Improvements in Dynamo Electric Machines and Electro Motors.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Dynamo Electric Machines and Electro Motors.
I, ALFRED WILLIAM MARSHALL, Electrical Engineer, of 180 Loughborough Road,
Brixton, in the County of London, do hereby declare the nature of this invention
to be as follows:-
This invention relates primarily to small dynamo-electric machines, and has for
its object, to construct the same in such a manner, that large numbers of them may
be rapidly made, and with a minimum of cost; but my improvements, or a part
of them, may be applied also to dynamos and motors of medium size.
In the case of two-pole dynamos with upright horse-shoe field-magnets, which
type I prefer for very small machines, I make the bed plate and the two standards
which support the horizontal armature shaft, of one casting, and the horse shoe
field magnet also of a single casting, the yoke of which is turned in the lathe
concentrically to the armature shaft, and rests on a concentrically machined concave
face of the base plate.
The yoke of the field magnet need only be turned at the ends, so that instead
of forming a complete segment of a cylinder, it forms two narrow segments separated
by a gap, in which case the seat or face on the base plate is also composed of two
narrow concave segments separated by a gap.
Each of the two standards supporting the armature axle, instead of forming an
ordinary axle-bearing, is preferably provided with a vertical slot and a bore adapted
to receive a cylindrical bush through which passes the armature axle.
In putting the parts together, the armature is first mounted on the axle, then
the axle is laid upon the standards by introducing it through the said slots, and
then the bushes are applied over the ends of the axle and caused to slide into the
respective standards which have been bored out to fit the diameter of the bushes.
The horse-shoe field-magnet is placed in its proper position relatively to the
armature, before the axle is laid upon the standards, so that the mounting of the
field magnet upon the bed plate and the laying of the axle into the standards
may be done simultaneously. After the bushes have been slid into the standards,
they are secured therein by means of set screws.
To take to pieces such a dynamo, the screws securing the bushes in the standards,
and the screws which secure the base or yoke of the horse shoe magnet to the base
plate, are released, the bushes are shifted along the armature shaft until they are
clear of the standards the armature shaft, together with the armature and the
field magnets, is lifted out, after which the armature shaft, together with the arma-
ture, is removed from the field magnet.
By designing a dynamo or motor in the manner described, nearly the whole
work of manufacture is reduced to casting, turning and boring, and the fitting
is reduced to a minimum, while corresponding parts of different machines are
rendered interchangeable.
The cylindrical base or supporting surface of the field magnet may have a
shoulder, or a circularly curved ridge fitting into a circularly curved gooove formed

page_text: in the supporting surface of the bedplate, to prevent longitudinal shifting of the
field magnet on the bed plate.
The same principle of construction, that is, the fitting together of the field mag-
nets with the bed plate or axle bearing by means of turned surfaces concentric
to the armature shaft, and the mounting of the armature shaft in slotted bearings
by means of cylindrical bushes as described, is applicable also to other types of
dynamos and electro motors, without departing from my invention.
Dated this 7th day of January 1897.
FAIRFAX & WETTER,
Agents for the Applicant.
'
Improvements in Dynamo Electric Machines and Electro Motors.
I, ALFRED WILLIAM MARSILALL, Electrical Engineer, of 180 Loughborough Road,
Brixton, in the County of London, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
This invention relates primarily to small dynamo-electric machines, and has for
its object, to construct the same in such a manner that large numbers of them may
be made rapidly, and with a minimum of cost; but my improvements, or a part
of them, may be applied also to dynamos and motors of medium size.
In the accompanying drawings Figs. 1 to 3 represent an overtype machine
embodying my invention, Fig. 1 being an end elevation, Fig. 2 a side elevation,
and Fig. 3 a plan of the same. Figs. 4 to 6 represent a single coil overtype
machine and Figs. 7 to 9 an undertype machine.
In the case of two-pole dynamos with upright horse shoe field magnets of the
overtype as represented by Figs. 1 to 3 which I prefer for very small machines I make
the bed plate A and the two standards B which support the horizontal armature
shaft C of one casting, and the horse shoe field magnet I also of a single casting,
the yoke D¹ of which is turned in the lathe concentrically to the armature shaft,
and rests on a concentrically machined concave face a of the base plate A.
The yoke D¹ of the field magnet need only be turned at the ends, so that instead
of forming a complete segment of a cylinder, it forms two narrow segments
separated by a gap d, as shown, in which case the seat or face on the base plate is
also composed of two narrow concave segments a separated by a gap.
Each of the two standards B supporting the armature shaft C, instead of forming
an ordinary axle bearing, is bored out and provided with a vertical slot to receive
a cylindrical bush E through which passes the armature axle.
Ġ indicates an ordinary armature, which may be of the drum or of the Gramme
type, H an ordinary commutator and I a driving pulley. The coils, commutator
brushes, connecting wires and terminals are not shown in the drawing.
In putting the parts together, the axle carrying the armature is laid upon the
standards by introducing it through the said slots b, and then the bushes E are
applied over the ends of the axle C and caused to slide into the respective standards
which have been bored out to fit the diameter of the bushes.
The horse shoe field magnet is placed in its proper position relatively to the
armature, before the axle is laid upon the standards, so that the mounting of the
field magnet upon the bed plate and the laying of the axle into the standards
may be done simultaneously. After the bushes have been slid into the standards,
they are secured therein by means of set screws F, and the field magnet is secured
to the base by means of a screw K passing through the centre of the yoke D¹,

