Improvements relating to Electric Arc Lamps.
Year: 1896

page_text: Date of Application, 1st Dec., 1896
Complete Specification Left, 1st Oct., 1897-Accepted 1st Feb., 1898
PROVISIONAL SPECIFICATION.
Improvements relating to Electric Arc Lamps.
We, WILLIAM REGINALD RIDINGS, of Fairview, Bristol Road, Bournbrook, in
the County of Worcester, Engineer, and JoHN HENRY CRAWFORD, of 7, Broad
Street Avenue, in the City of London, Gentleman, do hereby declare the nature
of this invention to be as follows:-
Our invention relates to the brake mechanism of electric arc lamps, and more
especially to brake mechanism of that kind or class described in the Specification
accompanying previous Letters Patent granted to one of us conjointly with
George Frederick Bull, and Llewellyn Burbank Codd, No. 7788 of 1895.
In the said former Specification a brake mechanism is described wherein a
core or plunger is suspended at each end of a pivoted beam or lever, which cores
or plungers are excited respectively by a coil or solenoid wound in series, and by
a coil or solenoid wound in shunt, so as to effect, through a series of levers, the
disengagement of a pad or roller from a drum or friction wheel or its equivalent,
and so to adjust the arc. To prevent the above mentioned pivoted beam or lever
from being operated too abruptly under the action of the core or plunger and
series coil or solenoid, a dash pot is provided for cushioning the movements
thereof. It has been found in practice that this dash pot gives rise to certain
inconveniences, inasmuch as it is liable through corrosion, or from becoming
clogged or choked with dirt or other foreign matter, to become inoperative unless
subjected to periodical inspection and cleaning to maintain it in working order.
The object of our present invention is to enable this dash pot arrangement or
other mechanical cushioning of the pivoted beam or lever, to be dispensed with,
and to provide for effecting this cushioning automatically by means of the
electric current.
According to our invention we wind both the above mentioned coils or solenoids
with thick wire, one being, however, wound with, a layer or other suitable pro-
portion less wire than the other so as to render it normally when magnetized
slightly weaker, and thus to enable the other or stronger coil or solenoid to
operate the movement of the pivoted beam or lever at the proper time as herein-
after described. To admit of the weaker coil or solenoid operating the movement
of the pivoted beam or lever when necessary, we wind the said weaker coil or
solenoid with a few layers of fine wire, which, upon the carbon points becoming
too far apart and thereby increasing the resistance of the arc, will become more
powerfully magnetized and thus impart sufficient preponderance to this coil or
solenoid to attract its core or plunger and withdraw that from the other coil
or solenoid. Upon the carbons again approaching each other and thus decreasing
the resistance of the arc, less current will flow through the shunt or fine winding
and the said coil or solenoid will again become less powerful than the other, and
so on, as the resistance of the arc varies.
It will be seen that as the alternate preponderance of each coil or solenoid over the
other is slight, only being sufficient to effect the movements of the pivoted beam or
lever, the movements of the latter in either direction will be cushioned or regulated

