Improvements in Electric Motors and Dynamo-electric Machines.
Year: 1890

page_text: Date of Application, 6th Jan., 1890
Complete Specification Left, 12th Sept.. 1890-Accepted, 25th Oct., 1890
PROVISIONAL SPECIFICATION.
Improvements in Electric Motors and Dynamo-electric Machines.
We JOHN HOPKINSON F.R.S. D. Sc. of 5 Victoria Street in the City of
Westminster EDWARD HOPKINSON D. Sc. Engineer of Salford Iron Works Manchester
in the County of Lancaster and GEORGE ANNESLEY GRINDLE Engineer of 19 Great
Winchester Street in the City of London do hereby declare the nature of this
invention to be as follows:-
Our invention more particularly relates to improvements in applying electric
motors to locomotive purposes. In electric locomotives it is often desirable to have
more than one driving axle either for the purpose of increasing the adhesion or for
subdividing the driving power. This may be accomplished by having an independent
motor in connection with cach axle either driving direct with the armature motor
carried on the axle or with the armature shaft geared by any suitable means to the
axle each motor having its independent field magnets.
One of the objects of our invention is to secure the advantage of independently
driving more than one axle and at the same time to diminish the increase in weight
in the motors and the space which they occupy which results from subdividing the
power between two or more motors.
According to our invention we combine the field magnets of the motors into a
single magnetic circuit which includes the armatures the lines of magnetic force
passing from the field magnets and through the armatures in succession the armatures
having independent parallel shafts each driving one of the axles of the locomotive.
Although the magnetic circuit passing through the armatures is the same the
armatures are otherwise entirely independent and may be coupled in series or
parallel as desired or one armature may be disconnected from the axle and remain
at rest.
In order to reduce the wear on the commutators of the armatures we make use
of carbon contact pieces instead of "brushes" formed of wire or copper plates.
The use of carbon for this purpose is well known but it has generally been applied in
the form of tangential or butt contact brushes or plates of carbon.
According to our invention we form the carbon contact pieces from a carbon rod
of circular section such for instance as is commonly employed in arc lamps and
we secure it by inserting the piece of rod in a split tube or holder of brass or steel
or other suitable material into which it is firmly driven. The tube or holder may be
held in various ways, but we have found that it is convenient to attach it to a plate
preferably of brass or steel which is placed tangentially to the commutator and held
by a spindle after the manner of an ordinary brush holder. To secure the contact of
the carbon against the surface of the commutator we may either give the plate a
spring in itself or hold it in some form of spring holder or connect the plates holding
the two opposite contact pieces by a spring such for instance as a rubber or spiral
spring.
In order to facilitate the removal and replacement of the carbon contact pieces
when worn we sometimes attach the tube or holder to a smaller plate which is fixed
in a pocket or recess on or in the tangential plate thus permitting of easy removal
without disturbing the tangential plate or spindle holding it. Although this form of
contact piece is specially advantageous in the case of electric motors used for
locomotives inasmuch as the contact being symmetrical in all respects with the
commutator it is independent of the direction of rotation and cannot be tripped up
or caught when the direction of motion is reversed, it is also applicable in any form
of dynamo.

page_text: We may also make use of the arrangement we have described of a single magnetic
circuit with two or more armatures for other purposes than electrical locomotion it
being applicable in any case where it is desirable to have independent motions of
one or more shafts and considerations of weight and space render an independent
magnetic circuit to each armature inconvenient.
Dated this 6th day of January 1890
COMPLETE SPECIFICATION.
Improvements in Electric Motors and Dynamo-electric Machines.
We JOHN HOPKINSON F.R.S. D. Sc. of 5 Victoria Street in the City of Westminster
EDWARD HOPKINSON D. Sc. Engineer of Salford Iron Works Manchester in the
County of Lancaster and GEORGE ANNESLEY GRINDLE Engineer of 19 Great
Winchester Street in the City of London do hereby declare the nature of this inven
tion and in what manner, the same is to be performed to be particularly described
and ascertained in and by the following statement :—
Our invention more particularly relates to improvements in applying electric
motors to locomotive purposes. In electric locomotives it is often desirable to have
more than one driving axle either for the purpose of increasing the adhesion or for
subdividing the driving power. This may be accomplished by having an independent
motor in connection with each axle either driving direct with the armature motor
carried on the axle or with the armature shaft geared by any suitable means to the
axle each motor having its independent field magnets.
One of the objects of our invention is to secure the advantage of independently
driving more than one axle and at the same time to diminish the increase in weight
in the motors and the space which they occupy which results from subdividing the
power between two or more motors.
According to our invention we combine the field magnets of the motors into a
single magnetic circuit which includes the armature the lines of magnetic force
passing from the field magnets and through the armatures in succession the armatures
having independent parallel shafts each driving one of the axles of the locomotive.
· Although the magnetic circuit passing through the armatures is the same the
armatures are otherwise entirely independent and may be coupled in series or
parallel as desired or one armature may be disconnected from the axle and remain
at rest.
In order to reduce the wear in the commutator of the armatures we make use of
carbon contact pieces instead of "brushes" formed of wire or copper plates. The
use of carbon for this purpose is well known but it has generally been applied in the
form of tangential or butt contact brushes or plates of carbon.
According to our invention we form the carbon contact pieces of a carbon rod of
circular section such for instance as is commonly employed in are lamps and we
secure it by inserting the piece of rod in a split tube or holder of brass or steel or
other suitable material through which proper contact is made and into which it is
firmly driven. The tube or holder may be held in various ways but we have found
that it is convenient to attach it to a plate preferably of brass or steel which is placed
tangentially to the commutator and held by a spindle after the manner of an ordinary
brush holder.
To secure the contact of the carbon against the surface of the cominutator we may
either give the plate a spring in itself or hold it in some form of spring holder or
connect the plates holding the two opposite contact pieces by a spring such for
instance as a rubber or spiral spring.
In order to facilitate the removal and replacement of the carbon contact pieces
when worn we may attach the tube or holder to a smaller plate which is fixed in a
pocket or recess on or in the longitudinal plate thus permitting of easy removal

page_text: without disturbing the tangential plate or spindle holding it. Although this contact
piece is specially advantageous in the case of electric motors used for locomotives in
as much as the contact being symmetrical in all respects with the commutator it is
independent of the direction of rotation and cannot be tripped up or caught when
the direction of motion is reversed, it is also applicable in any form of dynamo.
We may also make use of the arrangement we have described of a single magnetic
circuit with two or more armatures for other purposes than electrical locomotion it
being applicable in any electrical machine where it is desirable to have independent
motions of one or more shafts and considerations of weight and space render an
independent magnetic circuit to each armature inconvenient.
In order to more fully explain our invention and the manner in which the same
may be performed we refer to the accompanying drawings wherein Figure 1 is an
end elevation and Figure 2 is a side elevation of a motor suitable for locomotive or
other purposes with a single magnetic circuit the lines of force passing through two
armatures in succession.
The reference letters in these figures refer to the same parts.
In Figures 1 and 2 the armatures a, a, are shown with their shafts parallel and
enclosed in the pole pieces b₁ b₁₂ b3 which form part of the single magnetic
circuit b₁ b₂ b, dec. The exciting coils are wound on the limbs c and d and also on
the yoke pieces e if required..
The armatures a₁ a, are quite independent of each other and may be coupled in
series or in parallel, or if desired one may be kept at rest whilst the other is in
motion.
The power given out by the motor may be transmitted from both armature shafts
to the same or to different axles by means of various forms of gearing such as for
instance belts connecting rods spur gearing or friction gearing.
For the sake of illustration we shew in Figures 1 and 2 the motor with two
armatures driving a locomotive or vehicle with two axles, each armature driving each
axle independently by means of connecting rods 11, the axle boxes being inclined so
that their centre line is at right angles to the connecting rods, so that the variation
in the distance between the centres of the crank pins may be a minimum as the motor
rises and falls with the springs of the locomotive.
We may also apply such a motor with two or more armatures and a single
magnetic circuit as we have described when the axles of the locomotive or vehicle
form the shafts of the armatures and gearing is dispensed with.
This form of motor although here described more particularly for locomotive
purposes may be used for any other purpose where it is desired to subdivide the
power and at the same time to minimise the weight of the motor or the space
occupied by it.
In Figures 3, 4, and 5 are shown cross sectional side and longitudinal views
respectively of a carbon contact maker constructed according to our invention.
The carbon contacts are shown at f and consist of pieces of round carbon rod such
for example as is used in arc lamps. These pieces are carried in tubes g which
clamp them and hold them securely in place. Each tube is shewn as being attached
to or forming part of a slide piece h. Each slide piece is carried in guides fixed
to the plates i which are held tangentially to the commutator by the holder j carried
on the spindle k by any convenient device. With this arrangement the pocket or
slide carrying the carbon contact piece can be easily and quickly withdrawn and
replaced, but where to provide for this is unnecessary the slides may be omitted and
the tubes be attached to the brass plate by any suitable means.
The contact of the carbon against the surface of the commutator is secured either
by giving the plates i a spring in themselves or by making the holder ja spring
holder, or by connecting the plates by a spring, such as the spiral spring p shown in
Figure 3.
The said contact pieces may be applied to other electrical machines than motors for
locomotives they being applicable to all forms of motors and dynamos.

page_text: Having now particularly described and ascertained the nature of our said inven
tion and in what manner the same is to be performed, we declare that what we
claim is
First. In electric locomotives or in vehicles propelled by electric motors the
combination of two or more armatures having independent parallel shafts, each
driving an axle or axles, with field magnets arranged so as to form a single magnetic
circuit, which includes the armatures the lines of magnetic force passing through, the
armatures in succession.
Second. The construction of contact pieces or brushes for commutators from a
carbon rod held in a split tube or holder of brass or other metal or material through
which contact is made.
Third. Carbon contact pieces constructed as described in combination with metal
plates to which they are attached as shown in Figures 3, 4 and 5 and which are placed
tangentially to the commutator and held by a holder and spindle, the contact against
the commutator being obtained by spring in the plates or by a spring in the holder,
or by connecting the opposite plates by a spring.
Fourth. The combination of the carbon contact piece and split tube or holder with
a smaller plate to which the tube is attached, with a pocket or recess on the tangential
plate as, and for the purpose herein before described.
Fifth. The combination of the single magnetic circuit and two or more armatures
substantially as and for the purposes herein before described.
2
1000
JOHN HOPKINSON,
By his Agents, J. H. Johnson & Co.
EDWARD HOPKINSON.
GEORGE A. GRINDLE.