Improvements in Governing Electric Motors.
Year: 1892

page_text: Date of Application, 15th Nov., 1892-Accepted, 31st Dec., 1892
Improvements in Governing Electric Motors.
I, BENJAMIN JOSEPH BARNARD MILLS of 23 Southampton Buildings in the
County of Middlesex, Patent Agent, do hereby declare the nature of this inven-
tion, a communication to me from Robert Lundell, of No. 44 Broad Street, in the
City, County and State of New York, in the United States of America, Inventor,
and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement, reference being had to the
accompanying drawings and to the figures and letters marked thereon:-
The object of the present invention is to provide a simple method and means for
governing the speed of an electric motor, and at the same time keeping the torque
thereof constant at the several speeds. Most of the motors now in use have only a
small range of speed, and cannot be run at the lowest speed without danger of
burning out, or without sacrificing efficiency, while by the present improvement
both of these objections are obviated. Several methods of governing electric
motors have been devised by which the speed can be varied from a few revolutions
per minute up to full speed with safety, but in these cases, the methods or the
apparatus are so elaborate that they are not considered practical for ordinary
commercial purposes, such as governing the speed of street car motors, in which
case, it is very desirable to have a wide range of speed, such as is readily obtained
with an ordinary steam locomotive. With such locomotive, it is possible to obtain
a maximum torque while at rest, and to vary the speed from nothing to full speed
while keeping the torque practically constant, although it will be slightly
diminished at the highest speeds, and the torque will depend upon the train
resistance. The ideal speed regulation of a steam locomotive is made the basis of
the present improvement.
In carrying the invention into effect, I provide the dynamo-electric machine
used as an electric motor with two or more independent coils or sections of coils
upon its armature, and also two or more independent coils or sections of coils
upon its field-magnet. This construction enables to be altered both the relation to
each other in which the armature sections are connected, and also the relation to
each other in which the field-magnet sections are connected, and by doing this, the
speed is changed by the change in the armature connections without varying the
strength of the field-magnet and, therefore, without practically altering the torque.
If the armature alone was wound sectionally with its coils in series with the field-
magnet coils, the change of the armature sections from series to multiple arc with
each other would affect the strength of the field-magnet and so change the torque,
and on the other hand, if the field-magnet alone is sectional a change in the relation
of its coils produces a comparatively slight variation in speed, but by altering both,
the speed is changed by the variation of the armature coils while the field-maguet
remains constant. It is preferred to connect each section of the armature winding
in series with a section of the field-magnet winding, and the motor, therefore, is
wound with two or more circuits, each circuit comprising in series a section of the
armature and a section of the field-magnet. Suitable switching mechanism is
provided by which the relation of these circuits to each other is varied from-series
to parallel or multiple arc relation, such switching mechanism being preferably
constructed so that the direction of rotation of the armature may be reversed
thereby. To provide for intermediate variations of current a resistance may also
if necessary be provided which at certain positions of the switch is introduced in
the circuit of the motor and at other positions is removed from the circuit.

page_text: In the accompanying drawings illustrating the invention,
Figures 1, 2, 3 and 4 are diagrammatic views showing the invention in several
different forms;
Figure 5 is a side view of a switch mechanism adapted to vary the motor coils,
the front of the case being removed and some of the minor parts of the switch being
omitted;
↓
Figure 6 is a cross-section on line, of Figure 5 ;
Figure 7 is a central longitudinal section of the switch drum and contacts, the
section being taken to cnt the contact plates on line z, z of Figure 9 ;
Figure 8 is a cross section of the drum ;
Figure 9 illustrates one arrangement of contact plates which may be adopted,
the view showing the surface of the drum developed, and showing also a diagram
of circuit &c.;
:
Figures 10 10B 10° 10% and 10 show side views of the several contact
plates; and:
Figure 1 is a section of one of said plates on line y, y of Figure 10^.
