Improvements in Electrical Switches..
Year: 1894

page_text: COMPLETE SPECIFICATION.
Improvements in Electrical Switches..
We, CHARLES MARK DORMAN, of Ordsal Electrical Works, Salford, in the
County of Lancashire, Electrical Engineer, and REGINALD ARTHUR SMITH of
Ordsal Electrical Works, Salford, in the County of Lancashire, 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 :-
Our invention relates to that class of switch known as tumbler switches in which
electrical contact is made between two terminals of the switch by means of a
hinged contact lever which is forced between the terminals by means of an actuating
lever, one end of which projects through the cover of the switch.
In the ordinary forms of tumbler switch, in order that the metallic actuating
lever and other metallic parts connected to it shall not be in electrical connection
with the terminals of the switch when the contact lever is in the "on" position the
contact lever is made of some insulating substance such as vulcanite or fibre with a
metallic tip or metallic plates attached at the end only which is forced between the
terminals. Our invention consists principally in an improved disposition of the
insulating substance which enables us to make the contact lever entirely of metal.
and consequently of a better and more durable design, and also enables us to use
an improved form of spring to hold the contact lever in the "off" position.
Referring to drawings
Fig. 2. is a plan of our improved tumbler switch with cover removed.
Fig. 1 is a sectional elevation on the line ry.
Fig. 3 is an elevation viewed from . with cover in section.
Figs. 4 and 5, are views of our improved sugar tongs spring contact lever.
Figs. 6. 7. 8. & 9. shew two forms of our improved actuating lever.
.
a. is the base of the switch of porcelain or other suitable non conductor on which
the metallic parts are mounted. The metallic parts are best fixed on the non con-
ducting base by the methods described in our Specification No. 11143, 1893. b. is
the contact lever which it will be seen is formed of a single piece of hard metal
bent round into a sugar tongs form. It will be seen that the contact lever bis
hinged on a pivot d. which is carried by two brackets e. e. These brackets are
fixed to the insulating base only and are not in electrical connection with the
metallic bracket m. which carries the actuating lever and cover. The brackets e. e.
are not essential, the pivot may be fixed direct in the insulating base or held in any
other convenient method so long as the pivot is not in electrical contact with the
bracket m. c is the actuating lever. It will be seen that the lever is provided
with metallic projections f. f. which gear into tlie slots y. g. in the contact lever and
move it into or out of the terminal jaws h. h. when the actuating lever is moved.
The projections f. f. are electrically insulated from the other parts of the actuating
lever. Figs. 6. 7. 8. 9 shew two methods in which this may be effected, by means
of insulating bushes and washers, the parts shewn black in section on the drawings
are made of insulating material. It is not necessary that the actual method of
gearing shewn be adhered to so long as the gearing device attached to the actuating
lever be insulated therefrom. k is a spring which is coiled round the pivot d. with
its torsion so arranged that it always exerts a pressure on the contact lever tending
to withdraw it from the contact jaws. The slots in the contact lever are so
:rranged that when the actuating lever is in the "on" position it holds the contact
iever firmly in the jaws against the action of the spring.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. In electrical switches of the tumbler type having a contact lever and actuating
lever the provision of a hinge or pin for the contact lever to turn upon which is not
in electrical connection with the metallic bracket which carries the actuating lever
and the cover the, electrical insulation between the contact lever and the handle of
the actuating lever and other metallic parts connected thereto being effected by
means of insulating material attached to the actuating lever at a point between the
pivot of the actuating lever and the contact lever.
2. In switches of the tumbler type the improved form of spring contact lever
formed out of one piece of metal bent round into a sugar tongs form.
3. In switches of the tumbler type the improved form of spring for holding the
contact lever in the off position formed of a wire coiled round the spindle on which
the contact lever is pivoted and so arranged as to hold the contact lever clear of
the contact jaws when not held in the jaws by the actuating lever substantially as
shewn in the drawings.
4. The improved tumbler switch as a whole substantially as described and shewn
in the drawings.
Dated this 23rd day of February 1894.
CHARLES MARK DORMAN.
REGINALD ARTHUR SMITH.