesaid spring or device to a position which
allows the detent or retaining device of the contact maker to operate to retain the said
contact maker in the position to which it may be brought when the said contact piece
is again operated for completing any desired circuit.
Datad this 5th day of Anril 1889.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in connection with Switches for Telephone
Circuits.
ALFRED GRAHAM of 109 Farringdon Road in the City of London 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 switches of the kind in which a movable contact maker is
provided for making contact with stationary contact pieces such for instance as
described in the Specification of Letters Patent No. 2251 granted to me and dated
14th February 1888 the object of my present Invention being to provide in connection
with such switches means whereby the return of the contact inaker to its normal
position is ensured when the operator has finished using the instrument for which
purpose according to this Invention the lever which supports the receiver when not in
use is provided with or attached to a spring or other device, which when the receiver is
removed from the lever takes up such a position, that when the receiver is again
placed on the lever, the spring operates the detent or retaining device by which the
contact maker has been held in position for use, so that the said contact maker returns
to its normal position of zero.

page_text: And in order that my said Invention may be fully understood I shall now proceed
particularly to describe the same, and for that purpose shall refer to the several figures
on the annexed sheets of drawings, the same letters of reference indicating corre-
sponding parts in all the figures.
Figure 1 of the accompanying Drawings is a front elevation of an apparatus con-
structed according to this Invention.
Figure 2 is a transverse section taken along the line 1. 2 in Figure 1, and Figure 3
is a view of the interior looking from the back, the back board being removed.
Figure 4 is a diagram shewing the lines communicating with the several switches in
the series. The switch shewn in the drawings is arranged for communicating with
nine other stations, each of which is provided with a similar switch. Each switch is
provided with stationary contacts formed by blade springs a preferably arranged in an
are of a circle on the back of the front board A with either of which contacts c, a
moveable contact B may be brought into contact as required. The moveable contact B
is mounted on the inner end of a spindle b, which passes through the front board A
and has fast on its outer end a handle C, by which the contact B may be moved, a
pointer c being also fixed on the spindle for indicating on a scale on the face of the
board which of the contacts are made.
Each switch contains one stationary contact a indicated on the scale by 0 (zero)
and has omitted from the scale the number of the station in the series to which
the switch belongs for example; as shewn in Figure 4. No. 1 switch contains
contacts marked 0, 2, 3, 4, 5 and so on (1 being omitted) No. 2 switch contains
0, 1, 3, 4, 5, and so on, (2 being omitted) No. 3 switch 0, 1, 2, 4, 5 and so on,
No. 4 switch 0, 1, 2, 3, 5, and so on, and No. 5 switch 0, 1, 2, 3, 4, 6 and
so on.
The switch shewn in the drawings has omitted from its scale, the number (5)
thus indicating that the switch belongs to No. 5 station of the series. The line
wires from the several stations in the series, enter the switch through a hole & in
the back board D) and are connected to spring contact plates e which when the
front board A is in position, make contact with spring plates thereon which
latter plates are connected by wires g with the stationary spring contacts a herein-
before referred to: On the spindle which carries the moveable contact B there
is a ratchet wheel E or part of a wheel having ratchet teeth with which engages
a detent carried by a lever F which is centred at i to the front board A. The
teeth on the wheel E are of such a shape as to admit of the wheel being turned
freely in either direction by, the, handle C. Surrounding the spindle is a spiral
spring having, one end, connected to the spindle, and its other end attached to
the lever F so that this spring serves to hold the detent in engagement with the
teeth on the wheel E, and also to return the moveable contact B to its normal
position as hereinafter described.
To explain the operation of the apparatus let it be supposed that it is required to
communicate from No. 5 station (that shewn in the drawing) with one of the distant
stations, say for example No. 3. The attendant at No. 5 station first turns the
moveable contact B, by means of the handle C into contact with the stationary
contact a, corresponding to No. 3 on the scale, in which position the piece B is
retained by the detent engaging the teeth of the ratchet wheel E, then by depressing
the button G, so as to make contact of the tongue with the bridge piece a circuit
will be completed through the line No. 3 (Figure 4) which will ring the bell at No. 3
station if the apparatus at that station is disengaged. The attendant then removes the
telephone receiver J from the hook of the switch lever K which under the action of a
spring will be raised so as to cause a projection w. thereon to make contact with
spring contact pieces at m and whereby circuits are completed through the telephone
transmitters I and receivers J of both stations so that conversation between the
attendants at the two stations may be maintained. Projecting from the ratchet
wheel E is an arine, the outer end of which when the contact B is in its normal position
at 0 (zero) bears against a blade spring carried by a slide which is raised and

