Improvements in Arc-lamps.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Arc-lamps.
I, FREDERICK BOOKER, of 19, Swallowfield Road, Charlton, in the County of
Kent, Electrical Engineer, do hereby declare the nature of this invention to be
as follows:-
This invention relates to electric arc-lamps of that type in which the position
of the carbons is regulated through the action of solenoids, and the object of the
invention is to provide a brake in connection with the solenoids which shall be
exceedingly sensitive in its action, and whereby the adjustment of the carbons
in the lamp is effected with greater precision than has been possible heretofore.
For the purposes of my invention I provide on the brake spindle carrying the
ordinary drums for regulating the carbons, a fixed disc, or cup-shaped receiver
of any appropriate material or metal against .which acts another but loosely
arranged disc, also preferably of metal, on the same spindle. The two brake
discs are normally kept at a slight distance, apart by means of a coiled spring
placed on the spindle between them. The cup-shaped disc is provided internally
with a ring of rubber or other suitable material for the purpose of taking up
the friction produced by the loose disc.
If an ordinary fixed disc be employed instead of the cup, such disc may advanta-
geously have a circular groove cut in its face to receive and hold the rubber or
friction-ring. The loose disc is provided on its outer face with inclines located
diametrically opposite each other, which may be in the form of a portion of
the path of a double-threaded screw and the disc is further provided with a
pivotted link, connected by one end to the rocking lever of the solenoids in
such a manner as to impart a slight rotary motion to the said loose disc at
every movement of the rocking lever. The inclines on the loose disc during its
rotary motion are brought into the path of anti-friction rollers carried on a
cross-arm or plate connected to the bearing of the brake-spindle, and by this
means the loose disc is gradually pressed toward the cup or fixed disc and against
the friction ring, which thereupon are both caused to move together. This
arrangement forms a very sensitive and reliable brake for regulating the motion
of the drums. In some cases however I may form the inclines upon the fixed
arm carrying the bearing of the brake-spindle and then mount the friction
rollers in brackets or checks secured to the loose disc.
It will be obvious that the combined rotary and sliding motions of the loose
disc produce the effect of a screwing motion which on being transmitted to the
friction ring of the fixed disc effectually prevents any jerky movements of the
fixed disc and consequently of the drumis regulating the position of the carbons.
I advantageously so construct the cross-arm or plate carrying the antifriction
rollers so as to be capable of making a slight rocking motion, and so enable it
to adapt itself automatically to any slight unevenness, brought about by wear or
the like, in the two inclines, and I also find it advantageous to so support the

page_text: brake-spindle in its bearings as to allow it to move endwise therein a sufficient
distance to prevent a strain being exerted by the action of the brake on the
arms carrying the bearings of the said spindle.
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1000
Improvements in Arc-lamps.
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1. FREDERICK BOOKER, of 19, Swallowfield Road, Charlton, in the County of
Kent, 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:-
-
This invention relates to electric arc-lamps of that.type.in which the position
of the carbons is. regulated, through the, action of solenoids, and, the object of
the invention is to provide a brake operated by the solenoids which shall be
exceedingly sensitive in its action, and whereby the adjustment of the carbons
in the lamp is automatically effected with greater precision that has been the
case heretofore.....
According to my invention I fix on the brake-axle which carries the carbon
suspension-drums a device in the nature of a friction-clutch and consisting of
a fixed disc or cup-shaped receiver, made preferably of metal, against which,
acts another but loosely arranged disc, also preferably of metal, and on the same
axle. These two brake discs are normally kept at a suitable distance apart
by .means of a coiled spring interposed on the same axle. The fixed disc is
provided on its face next to the loose disc with a ring of rubber or other suit-
able material for the purpose of taking up the friction produced by the compound
movement of the loose disc hereinafter explained.
If an ordinary flat disc be employed instead of the cup or flanged disc, such
flat disc may advantageously have a circular groove cut around its face to receive
and hold the said rubber or friction-ring. The loose disc is provided on its
outer face with a pair of inclined planes located diametrically opposite to each
other and in the form of a portion of the pitch of a double-threaded screw;
to the disc is attached one end of a link, connected at the other end to the
ordinary rocking-lever actuated by the solenoids in such a manner as to impart
to the said loose disc a slight rotary motion corresponding to each movement
of the rocking-lever. The inclined planes on the loose disc during its rotary
motion are gradually brought into the path of anti-friction rollers carried on
a cross-armed plate connected to the bearing of the brake-axle, and by this
means the loose disc is gradually pressed and advanced towards the cup or fixed
disc, and against the friction-ring thereof; so that both discs are then caused to
rotate together. This arrangement forms a very sensitive and reliable brake for
regulating the motion of the carbon suspension-drums.
I will now describe my invention in detail, referring in so doing to the accom-
panying drawings, in which Fig. 1 is a front elevation and Fig. 2 a side eleva-
tion with the left hand solenoid removed; showing the working mechanism of
an arc-lamp provided with my improvements. Figs. 3 to 10 illustrate details
of my invention hereinafter explained. A is the shunt-wound and B the series-
wound solenoid, both mounted on. the supporting plate C, and a and b are
their respective cores pivotted to the rocking-lever D which is fulcrummed at d
"

page_text: between the arms c of the fixed bearing or bridge-plate E. So far this arrange-
ment' is well-known and forms no part of my invention.
The bearing plate or bridge E is provided with lugs e¹ e carrying vertically
depending arms and respectively, having bearings for the brake-axle. F.
This brake-axle F carries the two rotary carbon suspension brake-drums .G G!,
to which are fixed suspension cables or chains 0, P leading respectively to the
upper and lower carbon frames of the lamp, for adjusting the position of the
carbons during the working of the lamp. To the drums G G¹ on the axle F
according to my invention I firmly secure the disc H which may be flat or
flanged; one form is shown separately in Figs. 3 and 4 in front view and in
horizontal section; around the inner circle of this disc is placed the rubber ring
I of any appropriate section, preferably square. Adapted to pass within the
flange h of the disc H (if used) is mounted loose on the axle F à second disc. K,
Figs. 5 and 6, of brass, or other suitable material, so as to be capable of being
rotated and at the same time slidden Endwise on the spindle F for the purpose
of being advanced and pressed against the rubber ring I, or of being moved away
therefrom; the two parts H and K and the rubber ring I, thus form a species
of friction-clutch; a spring N with regulating screw n is provided for the pur-
pose of taking up the endwise and screwing movement of the axle F when the
brake is applied, and returning all parts to normal position on its release.
Normally the loose disc K is kept away from the rubber ring I by the pres-
sure of a small interposed coiled spring (not shown) but surrounding the
spindle F. The disc K is connected by a stud k to a link L pivotted at / to the
rocking-lever D, and is thus normally kept stationary until the said rocking-
lever is moved by the action of the solenoids. On the outer face of the disc K
are formed a pair of inclined planes 2 k³ arranged diametrically opposite to
each other and with their inclined surfaces disposed in reverse directions, though
in the same path, and in such a manner as to simultaneously impinge against
an abutment located in front of the disc K. The said abutment consists of
a cross-armed plate M, shown clearly in Figs. 8, 9 and 10, secured to a boss e
on the supporting arm e³. The swivelling connection between the part. M and
the supporting arm e is illustrated in Fig. 7 while Figs. 8, 9 and 10 are
respectively a front elevation, a' plan, and an end view of the cross-armed plate.
I generally secure the plate M to the boss by means of pointed set-screws m
passing through tapped holes in the central ring-shaped portion m¹ of the
plate M. as shown, so that, when properly adjusted, the screw points enter
indentations provided in the boss for their reception. The ring-shaped cen-
tral portion m' is of somewhat larger diameter than the boss e and the plate M
is thus capable of a slight lateral motion in order to adjust itself automatically,
or to yield to any small irregularity in the inclined planes caused by wear
or otherwise.
With a view of preventing undue friction between the plate M and the inclined
planes on the disc K I provide antifriction rollers m² m³ mounted on pins as
shown and disposed near the ends of the cross-armed plate in juxta-position to
the inclines³, so that on the disc K being rotated these inclines are moved
into the path of and beneath the said rollers m² m³, which then advance the moving
disc K inwardly, and compress its spring.
It is advantageous to form serrations such as on the inner bearing surface
of the loose disc K, and thus increase its gripping power on the rubber ring I.
