An Improved Device for Facilitating the Connection and Disconnection of Electrical Conductors.
Year: 1891

page_text: COMELI TUIFICATION.
An Improved Device for Facilitating the Connection and
Disconnection of Electrical Conductors.
I, ALFRED LYSTER SHEPARD, of 8 West Kensington Gardens, in the County
of Middlesex, Electrical Engineer, 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 devices for facilitating the connection and disconnection
of electrical conductors, and is designed to improve and simplify the construction of
the same.
My said invention relates more particularly to wall-sockets, floor-connectors, and
similar electric fittings, that is to say, electrical-connectors wherein a movable plug
or the like provided with a pair of contacts electrically connected with wires or
conductors, is adapted to be readily inserted into and withdrawn from a fixed or
stationary socket provided with a corresponding pair of contacts electrically con-
nected with other wires or conductors, for the purpose of completing and inter-
rupting electric circuits.
With such electrical connectors as hitherto generally constructed, the plug must
be completely withdrawn from the socket in order to interrupt the circuit, and,
while the plug is out of the socket, any conducting body that may be accidently
or intentionally introduced into the said socket is liable to establish electrical
connection between the two contact-pieces of the socket and thus cause short-
circuiting.
By my present improvements, I overcome these defects or inconveniences, and
provide a device in which the circuit can be interrupted without completely with-
drawing the plug, and in which the risk of short-circuiting is obviated.
In the accompanying drawing, I have shown how my said invention may be con-
veniently and advantageously carried into practice.
Figure 1 is a longitudinal central section of a wall-socket and plug made
according to my present invention.
Figure 2 is a front elevation, the plug and the cover of the socket being
removed.
Figure 3 is a side elevation of the plug removed from the socket.
Figure 4 is a longitudinal central section showing another form or modification
of my improved electrical connector.
Figure 5 is a side elevation of the said electrical connector, the cover of the
socket being shown in section, and
Figure 6 is a front elevation, the plug and the cover of the socket being
removed.
Like letters indicate corresponding parts throughout the drawing.
a is the base and a' the cover of the socket; is the body and the cover
of the plug. c, c' are contacts or contact-pieces attached to the base a and having
their operative surfaces concentric with each other. d, d' are contacts or contact-
pieces attached to the plug b. These contacts d, d' are insulated from each other
by a tube e of wood or other suitable insulating material.
The contact d is a
conducting tube, lining or rod of brass or other metal; and the contact d' is
another conducting tube of brass or other metal, which surrounds the non-
conducting tube e concentrically with the inner tube or lining d. In the cover a¹ of
the socket or fixed portion of the device, is formed a hole a² into which the plug
may be introduced.
The contact-piece c is secured to the base a and is formed with a split or inter-
rupted ring adapted to receive and grip the exterior metal tube or contact piece

