Improvements in or relating to Electrical Contact-breakers.
Year: 1899

page_text: PROVISIONAL SPECIFICATION,
Improvements in or relating to Electrical Contact-breakers.
I, GEORGE BOWRON, of 57, Edgware Road, in the County of Middlesex, Elec-
trician, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in electrical contact-breakers, and is
especially applicable to contact-breakers for use with induction coils.
Contact-breakers as hitherto made generally comprise an armature of iron,
mounted upon the end of a spring, and are all more or less open to the objection
that the motion of the armature is retarded and a portion of its energy absorbed
by the action of the spring upon which it is mounted. This results in the
break being slower than it would otherwise be, a serious disadvantage in most
cases.
In contact-breakers constructed according to this invention the armature is
not mounted rigidly upon a spring, but is so arranged that during at any rate
a portion of its stroi, its progress is free and unimpeded, except for the small
amount of friction which necessarily exists between it and its support.
This can be accomplished in various ways, for instance the armature may
be arranged to slide freely in guides, such guides being, if desired, furnished
with friction rollers or equivalent devices, or again it may be supported upon
an arm hinged or pivotted to oscillate freely in the desired plane.
It is preferred to cushion the armature at each end of its stroke; this may
be accomplished by the use of springs, which may be attached to the armature
and operate in conjunction with rigid adjustable stops, or such springs may be
stationary and may be compressed by the impact of the armature at the latter
portions of its travel. The springs in recovering their normal form, give back
to the armature some of the energy stored up in them, thus quickening the
next stroke. They are preferably made adjustable, so that, if desired, an initial
compression may be given to them, this being found to be a great advantage
in working one contact-breaker under varying electrical conditions. In addition
to, or instead of, the springs, dash-pots or similar devices may be used, or a
single spring may be employed in place of two separate ones. The return of
the armature may, if desired, be brought about by gravity, or by an auxiliary
electro-magnet.
In one form of contact-breaker according to this invention a retaining device
or catch is employed, so that the armature is prevented from moving towards
the main electro-magnet until the latter is fully magnetised.
It is preferred to mount the contacts independently of the armature and its
mountings, for example, one contact may be rigidly, though adjustably, carried
on a bracket or standard, and the other may be mounted upon a spring or
hinged arm, so arranged that the contacts normally touch one another. A catch,
or equivalent, upon, or attached to, the armature engages with the contact
spring or arm at a certain point towards the end of the forward movement of
the armature, and thus the contact is suddenly broken, such break being

page_text: arranged to take place just before the point at which the cushioning spring
comes into action. It is sometimes preferred to place the movable contact upon
the longer arm of a lever, the shorter arm of which is acted upon directly or
indirectly by the moving armature; a rapid and large break is thus obtained.
When the movable contact is carried upon a spring, this spring naturally assists
the return movement of the armature, but it is preferred to make this spring
merely supplemental to the other spring situated at the end of the armature
stroke. The return of the movable contact into touch with the fixed contact
may be brought about by means of a spring or by gravity, or by a separate
electro-magnet. Both the contacts may if desired be movable, and the movement
of the armature may displace both of them.
Although in the above description it has been assumed that platinum or
similar contacts are employed, it is of course obvious that this invention is
equally applicable to mercury contact-breakers, or to any form of contact-breaker
in which the contacts are mechanically separated.
Dated this 1st day of March 1899.
Improvements in or relating to Electrical Contact-breakers.
I, GEORGE BOWRON, of 57, Edgware Road, in the County of Middlesex, Elec-
trician, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described in and by the following
the following statement:
This invention relates to improvements in electrical contact-breakers, and is
especially applicable to contact-breakers for use with induction coils.
Contact-breakers as hitherto made generally comprise an armature of iron,
mounted upon the end of a spring, and are all more or less open to the objection
that the motion of the armature is retarded and a portion of its energy absorbed
by the action of the spring upon which it is mounted. This results in the
break being slower than it would otherwise be, a serious disadvantage in most
cases.
In contact-breakers constructed according to this invention the armature is
not mounted rigidly upon a spring. but is so arranged that during at any rate
a portion of its stroke, its progress is free and unimpeded, except for the small
amount of friction which necessarily exists between it and its support.
This can be accomplished in various ways, for instance the armature may
be arranged to slide freely in guides, such guides being, if desired, furnished
with friction rollers or equivalent devices, or again it may be supported upon
an arm hinged or pivotted to oscillate freely in the desired plane.
It is preferred to cushion the armature at each end of its stroke; this may
be accomplished by the use of springs, which may be attached to the armature
and operate in conjunction with rigid adjustable stops, or such springs may be
stationary and may be compressed by the impact of the armature at the latter
portions of its travel. The springs in recovering their normal form give back
to the armature some of the energy stored up in them, thus quickening the
next stroke. They are preferably made adjustable, so that, if desired, an initial
compression may be given to them, this being found to be a great advantage
in working one contact-breaker under varying electrical conditions. In addition