In Figure 1, is shown a series wound motor, the armature 1 of which has two
commutators 2, 3 on shaft 4. The armature is wound with two separate wires,
preferably having an equal number of turns and the same, resistance and sym-
metrically distributed around the armature core. One of the armature coils is
connected to the segments of the commutator 2, and the other coil is connected to.
the segments of commutator 3, but, for the stake of simplicity these wires are not
shown in the drawing. Bearing on commutator 2 are two brushes 5, 6 connected
respectively to the circles 7, 8 which represent switch-brush, springs or similar
contact devices. Bearing on commutator 3 are two brushes 9, 10, connected.2
respectively to similar brushes 11, 12. The field-magnet has two coils 13, 14, the.
terminals of the fornier being connected respectively to the, brushes, 15, 16 and the
terminals of the latter being connected to the brushes 17, 18, 19, 20 are switch-
brushes or contact devices, to which the incoming line 19', which is supplied with.
a practically constant potential, and the outgoing line 19" are connected, 19 being. 3
connected to 15 through the artificial resistance R.
The switch-plates or segments for changing the circuit connections are shown
below the brushes 7, 8 &c., those of the upper section being numbered consecutively
from 30 to 40, and those of the lower section being numbered consecutively.
from 41 to 58. In practice said plates are preferably mounted on the surface of an. 3
insulating cylinder forming the body of a snap-switch, and the brushes 7, 8 &c. will
stand between the two sections of plates when the circuit is open, so that the motor
can be made to move forward by turning the switch in one direction from its
normal position, and in 'the opposite direction by turning said switch oppositely,
but the contact-plates should be so arranged that they will move in relation, to the 4
brushes in the direction indicated by the arrows at the, left of the figure. The
parts are not shown in the diagrams in the exact relation above indicated, since it.
would require crossing and consequent confusion of many of the lines.
With the circuit connections and switch plates as shown in this figure,, four
different speeds can be given to the motor in one direction by placing the switch 4
successively so that the brushes will stand in the lines 1, 2, 31, 41, and four speeds.
can be given in the opposite direction by moving the switch so that the brushes.
will stand successively in the lines 1", 2", 3, 4". Two of these changes of speed are...
due entirely to a change in the connection of the several coils, said changes being
so made that the strength of the field-magnet is not materially altered. The other 5
two changes are due to throwing the resistance R into or out of circuit in connection
with the commutation of the coils. If the switch be moved to position 1', the
circuit will be from brush 19 through resistance R, to coil 13, brush 16, plate 31,.
brush 7, commutator brush 5; armature coil to brush 6, to brush 8, plate 32,
brush 17, field magnet coil 14, brush 18, plate 33, brush 11, commutator brush 9, 53
through the second armature coil in the same direction as through the first, coil, to
....

page_text: '
commutator brush 10, to brush 12, plate 34, and to the terminal 20 of the out-
going line 19.
Thus all the field-magnet and armature coils and the artificial
resistance are in series, and the field-magnet and armature coils alternate so that
they will come into circuit properly as succeeding changes in their connections are
made. This movement of the switch starts the motor slowly. By moving the
switch to position 2', resistance R is cut out of circuit and the speed of the motor.
thereby increased to say one-half the full speed for which the motor is constructed
to run and with full torque. By moving the switch to position 3', one field-magnet
coil and one armature coil in series are thrown into multiple arc with the other
like coils, R being in the motor circuit, and the speed will be further increased but
the strength of the field-magnet will not be changed by the change in coil con-
nections, since while the current through the field-magnet coils is increased by the
reduction of resistance, owing to the fact that the field-magnet and armature coils
are now in multiple series instead of in series, the number of ampere turns in the
field-magnet coils remains the same, because while we have doubled the current,
only one-half of it is sent through each field-magnet coil.
Of course, as the regulation is effected in part by throwing the resistance R into
or out of circuit to enable additional speed regulations to he obtained without
multiplying the number of armature coils, the strength of the field maguet will be
varied by the change in current on the line due to the cutting in or out of said
resistance. It will be clear that if only two speeds are needed the resistance may
be entirely omitted, but it is desirable to get intermediate speeds. The resistance
also prevents undue current at the moment of starting. The operation will be
similar to that above set forth when the lower section of the switch is utilized, but
as already indicated, this will drive the motor in the opposite direction.
It is to be noticed that, in the arrangement above described, there is never any
idle wire (that is, there are never idle coils) in the motor, and that each winding
will always carry its proper amount of current without danger of being burned out.