It will be obvious that the compound rotary and sliding motion of the loose
disc K produces the effect of a gentle screwing action exerted against the rubber
ring I, which action, when sufficiently continued, causes the fixed disc H to
participate in the rotary motion of the disc K.
"I may of course reverse the above described arrangement by forming the
inclines on the cross-armed plate' M and mounting the antifriction rollers.in
brackets or cheeks on the loose disc K, without departing from the nature of
my invention.

page_text: The action of my improved brake is as follows: The lamp being inert and
the carbons in contact when the current is switched on it passes through the
series-solenoid B (which is in the main circuit of the lamp) and draws its core b
inwards as is indicated by the arrow 1 thereby moving the rocking-lever: D and
raising the link L. This latter thereby imparts a slight rotary motion to the
loose disc K causing the inclined planes to pass under and to impinge
upon the antifriction rollers m² m³. At first this motion may be without effect
but when sufficiently increased it forces the disc K inwardly against the rubber
ring I compressing at the same time the internal spring interposed between the
lises. By the friction thus engendered the fixed disc H and consequently also
the brake-drums G G fixed thereto are rotated more or less in the direction
indicated by the arrow 2, and thereby cause the connections O and P to separate
the carbons and strike the arc, the one, 0, raising the carbon-carrier Q and the
other, P, lowering the carbon-carrier R in the ordinary manner.
push of the axle F is counteracted by the spring N which is capable of adjust-
ment by the screw n to suit varying conditions of current strength.
The endwise
When the are becomes too long, owing to consumption of the carbons, the
attractive power of the shunt-coil A predominates over that of the series-coil B
and draws the core a inward, as indicated by the arrow 3, in opposition to the
series-coil, thereby retiring the inclined planes
from under the rol-
lers m² m³ when the internal compressed spring forces back the disc K and
reduces the pressure on the rubber ring I until it is insufficient to sustain the
normal weight of the carbon-carriers; thus the brake is released and allows the
drums G G to be rotated in an opposite direction to the arrow 2 by the pull
of the heavier carbon-carrier Q, so drawing the carbons together and reestab-
lishing the proper length of the arc. When the strength of the shunt-solenoid
becomes reduced below that of the series-solenoid, further movement of the
carbons is retarded.
The screwing motion of the improved brake arrangement both in applying
and in releasing the brake is so gradual and sensitive that any abrupt move-
ments are prevented and a regular and even feed is ensured.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what
I claim is;-
1. As a friction, brake for electric arc-lamps of the kind above referred to,
the arrangement upon the axle of the carbon suspension-drums of a fixed and
a loose disc, the latter having imparted to it by the actions of the solenoids and
gear described, a compound advancing and screwing motion, whereby the pres-
sure applied by the loose part to the fixed part and drums is varied propor-
tionally with the action of the solenoids, in such manner as to control the
carbon feed in the manner above set forth.
2. A brake for electric are-lamps in the nature of a friction-clutch compris-
ing the two coacting parts H and K constructed and arranged as above specified,
whereby each movement produced by the solenoids is converted into a rotary
motion of one part K of the brake and gradually imparted to the other part H
and to the carbon suspension-drums G G¹, and by them through suitable con-
nections to the carbon-carriers, all arranged and adapted to operate substantially
as and for the purposes herein described.
3. A friction brake for arc-lamps, consisting of a disc such as H rigidly con-
nected to the rotary carbon suspension-drums and their axle F, and provided
with a friction-ring I, in combination with a corresponding spring-pressed disc K
loosely mounted on the same axle F, and having a link connection with the
rocking-lever of the solenoids, and furnished with inclines adapted to co-operate
with antifriction rollers carried by an adjustable plate M, the whole being
arranged or adapted to operate at- the times and substantially in the manner
described and illustrated in the annexed drawings.

page_text: 4. The arrangement in combination with the friction brake for arc-lamps
referred to in the foregoing claims of the adjustable spring N as and for the
several purposes described.
5. The improved arrangement of friction brake for electric arc-lamps herein
described and illustrated by the drawings.
Dated this Twenty-sixth day of January 1899.
J. C. CHAPMAN,
Chartered Patent Agent, 70, Chancery Lane, London, W.C.