Improvements in Change-over Mechanism for Electric Arc Lamps.
Year: 1892

page_text: Date of Application, 11th Apr., 1892
Complete Specification Left, 10th Jan., 1893-Accepted, 18th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in Change-over Mechanism for Electric Arc Lamps.
WILLIAM JAMES DAVY of 30 Cornwall Road Stroud Green North London,
Mechanical & Electrical Engineer, do hereby declare the nature of this invention
to be as follows:-
My invention is for improvements in the mechanism of electric arc lamps,
whereby in addition to the ordinary working parts for the striking & feeding of the
arc there is provided an arrangement or combination of suitable parts which enable
any number of pairs of carbons to be burned in succession, without intermission of
the light & by the unaided action of the mechanism of the lamp.
My invention is for mechanical & electrical combinations to be added to the
ordinary mechanism, & to be combined in such a manner as that the invention will
effect the interchange of pairs of carbons, substantially as herein described &
specified.
My invention consists of two (2) carbon holders together with suitable mechanism
for providing that when the first pair of carbons are burnt out the holders are
lifted back into their striking position, & by an automatic arrangement the two
fresh or succeeding carbons are shot into the receivers on the said carbon holders.
The said receivers are made or arranged so as automatically to receive the carbons &
to hold them in place.
The stock carbon holders, or holders for the stock of carbons are placed one at
the upper end of the top carbous the other at the lower end of the bottom carbons,
& are arranged so that they hold the carbons in such positions that there is none of
the useful light intercepted by the carbons or no shadow cast on the area to be
illuminated by the lamp.
The stock carbon holders are fixed to the frame of the lamp & are stationary,
while the working carbon holders slide towards or away from one another on
vertical guides under the action of the controlling mechanism. Each pair of
carbons as it is burnt out is succeeded by another pair which is forced from the
stock carbon holders into the working carbon holders by means of springs or other
suitable mechanism, the operation being actuated & controlled by electrical
contacts made by the working carbon holders in their descent or ascent.
I place
an electromagnet or other suitable mechanism upon the lower part of the working
carbon holder in such a manner as that by the operation of an electrical contact
the working carbon holder is held rigidly in place during the instant that the
interchange of carbons is taking place. The object & purpose of this detail of
my invention is to provide against injurious & prejudicial action by the recoil of the
operating springs.
The motions of the several parts and movable details of my invention are
actuated & controlled by the force of springs placed in suitable receptacles in the
mechanism, & by the operation of electromagnets suitably arranged so as to
actuate & control a train of wheels, clockwork, or other suitable mechanism or
combination of mechanical parts.
The whole being arranged so as to perform the operations of supplying &
inserting into the electric circuit, in an efficient & working manner, successive pairs
of carbons, viz., either two pairs or a greater number; substantially as herein
described & specified.
Dated this 11th dow of Anil 1809
WILLIAM JAMES DAVY.

page_text: COMPLETE SPECIFICATION.
Improvements in Change-over Mechanism for Electric Arc Lamps.
I, WILLIAM JAMES DAVY, late of 30 Cornwall Road Stroud Green
London N., and now of 41 Wandsworth Bridge Road Fulham London S.W.,
Mechanical and Electrical Engineer, 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:—
My invention is for improvements in the mechanism of an electric arc lamp,
whereby, in addition to the ordinary working parts for the striking and feeding of
the arc, there is provided an arrangement or combination which enables any
number of pairs of carbons to be burned in succession with very slight intermission
of the light and by the unaided action of the mechanism of the lamp. My
invention is for mechanical and electrical combinations to be added to the ordinary
mechanism.
A very important part of my invention consists in providing holders at the top
and bottom of the lamp which hold a stock of carbons in readiness to be
successively and automatically transferred to the working carbon carriers, which
carriers slide in the usual manner on vertical guides to provide for the regulation.
of the arc.
I shall hereinafter call such holders "stock carbon holders."
I also provide mechanism for effecting the successive transference of the carbons
from the stock carbon holders to the working carbon carriers when required,
mechanism for bringing the working carriers into such positions as to enable this
operation to take place, and mechanism for short circuiting the lamp while the
change over is being effected.
In describing my invention I make reference to the accompanying drawing in
which
Fig. 1 is a sectional elevation of an electric arc lamp, showing such parts as are
necessary for the purposes of this description.
Fig. 2 is a full size section of one of my stock carbon holders.
