IMPROVEMENTS IN MACHINES FOR PRODUCING ELECTRIC CURRENTS."
Year: 1882

page_text: LETTERS PATENT to James Brockie, of 6, Saltoun Road, Brixton, in the
County of Surrey, for an Invention of "IMPROVEMENTS IN MACHINES FOR
PRODUCING ELECTRIC CURRENTS."
PROVISIONAL SPECIFICATION left by the said James Brockie at the Office
of the Commissioners of Patents on the 10th February 1882.
JAMES BROCKIE of 6 Saltoun Road Brixton in the County of Surrey.
"IMPROVEMENTS IN MACHINES FOR PRODUCING ELECTRIC CURRENTS.' "
According to my improvements the revolving armature consists of two complete
iron rings mounted on a common shaft, but magnetically insulated from it by
means of a brass or other non-magnetic boss these two iron rings are placed at a
short distance apart say for example eight or nine inches and may in that case be
sixteen inches in extreme diameter. Now between these two rings I arrange bars
of soft iron at convenient distances apart, which are well secured to the said two
rings. Coils of wire are wound at the two extremities of each of the said bars,
the size and length of the coils of course depending upon the nature of the current
required, but in any case the two ends of the respective coils or groups of coils are
led to suitable contact pieces placed round the shaft carrying the armature, so that
the currents induced in the said coils may be collected by suitable rubbers, and
given off to an external circuit, as in nearly all machines of this class. The field
or exciting magnets have four poles, arranged two on either side of the revolving
armature, and opposite each other, vis: a north and a south pole, but the north ou
one side is opposite the south on the other side, so that the two rings shall be of
opposite polarity in any given line through the length of the transverse bars.
Now it will be seen that if this armature be revolved within this magnetic field,
currents of electricity will be produced in the coils around the transverse bars,
whose intensity will of course depend upon the rapidity of the motion and intensity
of the field. It will be observed that the field magnets or rather their pole pieces
may be placed exceedingly close to the faces of the two revolving rings, as the

page_text: latter may be turned quite true, and no projecting coils of wire to be avoided, thus
a comparatively weak magnetic field will exert a powerful inductive influence on
the revolving armature. I have said the coils of wire are placed at the two ends
of the transverse bars, but of course they may be wound the entire length, however
as most of the inductive effect takes place near the poles of a magnet I prefer to
leave the middle part unwound. I sometimes however utilize this part of the bar
magnets for the production of currents to excite the field magnets of the machine,
by winding this middle part with separate coils, the currents of which are collected
by separate brushes or rubbers and led round the circuit of the field magnets. By
constructing machines according to this plan the winding of the armature becomes
very simple as the cross bars or magnets are constructed to lift out from between
the two iron rings, being held in place by suitable screws, so that the coils may be
wound on a lathe and slipped on the ends of the bars, also should damage be done
to any particular coil, the repair can be readily effected. It will also be seen that
this construction of machine readily lends itself to various groupings of the coils
either for quantity or tension currents without altering the gauge or length of wire
employed. I have spoken of bars of soft iron being placed between the two iron
rings but I sometimes use bundles of small iron wire instead or thin sheets of iron;
in the two iron rings likewise I sometimes cut a deep groove and fill this groove
with soft iron wire.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Brockie in the Great Seal Patent Office on the
16th August 1882.
JAMES BROCKIE of 6 Saltoun Road, Brixton in the County of Surrey.
"IMPROVEMENTS IN MACHINES FOR PRODUCING ELECTRIC CURRENTS."
This Invention relates to the construction of the revolving armature (which is
the essential feature in all machines for the production of currents of electricity).
According to my improvements the revolving armature consists of two complete
iron rings mounted on a common shaft, but magnetically insulated from it by
means of a brass or other non-magnetic boss, these two iron rings are placed at a
short distance apart say for example eight or nine inches and may in that case be
sixteen inches in extreme diameter. Now between these two rings I arrange bars
of soft iron at convenient distances apart which are well secured to the said two
rings. Coils of wire are wound at the two extremities of each of the said bars, the
size and length of the coils of course depending upon the nature of the current
required, but in any case the two ends of the respective coils or groups of coils are
led to suitable contact pieces placed round the shaft carrying the armature so that
the currents induced in the said coils may be collected by suitable rubbers and
given off to an external circuit as in nearly all machines of this class. The field or
exciting magnets have four poles arranged two on either side of the revolving
arinature and opposite each other viz. a north and south pole but the north on one
side is opposite the south on the other side, so that the two rings shall be of
opposite polarity in any given line through the length of the transverse bars. Now
it will be seen that if this armature be revolved within this magnetic field, currents
of electricity will be produced in the coils around the transverse bars whose
intensity will of course depend upon the rapidity of the motion and intensity of
the field. It will be observed that the field magnets or rather their pole pieces
may be placed exceedingly close to the faces of the two revolving rings, as the latter
may be turned quite true and no projecting coils of wire are to be avoided; thus a
comparatively weak magnetic field will exert a powerful inductive influence on the
revolving armature. I have said the coils of wire are placed at the two ends of
the transverse bars but of course they may be wound the entire length; however
as most of the inductive effect takes place near the poles of a magnet 1 leave the
middle part unwound; I sometimes however utilize this part of the bar magnets
for the production of currents to excite the field magnets of the machine, by
winding this middle part with separate coils, the currents of which are collected
by separate brushes or rubbers and led round the circuit of the field magnets. By
constructing machines according to this plan the winding of the armature becomes
very simple as the cross bars or magnets are constructed to lift out from between
the two iron rings, being held in place by suitable screws, so that the coils may be
wound on a lathe and slipped on the ends of the bars; also should damage be done
to any particular coil, the repair can be readily effected.
It will also he seen that this construction of machine readily lends itself to
various groupings of the coils either for quantity or tension currents-without.
altering the gauge or length of wire employed. I have spoken of bars of soft iron
being placed between the two iron rings but I construct these bars in pieces which
are united forming compound bars; I may thus use bundles of small iron wire or
thin sheets of iron or small pieces of iron or iron filings enclosed in cases; in the

