Improvements in Dynamo Electric Machines.
Year: 1893

page_text: Date of Application, 24th May, 1893
Complete Specification Left, 24th Feb., 1894-Accepted, 12th May, 1894
PROVISIONAL SPECIFICATION.
Improvements in Dynamo Electric Machines.
I, WILLIAM BROOKS SAYERS, of Glenwood, Bearsden, near Glasgow, in the
County of Dumbarton, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
la the Specification of Letters Patent granted to me dated 29th September 1891
No. 16572 I have described a construction of dynamo electric machine in which
the commutator strips are connected to the sections of the armature winding
through commutator coils in which an electro-motive force is set up when the
machine is running, the said coils being connected to the armature winding in such
a manner that each coil will have a backward lead with reference to the point
between sections of the armature winding to which it is connected when the machine
is running as a generator, and a forward lend when the machine is running as a
motor, and the commutator brushes being so arranged as to have a backward lead
when the machine is running as a generator and a forward lead when it is running
as a motor, the arrangement in each case being such that the armature current will
tend to increase the total magnetic flux and that the resultant E.M.F. induced in
any two of the commutator coils and in the section of the armature winding
that connects them will reverse or tend to reverse the current in the said section of
the armature winding and reduce to zero the current in the commutator coil
connected to the commutator strip that is about to leave the commutator brush at
the time when one of the said two commutator coils is under the horn of the field
magnet pole that is strengthened by the armature current and the other has passed
from under the same and the two corresponding strips of the commutator are
connected by a commutator brush.
Now my present invention has reference to further developments in dynamo
electric machines constructed and operating in the manner referred to, whereby in
addition to other advantages, such a machine can be used to run in either direction,
either as a generator or as a motor, without the necessity of providing it for this
purpose with two commutators as described in my said former Specification.
For this purpose instead of winding the commutator coils around the core of the
armature ring or drum, I arrange the said commutator coils longitudinally upon or
within the periphery of the armature and so that portions of the convolutions of
each of them will be located on opposite sides of a section of the armature
winding to one side of which one end of the coil is connected, the arrangement
being such that as each coil passes under the tip or born of a field magnet pole,
the portion of the coil which is in front of the said armature section will have
passed out from under said tip or horn and will therefore be inoperative, while the
portion which is behind the said armature section will be under the pole tip and
therefore operative in producing the resultant E.M.F. required to bring about the
reversal of the section in the manner described in my said former Specification.
It will thus be evident that in whichever direction the machine is running
(considering it as a generator) that portion only of the coil will be effectively
operative that is behind the armature section relatively to the direction of rotation,
and as one side of the coil is behind when the machine is running in one direction
and the other side when the machine is running in, the opposite direction, the
arrangement becomes reversible.
When the machine is used as a motor the foregoing reasoning holds except that
it is the portion of the commutator coil which is in front of the armature section

page_text: relatively to the direction of rotation which is operative and the portion which is
behind which is inoperative in whichever direction the machine may be running.
The commutator coils may advantageously be so arranged that the points at which
they are connected between the sections of the armature winding are located
midway between the side portions of such coils so that such portions will have an
equal lead in whichever direction the armature may rotate.
The
An
In order to make the improved commutator coils hereinbefore described more
powerfully operative for the purpose in view, I may construct the tips or horns of
the field magnet pole pieces (or keepers as they may be called when there is no
winding upon them), with recesses on the side next the armature, the width of each
recess being made approximately equal to the distance between the two portions of
each commutator coil. The magnetic density in the recess will be small compared
with that between the armature and polar surface in each side thereof.
result of this construction in the case of a generator is that the portion of a
commutator coil which is in front of the armature section to which it is connected
and also such armature section, will be opposite the recess at the time
when the portion of the commutator coil which is behind the said armature
section will be still in the part where the magnetic density is greatest.
