Year: 1888

page_text: Date of Application, 3rd July, 1888
Complete Specification Left, 26th Mar., 1889
Complete Specification Accepted, 27th Apr., 1889
We, GROSVENOR PORTER LOWREY, Counsellor-at-Law, of No. 121 Madison Avenue,
in the City of New York, United States of America, GEORGE FREDERICK SEWARD,
Vice President of the Fidelity and Casualty Company at No. 214 Broadway, in said
City of New York, and THOMAS LEOPOLD WILLSON, Electrician, of No. 163 Joralemon
Street in the City of Brooklyn, in the State of New York, United States of America,
do hereby declare the nature of this invention to be as follows:-
The invention relates more especially to machines of the Gramme type, and the
improvements are embodied in the special construction of the armature, and in the
relation of the brushes therewith, also in the special form of the field magnets and frame
of the machine, in the details of the brush-holders, in the driving connection between
the armature and its shaft, and in several minor features hereinafter detailed. The
invention relates to that principle of construction in which the armature instead of
being wire-wound, as usual, is constructed of segmental copper bars arranged in two
circles, one inside and one outside the iron core, and connected at the ends in spiral
order, forming a continuous spiral of copper segments around the iron core, the
segments being of course insulated by interposed strips of insulation.
Heretofore all armatures of this class have been either provided with commutators
in the usual way, one end of the copper segments being connected with the segments
of the commutator, or where a commutator is omitted the brushes have been arranged
to bear on the inside of the armature or against the inner circle of segments, which is
a comparatively contracted, inconvenient and inaccessible position. In the improved
machine we arrange the brushes to bear directly upon the outer circle of segmental
bars on the periphery of the armature at opposite points in the spaces between the two
externally-embracing and radially-approaching pole-pieces. This arrangement forms
practically a new and improved type of machine having the great advantage of extreme
compactness and solidity, with strength, capacity, cheapness and durability, for by this
arrangement the usual commutator is not only entirely eliminated, but the brushes are
arranged on the commutating periphery of the armature itself, in the gaps between
the pole pieces, which is the most safe, accessible and convenient arrangement, and

page_text: ono which provides a large and practically indestructible commutating surface to
receive the brushes, while all the parts and connections of the usual commutator are
entirely dispensed with, and great space, weight and cost thus saved. The invention
therefore consists partly in the loading feature abovo outlined, and also in the special
manner of connecting the two rows of segmental bars in the armaturo; in a novel
form of frictional driving connections between the armature and its shaft, in a device
to prevent the independent revolution of the armature on the shaft, in the special form
of the brush-holders and adjusters, and in the form of the field-magnet frame and the
relation of the armature therewith, as hereinafter fully set forth.
In the drawings annexed,
Fig. 1 presents a front elevation of the improved machine, and Fig. 2 gives an ond
elevation thereof.
Fig. 3 is a vertical cross-section on line 3--3 of Fig. 1, showing the armature in
end elevation.
Fig. 4 is a longitudinal section of the armature.
Fig. 5 is an enlarged cross-section of a peripheral fragment of the armature,
showing the arrangement of the segmental bars and intervening insulating strips.
Fig. 6 is an enlarged fragmentary perspective view of the armature, showing the
spiral coil arrangement of the segmental bars and the manner of connecting them at
the ends in spiral order, also showing the strips of insulation displaced.
Fig. 7 is an enlarged section of the brush-holler and adjuster parallel to the
brush, and
Fig. 8 is a section of the same transverse to the brush.
Fig. 9 shows a modified detail of the armature.
