with, Especially Applicable to Purposes of Locomotion.
Year: 1889

page_text: with, Especially Applicable to Purposes of Locomotion.
I, ALFRED JAMES JARMAN, of 82 Kellett Road Brixton, in the county of Surrey,
Electrical Engineer 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 :-
My invention relates to the construction and application of electric motors to
tramway and railway locomotion, and is based upon the subject of my invention of
prior date, described in the specification of my patent, No. 2783, of A.D. 1886; and
has for its objects,
First. The arrangement of two separate armatures upon a single axle, so that one
may revolve in one direction, and perform work, while the other armature is revolving
idly, and dissipating heat acquired while running with the load; by radiation in an
induced current of cold air within the inert field magnet.
Second. Certain mechanical devices, hereinafter to be fully described, for facilitating
the removal of either armature without interfering with the other.
Third. The provision of electrical contacts whereby the reversal of the direction
of rotation may be obtained, whether a single or double armature be used.
Fourth. A method of winding the field magnets of electrical motors constructed
according to my invention, by means of which the power, or mechanical work
performed by, said motors may be varied at will, without the interposition of idle
resistances into the circuit, or by altering the connections from the source of power,
such for instance as cutting out cells of an accumulator. I prefer to style this
system of winding said field magnets the "gaunt" winding and I also provide means
for varying the resistance, and "ampère turns upon the magnets at will.
"
Fifth. The construction of an armature core in which the cross sectional area of
soft iron is not lessened by excessive lamination, and yet provision is made for the
neutralization of Foucault currents in said core.
In order that my said invention may be clearly understood I have appended the
accompanying two sheets of drawings, in which Figure 1, sheet 1 represents a side
elevation of two armatures upon one spindle according to my invention, partly in
[87]

page_text: section. Figures 2 and 3 represent the forms of clutches adapted by me to the
improved electric motor. Figure 4 is a longitudinal section of a double commutator,
applicable to single or double armatures, and Figure 5 is a cross section of the same
upon the line A B. Figure 6 is a diagram, illustrative of the method of arranging
the electrical couplings or connections between the armature and the bars of the
double commutator. Figure 7 shews the arrangement of sliding brushes, applicable
to the double commutator above referred to, for reversing the direction of rotation,
and Figure 8 shews a ring, forming part of an armature core according to my present
invention.
"
Figure 9, Sheet 2 is a section of a field magnet bobbin or coil, shewing the
gamut" winding, hereinbefore referred to, and Figure 10 is a diagram shewing the
coupling or connection thereof. Figure 11 is a vertical section of the switch or
contact barrel employed by me to effect the required variation of the speed and power
by the "gamut" winding, Figure 12 is a plan view of the top of the same, and
Figure 13 a cross section of the barrel, showing the formation of one of the contacts,
and Figure 14 is a general view of two armatures, illustrative of the most important
feature in my said invention, namely, the employment of two armatures upon one
spindle for the purpose of allowing one to cool while the other is performing work.
Similar letters of reference, where it is convenient, indicate corresponding parts
throughout the several views in the two sheets of drawings.
A
In carrying my Invention into effect I build up an armature core preferably of a
series of rings, shewn by Figure 8, which are split at a for the purpose of interrupting
the circuit formed by the body of said ring, and so neutralizing Foucault or oddy
currents, caused by the rotation of the iron ring in the magnetic field. Said rings
being placed together, side by side, as shewn by b b 61, Figure 1 sheet 1, to form
either a ring, drum or disc armature, suitable insulation being placed between them,
I mount the whole, previously to placing upon the spindle, upon a sleeve s. Said
sleeve s is arranged so as to fit upon the spindle S freely, sliding upon a feather
bedded thereupon. One end of said sleeves is rigidly attached to a clutch e, and the
commutator k is placed upon the opposite end of said sleeves being mounted upon a
separate sleeves for the purpose of facilitating removal when necessary. A nut n
upon the free end of said sleeve s serves the dual purpose of keeping the commutator k
and its sleeve & in position, and also forming a shoulder or journal thrust for the end
bearing of the spindle S. The clutch is provided with any suitable form of jaw or
cam, either shaped radially as shewn by Figure 2, or simply a bar or projection with a
corresponding recess, as shewn by Figure 3. The pinion P, used for transmitting the
motion and power of the electric motor armatures A A¹ to the machinery or the like
to be driven, is rigidly attached to the spindle S by keying or equivalent means.
clutch jaw j formed thereupon, on both sides allows both armatures to be pushed upon
the spindle S, the sleeves s sliding freely thereon, until the clutch c engages with the
projection or jaw j upon the pinion P. By means of this arrangement I am enabled
either to slide one of the armatures off the spindle without interfering with the other
armature, or I may remove either commutator k, since these are mounted upon
separate sleeves s'. I wish it to be understood that I do not confine myself to the
employment of any particular form of clutch in the foregoing arrangement, and it is
also applicable to a drum ""dise" or "ring" armature. In cases where I do not
consider it advisable to lift the brushes or to depress them in order to transfer the
electric current from one armature to another, in order to produce rotary motion in
either direction, I may employ a double commutator shewn by the longitudinal
section, Figure 4, and the cross section on line A B. Figure 5. These commutators
are built up of bars in the usual manner, and are mounted upon a sleeve which is
fitted upon the sleeve s carrying the armature or armatures. Suitable conical
washers o 0 are provided at each end for the purpose of holding the bars in
position, and said washers o are of course constructed of suitable insulating material.
A central conical wasber m retains the bars of both commutators in place, when the
lock nuts are tightened upon the screwed end of the sleeve s¹, and the cones are
thereby compressed. An insulating bush B, preferably formed upon the conical washer o

page_text: that is close to the shoulder or collar of the commutator sleeve s', serves
to insulate the bars of the commutators from the armature sleeves and
spindle S. In order to provide for the connection of the bars of the outer
commutator with the armature coils, I drill a number of holes through the
shoulder or collar of the sleeve s', and continue said holes through the substance of
the bush B, providing an angular slot, or other device as an outlet for each hole,
directly under the bars of the outer commutator as shewn. Wires P, of a number
corresponding to that of the coils upon the armature, and the bars of the commutators,
are passed through the holes above referred to, and being bent up so as to protrude
through the angular slots or orifices forming the termination of the holes, admit of
electrical connection between the ends of said armature coils and the bars of the outer
commutator. The inner commutator is connected by the wires q or by other equivalent
means to the coils above referred to. The diagram, Figure 6, illustrates the manner
of connecting the inner and outer commutators, so that a reversal of the direction of
rotation may be obtained by moving the brushes or other device from one commutator
to the other. The coils of wire upon the armature are coupled in the usual manner
to the bars of the inner commutator, which is nearest to said armature, and a second
wire, coupled to the same end of each coil, is connected to one of the bars of the outer
commutator as shewn by p. Figure 4, the bars, however, of the inner and outer
commutators respectively which are coupled to the same coil, not being parallel to each
other, but so arranged as to present the opposite angle of commutation, so that a single
pair of brushes, arranged to move in a longitudinal direction, may, when so moved
have the same effect in reversing the motion as would occur if said brushes were
moved radially to the opposite angle of commutation upon a single commutator.
Referring to Figure 7, the brushes B, B' are shown resting upon, and making contact
with, the commutator K, and the dotted outline of said brushes B, B¹ upon the com-
mutator K' shews the altered position thereof when it is desired to reverse the direction
of rotation. I may, in carrying out my invention, make use of the foregoing device
in combination with the double or compound armature shewn by Figure 1, placing
the double commutator constructed in the manner above described upon each end
thereof, in place of, and as a substitute for, the single commutators shewn upon the
drawing.
I have hereinbefore stated, that the chief feature of my said invention is based upon
the subject of my prior patent, No. 2783 of A.D. 1886, and consists in the employment
of a double or compound armature for the purpose of providing for the reduction of
the high temperature induced and caused by the passage of the electrical current
when work is performed; and in order to attain this end I have devised the various
improvements in the general construction of the electric motors that are herein fully
set forth. I may, however, in certain cases, employ a double set of brushes arranged
so as to be placed in contact with either the single commutator at both ends of the
armatures, as shewn by Figure 1, or the double cominutator shewn by Figures 4, 5,
and 7, so that, when necessary for the application of greater power to the mechanism
operated by the motor or motors, both armatures may be actuated by the electric
current at one time, and revolve in the same direction. An electrical motor, when.
applied to purposes of locomotion, such as to traction upon trainways or railways,
cannot work efficiently when a single armature is employed, for the reason that greater
power has to be developed in order to overcome the ris inertia when starting the vehicle,
or train of vehicles from a position of rest, than is required to maintain the motion at
the required rate of speed. And it is also an established fact, that in order to obtain
the highest efficiency of an electric motor, the armature must attain that velocity of
rotation known as the "critical speed," or in other words, the speed at which the
maximum of mechanical work is performed with the minimum absorption of electrical
energy. Thus, when a single motor is employed for this purpose, it develops the
lowest efficiency at the time when the work imposed upon it is greatest, namely, when
starting the vehicle or vehicles from a position of rest. For this reason, and to obviate
this disadvantage, I prefer, where practicable, to provide means for enabling the two
armatures according to my invention, to be both operated by the electric current,

page_text: and to act in unison upon the mechanism that is to be driven, when the power required
is in excess of that developed by a single motor or armature, and this may be done
by the employment of a double set of brushes as hereinbefore described, or by any
equivalent device for attaining the same result. In electrical traction, however, the
necessity for this excess of power exists but occasionally during an ordinary journey,
and ample time is allowed for one armature to become cooled, ready for use during
the return journey, according to the principle of my said invention.
It has hitherto been customary to provide for the regulation of electric motors,
by the employment of a series of resistance coils which may be placed in the circuit,
or cut out at will, and by the interposition of extra resistance, the current is diminished
and the speed and power consequently varied to meet the requirements of the work.
This method is not economical, since the electrical energy is absorbed in heating the
idle resistance coils above mentioned, and is also an element of danger, tending to set
fire to the woodwork in the proximity of said coils.
«
32
To provide a more efficient method of regulating the speed and power of an electric
motor, I have devised the system of winding the field magnets, styled by me gamut
winding and forming a part of my present invention.
Figure 9, Sheet 2, of the accompanying drawings, represents a section of one of
the bobbins, or field magnet coils of an electric motor, wound in this manner.
One or
more layers of wire is or are wound upon the shell of the bobbin, or upon the core of
the field magnet, and the ends of said coils formed by this layer or number of layers;
are passed through the flanges or ends of the bobbin, or otherwise left free for
subsequent connection. One or more layers of wire of different diamater, (or if of
the same diameter as that of the first layer or layers, of different material and con-
ductivity) is wound over, and upon the first layer or layers above mentioned, and over
and upon this or these, other layers are wound, the ends thereof being left free for
connection, as provided in the case of the first layer or layers. In order to obtain a
variable resistance, which also with each degree of variation bears a definite relation
to the ampère turns of the field magnets, I may either wind the separate layers of
the "
gamut" winding with wire of different diameters, in which case the metal or
material of which said wires are composed may be of the same nature, and conductivity
throughout, the varying resistance being due to the varying sectional areas of the
several layers; or I may employ wire of the same diameter and sectional area throughout,
but composed of different metals or alloys, of different degrees of conductivity. I may
also, in other cases, wind all the layers with wire of the same sectional area throughout.
and possessing the same degree of conductivity in relation to the length thereof, the
varation of resistance being obtained by varying the length of wire, and
number of turns in each layer. By providing a suitable switch, or moveable
contact, I am enabled to place each of these separate layers forming the gamut"
winding into the electrical circuit, in "series " with the layer or layers already
included in said circuit, at wlll, and in a similar manner cut them out of the circuit in
succession, and thereby obtain the necessary regulation of the electric motor
according to my invention. The diagram at Figure 10 sufficiently illustrates the
method adopted by me of arranging the contacts, so that a second layer, or series of
layers of wire upon the "gamut" field magnet winding may be placed in series with
the first. The end 7 of the first layer is permanently coupled to one of the terminals T'
of the source of electric energy, and the current, entering the coils by this end,
leaves by the opposite end 11. A switch or moveable contact is provided with a
projecting strip of metal o, which, when placed as shewn by the diagram, connects
the end of the first layer, by which the current leaves, to the commencing end of
the second layer. The terminal end of this layer 1111 is, by the same movement of the
switch, brought into contact with a pin or plug a, in metallic contact with the spindle
of said switch, from which said current is led to the commutator C of the motor M
by the brush b, the other brush 61 being coupled to the opposite terminal T of the
generator or other source of power, thus completing the circuit, and placing both
layers in series. If, however, the switch or moveable contact be turned round so that
the metallic strip o no longer electrically connects the wires and ", but that the
<<

page_text: plug n makes contact with the end of the first layer, the second layer is cut out of
the circuit, which is then completed from 1, through n, and the brushes b and b¹ to the
terminal T. It is evident that the operation above described may be repeated with
any number of layers in a "gamut" winding successively, if the strip o be extended
sufficiently round the circumference of the cylinder K of the switch or moveable
contact, so as to preserve the electrical connection between and while the other
layers are successively included in the circuit.
In order to effect the regulation of the electric motor or motors according to the
above mentioned method, in a convenient manner, so as to be easily under the control
of an attendant, I employ a switch, or moveable contact, shewn by the longitudinal
section, Figure 11, and the plan view, Figure 12. A cylinder K, of any suitable
insulating material is mounted upon a metallic spindle S. within bearings in a caso
or hox B, so that it may be partly revolved by a lover or handle H, upon a quadrant I,
within the range of stops and s¹.
Strips of metal 0, o and o are attached to the outer circumferential surface of
the cylinder K, and are of sufficient width to electrically connect any pair of the
contact tongues m of the series, which represent the ends of the various layers forming
the "gamut" winding. Said strips o, o' and o¹¹³, are also formed of various lengths,
corresponding to the part of a revolution of the handle H at which contact is to be
made between any pair of tongues in, and also to be maintained while other layers are
to be placed in series with those already included in the circuit. The plugs n, n¹
and n are also placed in such a position upon the surface of the cylinder K as to
establish electrical contact between the spindle S and the tongue connected with
the termination of the last layer that has been placed in circuit, suitable con-
nection b serving to couple said spindle S to the brush, or other part of the circuit
so as to complete the same. The shape of the contact tongues m, and the manner
of insulating, connecting and manipulating the switch or moveable contact is shewn
by the cross section of the cylinder K, at Figure 13. A rounded projection p upon
the lower side of each tongue m enables contact to be made either with the strip o
or plug n, said tongues m being sufficiently elastic as to establish a good temporary
contact without vibration or undue resistance between the points thereof. The
cylinder K may be of any suitable length, and may carry any number of strips o
and plugs n so as to correspond with any number of layers upon the gamut winding,
and the action of the handle or lever H may be similar to that of the regulator
of a steam locomotive, both in its own movement, and the effect thereof upon the
mechanism operated by the electric motor or motors. I do not, however, in the
foregoing arrangement, confine myself to placing the several layers forming
the gamut" field-magnet winding, in series with each other, but may so arrange
the contact strips and plugs upon the cylinder K so as to place either the layers
individually into "parallel" or multiple arc, or "series multiple" with each other,
or I may vary the coupling of the members of the field magnets by a suitable
arrangement of said switch or moveable contact, in order to procure the efficient
regulation of the electric motor.
A plan view of the general arrangement of the double or compound motor herein-
before described, is shewn by Figure 14, which fully illustrates the principle claimed
by me as a practical system of applying electric motors to locomotive purposes
generally, the alternative direction of rotation of each armature being shewn by the
position of the brushes upon the commutators at both ends thereof.
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
1 claim is ;
First. The general arrangement and employment of a double or compound
armature as shewn by Figure 1, so that for purposes of cooling and efficient
working, either armature may be used alternately, revolving in an opposite direction
when idle, to that in which it revolves when actuated by the electric current, substan-
tially as described.

page_text: Second. In an electric motor, the employment of a sleeves Figures 1, 4, and 5
upon which the armature, may be mounted, for facilitating removal from the
spindle S, substantially as herein described with reference to the accompanying
drawings.
Third. In an electric motor as referred to in the preceding claims, the employment
of a clutch c substantially as and for the purposes herein set forth, with reference to
Figures 1, 2, and 3 of the accompanying drawings.
Fourth. In an electric motor, the employment of a double commutator, shewn
by Figures 4, 5, 6 and 7, which may be applied to one or both of the armatures,
substantially as and for the purposes herein set forth and shewn by the drawings.
Fifth. In an electric motor, the construction of an armature core, or armature
cores of a series of soft iron rings split in the manner shewn by Figure 8, substantially
as and for the purposes herein described and set forth.
Sixth. In an electric motor, the employment of the differential winding herein
styled "gamut" winding, for effecting the regulation of the speed and power of
said motor, substantially as set forth.
Seventh. In connection with the system of winding referred to in the preceding
claim, the construction and employment of a switch or moveable contact, and
connections therefor, shewn by Figures 10, 11, 12, and 13 in the accompanying
drawings, substantially as set forth.
Eighth. In a switch as above referred to, the application of a barrel or cylinder K,
Figures 10, 11, 12 and 13, with contact strips o, o o"; plugs n, m, n, tongues m and
handle or lever H substantially as and for the purposes herein described, and shewn by
the accompanying drawings...
Dated this 11th day of April 1883.
FREDK, WALKER & HYDE,
4; Little Moorfields, London, E.C.,
Agents for the Applicant.