page_text: To take to pieces such a dynamo, the screws securing the bushes in the standards,
and the screw which secures the base or yoke of the horse shoe magnet to the base
plate, are released, the bushes are shifted along the armature shaft until they are
clear of the standards, the armature shaft, together with the armature and the
field magnet, is lifted out, after which the armature shaft, together with the arma-
ture, is removed from the field magnet.
By designing a dynamo or motor in the manner described, nearly the whole
work of manufacture is reduced to casting, turning and boring, and the fitting
is reduced to a minimum, while corresponding parts of different machines are
rendered interchangeable.
The cylindrical base or supporting surface of the field magnet may have a
shoulder, or a circularly curved ridge fitting into a circularly curved groove formed
in the supporting face of the bedplate, to prevent longitudinal shifting of the field
magnet on the bed plate.
In the electro-motor represented by Figs. 4 to 6, the two limbs D D of the field
magnet are connected by a cylindrical core D' on which is wound the magnetising
coil.
The curved faces a, a of the baseplate A may be provided with grooves a¹ into
which fit tongues d formed on the correspondingly turned faces of the field
magnet D. Instead of the single screw K inserted into the yoke as shown in
Fig. 1, there are two screws K' passing through the turned faces of the field
magnet. If it is desired to turn the curved faces a, a on the lathe, the faces
must be raised considerably above the baseplate A, or the latter must have in
the centre a recess slightly wider than the faces a, a, as indicated in Figs. 4 and 5
by dotted lines, and in Fig. 6 by full lines.
In the undertype machine represented by Figs. 7 to 9 the pole pieces of the
horse shoe magnet rest on the correspondingly turned faces a, a, of the baseplate.
These faces are formed on four lugs or standards A' A' extending upward from the
base plate A, and leaving sufficient room for the pole pieces of the field magnet
to pass between. The four segmental flanges d, d may or may not be turned
inside where they face the armature, and are turned outside to fit the concave
faces a, a.
After the flanges d, d have been mounted on the lugs A', they are
secured in position by means of four screws K', as shown.
The same principle of construction-that is, the fitting together of the field
magnets with the bed plate or axle bearings by means of turned surfaces con-
centric to the armature shaft, and the mounting of the armature shaft in bored
and slotted supports by means of cylindrical bushes which supports are made of
one piece or permanently connected with each other is applicable also to other
types of dynamos and electro-motors, without departing from my invention. The
field magnet may be composed of two or more pieces permanently fixed together,
the screws K and K' may he placed differently, instead of standards B, other
suitable supports may be used for holding the bushes, and instead of securing
each of the bushes by means of a screw F, as shown, other known means such as
a clamping screw passing across the slot above the bush, may be used for this
purpose.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. In dynamo-electric machines and electro-motors the combination of a bed-
plate forming with the standards or supports for the armature shaft a rigid piece
or single casting, and having a supporting face or faces turned or machined
concentrically to the said shaft, with a field magnet having a supporting base
turned concentrically to the armature shaft and adapted to fit upon the said
supporting face or faces, substantially as described and for the purpose specified.
2. In dynamo-machines and electro-motors, the combination of the armature

page_text: shaft, with a pair of cylindrical bushes, and a pair of bored and slotted standards
or other shaft supports made of one piece or permanently connected with each
other, substantially as described.
3. A dynamo-electric machine or electro-motor, having a base plate and a field
magnet constructed and fitted together in the manner substantially as described 5
and illustrated by the drawings Figs. 1 to 3, 4 to 6, and 7 to 9.
Dated this 15th day of September 1897.
FAIRFAX & WETTER,
37 and 39, Essex Street, Strand, W.C., Agents.