Referring to Figs. 1, 2 and 3, a b c d indicate the structural frame of the machine,
which also forms the frame of the field-magnets, and is made in the form of a simple
open rectangular frame, which is longer vertically than horizontally, the shorter sides
or ends being at top and bottom of the machine. The lower end a is flared or
broadened all around, and forms the base of the machine. At the middle of the upright
sides are formed the solid journal boxes e, in which each end of the armature
shaft y is mounted, which shalt thus extends transversely through the middle of the
frame, as best seen in Figs. 1 and 2, and is provided with the driving pulley 7 on one
end. On this armature shift midway within the frame is mounted the armature B, which
revolves between the curved pole-pieces which embrace the armature at top and
bottom, and are secured to the magnet coresk which project from the ends a d
inwardly and radially toward the armature, as best seen in Figs. 1 and 3. These cores
are wound with the exciting coils between the ends of the frame and the pole-pieces, as
shown; the winding in the drawing being shown as compound; coarse coils i being
placed near the pole-pieces and situated in the direct or working circuit, while the fine
coils are placed on the outer ends of the cores and situated in a shunt according to
the well-known system of compound winding. This general arrangement of the
magnet-frame, coils, shaft and armature is very compact, strong and simple, and the
neutral section of the magnet frame serves as the supports for the armature-shaft, no
separate supports being required, while the armature, magnot-coils etc. are all enclosed
within the frame, and as the frame is preferably cast in one piece, as illustrated in the
drawing, forming an integral frame, this imparts great solidity and steadiness to the
entire machine, which conduces to the smooth and easy running of the armature when
in operation.
The armature is of novel construction, as is best shown in Figs. 3, 4, 5 and 6. It
is of the Gramme or annular type, and consists of a core-ring m of iron wire (sec
Figs. 4 and 5) embraced by an inner and an outer circle of segmental copper bars n
running transversely to the core, or nearly parallel with the armaturo shaft, as seen in
Figs. 3, 4 and 5, and connected at the ends in spiral order, as will be understood from
Fig. 6, thus forming a continuous copper spiral about the iron core on the well-known
principle of the Gramme ring. Suitable insulation o, see Figs. 4 and 5, is interposed
between the iron core and the copper segments, and the segments are individually
insulated by interposed strips of mica p, as best seen in Figs. 5 and 6, which thus not
:

page_text: only insulate the cores or segments, but render the construction fireproof and durable.
The copper segments in the inner circle are made necessarily thinner than the outer
segments owing to the radial contraction, as seen in Fig. 5, but to compensate for this
they are made somewhat wider than the outer segments so as to possess about the same
mass or conductivity, as will be readily understood from Figs. 5 and 6. The segments
are connected at the ends in a very strong and simple manner, which consists
in scarfing or recessing the ends of the seginents to about half their thickness,
as shown clearly in Fig. 6, and inserting in the scarf or recess fl.it strips of
copper of about half the thickness of the segments, so as to be flush with
the sides of the segments but much wider so as to have about the same con-
ductive mass
as the segments, as well shown in Fig. 6. These strips are
preferably soldered into the scarfed ends of the segments, but may be secured
thereto by any other suitable means. Where the segments are sufficiently thick they
can be slit in the middle as seen in Fig. 9, and the flat strip inserted and secured in
the slit, but a thin segment is best scarfed on one side as this operation leaves a greater
thickness of stock for the joint, and is thus a better and simpler method for thin
segments. The insulating or mica strips p are sufficiently long to extend the full
length of the segments between the sides of the segments and the ends of connecting
strips r, and do not need to extend radially down into the spaces between the middle
of the connecting strips r, which spaces, as seen in Fig. 6 and at in Fig. 5, are
about twice the width of the space between the segments, and are free and open to the
air and need no insulation.
The armature thus made up forms a compound metallic ring of great strength and
density, the arched segments of copper both inside and outside the iron core being
bound firmly in place by the connecting strips ", thus forming a structure of great
solidity and compactness in which no space is wasted as is the case with the wire-
wound armature, and yet one in which the insulation is introduced in the cheapest and
simplest manner, while the amount of copper conductor is very large in proportion,
and hence the capacity of the armature is very high and its resistance very low, thus
forming a structure peculiarly adapted for large machines for currents of great power
or quantity.
