Improvements in Electric Arc Lamps.
Year: 1898

page_text: Date of Application, 27th Oct., 1898-Accepted, 10th Dec., 1898
COMPLETE SPECIFICATION,
Improvements in Electric Arc Lamps.
We, THE BRITISHI THOMSON-HOUSTON COMPANY LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of this
invention (which has been communicated to us from abroad by Henry C. Spinney,
residing at Lynn, in the County of Essex, State of Massachusetts, United States
of America, Electrical Engineer) and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement:-
In electric arc lamps having a small cylinder or globe surrounding the arc, with
clutches working directly on the carbon, it has been customary to utilize the cap of
the cylinder as a floor for tripping the clutch. This arrangement presents
several advantages among others that it permits the lamp to be shortened, is more
economical in the use of carbon, and renders the parts more accessible to the
trimmer. Within certain limits this arrangement is satisfactory, but where
cylinders of different makes or varying heights are used, the tripping point of the
clutch is varied, and therefore it is unnecessary to adjust the lamp to a greater
or less degree. To overcome the objections, and at the same time retain the
advantages above pointed out, the floor of the clutch is mounted in such a manner
that it is situated at or about the height of the cylinder cap, but separate there-
from.
With arc lamps having detachable caps for arc-enclosing cylinders, it often
happens that the trimmer will drop the cap as he is trimming the lamp. This
is a particularly objectionable feature, for practically each time a cap is dropped
it means that a new outer globe must be supplied to the lamp. It is also objection-
able even in lamps without outer globes, as it necessitates the trimmer descending
from his ladder to pick up the cap. These caps, due to their proximity to the arc,
get very hot, so that they cannot be handled without the use of pliers or some
similar device, and it is while handling them in this manner that they most fre-
quently drop and break the outer globe.
On account of the variations in the cylinders, it is desirable that these caps shall
be so supported that they are free to adjust themselves in a vertical and horizontal
direction. This, is accomplished by permitting the caps to rest on the top of the
cylinder. To prevent the cap from dropping and at the same time permitting it
to adjust itself, a support is provided which is so arranged that the cap is permitted
to move freely up and down within certain limits, and also laterally for the purpose
of adjustment, but is prevented from dropping to a point where it will endanger
the globe.
This invention has for its object to improve the construction of enclosed are
lamps, and to that end consists in the parts and combination of parts as herein
described and claimed.
In the accompanying drawing, which shows an embodiment of the invention,
Fig. 1 is a partial front elevation of a lamp with the outer globe in section;
Figs. 2 and 3 are respectively a side elevation and plan of the cap support and floor
for the clutch, and Fig. 4 is a perspective view of a slight modification.
Secured in any desirable manner to a fixed portion of the lamp, is a flat, sub-

page_text: At
stantially circular support or cage A; in the present instance the support is carried
by two vertically-extending posts B and B¹, which are secured to the under side
of the lamp base C. The centre of the support is provided with an opening K
through which the upper carbon moves in a free and unobstructed manner.
the lower end of each post is a long screw B2, and by substituting screws of different
length, the position of the support or cage A may be adjusted as desired, either for
the purpose of regulating the tripping of the clutch or for changing the position of
the cap.
This is a desirable feature where adjustments of a radical nature are
desired, but for simple adjustments, the freedom of movement permitted to the
cap D, to be hereinafter described, is sufficient to compensate for changes in the
heights and other irregularities of the different cylinders.
The support is shown rigidly secured in place by two upwardly extending lugs A¹,
through which extend the screws B2, but this construction may be varied as desired.
