Improvements in Electric Arc Lamps.
Year: 1890

page_text: Date of Application, 18th July, 1890-Accepted, 22nd Nov., 1890
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
1 JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this invention which has been communicated
to me from abroad by Louis Bardou of Clichy in the Republic of France Electrical
Engineer and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
This invention relates to an improved construction of arc lamps as hereinafter
described with reference to the accompanying drawings.
Fig. 1 of the accompanying drawings represents in elevation and partly in section
the upper part of an arc lamp constructed according to this invention. The lower
part including the carbons may be of any ordinary or suitable construction and is
not shown in the drawing.
Fig. 2 is a side elevation of the lamp viewed at right angles to the view in Fig. 1.
Fig. 3 represents the lamp in horizontal section on the line 1-2 Fig. 1 and
Fig. 4 represents a similar section on the line 3-4 Fig. 2.
Figs. 5 and 6 illustrate a modified arrangement of the mechanism as hereinafter
described.
Referring to Figs. 1 to 4 of the drawings the lamp is provided with a cord or band a
from one extremity of which a rod 11. forming the upper carbon holder is suspended.
This cord passes over a pulley band under a pulley e from which the lower carbon
holder constructed with a horizontal har 15 and two vertical rods 14 is suspended. The
other end of the cord is attached at O to one end of a lever 2 oscillating on a centre S
on a support 5 carried by two of the vertical rods 7 and made of soft iron so as to act
as an armature which is polarised by and increases the power of a solenoid E. The
other end of this lever is bent at right angles to the main part at 1 (Fig. 3) so as to
pass under the end of a lever 3 oscillating on a fixed fulcrum 3' and connected by a
joint (Fig. 3) to the core 10 of the solenoid E arranged in the circuit of the lamp.
The lower end of this core is attached to a spring 9 whose tension can be regulated
by a screw 13. A wheel 8 rotating with the pulley b is arranged with its periphery
in proximity to the lever 3 so that when the latter is raised it comes in contact with
and retards or arrests the rotary motion of the wheel 8 and pulley b.
Suitable binding posts 6 are provided on the upper part of the frame for attaching
the leads or conductors in the usual way.
When the electric current does not pass through the lamp and solenoid the spring 9
draws down the soft iron core 10 pivotally connected with the lever 3 so that the
latter is pulled away from the periphery of the brake wheel 8 which is thereby
enabled to rotate freely. At the same time the lever 3 depresses the shorter arm 1 of
the lever 2 and elevates the end O. Under these conditions the upper carbon
carried by the carbon holder 11 being heavier than the lower carbon carried by the
frame 14-15 descends at the same time raising the pulley e so that the two carbons
come in contact.
Now when the lamp is put in circuit the current is caused to pass through the
solenoid E and through the two carbons. The soft iron core 10 being drawn upward
by the action of the solenoid and of the armature 5 is suddenly raised against the
stress of the spring 9. The lever 3 is moved up and pressed against the periphery of
the brake wheel 8 thus preventing the latter from being rotated by the cord a. The
upper carbon holder 11 which during this quick movement of the lover has not bad
sufficient time to overcome the inertia of the brake wheel 8 is not moved from the
position of rest. The lever 3 in rising releases the shorter arm 1 of the lever 1-2
the latter consequently oscillates on its fulcrum and the extremity of its arm 2