The ring or essential portion of the armature is rotatively engaged with the
armature shaft in the manner best shown in Figs. 4 and 3. Within the ring are
placed the two sections of a split or divided friction pulley 4, and an interposed elastic
insulation s, which is preferably a band of leather which not only insulates the
armature from the split pulley but also forms an elastic frictional engagement between
the two. The interior of the split pulley is formed with opposite tapers or conical
inclines, as seen in Fig. 4, and to these are fitted two similarly tapering or we:lging
hubs or nuts tt, which respectively engage a right and left hand thread on a screw-
sleeve which is keyed to the armature driving-shaft y. Now referring to Fig. 4,
it will be seen that the torsional driving strain on the shaft and screw-sleeve which
turns in the direction of the arrow will tend to screw the wedging nuts or hubs t t¹
together, and thus diverge or expand the two sections of the split pulley against the
armature, thereby making a firm rotative engagement with the armature, which will
constantly tend to tighten in use, and consequently as fast as the insulations shrinks
the pulley will be automatically expanded by the torsional driving strain transmitted
from the shaft through the wedging screw devices, thus preventing any looseness duo
to such shrinkage. The action of these wedging devices is self-centering so that the
armature is also kept in a central or balanced position on the shaft g. It will be
apparent that if the armature should turn in the same direction as the shaft, as for
example by its own momentum after the shaft was stopped, the armature would then
tend to loosen the connection. This independent rotation of the armature, however,
is prevented by a ratchet connection between the shaft and armature, which engages
in the direction in which the armature would turn forwardly on the shaft, but slips in
the direction in which the shaft would turn in the same direction in the armature.
This ratchet connection is preferably of a frictional ratchet kind, or consists simply of
two toggle-like friction pawls u u, as seen in Figs. 3 and 4, which are pivoted to a

page_text: collar on the shaft and extend out in an oblique position to engage the rim of
the split friction-pulley 1, little springs u¹ acting to keep the pawls in constant
engagement.
A peculiar and very advantageous fenture of the machine lies in the position in
which the brushos are arranged in relation with the armature described, and in the
manner in which they are mounted and manipulated. Referring to Figs.
2 and 3,
the brushes are arranged to bear directly upon the outer segments on the extreme
periphery of the armaturo and in the gaps or spaces between tho pole-pieces at
opposite sides of the armature, the periphery of which is turned off true. Hence the
armature forms in itself the commutator, thus entirely eliminating the usual separate
commutator and therefore not only greatly reducing the weight of metal and the
number of parts and the cost of the structure, but saving nearly one third in the
axial size or width of the machine, which is a great gain in compactness besides
simplifying the entire design of the machine. Furthermore the described position of
the brushes on the periphery of the armature between the external and radially
approaching pole-pieces, is obviously of great advantage, as this is the most convenient
and accessible position in which the brushes could be placed, and as the brushes of a
dynamo are the parts which require continued adjustment and inspection, and the
action of which is an index to the proper working of the machine and circuit, their
arrangement as described is most important, as they are thus brought to the front of
the unachine, external to everything else, which is the most convenient to the atton-
dant and the safest and best situation in both a mechanical and electrical sonso.
Another great advantage of the segmental commutating armature with the externally
placed brushes is that a very broad and extended commntating surface is provided
for the brushes to bear against, and honce the commutating surface will have
great range of wear and great durability, and will admit a whole gang or series
of brushes, a feature particularly suited for large and powerful machines, to which
the invention is especially applicable. Another important advantage of this armature
with its externally placed brushes is that the two opposite brushes are thus placed
at such a great distance apart as to preclude the possibility of any loss from short
circuits from one segment to the other or flashing around the commutating periphery
from one brush to another, as commonly happens with the small separate commun-
tator where the segments are narrow and the brushes comparatively close together.
It will be readily understood that with this type of armature the brushes might
be arranged to bear on the ends of the segments or strips at the ends of the
ring, or they might be arranged to bear on the concave interior of the ring, but
such an arrangement of the brushes any where on the interior of the machino or
inside the frame, would be open to most serious objections, being inconvenient,
inaccessible, and unsafe, and would provide but a very limited brush-bearing
surface.
In Fig. 1 we show the machine fitted with two brushes on each side of the
armature, but one or more may of course bo used, preferably two or more in all
cases. Each brush projects from a brush-holder y of about the usual construction,
which is mounted on a fixed but adjustable supporting bar w, which extends across
the face of the machine at front and back parallel to the axis of the armature, and
is sccured at each end in small brackets w, which have a slotted base which abuts
against the sides be of the frame, and is secured thereto by the studs . It is
therefore obvious that by loosening the studs 102, the brackets may be adjusted up or
down on the frame, and hence the bars w with their brushes may be thus adjusted
tangentially up or down in relation to the commutating periphery of the armature.