The cylinder cap D is loosely suspended from the under side of the support or
cage A by means of the hooked lugs A2 and the screw A³, the latter being mounted
in an extension A' of the support. The lugs and screw are so arranged that they
support the cap at three points, which points are angularly displaced at 120°
This has been found to be a convenient arrangement for by taking out the screw A³
the cap may be removed, but any other means for suspending the cap may be
employed. The distance between the under side of the support and hooked end
of the lugs is considerably greater than the thickness of the cap; this is to permit
the cap to have a certain freedom of movement in a vertical direction to compensate
for the varying heights of the cylinder E. By this arrangement cylinders may be
employed which differ materially in their height. A space is left between the
cap and its supports to permit the former to have more or less lateral adjustment,
to compensate for irregular cylinders.
The cap when supported in the manner shown has great freedom of movement,
and will readily adjust itself with respect to the cylinder, and so long as the cylinder
is anywhere near the proper size and shape will work in a satisfactory manner.
One decided advantage of the construction shown lies in the fact that the cap
does not have to be made special in any particular, and also that the cage A may
be applied to the lamps already in use.
The cylinder E surround the carbons G and G¹, and is secured at its lower end
to the lamp frame H by a suitable clamp or holder F. Normally the cap D rests
on the top of the cylinder, and is supported thereby, the support or cage A only
coming into play when the cylinder is removed.
Surrounding the upper carbon G is a tube I, and carried by the end of the tube
is a clutch J of any suitable construction. The one shown is arranged to work
directly on the carbon and consists of a pair of pivoted jaws J¹ and J, which are
united by links J³ with a collar I¹ carried by the tube I. The extensions on the
jaws J¹ and J2 are arranged to strike the top of the support A, which constitutes
the floor of the clutch; as shown the clutch is in its extreme lower position, and
the carbon is released. By situating the floor of the clutch at a
fixed distance from the base of the lamp, the clutch J will trip at a certain
point each time the tube I, which is connected to the lamp actuating mechanism,
drops a certain amount; whereas with the cap itself arranged to act as the floor of
the clutch, the action is not so definite.
.:
In Fig. 4 is illustrated a slight modification of the invention, in which a special
cylinder cap is employed, having lugs a formed integral therewith. These lugs
are provided with holes for the reception of the supporting screws B2, the relation
between the parts being such that the cap is free to adjust itself in a vertical direc-
tion and also to tilt slightly to compensate for irregular cylinders. Supported by
shoulders formed on the screws B2, is a flat plate A having a central opening K for
the carbon, which acts as the floor of the clutch. This plate is preferably fixed
with respect to the bottom of the lamp, but if desired it may be capable of move-
ment toward the lamp base; the chief requisite being that it shall have a definite
seat so that adjusting of the carbon clutch is unnecessary.

page_text: The cap for the cylinder comprises two parallel plates or flanges which are con-
nected by a central hub, the upper flange being provided with lugs for the recep-
tion of the screws B2, while the lower flange is arranged to fit inside of the cylinder
and assist in forming an air chamber.
It will be seen that the holes in the plate A are larger than the screws 132; this
permits the plate to rock slightly on a horizontal axis for the purpose of adjustment,
and also permits one side of the plate to move slightly in a vertical direction. This
arrangement constitutes in effect a support having a universal movement.
It is well understood that this is not the first instance where a carbon clutch is
made, which is located at a fixed point with respect to the lamp, but in all of the
lamps familiar to those skilled in the art, the clutch floors are located at or near
the base of the lamp, or else the cylinder cap is utilized to act as the floor of the
clutch. For certain purposes the former arrangement may be employed, but it
is not so economical in the use of carbon, as the piece remaining in the lamp is
not long enough, to use as an upper carbon, and it is too long to use as a lower
carbon. With the clutch having a fixed floor and working at a point below the
base and near the cylinder cap, it is enabled to materially shorten the lamp, to
economize in the use of carbon, and to utilize the remaining piece of the upper
carbon when retrimming, as the lower carbon, and this without changing its length.
It is believed to be broadly new in connection with an enclosed arc lamp, to
suspend the cylinder cap in such a manner that while it is free to adjust itself
with respect to the cylinder to compensate for irregularities therein, it is prevented
from dropping from the lamp when for any reason the cylinder is removed.
