Improvements in Electric Arc Lamps.
Year: 1898

page_text: Date of Application, 10th June, 1898-Accepted, 17th Sept., 1898
Improvements in Electric Arc Lamps.
We, THE BRITISH 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
The present invention has for its object to improve the construction of the
clutches employed on electric arc lamps, and particularly those in which the clutch
works directly on the carbon pencil
-
In the case of enclosed are lamps, the arc is usually at first at the top of the
inner globe, and during the operation of the lamp becomes gradually lower in
position till the bottom of the inner globe 18 reached This leaves a certain length
of upper carbon-1od which, when the lamp is trimmed, 18 used as a lower carbon
Economy in the use of carbon is obtained when this remnant which is to be used
as a lower carbon is of the proper length, that is, neither too long nor too short.
If the clutch is too far away from the top of the cap of the inner globe, the remain-
ing piece of the upper carbon is apt to be too long; it is therefore best to have
the clutch operate very close to the cap of the inner globe which forms the "floor "
of the clutch
In arc lamps having clutches working directly on the carbon pencil, it is neces
sary to provide a weighted follower so that the carbon pencil will feed after its
weight has been reduced by burning In retrimming a lamp of this character,
it is more or less difficult to hold the weighted follower while the carbon pencil
18 being inserted into place, due to the lamp mechanism. Heretofore it has been
customary to insert the carbon in place and force it upward until the weighted
follower struck a stop in the upper part of the lamp, after which the carbon pencil
could be forced into the clamping jaws of the weight This was an objectionable
arrangement, principally because the spring clamping jaws of the weight could
not be seen, and they were hable to be bent while the carbon was being inserted
To overcome this objection, the clutch is made in such a manner that it can be
forced upward to a point where it will open sufficiently to permit the weighted
follower to be removed. the carbon pencil may then be mounted in place, and
the weighted follower returned to its position in the lamp,
In addition to securing these advantages there is provided a clutch which 18
simple, positive and reliable
In the accompanying drawing, which shows the invention applied to an arc
lamp, Fig 1 is a front elevation of the improved clutch with certain portions
broken away; Fig 2 is a perspective view of one element of the clutch, Fig. 3
is a detail view showing the position of the clamping surfaces with respect to the
carbon, Fig 4 is an inverted plan view of the clutch; Fig. 5 18 a rear elevation of
the clutch and carbon pencil; and Fig. 6 is a front elevation of an enclosed aro
lamp, with a part of the casing broken away.

page_text: Surrounding the carbon pencil C 18 a tube R¹ which is connected to the armature
of the operating magnet M1 in any desirable manner. Secured to the lower end of
the tube is a clutch which works directly on the carbon pencil C. The clutch 18
provided with a split collai A, which is secured to the tube R¹ by the screw A¹
Projecting downward from the collar are two lugs A² forming supports for the
jaws B, B of the clutch The clutch jawa are counterparts, so that a single
pattern may be employed for both, this simplifies the construction of the clutch,
and at the same time obviates trouble when parts are ordered by the users, as
the question of night or left hand does not have to be considered The extension B¹
of the clutch Jaw 18 slotted to receive the link D which forms the connection
Letween it and the split collar Å The links I are made of thin pieces of metal, of
uniform thickness, and are preferably punched from sheet metal, on account of
cheapness. The slots in the lugs A and B are somewhat wider than the thick-
ness of the links, so as to permit the latter to work freely and to adjust them-
selves for regularities in the carbon.
Two arms B and B are provided on each clutch jaw, the arm B³ being long
and terminating in a curved end which is employed to trip the clutch, and the
aim B being short and extending only to the center of the carbon The arms B³
are curved towards each other, so that their ends, which rest on the floor of the
clutch, are substantially in the same straight line; this arrangement ensures the
proper tripping action of the clutch.
By varying the length of the arm B³, the clutch can be made more or less sensi-
tive, as the length of the arm increases, the sensitiveness of the clutch increases
Two angular clamping faces B5, B6 are provided on each jaw, these are so arranged
that when the clutch is assembled, the jaws will automatically adjust themselves
with respect to the pencil and the four faces of the clutch will grip the carbon
pencil
The successful action of the clutch 18 largely dependent upon the position which
the pivots E between the jaws occupy with respect to the clutch faces B5 and Be
It has been found by experiment that the action is more successful when the
pivots E are comparatively low, to obtain this effect, the pivots are mounted in
the downwardly-extending lugs B² In certain instances, however, where a deli-
cate adjustment is required, the pivots E are made more nearly in line with the
angular gripping faces B5 and B The two jaws of the clutch are pivotally
united at the point of crossing by the screws E, which are threaded at the end
where they enter the jaws, the remainder of the screw being left plain. By this
arrangement the uncut portion of the screw acts as a shoulder, and also as a jam
nut to hold the screws from becoming loose and dropping out. Referring to Fig 1,
it will be seen that considerable lateral play is permitted between the jaws at
the pivots E; this is to provide for lateral adjustment of the clutch, when the
carbon pencil C 18 slightly out of line, or is irregular in shape.
Fig 3 shows the manner in which the jaws grip the carbon pencil C. It will
be seen that the upper edges of the angular faces are in engagement with the car bon.
The clutch as constructed requires no finishing, with the exception of the split
collar A and the angular clamping faces Be and B', and even in these parts the
amount required 18 very small.
In order to insure a positive feed for an are lamp in which the clutch works
directly on the carbon pencil, it is necessary to provide a weighted follower 80
arranged that it will assist the carbon to feed, this is a particularly important
when the greater part of the carbon has been consumed In the present instance
there is shown a weighted follower composed of a main body of metal G, with
phosphor bronze springs G¹ arranged to make contact with the inside of tube R¹
and supply current to the upper carbon C, but the design of the follower may be
widely varied without departing from the spirit of the invention. On the lower
end of the weighted follower is a carbon holder consisting of a split metal tube H,
arranged to grip the carbon To facilitate the trimming of the lamp, the weighted
follower is so arranged that it can be removed from the lamp by pushing the jaws

