Improvements in Circuit Making and Interrupting Devices for Electric Bells and other Purposes.
Year: 1888

page_text: Date of Application, 21st Sept., 1888
Complete Specification Left, 21st June, 1889-Accepted, 27th July, 1889
TROYIDIONAL DIBUIFICATION.
Improvements in Circuit Making and Interrupting Devices for
Electric Bells and other Purposes.
I WILLIAM SNELGROVE of Bankwood, Church Road, Moseley in the County of
Worcestershire Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates more particularly to circuit making and interrupting devices
for electric bells but it is also applicable to electro-motors and other purposes where
an electric current is required to be interrupted at definite intervals.
In most electric bells as at present constructed the bell receives very short and
feeble strokes from the hammer in very rapid succession and the effect is more that
of a confused chatter rather than a series of separate strokes, this defect is due to
the action of the current interrupter; the object of my invention is to arrange the
current interruptor in such a way that the successive strokes may be delivered at
longer intervals and thus allow time for the bell to vibrate into sound and avoid
checking or varying its vibration by succeeding strokes.
In its application to electric bells one arrangement of my invention is as follows:-
A bell is mounted in any usual manner and it is struck by a hammer at the end of
a lever; the acting stroke is given by an electro-magnet attracting an armature
upon the lever and the hammer is taken away from the bell by its weight or by a
spring. The making and interrupting of the electric circuit is controlled by a second
lever which is actuated by the hammer lever, but is moved only when near the
termination of the hammer stroke in either direction; the second lever carries or
actuates a cam which moves a spring and causes contact to be made or interrupted.
The current to the electro-magnet passes through the spring and when it is pressing
against the electric contact piece the current passes and the magnet is excited; when
it is raised from the contact pieco the current is interrupted.
When the current excites the electro-magnet, the armature is attracted and the bell
receives a stroke.
In ordinary electric bells immediately the hammer begins to move the current is
interrupted; in this bell the current continues until the stroke is nearly completed
and the second lever is moved by the hammer lever, only when it approaches the
end of its stroke.
This is accomplished by connecting the two levers by a fork, slot and pin or
equivalent contrivances so that any desired movement may take place independently.
In the same way when the hammer moves away from the bell the circuit is not at
once made but the hammer is free to move nearly the full distance from the bell,
before the second lever is moved causing the current to pass and the electro-magnet
to be excited again.
▸
The bell may of course be arranged for the reverse action that is the acting stroke
to be given by gravity or spring and the hammer taken away by the electro-magnetic
action in which case the same apparatus is used but contacts rearranged.
By proportioning the length of the levers, the distance apart of the stops and
therefore the amount of independent movement, a considerable variation of the rate
of striking may be arranged.
I
may also arrange the current to pass by the second lever instead of the spring
and secure good contact by a spring thrusting the lever against a contact piece or by
constructing the lever of iron and making the contact piece a magnet so causing it
to adhere by magnetic attraction. Magnetism or friction may also be used to hold
the second lever in whatever position the first lever or hammer leaves it.
A forked end may also move a spring directly, which carries the current and a

page_text: permanent magnet or electro-magnet may keep the spring off the contact until it is
moved away by the fork, to be returned by the fork again by the next stroke.
Instead of making the contact by pressing a spring against a contact piece and inter-
rupting by separating, I may use other forms of contacts such as a metal slide or disc,
having embedded in it a piece of nonconducting material, this slide or disc is moved
by the hammer lever and a spring or lever pressing against it alternately rests upon
the non conductor and the metal and so alternately interrupts and passes the
current.
When it is desirable to have the power of adjusting the strokes to different rates
while the bell is acting I use another device; it consists of an inclined metal tube
made in two parts in line with each other but insulated; the lower portion is short
and is partly closed at the end to prevent a metallic ball, which moves freely in the
tube, from falling out. When the ball is at the lower end of the tube it bridges the
space between the two portions and a current can then pass between them; when
the ball moves up the tube the two portions are electrically separated and the current
is interrupted.
The hammer lever is arranged so that as the bell receives its stroke the ball is also
struck and propelled up the tube, this interrupts; and although the hammer moves
away from the bell the electro-magnet cannot again be excited until the ball rolls
down and makes contact, so that an interval occurs between the strokes depending
upon the time taken by the ball to roll down. The tube may be constructed of soft
iron and made an electro-magnet so that the first effect of contact by the ball is to
make the tube magnetic and cause the ball to adhere strongly and give good
contact.
