Improvements in Electric Arc Lamps.
Year: 1899

page_text: Date of Application, 1st Aug., 1899
Complete Specification Left, 1st May, 1900-Accepted, 2nd June, 1900
PROVISIONAL SPECIFICATION.
Improvements in Electric Arc Lamps.
We, CROMPTON & COMPANY LIMITED, of Arc Works, Chelmsford, in the
County of Essex, Electric Light Engineers, ARTHUR JOIN HODGSON, of 19,
Hamlet Road Chelmsford aforesaid, Electrical Engineer, and CHARLES FRANKLIN
TUBBS, of "Rosebank" Moulsham Street, Chelmsford aforesaid, Electrical
Engineer, both in the employ of the said Company, do hereby declare the nature
of this invention to be as follows:-
―:
Our improvements have for their object the simplification and cheapening of
the manufacture of arc lamps and are equally applicable to continuous current
open arc lamps, alternate current open are lamps, continuous current enclosed arc
lamps and alternate current enclosed arc lamps, and to any of the above classes
of are lamps, no matter whether the regulation is effected by the shunt winding
or by a series winding or by both a shunt and series winding.
The essential features of our new are lamps are the following and consist of
a base plate having one or more flanges and four vertical tubes attached to it,
the position of these tubes when seen in plan view is, preferably 90 degrees
apart, two of them passing right through the base plate, the other two do not.
These tubes accordingly form a guide or a support for the lower portion of the
lamp as well as four pedestals above the base plate which serve to support
the mechanism.
Through the base plate there also passes approximately in a central position
a vertical metal tube which contains the carbon with its holder and spring con-
tact similar to that described in the Specification of Letters Patent No. 6276
dated March 10, 1897 granted to R. E. B. Crompton and E. A. N. Pochin. At
the bottom of this tube we prefer to attach the clutch or feeding device and at
the top of it we secure the piston or plunger of the dash pot.
The four tubes are braced together at their upper ends by suitable castings
which also serve to support the dash pot, and a prolongation of them also serves
to support a choking coil, transformer, resistance or other equivalent device which
may be found necessary in practice to control and regulate the lamp, these tubes
also scrve to hold the outside cover of the lamp, the pair of tubes which extend
downwards from the base support at their lower ends an insulated cross piece
which carries the inner or are enclosing globe, preferably by means of a gland
or stuffing box, provided with packing of a suitable material such as is commonly
used where a tight joint is required and where the temperature is somewhat
high.
Into this cross piece is screwed the lower carbon holder, the form which we
prefer for this consists of a split tube having a thread cut upon its outer surface,
a portion of this thread is screwed into a threaded cap which contains mica
washers and to this also we are able to secure an insulated head screw which
serves to hold the outer globe in position, this outer globe is attached to a

page_text: tapped stud connected with a cross piece and two upright rods which pass tele-
scopically within the pair of lower tubes and so allow the outer globe to be raised
and lowered by these rods sliding up and down within' the tubes.
The inner globe is fitted with an air excluding cap through which the upper
carbon passes, this cap also serves as a fixed point on which the finger of a cone
shaped pivotting piece, acting as a clutch for preventing or permitting the feed
of the carbon, can rest, whenever it is desired that this clutch should come into
action and the carbon be allowed to feed downwards through the tube.
For controlling the feed of the, carbon we employ two vertical solenoids fixed
to the above mentioned vertical tubes or rods with their axes parallel to one
another and vertical. These two solenoids contain iron cores capable of motion
up and down vertically within them. The lower ends of these iron cores are
connected one with another through suitable links to a horizontal rocking lever
pivotted on a horizontal axis at or near its centre and on the base plate above
imentioned and in such a manner that when one iron core moves up (being
drawn into its solenoid) the other core is pulled down.
To the central tube containing the carbon holder and carbon is attached
rigidly an arm projecting from it at a right angle and engaging with one of the
above mentioned iron cores in such a manner that as this iron core rises or falls
the central tube is raised or lowered with it and to the same extent.
In the case of a differentially wound are lamp in which the regulation is
effected both by a series and a shunt winding, one of the solenoids is wound with
a series winding, the other with a shunt winding. The arm projecting from the
central tube engages with the iron core of the series wound solenoid, and the
solenoid windings are proportioned so that when the lamp is switched on, this
iron core is drawn up into its solenoid in spite of the counter pull of the shunt
wound solenoid on its core, and by so doing it raises the central tube with the
carbon and so strikes the arc. The regulation of the lamp will now be carried on
both by the shunt and series winding in the well known manner common to all
differentially wound are lamps. In the case of a series or shunt wound arc lamp
we either dispense with the winding on one of the solenoids and substitute for
the iron core of that solenoid a balance weight, or we wind both solenoids with
a shunt or series winding as the case may be and arrange the iron cores so that
one solenoid draws its iron core upwards and the other solenoid draws its iron
core downwards with the result that both solenoids assist one another in moving
the above mentioned rocking lever one way or the other and therefore in raising
or lowering the central tube containing the carbon.
The arm projecting from the central tube must be attached to whichever iron
core moves upwards when the current is switched on to the lamp.
In a modified form of this improved arc lamp we arrange the rocking lever
immediately above the solenoid instead of below, pivotting it on any convenient
support attached to the upper part of the lamp.
The various modifications of solenoid windings and iron cores and the use of
counterweights as above mentioned are equally applicable to this modification.
It is usual in lamps of this class to attach a dash pot. In our improved lamp
we prefer to make this dash pot an air dash pot and one method of arranging it
is to fix the cylinder of the dash pot to the upper part of the lamp centrally over
the central tube as mentioned above, and at such a height that the piston of the
dash pot which is attached to the top of the central tube can move vertically up
and down within the cylinder as the central tube moves up and down. We some-
times prefer to fix the cylinder of the dash pot coaxially with one or other of
the solenoids and immediately above or below it attaching the piston of the dash
pot to the iron core of the solenoid in question.
Another alternative is to attach the cylinder of the dash pot to the base or to
the upper part of the lamp with its axis parallel with the central tube and to
attach the piston of the dash pot to a short vertical rod attached to an arm pro-
jecting from the central tube or other moving part so that as the central tube