Besides this tangential adjustment of the brushes the brush-holders are capable of
partial rotation on the bars w, as seen best in Fig. 7, thus providing a radial adjustment
of the tip of the brush to and from the commutating surface, as is usual in brush-
holders. That is, referring to Figs. 7 and 8, the brush-holder y is rotatively mounted
between two collars on the sleeve y' which is secured to the bar c. A. coiled spring y
seen bost in Fig. 7, is fixed at one end to the sleeve y' and bears at the opposite end
on the brush-holder, thus tending constantly to press the tip of the brush against the

page_text: communicating surface with an even and regular pressure, which is important to the
efficient action of the brush. By rotating the brush-holder away from the commu-
tating surface into the position shown by dotted lines in Fig. 7, a small spring-bolt y³
will spring into engagement with a recess on the brush-holder, and thus hold the
brushes safely in their retracted position, (shown by dotted lines in Fig. 7), when the
machine is not in operation, or when it is desired to throw any brush out of action.
The brushes are of course longitudinally adjustable under the gib 3 and clamp-screw 5
in the brush-holder in the usual vanner, as seen in Fig. 7, to set the brush forward
or back for wear or position. When it is desired to put the brush again in action thie
spring-bolt y is withdrawn and the spring y³ will return the brush to the commutating
surface and hold the same evenly and elastically thereon.
.20
The brush-supporting bars ww are insulated from the brackets w¹ by the non-
conducting bushings w³. We prefer to extend all the circuit connections of the
machine to and from the said bars, which is a very simple and convenient arrange-
ment and brings all the connections in sight and accessible on the exterior of the
machine. The circuit connections of the machine are made as follows. The terminal
binding-posts of the machine are arranged in the upper corners of the frame, as
fully shown in Figs. 1 and 3, and are heavily insulated therefrom as indicated. The
positive conductor 8 (see Fig. 1) extends from the positive brush-bar w to the positive
post, and the current, flowing thence in the external or working circuit back to
the opposite post, divides at this post between the wires 10 and 11, and thus goes
to one end of the main field coils ii, and thence by wires 12 and 13 back to the
negative brush-bar w. The wires 1-4 and 15 connect each end of the upper shunt-
coil to the positive and negative brush-bars respectively, and the wires 16 and 17
connect the ends of the lower shunt-coil with the respective bars. The circuit wires
are secured to the brush-bars by simply inserting the naked ends of the wires in
socket-holes bored through the bars in which they are held by clamp-screws, as
illustrated in Fig. 1.
The sleeve y¹ with its brush-holder and brush is longitudinally adjustable on the
axial bar w, so that the brush may be set to bear on any desired longitudinal part of
the armature.
In the drawings we have shown the improvements as applied to a generator and in
which the field magnets have a compound winding, but it is obvious that the invention
is equally applicable to motors, and the field winding may be entirely of the shunt,
series, or other kind adopted in electrical practice.
Dated the 14th day of June 1888.

page_text: Improvements in Dynamo Electric Machines and Electro Motors.
We, GROSVENOR PORTER LOWRET, Counsellor-at-Law, of No. 121 Madison
Avenue, in the City of New York, United States of America, Gizonun FREDERICK
SEWARD, Vice President of the Fidelity and Casualty Company at No. 214 Broadway,
in said City of New York, and THOMAS LEOPOLD WILLSON, Electrician, of No. 163
Joralemon Street in the City of Brooklyn, in the State of New York, United
States of America, 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:—
The invention relates more especially to machines of the Cramme ring type, and
the improvements are embodied in the special construction of the arumture, and in
the relation of the brushes therewith, also in the special form of the field magnets and
frame of the machine, in the details of the brush-holders, in the driving connection
between the armature and its shaft, and in several minor features hereinafter detailed.
The invention relatos to that type of construction in which the armature, instead of
being wire wound, as usual, is constructed of segmental copper bars arranged in two
circles, one inside and one outside the iron core, and connected at the ends in spiral
order, forming a continuous spiral of copper segments around the iron core, the
segments being of course insulated by interposed strips of insulation.