E.M.F. will therefore be induced in the coil the direction of which (determined
by the relative directions of winding of the main coils and the commutator coils)
should be such as to cause the armature current to flow through this commutator
coil to the brush. When the commutator coil reaches the position in which its two
sides coincide approximately with the edges of the said recess, the E. M. F's induced in
the two sides of the coil will be equal and opposite. When the portion of the
commutator coil which is in front of the said armature section has passed from the
recess and into a position under the pole tip where the magnetic flux is denser,
the portion of the coil which is behind will have passed into a position opposite
the recess and consequently a resultant E.M.F. will now be generated in the coil
opposite in direction to that under the conditions first considered. It will now be
evident that if the commutator brushes are set so as to correspond with the portions
of the recesses, then of the two commutator coils on cach side concerned at the
moment when two commutator bars are connected under the brush, that
commutator coil which last became connected under the brush, will have a
resultant E.M.F. induced in it in such a direction as to cause the armature
current to flow through this commutator coil to the brush, while the other
commutator coil, which, of the two being considered-first became connected with
the brush, will have a resultant E.M.F. induced in it tending to stop the current
flowing through it from the armature, the result of these conditions being to bring
about the reversal of the armature section-at the ends of which are connected
the two commutator coils during the time in which the corresponding cominutator
bars are passing under the brush.
When the machine is required to run in either direction at will, recesses such as
described are formed in all the polar horns, the brushes being set so as to correspond
with those which are strengthened by the armature current.
In some cases 1 may wind insulated wire in the recesses formed in the polar
horns and over the outside of same, and connect up the coils so formed, either in
shunt or series, in order to control the magnetic flux through the projecting horu.
With the arrangement of commutator coils herein described the effect of the
current in the commutator coils is rather to increase the magnetic flux through the
armature, whereas in the arrangement described in my said former Specification
the action of the current in the commutator coils was to cancel part of the
advantageous magnetising effect of the armature current obtained when the brushes
are set with a backward lead.
Dynamo electric machines of the improved construction herein before described
when used as motors may advantageously be provided with brush holders carrying
radial commutator brushes and mounted so as to be free to move through an arc
limited by adjustable stops, the arrangement being such that assuming the armature

page_text: to have been running in one direction with the brushes arranged with a forward
lead, and that the direction of motion of the arın iture is reversed by changing the
relative directions of current in the armature and field magnet, the brush holder
carrying the brushes will, by reason of the friction between the brushes and
commutator, be automatically caused to move through the arc so as to give the
said brushes a forward lead in the new direction of rotation.
Dated this 24th day of May 1893.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
Improvements in Dynamo Electric Machines.
I, WILLIAM BROOKS SAYERS, of Glenwood, Bearsden, near Glasgow, in the
County of Dumbarton, 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 the Specification of Letters Patent granted to me dated 29 September 1891,
No. 16,572, I have described a construction of dynamo electric machine in which
the commutator strips are connected to the sections of the armature winding through
commutator coils in which an electro-motive force is set up when the machine is
running. the said coils being connected to the armature winding in such a manner
that each coil will have a backward lead with reference to the point between sections
of the armature winding to which it is connected when the machine is running as
a generator, and a forward lead when the machine is running as a motor, and the
commutator brushes being so arranged as to have a backward lead when the
machine is running as a generator and a forward lead when it is running as a
motor, the arrangement in each case being such that the armature current will tend
to increase the total magnetic flux, and that the resultant E.M.F. induced in any
two of the commutator coils and in the section of the armature winding that
connects them, will reverse or tend to reverse the current in the said section of the
armature winding, and reduce to zero, the current in the commutator coil con-
nected to the commutator strip that is about to leave the commutator brush at
the time when one of the said two commutator coils is under that horn of the field
magnet pole which is strengthened by the armature current, and the other has passed
from under the same, and the two corresponding strips of the commutator are
connected by a commutator brush.
Now the present invention has reference to further developments in dynamo
electric machines constructed and operating in the manner referred to, whereby, in
addition to other advantages hereinafter mentioned, such a machine can be run in
either direction, either as a generator or as a motor, without the necessity of
providing it for this purpose with two commutators as described in my said former
Specification.
And in order that my invention may be fully understood I will now describe with
reference to the accompanying illustrative drawings the best way known to me of
carrying it into practical effect.
In the said drawings,
Fig. 1 represents, diagrammatically, the invention applied to a drum armature
winding which is shown as spread out flat or developed so that it the diagram
were cut out and formed into a cylinder it would correctly represent the armature
winding and commutator coils; the said figure also represents the position of the
polar surfaces of the held magnets, the commutator segments, and the commutator
brushes when the machine is running as a generator in the direction of the arrow z.

