Year: 1897

page_text: ROBERT DOBSON 14 Sackville Street Salford Lancashire Electrical Engineer do
hereby declare the nature of this invention to be as follows:-
In my improvements, I use the solenoids, series, and shunt, free to act inde-
pendent of each other.
The improvements in the striking, and feeding, mechanism, are substantially as
follows.
The upper carbon, is connected to the lower carbon, by a flexible cord, passing over
two pulleys, at the top of the lamp, the upper carbon being weighted, to bring the
upper and lower carbons, together when released by the action of the clutch. One
of these pulleys is pivotted on a fixed bracket, the other pulley is pivotted on a lever.
This lever is pivotted near its centre, on a fixed bracket, its other end being hinged,
to the iron core of the series solenoid. On the core of the shunt solenoid, is hinged
another lever, pivotted near its centre on a fixed bracket, at the other end of this
lever is attached a weight sufficient to overcome the weight of the core, of the shunt
solenoid, at a point near its centre, and between the pivot on which the lever rocks,
and the shunt core, are pivotted two arms, one on either side hanging downwards,
the lower ends of these arms, are hinged or jointed, to the ends of two pairs of levers,
these levers point inwards towards each other, and crossing at the middle are jointed
there, like the letter X with the ends spread out sideways, the flexible cord passing
between these pairs of levers at their centre, at each side of the centre, and on the top
side of the levers, are fixed two projections, shaped to forin a clutch, for the flexible
cord, so that when the top ends of these levers are lifted, or the bottom ends
lowered, these projections move together, and clutch the flexible cord, under the lower
ends of these levers, is placed a rocking bar or plate, and on which these lower ends
may rest, this bar is pivotted near its centre, the other end being under the core
of the series solenoid.
The action of the lamp is as follows, when no current is passing, the bottom end
of the core of the series solenoid, lies on the rocking bar or plate, and raises the
lower ends of the levers to which the clutches are attached, thereby throwing them
clear of the flexible cord, and allowing the carbons to move together, at the same
time the lever hinged to the top end of the core of the series solenoid, raises the move-
able pulley in line with the fixed pulley, The core of the shunt solenoid being held
up by the action of the counterweight on the opposite end of its lever.
When the current is turned on the core of the series solenoid, is attracted upwards,
releasing the rocking bar or plate, and allowing the lower ends of the clutch
levers to fall causing the clutches to grip the flexible cord, and hold it fast, at the
same time this series core, lifts the lever carrying the moveable pulley, causing it to
drop. This allows the lower carbon to fall away, thereby striking the arc.
As the carbons burn away, the resistance of the arc increases, bringing the shunt
solenoid into action, attracting its core downwards, and with it the lever hinged to its
top end, and the two arms hinged to the top ends of the clutch levers, allowing them
to fall untill the lower ends of the clutch levers, rest on the rocking bar or plate,

page_text: opening the clutches, and releasing the flexible cord, and allowing the carbons to
move toward each other, and restablishes the proper length of arc. The force of
gravity, and the pull exercised by the shunt solenoid, are thus continually balancing
each other, with the result, that a constant length of are is inaintained.
I propose to use as a modification, the arrangement of the shunt solenoid with its
lever, counterweight, and clutch levers, as described above, separately as a shunt
lamp.
I propose to use as a further modification, the lever, counterweight, and clutch
levers, as above described, and used in the shunt lamp, but instead of the shunt
solenoid, I propose to use a solenoid, in series with the circuit in which the lamp is
placed the counterweight to be reduced so that the core falls to the bottom of the
solenoid, when no current is passing. When the current is turned on, the core is
attracted upwards carrying with it its lever and clutch levers, and causing them to
clutch the flexible cord, thus striking the arc, as the carbons burn away the
resistance of the are increases, and the current decreases, and allows the core with its
levers to fall down, thus releasing the clutches, and allowing the carbons to move
together, thus maintaining a constant length of arc.
Dated the Ninth day of March 1807
ROBERT DOBSON 14 Sackville St, Salford Lancashire. 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:-
In my improvements in Electric Arc lamp. I use the solenoids series and shunt
free to act independant of each other, The improvements in the striking and feeding
mechanism are substantially as follows.
Refering to Fig 1 the upper carbon is connected to the lower carbon by a flexible
cord f, passing over two grooved pulleys C and D at the top of the lamp. This
flexible cord may be of braided wire of copper or other inetal, or braided cotton,
hemp, linen, or other textile materials, with or without a core of similar material, or
with a core composed of copper or other metallic wire braided or stranded, The top
carbon is weighted to bring the carbons together, when released by the action of the
clutch, One of these pulleys D is pivotted on a fixed bracket, the other pulley C is
pivotted on a lever E, this lever is pivotted near its centre. on a fixed bracket, its
other end being hinged to a rod, fixed to the iron core M of the series solenoid A.
On the core N of the shunt solenoid B is hinged the end of another lever F pivotted
at g on a fixed bracket, near the other end of this lever is attached a weight sufficient
to overcome the weight of the core N, at h on this lever is pivotted a piece k to carry
the two rods a a, hanging downwards. the lower ends of these rois, are hinged to the
ends of two pairs of levers. c c, these levers point inwards crossing each other, and
are jointed at the middle, on the top side of these levers and between each pair, are
fixed two projections bb, These projections may be grooved pulleys as shown in Fig 4,
these pulleys may be smooth or milled or knurled either crossway or round the
circumference of the pulleys. these pulleys or projections may be fixed on the bottom
side of these levers. as in Fig 3. when the top ends of these levers are raised or
the bottom ends lowered the projections move together and clutch the flexible cord f,
which passes in the centre between these pairs of levers. as shown in Fig 4. under
these levers is placed a lever or rocking bar II with projections on which the bottom