Heretofore all armatures of this class have been either provided with commutators
in the usual way, one end of the copper segments being connected with the segments
of the commutator, or where a commutator is omitted the brushes have been arranged
to bear on the inside of the armature or against the inner circle of segments, which is
a comparatively contracted, inconvenient and inaccessible position. In the improved
machine we arrange the brushes to bear directly upon the outer circle of seginental
bars on the periphery of the armature at opposito points in the gaps or spaces:
between the two externally-embracing and radially-approaching pole-pieces. This
arrangement forms practically a new and improved type of machine having the great
advantage of extreme compactness and solidity, with strength, capacity, cheapness
and durability, for by this arrangement the usual commutator is not only entirely
eliminated, but the brushes are arranged on the commutating periphery of the
armature itself, in the gaps between the pole pieces, which is the most sufo, accessible
and convenient arrangement, and one which provides a large and practically
indestructible commutating surface to receive tho brushes, whilo all the parts and
connections of the usual commutator are entirely dispensed with, and great space,
weight and cost thus saved. The invention therefore consists partly in the leading
feature above outlined, and also in the special manner of connecting the two rows
of segmental bars in the armature; in a novel form of frictional driving connections
between the armature and its shaft, in a device to prevent the independent revolution
of the armature on the shaft, in the special form of the brush-holders and adjusters,
and in the form of the field-magnet frame and the relation of the armature therewith,
as hereinafter fully set forth and claimed.

page_text: In the drawings accompanying our Provisional Specification.
Fig. 1 represents a front elevation of the improved machine, and Fig. 2 gives an
end elevation thereof.
Fig. 3 is a vertical cross-section on line 3--3 of Fig. 1, showing the armature in
end elevation.
Fig. is a longitudinal section of the armature.
Fig. 5 is an enlarged cross-section of a peripheral fragment of the armature,
showing the arrangement of the segmental bars and intervening insulating strips.
Fig. 6 is an enlarged fragmentary perspective view of the armature, showing
the spiral coil arrangement of the segmental bars and the manner of connecting
them at the ends in spiral order, also showing the strips of insulation displaced.
Fig. 7 is an enlarged section of the brush-holder and adjuster parallel to the brush,
and
Fig. 8 is a section of the same transverse to the brush.
Fig. 9 shows a modified detail of the armature.
Referring to Figs. 1, 2 and 3, a b c d indicate the structural frame of the
machine, which also forms the frame of the field-magnets, and is made in the form
of a simple open rectangular frame, which is longer vertically than horizontally, the
shorter sides or ends being at top and bottom of the machine. The lower end a
is flared or broadened all around, and forms the base of the machine. At the middle
of the upright sides b c are formed the solid journal boxes ef, in which each end of
the armature shaft g is mounted, which shaft thus extends transversely through the
middle of the frame, as best seen in Figs. 1 and 2, and is provided with the driving
pulley on one end. On this armature shaft midway within the frame is mounted
the armature B, which revolves between the curved pole-pieces h h which embrace
the armature at top and bottom, and are secured to the magnet cores & ¹ which
project from the ends da inwardly and radially toward the armature, as best seen
in Figs. 1 and 3. These cores are wound with the exciting coils between the
ends of the frame and the pole-pieces, as shown. The winding in the drawing is
compound, coarse coils ii being placed near the pole-pieces and situated in the
direct or working circuit, while the fine coils jj are placed on the outer ends of the
cores and situated in a shunt, according to the well-known system of compound
winding. This general arrangement of the magnot-frame, coils, shaft and armature
is very compact, strong and simple, and the neutral section of the magnet frame
serves as the support for the armature-shaft, no separate supports being required,
while the armature, magnet-coils etc. are all enclosed within the frame, and as the
frame is preferably cast in one piece, as illustrated in the drawing, forming an
integral frame, this imparts great solidity and steadiness to the entire machine, which
conduces to the smooth and easy running of the armature when in operation.