page_text: moves up and down the piston also moves up and down within the dash pot
cylinder.
In this case also the positions of the dash pot cylinder and piston may be
reversed if desired, the piston being fixed to the base of the lamp and the cylinder
to the central tube or other moving part and moving up and down with it.
Instead of permitting the clutch to act by resting on the air excluding cap
of the inner globe we sometimes prefer to provide a separate and independent
fixed point for the clutch to rest on.
Dated the 1st day of Jugust 1800.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.
Improvements in Electric Arc Lamps.
We, CROMPTON & COMPANY LIMITED, of Arc Works, Chelmsford, in the
County of Essex, Electric Light Engineers, ARTHUR JOHN HODGSON, of 19,
Hamlet Road Chelmsford aforesaid, Electrical Engineer, and CHARLES FRANKLIN
TUBBS, of "Rosebank" Moulsham Street, Chelmsford aforesaid, Electrical
Engineer, both in the employ of the said Company, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particu-
larly described and ascertained in and by the following statement:-
Our improvements have for their object the simplification and cheapening of
the manufacture of arc lamps and are equally applicable to continuous current
open are lamps, alternate current open arc lamps, continuous current enclosed
are lamps, and alternate current enclosed arc lamps, and to any of the above
classes of arc lamps, no matter whether the regulation is effected by the shunt
winding or by a series winding or by both a shunt and series winding.
The essential features of our new are lamps are the following, shown in
Figures 1, 2, 3 and 4, and consist of a base plate a having one or more flanges
and four vertical tubes attached to it, the position of these tubes when seen in
plan view is preferably 90 degrees apart, two of them passing right through the
base plate, the other two do not. These tubes accordingly form a guide or a
support for the lower portion of the lamp as well as four pedestals above the
base plate, which serve to support the mechanism.
Through the base plate there also passes approximately in a central position
a vertical metal tube c which contains the carbon d with its holder and spring
contact similar to that described in the Specification of Letters Patent No. 6276
dated March 10th 1897 granted to R. E. B. Crompton and E. A. N. Pochin.
At the bottom of this tube we prefer to attach the clutch or feeding device y
and at the top of it we secure the piston or plunger e of the dash pot f, herein-
after mentioned. The four tubes are braced together at their upper ends by a
suitable casting g, which also serves to support the dash pot, and a prolongation
of them may also be used to support a choking coil, transformer, resistance or
any other equivalent device which may be found necessary in practice to control
and regulate the lamp. These tubes also serve to hold the outside cover of the
lamp. The pair of tubes which extend downwards from the base support at their
lower ends an insulated cross piece h which carries the inner or arc enclosing
globe i, preferably by means of a gland or stuffing box j, provided with packing
of a suitable material such as is commonly used where a tight joint is required
and where the temperature is somewhat high. To the cross piece h is fixed the
lower carbon holder.