Having now particularly described and ascertained the nature of our said inven-
tion (as communicated to us from abroad) and in what manner the same is to be
performed, we declare that what we claim is :-
1 In an electric arc lamp, the combination of a globe or cylinder which encloses
the carbons, a cap which rests on the top of the cylinder and prevents the free
entrance of air into the cylinder, and means for retaining the cap within the lamp
when the cylinder is removed.
2-In an electric arc lamp, the combination of a globe or cylinder which encloses
the carbons, a cap which is arranged to close one end of the cylinder and is free
to adjust itself with respect to the cylinder, and means for retaining the cap in
place after the cylinder is removed.
3-In an electric arc lamp, the combination of a globe or cylinder which encloses
the carbons, a cap which rests on the top of the cylinder and prevents the free
entrance of air into the cylinder, and a cage or support for the cap which is normally
out of use, but which retains the cap at or near its normal position when the
cylinder is removed.
4-In an electric arc lamp, the combination of a globe or cylinder which encloses
the carbons, a cylinder which surrounds the carbons, a cap supported by the
cylinder during the normal operation of the lamp, a cage or support normally idle,
in which the cap is loosely mounted, but so arranged that it will prevent the cap
from falling when the cylinder is removed, and means for suspending the cage or
support from a fixed part of the lamp.
5 In an electric arc lamp, the combination of a cylinder which surrounds the
carbons, a cap which rests on the top of the cylinder, a cage surrounding the cap
and preventing it from falling, the said cage being provided with downwardly
extending lugs which support the cap at more than one point.
6-In an electric are lamp, the combination of a cylinder which encloses the
arc, a cap arranged to rest on the cylinder and be supported thereby under normal
conditions, a cage for retaining the cap within the lamp when the cylinder has been
removed, the said cage being provided on its under side with means for supporting
the cap at three points.
As an article of manufacture, a support or cage for a cylinder cap, com-

page_text: prising a metal body having lugs for securing it to the lamp frame, hooked lugs
for gripping the cap, and a detachable support permitting the removal of the cap.
8-In an electric arc lamp, the combination of carbon pencils, a clutch working
on the pencils, a floor for the clutch, and means for suspending the floor of the
clutch below the base of the lamp.
9 In an electric are lamp, the combination of carbon pencils, a cylinder sur-
rounding the pencils, a cap for the cylinder, a clutch arranged to work directly
on one of the pencils, a floor for the clutch, a means for suspending the floor of
the clutch at a fixed distance from the base of the lamp, and between the base and
the cap:
10 In an electric arc lamp, the combination of a cylinder, a cap therefor, a
support for the cap, and downwardly extending lugs on the support, which retain
the cap in place when the cylinder is removed.
11 In an are lamp, the combination of a combined cap support and floor for
a clutch, with means for limiting the downward movement of the support, so
arranged that freedom of adjustment is permitted.
12 In an are lamp, the combination of a combined cap support and floor for
a clutch, means for maintaining it at a fixed distance from the lamp mechanism,
and means for permitting the support to have practically a universal motion for the
purpose of adjustment.
13 In an arc lamp, the combination of a combined cap support and floor for a
clutch, a screw threaded support for holding the cap support in place, an upwardly-
extending lug forming the support through which the screw-threaded support
extends, and means permitting the cap to adjust itself, but preventing it from fall-
ing out of the lamp.
14 As an article of manufacture, a support for a cylinder cap, comprising a
flat metal plate having a pair of upwardly extending supporting lugs, and a pair
of downwardly-extending lugs for retaining the cap.
15 As an article of manufacture, a cylinder cap, comprising two flat cylindrical
flanges connected by a hub, one of the flanges being provided with an extension for
supporting the cap.
1000
THE BRITISH THOMSON-HOUSTON CO. LTD.,
W MARTINDALE,
A. R. MONKS,
Directors.
ALFRED CLEMENTS,
Assistant Secretary.