Improvements in Telephone Switch-boards.
Year: 1890

page_text: Date of Application, 10th Feb. 1890
Complete Specification Left, 8th Nov., 1890-Accepted, 17th Jan.. 1891
PROVISIONAL SPECIFICATION.
Improvements in Telephone Switch-boards.
I, DUNCAN DEWAR, of Antwerp, in the Kingdom of Belgium. do hereby declare
the nature of this invention to be as follows:-
My invention relates to telephone switch-boards chiefly designed for use in
telephone exchanges.
It is well known to persons familiar with telephone switch-boards that any
derangement arising from the wear of the working parts disables one operator's
apparatus on the switch-board while repairs are being made to one key, such repairs
involving the cutting or severing of connections, and the remaking of which is an
extremely difficult operation.
My invention has for object to render such a difficult operation unnecessary by
providing a novel construction of combination switch usually known as the listening-
key, its function being to alternately switch the operator's telephone and clearing-out
drop in between two telephone lines, the connections or disconnections being made
by pulling or pushing a lever.
In carrying out my invention I arrange the switch-lever to oscillate in brackets
and act upon hinged pieces of brass or other suitable metal carrying two hard rubber
or ebonite discs with beveled edges and provided with studs of rubber or metal at
their backs. These hinged pieces on being separated by the lever assume an angular
position with regard to each other and act on springs and connections and lock the
key in position until released by the lever being moved in a contrary direction; the
said parts are mounted on a detachable block of hard rubber which is attached by
means of screws to the main block or piece carrying the springs and connections.
By simply removing the said. screws and detaching the rubber handles of the levers,
the lower block with its attachments can be lowered, the worn parts renewed and the
whole replaced without involving any great delay to the operator.
Dated the 10th dose of Rahma 1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Telephone Switch-boards.
I, DUNCAN DEWAR, of Antwerp, in the Kingdom of Belgium, 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 :-
My invention relates to keys or switches chiefly designed for use on telephone
switch-boards.
On a telephone switch-board for exchange purposes there is usually provided a
switch generally known as the listening or speaking key and hereinafter referred to
as the key, the object of which is to bring into a given circuit either the operator's
telephone or a clearing-out drop, the alternative purposes being effected by pulling
or pushing a lever. A number of such keys being in electrical connection with one
operator's telephone it is desirable that in the event of any repairs being needed to
any key they should be effected without disturbing the circuit of the operator's
telephone. Heretofore keys have been so constructed that the electrical connections
and the working or wearing parts form one fabric, hence repairs effected to one key
were liable to involve the cutting or severing of electrical connections which, in turn
involved the throwing out of work of one operater's telephone set. Furthermore
the remaking of such connections was a difficult operation.

page_text: According to my present invention I construct a key in such a manner that the
electrical connections and the wearing parts are on separate bases, thus enabling the
wearing parts to be readily removed, repaired, and replaced without disturbing
the electrical connections.
To enable my invention to be fully understood I will describe the same with
reference to the accompanying drawings, in which :-
Figure 1 is a view of one end of my improved key:
Figure 2 is a side view :
Figure 3 is a view of the opposite end of the key to that shewn in Figure 1:
Figures 4 and 4ª shew the fixed and detachable parts of my improved key:
Figure 5 is a plan view of the detachable part shewn by Figure 4" :
Figure 6 is a top view of my improved key, certain parts being indicated by
dotted lines.
Similar letters of reference indicate corresponding parts in the several figures.
a is the top part of the key, which part is composed of a block of ebonite or other
insulating material and may be considered as permanently attached to the switch-
board, and the removable part also composed of insulating material, containing or
carrying the wearing parts of the key, and being adapted to be secured to the
part a by screws c, c.
d, d', d², Figure 4, are strips forming the electrical connections and to which the
various circuit wires may be permanently attached, and d³, d³ are springs operating
in a well known manner.
e is a lever mounted in brackets f,f secured to the part b, as shewn in Figures 1,
2, 3 and 4, the said lever being capable of having a to-and-fro movement imparted
to it, as shewn most clearly in Figure 2.
9, 9 are arms located in a recess in the part and provided with pins or
studs h, h constituting pivots upon which the said arms move, the said pins or studs
entering holes in the parts a, b. The arms 9, 9 may be made of any suitable
material but in practice I preferably use metal and place at the end of each arm a
disc or button of ebonite or other suitable insulating material, the said discs
having studs, which are inserted into holes or recesses in the said arms.
These arms are so arranged that when the lever is moved between them they act
upon the springs d³, d³ in a manner well understood and needing no description,
the said lever acting as a wedge to separate one arm from the other, the discs with
the springs then acting to retain the lever in its position until released by the
operator.
The edges of the discs are beveled in order to allow the lever to move freely
between them.
Assuming the key to be attached to the switch-board and to need repair or
renewal in the wearing parts it will be obvious that, in order to remove the parts
shewn in Figure 4" from those shewn in Figure 4, it is only necessary to remove the
knob from the lever e and to take out the screws c, c, the said lever passing
through the channel provided for it in the part a.
In the foregoing description I have not deemed it necessary to describe the
electrical connections and the action of the springs since they are well understood.
I wish it to be understood that although I have only described my improved
switch as a listening or speaking key it is applicable for other purposes in which
similar divisions of electrical circuits are to be made.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a key or switch, constructing the said key or switch in two parts which are
readily detachable, one of the said parts carrying the electrical connections while the
other carries the working or wearing parts, substantially as, and for the purpose,
specified.
2. In a key or switch, the combination with the supporting block or blocks of a

page_text: bracket carrying a switch-lever having a detachable handle, and two pivoted arms
carrying discs of insulating material, the said discs being beveled at their edges and
secured by studs, substantially as described.
3. The manufacture and use of the improved key or switch hereinbefore described
and illustrated in the accompanying drawings.
Dated the 8th day of November 1890.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.