page_text: The inner globe is fitted with an air excluding cap k through which the upper
carbon passes. This cap also serves as a fixed point on which a suitable clutch
ycan strike to permit the carbon to feed downwards. In Figures 1 and 3 a clutch
of the tilted washer type is shown.
For controlling the feed of the carbon we employ two vertical solenoids I, m
fixed to the above mentioned vertical tubes or rods with their axes parallel to
one another and vertical. These two solenoids contain iron cores n, o capable
of motion up and down vertically within them. The lower ends of these iron
cores are connected one with another through suitable links p to a horizontal
rocking lever pivotted on a horizontal axis at or near the centre and on the
base plate above mentioned and in such a manner that when one iron core moves
up (being drawn into its solenoid) the other core is pulled down.
To the central tube containing the carbon holder and carbon is attached
rigidly an arm projecting from it at a right angle and engaging with one of
the above mentioned iron cores in such a manner that as this iron core rises or
falls the central tube is raised or lowered with it and to the same extent,
In the case of a differentially wound arc lamp in which the regulation is
effected both by a series and a shunt winding, one of the solenoids is wound with
a series winding, the other with a shunt winding. The arm projecting from the
central tube engages with the iron core of the series wound solenoid, and the
solenoid windings are proportioned so that when the lamp is switched on this iron
core is drawn up into its solenoid in spite of the counter pull of the shunt wound
solenoid on its core, and by so doing it raises the central tube with the carbon
and so strikes the arc.
The regulation of the lamp will now be carried on both by the shunt and series
winding in the well known manner common to all differentially wound arc lamps.
In the case of a series or shunt wound arc lamp we either dispense with the
winding on one of the solenoids and substitute for the iron core of that solenoid
a balance weight, or we wind both solenoids with a shunt or series winding as
the case may be and arrange the iron cores so that one solenoid draws its iron
core upwards and the other solenoid draws its iron core downwards with the
result that both solenoids assist one another in moving the above mentioned
rocking lever one way or the other and therefore in raising or lowering the central
tube containing the carbon.
The arm projecting from the central tube must be attached to whichever iron
core moves upwards when the current is switched on to the lamp. In a modified
form of this improved are lamp we arrange the rocking lever immediately above
the solenoid instead of below, pivotting it on any convenient support attached to
the upper part of the lamp.
The various modifications of solenoid windings and iron cores and the use of
counterweights as above mentioned are equally applicable to this modification.
It is usual in lamps of this class to attach a dash pot. In our improved lamp we
prefer to make this dash pot an air dash pot, and one method of arranging it
shown in Figures 1 and 3, is to fix the cylinder of the dash pot f to the upper
part of the lamp centrally over the central tube as mentioned above, and at such
a height that the piston of the dash pot e which is attached to the top of the
central tube can move vertically up and down within the cylinder as the central
tube moves up and down. We sometimes prefer to fix the cylinder of the dash
pot coaxially with one or other of the solenoids and immediately above or below
it, attaching the piston of the dash pot to the iron core of the solenoid in question.
Another alternative is to attach the cylinder of the dash pot to the base or to
the upper part of the lamp with its axis parallel with the central tube and to
attach the piston of the dash pot to a short vertical rod attached to an arm pro-
jecting from the central tube or other moving part, so that as the central tube
moves up and down the piston also moves up and down within the dash pot
cylinder.
In this case also the positions of the dash pot cylinder and piston may be

page_text: reversed if desired, the piston being fixed to the base of the lamp and the cylinder
to the central tube or other moving part, and moving up and down with it.
Instead of permitting the clutch to act by resting on the air excluding cap of
the inner globe we sometimes prefer to provide a separate and independent fixed
point for the clutch to rest on.
Having now particularly described and ascertained the nature of our said in-
vention, and in what manner the same is to be performed, we declare that what
we claim is:-
-
1. In are lamps of the kind hereinabove described, the use of two vertical
solenoids containing iron cores, capable of vertical up and down motion within
these solenoids, the said iron cores having two of their ends attached to a hori-
zontal rocking lever, together with an arm attached rigidly to and projecting
from the central carbon containing tube and connected to one or other of the
iron cores, so that as this iron core moves up and down vertically the central tube
moves also and to the same extent, substantially as hereinabove described.
2. In arc lamps of the kind hereinabove mentioned the use of a single solenoid
containing an iron core capable of vertical up and down motion within this
solenoid, the said iron core having one end attached to a horizontal rocking lever,
the other end of this rocking lever having attached to it a balance weight, to-
gether with an arm attached rigidly to and projecting from the central carbon
containing tube and connected either to the iron core of the solenoid, or to the
balance weight, according to whether the lamp is intended to be worked with a
series coil only or with a shunt coil only, so that the central carbon containing
tube is moved up and down vertically to the same extent as the iron core or the
balance weight, substantially as hereinabove described.
3. In arc lamps the arrangement and combination of parts substantially as
herein described and set forth in the drawings attached hereto.
Dated the 1st day of Var 1000
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.