IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES."
Year: 1882

page_text: LETTERS PATENT to William Hopkin Akester, Electrician, and Thomas
Beckett Barnes, Engineer, both of Glasgow, in the county of Lanark, North
Britain, for an invention of IMPROVEMENTS IN DYNAMO ELECTRIC
MACHINES."
"
PROVISIONAL SPECIFICATION left by the said William Hopkin Akester
and Thomas Beckett Barnes at the Office of the Commissioners of Patents
on the 1st March 1882.
WILLIAM HOPKIN AKESTER, Electrician, and THOMAS BECKETT BARNES, Engineer,
both of Glasgow, in the County of Lanark, North Britain, "IMPROVEMENTS IN
DYNAMO-ELECTRIC MACHINES
"
This Invention has for its object to increase the efficiency of dynamo-electric
machines and to diminish the cost of their construction.
In machines made with the improvements the stationary parts comprising the
field magnets with their exciting electric coils and the pole pieces may be arranged
as in some existing machines, the present Invention dealing principally with the
rotating parts or armatures and the commutators. In one modification there are
two compound rotating armatures on one horizontal shaft; and there are two field
magnets which are bars parallel to and on opposite sides of the shaft and which
have pole pieces at their ends, the northward and southward pole pieces of one
field magnet being arranged to face the southward and northward pole pieces of
the other field magnet. One of the compound armatures is between each pair of
pole pieces the inner faces of which are made cylindrically concave so as to encircle
the armatures.
Each armature consists of a series of wheels made of malleable castiron and fixed
on central busbes of brass or other nonmagnetic material fixed on the shaft. Each
wheel has a centre part and a cylindrical rim and these are connected by hollow
tubes or cylindrical cases in the positions of spokes. When complete a radial iron
or steel spindle occupies the centre of each case being held by its inner end being
screwed to the centre part of the wheel, whilst its outer end has a head formed on
DC31

page_text: it which closes the case and externally forms a continuation of the rim of the
wheel. An insulated wire is coiled round each spindle; and it is an advantage of
the construction that the coiling can be easily effected before the spindles are fixed
in their cases.
One or more slots are formed in the sides of each case to prevent
unsuitable currents or actions being induced in the cases by the electric currents
passing through the coils on the spindles. The ends of the wires of the coils are
led in and out through the slots in the cases and are connected to the commutator
strips. The several wheels composing each armature are combined together so
that the radial cases of the several wheels form helical series, the amount of helical
twist through the set of wheels being as measured circularly about equal to the
space between two cases on one wheel. In this way continuity and uniformity of
action are secured as the ends of the small electro magnets constituted by the radial
spindles with their coils, pass the various parts of the stationary pole pieces in
regular rotation, the last one of each helical series being followed by the first one
of the next without interval.
In the improved commutator, the metal strips are arranged helically with the
view of rendering the action more continuous and uniform. The spring blades or
brushes by which the currents generated in the armatures are transmitted to the
circuit conductors, are secured in holders which are set in an insulated manner on
spindles carried at diametrically opposite points of a ring which encircles the
commutator. This brush ring as it may be termed is held in a clip ring formed
with a foot by which it is fixed to the bed frame of the machine. The clip ring is
cut through at its top and the parts are drawn together by a screw, which is
slackened to allow the brush ring to be adjusted and tightened to fix it.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Hopkin Akester and Thomas Beckett Barnes in the
Great Seal Patent Office on the 30th August 1882.
WILLIAM HOPKIN AKESTER, Electrician, and THOMAS BECKETT BARNES, Engineer,
both of Glasgow, in the County of Lanark, North Britain, "IMPROVEMENTS IN
DYNAMO-ELECTRIC MACHINES."
Our said Invention has for its object to increase the efficiency of dynamo-electric
machines and to diminish the cost of their construction.
