Improvements in Electric Arc Lamps.
Year: 1898

page_text: Improvements in Electric Arc Lamps.
I, ARTHUR MARSHALL ARTER, of Linden House, Upper Mall, Hammersmith.
in the County of Middlesex, Engineer, do hereby declare the nature of this inven-
tion to be as follows:-
This invention relates to improved means of automatically regulating the length
of the voltaic are of a lamp adapted to work either with continuous or alternating
currents, and it has for object to provide regulating mechanism that shall be
efficient in operation and simple and cheap in construction.
According thereto the positive carbon holder is made heavier than the negative.
carbon holder and both are suspended from flexible connections such as cords which
pass around opposite sides of a drum or pulley that is carried by a spring-con-
trolled lever and is provided with a boss or part of smaller diameter from which
depends a cord having attached thereto the core of a solenoid, the arrangement
being such that when no current is passing through the lamp the weighted top
carbon will normally touch the bottom carbon so that upon the lamp circuit being
completed an electric current will pass through the carbons and the solenoid
whereupon the core will be pulled down thereby pulling down the pulley against
the action of the spring so as to move the carbons a suitable distance apart to
strike the are in which position they will be automatically maintained against the
action of the weighted top carbon holder which normally tends to bring the
carbons together.
In one construction of focussing lamp according to this invention, the positive
and negative carbon holders are carried by suitably guided rods having bands,
chains or the like connected thereto, the cord from the top carbon holder passing
suitable fixed
over a guide pulley carried by a
support and thence
to a groove on the larger diameter of a differential pulley to which
it is secured, whilst the cord from the bottom carbon holder
passes to
another groove on the said larger diameter of the differential pulley and is also
secured thereto, the cords depending from opposite sides of the pulley. A smaller
diameter portion of the differential pulley has secured thereto a cord which depends
from the same side as the cord of the bottom carbon holder and carries at its lower
end the core of a series solenoid that is so arranged that its centre line is sub-
stantially tangential to the periphery of the smaller diameter part of the differential
pulley. The differential pulley is rotatably mounted upon a spindle which
is carried by a lever or pair of levers suitably hinged or pivoted at one end to a
fixed support so as to move about an axis which may coincide with that of the
aforesaid guide pulley. The free end of this lever or of the pair of levers is sup-
ported by a spring (or springs) which normally tends to raise said lever and with
it the differential pulley when the same has been drawn downward by the solenoid
core. A dashpot or its equivalent may be provided for example at the bottom of
the solenoid core or it may be in connection with the lever or levers in order
to wracant hunting

page_text: The operation is as follows:-When the lamp circuit is closed and the solenoid
is energized as already described, the hinged lever is pulled down slightly and
with it the differential pulley thus lowering the bottom carbon holder and normally
tending to rotate the pulley in one direction thus overcoming the tendency of the
weighted top carbon holder to rotate the differential pulley in the opposite direction.
In this movement of the solenoid core the top carbon holder is not affected, or
in some cases, it may be lowered a short distance. According as the resistance
of the are varies, a correspondingly increase or decreased current will pass through
the solenoid which thus acts to pull the core more or less against the action of the
spring. As the carbons burn away and less current passes, the spring will slightly
raise the lever carrying the differential pulley with it and bring the carbons closer
together again. As the tension of the spring decreases on account of the further
consumption of the carbons and the pull of the core plus the weight of the bottom
carbon holder no longer counteracts the pull of the weighted top carbon holder
the pulley will partly turn or rotate thus lowering the top carbon and raising the
bottom, whereupon more current will pass through the solenoid which will act
upon the core so as to stop further rotation of the pulley and at the same time
pull the lever or levers down thus regulating the length of the are between the
carbons.
The length of the solenoid and core are such as to allow of their properly regulat-
ing the length of the are notwithstanding the fact that the core will be gradually
moved outward as the differential pulley winds up the cord attached to the core.
It will be understood that the current flowing through the solenoid does not raise
the top carbon holder but only counteracts the effect of its weight this weight
causing the top carbon to be lowered when the current is reduced, the bottom
carbon being moved up or down according to the resistance of the arc.
1000
I, ARTHUR MARSHALL ARTER, of Linden House, Upper Mall, Hammersmith,
in the County of Middlesex, Engineer, do hereby declare the nature of this inven-
tion 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 improved means of automatically regulating the length
of the voltaic arc of a lamp adapted to work with either continuous or alternating
currents, and it has for object to provide regulating apparatus that will be efficient
in operation and yet simple and cheap in construction.
According thereto the top carbon holder is made heavier than the bottom carbon
holder and both are suspended from flexible connexions such as cords which pass
around and from opposite sides of a pulley that is carried by a spring-controlled
lever and is provided with a boss or part of smaller diameter from which depends a
cord having attached thereto the core of a solenoid, the arrangement being such
that if no current be passing through the lamp the weighted top carbon will
normally touch the bottom carbon so that upon the completion of the lanip circuit
an electric current will pass through the carbons and the solenoid, whereupon the
core will be pulled down, thereby pulling down the pulley against the action of the

