IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES
Year: 1882

page_text: .LETTERS PATENT to Alfred James Jarman of 10 Glenarm Road Hackney
London E for an invention of IMPROVEMENTS IN DYNAMO ELECTRIC
MACHINES
PROVISIONAL SPECIFICATION left by the said Alfred James Jarman at
the Office of the Commissioners of Patents on the 5th June 1882.
ALFRED JAMES JARMAN of 10 Glenarm Road Hackney London E. IMPROVE
MENTS IN DYNAMO ELECTRIC MACHINES
My Improvements consist in so forming the pole caps, or inducing pieces, of the
Field Magnets of Dynamo machines, or the pole caps of the inducing magnets of
Magneto Electric Machines, as to be adjustable with regard to each other, and to
the armature revolving within such pole caps, or inducing pieces. In Dynamo
Electric, or Dynamo Magneto Electric Machines, as at present made it is not
possible to augment, or diminish the current obtainable, unless resistance such as
coils of German silver wire, or Iron wire or some similar method for obstructing
the flow of the current be used; much engine power is thus wasted, and a con-
siderable heat induced in such resistance coils, which is also a waste of power; My
object is to enactly obtain the required current, by causing the poles of my field or
inducing magnets, to approach or recede from the armature, The Magnetic effect
being susceptable of considerable variation, within a small range; and as is well
known a standing difficulty in the construction of Dynamo Machines, consists in
making the armature run sufficiently close to such pole or inducing pieces, as to
obtain the full effect which difficulty is quite overcome by my method of adjust-
ment. I can adjust my poles by means of set-screws-the caps being made to
slide upon or through the magnet poles; or the legs of the magnets can be hinged
or in machines of The Siemens type, each half of the Field Magnets may be
-separated by set screws or wedges; operated by suitable means or the side plates
of machines of the usual type, may be made to slide upon or within each other.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alfred James Jarman in the Great Seal Patent Office on the
2nd November 1882.
ALFRED JAMES JARMAN of 10 Glenarm Road Hackney London. E.
MENTS IN DYNAMO ELECTRIC MACHINES
IMPROVE
My improvements consist in so forming the pole caps or inducing pieces of the
field magnets of dynamo electric machines, or the pole caps of the inducing
magnets of magneto electric machines, under which title are also included what
are known as electromotors, as to be adjustable with regard to each other and
to the armature revolving within, such pole caps or inducing pieces. In dynamo
electric, or magneto electric machines, as at present made, it is not possible to
augment or diminish the current obtainable, unless resistance consisting of coils
of german silver, or iron wire or some similar substance capable of obstructing
the free flow of the current be used, much engine power is thus wasted, and a
considerable heat induced in these resistance coils, which in itself constitutes a
futher waste of power. My invention enables me to obtain exactly the current
needfull for my purpose, within the current producing power of the machine, so
that the expenditure of power is proportional to the work effected, whether it
be as light, heat, or power. As is well known to Electricians, the inductive effect
of a magnet, whether of the class known as as permanent.or existing as an electro-
magnet varies as the square of the distance of the inducing poles from the
armature. It is obvious therefore that within very narrow limits, I can largely
augment or decrease the current derivable from my armature, by causing the poles,
or pole pieces or caps to approach or recede from such armature and each other.
It is also well known, that owing to the poles of magnets used in dynamo electric
or magneto electric machines being immoveable, and rigid, the highest power
derivable from such machines cannot be obtained, as allowance must be made for
"spring" in the spindle carrying the armature or the expansion of the wire, of
which it is composed, which is due to centrifugal force. My invention however,
enables me to overcome this difficulty, since I am able to adjust the pole caps or
pieces, after the spindle, and armature have taken up their working bearings.
I adjust my pole caps or pieces in a variety of ways, to suit the particular machine
it is intended to regulate, in this manner. The caps or poles can be made to
approach or recede from each other or the armature, by means of a right and left
hand thread, passing through such caps, or the caps can be regulated by means of
set screws, the poles sliding upon, or within the magnets of which they form part,
or the legs of the magnets, in machines of the Edison type, can be hinged, or
pivoted, and the pole caps adjusted by set screws, or screws and wedges, or the
side frames, carrying the field magnets can be made to slide upon, or within
each other.
Having now generally described my invention, I will proceed to explain the
manner, in which I apply the same by means of the accompanying drawings.
Fig 1 & 2 Shew section and end view of the pole pieces of a dynamo machine of
ordinary type A A¹ are the caps sliding in this case within the pole pieces as
shewn at B B' the lower side of the caps are tapped to receive a right and left
hand thread screw C, while the upper side carries four guide pins D to impart
rigidity, to the pole caps, when forced outwards, or inwards, by the screw, the nuts
can be made in halves if more convenient or the pole caps can be forced in or out
as shewn at D Fig 8
Fig 3 & 4 Shew a method of adjusting the poles suited to that type of machine

page_text: known as Siemen's, by means of the right and left hand thread at C. Fig 9 its
application to Edison type of machine
Fig 5 & 6 Shew in section, and front elevation, a method of application suited to
machines of the gramme type, in this case the pole pieces are hinged and are
regulated by the thumb screws at A¹ A".
Fig 7 shews the method I employ with this class of machine when it is
convenient to raise the magnets themselves in this case the bars shewn at B. B¹.
fig 6 are seated in bearings E¹ E" fig 7 which are forced apart by the right and
left hand screw at F the bearings being free to slide in the groves G G
Fig 8 Shews another method of regulating dynamo machines of ordinary type by
means of a simple set screw inserted in the back of the field magnets. Having
now described my invention by the aid of the drawing and thereby shewn, several
methods by which it can be applied to the various types, of machine in general use
I should wish it under-stood that I do not confine myself to the particular design
or methods shewn and described, as suitable to the types of machines shewn, as it
is quite possible to accomplish the end I have in view in other ways than those
shewn, and described, without departing from the main feature or principle of my
invention.
I claim as under
1st The regulation of the current derivable from dynamo electric or magneto
electric machines by causing the pole caps or pieces to advance or recede from each
other and from the armature which they enclose whether used for producing heat,
light power or any purpose to which such machines are usually put
2nd The adjustment of such pole caps by means of screws having right and left
hand or single threads the adjustment of such pole caps or pieces by set screws,
wedges, bolts and nuts, hinges or by causing the main frames to slide upon or
within each other.
3rd The application of such adjustment as shewn and described to the
regulation of what are known as electromotors or engines whether magnetic or
electro magnetic
In witness whereof I the said Alfred James Jarman have hereunto set my
hand and seal this 25th day of October in the year of our Lord 1882
Witness
FRANCIS M ROGERS
21 Finsbury Pavt. EC.
ALFRED, JAMES, JARMAN. (L.S.)