ROVEMENTS IN ELECTRIC LIGHT SWITCHES
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by the said Charles Maynard at the
Office of the Commissioners of Patents on the 18th November 1882.
CHARLES MAYNARD IMPROVEMENTS IN ELECTRIC LIGHT SWITCHES
In most or so far as I know in all switches for Electric Currents made hitherto
the arm or lever is fixed to an axle working on its centre and liable to become
unscrewed or loose in its action and therefore involving risk of the contact at the
plates or studs being ineffective.
In my improved switch I use a double arm of metal B turning as if pivotted at
its centre and making simultaneous contact at the two side plates A. A. Instead
of this double arm actually turning on an axis at B as in other switches I fix it to
the bottom of a disc of wood or other material turning round inside a ring of
similar material and allowing the ends of this arm simultaneously to make or break
contact with the side plates A. A. I cut away sufficient of this ring underneath at
opposite sides to allow the arm a limited movement sufficient to make and break
contact effectually at both ends.
Having described the article that contains my improvement I declare that
I claim
First. The fixing of the arm of the switch to the underside of a rotating disc
which though not fixed on a pivot at its centre revolves truly being confined by an
outer ring.
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Second. The fixing of the contact or terminal plates at the underside of this so
that when the disc revolves the ends of the arm necessarily rub on these plates and
make effective contact.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Maynard in the Great Seal Patent Office on the
25th April 1883.
CHARLES MAYNARD of 10 Ann Street Islington
LIGHT SWITCHES"
"IMPROVEMENTS IN ELECTRIC
In my improved Switch I use a double arm of metal B. turning as if pivotted at
its centre and making simultaneous contact at the two side plates A. A. Instead of
having this double arm actually turning on an axis at B. as in other switches I fix it
to the bottom of a disc of wood or other material turning round inside a ring of
similar material, and allowing the ends of this arm simultaneously to make or break
contact with the side plates A. A.
In some I cut away sufficient of the ring underneath at opposite sides to allow
the arm a limited movement right and left.
In others however I limit the movement of the arm as in fig. 5. when on the
contact plates by a stud or banking piece and when off by the screws which pass
through the holes at D to fasten the switch to the wall. This figure shews the
underneath side of the switch.
I also, to secure the actual contact plates from being burnt by the sparking caused
by the breaking of the current fix a second plate (a) on the top (see Fig: 7) so that
any sparking at the double arm will occur at (b. b.) those being the last points of
contact and therefore the lower contact plates will be always bright and uninjured.
I do not however consider this means of preventing the contact being damaged
by sparking to be new such being used before in Eidsforth's switches which are
not covered by a Patent, but I claim the use of such means of preventing the
burning of the contact plate in conjunction with my Invention as aforesaid.
Fig: 6, shews the general appearance of my switch in section.
What I claim therefore is:
1st The fixing of the arm of the switch to the underside of a rotating disc, which
though not fixed at its centre, revolves truly, being confined by an outer ring.
2nd The fixing of the contact plates at the underneath of this ring so that when
the disc revolves the ends of the arm necessarily rub on these plates and make
effective contact.
In Witness whereof I the said Charles Maynard have hereunto set my hand
and seal this Thirty first day of March in the year of our Lord One
thousand eight hundred and eighty-three.
CHARLES MAYNARD (L.S.)