Improvements in and connected with Electric Arc Lamps.
Year: 1891

page_text: Date of Application, 3rd Mar., 1891-Accepted, 18th Apr., 1891
COMPLETE SPECIFICATION.
Improvements in and connected with Electric Arc Lamps.
I, LUTHER HAMILTON BUCHANAN, of Pasadena, Los Angelos, California, in
the United States of America, Electrician, 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 to arc lamps and my improvements include the construction
of the carbons, the means for feeding them, and the cut out.
My object is to produce an arc lamp that will burn a great length of time while
still employing but one set of carbons, and which lamp when burning, will throw no
objectionable shadow. This object I attain by means of the construction and
combination of parts in which my invention consists as hereinafter described and
claimed.
In the accompanying drawings,
Figure 1 is a side elevation, partly in section, of my complete lamp;
Figure 2 a longitudinal section on line 2-2 of Figure 1, a portion of the feed
wheel being broken out;
Figure 3 a detail plan of the carbons, and
Figure 4 a detail view of the coils taken from the side opposite that of Figure 1,
and shewing the cut out connections.
In the upper part of a suitable frame a are secured the main and shunt coils A
and B respectively, and to a stude is pivoted the armature C having sides or wings
adapted to overlap or partly encircle the cores of the coils alternately, as the
armature may be more or less attracted by either of said coils. On each side of the
pivot stud c is a set screw c¹ to limit the swing of the armature.
A downwardly projecting extension c² of the armature engages the edge of the
feed whcel D when moved in the direction of the arrow, Figure 1, by the attraction
of the coil A, and is retracted by a suitable spring c³. This feed wheel is secured
to the upper end of the short vertical shaft G, and is provided with an elastic
periphery preferably consisting of a round rubber band fitted to a peripheral
groove of the wheel; this is to ensure a better engagement of the armature extension
with the wheel to rotate it. The lower end of shaft G has a bevel pinion g
which engages a bevel pinion H of insulating material, which in turn, engages with
a bevel pinion g' on the upper end of a short vertical shaft G. A bracket J
secured to the under side of the frame has four horizontal arms 1, 2, 3, and 4 of
insulated or insulating material. The upper shaft G has its bearings in the frame.c
and arm 1, the pinion H has its horizontal bearings in the arm 2 and a vertical
extension of the arm 4; and the lower shaft G¹ has its bearings in arms 3 and 4.
It will thus be seen that the two shafts are thoroughly insulated from each other.
Above the frame 2, the shaft G has a sleeve F loosely mounted upon but capable
of being secured to it by means of set screw and to this sleeve is secured the
inner end of a coil spring E, the other end of which is secured to the frame at e.
The tension of the spring is adjusted by turning the sleeve F on the shaft and
securing it by its set screw, and the spring is so arranged as to have a tendency to
turn the wheel D in a direction contrary to that in which it is turned by the
armature extension, and to feed the carbons toward each other as hereinafter
explained.
To the shaft G is secured an arm K extending outwards and downwards and
carrying at its end a clip & provided with a set screw for clamping one of the
carbons L in said clip, said clip and carbon being below the plane of the lower end
of the bracket J. To the shaft G' is secured an arm K' extending out to the same

page_text: distance from the centre of the shaft as the arm K and carrying at its outer end a
clip having set screw for clamping the other carbon L and carrying it in the
same plane with that of the carbon L carried by arm K.
These two carbons, as shewn in Figure 3, when new and placed in the clips, form
a nearly complete disc or circle; and each forms a sector, one greater and the other
less than half a circle. In trimming the lamp the arms K K will be turned back
against the action of spring E until nearly or quite in contact with the two sides of
bracket J the carbons will now be secured in the clips, and the spring will cause
their radial edges 1, 1' to abut against each other.
The positive wire from the dynamo or other source of electrical energy after
passing through the large coil A is connected to the arm carrying the larger sector
carbon in any ordinary or preferred manner and the other or negative wire is
similarly connected to the arm carrying the smaller sector carbon; or the said
wires may have spring contacts pressing directly against the surfaces of the sectors.
In operation, when the current is turned on, the energizing of coil A will attract
the armature towards it and cause the extension c² to engage the wheel and rotate
the shafts against spring E to separate the edges 1, 1', thus striking the are which
will be formed at some point between said edges, usually at the centre 12, and from
said starting point will move back and forth between the edges 1 11 the arc
remaining at the point where the two edges approach each other most closely, and
when this point is somewhat consumed, moving to the next points which are nearest
together.
When the edges have been consumed to such an extent that there no longer
remains a point where the arc of the proper length can form, the increase of current
in the shunt coil B and decrease in main coil A, cause the armature C to move
toward the coil B, and its extension 2 to leave the wheel D; the spring E now
feeds the carbons in the manner above described until the arc is of the proper length,
and the current in coil A causes the extension of the armature to again engage the
wheel and prevent further feed.
Referring now particularly to Figure 4; my improved cut out may be described
as follows:-A metallic strip A' is secured as by screws a, to the insulated heads
of the coils and is provided with curved ends a, the former being adjacent to
but not in contact with the upper side of the projecting end of the iron core of coil A
and the latter being similarly arranged with respect to, but underneath, the end of
the core of coil B. A. curved strip a of soft iron is pivoted to the head of coil A,
and extends under its core and a similar strip is similarly pivoted with relation to
the core of coil B; at their pivotal points these two curved strips have connections a³
and 63 respectively with the wire of the main circuit, one each side of the carbons
and the strip a has a curved spring or thin strip of metal a secured to it and
carried over the core and between it and the end a' when the pivoted strip a² is
attracted by the magnet A.
The cut out operates as follows:-When the current enters the lamp and its
coils A and B, the two curved strips are attracted to the respective cores, and the
thin spring or strip a' makes contact with the end al of strip or bar A and as long
as there is any current through the lamp remains in this position; at the same time
the curved strip 2 is lifted from the end of bar A and thus prevents short
circuiting through said bar. But if coil B should be broken or burnt out, the
attraction for strip 62 would cease, and it would fall in contact with the end of
bar A and thus cut the lamp out, the current flowing through the coil A, connec-
tion a, strip a², spring a, strip or bar A², strip 2 and connections ³ back to the
dynamo.
From the foregoing, taken in connection with the accompanying drawings, it will
be seen that the construction and arrangement of my lamp is such that the vertical
dimensions are inuch less than can be had in the ordinary are lainp in which
vertical carbons are employed, and that consequently the lamp can be placed in
rooms or show windows having low ceilings; the carbons having their contiguous

