An Improved Automatic Electro-magnetic Switch..
Year: 1893

page_text: Date of Application, 5th July, 1893
Complete Specification Left, 5th Apr., 1894-Accepted, 5th July, 1894
PROVISIONAL SPECIFICATION.
An Improved Automatic Electro-magnetic Switch..
I, JAMES HARDIE MCLEAN, Electrician and Engineer, 45 Broad Street,
Oxford, do hereby declare the nature of this invention to be as follows:-
My invention is devised with a view to switch off the current from electric are
lamps used in the streets of a town for lighting purposes at any given time.
In accordance with my invention I provide an electric switch actuated by a lever
which latter is connected to an iron armature of an electro-magnet.
I also employ an electric alarm clock which makes electric contact at any given
time thus sending a current (derived from the electric service mains which feeds
the arc lamps) which causes the electro magnet to become strongly magnetized
and so pulling down the iron armature and with it the lever thus actuating the
switch and so cutting off the current from and extinguishing the lamps. Said
clock is so connected that immediately the lamps are extinguished the current
passing through the electro magnet and clock is also cut off, this prevents any
possibility of sparking at the clock contacts, consequently they cannot get out of
order.
It will be seen that by the use of the switch as above described currents can be
cut off, automatically at any given time without having to send any one to do it
thus making it impossible to waste current as when leaving the operation to he
performed by anyone who might forget.
Said switch will also be suitable for circuits when power is being used say for
instance in electro-motors for driving purposes and the like.
Dated this 30th day of June 1893
JAMES
STEVENSON,
Gray's Inn Chambers, 20, High Holborn, London, W.C.,
Agent for Applicant.
COMPLETE SPECIFICATION.
An Improved Automatic Electro-magnetic Switch.
1, JAMES HARDIE MULEAN of 45 Broad Street, Oxford, Electrician and
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:-
My invention is devised with a view to switch off the current from electric arc
lamps, used in the streets of towns for lighting purposes, at any given time.
And in order that my invention may be more fully understood, I have appended
the accompanying sheet of drawings diagrammatically arranged, in which Figure 1 is
a front view of my improved switch and Figure 2 an end view of same.
The improved automatic electro magnetic switching arrangement consists of a
switch which may be either single or double pole, an electro magnet which
makes the switch break contact, a solenoid which causes the switch to make
contact, and a 24 hour electric alarm clock fitted with two separate alarms,
which make contact at two separate points; or, two ordinary 12 hour electric
alarm clocks.
In Figure 1 which shows a front view of my improved automatic electro
magnetic switch, the armature a of the electro magnets bb is connected to the
switch-beam c, which latter is composed of strong insulating material such as

page_text: ebonite, box wood or the like, by means of the connecting rod d. Said connecting
rod d is provided with a slotted hole e which terminates at the top end with a small
recess, into which the pin of the switch beam c fits, when the switch is on, (as
shewn in Figure 1). ggare two fixed slides along which the armature a and the
switch beam c travel, when the switch is in motion.
h is a base, also made of some insulating material such as ebonite, box wood or
the like, into which the top ends of the slides g g above referred to are firmly
secured. ii are two connecting rods which are free to move through the base
plate hand are firmly screwed into the switch beam c at one end, and the cross
beam at the other end. Said cross beam k has screwed into its centre the soft
iron core of the solenoid m. Situated at the top end of the iron core is a spiral
spring n and a tightening screw o, which are employed for balancing the weight of
the core.
P 9 represent two 12 hour electric alarm clocks, but as before stated, one 24 hour
electric alarm clock fitted with two separate alarms will suffice.
rr indicate two are lamps connected in series across the supply mains x.
s is a small arm or link secured loosely to one of the guide rods g at one end, and
to the connecting rod d at the other end.
P
The working of my improved automatic electro magnetic switch when adopted
for switching off the current from electric arc lamps; and, for switching same on
again, at any given time, is as follows;-viz. :-Suppose the time has arrived when
the switch must be turned off, the alarm in clock will make contact thus causing
the current to pass through the electro magnets bb, when the armature a is drawn
down swiftly onto the magnetic cores. It will be then seen that the switch
beam has also been drawn down until it just breaks contact at the terminals tt;
and, at the same time the connecting rod d, has been forced parallel with the guide
rods gg, by means of the arm or link s. The vertically slotted hole e above referred
to is then brought directly under the pin f, whilst the spring v, which is in com-
pression, forces the switch beam c, away rapidly from the terminals tt, thus causing
the switch to make a very quick break.
The switch is now off, and it will also be seen that the cross bar k and the
solenoid core l, have also been drawn down by means of the connecting rods i i
which are firmly secured into the switch beam c, and which also pass through
the base plate h. To follow the working of my improved switch, suppose the time
has arrived for switching on the current the alarm clock q will make contact,
sending a current round the coil on the solenoid m, which will begin to draw up
the core l, and will also begin to raise the switch beam c; the pin simply moving
along the slot e; when it has reached the top of said slot, it will begin to draw
up the armature a and compress the spring ; at the same time, the connecting
rod d is drawn over by the arm or link s, and the pin f travels into the recess formed
at the top end of the slotted hole e.
The switch will be on when the core has been drawn up as far as it will go.
The improved switch as above described can also be used with advantage for
circuits when power is being used, say for instance, in electro motors for driving
purposes and the like.
The current for actuating the switch can be derived from the service mains
which supply the current to the circuit which the switch controls; or, the switch
may be actuated by means of a primary or secondary battery. The wiring of
the coils can be such, that the switch can be placed on circuits of almost any
voltage.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I wish it to be
understood that I make no claim in respect merely of electrically actuated clocks
and the employment of solenoids or electro magnets, but what I claim is :-
First. The automatic electro magnetic switching combination device substantially
as herein described and shewn.

page_text: Second. In the switching device referred to in the preceding claim the employ-
ment of a connecting rod d having a vertical slotted hole e as and for the purposes
berein set forth.
Dated this 4th day of April 1894.
JAMES
STEVENSON,
1, Furnival Street, Holborn, London, E.C., Agent for Applicant.