In machines made with our improvements the stationary parts comprising the
field magnets with their exciting electric coils and the pole pieces may be arranged
as in some existing machines the present Invention dealing principally with the
rotating parts or armatures and the commutators. In one modification there are
two compound rotating armatures on one horizontal shaft, each consisting of a
series of wheels or partial wheels made of malleable cast iron and fixed on central
bushes of brass or other non-magnetic material fixed on the shaft. Each wheel is
made with a series of hollow tubes or cylindrical cases in the positions of spokes
and all in one plane at right angles to the shaft. When complete a radial iron or
steel spindle occupies the centre of each case being held by its inner end being
screwed to the centre part of the wheel, whilst its outer part has a head
formed on it which closes the case and externally forms a continuation of the
periphery of the wheel. An insulated copper wire is coiled round each spindle;
and it is an important advantage of the construction that the coiling can be
easily effected before the spindles are fixed in their cases. One or more slots
are formed in the sides of each case to prevent unsuitable currents or actions being
induced in the cases by the electric currents passing through the coils on the
spindles. The several wheels composing each armature are combined together so
that the radial cases of the several wheels form helical series, the amount of helical
twist through the set of wheels being as measured circularly about equal to the
space between two cases on one wheel. In this way continuity and uniformity of
action are secured, as the ends of the small electro or induced magnets constituted
by the radial spindles, pass the various parts of the stationary pole pieces in
regular rotation, the last one of each helical series being followed by the first one
of the next without interval. In our improved commutator the metal strips are
arranged helically with the view of rendering the action more continuous and
uniform; and the spring blades or brushes by which the currents are collected and
transmitted to the circuit conductors are secured in holders carried in an improved
manner hereinafter described.
And in order that our said Invention and the manner of performing the same
may be properly understood we hereunto append two sheets of explanatory drawings
to be hereinafter referred to and representing our improved apparatus.
Figures 1, and 2, on sheet, 1, of the accompanying drawings are a plan and a
sectional side elevation of a dynamo-electric machine made according to one
modification of our Invention, Figure, 3, on sheet, 2, is a sectional end elevation
and figure, 4, is a transverse vertical section showing the commutator and collecting
brush details. Figure, 5, is a section showing a modified construction of the
arinature; and figure, 6, shows a modified construction of the armature and
arrangement of the field magnets. In these drawings the same reference
numerals are used to mark the same or like parts wherever they are repeated.
In the machine shown in figures 1 to 4, the main horizontal shaft, 10, is carried
by three bearing blocks, 11, bolted to a bed frame, 12, and has on it in one of the
spaces between the bearings fast and loose pulleys, 13, for a driving belt. In the

page_text: other space between the bearings, 11, the shaft, 10, has fixed on it two compound
armatures and between them commutator bosses, 14. There are two parallel
horizontal field or stationary magnet bars, 15, one on each side of the shaft,
and these bars excepting at their extreme ends are covered with exciting coils, 16,
of insulated copper wire. There are four pole pieces, 17, one attached to each end
of each magnet bar, 15, and the magnetization is arranged so that the northward
and southward poles of one field magnet have facing them the southward and
northward poles respectively of the other field magnet. The pole pieces, 17, are
made with cylindrical concavities on their inner faces such concavities being con-
centric with the shaft, 10, and the peripheral parts of the rotating armatures move
nearly in contact with the concave surfaces.
Each compound rotating armature consists of a number of wheel-like sections or
pieces fixed on a brass boss, 18, keyed on the shaft, 10. Each wheel piece, 19
which is by preference made of malleable castiron, consists of a number of
cylindrical cases or tubes, 19, formed radially or in the positions of spokes upon a
centre which fits on the brass boss, 18. In each spoke-like or radial case, 19, there
is centrally placed a radial spindle, 21, of soft iron on which there has been wound
a coil, 22, of insulated copper wire, the spindle, 21, being fixed by screwing its
inner end into the centre part of the wheel piece, whilst a head formed on the
outer end of the spindle closes the outer end of the case fitting into a check or
rebate formed for it in the case and having its outer surface flush with a flange
formed on the other end of the case. Each case, 19, is formed with a slot, 23,
which is made large enough at the inner end or other suitable part for the passage
of the two ends of the coil, 22, which ends are led thence to the commutator
boss, 14. To avoid confusion the numerous wires between the coils, 22, and the
commutator boss, 14, are not shown in the drawings; but it may be mentioned
that those of wheel pieces further from the commutator boss, are passed through
between the cases, 19, of the nearer wheel pieces. The several wheel pieces of each
rotating armature are placed on the shaft so that the cases, 19, are arranged in
helical series as shown in figure, 2, for the purpose herein before explained. The
wires of the several coils, 22, may be connected in various ways; but where con-
tinuous currents of relatively moderate intensity are desired we prefer to connect
the several coils of each helical series end to end in order as if portions of one
continuous coil and to connect the opposite end wires of the two outer coils of
each helical series to successive metal strips on the commutator boss, the inner end
wire of one helical series being connected to the same metal commutator strip as
the outer end wire of the next helical series.