page_text: Fig. 2 is a similar view to Fig. 1, but with the commutator brushes set for
running in the opposite direction.
Figs. 2 and 2 are further diagrams illustrating the relative arrangement of the
armature sections and cominutator coils.
Fig. 3 is an end elevation illustrating diagrammatically one mode of arranging on
the field magnet, certain polar projections, hereinafter referred to.
Figs. 3, 3 and 3" are diagrams illustrating modified arrangements of such
polar projections.
Fig. 4 is an end elevation showing polar projections on each of the horns of the
field magnets, the arrangement being suitable for a reversible motor.
Fig. 5 is a plan, and Fig. 6 an end elevation, partly in cross section, illustrating
a construction of rocker and brush-holder according to this invention.
Referring to Figures 1 and 2 :-
A A represents the main armature winding, B B the commutator coils, CC the
commutator segments, and D + D- the commutator brushes.
According to the present invention instead of winding the commutator coils B B
around the core of the armature ring or drum, as in the arrangements described in
my said former Specification, I arrange the said commutator coils longitudinally
upon or within the periphery of the armature and so that the longitudinal or side
portions B1 B2 of the convolutions of each of them will, as shown along the middle
portion of Figs and 2, be located on opposite sides of a section or sections of the
armature winding A, and be connected at one end to the main armature conductor.
I find in practice that it is advantageous to arrange each commutator coil so that
its longitudinal or side portions B', 1' will be arranged on opposite sides of two
adjacent sections A'A' of the armature winding A as shown, and to connect one
of its ends to a point A³ of the armature winding that is located between or connects
the said two sections. Each commutator coil may however have its longitudinal or
side portions B¹ B arranged symmetrically at opposite sides of a single section of
the amature winding, provided neither side portion B¹ or B' is nearer to said
section than twice the angular distance between two main armature sections and the
distance apart of such longitudinal or side portions is approximately equal to the
width of each of the recesses formed in the polar horns, as hereinafter described,
or vice versa, the distance apart of the said portions of coils and the width of each
recess being inter-dependent. When there are no such recesses, the distance apart
of the said longitudinal or side portions of the commutator coils is limited by the
condition that if the arrangement is to be reversible, neither of the said portions of
a commutator coil should be nearer to the armature coil to be reversed, than is
shown in the drawings, because if one of thein were nearer, it would necessarily
have to be in the same slot as the armature coil to be reversed at the period when
this coil would be carrying the bulk of the current, and the effective self induction
of the circuits would be much greater when the machine was running in the direction
in which this occurred, than when running in the opposite direction. The best
results, under til circumstances, are obtainable when employing the arrangement
shown, which for this reason is the most advantageous one. The arrangement in
each case is such that as each commutator coil passes under the tip or horn of a
field magnet pole, the portion of the coil which is in front of the said armature
section or sections, will have passed out from under said tip or horn and will
therefore be inoperative, while the portion which is behind the said armature
section or sections, will be under the pole tip, and therefore operative in producing
the resultant E.M.F. required to bring about the reversal, in the manner described
in my said former Specification, of the section A' located between the said point
of connection A³ and the side B' of the commutator coil B that is behind the said
point of connection with reference to the duection of rotation, when the machine
is running as a generator. It will thus be evident that in whichever direction the
machine is running (considering it as a generator) that portion only of the
coil B will be effectively operative that is behind the amature section or
sections relatively to the direction of rotation, and as one side of the coil

page_text: is behind when the machine is running in one direction, and the other side
when the machine is running in the opposite direction, the arrangement becomes
reversible.
When the machine is used as a motor, the foregoing reasoning holds except
that it is the portion of the commutator coil which is in front of the armatur:
sertion or sections, relatively to the direction of rotation, which is operative, and
the portion which is behind which is inoperative, in whichever direction the
machine may be running.
The portions of the main winding A shown dotted are supposed to be directly
beneath the portion shown full, and the two portions B1 B2 of the commutator
coils B are supposed to be lying over the main winding, but these relations are
not essential. The small arrow heads in full and broken lines represent the
direction of the current in the respective portions of the main winding, and the
large arrow heads represent the direction of the current in the commutator coils
which are connected to the commutator segments that are for the time being,
under the brushes. It will be seen that in each case the current in the com-
mutator coils is in the same direction as in the adjacent portions of the main
winding A and that at the instant depicted in the diagram, when a commutator
segment C is midway under each brush, the two portions of the commutator coil
that is, for the time being, active, are symmetrically placed with reference to the
portions of the winding in which the reversal of direction of current takes place.
