Improvements in Electric Arc Lamps.
Year: 1894

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
I, WILLIAM JAMES DAVY, of 161 Huddleston Road, Tufnel Park, in the
County of Middlesex 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: -
This invention for Improvements in Electric Are Lamps relates to focussing
lamps in which the positive and negative carbon holders are connected together by
a cord passing over a pulley and in which the upper carbon holder tends to descend
by gravity and thus at the same time to draw up the lower carbon holder so as to
bring the two carbons into contact; and consists in an improved arrangement for
striking and maintaining constant the arc consisting of a gravity friction grip device
acting on the cord and regulated by series and shunt solenoids.
In the accompanying two sheets of illustrative drawings:-
Fig. 1 is an elevation, the hood shades solenoids and friction grip brake being
supposed removed, of a single lamp constructed according to this invention.
Fig. 2 is a sectional elevation of the solenoids and friction grip brake.
Fig. 3 is a plan of the upper part of the lamp with the hood removed.
Fig. 4 is a plan of the travellers and their guides and of the solenoids.
Fig. 5 is an elevation of the gravity friction grip device, and Fig. 6 is a plan of
the same.
Fig. 7 is a sectional elevation of a duplex lamp constructed according to this
invention and
Fig. 8 is a plan of the upper part of the lamp and of the friction grip devices and
Fig. 9 is a plan of the travellers and its guides and the solenoids.
The guide rods a for the lower carbon traveller and the guide rods c for
the upper carbon traveller d are secured to the non conducting discs e and f, the
distance between the rods a and also between the rods c being determined by the
tie washers g. Mounted in projections depending from a saddle bracket secured
to the disc e is a spindle i which carries the loose cord pulleys ; and the fixed
regulating brake levers k connected by links at one end to the core of the series
solenoid m and at the other end to the core n of the shunt solenoid o, both solenoids
being carried from the underside of the disc e. By using non conducting discs or
supports the several parts of the lamp are thoroughly insulated from one another
and a sound solid frame obtained.
"
P
The upper carbon traveller d is guided by means of small grooved rollers fixed
at the extremities of the traveller d and bearing on the rods c and carries the upper
carbon holder ५. The lower carbon traveller is guided by a single grooved
roller mounted at its upper end and bearing between the two rods a and is attached
to a depending tail rods having a tapered end on which is secured the lower carbon
holder t by the fly nut u. The two travellers bd are connected together by the
cord w passing over the loose pulley ; and between the friction grip device carried
by the levers k.
The guiding arrangement allows of the use of longer carbons or the reduction
of the length of the lamp and the method of attaching the lower carbon holder
enables the carbons to be easily set in line.
The friction grip device consists of the four pairs of links 1, 2, 3, 4, jointed
together at the points 5, 6, 7, 8 and suspended from the regulating levers k at the
point 5 at a slight distance from the spindle i forming the fulcrum of the regulating
levers k. Each pair of lower links carries a jaw or grip 9 between which the
cord w passes. Normally the jaws rest on the plate e.

page_text: The operation of the grip device is as follows:-On the current passing to the
lamp the core of the series solenoid in is drawn down and by means of the
regulating lever k draws up the point of support 5 of the friction grip links. This
motion of the point 5 causes the jaws 9 to grip the cord w, the jaws still resting on
the plate e.
As soon as the jaws grip the cord, the relative motion of the
points 5, 8 is stopped and the whole friction grip device is raised with the point 5
and raises with it the cord to and so the arc is struck. As the resistance of the arc
increases due to the burning away of the. carbons and consequent lengthening of
the arc the power of the series solenoid decreases and gradually the friction grip
device is lowered on to the plate e and the jaws begin to relax their hold on the
cord w and a continuous and steady feed is obtained by the cord feeding slowly
through the jaws 9. If the lamp is working in series the shunt solenoid o which
is connected across the terminals of the lamp helps to feed the carbons together and
maintain a steady arc. In order to still further increase the steadiness of the arc
the piston of a dash pot is attached by a link to the regulating lever k.
The duplex lamp shown in Figs. 7, 8, 9 is actuated by one striking and regulating
mechanism there being two sets of travellers bb' and d d' and carbons, two
cords w w¹ and pulleys jj and two friction grip devices actuated by one set of
regulating levers k and solenoids m o. The duplicate parts are similar to those
described for the single lamp and are indicated respectively by the same reference
letters the second set being indicated by a dash to the letter. Also two series
cores and solenoids m m' acting together are shown.