page_text: ends of the levers c c, may rest this lever is pivotted at d its other end being under
and held down by the core M.
The action of the lamp is as follows when no current is passing the bottom end of
the core M. rests on the lever H. pressing it down by its weight, thus raising the
other end, and also the bottom ends of the levers c c, to which the clutches bb, are
attached, thus throwing them clear of the flexible cord f. and allowing the carbons to
move together, at the same time the lever E hinged to the rod attached to the core M.
is held so that the pulley C is level with the pulley D. The core N of the shunt
solenoid. B being held up by the action of the weight G holds the top ends of the
levers cc, in such a position that a slight downward movement of the lever H causes
the clutches bb, to grip the flexible cord. f.
When the current is turned on the series core M is attracted upwards. releasing the
lever H thus allowing the bottom ends of the clutch levers cc, to fall, causing the
clutchs 6 b, to grip the flexible cord and hold it fast, at the same time the core M
raises the lever E thus causing the pulley C to drop this allows the bottom carbon to
fall away from the top carbon thereby striking the arc, As the carbons burn away the
resistance of the arc increases bringing the shunt solenoid B into action attrating its
core N down-wards and with it the lever F the rods a a, and the clutch levers c c,
until the bottom ends of these clutch levers rest on the projections on the lever H.
opening the clutches and releasing the flexible cord, thus allowing the carbons to
move toward each other and restablishing the proper length of arc The force of
gravity caused by the weight G and the pull exercised by the shunt solenoid B thus
continually balancing each other with the result that a constant length of arc is
maintained.
I propose to use as a modification the arrangement, of the shunt solenoid B with
the core N lever F counterweight G rods a a, clutch levers. cc, as described above
and shown in Fig 1. with the exception of the coil A core M and levers E and H the
pulley C being pivotted on a fixed bracket, and the projection m and n as shown in
Fig 2. being used instead of the projection on the lever H.-seperate as a shunt
lamp.
I propose to use if prefered another arrangement. as shown in Fig 2. the
counterweight being reduced the core N projects through the bottom of the shunt
solenoid B. at the top end of the core N is fixed a rod, hinged to the lever F. this
lever is pivotted on a fixed bracket 1, at h is pivotted the piece k. carrying the
rods a a, and clutch levers c c, the action of the clutch levers and clutches is the same
as in Fig 1 but the core N is attracted upwards instead of downwards
I propose to use as a further modification the lever F counterweight G. rods a a,
and clutch levers c c, as shown in Fig 1 and used as a shunt lamp., the core N being
attached to the lever F as shown in Fig 2 and the counterweight reduced so as to
allow the core to project through the bottom of the solenoid when no current is
passing, this solenoid being in series with the circuit in which the lamp is placed
when the current is turned on the core is attracted upwards. carrying with it the
lever. F rods a a, clutch levers cc, causing the clutches to grip the flexible cord f
and raising it thereby striking the arc, as the carbons burn away the resistance of
the arc increases and the current decreases allowing the core with its levers, to fall
down thus releasing the clutches and allowing the flexible cord to slip through and
the carbons to move towards each other, thus maintaining a constant length of arc
I propose to use as a modification of clutch levers. as shown in Fig 3 in elevation,
and in plan in Fig 4. Instead of using the projections m and n, as in Fig 2 I may
use a frame S. carrying two pins pp, passing through slots in the ends of the clutch
levers this keeps the clutch levers in position if the lamp is laid on its side the sides
of these slots rubbing on the pins being Sloped, as also ends of levers as shown
in Figs 1 and 2. to assist in spreading the levers apart and opening the clutches.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is.-
1 An electric arc lamp with the mechanism for striking the arc, and for

page_text: maintaining a constant length of arc substantially as described and shown
in Fig 1.
2 An electric arc lamp with the mechanism for maintaining a constant length of
arc as a shunt lamp. substantially as described and shown in Fig 1.
3 An electric arc lamp with the mechanism for maintaining a constant length of
arc substantially as described and shown in Fig 2.
4 An Electric are lamp. with the mechanism for striking the arc. as in Fig 1 in
conjunction with the mechanism for maintaining a constant length of arc as in Fig 2
substantially as described and shown.
5 An electric arc lamp with the mechanism for maintaining a constant length of
arc as described and shown in Fig 1. but used with a series coil thus striking the arc
and maintaining a constant length of arc substantially as described and shown.
6 A form and arrangement of clutch levers substantially as described and shown
on Figs 3 and 4.
7 Å flexible cord on which the clutches work of braided wire of any metal a
flexible cord of any nonmetallic material with or without a core of the same material,
or a flexible cord with a braided or stranded metallic core and a non-metallic braided
covering substantially as described.