If the inclination of the tube be altered then the time of rolling down is altered and
consequently the length of pause between the strokes.
Suitable stops are provided to prevent the ball from being expelled from the tube
by too powerful a stroke. Instead of a discontinuous tube and ball a similar plate
and roller may be used or the hammer lever may actuate a pendulum with roller,
ball or similar contact making device to secure periodic control of the current.
The application of my invention to reciprocating or rotary electro-motors or any
purpose requiring periodic interruption of current is precisely similar to its application
to bells.
The bell and electrical devices may be arranged in any convenient manner but I
sometimes prefer to arrange the electro-magnet and hammer within the bell itself,
the bell being constructed so as to swing clear of the mechanism when desired. The
pillar supporting the bell may also be utilized as the core of the electro magnet in
which case it will be constructed of soft iron.
Dated this 20th day of September 1888
MARKS & CLERK,
Agents for Applicant.
COMPLETE SPECIFICATION.
Improvements in Circuit Making and Interrupting Devices for
Electric Bells and other Purposes.
I WILLIAM SNELGROVE of "The Nest," Kings Norton in the County of Worcester,
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 relates more particularly to circuit making and interrupting devices
for electric bells but it is also applicable to electro motors and other purposes where
an electric current is required to be interrupted at definite intervals.
In most electric bells as at present constructed the bell receives very short and
feeble strokes from the hammer in very rapid succession and the effect is rather that
of a confused chatter rather than a series of separate strokes, this defect is due to the

page_text: action of the current interrupter; the object of my invention is to arrange the current.
interrupter in such a way that the successive strokes may be delivered at longer
intervals and thus allow time for the bell to vibrate into sound and avoid checking
or varying its vibration by succeeding strokes.
In its application to electric bells one arrangement of my invention is as follows:-
A bell is mounted in any usual manner and it is struck by a hammer at the end of a
lever; the acting stroke is given by an electro-magnet attracting an armature upon
the lever and the hammer is taken away from the bell by its weight or by a spring-
The making and interrupting of the electric circuit is controlled by a second lever
which is actuated by the hammer lever, but is moved only when near the termination
of the hammer stroke in either direction; the second lever carries or actuates a cam
which moves a spring and causes contact to be made or interrupted-The current to
the electro magnet passes through the spring and when it is pressing against the
electric contact piece the current passes and the magnet is excited; when it is raised
from the contact piece the current is interrupted-When the current excites the
electro magnet, the armature is attracted and the bell receives a stroke.
In ordinary electric bells immediately the hammer begins to move the current is
interrupted in this bell the current continues until the stroke is nearly completed
and the second lever is moved by the hammer lever only when it approaches the end
of its stroke.
This is accomplished by connecting the two levers by a fork, slot and pin or
equivalent contrivances so that any desired movement may take place independently-
In the same way when the hammer moves away from the bell the circuit is not at
once made but the hammer is free to move nearly the full distance from the bell,
before the second lever is moved causing the current to pass and the electro-magnet
to be excited again.
The bell may of course be arranged for the reverse action that is the acting stroke
to be given by gravity or spring and the hammer taken away by the electro-magnetic
action in which case the same apparatus is used but contacts re-arranged.
By proportioning the length of the levers the distance apart of the stops and therefore
the amount of independent movement, a considerable variation of the rate of striking
may he arranged.
may also arrange the current to pass by the second lever, instead of the spring
and secure good contact by a spring thrusting the lever against a contact piece.
Magnetism or friction may be used to hold the second lever in whatever position the
first lever or hammer leaves it.
Instead of making the contact by pressing a spring against a contact piece and
interrupting by separating, I may use other forms of contacts such as a metal slide or
disc, having embedded in it a piece of non-conducting material, this slide or disc is
moved by the hammer lever and a spring or lever pressing against it alternately
interrupts and passes the current. When it is desirable to have the power of
adjusting the strokes to different rates while the bell or other apparatus is acting I
use another device, it consists of an inclined metal tube made in two parts in line
with each other but insulated; the lower portion is short and is partly closed at the
end to prevent a metallic ball, which moves freely in the tube from falling out. When
the ball is at the lower end of the tube it bridges the space between the two portions
and a current can then pass between them; when the ball moves up the tube the two
portions are electrically separated and the current is interrupted. Instead of the
divided tube in which the ball itself acts as the contact maker, the ball may be made
to strike and operate contact levers.