The commutator coils B may advantageously be each so arranged that the long
side portions of the two armature sections A', A (to a point A³ on the armature
conductor connecting which one end of the commutator coil is connected), will be
located symmetrically between the side portions B', B of the said commutator
coil, so that the said side portions of the latter coil will have an equal lead
relatively to the side portion of that one of the two armature sections concerned
which is nearest to it, and which is about to be reversed, in whichever directiou
the armature may rotate. This will be seen from Figs. 2A and 2B which shew two
sections A¹ A' of a drum armature winding with the corresponding commutator
coil B the two side portions B' B' of which are located on opposite sides of the
said sections, and which are connected at the point A to a part of the drum
winding connecting the said two sections. Fig. 2A shews diagrammatically how
the sections and coil would be arranged if it were not for the space occupied by
the shaft and the crossing of the other wires. The actual arrangement is more
like Fig. 2. In each case if the armature be rotating in the direction of the
arrow x, it is the armature section A¹ which is about to be reversed, the section A²
having just been reversed; while if the armature be rotated in the opposite
direction, it would be the section A2 which would be about to be reversed,
section A having just previously undergone reversal. Thus the necessary con-
dition for complete reversibility is that section A' should be related to the side B¹
of the commutator coil in exactly the same way as section A² is related to the
side B' of the said commutator coil. As will also be seen from these Figures 2A, 2B,
the plane containing the commutator coil is approximately at right angles to those
containing the armature sections A1, A2
In order to make the improved commutater coils B herein before described more
powerfully operative for the purpose
in view,
I sometimes construct the tips or
horns of the field magnet pole pieces (or keepers as they may be called when
there is no winding upon them), with recesses G (Figs. and 4) on the side next
the armature, the width of each recess being made approximately equal to the
distance between the two longitudinal or side portions of each commutator coil.
The magnetic density in the recess will be small compared with that between the
armature and polar surface at each side thereof. The result of this construction,
in the case of a generator, is that the portion of a commutator coil which is in
front of the armature section to which it is connected, and also such armature
section, will be opposite the recess at the time when the portion of the commutator
coil which is behind the said armature section will be still in the part where the

page_text: magnetic density is greatest. An E.M.F. will therefore be induced in the
commutator coil the direction of which (determined by the relative directions of
winding of the main armature coils and the commutator coils) should be such as
to cause the armature current to flow through this commutator coil to the brush.
When the commutator coil reaches the position in which its two sides coincide
approximately with the edges of the said recess G, the E.M.F's induced in the
two sides of the coil will be equal and opposite. When the portion of the
commutator coil which is in front of the said armature section has passed from
the recess and into a position under the pole tip where the magnetic flux is denser,
the portion of the coil which is behind will have passed into a position opposite the
recess and consequently a resultant E.M.F. will now be generated in the coil
opposite in direction to that under the conditions first considered. It will now be
evident that if the commutator brushes D are set so as to correspond with the
position of the recesses, then of the two commutator coils which surround the
sides of an armature section concerned at the moment when two commutator bars
are connected under the brush, that commutator coil which last became con-
nected under the brush, will have a resultant E.M.F. induced in it in such a
direction as to cause the armature current to flow through this commutator coil
to the brush, while the other commutator coil, which, (of the two being considered)
first became connected with the brush, will have a resultant E.M.F. induced in
it tending to stop the current flowing through it from the armature.
The result of these conditions is to bring about the reversal of the armature
section at the ends of which are connected the two commutator coils-during
the time in which the corresponding commutator bars or segments C are passing
under the brush.
In the construction shown in Fig. 3 the recesses G in the pole tips or horns
are each formed by fitting a bi-metallic bridge in between the magnet poles N. S.