Fig. 2 is a full size section of a working carbon carrier adapted to carry one
carbon in the centre for initial burning, and to receive successive carbons from the
stock carbon holder into suitable sockets arranged round its centre.
Fig. 3 is a plan of the carbon carrier shown in section in Fig. 2^.
Fig. 4 is a plan of the mechanism attached to the stock carbon holder for
releasing successive carbons therefrom.
Fig. 5 is an elevation of part of the mechanism shown in Fig. 4.
Fig. 6 comprises (A) an elevation, and (B) an inverted plan, of mechanism for
short circuiting the lamp and putting the change over mechanism into operation
whenever the working carriers have approached within a certain distance of each
other by reason of the consumption of the burning carbons.
Figs. 7 and 8 show an alternative arrangement of mechanism to take the place
of that shown in Fig. 6.
a a' are two stock carbon holders fixed firmly to the top and bottom portions of
the frame of the lamp. These stock carbon holders hold firmly in place, ready to be
delivered into the working carbon carriers ff, four or more sets of carbons as
shown.
ff are the carbon carriers fixed firmly to rods and guides of the usual form
which are controlled by the striking and regulating mechanism in the usual manner.
Such striking and regulating mechanism may be of any approved form and it is
therefore not shown on the drawing. In the stock carbon holders are sockets c
(Figs. 1 and 2), into which the carbons are fixed firmly by suitable set-screws.
These sockets C, fit easily into recesses in the 'bottom of which are springs e (Fig. 2).
Each socket has a square tail which passes through a hole in the bottom of its
respective recess and is pierced with a key or più d which holds the socket into the

page_text: recess against the action of the spring e. There are four of these sockets fitted
into their respective recesses in the stock carbon holders shown in this drawing, but
a larger number can so be fitted. The carriers (Figs. 1, 2, and 3) are arranged
with four holes 9 tapered at their inner ends and generally shaped to receive and
fit the socket c: they are arranged exactly in line with the said sockets in the
stock carbon holders. Each hole g is fitted with a suitable spring check key h
which retains the socket c in the recess when it has been delivered thereinto.
The central recess is to hold the first carbon to be burnt, and the change over
mechanism does not therefore apply to it.
A drum (Figs. 1, 2, 4, and 5) has a bevel spur wheel quadrant upon it which gears
into the pinion n. On the back of the latter is a pall wheel operated by the pall m,
which in its turn is operated by a lever pivoted at ', and connected in a suitable
manner to the rod k. On the base of the drum i, is a three toothed disc m² (Figs. 2, 4,
and 5) the teeth of which project far enough to successively engage and withdraw from
the tailpieces of the sockets c, the keys d.. The teeth as shown on the drawing are
so pitched that all four keys a will be engaged and withdrawn whilst the disc m
only makes a fraction of a revolution. This arrangement of drum, toothed disc,
and other necessary parts for the successive release of the carbons is applied to the
top and bottom stock carbon holders of the lamp, and it is put into operation
whenever the respective carbon carrier is moved outwards towards the stock carbon
holder and engages the rod k by a suitable projection formed on such carrier. The
carriers are connected together by any of the arrangements commonly used in arc
lamps for the purpose of rendering their movements synchronous and opposite in
direction.
The mechanism above described, provides chiefly for the successive release of
the stock carbons from the stock carbon holders, and for their due delivery
into the working carbon carriers. It will now be seen that if the carrier f is
moved until it is in contact with the stock carbon holder a, and a suitable
vertical motion is thereby given to the rod, the pinion n will be revolved and
will drive round the drum i together with its three toothed disc m³, which will
in turn pull out one of the keys d and allow the spring e to drive the socket c
(carrying a carbon) from the stock carbon holder into that particular, recess y
of the carbon carrier which is opposite to the socket which is released.
I will now describe the mechanism for drawing the working carbon carriers
apart and into close proximity with the stock carbon holders; also the arrange-
ments for short circuiting the lamp during the change over operation.