page_text: by the said weaker series winding, and that the provision of any mechanical
device for that purpose is thus rendered unnecessary.
It will be obvious that our invention is also readily applicable in cases where
more than two coils or solenoids are employed. Also that instead of the above
mentioned layers of fine wire upon the weaker coil or solenoid, a small separate
or auxiliary coil or solenoid having a core or plunger suspended from the pivoted
beam or lever may be employed. This coil or solenoid becomes more powerfully
magnetized when the resistance of the arc is increased by reason of the separation
of the carbons, and the said current consequently passing through the shunt
circuit. The attraction exercised upon its core or plunger by the small separate
or auxiliary coil or solenoid is sufficient to cause the balance of power to become
in favour of the core or plunger with the weakest winding and consequently to
enable this latter to operate the movement or adjustment of the pivoted beam or
lever. Upon the said auxiliary coil or solenoid becoming weaker by reason of
the decreased resistance of the are the pivoted beam or lever is again moved by
the stronger coil or solenoid as before.
Total this tot dow of
1900
A. F. SPOONER,
124, Chancery Lane, London, W.C., Agent for the Applicants.
Improvements relating to Electric Arc Lamps.
We, WILLIAM REGINALD RIDINGS, of Fairview, Bristol Road, Bournbrook, in
the County of Worcester, Engineer, and JouN HENRY CRAWFORD, of 7, Broad
Street Avenue, in the City of London, 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 and by the following statement:-
Our invention relates to the brake mechanism of electric arc lamps, and more
especially to apparatus of that kind or class described in the Specification accom-
panying previous Letters Patent granted to one of us conjointly with George
Frederick Bull and Llewellyn Burbank Codd, No... 7788 of 1895.
In the said former Specification an arrangement is described wherein a
or plunger is suspended at each end of a pivoted beam or lever, which cores or
plungers are excited respectively by a series and a shunt coil so as to effect,
through a series of levers a drum or friction wheel and a pad or roller or the
equivalents, either the striking of the arc or the feeding of the carbons towards
each other.
To prevent the above mentioned pivoted beam or lever from being operated too
abruptly, a dash pot is provided for cushioning the movements thereof. It has
been found in practice that this dash pot gives rise to certain inconveniences
inasmuch as it is liable, through corrosion or from becoming clogged or choked
with dirt or other foreign matter, to become inoperative unless subjected to
periodical inspection and cleaning to maintain it in working order.
The object of our present invention is to enable this dash pot arrangement ör
other mechanical cushioning of the pivoted beam or lever to be dispensed with,
and to provide for effecting this cushioning automatically by means of the electric
current.
. In the accompanying drawings,
Figure 1 serves to show a front view of the lamp mechanism and one way of
carrying out our invention..
:
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page_text: Figure 2 serves to show a side view of the mechanism and an alternative
arrangement of coils, and
Figure 3 serves to show a rear view of the mechanism and a further modifica-
tion of the arrangement of coils.
Like letters indicate corresponding parts throughout the drawings.
a is the frame of the lamp; b is a coil or solenoid wound in series with the
arc; c is a coil or solenoid wound in shunt, and b, c are the cores or plungers
thereof, which latter are suspended as shown from a pivoted beam or lever d.
According to our present invention the shunt side of the lamp is provided with
an additional winding e forming part of the series circuit and which while being
similar to, but composed of a smaller number of turns than, the main series coil b,
possess sufficient magnetic attraction on its core to steady any sudden pull either
on the plunger of the series coil or that of the shunt coil.
Figure 1 shows the shunt coil c wound for the purpose of our invention with
an internal winding of coarse wire e and an exterior one of fine wire .
Figure 2 shows the shunt coil c formed in two parts insulated from each other,
the upper or one part having the coarse winding e and the lower or other part the
fine winding ².
Figure 3 shows the additional winding e upon a separate bobbin, the coil so
formed having a separate core or plunger e suspended from the pivoted beam or
lever d.
The series circuit may be traced from the terminal f of the lamp to the coarse
winding e and from thence to the main series coil b and finally to the frame of
the lamp. The shunt coil is connected across the terminals of the lamp.
The drum or friction wheel g has two cords or the like g' and g² attached to it.
g runs past guide pulley through the lamp bed to the lower carbon holder,
whilst runs past guide pulley to the upper carbon holder.
Normally the upper carbon rests upon the lower one. Upon the current
entering the lamp the series plunger is pulled down thus putting a tension on
the brake chain and taking the drum or friction wheel g round. Thus the
cords g' and 2 are inversely operated and the carbons caused to separate. As the
are becomes too long the shunt coil c gets more highly magnetized by reason of
the increased resistance of the arc. The plunger c is thereupon pulled down
within its coil c, until the screw j comes in contact with the stop k. This takes
the pressure of the weight 7 off of the brake chain h. The said chain is secured
to a lever m which is fulcrumed at two points namely m' upon the lever d, and m²
upon a link n which latter in turn is fulerumed at upon the weight 7. In this
way the tension of the chain h upon the wheel g is released and the latter is free
to rotate so as to feed the carbons towards each other owing to the preponderating
weight of the upper carbon holder.
It will be seen that the additional winding e continuously exerts an attractive
influence upon the core within it and thus steadies the operation of the brake
mechanism either in the one direction under the influence of the main series
coil bor in the other direction under the influence of the shunt coil c. In this
manner all undue movement or any sudden jerk of the lever d, which causes an
intermittent unsteadiness of the light, is obviated and the lamp rendered regular
in its working.
Although we have described the additional winding or coil e as forming part
of the series circuit and operating upon the shunt or opposite side of the lamp
(and by preference it is so arranged) obviously the additional winding or coil
might form part of the shunt circuit and operate upon the series side of the lamp.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:
1. In an electric arc lamp the means, substantially as set forth, for steadying
the operation of the brake mechanism electrically.

page_text: 2. In an electric arc lamp wherein a series and a shunt coil are employed the
additional winding or coil forming part of the one circuit, but located on the
opposite side of the lamp, operating to continuously exert an attractive influence
upon the core within it and thereby to steady the movement of the brake
mechanism, substantially as set forth.
3. In combination, in an electric arc lamp, a series coil and a shunt coil, means
brought into operation thereby for striking the arc and maintaining the feed,
and an additional winding or coil forming part of the one circuit but located on
the opposite side of the lamp serving to steady the operation of the mechanism
substantially as set forth.
4. The construction, arrangement and combination of parts constituting our
improvements in electric arc lamps substantially as set forth and as illustrated in
the accompanying drawings.
Doted this lat dor of October 1807
A. F. SPOONER,
323, High Holborn, London, Agent for the Applicants.