page_text: to, or instead of, the springs, dash-pots or similar devices may be used, or a
single spring may be employed in place of two separate ones." The return of
the armature may, if desired, be brought about by gravity, or by an auxiliary
electro-magnet.
It is preferred to mount the contacts independently of the armature and its
mountings, for example, one contact may be rigidly, though adjustably, carried
on a bracket or standard, and the other may be mounted upon a spring or
hinged arm, so arranged that the contacts normally touch one another. A catch,
or equivalent, upon, or attached to, the armature engages with the contact
spring or arm at a certain point towards the end of the forward movement of
the armature, and thus the contact is suddenly broken, such break being
arranged to take place just before the point at which the cushioning spring
comes into action. It is sometimes preferred to place the movable contact upon
the longer arm of a lever, the shorter arm of which is acted upon directly or
indirectly by the moving armature; a rapid and large break is thus obtained.
When the movable contact is carried upon a spring, this spring naturally assists
the return movement of the armature, but it is preferred to make this spring
merely supplemental to the other spring situated at the end of the armature
stroke. The return of the movable contact into touch with the fixed contact
may be brought about by means of a spring or by gravity, or by a separate
electro-magnet. Both the contacts may if desired be movable, and the movement
of the armature may displace both of them.
Although in the above description it has been assumed that platinum or
similar contacts are employed, it is of course obvious that this invention is
equally applicable to mercury contact-breakers, or to any form of contact-breaker
in which the contacts are mechanically separated.
In the accompanying drawings
Figure 1 is a perspective view of one construction of contact-breaker according
to this invention, and
Figures 2 and 3. show in perspective portions of other constructions of con-
tact-breakers also according to this invention.
Like letters indicate like parts throughout the drawings.
A is a base upon which the various parts of the contact-breaker are mounted
and may be either separate from or part of the base supporting an induction
coil B. C is an armature preferably of soft iron, carried upon an arm C¹ pivotally
mounted in bearings C2 attached to the base A. The armature C is fitted with
a screwed rod 03 upon which a nut C works, this nut C4 forming an adjustable
catch which, when the contact-breaker is in operation, engages with the end of
a spring D carrying a contact E. The spring D is secured at its base by screws DI
and a second spring F is placed near it, the distance between the two springs
being capable of regulation by means of a screwed rod FI which can be screwed
in or out of a pillar F2 supporting it. The rod F¹ is provided with a milled head
of insulating material F3 and passes through clearing holes in a pillar G and
in the contact-carrying spring D, being secured to the spring F by means of
a flange upon an insulating sleeve F. This insulating sleeve F is kept in
position upon the rod F by means of a nut Fº.
The pillar G is fitted with a screw H having a milled head H' and a lock-nut H².
This screw carries a second contact El arranged in line with the movable contact E.
At the upper part of the pillar G another screw is fitted, which is in line
with the screwed rod C³ of the armature when that rod is horizontal. The
screw J is provided with a milled head J¹ and a lock-nut J2 and its point, which
is reduced in diameter, carries a spiral spring J3 which acts as a cushion for
the armature C at the end of its return stroke. The end of the spring J³ is
closed by a cap of insulating material J4 against which the end of the screwed
rod C3 abuts on the return stroke of the armature. In order that the spring Ja
may, if desired, be given an initial compression the screw J is made hollow and
a small rod J is passed through it, the inner end of the rod being fastened to