The portion of each bridge marked E is of iron and when in position forms an
extension of that pole with which it is in contact and so as to form with such pole
the recess G. The portion of each bridge marked F is of brass or other non-
magnetic material. The two bridges in this example are shown arranged to form
extensions of the upper pole N and the lower pole S when the machine is running
as a generator in the direction of the arrow, and also when running in the contrary
direction as a motor. If it be desired, in either case. to run the machine in the
opposite direction, the two bridges are slid out endways and turned end for end
and replaced, after which the machine may be run in the contrary direction. In
the said Figure 3, the sign + is intended to indicate an advancing current towards
the end of the armature shown, and the sign a receding current. A tunnel
armature is indicated in Figure 3, the two conductors at the bottom or inner
end of the slots belonging to the main armature winding A and those at the top
or outer end, to the commutator coils B. Each recess G is approximately equal
in width to the distance between the two portions of the commutator coil the sides
of which marked B' B respectively lie in slots 1 and 4, and is connected at one
end to a point of the armature winding located between the two main winding
sections which lie in slots 2 and 3.
-
In some cases I may wind insulated wire in the recesses formed in the polar
horns and over the outside of same, and connect up the coils so formed, either in
shunt or series, or in both shunt and series, in order to control the magnetic flux
through the projecting horn or pole extension.
In Fig. 3, H, H represents windings upon the polar extensions E E. These
windings may either form a shunt circuit independently of the shunt coils ou the
field magnets, or they may be connected in series with the latter coils. The
direction of winding is such as to reduce the number of lines of force passing
through these extensions to such an extent as to be only just sufficient to prevent
sparking when the machine is lightly loaded. When the load on the machine is
increased, the armature reaction or cross induction, causes an increase in the
number of such lines of force approximately proportional to the load, the effect of

page_text: which is to tend to obviate the necessity for moving the brushes upon the
cominutator when the load is varied.
In some cases, as when the machine is to be used either as a generator or as a
motor to run always in the same direction, without making any other change than
reversing the relative connection between the armature and field magnet windings,
the bi-metallic bridge may with advantage be arranged as shown in Fig. 34 that
is to say in the opposite direction to that shown in Fig. 3. In this case, if the
polar projection E of the bridge be provided with a winding H as shown, such
winding should be a series one of such direction and number of turns, as will, with
or without the aid of the armature reaction, according to all the requirements
of the design-reduce the total magnetic flux through the said polar projection E
to zero at about haif load, so that a magnetic flux in the opposite direction to that
which would otherwise obtain, will be produced at greater load. By this means,
a nearer approach can be obtained to the desired fixity of position of brushes for
all loads, that is to say to the condition in which the action of the commutator
coils will be proportional to the load.
When the bi-metallic bridge is arranged as in Fig. 34, the coils A' and A' which
have been or are to be reversed are not situated opposite the recess between the
polar projection and the magnetic pole from which it extends but opposite the
recess between the polar projection E and the opposite pole N, and the width of
this latter recess must consequently be equal or approximately so to the width
between the sides B1 B2 of a commutator coil.
Fig. 3 shows a modified arrangement in which the polar projection E is formed
in one with and as a projection from the central portion or thereabouts of the
field magnet N S, whereby the cost of construction is reduced. The magnetic flux
through this polar projection will be approximately proportional to the current in
the armature and will be produced by the armature reaction. With this arrange-
ment the most advantageous action of the commutator coils is secured by winding
the polar projection with a series winding H as shewn in the same manner as that
described with reference to Fig. 3^.
Fig. 3 shews a further modified arrangement in which the bi-metallic bridge of
Figs. 34 and 3B is replaced by a simple polar projection E detachably fixed in a
recess E' in the field magnet pole S by a screw E³. On the opposite pole N is a
groove E similar to the one in which the polar projection is shown fitted so that
the position of the polar projection can be reversed at will when the machine is
required to run in the opposite direction. The recess E¹ that is for the time being
not filled by the polar projection, is filled by a piece of iron to make good the
magnetic circuit.
When the machine is required to run in either direction at will, that is to say,
without its being necessary to do anything more than reverse the direction of
motion, in the case of a motor by reversing the connections of the armature winding
relatively to those of the field magnet winding, recesses G G such as described,
may be formed in all the polar horns, the brushes being set so as to correspond
with those which are for the time being strengthened by the armature current.
Thus in Fig. 4, which illustrates a construction suitable for a reversible motor, if
the armature rotates in the direction of the pair of arrows marked a, then the
recesses G¹ directly opposite to the arrows will be employed, and the commutator
brushes set so as to connect with the commutator segments joined to the commutator
coils whose sides lay opposite the edges of the said recesses.