page_text: two iron rings likewise I sometimes cut a deep groove and fill this groove with soft
iron wire.
Figure 1 shews in perspective the improved revolving armature and consists of
the main shaft A upon which the non-magnetic boss B is keyed-carrying the
two iron rings C and D. The cross bars or magnets E E E are shown occupying
the space between these iron rings and to which they are securely fastened; the
coils F F F are wound on the extremities of the transverse bars, and the ends of
the respective coils are led to the contact pieces G G forming the commutator; the
shaft is preferably made hollow at the larger end as shown and the wires are led
through the slots HHH into the interior of the shaft whence they emerge by the
other slots H2 H2 and then to the contact pieces. The joining up of the several
coils may be done in various ways. 1st The free ends of each pair of coils may be
led to contact segments on exactly opposite sides of the commutator, in this case
twice as many contact pieces as there are cross bars or magnets are required, and
the currents in each coil are commutated separately, and they will be cut out of
circuit during the revolution of the armature except at those times when the
rubbers or brushes make contact with the particular segments belonging to the
coils. 2nd Two or more cross magnets could be joined up in series or in parallel
circuit and the two free ends of this system led to contact pieces on opposite sides
of the commutator 3rd The coils may be joined continuously, forming a complete
circuit and in this case any convenient number of wires may be arranged at equal
distances making electrical contact with this circuit and led to each segment of the
commutator in regular order. 4th The coils may be joined up in pairs diame-
trically opposite each other. Figures 2 and 3 show a complete machine constructed
with the aforesaid armature. The pole pieces N N and SS of the field or exciting
magnets are bolted to brass or non-magnetic blocks P P P P-which latter are in
turn bolted to the foundation plate W. The faces of the pole pieces are accurately
planed or turned and the revolving armature is also turned on the outside iron
faces so that a very small space intervenes between the field magnets M and the
armature; rings R R R are turned on the shaft at the driving end Fig 1 and
work in a thrust block bearing to prevent end play.
As before stated I sometimes wind the middle part of the cross bar magnets
EE E and use the current so produced to excite the field magnets, in which case
an additional commutator is required. I construct the bar magnet in layers as
shown in plan at Figure 4 and in side view at Figure 5 where two side plates K K
are rivetted to the end blocks L L and so form a space which is filled up with
several sheets of iron all rivetted together as shown or filled with iron wire, or iron
filings as shown in Fig. 2 in which latter case a covering will be required to keep
the filings in position. The iron rings C D are sometimes made with a deep groove
cut in their peripheries and these grooves are then filled up with soft iron wire or
hoop iron for the purpose of reducing the tendency to heat and obtaining a better
magnetic effect.
I declare that I claim :-
First: In machines for producing electric currents the construction of the
revolving armature having two iron rings CD mounted on a non-magnetic boss B and
transverse compound iron bars E fixed between the said two rings and upon which
bars E coils of insulated wire F are wound, the said armature being made to revolve
between the poles of field magnets whose polarity is arranged so that the two
iron rings CD shall be of opposite polarity in any given line through the length of
the cross bars or magnets substantially as described and as shown on the accom-
panying Drawing.
Second: Constructing the bar magnets of such revolving armatures of several
separate pieces or sheets of iron fastened together, or bundles of iron wire or hollow
iron cases filled with iron pieces or filings, the said compound bars being wound
with insulated wire substantially as described and as shown.
Third: In armatures constructed as described winding the iron compound bars

page_text: of the same at each end for the production of the outside current of the machine
and also if desired winding the middle parts of said bars with a separate coil the
current from which is used to excite the field magnet of the machine substantially
as set forth.
In witness whereof I the said James Brockie have hereunto set my hand
and seal this Fifteenth day of August in the year of our Lord One thousand
eight hundred and eighty two.
JAMES BROCKIE. (L.S.)