IMPROVE- MENTS IN ELECTRIC ARC LAMPS
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I, ALFRED PRANNKUCHE, civil engineer and electrician of New York U.S.A.
(P.O. Box 2185), at present of 27 Gaisford Street, Kentish Town N.W. in the
county of Middlesex do hereby declare the nature of my invention for "IMPROVE-
MENTS IN ELECTRIC ARC LAMPS " to be as follows:-
For the purpose of obtaining simplicity in the construction of an electric arc
lamp as well as certainty in its action, I use a compound or double clutch, capable
of gripping the rod of the carbon holder, or it may be the carbon only, to lift it
when the arc is to be struck, and also to pull it downward or forward when the
length of the arc requires to be adjusted in consequence of the burning away of
the carbon.
This clutch is composed of two halves or parts, each provided with a knife edge
to press against the rod or carbon. These two parts are set one above the other on
opposite sides of the rod and are jointed or binged together by short connecting
pieces.
To each of the free ends of this clutch, a soft iron armature is fixed. One of
these armatures is set beneath the poles of an electro magnet in the main circuit,
and the other is set over the poles of an electro magnet in a shunt circuit. This is
according to one arrangement of the parts; but it is obvious that other arrange-
ments of the parts may be adapted.
When the current is put on, the main electro magnet attracts its armature and
the clutch is lifted with the rod, or carbon, which it grips, and the arc is struck.
As the carbons burn away and the resistance of the are becomes greater, the pull of
the shunt electro magnet upon its armature increases till it draws the armature
down, and with it the clutch and the rod or carbon which it grips.
This part of the clutch is counter weighted on the opposite side of the rod or
carbon, to cause the armature to ascend and resume its original position when the
shunt electro magnet lets go its hold upon it. It is obvious that a spring might
be used for this purpose instead of a weight.
To make the electro magnet let go its hold upon this armature after the
latter has been drawn down, and the carbon thereby fed forward, I wind upon the
magnet cores a second coil of wire in the direction contrary to the first, and I
connect one end of this counter coil to a kind of switch or contact maker (or it may
be a contact breaker) A small connecting rod, or an equivalent device, connects

page_text: the armature with this switch so that when the armature is down upon the poles
of the magnet, the switch is put on and a portion of the shunt current is made to
flow through the counter coil. The magnetisms being thus neutralized, the counter
weight raises the armature, which then assumes its original position and is ready
for the next stroke. The connecting rod is provided with a slot or notch so that
the switch is moved only towards the end of the stroke of the armature; that is
the counter current is put on just before the armature has completed its downward
stroke and left on till the armature has nearly resumed its original position. By
this means a full stroke of the armature is secured. Without this arrangement of
the slot the armature would merely vibrate.
When the current is shut off from the lamp the whole clutch drops, and letting
go its hold on the rod or carbon, allows the rod or carbon to fall freely.
Dated this twentieth day of Sentember 1884.

page_text: COMPLETE SPECIFICATION,
I, ALFRED PFANNKUCHE, Civil Engineer & Electrician of New York, U.S.A.
(P.O. Box 2185) at present of 27 Gaisford Street, Kentish Town, N.W. in the
County of Middlesex do hereby declare the nature of said invention for "IMPROVE
MENTS IN ELECTRIC ARC LAMPS" and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement:-
According to this Invention and for the purpose of obtaining simplicity in the
construction of an electric arc lamp as well as certainty in its action, I use a com-
pound or double clutch capable of gripping the rod of the carbon holder to lift it
when the arc is to be struck and also to pull or feed it downward or forward when
the length of the arc requires to be adjusted in consequence of the burning away of
the carbon. In connection with the clutch I use an electromagnet in the main
circuit and an electromagnet in a shunt circuit and a controlling or counter coil or
equivalent device such as resistance coil for the purpose of controlling the move-
ment of the feed armature in combination with a mechanism having a lost or dead
motion for maintaining or for breaking the controlling circuit during a predetermined
or greater part of the time that the feed armature is required to be in motion.
And in order that my invention may be more fully understood I will describe
the same with reference to the accompanying drawing which illustrates one form
of construction, Figure 1 being a sectional front elevation of the lamp and Figure 2
a sectional plan.
A is the rod or holder for the upper or movable carbon, B the electromagnet (or
it might be a solenoid) in the main circuit and C its armature which: latter can
work easily up and down on the pole screws B'. This armature is by means of
screw C¹ loosely connected to the upper half or limb D of the clutch.
E is the shunt electromagnet (or it might be a solenoid) and F its armature
which latter can work easily up and down on the pole screws El. To this
armature is fixed by means of a screw F¹ the lower half or limb G of the clutch.
The limbs D and G of the clutch are jointed by an arm D¹ from the limb D or by
a connecting link jointed at each end. Where the limbs D and G of the clutch act
against the carbon holder A they are formed with a blunt knife edge so as to grip
the rod such gripping edge being formed on the plates d and g secured to the limbs D
and G of the clutch. To the armature F and limb G is fixed a connecting rod H or
equivalent device which is formed with a slot at its upper end that takes onto a switch
lever I which turns on the fulcrum I' which is made large like the joint of a pair of
compasses so as to move with some friction so that it will stay in any position. At
its other end; this lever I is provided with a contact screw I. This latter can
make contact with a contact K which is insulated from a bracket L fixed to the
bottom of the foundation plate M of the lamp. The armature F has a counter-
weight F for pulling it down. The contact K is by a wire K¹ connected with a
second or counter coil of wire wound upon the cores of the shunt electromagnet E
but in the contrary direction of the first or shunt coil. The purpose of this counter
coil current is to cause the electromagnet E to let go its armature F after the
latter has been drawn up and the carbon thereby fed downward or forward.
N is the negative binding screw or terminal and P the positive terminal. The
shunt wire n and the countercoil wire o connect the negative terminal N with the

page_text: coils on the shunt electromagnet E. The other end p of the shunt coil wire to
one of the checks of the coil E. The action of the arrangement is as follows:
when the lamp is started the main current will attract the armature C of the main
magnet B and start the arc. As the carbons burn away and the resistance of the
arc becomes greater the pull of the shunt magnet E attracts its armature F whereby
the clutch is made to feed the rod A down. The counterweight F* causes the
armature F to descend and resume its original position when the shunt electro-
magnet lets go its hold upon it. It is obvious that a spring might be used for this
purpose instead of a weight. As the armature F is drawn up against the poles of
the magnet E the connecting rod H will lift the switch lever I make contact
between the points I' and K and thus cause a current to flow through the counter
coil by way, of K₁ and o to the negative terminal N. The magnetism of the shunt
coil being thus sufficiently neutralized, the armature F will drop assisted by the
counterweight F and assume its original position and is ready for the next stroke.
The connecting rod H is provided with a slot as shewn or a notch so that the
switch is moved only towards the end of the stroke of the armature F, bearing in
mind that the joint I' is rather stiff so that the lever I will not move from any
previous position except when impelled by the rod H. Thus the contact is made
at 1 and the counter current put on just before the armature F has completed its
upward stroke and will be left on till the armature has nearly resumed its original
position. By this means a full stroke of the armature is secured. Without this
arrangement of the slot at the top of the rod H the armature F would merely
vibrate.
When the current is shut off from the lamp the whole clutch drops against the
stop and letting go its hold on the rod allows the latter to fall freely.
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: The use in an electric arc lamp of the herein described compound or
double clutch having its two connected parts arranged at different-heights whereby
both the arc is struck and the feed of the carbon is subsequently effected
substantially as described and also as shown on the drawing.
Second-The use in an electric arc lamp of a mechanical device having a dead
or lost motion for maintaining. or for breaking a controlling circuit during a
predetermined part of the time that the shunt or feed armature is required to be
in motion for the purpose of enabling it to make a sufficient length of stroke,
substantially as described and also as shown on the drawing.
Third: An arc lamp consisting mainly of a double compound clutch such as
described, an electromagnet in the main circuit for striking the arc, an electromagnet
in a shunt circuit for effecting the feed of the carbon, a counter coil or equivalent
device for controlling the movement of the feed armature and a mechanical device
for maintaining or for breaking the controlling circuit during a predetermined part
of the time that the shunt or feed armature is required to be in motion substantially
as described with reference to the accompanying drawings.
Dated this 22nd day of June 1885
BREWER & JENSEN,
For the Applicant.