Improvements in the Construction of Electric Light Switches, Cut-outs, Ceiling Plates, Wall-connectors, Lampholders, and the like.
Year: 1892

page_text: Date of Application, 14th Sept., 1892-Accepted, 15th Oct., 1892
COMPLETE SPECIFICATION.
Improvements in the Construction of Electric Light Switches,
Cut-outs, Ceiling Plates, Wall-connectors, Lampholders, and
the like.
We, CHARLES MARK DORMAN of Ordsal Electrical Works, Salford in the
County of Lancaster, Electrical Engineer and REGINALD ARTHUR SMITH of
Ordsal Electrical Works, Salford in the County of Lancaster, 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 improvements in the details of electric light switches
and also of such electrical apparatus as are provided with metallic covers screwed
on to bases or which are fitted with terminals for the attachment of wires such as
cut-outs ceiling plates, wall-connectors, lampholders and similar articles.
Our invention consists partly of an improved method of forming a screw thread in
the covers of such articles, partly of an improved terminal for the attachment of
the wires or cables, and partly of an improved method of making the contact arms
in switches.
Referring to the drawings accompanying this Specification:-
:-
Fig. 1. is a section on the line of a switch fitted with our improved cover and
contact arm.
Fig. 2. is a plan with cover on, and
Fig. 3. a plan with cover removed of same switch.
Fig. 4. is an underplan of the handle.
Fig. 5. is a view of the flat sheet metal blank from which the finished contact
arm shown in Figs. 6. and 7. is bent.
Fig. 8. is a section and
Fig. 9. a plan of our improved terminal.
In metallic cases-preferably spun or plunged out of sheet metal and which can
be plain or ornamental in design as desired-we insert and fix a separate spiral
screw thread shown in section at a. in Fig. 1. This spiral nut is made from
triangular or other required section of solid, hollow, or channelled metal, and is
preferably formed by winding the same round a cylindrical or screwed mandril of
the required size The finished spiral is then securely fixed inside the metallic
cover thus forming a female screw which can be screwed on in the ordinary manner to
any base provided with a suitable male thread. We do not confine ourselves to the
shape of thread shown at a. in Fig. 1, but sometimes use round, square, and other
sections of thread.
Our improvements in the contact arms of switches consist in stamping from
sheet metal a blank of the approximate shape shown in Fig. 5. and bending the
same in suitable presses until it assumes the shape shown in Figs. 1. 6. and 7. at b.
The finished contact arm b. which is held down by and revolves round the central
peg c, screwed directly into the base f. is actuated by means of a handle g. pivotted
on the same peg c. The projecting parts d. d. of the contact arm b. engage in the
recess e. of the handle g, and a quick break is obtained by means of the spring h.
which embraces the projecting parts d. d. as described in our Specification No. 16578
of 1886. The contact arm shown in the drawings is for single break switches
but our improvement is also applicable to double break switches by adding
another arm opposite to or at a suitable angle with the single arm shown."
Our improved terminal consists of a hollow bolt k. screwed directly into the base f.
and securely gripping the switch tongue m. between a thick washer 1. and the base f.
The connecting wire which passes through the base f. and the hollow bolt A. is gripped

page_text: up by the terminal screw n. This form of terminal is equally applicable to the parts
of cut-outs, ceiling plates, wall-sockets, lampholders and similar electrical apparatus,
and we do not confine ourselves to its use in switches only.
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 switches, cut-outs, ceiling plates, wall-sockets, lampholders, and similar
electrical apparatus which are provided with a metallic cover screwed on to a base
the method of forming a nut by bending solid, tubular, or channelled metal of
triangular or other suitable section into the form of a spiral, the spiral nut so
formed being afterwards securely fixed inside the metallic cover thereby forming a
female screw thread in the cover substantially as and for the purposes described.
2. In electric switches the method of forming a contact arm by bending a flat
sheet metal stamping into the required shape and arranging projections on the same
to gear with the handle and spring substantially as described and shown in the
drawings accompanying this Specification.
3. In switches, cut-outs, ceiling plates, wall-sockets, lampholders and similar
electrical apparatus the method of forming a connecting terminal for solid wires or
cables by means of a hollow bolt screwed directly into the base of the apparatus which
hollow bolt securely grips the part of the apparatus to which the terminal is attached
between a thick washer and the base of the apparatus, the connecting wire or cable
passing through the hollow bolt being gripped by a set screw substantially as
described and shown in the drawings accompanying this Specification.
Dated this 13th day of September 1892.