page_text: of the clutch upward to the position shown in Fig. 1. This is a highly desirable
arrangement, as it also permits the trimmer to save considerable time, and it also
prevents injury to the lamp parts which was formerly occasioned in lamps not
having a removable follower, by ramming the carbon pencil C upward until it
was caught and gripped by the holder H.
In Fig. 6 is shown a front elevation of an arc lamp provided with an arc-enclos-
ing globe 1 having a metal cap I' which 18 arranged to act as the floor of the
carbon clutch The enclosing globe is secured in place by a globe-holder J which
18 mounted on a support K carried by the side rods L. Mounted in the mechanism
chamber of the lamp is the actuating magnet M, and depending from the chamber
18 a frame composed of the side rods L and support K
There is always a certain amount of carbon left in the upper carbon holder after
the lamp is cut out, and by properly proportioning the lamp parts the remaining
When a
piece may be employed for the lower carbon when the lamp is trimmed
portion of the lamp frame is employed as the floor of the clutch, the piece remain-
ing in the holder is too short, unless the lamp frame 18 made unduly long, but
by employing the cap of the inner globe as the floor of the clutch, the frame may
be made short, a most important feature in commercial arc lamps, and by
adjusting the vertical height of the cap, the carbon remaining after the lamp is
cut out, may be made of any desned length.
The action of the lamp is as follows. as the actuating magnet weakens, it
permits the tube R to drop, and the outer ends of the clutch arms B³, striking the
top of the cap I¹, will release the carbon and permit it to feed by gravity In the
upward movement of the tube, the jaws are drawn together and firmly clutch the
carbon, the clutch operating like a toggle actuated by the weight of the carbon,
aided by that of the weighted follower found in lamps of this type.
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 18:-
1 In a carbon clutch for arc lamps, the combination of a collar secured to the
tube surrounding the carbon, downwardly-extending projections situated on each
side of the clamp, links pivoted to the lower ends of the projections, Jaws which
are pivotally secured together and to the links, and angular clamping faces which
engage directly with the carbon.
2 In an arc lamp, the combination of a tube surrounding the carbon, a detach-
able collar secured thereto and provided with downwardly-extending projections,
a clutch consisting of counterpart jaws adapted to grip the carbon, and links
between the jaws and the clamp projections.
3 In a clutch for aic lamps, the combination of a clamp consisting of two
counterpart elements, counterpart jaws each provided with angular gripping faces,
and counterpart links connecting the clamp with the jaws.
4 In a carbon clutch for are lamps, the combination of a split collar having
extensions thereon to receive the clamping screw, downwardly-extending lugs
thereon, counterpart jaws forked at one end, the arms of the fork extending
on each side of the carbon, angular faces on each jaw for gripping the carbon,
and a link between each jaw and the downwardly-extending clamping lugs.
5 In a clutch for an arc lamp, the combination of a collar which 18 secured
to the actuating mechanism of the lamp, and a pair of counterpart clamping jaws
loosely suspended from the collar, each jaw being provided with a long and a
short arm, the long arm acting to trip the clutch
6 In a clutch for an arc lamp, the combination of a collar which is secured to
the actuating mechanism of the lamp, a pair of counterpart clamping jaws loosely
suspended from the collai, each law provided with a long and a short aim, the
long arm acting to tip the clutch, and pivots between the long arm of one jaw
and the short arm of the other jaw.
7. In a clutch for an arc lamp, the combination of a collar which is secured

page_text: to the actuating mechanism of the lamp, a pair of counterpart clamping jaws
suspended from the collar, two angular faces on each jaw for gripping the carbon,
the faces on one jaw being adjustable laterally so that they will automatically
adjust themselves to irregularities in the carbon, and means for tripping the clutch
8. In a clutch for an electric arc lamp, the combination of a support secured to
the actuating mechanism of the lamp, a pair of clamping jaws suspended from
the support, and extensions on the jaws for tripping the clutch, which are curved
on their outer ends to a point where they are substantially in line with the carbon
pencil.
9 In an arc lamp, the combination of a weighted follower which rests on the
top of the carbon pencil, and a clutch which normally grips the carbon, but feeds
it downward as it is consumed, the clutch being so arranged that it can be opened
to permit the removal of the weighted follower.
10. In an arc lamp, the combination of a weighted follower to which the upper
carbon is secured, a contact between the follower and a stationary part of the lamp,
and a clutch which normally gips the carbon, but releases it when the lamp
magnet becomes weak, the arrangement of the clutch and the weighted follower
being such that under normal conditions the follower is prevented from passing
through the clutch, but as soon as the clutch is manually lifted, the follower
may be removed from the lamp for the purpose of retrimming.
11. In an electic arc lamp, the combination of an arc-enclosing globe, a support
for the globe, a clutch for gripping the carbon, and a cap for the enclosing globe,
which acts as the floor of the clutch.
12 In an electic are lamp, the combination of a chamber for the mechanism,
a clutch which works directly on the carbon pencil, a frame depending from the
frame of the lamp chamber, an arc-enclosing globe supported by the frame, and a
floor for the clutch, also supported by the depending frame.
Dated 1... 04h la of T 1900
THE BRITISH THOMSON-HOUSTON CO., LTD.
A. R MONKS,
Director.
ALFRED CLEMENTS,
Assistant Secretary.