The armature is of novel construction, as is best shown in Figs. 3, 4, 5 and 6. It
is of the Gramme or anuular type, and consists of a core-ring m of iron wire (see
Figs. 4 and 5) embraced by an outer and an inner circle of segmental copper
bars nn, running transversely to the core, or nearly parallel with the armature shaft,
as seen in Figs. 3. 4 and 5, and connected at the ends in spiral order, as will be
understood from Fig. 6, thus forming a continuous copper spiral about the iron
core on the well-known principle of the Gramme ring. Suitable insulation o, see
Figs. 4 and 5, is interposed between the iron core and the copper segments, and
the segments are individually insulated by interposed strips of mica p, as best seen
in Figs. 5 and 6, which thus not only insulate the cores or segments, but render
the construction fire-proof and durable. The copper segments in the inner circle
are made necessarily thinner than the outer segments owing to the radial contraction,
as seen in Fig. 5, but to compensate for this they are made somewhat wider than
the outer segments so as to possess about the same transverse area or conductivity,
as will be readily understood from Figs. 5 and 6. The segments are connected at
the ends in a very strong and simple manner, which consists in scarfing or recessing
the ends of the segments to about half their thickness, as shown clearly in Fig. 6,
and inserting in the scarf or recess flat strips of copper r of about half the thickness

page_text: are
of the segments, so as to be flush with the sides of the segments but much wider,
so as to have about the same conductive mass as the segments. These strips
preferably soldered to the scarfed ends of the segments, but may be secured thoreto
by any other suitable means. Where the segments are sufficiently thick they can
be slit in the middle as seen in Fig. 9, and the flat strip r inserted and secured in
the slit, but a thin segment is best scarfed on one side as this operation leaves a
greater thickness of metal for the joint, and is thus a better and simpler method for
thin segments. Tho insulating or mica strips are sufficiently long to extend the
full length of the segments between the sides thereof and the ends of the connecting
strips r, and do not need to extend radially down into the spaces between the middle
of the connecting strips r, which spaces, as seen in Fig. 6 and at rr in Fig. 5, are
about twice the width of the space between the segments, and are free and open to
the air so that they need no insulation.
The armature thus made up forms a compound metallic ring of great strength and
density, the arched segments of copper both inside and outside the iron core being
bound firmly in place by the connecting strips r, thus forming a structure of great
solidity and compactness in which no space is wasted as is the case with wire-wonnd
armatures, and yet one in which the insulation is introduced in the cheapest and
simplest manner, while the amount of copper conductor is very large in proportion,
and hence the capacity of the arinature is very high and its resistance very low,
thus forming a structuro peculiarly adapted for large machines for currents of great
volume or quantity.
"
The ring or essential portion of the armature is rotatively engaged with the
armature shaft in the manner best shown in Figs. 8 and 4. Within the ring are
placed the two sections of a split or divided friction pulley 1, and an interpo.al
elastic insulations, which is preferably a band of leather, so as not only to insulate
the armature from the split pulley but also to form an elastic frictional engagement
between the two. The interior of the split pulley is formed with opposite tapers or
conical inclines, as seen in Fig. 4, and to these are fitted two similarly tapering or
wedging hubs or nuts, which respectively engage a left and right hand thread
on a screw-sleeve t which is keyed to the armature driving-shaft g. By referring to
Fig. 4, it will be seen that the torsional driving strain on the shaft and screw-sleero
which turn in the direction of the arrow, will tend to screw the wedging nuts or
hubs together, and thus diverge or expand the two sections of the split pulley
against the armature, thereby making a firm rotative engagement with the
armature, which will constantly tend to tighten in use, and consequently as
fast as the insulation s shrinks the pulley will be automatically expanded by the
torsional driving strain transmitted from the shaft through the wedging screw
devices, thus preventing any looseness due to such shrinkage. The action of these
wodging devices is self-centering, so that the armature is also kept in a central or
balanced position on the shaft g. It will be apparent that if the armature should
turn in the same direction as the shaft, as for example by its own momentum alter the
shaft was stopped, the armaturo would then tond to loosen the connection. This
independent rotation of the armature, however, is prevented by a ratchet connection
between the shaft and armature, which engages in ilu direction in which the arma-
ture would turn forwardly on the shaft, but slips in the direction in which the shaft
would turn forwardly within the armature. This ratchet connection is preferably of
a frictional ratchet kind, consisting simply of two togglo-liko friction jawls, as
seen in Figs. 3 and 4, which are pivoted to a collar r fixed on the shaft g and extend
out in an oblique position to engage the rim of the split friction-pulley 4, little springs u
acting to keep the pawls in constant engagement.
