Improvements in Electric Arc Lamps.
Year: 1895

page_text: Date of Application, 20th June, 1895
Complete Specification Left, 20th Mar., 1896-Accepted, 6th June, 1896
Improvements in Electric Arc Lamps.
I WILLIAM JAMES DAVY, of 4 Parolles Road, Upper Holloway, in the
County of London Engineer, do hereby declare the nature of this invention to be
as follows:-
This invention for improvements in electric arc lamps relates to lamps in which
the positive and negative carbon holders are connected together by a chain or 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 of a friction surface moving with
the pulley, a brake lever with brake shoe in close proximity to the friction surface
and pivoted eccentrically to the friction surface, a lever pivoted concentrically to
the friction surface and carrying the brake lever pivot and of a means for
determining the position of the brake lever according to the resistance of the arc.
Preferably the pulley makes one complete revolution to completely consume the
carbons.
In one form of lamp, constructed according to this invention, the pulley over
which passes the cord connecting together the carbon holders is hollow and the
brake mechanism is contained inside. Two brake levers each carrying a brake
shoe in close proximity to the internal surface of the pulley are mounted loosely
on a pivot carried near the opposite internal surface of the pulley by a carrier
lever mounted loosely on the spindle carrying the cord pulley. The two brake
levers are so arranged that if they be separated the shoes brake or grip on the
internal surface of the pulley. The brake levers are operated from the regulating
solenoid lever by means of a small elliptical cam pivoted to an arm of the carrier
lever and fixed on an arm operated by means of a pin working in a slot or by a
link from the regulating lever. It will be seen that the regulating lever first
causes the brake shoe to grip the pulley and that then the whole will be carried
round with the cord pulley on the carrier lever.
Instead of using a cam to separate the brake lever a jointed system of levers
may be employed and the brake shoe may act ou the external surface instead of
on the internal surface of the pulley.
The periphery of the cord pulley is of vulcanite or similar insulating material
fitted on a flanged metallic pulley and the current is conveyed to the lamp through
the cord itself.
In a modification the usual series coil may be replaced by a spring or weight
tending to operate the regulating lever so that the brake shoes grip the pulley and
finally rotate it to separate the carbons. On the current passing into the lamp the
shunt coil operates the regulating lever to bring the carbons into contact.
In this arrangement the lamps will work in a series circuit with different
currents, thus say during the beginning of the evening a twelve ampere current
can be sent through the main and later on an eight ampere current, so that the
light of a series circuit can be perfectly regulated from the electric generator, or
by restances.
In a duplex or multiplex lamp the cords conveying the current to the different
sets of carbons are separately insulated.
Dated this 20th day of June 1895.
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents.

page_text: Improvements in Electric Arc Lamps.
I WILLIAM JAMES DAVY, Engineer, of Rostrevor, Boundaries Road, Balham,
in the County of Surrey, late of 4 Parolles Road, Upper Holloway, in the County
of London 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 arc lamps relates more especially to
lamps in which the positive and negative carbon holders are connected together by
a chain or 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, but is also applicable to other
lamps, and consists of a friction surface geared to and moving with the carbon
holder, a carrier adapted to be rotated round the axis of the friction surface, a
brake shoe mounted on the carrier in close proximity to the friction surface, a
lever adapted to move the brake shoe into contact with the friction surface and
then to rotate bodily with its fulcrum about the axis of the said friction surface,
and a means for determining the position of the brake lever according to the
resistance of the arc. Preferably the pulley makes one complete revolution only
to totally consume the carbons.
In the accompanying sheet of illustrative drawings
Fig. 1 is a side sectional elevation of a single arc lamp constructed according to
this invention. Fig. 2 is a front elevation and Figs. 3 and 4 are sectional plans of
the same.
Figs. 5. 6. 7. and 8 are similar views to Figs. 1. 2. 3. and 4 showing a duplex arc
lamp constructed according to this invention.
Figs. 9. 10. 11. and 12. are detail views of the brake device, and
Figs. 13, 14, and 15 are modifications of the gripping device.
In the single arc lamp illustrated in Figs. 1-4
с
The upper carbon traveller a is guided on two parallel rods b and the lower
carbon-holder c is attached to a tail rod d secured to a traveller e guided on two
parallel rods f. The two travellers a and e are connected together by cords a¹ e²
passing over and secured to the pulley h. The pulley is mounted loosely on the
spindle i fixed in the supports . The rods and fare secured at their upper
ends in sockets in the top plate 62 of the lamp and at their lower ends in sockets
on the bottom plate and are also secured in sockets in the base disc m.
periphery of the cord pulley h is of vulcanite or similar insulating material fitted
on a flanged metallic pulley h' and the current is conveyed to the carbons through
the cords a¹ e¹.
The
The metallic pulley is hollow and a split ring o forming the carrier and made
in two parts hinged at o' fits loosely within the pulley h¹ and carries the projections o
forming the brake blocks. A brake lever n is pivoted to one free end of the split
ring o and a pin n¹ on the lever bears on the other free end of the split ring. The
downward motion of the lever is limited by the stop n². If the end of the lever n
be pulled upwards it first rotates slightly on its pivot and the pin n' acts on the
end of the ring to expand it and cause the blocks at o' to grip within the pulley h.
The pulley ring and lever are then rotated bodily round the axis of the pulley and
separate the carbons the lever being raised off its stop.
The brake lever n is operated by the link p¹ from the arm of a solenoid lever p
pivoted in the supports 13. The solenoid core s¹ of the solenoids is attached to
the other arm of the lever so that the weight of the core tends to raise the link p¹
and lever n to separate the carbons. The solenoid is arranged as a shunt to
the arc.

page_text: Normally the weight of the solenoid core raises the link p₁ and brake lever n
causing the pulley h¹ to be first gripped and then rotated to separate the carbons.
On passing the current to the lamp, the whole current tends to pass through the
solenoids which draws the core s¹ upwards. The link p and the brake lever n then
descend and the lever n comes against its stop n² and withdraws the brake blocks
from the friction surfaces and allows the carbons to feed together. The greater
portion of the current then passes through the carbons and the solenoid core ¹
falls downwards again raising the link p' and lifting the brake lever n off its stop n
and separating the carbons. The solenoid then takes up an intermediate position
according to the resistance of the arc with the lever n just resting on its stop and
withdrawing the brake shoes sufficiently to allow the pulley to rotate slowly and
regularly to feed the carbons together as they consume away. A dash pot r
serves to steady the motion.
In the duplex lamp illustrated in Figs. 5-8
are
Each upper carbon traveller a is guided on two parallel rods b and the lower
carbon holder c is attached to a tail rod d secured to a traveller e guided on the
two parallel rods b. The travellers a and e are connected together by cords passing
over and secured to the pulley h. The pulleys h are mounted loosely on the same
spindle i fixed in the pillar secured to the base disc m. The pulleys
constructed similarly to those described with reference to the single arc lamp.
The brake levers n of both sets of carbons are operated by links p¹ from the
same arm of a solenoid lever p pivoted on a horizontal axis p³ mounted in the
pillar 2. The lever p is connected to the cores s¹³ of the shunt and series
solenoids ss and the levers n normally rest on the stops n² with the carbons in
contact. On the current passing to the lamp the series solenoid s draws in its core
and strikes the arc and the shunt solenoid's acts in the usual way to steady and
regulate the length of the arc. It will be seen that in the first described arrange-
ment the weight of the core s' performs the same function as the series solenoid
and its core in the last arrangement. The core s' being drawn up by the solenoid s
causes the links p' and brake levers n to descend and the levers n come successively
against their stops and withdraw the brake blocks from the friction surfaces and
allow the carbons to feed together. The greater portion of the current then passes
through the carbons and the solenoid core s falls downwards, again raising the
links p and lifting the brake levers n successively from off their stops, and
separating the carbons, the pair last separated striking the arc. The solenoid then
takes up an intermediate position according to the resistance of the arc with one
lever n raised off its stop, and the corresponding carbons separated, and the other
lever n just resting on its stop and withdrawing the brake shoes sufficiently to
allow the pulley of the first pair of carbons to rotate slowly and regularly to feed
the carbons together as they consume away. When the first pair of carbons is
consumed the lower carbon holder tail rod comes against a stop and prevents them
feeding further together and the second lever n comes against its stop and brings
the second pair of carbons into operation. A dash pot r serves to steady the
motion.
