Improvements in and relating to the Carbon Feeding Mechanism of Electric Arc Lamps.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in and relating to the Carbon Feeding Mechanism of
Electric Arc Lamps.
I, CHARLES WOOD, Arc Lamp Manufacturer, residing at Saint Mary's Cottage,
Chester Road, New Oscott, in the County of Warwick, do hereby declare the
nature of this invention to be as follows:-
This invention relates to that class of arc lamp in which the feed of the carbons
is primarily controlled by the shunting of the electric current through the resist-
ance becoming greater at the carbon points, and it has particular reference to
those lamps having separate electro magnets, viz.:-series and shunt, and a rota-
table brake wheel actuated by the gravitation of the carbon holders or other
means, the said brake wheel to be controlled by the mechanism intervening be-
tween it and the electro magnets.
It is in the construction and application of this intervening mechanism wherein
the invention resides, the same having for its object a uniform, gradual and
sensitive operation of the brake wheel or its equivalent.
In carrying the invention into effect I mount above the electro magnets, by
means of suitable brackets standing up or out from the arc lamps frame or bed
plate, two jointed arms or levers, one having preferably two arms and being of
the first order, and the other having but one arm and being of the third order.
These levers are jointed one above the other upon a common bracket, and are
only connected through the brake band or chain, which passes round the brake
wheel and has its respective ends connected to the said levers, and an inclined part
or projection upon the one end of the double armed lever opposite that to which
the said chain or cord is connected, and an adjustable set screw or pin mounted
vertically through the single armed lever and whose end impinges upon the said
inclined part. The said levers are so mounted in their bracket support that the
end of the set screw carried by the one, in their movement, travels up and down
upon the inclined part or projection, through the different ratios of the par-
ticular throws of their arms; the said set pin and inclined part constituting
between them the mechanism for the delicate slip and grip movement of the
chain or cord upon the brake wheel.
The levers, as aforesaid, are each independently controlled by the soft iron cores
of the series and shunt coils, the first named core being preferably connected to
the one armed lever carrying the adjustable set screw, and the last named core to
the end of the double armed lever opposite to the inclined part.
In working, the lever carrying the inclined part, when operated by the electric
magnet of the shunt coil, constitutes, through the incline and the pin, a momen-
tary tipping media to the lever carrying the set screw and rocks it, which frees the

page_text: band from the brake wheel slightly. When the current is only in the series coil
the band is pulled down onto the brake wheel's periphery against the weight of
the core of the shunt coil.
Dated this 28th day of February 1898
W. P. THOMPSON & Co.,
11, Burlington Chambers, New Street, Birmingham,
Patent Agents for the Applicant.
Improvements in and relating to the Carbon Feeding Mechanism of
Electric Arc Lamps.
I, CHARLES WOOD, Arc Lamp Manufacturer, residing at Saint Mary's Cottage,
Chester Road, New Oscott, in the County of Warwick, 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 pertains to that class of arc lamps in which the feed of the car-
bons is controlled, primarily, by the shunting of the electric current as the resist-
anea becomes greater between the carbon's points, and, secondarily, through
mechanism which intervenes between the carbons' supporting or carrying means
and the devices for shunting the current. The said invention, which consists in
certain improvements in and relating to the said intervening mechanism has
particular reference to those are lamps in which the carbon holders are suspended
indirectly from a rotatable brake wheel which is governed by them and by a slip
and grip friction band or chain controlled by the intervening mechanism before
referred to. Are lamps according to this invention have also, preferably, series
and shunt electro-magnets which perform certain direct functions in the working
of the said intervening mechanism, but the shunt magnet need not necessarily be
mechanically connected with the said mechanism, as a weight the equivalent of
its core could be used in its stead.
It is in the construction and application of this intervening mechanism before
referred to wherein the invention resides, the object attained by it in the are
lamp being a more uniform, sensitive and positive government of the brake wheel
supporting the carbons.