The lamp is suspended by the eye A screwed into the saddle bracket h and
secured by a lock uut. The hood B fits over the eye A and is secured by the
milled nut C. The bell hood D flanges into and depends from the plate e and is
secured by the hood B whose lower edge passes over the upper edge of the bell
hood D as clearly shown. The cover and hood can thus be firmly fixed or removed
by hand without removing the conducting wires. The spring clips E for carrying
the globe F are riveted to the bell hood D. The reflector or shade G is booked
over the lips of the globe F. A mica disc H protects the lower disc f and thus
the working parts of the lamp from injury from the ascending gases from the arc.
The current enters the lamp at I thence through the series coil m to the holders
of the upper carbons through the carbons tail rods and holders for the lower
carbons to the terminal J. The shunt coil o is connected across the terminals I J
in the usual manner. The friction grip devices of the two sets of carbons are
arranged so that one set when the regulating levers k are actuated leaves the disc e
before the other.
The operation of the duplex lamp is as follows:-Ou the current passing to the
lamp the regulating levers k raise the friction grip devices and the first to leave
the plate e simply separates the corresponding carbons, leaving the first pair of
carbons that is the pair to be first consumed-still in contact. On the further
motion of the regulating lever the friction grip devices of the first pair of carbons
leaves the disc e separates the points of the carbons and strikes and maintains the
arc. During the time that the first set of carbons are burning the grip of the
second set of carbons keeps its grip on their cord and keeps the points apart.
When the holders of the first set of carbons come to rest on the framework of the
side rods a c and cannot feed further together the lever gradually lowers the grip
devices until the second device comes in contact with the disc and releases the
second cord of the second set of carbons which then come in contact and the first
set are immediately extinguished. The regulating levers k then again raise the
grip devices and strike the arc for the second pair of carbons which continue to
burn until completely consumed.
In a similar inanner a lanip with three or more pairs of carbons can be operated
by a single striking and regulating mechanism.
"
As shown the upper or + carbon is double the size of the lower or
carbon so
that the focus of the lamp is constant. In alternating current lamps the carbons
may be of the same size.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what 1
claim is :-
1. In electric arc lamps in which the positive and negative holders are connected
together by a cord passing over a pulley and in which the tendency of the carbon
holders is to approach, the gravity friction grip device consisting of a system of
links pivoted together to form a closed frame, of grip jaws between which passes
the part of the cord or connecting device tending to move downwards and which
are attached to the jointed frame in such position that they approach one another
as the frame elongates in a vertical direction, of a stop on which the lower end of
the link frame rests and of a means for determining the position of the upper end
of the frame relatively to the said stop according to the resistance of the lamp
substantially as described.
2. In electric arc lamps in which the positive and negative holders are connected
together by a cord passing over a pulley and in which the tendency of the carbon
holders is to approach, the gravity friction grip device consisting of a lever mounted
on the spindle of the loose cord pulley, of a means for determining the position of one
end of the lever according to the resistance of the lamp, of a system of links
suspended from the lever and pivoted together to form a closed frame, of grip jaws
between which passes the part of the cord or connecting device tending to move
downwards and which are attached to the jointed frame in such position that they
approach one another as the frame elongates in a vertical direction, and of a stop
on which the lower end of the link frame rests substantially as described.
3. In electric arc lamps in which the positive and negative holders are connected
together by a cord passing over a pulley and in which the tendency of the carbon
holders is to approach, the arc striking and maintaining mechanism consisting of a
lever mounted on the spindle of the loose cord pulley, of a solenoid core attached
to the lever, of a corresponding solenoid arranged in series, of a system of links
Buspended from the lever in such manner that they are raised when a solenoid core
is drawn into its coil and pivoted together to form a closed frame, of grip jaws
between which passes the part of the cord or connecting device tending to move
downwards and which are attached to the jointed frame in such position that they
approach one another as the frame elongates in a vertical direction, and of a stop
on which the lower end of the link frame rests, substantially as described.
4. In electric are lamps in which each positive holder is connected to the
corresponding negative holder by a cord passing over a pulley and in which the
tendency of the carbons is to approach, a series of gravity friction grip devices one
for each pair of carbons, and each device consisting of a system of links pivoted
together to form a closed frame of grip jaws between which passes the part of the
cord or connecting device tending to move downwards and which are attached to
the jointed frame in such position that they approach one another as the frame
elongates in a vertical direction, of a single stop on which the lower ends of the
links rest and of a means whereby the upper ends of the frames are raised together
to a height dependent on the current through the lamp the said devices being so
connected to the said means that they are successively raised off the said stop
substantially as described.
5. The improvements in electric arc lamps substantially as described with
reference to the drawings.
Dated this 15th day of March 1901
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.