A reversible motor may however be constructed without any recessed polar
horns or projections, one side only of each commutator coil being operative when
the machine is running in one direction and the other side when the machine is
running the opposite way, as in the construction of dynamo first herein described.
With the arrangement of commutator coils herein described, the effect of the
current in the commutator coils is rather to increase the magnetic flux through the
armature core, whereas in the arrangement described in my said former Specification,
the action of the current in the commutator coils was to cancel part of the

page_text: advantageous magnetising effect of the armature current obtained when the brushes
are set with a backward lead. Furthermore by the arrangement described, the
necessity of carrying the commutator coils over the ends of drum armatures, or
through the centre of ring armatures, is avoided, thereby saving wire and space,
reducing the electrical resistance of the said coils, and enabling the armature to
be constructed in a more practical and neat manner than would otherwise be
Also by the use of the polar projections E or recesses G, practically
the same useful effect, for the purpose specified, can be obtained as if the
commutator coils passed around the armature and were operated upon by both
pole tips.
the case.
Dynamo electric machines of the improved construction herein before described,
when used as motors, may advantageously be provided with brush holders I, as
shown in Figs. 5 and 6, fitted with radial commutator brushes J and carried by a
rocking arm or lever K that is provided with a projection K and is mounted so as
to be free to turn on the armature shaft L through an are limited by adjustable
stops M, the arrangement being such that assuming the armature to have been
running in one direction with the brushes arranged with a forward lead, and that
the direction of motion of the armature is reversed by changing the relative
directions of current in the armature and field magnet, the brush holders I,
carrying the brushes, will, by reason of the friction between the brushes and
cominutator C', be automatically caused to move through an are so as to give the
said brushes a forward lead in the new direction of rotation, as indicated by the
arrows and dotted lines in Fig. 6.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is
1. A dynamo electric machine of the kind herein referred to, in which the
commutator coils are arranged longitudinally upon or within the periphery of the
armature and so that portions of the convolutions of each of them will be located
on opposite sides of a section or sections of the armature winding to a part of
which winding one end of the said commutator coil is connected, the arrangement
being such that as each commutator coil passes under the horn of a field magnet
pole, the portion of the coil which is in front of the said armature section or
sections will have passed out from under the said horn, and will therefore be
inoperative, while the portion which is behind the said armature section or sections
will be under the said horn and therefore operative in producing the resultant
E.M.F. required to bring about the reversal of the armature section that is about
to be commutated, as set forth.
2. A dynamo electric machine of the kind referred to in Claim 1, in which each
of the said commutator coils is also so arranged that the sides of the two sections
of the armature to a point on the connecting conductor of which the said coil is
connected, are located symmetrically between the longitudinal or side portions of
the said coil so that such portions will have an equal lead, relatively to the
armature section which is being reversed, in whichever direction the armature
may run.
3. A dynamo electric machine of the kind referred to in Claim 1 in which the
tips or horns of the field magnet pole pieces or keepers are constructed with
recesses such as G on the side next the armature, the width of each recess being
made approximately equal to the distance between the two longitudinal or side
portions of each commutator coil substantially as herein described for the purpose
specified.
4. A dynamo electric machine in which the recesses G referred to in the
preceding claim are formed partly by polar extensions provided with windings
through which an electric current can be caused to flow for the purpose of con-
trolling the magnetic flux through the said polar extensions substantially as described
for the purpose specified.

page_text: 5. An electric motor of the kind herein referred to, provided with brush holders
adapted to carry radial brushes and mounted so as to be free to move through an
arc limited by adjustable stops so that when the direction of motion of the
armature is reversed, the brush holder will be caused to move automatically by
reason of the friction between the brushes and commutator, into a position to give
the brushes the proper lead in the new direction of rotation substantially as
described.
6. My improved dynamo electric machines constructed arranged and operating as
hereinbefore described with reference respectively to and shewn in Figs 1, 2, 2ª
and 2; and in Fig. 3, or modified according to Fig. 3ª, or to Fig. 3B, or to Fig. 3º
or to Fig. 4 of the accompanying drawings.
7. In an electric motor of the kind herein referred to, the improved brush holder
constructed arranged and operating as hereinbefore described with reference to
and shown in Figs. 5 and 6 of the accompanying drawings.
Dated this huay
uary 1004
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.