The most important and advantageous feature of the machine lies in the position
in which the brushes are arranged in relation with the armature described, and in
the manner in which they are mounted and manipulated. Referring to Figs. 1, 2
and 3, the brushes are arranged to bear directly upon the outer segments on the 5
extreme periphery of the armature and in the gaps or spaces between the pole-
pieces at opposite sides of the armature. Hence the armature, the periphery of

page_text: which is turned off true, forms in itself the commutator, thus entirely eliminating the
usual separate commutator and therefore not only greatly reducing the weight of
metal and the number of parts, and consequently the cost of the structure, but
saving nearly one third in the axial size or width of the machine, which is a great
gain in compactness besides simplifying the entire design of the machine. Further-
more the described position of the brushes on the periphery of the armature between
the external and radially approaching polo-pieces, is obviously of great advantage, as
this is the most convenient and accessible position in which the brushes could be placed,
and as the brushes of a dynamo are the parts which require most frequent adjustment
and inspection, their arrangement as described is highly advantageous, as they are
thus brought to the front of the machine, external to overything else, into the most
convenient position for the attendant and the safest and best situation in both a
mechanical and electrical sense. Another great advantago of the segmental commu-
tating armature with the externally placed brushes is that a very broad and extended
commutating surface is provided for the brushes to bear against, and hence the
commutating surface will have great range of wear and great durability, and will
admit a whole gang or series of brushes, a feature particularly suited for large and
powerful machines, to which the invention is especially applicable. Another important
advantage of this armature with its externally placed brushes is that the two opposite
brushes are thus placed at such a great distance apart as to preclude the possibility
of any flashing around the commutating periphery from one brush to another, as
commonly happens with the small separate commutator where the segments are narrow
and the brushos comparatively close together.
In Fig. 1 the machine is shown fitted with two brushes on each side of the armature,
but one or more may of course be used, preferably two or more in all cases. Each
brush projects from a brush-holder y of about the usual construction, which is mounted
on a fixed but adjustablo supporting bar w, which extends across the face of the machine
at front and back parallel to the axis of the armature, and is secured at each end in
small brackets 10', which have a slotted base which abuts against the sides bc of the
frame, and is secured thereto by the studs w. It is therefore obvious that by
loosening the studs w², the brackets may be adjusted up or down on the frame, and
hence the hars w with their brushes may be thus adjusted tangentially up or down in
relation to the commutating periphery of the armature. Besides this tangential
adjustment of the brushes the brush-holders are capable of partial rotation on the
bars w, as seen best in Fig. 7, thus providing a radial adjustment of the tip of the
brush to and from the commutating surface, as is usual in brush-holders. That is,
referring to Figs. 7 and 8, the brush-holder y is rotatively mounted between two collars
on a sleeve y' which is secured to the bar w. A coiled spring y³, seen best in Fig. 7,
is fixed at one end to the sleeve y' and bears at the opposite end on the brush-holder,
thus tending constantly to press the tip of the brush against the communicating
surface with an even and regular pressure. By rotating the brush-holder away from
the commutating surface into the position shown by dotted lines in Fig. 7, a small
spring-bolt y will spring into engagement with a recess on the brush-holder, and
thus hold the brushes safely in their retracted position, (shown by dotted lines in
Fig. 7), when the machine is not in operation, or when it is desired to throw any
brush out of action. The brushes are of course longitudinally adjustable in the usual
manner under the gib 3 and clamp-screw 5 in the brush-holder, as seen in Fig. 7, to
set the brush forward or back for wear or position. When it is desired to put the
brush again in action the spring-bolt y is withdrawn and the spring y² will return
the brush to the commutating surface and hold the same evenly and elastically
thereon.
The brush-supporting bars w ware insulated from the brackets by the non-
conducting bushings. We prefer to extend all the circuit connections of the
machine to and from the said hars, which is a very simple and convenient arrangement
and brings all the connections in sight and accessible on the exterior of the machine.
