IMPROVEMENTS IN AND APPLICABLE TO DYNAMO-ELECTRIC, MAGNETO-ELECTRIC AND SIMILAR MACHINES
Year: 1883

page_text: LETTERS PATENT to Leonard Falkner Lamkin, of Page Street Westminster,
in the county of Middlesex [Electrician] for an Invention of IMPROVEMENTS
IN AND APPLICABLE TO DYNAMO-ELECTRIC, MAGNETO-ELECTRIC AND SIMILAR
MACHINES
PROVISIONAL SPECIFICATION left by the said Leonard Falkner Lamkin
at the Office of the Commissioners of Patents on the 29th June 1883.
LEONARD FALKNER LAMKIN of Page Street Westminster in the county of
Middlesex Electrician IMPROVEMENTS IN AND APPLICABLE TO DYNAMO-ELECTRIC,
MAGNETO-ELECTRIC AND SIMILAR MACHINES
These improvements relate to Dynamo-Electric Magneto-Electric and similar
machines and have for their object to control the Electro Motive Force of the
current generated
In such machines as at present constructed, the brushes are generally so arranged
that they are in contact with diametrically opposite bars of the commutator and
are capable of simultaneous movement around the commutator in such a manner
that their relative positions aro maintained
These improvements consist in providing means whereby the positions of the
brushes may be changed relatively to each other either by hand or by an automatic
device in such a manner that either the maximum or any desired lower difference
of potential may be obtained
In carrying out this invention the brush carrier has one brush holder fixed. The
other brush holder may be borne in a slot formed in the brush carrier-This slot
forins the arc of a circle having its centre in the armature axis-To secure the
moveable brush holder in any position that portion of it passing through the slot
may be provided with a collar and nut between which the brush carrier may be
gripped-If it is desired to regulate the position of the movable brush auto-
matically, the brush holder may be connected to a rod or lever another portion of
the rod or lever being connected to a plunger of iron working within a solenoid-
Prins 11

page_text: This solenoid may be included either in the main or in a shunt circuit and the
position of the plunger should be regulated by a spring in such a manner that when
the current pos-esses the maximum Electro Motive Force the brush holder is held
by the connecting rod or lever in such a position that the two brush contacts are
diametrically opposite-Should this Electro Motive Force be exceeded the plunger
will be attracted into the solenoid the position of the moveable brush will be altered
and the Electro Motive Force will be reduced.
By means of these improvements there is no waste of energy, that is to say the
electric horse power is always at about the same ratio to the mechanical horse
power whatever electro motive force may be generated.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Leonard Falkner Lamkin in the Great Seal Patent Office on the
29th December 1883.
"
LEONARD FALKNER LAMKIN, of Page Street, Westminster, in the County of
Middlesex, 'IMPROVEMENTS IN AND APPLICABLE TO DYNAMO-ELECTRIC, MAGNETO-
ELECTRIC AND SIMILAR MACHINES,"
"
These improvements relate to dynamo-electric, magneto-electric and similar
machines and have for their object to control the electro-motive force of the current
generated so as to maintain an approximately constant ratio between the electric
horse power and the mechanical horse power; whatever electro-motive force may
be generated.
In such continuous current machines as at present constructed the brushes are
generally so arranged that they are in contact with diumetrically opposite bars of
the commutator and are capable of simultaneous movement around the commutator
in such a manner that their relative positions are maintained.
These improvements consist in providing means whereby the positions of the
brushes may be changed relatively to each other either by hand or by an automatic
device in such a manner that either the maximum or any desired lower difference
of potential may be obtained.
In carrying out this invention the brush carrier has one brush holder fixed. The
other brush holder may be borne in a slot formed in the brush carrier. This slot
forms the arc of a circle having its centre in the armature axis. To secure the
moveable brush holder in any position, that portion of it passing through the slot
may be provided with a collar and nut between which the brush carrier may be
gripped. Or the movable brush holder may be secured to a slotted sector having
its centre in the axis of the armature. If it is desired to regulate the position of
the movable brush automatically, the brush holder may be connected to a rod or
lever, another portion of the rod or lever being connected to a plunger of iron
working within a solenoid. This solenoid may be included either in the main or
in a shunt circuit, and the position of the plunger should be regulated by a spring
or equivalent device in such a manner that when the current possesses the maximum
electro-motive force the brush holder is held by the connecting rod or lever in
such a position that the two brush contacts are diametrically opposite. Should
this electro motive force be exceeded the plunger will be attracted into the solenoid,
the position of the movable brush will be altered and the electro motive force will
be reduced.
In the accompanying drawings which serve to illustrate the invention Fig. 1
represents an ordinary commutator with brush carrier and movable brush made
adjustable by hand; Fig. 2 represents a modification of the same, while Fig. 3.
represents an analogous arrangeinent in which the position of the movable brush is
controlled by a solenoid.
A represents a cross section of an ordinary commutator, B the brush carrier which
may be fixed to two stands or otherwise secured to the frame of the machine, C is
a fixed brush, C¹ a movable brush, the holder of which is adapted to slide in the
curved slot D and to be fixed therein by means of a screw and nut as illustrated by
Figs. 1 and 1; or the movable brush holder may be secured to a movable sector S
pivoted on the axis of the commutator and guided, if desired, by a fixed pin P.
as illustrated by Fig. 2. The position of the brush may be automatically controlled
by a solenoid E and an antagonistic spring F or equivalent devices. In the drawing
one end of the solenoid is connected with the holder of brush C by a link or rod H

page_text: provided with a nose h on which acts one end of the spring F secured at its other
end to the brush carrier.
Having now described my invention and in what manner the same is to be
performed, I wish it to be understood, that I do not limit myself to the exact
details shown by the drawings by way of example, as the same may be modified
without departing from iny invention, but that what I claim is :
1. In continuous current dynamo-electric and similar machines the combination
of a commutator with two brushes and with means for varying the relative position
of the brushes by hand, substantially as described.
2. In continuous current dynamo-electric and similar machines the combination
of a commutator with two brushes and with means for automatically regulating
the relative position of the brushes by the current generated in the machines,
substantially as described.
3. In continuous current dynamo-electric and similar machines the combination
of commutator A, with fixed brush C, movable brush C', guided concentrically to
the commutator, solenoid E excited by the current of the dynamo-machine or by a
shunt current of the same and adapted to control the position of the brush C¹ in
conjunction with an antagonistic spring F, or equivalent device substantially as
described.
In Witness whereof I, the said Leonard Falkner Lamkin have hereunto set my
hand and seal this 29th day of December A.D. 1883.