Into the lower carrier f is screwed firmly a rod with a slot of suitable
length on one side thereof, and a projecting foot y on the other or opposite
side (Figs. 1 and 6). This rod v, practically forming part of the working
carbon carrier, is free when the ordinary controlling mechanism is not in
operation. p is a pulley firmly fixed to a suitable spindle on which is also a
pall wheel (Fig. 6): into this wheel gears a pall connected to the shaft t by
a lever and rod S; a lever u is also fixed to the shaft t, which lever rides in
the slot in the rod v. A short circuit switch w for short circuiting the lamp
during the change over in series working, is operated by a continuation of the
lever u: around the pulley ? passes a cord or chain with stops thereon and
having a weight O hanging freely at one end, while at the other end is a light
weight O¹ for the purpose of keeping a tension on the chain or cord. The stops on
the cord are so spaced that one stop can engage the foot y and pull it to its lowest
position before the succeeding stop passes the pulley p. The pulley may have
triangular indents cut in it as shown in Figs. 1 and 6 in order that the stops a may
engage therein as they pass over the pulley and so prevent any excessive drop of
the weight O. A small wheel Z may be placed as shown in Fig. 1, and freely
revolving on a spindle fixed to the framework of the lamp, for throwing the stop
piece out of engagement with the projecting foot y when the rod v has reached
its lowest position.
The action of the mechanism is as follows:-When the lamp is first put into

page_text: operation, the carbons occupying the central positions in the carriers are touching
at the point L and a current is switched on; the striking and regulating mechanism
come into play in the usual manner, but my mechanism remains entirely out of
action until these carbons are nearly burnt out. When this stage is reached, it is
the duty of the change over mechanism to introduce a fresh pair of carbons into
the carriers at top and bottom. The carriers are themselves near the point L
and the tail rod is up to its highest point and will have pulled up the lever u,
short circuiting the lamp by closing the switch : at the same instant, and by the
same lever acting through the rod S, the pall r, and the pall wheel Q, the
pulley p is released, allowing the weight O to descend and to draw down the rod v
by reason of one of the stops engaging in the footy. The descent of the rod
causes the lower carrier (to which it is firmly fixed), also to descend and to come in
contact with the lower stock carbon holder, the upper carrier at the same time
being raised into contact with the upper stock carbon holder by reason of the fact
that the carriers are connected so as to render their movement synchronous and
opposite as above mentioned.
When near their top and bottom positions respectively, the carriers engage the
rods by means of projections j formed on said carriers, thereby actuating the
mechanism for introducing a fresh set of carbons to the carriers as above
described.
The weight O, having for the present performed its function, the wheel Z dis-
engages it from the foot y, and at the same time the lever u, being pulled down-
wards by engaging the top of the slot a¹, breaks the short circuit switch contact
at w and reengages the pall r in the pall wheel Q stopping the further descent of
the weight. The carriers are now free to fall together by gravity in the usual
manner, and the current being established through them, the ordinary regulating
mechanism of the lamp comes into operation again and the action of my change
over mechanism is suspended until a new set of carbons is again required.
Figs. 7 and 8 are diagram sketches of an alternative arrangement for fulfilling
the aforesaid operation of moving the carbon carriers back into contact with the
stock carbon holders.
1 is an electro-magnetic switch; 3 is an electric solenoid shown in plan in Fig. 8.
When the carbons are nearly burnt out the carbon carrier f (Fig. 1) will have
worked its way up to the contact point R, and by aid of the arm 12, will make an
electrical contact with the relay wire passing around the electro-magnet 1 and
solenoid 3, the magnet will attract the switch arm of soft iron 2 upwards and
establish the main current marked X (Fig. 7), which passes through said arm of
soft iron and joins the relay current circuit on the body of the electro magnet.
The switch is thus held firmly, and the main current kept closed during the time in
which the change over is to be effected.
The current flowing through the solenoid 3 will suck in the soft iron core 4 to
which is fixed a sleeve on which is a pinion 5, the whole sliding on a shaft 6 but
prevented from turning thereon by a feather or other device. The pinion is caused
to gear into the pin 7 which in turn gears into a rack cut into the central rod 8
fixed, as before described, into the carrier f. When the sleeve and pinion 5 is
drawn into gear, an ordinary clockwork train, connected therewith through the
spindle 6, is released by the action of a small lever or brake and the clockwork
commences to revolve, lifting the carbon carriers back into contact with the stock
carbon holders. A stop or projection 9 on the carbon carrier engages a rod k
and causes the release of a fresh carbon from the stock holder, just as when a
weight was used. At the same time the top of the rod k engages the lever 10,
and, by breaking the short circuit switch contact, re-establishes the current through
the lamp. The electric solenoid becomes inoperative and the clock work is pulled
out of gear by a light spring or other suitable arrangement and its action is stopped
by the lever or brake before mentioned.