The circuit connections of the machine are made as follows. The terminal binding-
posts of the machine are arranged in the upper corners of the frame, as fully
B

page_text: shown in Figs. 1 and 3, and are heavily insulated therefrom as indiented. The positive
conductor S (so Fig. 1) extends from the positive brush-hare to the positive post,
and the current, flowing thence in the external or working cirenit. back to the opposite
post, divides at this post bot ween the wires 10 and 11, and thus goes to one end
of the main field coils ii, and thenco by wires 12 and 13 lack to the negative
brush-har . The wires 14 and 15 connect each end of the upper shunt-coil to
the positive and negative brush-bars respectively, and the wires 16 and 17 connect
the ends of the lower shunt-coil with the respective bars. The circuit wires aro
secured to the brush-bars by simply insorting the naked ends of the wires in socket-
holes bored through the bars in which they are held by clamp-screws, as illustratol
in Fig. 1.
The sleeve y with its brush-holder and brush is longitudinally adjustable on the
axial bar to, so that tho brush may be set to bear on any desired longitudinal part of
the armature.
In the drawings we have shown the improvements as applied to a dynamo or
generator and in which the field magnets have a compound winding, but it is obvious
that the invention is equally applicable to motors, and the field winding may be
entirely of the shunt, sories, or other kind adopted in electrical practice.
Having now fully described and ascertained the nature of the said invention, and
in what manner the same is to be perforined, we declare that what wo claim is :—
1. A dynamo electric machine constructed with a commutating armature embraced
between the pole-pieces of the field-magnet, and having commutator brushes bearing
upon the portion of the periphery of the armature exposed in the gaps between
the pole-picces, substantially as hereinbefore specified.
2. A dynamo electric machine having a commutating armature and a field-magnet
constructed to leave the entire length of the armature exposed on opposite sides
between the pole-pieces, and commutator brushes arranged to bear upon the exposed
periphery of the armature in the polar gaps, substantially as specified."
3. A dynamo electric machine wherein a commutating armature is mounted with
its axis coincident with the plane of the field-magnot, whereby the portions of the
periphery of the armaturo, exposed in the gaps between the pole-pieces are on opposite
sides of the plane of the field-magnet, and commutator brushes bearing upon the
periphery of the armature within the polar gaps, whereby the brushes are conveniently
accessible upon the exterior of the machine, substantially as specified.
4. A commutating armature the entire length of which is exposed on its opposito
sides in the gaps between the pole-pieces of the fiull-magnet, in combination with
commutator brushes hearing against the periphery of the armature and so mounted as
to be adjustable longitudinally thereof in the polar gaps, substantially as specified.
5. The combination with a commutating armature and commutator brushes bearing
against it, of brush-holding bars extending parallel with the armature, and adjustable
supports for said bars, substantially as specified.
G. The combination with a commutating armature and commutator brushes bearing
against it, of brush holding bars extending parallel with the armature, and the brushes
adjustable longitudinally on said bars, substantially as specified.
7. The mounting of commutator brushes in brush-holders pivotally connected to
axes that are adjustablo tangentially relative to the commutating surfaco, substantially
as specified.
8. The combination with the positive and negative commutator brushes of positive
and negative conducting bars on which they are mounted, and which bars are insulated
from the supporting frame, and the circuit wires of the field-nungnet coils connected
to said bars, substantially as specified.
9. A commutating Gramme armaturo consisting of a tubular iron core, an inner and
outor circular row of longitudinal segmental conducting bars, with intervening strips
of insulating unatorial, and radial conducting bars at the ends of tho armature con-
nected to the inner and outer bars to form a continuous spiral, and with their onds
sunk into rocessos in the unds of the longitudinal bara, substantially as specified.

page_text: 10. In a commutating Grammo armature of the described type, the avoidance of
insulation between the radial conducting bars at the ends of the armature, by making
said bars thinner than the outer and inner longitudinal bars, so that they are held out
of contact with each other by the ends of the interposed outer and inner insulating
strips, substantially as specified.
11. In combination with the expanding scrow connection for mounting the armature
ring on its shaft, constructed to expand by the forward rotation of the shaft in the
armature, a clutch adapted to prevent the forward rotation of the armature relatively
to the shaft, whereby the accidental loosening of the connection is avoided, substantially
as specified.
Dated this Ofth day of Mauch 1000