In figures 1 and 2, three pairs of brushes, 24, or sets of spring plates or metal
strips are shown, allowing of the electricity generated being collected in three
separate currents, one corresponding to the whole of one compound rotating
armature and the other two each to about half of the other rotating armature.
One of the smaller currents is intended to be used in ordinary cases for exciting
the field magnets, the brushes which collect it being connected in the ordinary
way to the coils, 16. The several brushes, 24 are secured in holders, 25, which
are carried in an insulated manner on two spindles, 20, fixed at diametrically
opposite parts of a ring, 27, which encircles the shaft, 10, between the commutator
bosses, 14; and this brush ring, 27, as it may be termed is held in a clip ring, 28,
formed with a foot by which it is fixed to the bed frame, 12. The clip ring, 28,
is cut through at its top and the parts are drawn together by a screw, 29, which
is slackened to allow the brush ring to be adjusted and tightened to fix it. Each
pair of brush holders, 25, is connected by links, 30, to a hand lever, 31, to which a
spring, 32, is applied in a manner to press the brushes against the commutator.
By depressing one end of the lever, 31, the brushes are turned off the commutator,
and the lever may be held down by a catch when it is wished to keep the parts
disconnected.
In the modification of armature shown in figure, 5, the boss, 18, is made of iron,
and brass belts or zones, 33, are inserted at the middles of the tubes or cases, 19, the

page_text: object being to interpose a non-magnetic material between the outer and inner
ends of the cases, 19. The outer ends of the cases, 19, are cut quite separate from
the inner ends but are held in their places by the radial spindles, 21.
In the modification shown in figure, 6, whilst the cases, 19, are retained of the
same size as in the other figures, the external diameter of the wheel piece is
doubled, this allowing of considerably more than double the number of cases, 19,
whilst half the number of revolutions of the shaft will give the same speed at the
periphery To properly take advantage of this increased number of cases, 19, with
their several coils and iron cores or spindles, the number of field or stationary
magnets is increased, and the pole pieces, 17, are arranged equidistantly round the
armatures but so as to be alternately northward and southward. The wires of the
coils may be connected in such a way as to combine all which are at each moment
similarly acted upon, or they may be connected or coupled in any other suitable
manner.
Having thus particularly described our said Invention and the manner of per-
forming the same we have to state that we do not restrict ourselves to the precise
details herein described or delineated but that what we believe to be novel and
original and claim as the Invention secured to us by and in terms of the herein.
before in part recited Letters Patent is :-
1. The combination of parts hereinbefore described and constituting the improved
dynamo-electric machine.
2. The improved rotating armature consisting of one or more wheel pieces each
having a number of radial spindles enclosed in coils of insulated copper wire the
said coils being enclosed in cases which are entirely of iron or have iron ends with
middle parts of brass or other suitable non-magnetic material and the various
parts being arranged and operating substantially as hereinbefore described.
3. The modified form of armature wheel piece combined with one or more pairs
of field-magnet pole pieces hereinbefore described with reference to figure, 6, of the
accompanying drawings
In Witness whereof I, William Hopkin Akester on behalf of myself
and of the said Thomas Beckett Barnes have hereunto set my hand
and seal this twenty-eighth day of August in the year of our Lord One
thousand eight hundred and eighty-two.
Witness
EDMUND HUNT
Patent Agent
Glasgow
W. H. AKESTER. (L.S.)