To more fully explain this method of regulation, let it be assumed that the motor
wound as shown in Figure 1 is a 24 kilo-watt machine wound for 500 volts and is
running at full speed, say 300 revolutions per minute, the switch being in the
position 4, the resistance of the motor circuit when one field-magnet and one
armature winding are in series and the two field-magnet and armature branches
are in multiple, being 1 ohm and the extra resistance R being 2.7 ohms. Con-
sequently, in the fourth position of the switch, we have a current of 48 amperes,
and a counter electro-motive force of 452 volts, since
48. As assumed,
this gives 300 revolutions. Moving the switch to the third position, we have a
current as before of 48 amperes, and a counter electro-motive force of 322 volts,
48 and the speed will be approximately 300 x = 213 revolu-
since
=
500 - e
1 +2.7
tions per minute.
500 ―e
322
452
Moving the switch to the second position, we have a current of 24 amperes, a
resistance of 4 ohms, and a counter electro-motive force of 404 volts, since
300
2
404
452
500-e
4
= 24
= 134 revolutions per minute, and
and the speed will be approximately
finally, with the switch in the first position we have a current of 24 amperes, a resist-
ance of 6-7 ohms, and a counter electro-motive force of 339 volts, since
and the speed will be approximately
300 339
2 452
=
500 -e
6.7
112 revolutions per minute.
=
24,
In Figure 2, a series motor is shown having four field magnet coils, 13, 13, 14, 14',
and four commutators, 2, 21, 3, 3', it being understood that each commutator is
connected to a separate armature coil as above explained, the several coils of the
field-magnet, and the several commutator brushes being connected to the switch-

page_text: brushes or contact devices 15, 16 &c. in the order shown. The incoming line is
connected to brush 19 through R to 15, and the outgoing line is connected to 20.
In connection with this form of motor, the switch is slightly different from that
above described. It has five different positions on each side of the open position,
as indicated by the numerals 1-51 and 1"-5". In this switch some of the contact
plates are connected by conductors, as indicated at 59. This is for the purpose of
enabling the switch to correctly change the order of arrangement or connection of
the several coils. It will be unnecessary to describe the circuits in detail, but by
tracing them out on the drawing it will be found that when the-switch is in
position 1 all the field-magnet and armature coils will be in series and the
resistance R will be out of circuit, and that the coils of the field-magnet and
armature alternate in the series so that the coils will come properly into circuit
when the connection is changed by the switch shown to series, multiple or multiple
series, but this particular order of coils is not essential. In the second position of
the switch, there will be a multiple series connection, there being two field-magnet
and two armature coils in each branch, and the resistance R being in the circuit.
In the third position of the switch, the connection will be the same, except that
resistance R will be cut out. When the switch is in the fourth position, all the
field-magnet coils will be in parallel and there will be one armature coil in series
with each field-magnet coil, and resistance R will be in circuit, while by the
following movement of the switch, resistance R will be cut out. This gives the
highest speed for which the motor is constructed, at the same time maintaining
the torque at its highest point. When the lower section of the switch is used, the
motor will be reversely driven, as heretofore described. This is a more perfect
form than that of Figure 1. owing to the larger number of coils, giving a larger
number of different speeds by commutating the coils without the resistance R.
The invention is not limited to a switch mechanism having just the arrangement
of contact plates &c. shown in the drawing, nor to any particular type of motor,
since these are details which can be largely varied.
When the motor to be governed is to be used in connection with a 3 wire or
similar supply system it will be connected as shown in Figures 3 and 4.
In Figure 3, 1, 2, 3 are the positive, negative and neutral conductors of a three-
wire supply system, and it is supposed in the present instance for illustration that
the difference in potential between the two outer wires 1, 2 is 220 volts, and the
difference between the central or neutral conductor and the outer conductors is
110 volts. 4. 5 are commutators of two independent coils forming a part of a single
armature of an electric motor, the field magnet coils of which are indicated at 6, 7.
The mechanical construction of this motor is not shown in detail, since it may be
of any suitable construction. The circles 8 to 17 inclusive represent switch
brushes or contact devices, which are adapted to co-operate with the contact plates
of a switch, the shape and relative arrangement of the plates which may be adopted
being indicated below the motor. In practice it will be preferable to employ a
snap-switch similar to that shown in Figures 5 to 11, and the row of contact
devices 8 to 17 will normally stand between the two series of contact plates on the
surface of the switch, so that by moving the switch in one direction the coils will
be connected up in one way, and when moved in the other direction the coils will
be connected up in the opposite way to reverse the motor. The plates should be
so placed on the switch that the switch contact plates will move relative to the
brushes or contact springs in the direction indicated by the arrows. The plates in
the upper section are numbered 18 to 25 inclusive, and several of the plates are
connected by wires as indicated at 26. The contact devices 8, 9, and 17 are
connected respectively to the positive, neutral, and negative supply wires as shown.
The brushes 10, 11, and 16, 17 are connected to the terminals of the field-magnet
coils, and the brushes 12, 13, 14, 15 are connected to the commutator brushes b.
When the switch is moved to bring the contact devices onto the contact plates,
in the first position of the switch indicated by the dotted line 1', the circuit will be
closed between the neutral conductor 3 and the negative conductor 2 through the

page_text: motor coils in series. Thus there is a potential of 110 volts on the motor. This
drives the motor at approximately one-quarter its full speed and, with its maximum
torque. When the switch is moved so that the contact devices occupy the position
indicated by line 21, the motor coils will be in series between the positive con-
ductor and negative 2, thus giving a potential of 220 volts and doubling the
speed, so that it will be one-half the full speed; and finally, when the switch is
moved so that the contact devices occupy the position indicated by line 3', the field
magnet coil 6 and armature coil 4 will be in series but will be in multiple arc with
the field-magnet coil 7 and armature coil 5, the motor being connected between the
two outer conductors 1, 2. This again doubles the speed, raising it to the highest
speed for which it is adapted to be used, without changing the torque. By tracing
out the connections, when the lower section of the switch is used, it will be clear
that the speed will be governed as above set forth, but that the circuit through the
armature coils will be in reverse direction, thereby causing the motor to turn in
the opposite direction. The second speed (i.e., the speed obtained with the switch
contacts on the line 2¹) can be obtained as well by applying the electro-motive
force between 3 and 2 to motor coils in multiple, instead of applying the electro-
motive force between 1, 2, to the motor coils in series. In other words, one half
the electro-motive force of the 3-wire system with motor coils in multiple equals
full electro-motive force of the 3-wire system with motor coils in series, and to
double the first speed, instead of leaving the motor coils in series and changing the
line connections, the line connections may be left the same and the motor coils
changed to multiple. While I have shown and specifically described a 3-wire
system, it is evident that the invention is equally applicable to similar compensating
systems having more than three wires carrying or adapted to carry different electro-
motive forces.
In Figure 4 the parts are numbered as far as possible to correspond with
numbers above given. In this modification the two field-magnet coils 6, 7 are
always in series with each other and may be considered as forming a single coil,
but by operation of the switch, the contact plates of which are shown below the
motor, the connections of these coils and of the armature coils will be so changed
that when the contacts are in the first position, indicated by the line 1', the field
magnet circuit only will be closed between conductors 3, 2. In the second position
of the switch, the two armature coils will be in series with each other and in
multiple are with the field magnet coils between the same two supply wires. In the
third position the field magnet coils will remain in the same branch between the
conductors 2, 3, and the armature coils will be in series with each other in another
branch between the conductors 1, 2; and finally, in the fourth position, the two
field-inagnet coils will remain in series between the conductors 3, 2, while the
armature coils will be in multiple arc with each other and will be connected
between the two outer conductors 1, 2 thus giving the highest speed for which the
motor is adapted, at the same time maintaining its torque constant. By connecting
the field-magnet coils between the wires 3, 2 to constantly energize the field-
magnet, I am enabled to use a coarser and shorter wire for the coils than would be
possible if these shunt field-magnet coils were connected between the two outer
wires 1, 2, and this is advantageous. In governing the motor, as described, no
artificial resistance is employed in starting the motor or in changing its speed.
The motor runs without heating at full speed any more than at slow speed and the
efficiency is practically the same at each speed.
Referring now to Figures 5 to 11, a form of snap switch will be described
adapted to vary the connection of the motor coils as above indicated. Said figures,
except Figure 9, show the mechanical construction of the switch. The diagram,
Figure 9, shows the switch plates developed, and the connection of a 3-wire circuit
to the switch, and to a motor having the same arrangement of coils as described in
connection with Figure 4. If the motors shown in Figures 1, and 3 were to be
governed by the switch, the arrangement of switch plates shown in those figures
would be used on the surface of the switch drum,

page_text: The main advantages of this switch are that it can be moved forward to com-
mutate the motor coils so as to drive the motor in one direction, or backward to
commutate the coils to drive the motor in a second direction, and in both cases the
circuits will be changed by a snap or spring action.
In Figure 5, 1 is an enclosing case in which are standards 2 supporting the shaft
or spindle 3, on which is the wood or other insulating cylinder 4 which is secured
to the spindle. On the surface of the insulating drum or cylinder are any suitable
number or arrangement of contact plates or devices. The form which is preferred
is that illustrated in the drawing, consisting of curved metal plates 5, provided
with vertical webs or flanges 6, the plates 5 being adapted to fit the surface of the
supporting body. As shown in Figure 9, these plates and their flanges are of
various lengths, in order that the circuits may be commutated in the desired order.
These flanged contact plates are arranged in parallel circumferential lines or rows,
which are interrupted at suitable points, and long gaps are avoided by putting in
idle plates of the same shape as those which are actually used as switch plates.
This causes the action of the switch to be more uniform, since the friction offered
by the contact springs will be the same whatever the position of the switch body,
and this would not be the case were the idle plates omitted. Below the cylinder
are co-operating contact springs 7, 8 (which correspond to the circles 8 to 17 of
Figure 4 and the circles 7 of Figure 9), the number depending on the arrangement
of circuits to be controlled. The springs or plates 7, are pivotted at their lower
ends, as indicated in Figure 6 and at their upper ends embrace the flanges 6, thus
electrically connecting the springs with said flanges. The devices to which the
springs 7, 8 are pivotted are provided with suitable binding screws for securing
the circuit wires thereto.
Referring to Figure 9, it will be seen that the central row of flanged plates are
entirely disconnected from each other and from all other plates on the switch.
Therefore, when the switch stands so that the springs 7, 8 make contact on a
median line, that is a line passing lengthwise of the cylinder through this row of
plates, the circuit with which the switch is connected is open. Several of the
plates at either side of the centre are shown connected by dotted lines 9, these lines
indicating conductors passing from one plate to the other preferably through
grooves 10 (see Figure 8) in the wooden drum.
Pivotted at 11 are two upright arms 12, 13,,carrying longitudinal bars or
strikers 14, 15 preferably of wood, extending by all of the springs or plates 7, 8.
A spring 16 connects these two pivotted arms and tends to hold them in the
position shown in Figure 6, that is, with one edge of each bearing against the
springs 7, 8. The arms 12, 13 when in the position shown in Figure 6 bear
against any suitable stop, for example, flanges 17, so that the spring cannot,
under any circumstances, move said parts further in the direction of said flanges than
shown. Carried by these arms are lugs 18, to which are pivotted detent, trip or
releasing levers or devices 19, 20, the inclination or position of which can be
readily and delicately adjusted by means of screws 21 or similar devices. The
adjacent ends of the two devices 19, 20 span the corrugated or scalloped ring 22,
at the centre of the drum 4, and rest at either side of one of the transverse
pins 23 carried thereby. Pivotted at 24, 25 are arms 26, 27, carrying at their
upper ends rollers 28, 29, adapted to rest in the depressions of the scalloped
ring 22, and to ride over the elevated portions thereof, and constituting centering
devices adapted to bring the movable body or member of the switch to rest
with the several successive points of contact exactly in line with the springs 7, 8
as the switch is successively moved.
The levers 26, 27 are provided with springs 30 tending to hold them in the
position shown. The switch may be operated by means of any suitable handle,
but preferably by one allowing lost or independent motion. In Figure 5, such
a handle is shown and consists of a sleeve 31, adapted to fit the spindle 3, and
having a cut-away portion 32 of considerably greater width than the rib or pro-
jection 33 on the spindle, and having an arm 34 provided with a handle 35:"

page_text: The operation of the switch described is as follows:
When the handle is placed on the spindle and turned, for example, toward the
right, the pin 231 will be carried toward the left and will carry before it the
device 20 and the strip 15, tilting the arm 13 on its pivot and putting the spring 16.
under increased tension. As the switch drum is turned by the handle, the upper
ends of the springs 7, 8 will move along with the plates on the drum, being
carried along by the friction due to the force with which they grasp the flanges 6.
At the same time the wheels 28, 29 will be forced back by the elevated portions
of the scalloped ring, thus compressing springs 30.
When the switch drum has
been moved a certain distance, it will be evident that the pin 23¹ will be released.
by, or will slip off from, the end of the device 20, thus allowing the spring 16 to
contract, carrying the strip 15 suddenly back against the springs 7, 8, forcing
them off from the flanges 6, to which they are at that time connected, and carrying
them suddenly along onto the next succeeding contact line of the flanges indicated
by the dotted line marked 1st in Figure 9, thus giving an instantaneous closure
of the circuit. If the switch drum be turned further, the, same movement would
be repeated, the, switch contacts being instantaneously moved from the first contact
position to the succeeding one, marked 2nd and so on. When the switch is
returned to its normal or open position, that is, when it is moved toward the left,
each change of circuit connections will be made by the spring action as in the
forward movement. The. parts are so proportioned that the rounded elevated.
portions of the ring 22 are carried by the wheels 28, 29, so that the latter press
against the ring beyond the dead centre just at the moment, that the pins 23 are
released. In this manner, the springs 30 co-act with spring 16 to throw the.
contacts. The main object, however of the wheels 28, 29 and the springs 30 is to
ensure the stoppage of the drum so that the line of contact on the drum shall be
exactly in line, with the springs,7, 8 when, the drum comes to rest.. The handle..
by means of which the drum is moved, as already indicated, is constructed to allow
an independent or lost motion between it and the drum spindle, so that when the
spring acts it is free to move the drum independently of the handle...
וי
In Figure 9 is shown a 3-wire circuit, a motor, having two armature coils A, A'.
with separate commutators; a shunt field-magnet F, M and contact devices repre-...
sented by the circles 7 and corresponding to the contact springs 7, 8 of Figure 5,
these contact devices being connected to the positivé, negative and neutral wires of
the circuit and to the motor coils, as shown. By tracing the circuits closed by the
switch as it is moved; it will be found that when the switch is in position so that
contact is made on the line marked "1st" with the devices 7, the field-magnet
circuit only is closed, the contact plates 5, 5" serving to connect the two lower
contact devices 7...
In the second position of the switch, the plates 5', 5, 51, 5, 5 and 5 are
brought into operation and connect the two armature coils in series between the
positive and neutral mains, at the same time maintaining the field-magnet circuit
closed. In the third position of the switch, the two armature coils will be in series
between the positive and negative mains; while in the fourth position of the switch,
said coils will be in multiple arc between the same conductors.
Suppose that when the switch was in its normal or open position, it had been
desired to close the circuit by means of the contacts on the opposite side of the
central line. In this case, the handle would have been turned toward the left,
carrying the pin 23¹ toward the right and acting on the device 19, arm 12, strip 14,
spring 16 &c., in exactly the same manner as already described in connection with
he devices on the other side.
While a single spring is shown connecting the pivotted arms 12, 13, it is evident
hat each arm may have a separate spring, one end of which is secured to a suitable
ixed part of the apparatus.
It is also evident that the switch may be used without employing the spring press
ollers 28, 29 although its operation would be less perfect, and that the arrangement
of contact plates on the drum which has been indicated is merely illustrative, and

page_text: that the invention is not confined to this arrangement or to any particular number
of contact plates or springs. While it is preferred to have the contact plates pro-
vided with vertical flanges, on the sides of which the co-operating springs make
contact, this is not essential.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
彝
'
1. The method of regulating the speed of an electric motor which consists in
varying both the series and multiple arc relation of its armature coils and the series
and multiple arc relation of its field-magnet coils, substantially as set forth.
2. An electric motor having its armature and field-magnet each wound with
independent sections of coils, in combination with circuit changing devices for varying
the series and multiple arc relation of the armature coils and circuit changing
devices for varying the series and multiple arc relation of the field-magnet coils,
substantially as set forth.
: 3: An electric motor having its armature and field-magnet each wound with
independent sections of coils, in combination with a resistance in the motor circuit,
circuit changing devices for varying the series and multiple arc relation of the
armature coils, circuit changing devices for varying the series and multiple arc
relation of the field-magnet coils, and circuit changing devices for cutting said
resistance in and out of circuit, substantially as set forth.
4. Governing electric motors connected to 2-wire, 3-wire or other circuits by
varying the connection of the motor coils in the manner described.
5. A switch, preferably movable forward and backward, having one or more
springs for throwing one switch member, and one or more springs for throwing the
co-operating switch member, whereby a double snap action is obtained.
6. A switch for varying the connection of motor coils and for other purposes and
having a body carrying contacts, a handle for moving the body, a spring for
throwing the movable body when it has been started by the handle, the switch
having also switch springs or arms and a spring or springs adapted to act on said
arms.
1
'