page_text: edges 1, 1, elongated and in substantially the same horizontal plane; there are no
parts of the lamp below the arc and no objectionable shadows are cast, and the
large amount of carbon that can be obtained in the discs or sectors is such that the
lamp can be used a very long time without trimming.
It is obvious that I may secure one of the carbon sectors against motion and
feed the other sector only, without departing from the principle of my invention.
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. In an arc lamp, the combination with two sector shaped carbons, of supporting
and carrying arms therefor, one of said arms being pivoted to a support, the centre
of the pivot and the inner ends of the radii of both sectors being in alignment
substantially as described.
2. In an arc lamp, the combination with two sector shaped carbons of pivoted
supporting and carrying arms therefor, the centre of the circle of which the
carbons are sectors being in line with the centre of motion of the arms, and gearing
between the said arms, substantially as described and illustrated.
3. In an arc lamp, the combination with two sector shaped carbons, of pivoted
carrying arms therefor, the centre of the circle described by the carbons being in
line with the centre of motion of the arms; gearing between the said arms, a
wheel carried by the shaft of one arm, a magnet and armature for moving said
wheel in one direction, and a spring for moving the shaft and wheel in the other
direction, substantially as described and illustrated.
4. In an arc lamp, the combination with a pair of carbons, one of which is
connected to an arm carried by a rotary shaft, of a wheel secured to said shaft, a
magnet having a portion of its armature engaging the periphery of said wheel,
and a spring for rotating said shaft, substantially as described and as illustrated.
5. In an arc lamp, the combination with a pair of carbons, one of which is
connected to an arm carried by a rotary shaft, of a wheel secured to said shaft and
having an elastic periphery, and a magnet having its armature engaging said
periphery, substantially as described and as illustrated.
6. In an arc lamp the combination with a pair of carbons, one of which is
connected to an arm carried by a rotary shaft, of a wheel secured to said shaft and
having an elastic periphery, a magnet having its armature engaging said periphery,
a sleeve adjustably secured to the said shaft and a spring having one end secured
to the sleeve and the other end to the frame, substantially as described and as
illustrated.
7. In an arc lamp, the combination with a pair of carbons one of which is
connected to an arm carried by a rotary shaft, of a wheel secured to said shaft,
main and shunt magnets in the circuit of the lamp, a pivoted armature having a
wing for each magnet and an extension engaging the periphery of the wheel, and
an adjusting screw each side of the pivot of the armature, substantially as described
and illustrated.
8. In an arc lamp, the combination with the frame, of the bracket having
insulated arms 1, 2, 3, and 4, a shaft journaled in the lower arms 3 and 4 and
having an arm carrying a carbon, a shaft journaled in the upper arm 1 and the
frame, and having an arm carrying the other carbon, a bevel pinion on each shaft,
and an intermediate pinion of insulating material meshing with said shaft pinions
and journaled to the arm 2 of the bracket substantially as set forth and illustrated.
9. A cut out for are lamps consisting of main and shunt coils, a metallic bar
extending from one coil to the other but insulated therefrom, an armature of the
main coil connected also to the main circuit and having an extension adapted to
make contact with one end of the said bar, and an armature of the shunt coil
connected to the main circuit, and adapted to make contact with the other end of
said bar when released by the core of said shunt coil, substantially as described
and illustrated.

page_text: 10. The combination with the coils A and B of the bar or strip A', the pivoted
strips a², and, the former having an extension at, and connections from the two
pivoted strips to the main circuit, substantially as described and as illustrated.
Dated this 2nd day of March A.D. 1891.
WILLIAM E. HEYS,
Agent for the Applicant.