The hammer lever is arranged so that as the bell receives its stroke the ball is
also struck and propelled up the tube, this interrupts and although the hammer
moves away from the ball the electro-magnet cannot again be excited until the ball
rolls down and makes contact, so that an interval occurs between the strokes
depending upon the time taken by the ball to roll down.
If the inclination of the tube be altered then the time of rolling down is altered and
consequently the length of pause between the strokes.

page_text: The application of my invention, to reciprocating or rotary electro motors or any
purpose requiring periodic interruption of current is precisely similar to its application
to bells.
In another arrangement of my invention I obtain the increased length of attractive
stroke without the use of a forked lever or its equivalent. In this case if construct
the electro-magnet or coil to be moveable or to vibrate on a centre while: the armature
is fixed and the hammer lever is attached to the magnet. The electro-magnet is so
constructed that at the same moment that it is attracted and moves towards the fixed
armature, it also attracts and carries with it the flexible contact spring or lever
supplying the current. This contact lever is only released just before the hammer
strikes the bell, it then springs back to the original position and the electro magnet
follows it and makes a fresh contact and circuit on reaching it.
In order that my invention may be fully understood and readily carried into
effect I append hereunto two sheets of explanatory drawings which I will now
describe.
Figures 1 to 7 on sheets 1 and 2 refer to various methods of carrying my invention
into effect.
Figure 1 sheet 1 shows the arrangement first described in which the electric circuit
is interrupted or made by a forked lever and a spring.
The bammer A is arranged to strike the bell B and it carries an armature (which
is attracted at a proper time by the electro-magnet D-The current from the battery
passes to and from the electro magnet by the wires E, F, and through a spring Ġ
mounted on an insulating block H. H, which also carries the forked lever I pivotted
at L. In one position of the forked lever the spring G presses against the contact
screw. J and the circuit is made and allows the current to pass from the battery
through the electro-magnet D; in another position the spring G is lifted off the
screw J and the circuit is interrupted. This is done by the cam shaped portion of
the lever I which is marked K.
The action is as follows: When the bell is out of action the hammer lever A is
withdrawn from it by the spring M and the end N working between the fork of the
lever strikes the lower screw O which moves to its lowest extreme position, the
cam K is so shaped that in this position the spring G presses against the contact
screw J and the circuit is complete-If the current be now passed by pressing the
ringing button the electro-magnet D becomes excited and attracts the armature C.
The hammer lever A. therefore moves: downwards and the bell receives a stroke; just
before the bell is struck the end N comes in contact with the screw,P and the forked
lever I is moved to .its upper extreme position while the cam K attached or forming
part of it lifts the spring G from the contact screw J and so breaks the circuit-The
dotted lines show the upper position of the lever I and the spring G lifted off the
contact screw. The electro magnet then ceases to attract and the spring M lifts
the hammer from, the bell and at the extreme of its stroke upwards the end N moving
down strikes the screw O and returns the forked lever. I to its lower position in which
the spring G makes contact with J and. the current passes again. The hammer thus
strikes again and continues repeating the operations described so long as current is
supplied to the bell.--Figure 2 sheet I shows another arrangement of my invention in
which the current passes through the second lever instead of through a separate
spring For similar parts the same letters are used as in Figure 1.. In this case the
hammer lever A is arranged differently and is so pivotted. that, the armature C moves
in the same direction as the hammer; the bell is not shown but the spring Macts as
in the first method-The forked. lever I is pivotted at Land one end of it makes
contact with the contact screw J in the insulated piece H:
When in one position as shown in dotted lines the circuit is interrupted, and the
lever A is free to return under the influence of the spring. M:. The spring Qis
arranged to press upon the shaped end of the lever I in such manner that the lever
remains in the positions in which the end. N of the hammer: lever Arleaves it and
when touching the contact screw J.the shape of the end in contact with the spring Q
is arranged that pressure is applied to keep the lever against J... The current passes

page_text: by the wires E and F through the electro magnet D by way of the lever I which may
be in metallic contact with a plate or electrically connected in any other way to the
wire R.
By these means the forked lever I is moved at each end of the stroke of the hammer
lever A and the circuit remains open or closed throughout nearly the whole stroke in
either direction.
Figures 3, 4, 5 and 6 Sheet 2 show one arrangement of my invention where I uso
sliding contact and interrupt the circuit by means of a non-conducting piece let into
the moving surface. In this case I use a modified arrangement of armature and I
connect it to the hammer lever A differently from the methods I have herein before
described.
One end of the armature C is pivotted to one end of the lever A at a and the other
end to a lever at c; the centres upon which these levers work are so placed that
when the hammer lever moves, the armature C moves to and from the electro magnet
poles S. T. and preserves parallelism with their surfaces, and by so doing a more
powerful attraction is obtained than when each point of the armature surface is at
varying distances from the poles as is the case when an armature is attached to an
ordinary lever.
Figure 4 is a plan of the armature showing the pins a and b upon which it works..
The forked lever I Figures 3 and 6 is moved to and fro by a projection d from the
armature Cit pivots at L and is in metallic contact with the plate U. The spring G
is insulated from the plate U and is in communication with one of the poles of the
battery, it presses against the segmental end of the lever I which has at one portion a
nonconducting piece e let into its surface. When the lever is in one position the
spring G presses against the metal, in the other position it presses against the
nonconducting piece and so the circuit is completed or interrupted-As shown in
figure 3 the hammer has just completed its movement away from the bell, in this
instance by the action of gravity and the projection d has moved the forked lever I
and caused the spring G to touch the metallic part and the armaturo C will move
towards the electro magnet poles S. T. When it comes very near them and the
hammer is about to strike the bell, the projection d moves the lever I in the direction
shown by the arrows and the spring G presses upon the insulating pieco e thereby
interrupts the circuit and allows the hammer to fall away again. Figure 5 is an end
elevation of the complete bell and Figure 6 is a plan in which the hammer is shown
striking the bell and the forked lever I is in the position of interrupting the circuit.
The stops f. g. are for limiting the movement of the forked lever so that the
momentum it acquires by the blow from d may not carry it too far. Instead of the
forked lever I a slide may be used having an insulating piece and moved to and fro
by the projection d.
Figure 7 Sheet 2 shows the arrangement of circuit making and interrupting device
where I use a ball propelled up an inclined tube by the stroke of the hammer lever to
make and interrupt the circuit and where the frequency and interval between the
strokes is controlled by the time taken by the ball to return from the higher end of
the tube. The hammer lever A strikes a contact lever I and propels a ball up a
tube K, the lever I is kopt in position away from the contact screw J by the spring G
until the ball returns again and knocks it away to its other extreme position
thereby making the circuit. There it remains until the hammer lever strikes it and
breaks contact again.
The intervals between the strokes may be varied by varying the inclination of
the tube K which can be readily done even while the bell is ringing.
At Figure 2 Sheet 1 another modification is shown in which the electro-magnet D
moves with the hammer lever A and the Armature C remains fixed. The current passes
from the wire F by the spring G to the pole piece W of the electro-magnet D when
latter is in contact with G; and when the current passes D is attracted to C but the
spring G adheres to W and follows its movement till it strikes the stop X when it is
knocked off and springs back to adjusting screw J and the current is interrupted
just as the hammer is about to strike the bell. The electro magnet D then returns

page_text: to the spring G either by its own weight or by a spring and again makes the circuit.
In this manner the circuit is made or interrupted just before the end of the stroke
in either direction. The normal position of spring G is pressing against screw J.
In the drawing the electro magnet D has just reached the armature and the hammer
is striking the bell, it will now return by gravity until the pole piece W strikes
against the spring G and makes a fresh contact.
In the various methods I have described the action of the armature and electro-
magnet may be reversed and the bell may receive its stroke by the action of gravity
or a spring while the electro-magnet pulls the hammer away preparatory to a new
stroke, and instead of a forked lever the fork may be upon the armature, or two pins
may be used.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner same is to be performed I declare that what I
claim is
1. The combination of parts constituting an electric bell as herein before described
with reference to:figures 1 and 2 of the accompanying drawings.
2. The combination of parts constituting an electric bell as hereinbefore described
with reference to figures 3 to 6 of the accompanying drawings.
3. The circuit making and interrupting device having a ball propelled up a tube
by a stroke of hammer or lever in bells, electro motors or other electro magnetic
apparatus with reference to Figure 7 of the accompanying drawings.
4. In an electric bell the combination of the armature moving parallel to any given
poles, such as C figure 3 substantially as herein set forth.
5. In an electric bell the combination of a vibrating electro magnet or coil and a
fixed armature arranged so that the magnet not only is attracted to the armature but
at the same time attracts and carries with it for any desired distance its contact lever
or spring which conveys the current as herein set forth.
Dated this 18th day of June 1889.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for Applicant.