page_text: of the plug.
The contact-piece c' is also secured to the base a, and is adapted to
receive and grip the corresponding end of the inner tube d. This contact-piece is
slit as shown in Figure 2, so that it will be slightly expanded when the tube d is
pushed into it.
A short pillar or stud f of metal (or other suitable material) is fixed in the base a
and is adapted to enter the inner tube d of the plug or movable portion of the
device. This pin or stud f serves to steady the plug and to guide it so as to ensure
the entrance of the tube d into the aperture in the contact-piece c' when the plug is
pushed home in the socket, and also to increase the surface of contact. I prefer to
slit the said pin or stud as shown, to facilitate its entrance into the tube d. I prefer,
moreover, to slit the lower end of the said tube d, so that, when it is forced upon
the pin or stud f, it will be slightly expanded thereby and thus held in close
contact with the piece c¹.
The pin or stud fis separate from the contact-piece c¹ and does not conduct the
current except when it is connected by the tube a to the contact c. It, therefore,
serves very effectually to obstruct the entrance of any conducting body into the
socket when the plug is completely withdrawn therefrom, thereby preventing short-
circuiting.
As a further precaution, I prefer that the contact-piece e' should be let into the
base a so that it is flush with the surface thereof, and should be covered with a
piece of vulcanized fibre or other suitable non-conducting material, having a hole
to permit the introduction of the tube d into the contact-piece c¹.
The inner tube d of the plug is connected through a terminal g with one of the
circuit wires or conductors, and the outer tube d¹ is connected through a terminal g¹
to the other of the said wires or conductors. The positive and negative leads are
connected respectively to the contacts c, e through the terminal 92, 3. Therefore,
by pushing the plug home in the socket, the necessary electrical connections between
the conductors is established, and the contact-pieces c, c, d, d¹ will make equally
good contact in whatever position the plug is inserted; moreover, by reason
of the conducting or contact pieces being arranged concentrically, such electrical
connection will not be interrupted by the turning of the plug in the socket.
It is evident that, in the apparatus shown in Figures 1 to 3, if the plug is
drawn out sufficiently to remove the inner tube d from the contact-piece c', the
circuit will be interrupted without the necessity for entirely withdrawing the said
plug.
In Figures 4 to 6, I have shown a modification of my invention wherein I
provide for the interruption of the circuit by the partial rotation of the plug. For
this purpose, I make the contact c with a series of inclined surfaces c², and I provide
the plug with a pin or stud adapted to bear against one or other of the surfaces c²
when the plug is inserted into the socket.
It will be seen that, when the plug is in the position shown in Figure 4, the
tube d fits into the contact-piece c. By turning the plug about its axis from this
position through a small angle, the pin or stud is caused to ride up the inclined
surface and thus move the plug outward to the position shown in Figure 5, so as
to withdraw the tube from the contact-piece . I prefer to provide, in com-
bination with each of the inclined surfaces, a stop e³ for preventing the turning of
the plug through an angle greater than that required to effect the interruption of
the circuit.
It is obvious that the construction of my improved device may, if desired,
be somewhat further modified without departing from the nature of my said
invention.
For instance, the pin or stud fmay be dispensed with if desired. The contact-
piece d may, in this instance, be a solid rod instead of a hollow rod or tube. In the
case of floor-connectors, I find it advantageous to dispense with the said pin or stud,
and to form a hole through the base of the socket, through which any dust may
fall instead of accumulating in the contact-piece c'.
By the improved construction above described, I provide a device having only a

page_text: single aperture in the fixed portion or socket for the reception of the plug or
movable portion of the device, so that the said fixed and movable portions can be
very readily connected together without liability to injury of the contacts, and an
efficient contact will be ensured in whatever position the plug may be inserted.
By my improvements, moreover, I prevent, as above stated, the short-circuiting
which might otherwise be caused by the insertion into the socket of any conducting
bodies such as would form an electrical connection between the concentric contact-
pieces of the socket.
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 :-
First. An electrical connector wherein concentric contact-pieces on the one part
are adapted to enter concentric contact-pieces on the other part substantially as
herein before described, and which is so constructed as to obviate the risk of short-
circuiting, as above specified.
Second. An electrical connector such as I have hereinabove described, which
is so constructed that the interruption of the circuit can be effected by the
partial withdrawal by rotation of the plug or movable portion of the device.
Third. The combination of the concentric annular contact-pieces c, c¹ in the
socket, and the concentric contact-picces d, d' on the plug adapted to enter those
in the socket, as hereinbefore described and for the purposes specified.
Fourth. The combination, with the concentric contact-pieces in the socket, of a
pin or stud fixed in the base of the said socket but insulated from the said contact-
pieces, and adapted to enter the inner contact-piece of the plug, substantially as,
and for the purposes, above specified.
Fifth. The improved electrical connector constructed substantially as described
with reference to Figures 1, 2 and 3, or with reference to Figures 4, 5 and 6 of the
drawings for the purposes above specified.
Dated this en day un ray
1001.
A. L. SHEPARD.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.