An Improved Electric Switch.
Year: 1890

page_text: Date of Application, 8th Nov., 1890-Accepted, 13th Dec., 1890
COMPLETE SPECIFICATION.
An Improved Electric Switch.
I, GEORGE FREDERICK REDFERN, of the firm of G. F. Redfern & Co., of the
General Patent Office, No. 4, South Street, Finsbury, in the County of Middlesex,
Patent Agents, do hereby declare the nature of this invention (a communication
from abroad by Adolf Schirner, of 72, Brunnenstrasse, Berlin, in the Empire of
Germany, Electrician,) 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 an improved electric switch, the object of the improve-
ments being to provide a switch which will effect an instantaneous switching without
necessitating the employment of special springs; the construction of the switch key
also allows of the efficiency of the switch being greatly increased without its general
dimensions being enlarged by simply increasing the sections of the conducting parts.
The proportionately large contact-surfaces are cleaned by the act of switching and will
be in contact at all parts of their surfaces.
According to this invention a switch key is employed which is provided with
inclined sliding surfaces between or at both sides of the contacts whereby on the
switching key being turned the current is instantaneously switched on or off without
the employment of special springs being necessary and at the same time the contact
surfaces are cleaned. Switches of the same dimensions can be used for currents of
varying degrees of strength by increasing the drop or fall from one inclined surface
to the next and by increasing the section of the conducting parts.
In order to enable the invention to be fully understood I will proceed to describe
the same by reference to the accompanying drawing, in which
Figure 1 is a front view of the improved switch.
Figure 2 is a side view, and
Figure 3 is a plan.
Figure 4 is a section on line x, x of Figure 3.
Figure 5 is a side view of the switch key showing the upper contact spring
separated from the key.
Figure 6 is a plan of the switching key with the lower contact springs separated
therefrom, and
Figure 7 is a view of a modified form of switch.
The bottom plate A is provided with holes and grooves for the passage of the
conducting wires to the contact springs and has mounted upon it the lower spring
contact pieces a, al and the upper spring contact pieces b, which receive between
them the switch key B which is made to turn on the bottom plate. The switch key B
is of non-conducting material with an annular body c provided on its upper and lower
surfaces with inclined sliding surfaces of which the two upper surfaces d, e and two
lower surfaces d', el are connected by a strip f of conducting material, while the other
sliding surfaces i, i¹, k, k¹ present to the contact pieces surfaces of non-conducting
material.
For stronger currents the contact making sliding surfaces d, d¹ and e, e¹ should
preferably have a greater incline than the surfaces for breaking contact. By varying
the height of the drop or fall g, g, h, h¹ between one inclined surface and another the
switch can be rendered suitable for currents of different degrees of strength without
increasing its size when the sections of the conducting parts, videlicet, the
contacts a, b, a, and the contact surface strip f are made to correspond with
the strength of the currents.
The contact pieces a, b, a¹, 6¹ are adapted to the sliding surfaces and are compressed
by turning the switch key so that when they reach the end of the inclined surfaces at
the points g, g, h, h' they at once spring onto the next lower sliding surface and thus

page_text: instantaneously make or break contact according to the conducting or non-conducting
nature of the surfaces with which they come into contact.
The inclined form of the sliding surfaces together with the corresponding shape of
the spring contacts not only provides proportionately large contact surfaces which are
cleaned automatically by the act of switching but also ensures perfect contact of
every part of such surfaces.
The switch is preferably provided with a cover as shown in Figure 4 in order to
protect the working parts from damage by dust and the like.
Although I have described the switch key as rotating while the spring contacts are
fixed it will be obvious that the spring contact pieces can rotate and the switch key he
fixed. This modification is shown in Figure 7 in which the switch key is formed in
two parts B', B which are so arranged that the sharp edges of the inclined surfaces
point towards one another and have between them the insulated contact pieces b, b', a, a¹
connected to the central axis (!.
It will thus be seen that the action of the modified form of switch is the same as
that of the switch herein before described and possesses the further advantage that
when very strong currents are employed where the contact pieces are of a size which
prevents them acting as springs, the divided switch key can be made to spring on its
axis, the two parts of the switch piece being provided with springs which at a given
moment cause the parts of the switch piece to approach one another and thus to make
or break contact.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
(1.) In an electric switch the combination of angular shaped spring contact pieces
with a switch key having inclined sliding surfaces for the said spring contact pieces on
the outer side (Figure 1) (or when the switch key is divided as in Figure 7 on the
inner facings) for the purpose of providing a large surface contact and allowing of the
current being instantaneously switched on or off and a simultaneous cleaning of
the contact surfaces without employing special springs therefor the arrangement also
allowing the switch to be used for currents of various degrees of strength by
increasing the height of the fall from one inclined surface to another and
correspondingly increasing the sections of the conducting parts, substantially as
herein before described.
(2.) The improved electric switches substantially as herein before described and
illustrated in Figures 1 to 7 of the accompanying drawing.
Dated the 8th day of November 1890.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.