IMPROVEMENTS IN DISC DYNAMO
Year: 1882

page_text: LETTERS PATENT to John Gordon of 9 New Broad Street, London, in the
county of Middlesex, and John Gray of 9 New Broad Street, London, in the
county of Middlesex for an Invention of "IMPROVEMENTS IN DISC DYNAMO
PROVISIONAL SPECIFICATION left by the said John Gordon and John Gray
at the Office of the Commissioners of Patents on the 4th October 1882.
JOHN GORDON, and JOHN GRAY IMPROVEMENTS IN DISC DYNAMO AND MAGNETO
ELECTRIC MACHINES AND ELECTRO-MOTORS
Two discs rotate on parallel axes with their peripheries pressed in contact by
springs or otherwise so that the one may drive the other after the manner of friction
wheels. These discs consist of thin sheets of brass, copper, or any other good
conductor of electricity;. this thin web of the disc is surrounded by a ring or flange
to form a broad surface of contact when the two discs are pressed together. The
discs are divided by radial cuts running from the circumference to within a few
inches of the centre, into a considerable number of sections. A magnet is placed
over the discs so that its pole pieces shall cover two sections at least of each disc
lying about the line of centres. The magnet may be an electro or permanent
magnet; but an electro-magnet is preferable. The current in the rotating discs or
armature passes from the axis of one disc, through the point of contact of the two
discs to the other disc. The magnet coils are connected up in shunt circuit to the
bearings. The main external circuit is also connected to the bearings. If it should
be inconvenient to use the bearings for drawing off the current, the shaft may be
made to project from each end and brushes applied to them. Three or more discs
may be used running in frictional contact, with a magnet between each pair of
axes as already described. The first and last axes are the terminals of the armature.
Each radial section of the disc is insulated from the others except at the central
boss. The discs are to be made as thin as possible, and to run as close to the pole
pieces of the magnet as possible. One disc is driven from the prime mover and
the other receives its motion from it by the frictional contact of their peripheries:
or both may be driven at the same speed in opposite directions.
The machine may be used for a motor by passing an electric current into it.
If a higher electromotive force is required flat, insulated coils of wire laid on the
discs may be used instead of the radial sections.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Gordon and John Gray in the Great Seal Patent Office on
the 3rd March 1883.
JOHN GORDON of 9 New Broad Street in the county of Middlesex, and Joun
GRAY of 9 New Broad Street in-the county of Middlesex, IMPROVEMENTS IN
DISC DYNAMO AND MAGNETO ELECTRIC MACHINES AND ELECTROMOTORS.
Two discs rotate on parallel axes with their peripheries pressed in contact by
springs or otherwise, so that the one may drive the other after the manner of friction
wheels. These discs consist of thin sheets of brass, copper, or any other good
conductor of electricity. This thin web of the disc is surrounded by a ring or flange
to form a broad surface of contact when the two discs are pressed together. The
discs are divided by radial cuts running from the circumference to within a few
inches of the centro, into a large number of sections. A magnet is placed over the
discs so that its pole pieces shall cover two sections of each disc lying about the line
of centres. The inagnet may be an electro- or permanent inagnet; but an electro-
magnet is preferable. The current in the rotating discs or arianture passes from the
axis of one disc through the point of contact of the two discs to the other disc.
The magnet coils are connected up in shunt circuit to the bearings. The main
external circuit is also connected. to the bearings. If it should be inconvenient to
use the bearings for drawing off the current, the shafts may be made to project
from each end, and brushes applied to them. Three or inore discs may be used
'running in frictional contact with a magnot between each pair of axes as already
described. The first and last axes are the terminals of the armature. Each radinl
section of the disc is insulated from the others except at the central boss. The disc
is made as thin as possible, and to run as close to the pole pieces of the magnet as
possible. In order to strengthen the discs, after they are cut into sections, solid
brass rings are forced under the flanges on each side, so as to put the sections of
the web in tension. These solid rings are turned conical on the outer periphery,
and are insulated from the flanges by strips of wood or other suitable insulating
inaterial. They are squeezed under the flanges by bolts passing right through both
rings, and insulated by tubes of paper from the web of the disc.
Another mode of constructing the discs is shown in the Drawings annexed to
the Specification. The 'discs or wheels in this case are made like bicyclo' wheels,
that is to say the tire is connected to the boss by copper wires in tension. In
Fig. 1. is seen an olevation of the discs and in Fig. 2. a plan. Fig 3. is a section
of the tire, C. is the section of the hollow brass ring. Inside this ring is placed a
sheet of thin india-rubber or any other suitable insulating material, B, and above
the insulating material are placed short pieces of brass A connected to the end of
cach wire spoke D, and insulated from each other. The arrangement of these
brass sections is shown in Fig 2. The line dividing each pair may be made
slightly diagonal in opposite directions in each disc so as to make the two discs or
wheels run more smoothly together. Fig 4. shows the boss of the disc; the wire
spokes A A.A A are shewn screwed into the boss, but they may be connected in
other convenient ways. E E Figs 1. and 2. is the base plate of cast iron, in which
are fixed the shanks of the magnets C.C. DD are the polo pieces of the magnets.
These polo pieces are placed as close to the spokes of the discs as possible without
interfering with the rotation of the discs, a square notch being cut in each pole
piece to make room for the tires of the discs. One of the discs A runs in fixed
bearings as shown, the bearings of the other are supported on the end of a bell
crank lover F F, on the other end of which is placed a weight G, by which means

page_text: one disc is pressed in contact with the other. Springs or any other suitable means
may be used for this purpose. The insulated copper wire is wound on the
shanks CC of the electro magnet, so as to make one of the pole pieces D a south
pole, and the other a north pole. The wire spokes are shewn with a slight spread
at the boss to give the discs the necessary strength, but this should be as small as
possible.
Fig. 5 shews an arrangement with three discs, A, B, C, and two magnets D and E.
Any number may be combined in this way. Fig. 6. shews another arrangement.
In this case if F is a south pole of a magnet E and G must be north poles: A and D
which must be insulated from each other would then bo the two terminals of the
annature. To get higher electromotive force than from the discs as described, flat
coils may be substituted for the sections of the discs; an end of each coil will be
attached to the brass piece on the tire, and the other end to the boss. These flat
coils may be fixed on thin discs of wood, papier maché or other suitable material.
For continuous currents the sections on the periphery must be so arranged that
contact is made when one side of the coil only is passing between the poles of the
magnet. If the sections were otherwise arranged alternating currents would be
obtained. Instead of the rolling contact described, the discs may be connected by
a fixed copper brush; brushes may also be placed at the outer edges of the discs,
and by putting two additional magnets in a line with that shewn in the drawing,
the current will then pass right across the whole diameters of the two discs.
Having now described and particularly ascertained the nature of our said
Invention, and the manner in which the same is to be practically constructed, we
would observe in conclusion, that what we consider to be novel and original and
therefore claim as the Invention secured to us by the hereinbefore in part recited
Letters Patent is:
First Thin discs of good electric conducting material rotating between the
poles of a magnet, and divided into or built in radial sections, and rolling in contact
or connected by brushes substantially as herein before described with reference to
the accompanying drawings, for generating electric currents as described, or to act
as motors when electric currents are passed into them.
Second. The fixed coils fixed upon discs and rotating between the poles of a
magnet substantially as herein before described to serve as generator or motor as
in the first claim.
In witness whereof we the said John Gordon and John Gray have hereunto
set our Hands and Seals this twenty eighth day of February in the year
of our Lord, One thousand eight hundred and eighty three
JOHN GORDON (L.S.)
JOHN GRAY
(L.S.)