Improved Electric Light Switch.
Year: 1892

page_text: Date of Application, 5th May, 1892
Complete Specification Left, 4th Feb., 1893-Accepted, 15th Apr., 1893
PROVISIONAL SPECIFICATION.
Improved Electric Light Switch.
I, WILLIAM EDWARD LANGDER Superintendent, Electrical Department,
Midland Railway, Derby, do hereby declare the nature of this invention to be
as follows:-
In an improved electric light switch.
In order to effect this I arrange a plunger rod working within a groove or tube
having at one end a button or press piece, and at the other end a tongue or small
lever, with a limited lateral movement on either side. The rod carrying the press
button and tongue is connected with a helical spring arranged within the same
tube, the action of which is to force the rod in the direction of the press button.
The tongue I maintain normally in the direction of the rod by means of a suitable
spring or springs.
Immediately above this tongue, centred in a line with the direction of the
plunger rod, I provide a contact lever having on either side of its centre a semi-
circular shaped arm and immediately under its centre a double inclined plane, the
apex of which is when the contact lever is in a line with the tongue central with
the same.
The position in which this contact lever shall lay I control by a spiral spring so
arranged that when the lever is in one direction the spiral spring shall be moved
over its centre, or that position in which it is at its utmost tension, and when the
lever is moved in the other direction the spring shall again be carried over its
point of utmost tension, and thus, in which ever position the lever is placed, it shall
there be retained by the tension of the said spiral spring.
At a convenient position I arrange two insulated contact springs to which I
attach the circuit wires in connection with the electric light.
The action of the switch is the same to turn the light on or off. The button
merely requires pressing. The spiral spring having carried the contact lever over
into-say, the off position-on the button being pressed the tongue will pass to
one side of the apex of the double inclined plane until it presses against the semi-
circular arm which it will then force away from it, thereby carrying over the
contact lever till the spiral spring has passed its point of greatest tension, when it
will, in combination with the action of the plunger, force the contact lever between
the circuit springs and complete the lighting circuit. The apex of the inclined
planes will now be on the opposite side of a line direct with the action of the
plunger rod, and if the plunger be now pressed the tongue will traverse the opposite
inclined plane and the movement of the contact lever will be reversed, the lighting
circuit thereby being broken and the light turned off.
Dated this 4th day of May 1892.
WILLIAM EDWD. LANGDER.
COMPLETE SPECIFICATION.
Improved Electric Light Switch.
I, WILLIAM EDWARD LANGDER Superintendent, Electrical Department,
Midland Railway, Derby, 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 an improved electric light switch, and has for its object
the making and breaking of the electrical contact by means of a similar movement
in one direction in both cases

page_text: In order that my invention may be clearly understood, I have appended the
accompanying sheet of drawings, in which
Figure 1 is a side elevation in section of a suspension switch,
Figure 2 a front elevational view of the contact bar and movement thereof,
corresponding thereto, and
Figure 3 is an elevation of the switch with the cover or case in position.
Although in the drawings, I have shewn my invention as adapted to a suspended
switch, I may adapt the same mechanism to any other form of switch that may be
suitable.
Similar letters of reference indicate corresponding parts throughout the several
views.
In carrying my invention into effect, I arrange a plunger rod d working within a
groove or tube, having at one end a button or press piece E, and at the other end
a spring tongue c, or a hinged lever with guard springs on both sides may be sub-
stituted therefor. The lateral movement on either side is limited by the manner
in which the end of the plunger d is grooved, as shewn by Figure 2, and said
tongue c, is maintained in the same plane as the plunger when in its normal
position. A spiral spring e serves to keep the plunger d in said position, its
tension being against the pressure upon D. Above the tongue c, and centred in
the same plane, I provide a contact lever g. pivotted at a, having on both sides of
its centre a semicircular shaped arm 6 Figure 2, and between these, and centrally
placed below a, a double inclined plane f. the apex of which is, when
is in a
direct line with the tongue c, central with the same.
I may use a spiral spring, or any other kind of spring or springs to retain, by
slight tension, the contact lever g in either position, or I may dispense with springs
and depend upon the good fit of the pivot a to effect the desired retention therefore
I have not particularised the spring in the appended drawings.
The contact brushes h h¹ are insulated from each other, and from the metallic
body of the switch, and are each connected to terminal screws for the purpose
of coupling to the leads. The cap B serves to hold the upper hemisphere of the
case C in position, and a flange D fulfils the same function with regard to the
lower hemisphere of said case.
The action of the switch according to my invention, may be described as
follows:-
The contact arm 9 being in either position, pressure upon E causes the tongue c
to be raise, and it is diverted by either of the inclined planes off so that it
forces g into the opposite position, which in Figure 2 is that of contact, and is
indicated by a dotted outline. When this is done, and the pressure removed from E
the plunger d is returned to its normal position by the spring e and the tongue c
also resumes its normal position. The apex of f is now, however, so situated, that
a second pressure upon E causes c to be guided into the opposite recess of b', so
that both movements of g are effected by moving E in the same direction.
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 1
claim is,―
First. In an electric light switch the combination of a pivotted contact lever g
having extensions bb', and f, with a plunger d and spring tongue c substantially
as herein described with reference to the drawings.
Second. In an electric light switch the arrangement of the parts referred to in
the preceding claim, in such a manner, that making or breaking the electric circuit
is performed by pressure upon E, with or without a retention spring or springs,
substantially as herein described with reference to the drawings.
Dated this 23rd day of January 1893.
WILLIAM EDWD. LANGDER.