It will be readily understood that the split ring may be replaced by any other
suitable carrier adapted to rotate round the axis of the pulley or that the brake
device may be operated by any other arrangement of solenoids.
In the modification of brake shown in Fig. 13 the lower brake block is replaced by a
friction roller o so as to reduce the friction of the brake's weight and allow a more
delicate feed.
In the modification of brake shown in Figs. 14 and 15 two brake levers teach
carrying a brake shoe t¹ in close proximity to the internal surface of the pulley h¹
are mounted loosely on a pivot v carried near the opposite internal surface of the
pulley by a carrier lever n³ mounted loosely on the spindle i. In Fig. 14 the brake
lévers t are separated to cause the shoes t¹ to grip the internal surface of the
pulley by means of the elliptical cam w pivoted to the end of the carrier lever n
and rigid with an arm w operated by the link p¹ Figs. 1 and 5.
:

page_text: In Fig. 15 the elliptical cam is replaced by the crank arms w² and links w³.
The brake mechanism is also applicable to lamps in which the carbons are fed
together or one carbon is fed against the other by toothed gearing or the like, the
friction pulley being connected by gearing to the lamp mechanism so that it is
rotated as the carbon holders are traversed.
The shunt lamps will work in a series circuit with different currents, thus say
during the beginning of the evening a twelve ampere current can be sent through
the main and later on an eight ampere current so that the light of a series circuit
can be perfectly regulated from the electric generator or by resistances.
When working a number of lamps governed by a shunt solenoid and weight, in a
series circuit by a series electric generator, in order to excite the generator a
resistance equal to the working resistance of the circuit is inserted across the
terminals of the machine and when the generator has attained the proper E.M.F.
the current is shunted across to the lamp circuit either by hand or automatically.
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 I
claim is :-
―
1. In electric arc lamps the friction device for controlling the motion of the
carbon holder consisting of a friction surface geared to and moving with the
carbon holder, a carrier adapted to be rotated round the axis of the friction surface,
a brake shoe mounted on the carrier in close proximity to the friction surface, a
lever adapted to move the brake shoe into contact with the friction surface and
then to rotate bodily with its fulcrum about the axis of the said friction surface,
and a means for determining the position of the brake lever according to the
resistance of the arc.
2. In electric arc lamps the friction device for controlling the motion of the
carbon holder consisting of a friction surface geared to and moving with the carbon
holder, a brake shoe so mounted with respect to the friction surface that when
operated it first pivots eccentrically to grip the said surface and then pivots
concentrically to move bodily with the surface, and a means for operating the
brake shoe according to the resistance of the arc.
3. In electric arc lamps the friction device for controlling the motion of the
carbon holder consisting of a friction surface geared to and moving with the carbon
holder, a split ring mounted in close proximity to the said surface, a cam lever
pivoted to one end of the split ring and adapted to act on the other end to cause
the ring to grip the surface and then move with it, and a means for operating the
cam lever according to the resistance of the arc.
4. In electric arc lamps the friction device for controlling the motion of the
carbon holder consisting of a friction surface geared to and moveing with the
carbon holder, a brake lever with brake shoe in close proximity to the friction
surface and pivoted eccentrically to the friction surface, a lever pivoted
concentrically to the friction surface and carrying the brake lever pivot, and a
means for determining the position of the brake lever according to the resistance
of the arc.
5. In electric arc lamps the friction device for controlling the motion of the
carbon holder consisting of a friction surface geared to and moving with the
carbon holder, brake shoes adapted to act in opposite directions on the said surface
to grip it and then to rotate with it, a lever cam adapted to approach or recede
the brake shoes in respect to one another to cause them to grip on the surface, and
a means for actuating the lever cam according to the resistance of the arc.
1000
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents.