IMPROVEMENTS IN ELECTRIC ARC LAMPS
Year: 1884

page_text: COMPLETE SPECIFICATION.
"I
I HAMILTON WELDON PENDRED, Civil Engineer of Crohill, Angles Road,
Streatham in the County of Surrey do hereby declare the nature of my.
Invention for IMPROVEMENTS 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 :-
•
My Lamp is of that type in which the upper carbon Holder descending by its
own weight brings the upper carbon nearer to the lower carbon as both are
consumed in such a way that the arc is maintained approximately of the same
length. The descent of the upper carbon is controled by wheels and a fan or fly,-
and a brake or detent. These wheels and fan or fly, brake or detent, are mounted
in a frame or "cage," which which swings on centres concentric with those of one
of the herein before mentioned wheels. On the axis of this wheel may be fitted a
pinion gearing into a rack on the upper carbon holder, so that the movement of the
said carbon holder will cause that of the wheel, but I prefer to fit on the axis of
the said wheel a small roller round which is wound a cord. The lower end of this'
cord is secured to the upper carbon holder near its lower end, and the upper end of
the cord is secured to a tension spring hooked to the upper carbon holder near the
top, said tension spring serves to keep the cord tight and prevent it from slipping
on the roller. The cord and roller are the equivalent of a rack and pinion but
work more smoothly.
The wheel before mentioned, which I call the great wheel is mounted loose on
the axis, and is caused to revolve with it in one direction by a ratchet wheel and
click. When the upper carbon is raised by hand the teeth of the ratchet wheel'
pass freely under the click; and the wheels and By or brake wheel here in before
mentioned are put in motion or driven by this ratchet wheel and click..
Under one end of the here in before mentioned frame or cage I fix a solenoid in
the main circuit, and I suspend the core of the said solenoid from the frame or
cage. Thus as the core rises or falls in the solenoid the frame or cage will swing on
its centres which are concentric with those of the great wheel. In any convenient'
position I fix a stop against which the brake or detent rests, when the before
mentioned solenoid core has been partly withdrawn from the solenoid.. The
contact of the brake or detent with the said stop releases the wheels in the cage;
and permits the descent of the upper carbon holder. Lamps thus constructed may
be worked in multiple are or singly.
When my lamps are to be worked in series. I add a high resistance coil on
shunt circuit, which coil takes the form of an electro magnet, and opperates to take

page_text: the brake or detent herein before mentioned off, so releasing the great wheel and
permitting the descent of the upper carbon holder whenever sufficient current is
shunted into the electro magnet.
is a
Figure 1 of the acompanying drawings is a front elevation, and figure 2 a plan
of so much of an electric are lamp as my invention applies to. A figure
loop or ring by which the lamp may be suspended. B is a tube, shown broken for
convenience, by which the upper carbon holder A' by preference a brass tube, is
protected when raised. C.C¹ is a box of cast Iron or brass, containing the
mechanism. D D' are two binding screws into which the positive and negative
-"leads" are secured. D¹ is insulated from the body of the lamp in any way 1
convenient, as for example by insulite washers D. E is a brush or spring by
which the current of electricity is conveyed from the binding screw D into the top
carbon holder. F is a solenoid in the main circuit. G G are two rods screwed
into the box C C, which rods carry the lower carbon holder, which is insulated
from the rods. This carbon holder is not shown in the drawing and may be of 1
any convenient construction. His a portion of a wire which unites the lower
carbon holder with the solenoid or coil F. The other end of the coil F is in
electrical contact with D¹. The current entering the lamp at D passes down the
upper carbonholder and carbon, traverses the arc. enters the lower carbon, and
carbon holder, and thence rising through the wire H traverses the solenoid F and
leaves the lamp by D¹.
'
The great wheel of the train is shown at J the ratchet wheel on its axis at J', the
click at J. The roller before mentioned at I and the cord at K, the tension spring
at L. The swinging frame or cage M M Figures 2 & 3 is made of two cheeks or
plates of brass secured to each other by pillars and screws N N°. The fly train
consists of the great wheel J the second wheel O and the brake wheel or fly P.
with their respective axles and pinion. The brake wheel should make about
150 revolutions for one of the great wheel J, but I do not confine myself to these
numbers. The cage M M¹ is carried as shown more clearly in figures 2 & 3 on
prolongations of the pivots of the axle of J. which pivots are supported in
brackets QQ secured to the top of the box C C as shown. R is a high resistance
(180 to 300 ohms) electro magnet, one end of its wire is secured to the box C C in
any convenient way, the other end is in electrical contact with D¹. The whole
box CC is in the main circuit, D not being insulated from CC. To one of the
cheeks of the cage M M¹ is fixed a stud S¹ Figures 1 & 2 on which is mounted the
tubular axis of the brake T. The brake has a curved tail V on which is fixed a
small armature of soft Iron U figure 1. The tail V-is curved as shown. The end
of it, Y, comes into contact with the stop Z figure 1. when the outer end 1 of the
cage M M¹ descends far enough, and so takes the brake off the fly P as here in
before mentioned. On the curved tail V can be traversed a ring 2 to which is 4
booked one end of the tension +pring 3 the other end of which spring is fastened
to a stud 4 in the cheekplate M figures 1 & 2 This spring keeps the brake T
pressed against the fly P unless the tail V is moved by the electro magnet R
attracting the armature U with sufficient force to overcome the tension of the
spring 8 or by the here in before described action of the stop Z. 5 is a dash pot
with a loose piston plate 6 and a thin rod 7 passing nearly air tight through the
lid 8. The dash pot may be charged with a mixture of spirit and water which
will not freeze. 9 is the core, by preference hollow, of the solenoid F, its weight is
such that the end 1 of the cage M M¹ overbalances it, and draws it up out of the
solenoid unless the attraction due to the passage of the main circuit current is 8
strong enough to draw the core 9 into the solenoid. 10 is a screwed rod pivotted
to the core 9 and passing through a bracket 11. The thumb screw 12 permits the
position of the core 9 to be adjusted, 13. 14 & 15 figure 1 shew two stops and a
thumb screw whereby the range of swing of the cage M M may be determined.
The power of the spring 3 on the rake is adjusted by moving the ring 2 along 5
the curved tail V so as to give the spring greater or smaller leverage on the brake
and armature in a way which will be readily understood.

page_text: When great sensitiveness of action is wanted, I apply the brake T not to the
fly P but in the way shown in figure 4. In this modification the second wheel O
is mounted loose on the axle, on the axle is fixed a brake wheel a in which is a
pin b. In the wheel O is fixed another pin c hetween these pins is interposed a
light spring & a third pin e in the brake wheel a entering the space between the
spokes of O prevents the spring d from being strained too far open. The action
of this arrangement is as follows. When the brake T is taken off the wheel a as
herein before described the wheel being retarded only by the small resistance of
the spring & jumps round and lets the top carbon holder fall quickly, until the two
pins 6 & c come into contact. Its further motion is then checked until the inertia
of O and P is overcome when the carbon holder will continue to fall slowly until
the arc is restored and the brake reapplied. The spring d will then continue to
propel the fly P and wheel O until the pins b & c are far enough apart to permit
the brake wheel a to jump forward again as above described when the brake is
next taken off. The proportions adopted in making the lamp should be such that
the upper carbon holder can fall about of an inch before it is arrested by the
pins b&o coming into contact.
The action of the lamp is as follows When the carbons are put in, the end 1 of
the cage being heavier than the end carrying the solenoid core, will fall and the tail
end Y figure 1 of the brake T coming against the stop Z the brake will be released
as herein before described, and the wheels being free to revolve the top carbon
holder will descend until the top and bottom carbons are in contact, as soon as
a sufficient current, say one of 9 amperes with an electro motive force of 45 volts.,
passes through the lamp. The solenoid F will "suck" the core 9 into it, and
cause the cage M M¹ with the train of wheels and brake to swing round like the
beam of a pair of scales on the pivots of the great wheel, but the moment Y
leaves Z the brake is applied to the fly P and all the train of wheels being then
locked. the whole system will turn round the centre of the great wheel, carrying
the said great wheel J with it, consequently the Top carbon holder will be wound
up far enough to strike the arc. As the lamp burns and the carbons waste, the
resistance of the are will augment and the solenoid gradually losing its attractive
force the core 9 will rise slowly in it, and permit the cage M M' to swing back
toward its original position. The upper carbon will obviously participate in this
motion and descending will restore the arc. The armature U on the tail of the
brake, will now be brought within the range of the attractive power of the
magnet R. As soon as the resistance of the arc is further increased, the attractive
force of Rovercomes the resistance of the spring 3. The brake is realeased and the
lamp feeds, until the current is sufficiently restored in the main circuit to weaken
that in R enough to permit the spring 3 to overcome the attraction of R. and apply
the brake again. If the current is steady and the lamp properly adjusted this
action will be repeated as required, the cage remaining almost at rest. If any over
feeding should take place. the current will be restored sufficiently to suck in the
core 9 into the solenoid F so far that the armature U will be taken out of the
influence of R. and the upper carbon will at the same time be raised a little, and
the arc lengthened. If feeding in the way just described should not take place
from any cause, then the current in the solenoid F becoming too weak the cage
would rise far enough bring Y against Z when the brake would be taken off and
the carbon would descend as here in before described. To prevent the lamp from
feeding until the cage or frame M M¹ is in the proper position I put a pin 16
Figure 1 into the top of the case or box CC and another pin 17 into the brake
wheel or fly P These two pins prevent the revolution of the fly until it is carried
so far down by the movement of the cage M M' as herein before described that the
pins clear each other.
Figure 5 shows a modification by which the cord K may be put inside the upper
carbon holder. This holder is slotted the slot being wide enough to almit a
portion of the roller 1 as shewn. The lamp shewn in the acompanying drawings

page_text: Fig. 1. 2 & 3 is intended to be worked in series. When worked singly or in multiple
arc the electro magnet R and the armature U may be dispensed with.
The drawings shew a lamp full size but I do not confine myself to the precise
arrangement of parts or dimensions set forth in the said drawings.
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 cage or frame M M¹ swinging on centres concentric with those of a
roller or pinion carrying the upper carbon holder in electric are lamps substantially
as set forth in Figures 1. 2 & 3 as and for the purposes described.
Second. I claim. The combination of a solenoid, and its core, in the main circuit,
with a swinging frame or cage substantially as set forth in figures 1 & 2, as and
for the purposes described.
Third. I claim. The curved brake tail V, and sliding attachment 2 as a means of
altering the power of the spring 8 in an electric are lamp substantially as set forth
in fig. 1 & 2.
Four. I claim the combination of a brake wheel a Figure 4 with the train
wheel O and spring & substantially as and for the purpose described.
Dated this Thirteenth day of February 1884.