Improvements in Electric Switches.
Year: 1892

page_text: Date of Application, 1st Nov., 1892-Accepted, 3rd Dec., 1892
COMI LEIE DIECITIUATION.
Improvements in Electric Switches.
ALEXANDER BEWICKE BLACKBURN of 51 Withington Road Manchester
Member of the Institution of Civil Engineers, 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 :-
In an electric switch, purchase is obtained, for the fingers to operate it, by means
of two handles which are brought closer together on being pressed, and on being
released are separated, by means of a spring acting between them, or by the force
of gravity. Once in each to and fro movement the opening or closing of the circuit
is thereby effected.
The other portions of the necessary mechanism may consist of any known or
suitable arrangement, the whole forming a combination of which that described as
follows, and shewn in the accompanying figures may be taken as an example.
A tooth or pawl attached to a moveable lever, one extremity of the said lever
forming one of the handles, the other handle being attached to the switch case; a
spring between the two handles to separate them; engaging with the tooth or pawl
a ratchet wheel, which is rotated one step by the tooth or pawl each time the
handles are brought together. Contact pieces attached at equal distances round
the ratchet wheel and connected to one pole of the source of current; one of these
pieces, at one step brought up to a fixed insulated contact piece, to which is connected
the other pole of the source of current; at the next step, the moving piece carried
beyond the fixed piece, thereby opening the circuit; at a further step another
of the moving pieces brought up to close the circuit and so on in endless
succession.
Fig. 1, shews in elevation, an incandescent lampholder of the ordinary "bayonet"
type with such handles, marked Z & Z, applied.
L, is rigidly attached to the case and L', is moveable relatively thereto, and
works in a slot formed in the case. Fig. 2, shews the same in sectional elevation,
and Fig. 3, in plan. A & A¹, Fig. 2, are terminals to which the leading in wires
are attached, P & P¹, are spring pistons of the usual description, which convey
current to the lamp. B, B, B, is a body of porcelain or other suitable insulating
material, the upper portion of which is somewhat reduced in diameter and forms a
pillar on to which loosely fits a crown wheel W. A' & P¹, are connected by a
metallic stem, shewn in dotted lines, which passes through the body, and P. is
similarly connected to a metallic block or fixed insulated contact piece N. Eight
teeth are cut on the upper rim of the crown wheel W, and to its lower side are
attached 4 contact pieces T, one of which is shewn resting on the block N. A
helical ribbon spring S, is held at one extremity under the terminal A, and the
other extremity rests on a shoulder, formed on the inner face of the crown wheel;
the piece T, is thus pressed against the block N, and the current is at the same
time conveyed by the spring from the terminal A, to the piece T, and thence to the
block N. If it be desired to avoid metallic connection between the parts carrying
the current and the crown wheel, the contact pieces T, and the shoulder on which
the spring rests can be made in a separate piece of metal to the crown wheel, with
an insulated, in place of a metallic connection, between them.
The moveable handle L', is attached to a ring R, free to move in the case, thus
forming a lever whose fulcrum is situated at the axis of the case. In Figure 2, the
front portion of this ring is removed. The ring has attached to it a tooth C, shewn
in Fig. 4. A helical spring X, also shewn in Figure 4, is coiled round a wire bent
into a circular form and held at one extremity in a lug on the upper side of the
ring R; the other extremity of this wire works in a guide I, Figure 2, against

page_text: which also the spring X abuts. Starting from the position shewn in Figure 2,
when the handle L', is moved towards the fixed handle L, the spring X is compressed
and the tooth C engages in one of the teeth of the crown wheel, carrying it round
through the space of one of its teeth, and as there are only half as many contact
pieces T, as there are ratchet teeth, the block N will now be in a position inter-
mediate between two of the pieces T, and the circuit will be broken; on releasing L',
the spring returns it to its first position, the wheel and contacts remaining at rest.
The next time L', is moved towards L, one of the pieces T, is brought up to the
block N, and contact is again made. The ring R, fits loosely in the case and is
free to tilt, so as to enable the tooth C, to ride over the points of the ratchet teeth
during the return strokes. The upward set given to the spring X and to the wire
on which it is coiled, causes the ring to be depressed again as soon as the points of
the teeth are clear of one another, so that engagement is made for the next forward
stroke.
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 I
claim is,
In an electric switch, the use of two handles, susceptible of relative movement,
controlled by a spring or by the force of gravity, when suitably applied alternately
to open and close the contacts of an electric circuit, once in each to and fro move-
ment of the said handles, substantially as set forth.
Dated this 31st day of October 1892.
A. B. BLACKBURN.