Year: 1887

page_text: I, HERBERT JOHN ALLISON, of 52 Chancery Lane, London, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention, which has
been communicated to me from abroad by The Baxter Electric Manufacturing and
Motor Company, of Baltimore, Maryland, in the United States of America, Manu-
facturers of Electrical Machinery, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :-
The object of this invention is more particularly to render a small electric motor
more durable and effective and convenient for operation by persons unskilled in the
use of machinery; and with this object in view the improvements consist in a
particular form of journal bearing which is adapted to operate for a long time without
attention, in an improved construction for the armature and its commutator and its
connections between the field magnet and the brushes.
They also consist in means for automatically detaching the brushes from the com-
mutator when the brushes are placed in their inoperative position, in a particular
form of bridge for uniting two inclined magnets, and in the combination with an
arched bridge, of projections for sustaining the armature bearings, and in the
combination with the arched bridge, of a bed plate having a switch secured thereon
beneath the arch so as to protect the switch from derangement. These improvements
may all of them be used in a single machine as shown in the annexed drawing, or
may be used separately in other analogous machines to which they may be adapted.
Thus, the construction for the commutator would be adapted for any other electric
motor independent of the means by which the commutator was placed upon the
spindle; and the improved journal bearings are also adapted to be used in other
motors without reference to the use of the other improvements in such construction.
In the drawing, Fig. 1 is a view of my improved motor showing the commutator end
of the frame; Fig. 2 a vertical longitudinal section of the machine on line x, x, in
Fig. 1, the armature not being shown in section; Fig. 3 an inside view of the
wooden ring j and the brush carrier p; and Fig. 4 is a longitudinal section of the
armature, commutator and spindle detached from the motor, upon a larger scale ;

page_text: Fig. 5 is an enlarged view showing the electrical connections to the brushes in their
operative position; Fig. 6 is a similar view showing the same electrical connections
in their inoperative position with the armature cut out of the circuit.
In my construction, the field magnets a are inclined in a vertical plane with the
poles at their upper ends formed of head pieces a¹ united at the top by a tie plate a².
The bases of the magnets are connected by a bridge which is formed with two
seats upon which the magnets are secured, and a central arch b', the sides of which
slope upward nearly parallel with the magnets, but diverging slightly from the same
toward their upper ends, so that the center of the arch as shown in the section in
Fig. 2 is considerably removed from the armature.
This construction affords a very long bridge within a short space, thus bringing
the field coils proportionately to the ends of the magnet and the arched frame thus
operates powerfully to concentrate the magnetic field at the central point where the
armature is located. The lower ends of the arch are provided with lugs b² by which
the machine can be secured in any position to a suitable base.
The machine may, by such lugs, be secured to the ceiling or wall of a room or to
any part of another apparatus, as the stand of a sewing machine, but is shown herein
secured to a bed plate 64 by screws 63, and the wires w from the field magnets are
carried through holes in the arch to independent clamp sockets d, d', which are
secured upon the base and connected with the line wires, through connecting
sockets and do, in rear of the first mentioned sockets.
The sockets d and d*, shown in Fig. 2, are formed in a single casting, as is usual
for connecting sockets, and secured to the bed plate b, independently of the casting
forming the corresponding sockets d¹ and d³.
The sockets d and do receive the line wires, and may be connected, when desired,
by a switch lever d² which operates to entirely cut out the motor when it is desired to
stop the same, the switch lever being pivoted to one of the castings, and sliding over
a tongue de attached to the other casting, when cutting out the motor.
The sockets are preferably provided with button head screws d³ which can be
loosened only by a screw-driver, and such construction, with the location of the
switch and sockets under the arch 1, prevents any interference of unauthorized
persons with the connections; while the switch lever is perfectly accessible for
actuation when required.
The motor is designed to be stopped and started by a cord connections to the
brush carriers, and the latter are therefore pivoted movably upon one of the journals
and provided with a spiral spring s acting in opposition to the cord s' shown in
Fig. 1. The cord may then be connected with a treadle, by pressure upon which the
machine will be held in operation, and the spring s operate to elevate the treadle and
stop the machine automatically, whenever such pressure was removed.
The journal bearings are formed as posts having their lower ends concentric with
the bearings, and mounted upon lugs f projected from the opposite sides of the
arch b¹.
The tops of the lugs, being bored out at the same time as the magnet heads a¹,
are thus rendered perfectly concentric with the armature spindle; and the posts c
being turned off upon their bases to fit such curved seats, the armature is thus readily
fitted in its required position.
The bearings for the spindle e are lined with bushings of vulcanized fibre e¹, which
material is already well known as it has been extensively used for insulating in
electrical apparatus; and my construction provides a recess c¹ around such bearing
within the head of the post c, and furnishes a cap c² at the end of the spindle to
prevent the escape of the lubricator and a screw plug c³ at the top of each bearing to
provide for the renewal of the lubricant.
The fibre bushing is shown provided at opposite sides with a hole e² to admit the
lubricator from the recess c¹. In practice, the recess c³ is stuffed with hard grease
like tallow mixed with plumbago, and I find that the anti-friction qualities of the
vulcanized fibre are so great, and the friction of the spindle in the fibre bushing so
very slight, that sufficient heat to warm the tallow is only produced at very rare

page_text: intervals when the lubricant within the bearing is entirely exhausted, and the small
supply of grease derived from such heating of the fat suffices to prevent the heating
of the bearing in any degree for a very long time thereafter; so that in practical
operation the bearing constructed as I have described, will remain efficient without
attention for several months, although running during the day time at a speed of
750 revolutions per minute. The armature is shown, in Fig. 4, as constructed of a
series of soft sheet iron disks g alternated with paper upon a wooden barrel h.
The disks are held between fibre heads g¹ which are clamped firmly upon the disks
by a collar h¹ secured to the arbor e at one end, and a nut k fitted to the arbor at the
other end of the armature.
The nut is formed with a hub to fit the thread on the spindle, and with a flange to
press upon the fibre head g¹ which clamps the armature disks firmly together upon
the barrel h.
The commutator has its sections n formed with beveled ends n¹, and secured upon
the spindle e by two nuts 1, 1, which are countersunk or recessed upon their inner
sides to embrace such beveled ends, and to clamp the same firmly to the spindle.
A non-conducting packing m is applied between the sections and the adjacent
surfaces of the nuts to insulate the same.
Each section is provided with an ear n² in which a screw n³ is inserted to
conveniently attach the armature connections o.
'
By such construction, the commutator is made very compact as it requires no
binding upon its outer surface to retain its sections in place; I thereby avoid the use
of any ring of non-ducting material such as is often applied around the sections to
hold them in place, and which material encumbers the spindle in the vicinity of the
brushes.
The brushes t are mounted upon a carrier arm p pivoted upon a sleeve p¹, which
projects from the inner side of the post around the spindle e.
The brush holder consists in a block of fibre r pivoted upon a stud fixed on the
carrier, and provided with a couple of leaf springs and ², which receive the current
from the field magnets.
Such current is conveyed to the springs by a metallic lining applied in two
independent sections within a wooden ring j, which is secured to the frame of the
machine around the brushes and concentric with the spindle.
The lining is applied in two independent pieces within the upper and lower sides
of the ring, and the connections s² and s³ from the field magnets a are attached
respectively, to such lining sections.
The springs and ² are united electrically at their base, and both of the springs
rest upon one section of the lining ³ when the motor is in operation, and thus place
the brush in communication with the corresponding field magnet. Fig. 5 shows the
springs thus arranged, and the arm p turned in its operative position with the brushes
resting upon the commutator n.
When in this position the current enters the machine by the line wire w¹ thence
through the socket d, which is formed integral with the socket d, by the wire w to
one of the magnets a, thence through the wires to one of the linings thence
through such lining and the springs 1, 2, through their connected brush, the
armature, and the opposite brush, to the other springs and ², and through the
other lining and its connection ² to the other magnet, and thence through
the other wire w to the socket d¹ and to the line, through its attached socket d³.
In Fig. 3, only the springs are shown, as the figure was designed chiefly to show
the means for cutting out the armature when the motor is at rest. To effect this the
brush carriers are arrested, when rotated by the springs to their inoperative position,
by pins 2 affixed in the edge of the ring and levers t³ are attached to the brush
blocks to bear against the pins t², and tip the blocks so that the brushes are retracted
from the commutator when the arm p is in this position.
The reaction of the springs r¹ and ², against the interior of the ring j, tends to
press the brushes elastically against the commutator with the required degree of force,
but the spring s is formed with a greater degree of power and thus serves to rotate

page_text: 1
the blocks upon their studs when the arm pis turned sufficiently upon the sleeve p
to press the levers t³ against the pins 2. The springs 1 and 2, attached to each of
the brushes t also perform the function of cutting out the armature when the motor
is at rest, by making an electrical connection between the wires s² and s³, which are
conducted to the sections of the lining 3 from the opposite field magnet poles a".
For this purpose the spring 7 is made longer than the spring ² and is arranged to
slide off of the section 3 upon which it normally operates, and to bear upon the
opposite section of the lining which connects with the opposed magnet pole. When
the arm p is turned by the springs to its inoperative position as shown in Figs. 1
and 6, the springs and therefore bear respectively upon both of the linings ³,
and serve to connect them electrically, thus furnishing a short circuit for the field
current through the two section of the lining 3 and the springs and ², which
latter are in electrical connection with one another as before stated, and thus serve
to conduct the current from one section of the lining to another instead of through
the armature, and the motive power of the apparatus is entirely destroyed and the
revolutions cease.
The cooperation of the springs and 2 with the two sections of the lining r³ thus
serve, when the carrier arm p is turned to its inoperative position, to prevent any
current from flowing through the armature.
The wooden ring j is sustained upon one of the lugs f upon the arch 6¹, and is also
braced at its upper end by an extension of the plate a².
This ring is entirely free from electrical connections upon its periphery and outer
flat side, and as it wholly encircles and covers the brushes and their electrical con-
nections, it serves in the most effectual manner as a shield to protect the latter from
accidental interference and injury.
The field magnets are detachably secured to the seats b by screws, so that they
may be removed for convenient winding, and the various parts are, in practice, made
interchangeable so that they may be produced with the utmost uniformity and
cheapness.
By the construction for the bridge the greatest possible effect is secured in the
magnetic field, while the construction for the armature with a single nut for clamping
the metallic disks g in place, obviates the use of longitudinal rods which commonly
necessitate the perforation of the armature disks and result in the disturbance of a
¡uniform magnetic action in the latter.
The construction for the bearings with the fibre bushings secures very great dura-
bility and immunity from accident in case of neglect, while the construction of the
armature, its brushes and their electrical connections affords the greatest possible
protection both to the apparatus and to unskilled parties who may be required to use
the same.
Having now particularly described and ascertained the nature of the said invention,
and in what manner the same is to be performed, I declare that what I claim is :-
1st. In an electric motor, the combination, with two field magnets inclined toward
one another as described, of a bridge connecting the bases of the magnets, and
arched toward the magnetic field as described, and provided with lugs f for sustaining
the armature, substantially as shown and described.
2nd. In an electric motor, the combination, with two field magnets inclined toward
one another as described, of the bridge b¹ formed with two seats b in the same plane to
receive the field magnets a, and arched in the middle toward the inner ends of the
magnets, as and for the purpose set forth.
3rd. In an electric motor, the combination, with two field magnets inclined toward
one another as described, of a bridge connecting the bases of the magnets, and arched
toward the magnetic field as described, and provided with the lugs f sustaining posts c
provided with bushings to form bearings for the armature spindle, as and for the
purpose set forth.
4th. In an electric motor, the spindle bearing constructed substantially as
shown and described, and consisting in the post e provided with bushing e¹, recess c¹

page_text: surrounding the same, holes e² connecting the interior of the bearing with said recess,
and a screw plug c³ for replenishing or closing the recess, substantially as herein set
forth.
5th. In an electric motor, the construction for the armature consisting in the
collar fixed upon the spindle at one end of the armature, the nut k fitted to a
thread upon the spindle at the opposite end, the barrel h of non-conducting material,
the metallic disks g and the heads g¹ pressed upon the disks by the rotation of the
nut k, all substantially as herein shown and described.
6th. In an electric motor, the construction for the commutator consisting in the
sections n having beveled ends n¹ secured upon the armature spindle by a thread
formed upon the same, and by countersunk nuts and l' clamped upon the tapering
ends of the sections by turning upon the screw thread, substantially as shown and
described.
7th. In an electric motor, the combination, with the ring ; surrounding the brushes
and provided with the metallic linings ³, in electrical connection respectively, with
the two field magnets, of the brushes provided each with a yielding spring pl
adapted to bear elastically upon one of the linings ³, as and for the purpose set
forth.
8th. In an electric motor, the combination, with the ring j surrounding the brushes
and provided with the metallic linings ³, in electrical connection respectively, with
the two field magnets, of the brushes provided each with the shorter spring and
the longer spring ², the two springs being adapted to bear elastically against the
metallic linings ³, and to form an electrical connection between the field magnets
when the brushes are in their inoperative position, as and for the purpose set forth.
9th. In an electric motor, the combination, with the ring j surrounding the brushes
and provided with the metallic linings ³, in electrical connection respectively, with
the two field magnets, of the brushes pivoted by holders upon the arm p, the spring s
affixed to the frame and operating to turn the arm and brushes to an inoperative
position, the springs operating to press the brushes toward the commutator, levers (³
affixed to the brush blocks and projected at the side of the ring j, and stops t² upon
such ring to check the levers and move the brushes away from the commutator when
the arm is thrown into its inoperative position.
10th. In an electric motor, the combination, with two flat field magnets having
their flat sides inclined toward one another as described, of a flat bridge connecting
the bases of the magnets and arched toward the magnetic field, as and for the purpose
set forth.