The method of carrying this invention into effect is illustrated by two forms of
are lamps shown in the accompanying sheets of drawings, Figs. 1, 2 and 3 show-
ing one form of the invention and Fig. 4 another form. These figs. illustrate the
first form in vertical section in Fig. 1 and 2 and in horizontal elevation, through
the intervening mechanism only, in Fig. 3. The differences in the sections
Figs. 1 and 2 are only in respect of the positions of the parts of the feed mechan-
ism, the first named fig. being the one when the arc at the carbons points has been
struck. and the last named when the separated carbon points are being fed to
each other. Fig. 4 is a similar vertical section to Fig. 1. but the working of the
intervening carbon feeding mechanism is somewhat different to the working of
that in Fig. 1.
In Fis. 1 to 3, mounted above the electro magnets g, h, which are respectively
shunt and series, by means of suitable brackets, standing up from the are
lamps frame or bed plate c. are two jointed arms or levers d, e, the first named

page_text: lever having two arms d³, d³, and being of the first order, and the last named
lever having one armed and being of the third order. These levers d, e, are
jointed independently of each other within the brackets, a, at de and are only
connected by the brake band or chain f, which passes round the brake wheel f
and a set screw or pin, i, which constitutes an adjustable stop and which is
mounted through the single armed lever, e, so that its end at certain times
impinges upon the arm of the lever d. The ends of the brake band or chain f
are connected respectively to the free end of the arm of the lever d and to
the free end of the arm e of the lever e, in such a manner that the length of
the arm from its fulcrum d to its point of connection with the brake band is
considerably less than the length of the arm e² from its fulcrum to its point of
connection with the band or chain, so that as the band or chain is paid out upon
the one side of the brake wheel and taken in upon the other equally the said levers
have different movements and ratios; this last part will be more fully described
hereinafter.
The levers d, e, are so mounted in their bracket supports that the end of the
set screw i, at a time in the movements of the said levers, travels up and down
upon the arm d³ of the lever d and enables the lever d to tip the lever e, and the
band or chain f to slightly slip the brake wheel. These levers are shown con-
trolled by the soft iron cores 2, h2, of the shunt and series electro magnets; the
first named core being connected to the extreme end of the arm d of the double
armed lever d, and the last named core being connected to the free end of the
single armed lever e. Instead of the shunt electro magnet being connected to the
end of the arm the said electro magnet may be otherwise disposed, and a
suitable weight, which will have the effect of overcoming the energy in the series
electro magnet at a particular time, applied in its stead at the end of the armi ³.
It will be clearly seen by reference to Figs. 1 and 2 that the throw or radius of the
arm from its point of connection with the brake band or cord is considerably
less than the throw or radius of the lever e from its point of connection with the
brake band or chain. This is of the utmost importance as it gives the levers d
and e different ratios. As an illustration of this: assuming the parts of the inter-
vening mechanism to be in the position shown in Fig. 1, viz. with the arc struck
between the carbons points, as the resistance becomes greater between the last
named the current passes into the shunt electro magnet g and causes its core g³
to be drawn into the coil. This rocks the lever d upon its fulcrum and moves
its arm a certain number of degrees in its radius, and pulls down or draws in
the brake band or chain f a certain distance. The said band or chain being
unstretchable, the drawing down of it upon the one side must of necessity take an
equal amount of it up unon the other side, but, as the radius of the lever e from its
point of connection with the brake band is greater than the radius of the arm &
of the lever d, the said lever e will not be moved as many degrees in its circle as
will the arm of the lever d: in consequence of this the arm of the lever d
gains upon the levere and after a time overtakes the adjustable ston i carried by
it, and immediately any further rocking of the lever d in the same direction takes
place the arm of the lever d tips the lever e and slackens the brake band upon
the brake wheel. allowing the latter a uniform slip movement for feeding forward
the carbons. This position is shown in Fig. 2. Immediately the resistance at the
carbon points is removed. the series electro magnet exerts a pulling down ten-
dency on the lever e. which, by reason of its larger throw, returns the lever d. to
its position shown in Fig. 1, in advance of its own movement, the arc being
struck in the meantime.