page_text: the insulating cap J4, while the other end is screwed and provided with a nut Je
which bears against the head J¹. By turning the nut J6 the rod J5 may be drawn
outwards and the spring J3 compressed. By screwing the screw J in or out of
the pillar G, the length of stroke of the armature C may be regulated if desired
while the contact-breaker is in operation.
The contacts E and E¹ are connected through the spring D and pillar G res-
pectively to a battery or other source of electrical energy, a switch and the
induction coil B, but these connections are not shown as they form no part of
the present invention, similar arrangements being in common use.
The operation of the apparatus shown in Figure 1 is as follows:-The armature,
which is arranged, as is usual in apparatus of the kind, in juxta-position to
the core B of the induction coil B, is attracted to that core when the coil is
energized, and, being pivotted freely at C2, at once commences its forward stroke.
During that stroke the adjustable catch C comes into contact with the top of
the spring D and moves that spring forward, thus quickly breaking connection
between the contacts E and E¹. The impetus of the armature C carries it forward
against the action of the springs D and F, which thus act as cushioning springs
for the armature at the end of its forward stroke. The springs D and F then
return to their normal position carrying the armature C with them, and the
spring J3 acts as a cushioning spring for the latter part of the return stroke.
Connection being re-established between the contacts E and E¹, the armature is
again attracted and so the cycle is repeated.
It is to be understood that the spring F, the function of which is to act as
a cushioning spring for the end of the forward stroke, may, if desired, be placed
so that it acts directly upon the armature C or its support. Or again, this
spring may be in the form of a spiral and not a flat spring as illustrated.
Sometimes electro-magnets are employed to assist the forward or return strokes
of the armature. In Figure 1 a coil K is diagrammatically shown surrounding
the screw J. This screw J, together with the rod C3 and nut C would. in his
case, be made of iron or other magnetic material, and if a current be caused to
pass round the coil K, the screw Jis magnetized and attracts the armature C
and its appurtenances, thus accelerating the return stroke. The armature itself
may be magnetized as, for example, by a coil L also shown diagrammatically in
Figure 1. This coil L is placed round the supporting arm C¹ which would in this
case be of magnetic material and, according to the polarity of the armature either
the forward or return stroke may be accelerated. The currents in these magne-
tizing coils K and L may, in each case, be either continuous or may act only
during the motion of the armature in one direction, being broken-say by the
movement of the armature itself-during the other stroke.
Figure 2 illustrates a form of contact-breaker according to this invention suit-
able for placing upon existing apparatus. In this construction the armature_C
is carried by, and capable of sliding freely upon, a pin D2 mounted upon the
contact spring 1). The motion of the armature C is limited at one end of the
pin by a nut D³, and a cushioning spring J is placed between the other end of
the armature and the contact spring D.
In Figure 3 an arrangement is shown in which a contact-breaker according to
this invention is used in conjunction with a mercury contact device:-The arm-
ature and its parts are similar to those above described with reference to
Figure 1, but, instead of the spring D and the contacts E and E¹ a bell-crank
lever M is provided pivotted as at M¹ to a block M² secured to the base A. The
lower end of this lever M carries an adjustable contact screw M³ which dips into
a mercury cup N. A cushioning spring F is placed behind the upper portion of
the lever and acts in a similar way to the corresponding spring in the con-
struction shown in Figure 1, being adjustable by means of a screw F working
in the block M2. The return of the bell-crank lever M to its normal position
is brought about by means of a spring M, one end of which is secured to the
block M while the other bears against a pin M³ in the lever M,

page_text: When, in this specification, the armature is mentioned as not being "spring-
controlled" it is to be understood that the armature is not rigidly attached to
a spring upon which it vibrates in the manner wellknown in contact-breakers,
and that the cushioning springs, such as for example J³ and F are not included in
this term, although they may, in a sense, be said to exercise control over the
stroke of the armature.
It is to be. understood that various alterations may be made in the construc-
tion of the improved contact-breakers without departing from the spirit of this
invention; for example a separate electro-magnet may be used to operate the
armature instead of employing the core B₁ of the induction coil for that
purpose. In this case it is convenient to use a horse-shoe electro-magnet and of
course to shape the armature so as to act in conjunction with the two poles.
Again, the armature may be suspended from, instead of being supported upon,
a pivot.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. A contact-breaker having a reciprocating armature which for the whole or
a portion of its stroke is not "spring-controlled."
2. In a contact-breaker the combination with a contact-carrying device of
a freely moving reciprocating armature which is not rigidly attached thereto.
In a contact-breaker the combination substantially as described with a
freely moving reciprocating armature of one or more cushioning springs.
4. In a contact-breaker the combination with a reciprocating armature moving
freely about a pivot of an adjustable catch which engages with a contact-carry-
ing device after the armature has commenced its forward stroke.
5. In a contact-breaker the combination with a spring such as 1) carrying
a contact of another spring adjustable relatively thereto and causing in conjunc-
tion therewith the return stroke of the armature.
6. In a contact-breaker of the kind described the employment of an electro-
magnet to assist the forward or return stroke of the armature.
7. In a contact-breaker the combination with a contact-spring 1 carrying a
pin 12 of an armature C free to slide upon the pin and cushioned by a spring J³
substantially as described.
8. In a contact-breaker the combination substantially as described with a
freely moving reciprocating armature of a mercury contact device.
9. The complete contact-breaker substantially as described and illustrated in
Figure 1 of the accompanying drawings.
Dated this 29th day of November 1899.
GEORGE BOWRON.
Boult and Wade,
Agents for the Applicant.