IMPROVEMENTS IN ELECTRIC MOTORS APPLICABLE ALSO TO ELECTRIC GENERATORS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by James Alexander Cumine at the
Office of the Commissioners of Patents on the 17th May 1882.
JAMES ALEXANDER CUMINE, of Clerkenwell in the County of Middlesex,
Electrician IMPROVEMENTS IN ELECTRIC MOTORS APPLICABLE ALSO TO ELECTRIC
GENERATORS"
This Invention relates to a novel arrangement of electro magnets in the
construction of an electro motor whereby simplicity and efficiency are obtained the
fixed and revolving portions of the motor are all in the same electric circuit and
there are only two ends of wire forming the circuit through the motor attached to
the commutator the electro magnets are of the bar type but so arranged by being
bolted onto circular discs that two bars form the equivalent of a horse shoe electro
magnet. One of the simplest forms of this motor consists in three pairs of the
electro magnets or three horse shoe electro magnets bolted three onto each side of
a circular disc of iron. They are so arranged that the space between the legs or
limbs of each magnet is equal to the diameter of the end of the limb; the disc,
supporting on each side of itself the electro magnets is open in the centre of its
diameter so that a revolving shaft can pass through, this disc is bolted down to
the main frame of the motor or is otherwise attached thereto; the main frame
carries bearings on each side of the centre disc in which runs a shaft on this shaft
are two discs each disc carries a like number of magnets as are on each side of
the centre disc the ends of the magnets on the revolving discs are in the closest
practical proximity to the ends of the magnets on the fixed disc they are so coupled
up that the magnets facing each other are of opposite and similar polarity
alternately so that when the motor is once started the rotation is kept up without
loss through attraction or repulsion in the wrong direction. Every time the
revolving magnets pass the fixed magnets centres their polarity is changed and
during the change the current is momentarily interrupted in the fixed magnets this
action may be reversed.
The changes and interruption of magnetism are effected by the commutator the
number of magnets employed can be varied but it is preferred to have not less
than six on each disc or side thereof. The dead point in this motor is a mere point
a geometrical point and therefore high economy is attained by making the motor

page_text: double a dead point can be entirely obviated but by means of the method of
constructing my motor even as a single one, the dead point is hardly felt at all, and
then, only when the motor happens to stop on it.
The motor may be constructed with only one revolving disc-and with magnets
on one face, and the fixed disc with magnets on one face only but it is preferable
to have magnets on each side of the fixed disc and two revolving discs with
magnets to correspond-the motor under these circumstances is better balanced
than if made singly; in the latter case there is not the strain on the frame that
there would be if there was only one revolving disc and magnets.
The magnets can be coupled either in one single series or in quantity two, more
or less may be so coupled.
The electro magnets which are of constant polarity may be made either horse-
shoe or bar.
The construction of the motor may be modified in several ways still employing
the arrangements whereby the poles are produced as above described.
The disc form of the motor may be modified in construction so as to be used as a
dynamo machine in which case the centre disc and its indicating magnets would
revolve and the end discs would be stationary the magnets on the end discs are so
arranged that one, say the upper half is of one polarity the lower half of opposite
polarity for instance if there are twelve projecting magnet limbs, six adjoining are
of one polarity, the other six of the opposite polarity-the revolving disc may
carry any desired number of projecting magnet limbs coupled and connected to a
collector in the same manner as are the coils on the bobbin of the machine known
as the continuous current "Gramme."
The arrangement of fixed magnets described is applicable to any dynamo of the
continuous core type.