With reference to Fig. 4, the throws or radii of the arms d. e3 of the levers d
and from their noints of connection with the brake band or chain fare exactly
equal, so that if the lever d is moved a certain number of decrees in its radius
the lever e will be moved exactly the same number of degrees in its radius. The

page_text: tipping of the arm of the lever eª, in order to slacken the band or chain and slip
the brake wheel, is brought about in this instance by an inclined rigid part d
carried upon the end of the arm d³ of the lever d. This inclined part, after a
certain amount of rocking of the levers, will overtake the end of the adjustable
stop and tip the lever e by forcing the said stop up the slope of it.
Thus it will be seen that the double armed lever d, having a different ratio to
the lever e, and the adjustable stop i in the one form of intervening mechanism,
and the equal ratio double armed lever, the inclined part, and the adjustable stop
in the other form of intervening mechanism, constitute each a momentary tip
ping medium to the lever e; the said tipping slightly freeing the brake band
or chain from the brake wheel's periphery and allowing a gradual and uniform
slip of the said wheel.
In both forms of tipping media described, the stop i is necessarily an adjustable
one in order to compensate for any differences which may occur in the length of
the brake band or chain, and also to adjust the respective movements of the
levers for striking the arc.
It will be evident from Figs. 1 and 2 that the timing of the tipping of the
levere by the arm d³ of the lever d can be varied by either lengthening or short-
ening the throw of the said arm; or instead of this the stop i can be adjusted
along the said lever with the same result.
In both forms of arc lamps shown, the holders which carry the carbons are sus-
pended indirectly from the brake wheel f³, so as to exert a rotating tendency
thereon, by means of cords f³ and pullies f the last named being mounted upon
the axis f5 of the brake wheel.
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
First. In an electric arc lamp, the combination of the parts f, f³, of the car-
bons' suspending means, or their equivalents, a pair of levers or rocker bars so
fulcrumed to the arc lamp's frame and connected to the terminations of the
brake band or chain, f, that the lever d, which is a double armed one, has a
smaller radius from its point of connection with the brake band
or chain
than has the lever e from its point of connection with the brake band
or chain, and which said lever d constitutes at a certain period in the
carbon's feed a tipping medium to the lever e for the purpose of momentarily
freeing the brake wheel to free the carbons and the electrical devices such as g, ga
and h, ha for controlling the rocking of the levers d and e, substantially as de-
scribed and set forth in Figs. 1 to 3.
Second. In an electric arc lamp, the combination of a brake wheel f², from
which the carbons are suspended, a brake band f in frictional contact with the said
brake wheel, a pair of levers or rocker bars d, e, having respectively double and
single arms, and which have the terminations of the brake band or cord so con-
nected to them that the said levers have different ratios and unequal degrees of
movement relative to the movement of the band, in order that the lever d shall
constitute a tipping media to the lever e, a series electro magnet h, h³, connected
to the lever e for partly controlling the levers e and d, a shunt electro magnet, or
its equivalent, g g connected to the lever d also for partly controlling the move-
ment of the levers d and e, and an adjustable stop i carried by the lever e, sub-
stantially as described and set forth in Figs. 1 to 3.
Third. In an electric arc lamp, the combination of the carbons suspending
means f, f and f³, equal radius levers or rocker bars d, e, fulcrummed one below
the other and which are connected to the terminations of the band or chain f,
the one lever d, which is a double armed one, carrying an inclined part d, and the
other lever e, which is a single armed one, carrying an adjustable stop i to form

page_text: a tipping media to the lever e for freeing the band f, and series and shunt electro
magnets g,g, and h³, substantially as set forth in Fig. 4.
Dated this 20th day of July 1898.
W. P. THOMPSON & Co.,
11, Burlington Chambers, New Street, Birmingham.
Also of Liverpool, London and Manchester,
Patent Agents for the Applicant.