Year: 1886

page_text: I, CHARLES BROWETT of Westfield, Coventry in the County of Warwick Gentleman,
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 & by the following
statement:-
My invention relates to an improved form of electrical switch by which an
electrical circuit may be opened or closed in a simple manner, by means of a cord,
which may be pulled by hand in the same way as an ordinary bell-pull, the
mechanism being so arranged that on the cord being pulled and released, the
circuit is closed, if previously opened, and opened if previously closed.
And in order that my invention may be better understood I have caused to be
appended hereunto one sheet of drawings marked with letters of reference indicating
like parts in the various figures.
Fig. 1 is a front elevation.
Fig. 2 is a plan of my improved electrical switch and Figs. 3, 4, and 5 and 6 are
modifications thereof.
The object in view may be attained by different devices as illustrated in the
annexed drawing. To this end and referring to Figs. 1 and 2 I secure on a base
plate or slab of non-conducting material two plates of brass or other good con-
ducting material, a & b, in such positions as to be insulated from each other.
To the plate a I attach by a binding screw a¹ or other device one end of the
wire c whose metallic continuity, it is desired to complete or interrupt, for the
purpose of allowing the current to flow or not. To the other plate b is attached
in a similar manner the other end of the wire c with which it is desired to make,
or break, contact.
On a stud or pin d fixed vertically in the metal plates a, is mounted, in such a
way as to be free to rotate, a toothed spur wheel f, and on another similar stud or
ping, fixed in the same plate a, is mounted a like wheel h in such a position, that
the teeth of the wheel gear with those of the other wheel h. On the latter, is
fixed, so as to rotate with it, a circular disc i of ivory or other suitable insulating
material, which is cut away across its diameter so as to receive a block of brass ỉ,
or other suitable metal, which block is in electrical contact with the terminal
plate a, by means of the brass stud g on which the wheel h and block / revolve,
the latter being so shaped on its edges as to form two metallic surfaces and leave
Price 871

page_text: two insulating surfaces, so that the insulating and conducting surfaces alternate in
a manner well known, in contact makers and breakers, the brass surfaces being left
a little prominent to insure a good contact when the circuit is closed.
Against the edge of this compound disc i, hereinafter called the make-and-break
disc, a rigid strip of brass o, or spring alone, is caused to press, by means of the
spring p, against the disc i thus bringing it into metallic contact with the second
insulated plate b, which strip o is conveniently secured thereto by a screw n.
To obtain a large surface contact, that end of the spring or strip of brass above-
mentioned, which presses against the make and break disc, may be curved to a
suitable radius, so as to embrace a portion of the disc instead of making a purely
tangential contact.
8
On one surface, (preferably the under), of each of the two toothed wheels are
fixed four studs r at equal distances from the centre of rotation and from each
other. A lever s free to vibrate on a pin t secured to the first insulated plate a is
arranged in such a position that one end of it, which is suitably shaped for the
purpose, engages with one of the studs r in the first toothed wheel, and is held in
contact therewith by a spring u and the other end of such lever beyond the
fulcrum pin is prolonged and arranged so that a cord v may be attached to it.
The two wheels f & h are geared together in such relative positions, that on
moving the said lever out of contact with one of the studs r on the first wheel f, it
engages with one of the studs r in the second wheel h, in such a way as to convert
the reciprocating motion of the lever. 8, when so caused to move, into an inter-
mittent rotary motion of both the wheels f and h, each in one direction, and if this
levers is made to vibrate through such an angle (determined by stops w fixed in
the plate a) as will cause each disc to rotate through one-eighth of a revolution for
each single vibration, then the effect of a complete motion of the lever 8, back and
forth will cause the make-and-break disc i, attached to the second wheel h, to
rotate through one quarter of a revolution.
The effect of this, is; that supposing one of the insulated portions of the make-
and break disc i to be in contact with the brass strip o, then when the lever 8 is
pulled down, by the cord attached to it, as mentioned, a partial rotation of the
make-and-break disc i, follows, sufficient to bring the next adjacent metallic
surface into contact with the strip and, on releasing the cord v, a further
rotation takes place by the reaction of the spring u, which obtains a very desi-
rable effect, namely, to slide a fresh portion of the same metallic surface into
contact, after contact is first made, so that any defect in the first contact due to
'sparking," with consequent corrosion of the surfaces, does not prejudice the
perfection of the metallic contact, through which the current has to flow, and,
by the rubbing of the surfaces together, both are kept clean. The next time that
the lever s is depressed & released, the spring u as before, causing it to return, the
make-and-break disc will perform another quarter of a revolution and will bring
one of its insulating surfaces into contact with the brass strip o thus interrupting
the current.
(
Thus the same motion, namely pulling and releasing the cord, at one time makes,
and at the next breaks the contact, so that this switch may be operated by any
one, by simply pulling & releasing the cord v either to, (say), light or extinguish
an electric lamp.
The whole mechanism is conveniently arranged in a circular box with a cover
so arranged as to protect the parts from dust, and yet be easily removed, and it
may readily be fixed to a wall by screws, the cord v hanging down so as to be
easily within reach.
The rotation of the make-and-break disc i, see Fig. 3, may also be obtained by
making the stud or boss of the spur wheelf the fulcrum of the lever 8. and pro-
viding the latter with a click y, which engages the teeth of the spur wheel f, and
in order to reduce the motion required to be given to the lever 8, the spur wheel f
is shown twice the size of the spur wheel h. The click y imparts motion to the
wheel only on the downward motion of the lever 8, the click y passing over

page_text: the teeth when the lever 8 is caused to return by the spring u as before, or a
ratchet wheels may be fixed in front or at the back of the make-and-break disc i,
and rotated by means of two levers 1 provided with studs 2 attached to the lever, s,
see Fig. 4, by which mechanism both the down and up motions of the lever s
impart motion to the ratchet wheel so that one quarter revolution of the make-
and-break disc i is ensured with a small angular motion of the lever s, or the
ratchet wheel z on the make-and-break disc i, may be rotated by a click y¹, fixed
to the lever 8, as illustrated in Fig. 5. A modification is shown in Fig. 6.
Having now described the nature of my said invention and in what manner
the same is to be performed I declare that what I claim is :-
First. In electrical switches, the mechanism described & illustrated by Figs. 1 & 2,
whereby an intermittent rotary motion is imparted to the make-and-break disc i
by the reciprocation of the cord lever 8, substantially as set forth.
Second. The combination of the cord lever 8, with the spur wheels f & h, the
latter being connected with the make & break disc i, substantially as described
& illustrated in Fig. 3.
Third. The combination of the cord lever 8, with a ratchet wheel z, having the
make-and-break disc i, connected thereto, either in the manner as illustrated by
Figs. 4 & 5 or Fig. 6, for the purpose specified.
Fourth. The combination of the cord lever (or its equivalent) with one or more
ratchet wheels & clicks so arranged as to actuate an electrical switch by depressing
& releasing the cord lever so that the same action by the operator at one time
breaks, and another makes the electrical circuit.