page_text: lowered with the switch lever K. When the moveable contact B is moved into contact
with either of the stationary contacts a other than that marked 0 (zero) the end of
the arm w-leaves the blade spring u which then springs forward bringing its lower end
over the outer end of the lever F, carrying the detent .
in
When the attendant has finished using the receiver he hooks it on to the lever K
which will then descend by the weight and break the circuit through the telephone
receivers and transmitters and make contact at s in connection with the bell
readiness, to be called and at the same time by the descent of the lever K, the slide t
carrying the blade spring is also lowered, so that the lower end of the said spring
pressing on the end of the lever F disengages the detenth from the teeth of the
wheel E which will then under the action of the spiral spring be partially rotated
and thereby return the contact B to its normal position 0 (zero) the tail end of the
lever v coming again into contact with the blade spring and pressing back the said
blade spring u out of the range of the lever F so as to admit of the detent / again
engaging with the teeth of the ratchet wheel E in readiness for the next operation.
In order to indicate when calling up a distant station, whether or not the apparatus
at the station with which it is required to communicate is disengaged, there may be
placed in the circuit and within sight or hearing of the operator, a visible or an audible
indicator which if the apparatus at the distant station be unoccupied will be operated
by the vibrations of the bell mechanism at the distant station but if the moveable
contact B of the apparatus at the distant station, has been moved for the purpose of
communicating with one of the other stations in the series the indicator will remain
undisturbed as the bell circuit will have been broken.
If however the contact B at the distant station be in its normal position at zero,
and the receiver J at the said station is in use then the indicator will be only slightly
affected but sufficiently to indicate that the apparatus is engaged.
In Figure 3 is shewn at 1 an audible indicator and at 2 in Figure 1 is shewn a
visible indicator for this purpose but I do not restrict myself to the arrangements
shewn as they may be considerably modified.
The audible indicator shewn in Figure 3 consists of a coil 3 placed in the circuit
and attached by a bracket 4 to the back of the front board A of the switch. Opposite
the coil 3 is suspended from the bracket 4 an armature 5. When the button G is
depressed for the purpose of calling up a distant station and the instrument at that
station is disengaged the bell circuit at that station will be completed through the
coil 3 and the armature 4 will be caused to vibrate against the core of the coil
which will be heard by the attendant and thus indicate that the distant station is at
liberty. If the moveable contact B of the instrument at the distant station has been
moved away from its position at zero for the purpose of calling up some other station
the bell circuit at that station will be cut out and consequently no current will pass
through the coil 3 and the armature 4 will remain stationary and no sound be heard
thereby indicating that the distant station is engaged. If the moveable contact Bat
the distant station be in its position at zero but the receiver J has been removed from
its hook the current will be short circuited through the coil 3 and cause the
armature 4 to be attracted against the core of the coil 3 giving thereby one sound
only thus indicating that the distant station is being spoken with.
In like manner
the pointer 6 of the visible indicator 2 Figure 1 is caused to vibrate with the
armature (4) or to remain stationary as the case may be and thus visibly indicate the
condition of the distant station.
Having now particularly described and ascertained the nature of iny said Inven-
tion and in what manner the same is to be performed I declare. that what I
claim is :-
First. In a switch for telephone circuits, the combination of an adjustable contact
piece and a number of stationary contact pieces each in circuit with a separate
and distinct telephone apparatus, a ratchet wheel and detent or equivalent device
for retaining the movable contact piece in its adjusted position and means for
releasing and returning the movable contact piece to its normal position by replacing
'

page_text: after use the telephone receiver ou its support, substantially as herein before described
with reference to the accompanying drawings.
Second. In switches for telephone circuits the combination of the stationary contact
pieces a in the circuits of separate and distinct telephone apparatus the adjustable
contact piece B, the ratchet wheel E, detent h and lever F for retaining the contact
piece B in its adjusted position, the spring for holding the detent h in engagement
with the ratchet wheel E, and for returning the moveable contact B to its normal
position, when the detent is disengaged from the wheel E, the whole being arranged
to operate substantially as herein before described.
Third. The combination with the subject matter of the preceding claiming clause
of a visible or an audible indicator in the circuit of the switch for indicating
whether or not the apparatus at a distant station is engaged substantially as herein-
before described.
This 19th day of Danmhan 1000