I have described mechanism in which the working carbon carriers are drawn
apart and the change over operation effected by the falling of a weight released

page_text: automatically at the proper moment. I have also described mechanism in which
the same results are obtained by clockwork which is automatically put into gear
with one of the carriers and allowed to run at the desired moment.
I will now
point out that the same arrangement of contact piece R, of rod k, lever 10, short
circuit switch 2, and electro magnet 1 (see Figs. 7 and 8), which switch a current
through the solenoid 3, may just as readily be made to switch the main current, or
a shunted portion thereof, through a small and suitable electro-motor, which, by
winding up a cord, would readily perform the work of the changing over operation
in place of the clockwork or falling weight previously described. Such a motor,
when used, may be placed in any position where it can be conveniently connected
to one of the working carbon carriers by a cord or otherwise.
By this invention an electric arc lamp may be rendered capable of working
without attention for much longer periods than heretofore and a great saving of
labour will result. Further, the sockets c may be attached to the carbons ready.
for insertion into the lamp in any workshop or other convenient place so that less:
time and skill will be required for the insertion of each carbon into its place in the
lamp than is the case when such sockets are not used.
It will be obvious that many modifications may be made in the details of this
change over mechanism without departing from the limits of this, my invention..
I may, for instance, wish to modify or control the movements of certain parts, such
as the falling weight device, by the application of a dash pot of approved form.
In the same manner I may apply wind vanes or other controlling and steadying
devices to the electro motor (when such is used), in order to prevent its too rapid
action. On the other hand, I may in some cases require to assist the action of
parts of the mechanism by means of electro magnets or solenoids deriving their
energy from the main current. Further, I do not confine myself to the use of
three teeth on the toothed disc m', since one tooth would suffice if a greater amount.
of turning movement were communicated to the dise; and, on the other hand, I
may advantageously use more than three teeth if I wish to release more than four
carbons from the stock carbon holders. A very useful equivalent for the square
tail and key d to the socket c, consists of a round tail having a collar, which tail.
and collar project far enough through the stock carbon holder to permit the edge
of a small plate, pivoted at one end, to pass under said collar, the said plate being
so placed as to be engaged and swung aside by a tooth of the disc m', thereby.
releasing the socket c. The mechanism for drawing apart the carbon carriers and
bringing them into proximity with the stock carbon holders, may be connected up.
to the top or bottom carrier as may be most convenient.
Having now particularly described and ascertained the nature of my inven-.
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. Change over mechanism for an electric arc lamp in which successive pairs of
carbons are automatically passed from stock carbon holders into the working carbon
carriers as and when required by the consumption of carbon in the lamp.
2. The use of sockets or ferrules of suitable material, substantially as described.
in reference to the socket or ferrules e in Figs. 1 and 2, for facilitating and
accelerating the trimming or manual replenishing of the lamp and for ensuring an
efficient electrical contact with the working carbon carriers when the socketed or
ferruled carbons are delivered thereinto.
3. In change over mechanism for electric arc lamps, a stock carbon holder from
which ferruled or socketed carbons are forced into working carbon carriers. by
springs, or by other equivalent means, when said socketed or ferruled carbons are.
released automatically or otherwise.
4. The combination of parts comprising the lever and ratchet arrangement k, l, m,
the pinion u, the drum and toothed quadrant i, and the toothed disc m', arranged
and operated substantially as described, for the purpose of releasing successive.
carbons from the stock carbon holders.

page_text: 5. In change over mechanism for electric arc lamps, the combination of the
lever 10 operated by the travel of the carbon carrier, the short circuit switch 2, the
electro magnet 1, all taken together and in connection with the electric circuits
shown in conjuction therewith in Fig. 7, the whole combination being put in action
by the travel of the carbon carrier or carriers for the purpose of short circuiting
the lamp during the change over and for bringing into action an electro-motor,
clockwork, or other source of energy, all substantially as described and with the
objects stated.
6. Change over mechanism for an electric arc lamp which ordinarily remains
passive, and in which the travel of a carbon carrier due to the consumption of the
active carbon, short circuits the lamp and renders active, either by mechanical or
electrical means, a source of energy such as a weight, a clockwork arrangement, or
an electro-motor, for the purpose of bringing the carriers back into proximity with
stock carbon holders and operating the releasing mechanism by which the fresh
carbons are passed from said holders to the carriers.
Dated this 7th day of January 1893.
WILLIAM JAMES DAVY,
Applicant.