page_text: descends. The brake wheel 8 and the upper guide pulley being clamped for a
moment by the brake lever, the stirrup piece or frame 14-15 and with it the lower
carbon are lowered by the movement of the lever 2 so that the carbons are separated
and the arc is struck.
The two carbons tend to separate more and more as the movements of the levers
continue but the lever 3 immediately comes in contact with the periphery of the
wheel 8 and acting as a brake prevents the upper guide pulley 6 from rotating.
The extremity of the lever 2 also comes in contact with the lever 3 and the
movement of the cord a and carbon-holders being thus arrested the carbons remain
at the same distance apart so long as the current passes regularly or under the same
conditions.
As the carbons gradually burn away and the lengthening distance between them
increases the resistance of the are so that the attraction of the solenoid becomes
weaker the action of the spring 9 predominates and draws down the piece of soft
iron or armature 10 and the lever 3. The brake wheel and pulleys are then free to
rotate so that owing to the preponderance of the upper carbon the two carbons draw
nearer together until the normal resistance is established at the are the same series of
operations being automatically repented whenever the resistance increases.
In place of the arrangement herein before described it is preferable in certain
cases to construct the apparatus in the modified form illustrated in Figures 5 and 6 of
the accompanying drawings. This arrangement is designed to prevent the points of
the carbons from remaining too long in contact in cases where owing to a material
reduction of the electro motive force adhesion between the ends of the carbons is
liable to take place.
It is evident that with the foregoing arrangement when this accidental adhesion
occurs and the electro motive force subsequently regains its normal value a certain
amount of time is required for separating the carbons and reforming the arc as the
carbons cannot be separated until the ends have been sufficiently consumed or burned
away.
In order to obviate this disadvantage the brake lever 3 is replaced in the modified
construction (Figures 5 and 6) by a combination of two levers one of which forms a
supplementary lever carried by the main lever which is pivoted at one end to a fixed
centre and at the other end is acted on by the lever connected to the solenoid core.
Fig. 5 represents (in elevation and partly in section on the line - Fig. 6) the
upper part of the apparatus only the lower part being constructed similarly to the
apparatus illustrated in Figs. 1 and 2. Fig. 6 represents the modified arrangement
in plan.
The general principle of the working is similar to that of the mechanism herein-
before described but the construction and arrangement of the braking and igniting
levers are slightly modified.
The apparatus is constructed with an igniting or starting lever 10 shown in Fig. 6
but omitted in Fig. 5 in order to obtain a view of the supplementary lever 3 carried
by the brake lever 1 and of the spring 6 attached at one end to an arın 9 on the
lever 3 and at the other end to a fixed point 11. This spring is maintained in
tension by a pin 5 projecting from the side of the lever 1 and bearing against the
tail of the lever 3 when the latter is not pressed against the brake wheel. The lever 1
is composed of two bars or beams 1 1 capable of oscillation on a horizontal axis 2
the pin 4 forming the centre of oscillation of the lever 3 being carried by the beam 1.
The free ends of the beams 1, 1¹ are connected together by a jointed piece 7.
The lighting and regulating of the lamp are performed in the same way as in
the arrangement firstly hereinbefore described but this second arrangement of the
apparatus is preferable in case the electro motive force happens to be lowered to any
considerable extent. The solenoid core then ceases to be attracted and the carbons
come into contact. When under these conditions the electro motive force regains its
normal value the intensity or power of the current in the solenoid- increases and
exceeds the normal value owing to the carbons being in contact; the moveable core is

page_text: thereupon sharply attracted and passes beyond the position of equilibrium. It draws
the levers 10 and 1 with it in its movement but the lever 3 turns upon the centre 4
so as to continue to act on the brake wheel.
The movement of the lever 1 allows the extremity of the igniting lever to descend
and produces a supplementary separation of the carbons. This has the effect of
immediately reproducing or striking the electric arc.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1st. The improved regulating mechanism for electric are lamps in which one
solenoid is combined with a combination of levers and brake apparatus for the
purpose of obtaining the lighting and regulating action in the lamp substantially as
herein before described.
2nd. The improved regulating mechanism for electric arcs comprising the
combination of a solenoid and an arrangement for lighting and braking with a series
of pulleys so arranged as to enable both of the moveable carbon holders to be
supported by one cord substantially as hereinbefore described with reference to the
accompanying drawings.
3rd. The several arrangements and combinations of parts constituting the
improvements in are lamps substantially as hereinbefore described.
Dated this 18th day of July 1890.
J. H. JOHNSON & Co.