Improvements in Electric Arc Lamps.
Year: 1896

page_text: Improvements in Electric Arc Lamps.
I WILLIAM JAMES DAVY, Engineer, of Rostrevor, Boundaries Road, Balham,
in the County of Surrey, do hereby declare the nature of this invention to be as
follows:-
This invention for improvements in electric are lamps relates to lamps in which
the carbons tend to approach one another by gravity and has for its object to
control the motion of the carbon holders in a thoroughly efficient and reliable
manner and so that the same lamp shall be applicable for alternating and continuous
circuits and for different potentials.
A controlling device for an arc lamp constructed according to this invention
consists of a friction surface geared to and running with the carbon holder, a brake
shoe adapted to be forced against the friction surface, a compound controlling lever
adapted to move the brake shoe against the friction surface and then to rotate the
shoe and surface together, and a means for determining the position of the controlling
lever according to the resistance of the arc.
In one method of carrying out this invention the carbon holders are con jecte.
by separate chains or cords passing over and secured to separate pulleys rigidly
connected together and mounted on the same axis. The compound pulley is
provided with an internal cylindrical surface in which fits loosely a split spring or
hinged ring carrying brake blocks. One lever operated according to the resistance
of the arc is fulcrumed on one end of the split ring and the other lever is fulcrumed
on the other end of the split ring and bears at one end on an extension from the
first end of the split ring and is operated by the first lever. The first lever is
provided with a projection bearing on its reverse motion under the second lever.
A stop limits the motion of the levers.
It will readily be seen that whilst the force operating the compound lever to
rotate it round with the friction surface remains the same as with a simple lever
the force tending to open the split ring and thus apply the brake is increased many
times.
Dated this 11th day of May 1896
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents.
J, WILLIAM JAMES DAVY, Engineer, of Rostrevor, Boundaries Ral, Balhan,
in the County of Surrey, 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 lamps in which

page_text: the carbons tend to approach one another by gravity and has for its object to
control the motion of the carbon holders in a thoroughly efficient and reliable
manner and so that the same lamp shall be applicable for alternating and continuous
circuits and for different potentials by merely altering the controlling coils.
A controlling device for an arc lamp constructed according to this invention
consists of a friction surface geared to and running with the carbon holder, a brake
shoe adapted to be forced against the friction surface, a compound controlling lever
adapted to move the brake shoe against the friction surface and then to rotate the
shoe and surface together and a means for determining the position of the controlling
lever according to the resistance of the arc.
In one method of carrying out this invention the carbon holders are connected
by separate chains or cords passing over and secured to separate pulleys rigidly
connected together and mounted on the same axis. The compound pulley is
provided with an internal cylindrical surface in which fits loosely a split spring or
hinged ring carrying brake blocks. One lever, operated according to the resistance
of the arc is fulcrumed on one end of the hinged ring carrying the brake shoes and
the other lever is fulcrumed on the other end and bears at one end on; an extension
from the first end of the split ring and is operated by the first lever. A pin
controlled by a stop limits the motion of the levers. It will readily be seen that
whilst the force operating the compound lever to rotate it round with the friction
surface remains the same as with a simple lever, the force tending to open the split
ring and thus apply the brake is increased many times.
In the accompanying sheet of illustrative drawings:
Fig. 1 is a side sectional elevation of an arc lamp showing the compound
controlling lever constructed according to this invention.
Fig. 2 is a side elevation to a larger scale showing the compound controlling lever
and the hinged ring carrying the brake shoes and on which it operates and
Fig. 3 is a similar view to Fig. 2 showing a slightly different leverage for the
compound lever.
The solenoid lever p is connected by the links to the controlling lever n
fulcrumed to the lower half of the hinged ring o carrying the brake shoes. The
reinforcing lever n is fulcrumed to the upper half of the split ring o.. The lower
half of the split ring o is formed with an inwardly projecting extension of. The
downward motion of the compound controlling lever is limited by the stop pin n
coming on the stop n which is fixed to the frame of the lamp. The operation is
as follows:-
If the links be raised, the controlling lever acts on the outer end n of the
reinforcing lever to first force its inner end against the extension of on the lower
end of the split ring and then to open the hinged ring o to force the brake shoes
into contact with the friction surface of the cord pulleys. It will readily be seen
that the force operating to open the ring depends on the pressures on the
fulcrums 7n and on the extension of and that by suitably adjusting the leverages
this force can be increased to any extent as the pressure on the fulcrums is the sum
of the pressures on the ends of the lever. This insures that the brake blocks are
forced firmly into contact with the friction surfaces of the pulley and that there is
no liability of the parts in contact to seize or bind. When the brake blocks are
firmly in contact with the friction surface the compound lever acts as a whole and
exactly similar to a simple controlling lever. When the link s descends, pin is
lowered on to the stop n' and the brake blocks are withdrawn from the friction
surfaces. A small movement of the end of the reinforcing lever causes a quick
and almost corresponding movement of the inner end thus quickly replacing the
grip of the brake after a momentary slackening.
In one arrangement the controlling lever n is operated by the links from the
arm of a solenoid lever p pivotted in the supports p. The solenoid core p² of the
solenoids is attached to the other arm of the lever so that the weight of the core
tends to raise the links and lever n to separate the carbons. Normally the weight
of the solenoid core raises the link s and brake lever n causing the pulley to be

page_text: 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 p upwards. The links and the controlling lever n then descend and the pin n³
comes against its stop n' 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 p' falls downwards again raising
the links and lifting the controlling lever raises the whole off the stop n³ and
separating the carbons. The solenoid core p' then takes up an intermediate position
according to the resistance of the arc with the pin n' just resting on its stop n' and
withdrawing the brake shoes sufficiently to allow the pulley to rotate slowly and
regularly to feed the carbons together as they consume away.
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 in which the motion of the carbons is controlled by a
friction device operated by the opening or closing together of two parts, a compound
controlling lever for opening or closing the two parts consisting of a controlling
lever fulcrumed to one part and a reinforcing lever fulcrumed to the other part
and adapted to be operated by the controlling lever.
2. In electric arc lamps in which the motion of the carbons is controlled by a
friction device operated by the opening or closing together of two parts, the
compound controlling lever for opening or closing the two parts substantially as
described with reference to the drawings.
Dated this 11th day of February 1897.
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents..