Aug. 19, 1947.
2,426,071
c. e. VEINOTT
ALTERNATING-CURRENT MOTOR SYSTEM
Fil'ed Oct. 23, 1943
32 ‘I;
.C 040. mVWeMmmy)rlw
mWm
7- I
ATTORNEY
Patented Aug. 19, 1947
2,426,071
UNITED. STATES PATENT OFFICE
2,426,071
ALTERNATING-CUBRENT MOTOR SYSTEM
'Cyril G. Veinott, Lima, Ohio, assignor to West‘
ingh‘ous'e Electric Corporation, East Pittsburgh,
Pa, a corporation of Pennsylvania
Application October 28, 1943, Serial No. 508,055
13 Claims. (Cl. 192—.02)
1
2
The present invention relates to ‘alternating
thin of the motor and the operation ‘of the brake
and clutch are controlled by direct-‘current
current motors provided with a brake and con
nected to the load either directly or by means of
a clutch, and it relates, more particularly, to con~
troll means for such motors.’
There are numerous applications for electric
solenoids.
A further object ‘of the invention is to provide
an alternating-current motor having a brake and
clutch in Which the brake is released and the
be stopped as soon as the motor is de'e’nergized and
clutch engaged by means of solenoids-energized by
direct current when the motor is ‘started, and in
must be vpositively held in position.
which means are provided ror positively prevent‘
motors in which the load, ‘or driven device, must
One such
i‘ng release ‘of the brake and engagement of the
clutch in case or failure or ‘the alternating-‘current
application is in the case of motors used on air
craft. Many ‘of the loads driven by aircraft
motors, ‘such as ‘control surfaces, must be accur—
ately ‘stopped at a desired point in ‘their move
ment, and must be positively held in position.
Brakes are used for this purpose, and in many
cases the motor is connected to the load by
supply to the motor.
‘
Still another Object or the invention ‘is to pro
Vide an alternating-current motor having a brake
and clutch in which thermally-responsive pro‘
tective means are provided in the ‘motor for ‘de
energizing the motor and causing the brake to be
means of ya clutch which is disengaged as soon
applied and the ‘clutch disengaged ‘in response to
as the motor is de'en'erg'i‘zed in order to permit
excessive heating or the motor.
more rapid stopping of the driven device espe
cially where most of the rotational inertia is in 20 The invention will be more fully understood
from the following detailed description, taken in
the motor armature.
connection with the accompanying drawing, in
In such motor systems, the brake is released
which:
_
and the clutch engaged only while the motor is
Figure 1 is a schematic v'liring diagram showing
running, and the brake and clutch are operated
by means of solenoids. When direct-current 25 one embodiment of the invention; and
Figs. 2, 3, and 4 are similar diagrams showing
motors are used, the design of such a system pre-v
other embodiments of the invention.
sents no particular diiiiculties since the brake
Fig. 1 shows an alternating-current motor I‘,
and clutch solenoids can be energized directly
which has been shown as a. three-phase motor
from the motor circuit; If alternating-current
motors arev used, however, ‘such a simple arrange- 30 of- any suitable type, although the invention is
also applicable to other, types or motors, such as
ment is not so satisfactory because of the ‘greater
single-phase motors. The motor I is supplied
weight of alternating-current solenoids, espe
from a three~phase supply line 2, and a contactor
cially at the relatively high vfrequencies, such as
3 ‘is provided for controlling the cner'giz'au'on or
400 cycles, ‘used in alternating-current systems on
the motor. The co‘zita'c’tor 3 has ‘a, plurality __cr
aircraft. For example, a ‘NO-cycle alternating
contacts 4 connected between the motor I and
current vsolenoid Weighs about three times as
the line 2 and has an ‘operating c011 5 arranged so
that when the‘ coil 5 is energized, the ccntactor
perform the same function. This increase in
3 closes its contacts to connect the‘ motor to the
Weight is extremely undesirable in aircraft equip
ment, and in many cases is not permissible.
40 line. ‘The motor i is connected to the load which
it drives by means of a clutch '6, which may be of
The principal object of the present invention
any suitable type, and which is arranged so that
is to provide an alternating-current motor for
it is normally held in the disengaged position, as
aircraft use provided with a brake and clutch in
by a spring or other. suitable means. The ‘clutch
which the brake is applied and the cluteh disen
much as a direct-current solenoid designed to
6 has an Operating‘ coil or solenoid 1 which moves
the clutch to the engaged position when the doll
‘l is energized, so as to connect the motor to the
was. A brake s is also provided which is dis
gaged immediately upon deenergi'zation of the
motor, and the brake is released and the clutch
engaged when the motor is started, and
which
the brake and clutch are actuated by di’r'ecte
current solenoids,v so that relatively light-weight
solenoids can be used.
50
Another object of the invention is to provide
tion, as by means of a spring 9,- and is provided
with an Operating can or solenoid 10 which re;
leases the brake when it is energized.
an alternating-current motor for aircraft use
having a brake arid a clutch in which the brake
is released and the clutch engaged only during op
eration of the motor, and in which the energiza
posed to prevent rotation of the load when the‘
brake is applied. vAs shown diagrammatically,
the brake is normally maintained in braking posi-_
55
The operating coil 5 of the contacto‘r 3,- the
2,426,071
clutch operating coil ‘I, and the brake operating
coil II] are all energized from
source of direct
current, which is indicated
a direct-current
bus II. The bus II represents any source of
direct current which is available on the airplane,
and is shown as being supplied from a source
of direct current, such as a battery
one term~
inal of which is connected to the bus II, and the
4
brake 8 to be released so that the motor can drive
the load. When the switch I4 is opened to stop
the motor, all three operating coils are immedi
ately deenergized,
the contactor 3 drops out
to disconnect the motor from the line. Substan
tially simultaneously, the clutch 5 returns to its
disengaged position, and the brake 8 is applied so
that the load is immediately stopped and held in
other terminal grounded at I3.
The operating
position.
i
coils 5, 1, and II] are connected in series to the 10
If a failure of the alternating~current supply
bus II through a control switch Ill, which may be
to the motor I should occur, the resulting ab
either manually or automatically operated.
sence of voltage on the relay coil 29 will cause
The series circuit comprising the operating
the relay IE to drop out and open its contact IS,
coils also includes a thermally-responsive pro
interrupting the circuit to the brake and clutch
tective device I 5 mounted in any suitable position
operating coils Id
7. Thus, these coils can
in or on the motor I so as to be responsive to
not be energized and the clutch remains disen
excessive heating of the motor resulting from
gaged and the brake applied whether the switch
overload or any other cause.
The thermally
III is open or closed.
In case of excessive heating
responsive device I 5 has normally closed con
of the motor during operation, as a result of
tacts I6, and it is adapted to open these contacts
overloading or any other cause, the thermally
in response to excessive heating of the motor.
responsive device I5 is actuated to open its con
The contacts I6 of the protective device I5 are
tacts IE5, interrupting the circuit to the operating
connected in series with the brake and clutch
coils in the same manner and causing the motor
operating coils I0 and ‘I, and are connected to
I to be deenergized, the clutch disengaged, and
ground at I‘! to complete the energizing circuit 25 the brake 8 applied.
for the operating coils.
will be apparent,
Thus, a relatively simple control system is pro
therefore, that when the control switch III is
vided which permits the use of direct-current
closed, the operating coils 5, ‘I, and iii will all be
solenoids to control the brake and clutch asso
ciated with an alternating~current motor, so that
released
simultaneously
and theenergized,
clutch engaged
and the
while
brake
the will
motor
30 relatively light-weight solenoids can be used. In
is simultaneously connected to the line 2, thus
some cases, the clutch 8 is not necessary and may
permitting the motor to drive the load.
be omitted, and it will be apparent that the omis
sion of the clutch does not affect the operation
clutch
Since6, the
and operating
brake 8 arecoils
energized
for thefrom
contactor
a direct
of the system. Similarly, the voltage-responsive
current source which is independent of the alter-
hating-current supply to the motor, it would be
possible, in case of failure of the alternating-cur
rent supply, for the clutch to be engaged and the
brake released, but the motor not energize-cl.
This would be a very undesirable condition, and
in the case of certain types of driven devices on
an airplane might be dangerous. In order to
prevent the occurrence of such a condition, a
voltage-responsive relay It is provided. The re
lay I8 has a contact I9, which is connected in the
series circuit with the operating coils 5, ‘I, and
I0, and has an operating coil 26 which is actu
ated in response to the voltage applied to the
motor I. In the particular embodiment shown
in the drawing, the coil 26 is supplied from a
three-phase bridge-type recti?er 2| which is con
nected across the three-phase supply to the mo~
tor I. Such a recti?er and relay combination
can be designed to cause the relay It to drop out
and open its contact I9 either in response to a
failure of all three phases of the alternating-cur~
rent supply, or in response to a failure of only one
phase, as desired.
In the operation of this svstein, when the motor
is deenergized and at rest, and the coils ‘I and
I I] are also deenergized, the clutch t‘ is disen
gaged and the brake 8 is applied so that the load
is positively held against movement. When it
is desired to drive the load, the control switch Ill
is closed. If the alternating-current supply line
2 is energized so that a voltage is applied to the
recti?er 2|, the relay I8 has its contact It‘ closed,
and closing of the control switch Eli completes a
series circuit from the direct-current bus II
relay I8 may be omitted in some cases, although
it is usually desirable, and is often necessary, to
include it in the system in order to prevent
random movement of the load in case of failure
of the alternating~current supply to the motor.
Fig. 2 shows a somewhat different embodiment
of the invention which has certain advantages in
many cases. In this embodiment, the motor I,
clutch Ii, and brake 8 are similar to those shown
in Fig. 1, and the motor is connected to the sup
ply line 2 through the contactor 3 in the same
manner as described above.
In this case, how
ever, the operating coil 5 of the contactor 3 is
connected directly to the thermally-responsive
device I5, while the clutch operating coil 1 and
brake operating coil I 0 are connected in a sep
arate branch of the circuit in parallel with the
coil 5. The contact I9 of the voltage-responsive
relay I8 is preferably connected in series with the
clutch and brake operating coils ‘I and I0. It
will be apparent that the operation of this form
of the invention is substantially the same as that
described above. Thus, closure of the control
switch I4 effects simultaneous energization of the
operating coils 5, "I, and III to connect the motor
60 to the line and to cause engagement of the clutch
and release of the brake substantially simultane
ously with the starting ,of the motor. Opening
of the relay contact IS in response to failure of the
alternating-current supply, and opening of the
contacts of the thermally responsive device I5 in
response to overheating of the motor, effect dis
engagement of the clutch and application of
the brake in the same manner as described above.
Operation of the protective device I5, of course,
through the operating coils 5, Iii, and ‘I and the 70 also eifects deenergization of the motor.
protective device I5 to ground. Energ'zation of
The embodiment of the invention shown in Fig.
the coil 5 causes the contactor 3 to close its con~
2 has the advantage that the voltage relay I8
tacts 4, connecting the motor'I to the line, and
can be placed close to the motor I to afford pro
the simultaneous energization of the coils ‘I and
tection in case of failure of the alternating-cur
I0 causes the clutch 6 to be engaged and the 75 rent leads between the contactor 3 and the motor
arse-m1
5
6
I, since the recti?er 21 can be connected on the
direct-current bus ill. The motor is started by
motor side of the contactor 3. This may be an
important advantage in cases where ‘the motor
is placed at .a distance from the contactor. The
means of a normally open push-‘button 35. When
the push-button 35 is moved to closed position,
the coil 34 is connected to the direct-current bus
embodiment of Fig. 2 also has another advantage
ii, and the series circuit including the coil 34,
the coils l and Iii, and the protective device 15
in that the coil 5 of the contactor 3 can be a
standard coil designed for operation on the stand
ard direct-current voltage of aircraft systems
is energized.
The clutch is thus moved to en
gaged position, and the brake is ‘released, and at
the same time, the contactor 3| closes its con
since it is not connected in series with the clutch
and brake coils, as in Fig. l but is directly across 10 tacts 32 to connect the motor I to the line so that
it starts. The contact 33 of the contactor-3| is
the direct-current supply. The same advantage
also closed at the same time and completes a
applies to the clutch and brake coils which can
holding circuit bypassing the push-button 35, so
also be designed for the standard voltage without
that it may be released as soon as the contactor
regard to the design of the contactor coil.
Fig. 3 shows another form of the invention in 15 has closed.
The motor is stopped by actuating the nor
which the clutch and brake coils are controlled
mally closed push-button 3b, which interrupts
by ‘an additional contact on the motor contactor.
the circuit to the coils 34, ‘I, and I0, and thus
As shown in the drawing, the motor I is con
causes the contactor 3! to drop out, the clutch 6
trolled by a contactor 25 having an operating coil
26. The contactor 25 has three contacts 27 for 20 to be disengaged and the brake 8 applied. The
operation of the protective device IE to cause
connecting the motor I to the three-phase line
stopping or" the motor, disengagement ‘of the
2, and has an additional contact 28 which is con
clutch and application of the brake is the same
nected in series with the clutch operating coil
as described above in connection with the other
‘I and brake operating coil It]. The clutch and
brake coils ‘I and I0 are energized directly from 25 embodiments of the invention, and, if desired, a
voltage relay can be used to provide protection
the direct-current bus II and are connected
through the thermally-responsive device 55 of
against failure of the alternating-current supply.
The voltage relay in this case would have to be
connected in the manner shown in Fig. l on the
tactor operating coil '26 is connected to the direct
current bus II by means of a control switch 39, 30 line side of the contactor (H with its contacts
connected in series with the coil 34.
and the other end of the coil 26 is connected to the
t should now be apparent that a control
protective device I5, so that the coil 26 is in
system has been provided for an alternating
parallel with the clutch and brake coils "I and Iii.
current aircraft motor provided with clutch and
When the control switch 3% is closed, either
manually or automatically, the coil 2% is en 35 brake in which the operation of the clutch ‘and
brake and the energization of the motor itself
ergized and causes the contactor 25 to close its
are controlled by means of direct-current sole
contacts 21 and 28. Closure of the contacts
noids,
so that smaller and lighter solenoids can
21 connects the motor I to the line 2 to start
be used than would be possible with alternating
it in operation, while closure of the contact 28
current control; It will also be apparent that
connects the coils l and ID to the direct-current
various modifications may be made without de~
bus I I to cause the clutch B to be engaged and the
parting from the spirit of the invention, and that
brake 8 to be released, thus permitting the motor
the invention may be applied to motors and asso
to drive the load. It will be apparent that the
ciated devices of various kinds. Thus, in some
thermally-responsive protective device I5 oper
45 cases the clutch 6 may be omitted, and the motor
ates in the same manner as in the previously
connected directly to the load, with the brake 8
described embodiments of the invention to cause
being used alone to stop the rotation of the load
deenergization of the motor and of the clutch
and motor. Similarly, in some cases the brake
and brake coils in response to excessive heating
and clutch may be combined into a single device,
of the motor.
and a single solenoid used for operation of both
If desired, a voltage-responsive relay similar
the brake and clutch. Where two coils are used
to the relay I8 shown in Figs. 1 and 2 may be
to control the clutch and brake, as shown in the
. used with‘ this embodiment of the invention with
drawing, they may be connected to each other in
its contact connected in series in the circuit
series, as shown, or in parallel without affecting
of the brake and clutch operating coils so as to
the operation of the system.
interrupt the circuit of the coils ‘I and id in re
It is to be understood, therefore, that although
sponse to failure of the alternating-current sup
certain speci?c embodiments of the invention
ply. Thus, this embodiment of the invention is
have been shown for the purpose of illustration, it
essentially similar to those previously described
is not limited to these speci?c arrangements, but
but differs in that the brake and clutch coils are
in its broadest aspects it includes all equivalent
controlled by an additional contact on the motor
the motor to ground at 29. One end of the con
modi?cations and embodiments which come
within the scope of the appended claims.
I claim as my invention:
‘sediments of Figs. 1 and 2.
1. In combination, an alternating-current elec
Fig. 4 shows a further embodiment of the 65
tric motor, means for connecting said motor to a
invention which is arranged for push-button
load, braking means for stopping rotation of the
control of the motor. In this ?gure, the motor
contactor, so that a contactor must be used hav
ing One more contact than those used in the em“
1 is connected to the line by a contactor 3!,
which may be similar to the contactor 25, and
which has contacts 32 for connecting the motor
load, said braking means being normally main
tained in braking condition, a brake operating
coil for releasing said braking means to permit
to the line 2 and an additional holding contact
33. The contactor (H has an operating coil 34
which is connected in series with the clutch and
for connecting the motor to a source of alter-nat
brake coils ‘I and I0 and the protective device I5,
and which is adapted to be energized from the
of said contact means, means for energizing said
operating coils from a source of direct current
the load to be driven by the motor, contact means ~
ing current, an operating cell for effecting closing
2,426,071
7
which is substantially independent of the alter
nating-current supply to the motor, and means
for preventing energization of at least said brake
operating coil in case of failure of the alternating
current supply to the motor.
2. In combination, an alternating current elec
tric motor, clutch means for connecting said
motor to a load, said clutch means being nor
mally disengaged, a clutch operating coil for
effecting engagement of the clutch means, brak
ing means for stopping rotation of the load, said
braking means being normally maintained in
braking condition, a brake operating coil for
releasing said braking means to permit the load
8
current supply to the motor, said protective
means being adapted to effect deenergization of
the control circuit in response to excessive heat
ing of the motor, and means for preventing en
ergization of at least said brake operating coil
in case of failure of the alternating-current
supply to the motor.
6. In combination, an alternating-current elec
tric motor, clutch means for connecting said
10 motor to a load, said clutch means being normally
disengaged, a clutch operating coil for effecting
engagement of the clutch means, braking means
for stopping rotation of the load, said braking
means being normally maintained in braking
to be driven by the motor, contact means for 15 condition, a brake operating coil for releasing said
connecting the motor to a source of alternating
braking means to permit the load to be driven
current, an operating coil for effecting closing of
by the motor, contact means for connecting the
said contact means, means for energizing said
motor to a source of alternating current, an op
operating coils from a source of direct current
erating coil for effecting closing of said contact
which is substantially independent of the alter 20 means, thermally~responsive protective means
mating-current supply to the motor, and means
associated With the motor, said operating coils
for preventing energization of at least said clutch
and thermally-responsive protective means being
and brake operating coils in case of failure of
connected in a control circuit, and means for
the alternating current supply to the motor.
energizing said control circuit from a source of
3. In combination, an alternating-current elec 25 direct current, said protective means being
tric motor, means for connecting said motor to
adapted to effect deenergization of the control
a load, braking means for stopping rotation of
circuit in response to excessive heating of the
the load, said braking means being normally
motor.
maintained in braking condition, a brake operat
'7. In combination, an alternating-current elec
ing coil for releasing said braking means to per
tric motor, clutch means for connecting said
mit the load to be driven by the motor, contact
motor to a load, said clutch means being nor
means for connecting the motor to a source of
mally disengaged, a clutch operating coil for ef
alternating current, an operating coil for effecting
fe'cting engagement of the clutch means, braking
closing of said contact means, said operating coils
means for stopping rotation of the load, said
being connected in a circuit, means for ener 35 braking means being normally maintained in
gizing said circuit from a source of direct cur
braking condition, a brake operating coil for re
rent which is substantially independent of the
leasing said braking means to permit the load
alternating-current supply to the motor, and
to be driven ‘by the motor, contact means for
means responsive to the voltage applied to the
connecting the motor to a source of alternating
motor for controlling the energization of said 40 current, an operating coil for effecting closing of
circuit.
said contact means, thermally-responsive protec
4. In combination, an alternating-current elec~
tric motor, means for connecting said motor to
a load, braking means for stopping rotation of the
tive means associated with the motor, said oper
load, said braking means being normally main
tained in braking condition, a brake operating
coil for releasing said braking means to permit
ating coils and thermally-responsive protective
means being connected in a control circuit, means
‘for energizing said control circuit from a source
of direct current which is substantially inde
the load to be driven by the motor, contact means
pendent of the alternating~current supply to the
motor, said protective means being adapted to
‘for connecting the motor to a source of alter
effect deenergization of the control circuit in re
nating current, an operating coil for effecting 50 sponse to excessive heating of the motor, and
closing of said contact means, thermally-respon
means for preventing energization of at least
sive protective means associated With the motor,
said clutch and brake operating coils in case of
said operating coils and thermally-responsive
failure of the alternating-current supply to the
protective means being connected in a control
circuit, and means for energizing said control
circuit from a source of direct current, said pro
motor.
8. In combination, an alternating»current elec
tric motor, means for connecting said motor to
a load, braking means for stopping rotation of
tective means being adapted to effect deenergiza
tion of the control circuit in response to excessive
the load, said braking means being normally
heating of the motor.
maintained in braking condition, a brake operat
5. In combination, an alternating-current elec 60 ing coil for releasing said braking means to permit
tric motor, means for connecting said motor to
the load to be driven by the motor, contact means
a load, braking means for stopping rotation of
for connecting the motor to a source of alter
the load, said braking means being normally
nating current, an operating coil for effecting
maintained in braking condition, a brake oper
closing of said contact means, said operating coils
ating coil for releasing said braking means to 65 being connected in series, means for energizing
permit the load to be driven by the motor, con
the series circuit comprising said operating coils
tact means for connecting the motor to a source
from a source of direct current which is substan
of alternating current, an operating coil for ef
tially independent of the alternatingmurrent sup
fecting closing of said contact means, thermally
ply to the motor, and means for interrupting
responsive protective means associated with the
said circuit in response to failure of the alter
motor, said operating coils and thermally-respon
nating-current supply to the motor.
sive protective means being connected in a con
9. In combination, an alternating-current elec
trol circuit, means for energizing said control
tric motor, clutch means for connecting said
circuit from a source of direct current which
motor to a load, said clutch means being normally
is substantially independent of the alternating 75 disengaged, a clutch operating coil for effecting
Ma
2,426,071
10
engagement of the clutch means, braking means
electric motor, means for connecting said motor
to a load, braking means for stopping rotation
of the load, said braking means being normally
means being normally maintained in braking
maintained in braking condition, a brake oper
condition, a brake operating coil for releasing
ating coil for releasing said braking means to
said braking means to permit the load to be
permit the load to be driven by the motor, a
driven by the motor, contact means for connect
contactor having a plurality of contacts for con
ing the motor to a source of alternating current,
necting said motor to a source of alternating
an operating coil for e?‘ecting closing of said
current, a contactor operating coil for effecting
contact means, said operating coils being con
nected in series, means for energizing the series 10 closing of said contacts, an additional contact
on said contactor operable With the ?rst-men
circuit comprising said operating coils from a
tioned contacts, said additional contact being
source of direct current which is substantially
connected in series with said brake operating
independent of the alternating-current supply
coil for connecting the brake operating coil to a
to the motor, and means for interrupting said
circuit in response to failure of the alternating 15 source of direct current to be energized thereby,
and means for connecting said contactor operat~
current supply to the motor.
ing coil to said source of direct current.
10. In combination, an alternating-current
13. In combination, an alternating-current
electric motor, means for connecting said motor
electric motor, clutch means for connecting said
to a load, braking means for stopping rotation of
the load, said braking means being normally 20 motor to a load, said clutch means being normally
disengaged, a clutch operating cell for effecting
maintained in braking condition, a brake oper
engagement of the clutch means, braking means
ating coil for releasing said braking means to
for stopping rotation of the load, said braking
permit the load to be driven by the motor, con
means being normally maintained in braking con
tact means for connecting the motor to a source
of alternating current, an operating coil for ef 25 dition, a brake operating coil for releasing said
braking means to permit the load to be driven
footing closing of said contact means, said oper
by the motor, a contactor having a plurality of
ating coils being connected in parallel, means
, for stopping rotation of the load, said braking
for energizing said operating coils from a source
contacts for connecting said motor to a source
01f alternating current, ‘*a contactor operating
of direct current which is substantially inde
pendent of the alternating-current supply to the 30 coil for effecting closing of said contacts, an
additional contact on said contactor operable with
motor, and means for interrupting the circuit
the ?rst-mentioned contacts, said additional con
of at least said brake operating coil in response
tact being connected in series with said clutch
to failure of the alternating-current supply to
and brake operating coils for connecting the
the motor.
11. In combination, an alternating-current 35 clutch and brake operating coils to a source of
direct current, and means for connecting said
electric motor, clutch means for connecting said
contactor operating coil to said source of direct
motor to a load, said clutch means being nor
current.
mally disengaged, a clutch operating coil for
CYRIL G. VEINOTT.
e?ecting engagement of the clutch means, brak
ing means for stopping rotation of the load, said
REFERENCES CITED
braking means being normally maintained in
braking condition, a brake operating coil for
The following references are of record in the
releasing said braking means to permit the load
?le of this patent:
to be driven by the motor, contact means for
UNITED STATES PATENTS
connecting the motor to a source of alternating 45
current, an operating coil for effecting closing
of said contact means, said clutch and brake
operating coils being connected in series, and said
contact means operating coil being connected
in parallel with the clutch and brake operating 50
coils, means for energizing said operating coils
from a source of direct current which is substan
tially independent of the alternating-current sup
ply to the motor, and means for interrupting the
circuit of at least the clutch and brake operating 55
coils in response to failure of the alternating
current supply to the motor.
12. In combination, an alternating-current
Number
Name
Date
749,439
Ihlder ___________ __ Jan. 12, 1904
1,547,382
Gourdier et a1 _____ __ July 28, 1925
1,577,068
1,664,089
1,993,413
2,018,720
2,034,708
2,042,937
2,254,029
2,314,019
2,334,965
Oberschmidt _____ __ Mar. 16,
Ringwald _________ __ Mar. 27,
Mellon ____________ __ Mar. 5,
I-Iodgson _________ __ Oct. 29,
Browne et al ______ __ Mar. 24,
Henricksen _______ __ June 2,
Chladek et a1 _____ __ Aug. 26,
Shaw ____________ __ Mar. 16,
Thacker _________ __ Nov. 23,
1926
1928
1935
1935
1936
1936
1941
1943
1943