page_text: spring so as to move the carbons a suitable distance apart to strike the arc, after
which the carbons will be automatically maintained at such a distance apart against
the action of the weighted top carbon holder, which normally tends to bring, the
carbons together.
A focussing lamp according to this invention is represented, by way of example,
in sectional elevation and in sectional plan respectively by Figs. 1 and 2 of the
accompanying drawings. In such a lamp the positive and negative carbon
holders 1 and 2 are carried by rods 3 and 4 suitably guided as by and in tubes 3"
and 4 and having bands, chains, or the like 5 and 6 connected thereto, the cord 5.
from the top carbon holder 1 passing over a guide pulley 7 carried by a suitable
fixed support 8 and thence to a groove 9 on the larger diameter portion 10 of a
differential pulley P to which it is secured, whilst the cord 6 from the bottom
carbon holder 2 passes to another groove 11 on the portion 10 of the differential
pulley and is also secured thereto, the cords 5 and 6 depending from opposite
sides of the pulley P. A smaller-diameter portion or boss 12 of the differential
pulley has secured to it a cord 13 which is coiled round this portion or boss 12
and depends from the same side as the cord 6 of the bottom carbon holder and
carries at its lower end the core 14 of a series solenoid 15 that either is so arranged
that its centre line is substantially tangential to the periphery of the smaller-
diameter portion or boss 12 of the differential pulley P, or, as shown and preferred,
is attached to a lever 16 which is pivoted at 17 and to the outer end of which
the core 14 of the solenoid is then connected. The differential pulley P is rotatably
mounted upon a spindle 18 which is carried by a lever arm or pair of lever arms 19
suitably pivoted at one end to a fixed support as at 17 to the fixed support 8, so as
to move about an axis which may coincide with that of the guide pulley 7 but which
may, as is preferred and shewn in Fig. 1, he arranged below that of the guide
pulley. The free end of the lever arm or of the pair of lever arms 19 is supported
by a spring 20 (or springs) which tends to raise the lever arm or lever arms 19
and with it or them the differential pulley P' after the same has been drawn down-
ward by the solenoid core 14. A dashpot or its equivalent may be provided-for
example, at the bottom of the solenoid core, or, it may be, in connexion with the
lever arm or lever arms, in order to prevent hunting. In the example shown, a ;
short chain 21 is interposed between the cord 6 and the rod 4 of the lower carbon.
holder for the purpose of temporarily taking up the slack of the cord 6 and so
preventing the said cord from being lifted off the pulley P if the lower carbon
holder be jerked or lifted suddenly.
The operation is as follows:-
When the lamp circuit is closed and the solenoid 15 is energized as already.
described, the lever arm or arms 19 are pulled down slightly and with them the
differential pulley P, the solenoid thus lowering the bottom carbon holder 2 and,
by its tendency to rotate the pulley in the direction indicated by the arrow,
gradually overcoming the tendency of the weighted top carbon holder 1 to rotate -
the pulley in the opposite direction, and thereby striking the arc;
during this movement but before striking the are, the top carbon holder. I
is slightly lowered; in some cases, however, the top carbon holder may
be unaffected. As the resistance of the arc increases through the burning away of
the carbons, a correspondingly decreased current passes through the solenoid, so
that the pull of the core plus the weight of the bottom carbon holder no longer
counter-balances the pull of the weighted top carbon holder, and the pulley then
partly rotates, thus lowering the top carbon and raising the bottom one, whereupon
more current passes through the solenoid, which acts upon its core so as to stop
further rotation of the pulley and thus regulates the length of the are between the
carbons. As the carbons burn away. the weight supported by the spring is, of
course, reduced, and the spring slightly raises the lever arms 19 and with them
the differential pulley, so rendering the position of the are slightly higher than
it otherwise would be. The strength of the spring 20 is such that when no current

page_text: is passing through the lamp it supports the pulley and parts carried thereby, and
when the arc is being struck it expands to such an extent that the resistance of the
arc is consistent with the passage of normal current through the solenoid.
The lengths of the solenoid and its core are such as to allow of their properly
regulating the length of the arc notwithstanding the fact that the core will be
gradually moved outward as the differential pulley winds up the cord 13 attached to
the core.
When the lamp is intended to be worked in series with others, a differentially
wound or combined series shunt solenoid may be employed instead of a simple
series solenoid.
The apparatus might, as will be obvious, be inverted-i.e., the wlieel and its sole-
noid be placed below the carbons. In that case the cords 5 and 6 might be attached
to upwardly extending rods carrying the carbon holders 1 and 2 respectively.
Also instead of arranging for the carbons to be fed at equal rates, they may be
given different rates of feeding, as by passing the cords from the two carbon holders
round portions of the pulley of different diameters, and in this way an equivalent
of the difference in weight of the carbon-holders hereinbefore mentioned may be
arrived at.
Arc lamps of the kind hereinbefore described in which the two carbon-holders
are so connected to a wheel that rotation of the latter will move the carbon-holders
in opposite directions and in which the wheel is connected to a magnetic device
adapted normally to counterbalance the force tending to bring the carbons together
can be variously constructed.
Fig. 3 shows in side elevation a modified construction of are lamp wherein the
arms 16 and 19 are mounted on a spindle 17 that passes through a slot 22 in the
pulley P and the cord 5 passes vertically downwards from the said pulley, the guide-
pulley being omitted; the arrangement is such that when the current is switched
on, the solenoid 15. first pulls the axle of the pulley P down whilst the weight of
the top carbon holder 1 rotates the pulley slightly in the direction indicated by the
arrow b and the carbons both descend for a short distance touching each other, and
as the tension of the spring, and consequently the resistance to the lowering of the
axle of the pulley increases, the solenoid stops the rotation of the pulley about its
own axis in the direction indicated by the arrow and strikes the are by revolving
the pulley P together with the arms 19 about the axis 17. The spring 20 is
arranged in an inclined position in order that a less force, than would be required
if the spring were vertical, may be necessary, after the spring has been expanded
by the weight of the parts supported by it, to produce the requisite lowering of the
axle of the pulley in striking the arc. In the case of a continuous current lamp,
the pulley I may be provided with a weight 23 or its centre of gravity may be so
arranged that it will compensate for the gradual decrease in the tendency of the
carbon-holders to approach each other due to the consumption of the carbons. In
the case of an alternating current lamp this is unnecessary, but in this case the
core 14 of the solenoid is preferably composed of discs of iron arranged at right.
angles to the axis of the solenoid. It is obvious that, in the case of a lamp such as
shown in Fig. 3, a toothed wheel may be substituted for the grooved pulley P, and
racks, engaging therewith, for the cords 5 and 6. It is to be understood that the
features of the lamp shown in Fig. 3 in so far as it differs from that shown in
Figs. 1 and 2 are not herein claimed as forming part of the present invention and
I intend to obtain separate Letters Patent therefor, on an application already made
and numbered No. 27636 of 1898 and they are herein described only in order to
explain the best way now known to me of carrying out my said invention.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:-
:-
1. An electric are lamp in which the two carbon-holders are so connected to a
wheel that rotation of the latter will move the carbon-holders in opposite directions,

page_text: and in which the wheel is connected to a magnetic device adapted normally to
counterbalance the force tending to bring the carbons together.
2. An electric are lamp according to the preceding claim in which the wheel is
supported elastically so as to allow motion thereof in the direction of magnetic
force.
3. An electric are lamp according to Claim 2 in which one of the carbon-holders
is connected with the wheel by a flexible connexion which passes over a guide
pulley so situated that the initial energizing of the magnetic device will move
the wheel in such a manner as to separate the carbons and strike the arc.
4. My improved electric arc lamp constructed as hereinbefore described with
reference to and shown in Figs. 1 and 2 of the accompanying drawings.
Dated this 14th day of March 1899.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.