Improvements in or relating to "Starting Boxes" or Combined Rheostats and Automatic Cut-outs for Electric Motors.
Year: 1898

page_text: Improvements in or relating to "Starting Boxes" or Combined
Rheostats and Automatic Cut-outs for Electric Motors.
A communication from FRANK E. HERDMAN, Mechanical Engineer, residing at
Winnetka, Cook County, Illinois, United States of America.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, do hereby declare the nature of this invention to be as
follows:
This invention relates to starting boxes so-called, or to combined rheostats and
automatic cut-outs for electric motors.
Its main objects are by a single manipulation to first close the main or outside
circuit, and then gradually and automatically cut out the starting resistance
from the armature circuit of the motor; to automatically break or open the circuit
whenever the current passing through the motor ceases or is reduced in strength
to a certain limit, and to prevent the closing of the circuit until all the starting
resistance has been cut into circuit; to automatically break the circuit whenever
the current is increased to a certain degree of strength above the normal which
can pass through the motor without injury thereto; and to automatically cut
the starting resistance into the armature circuit whenever the circuit is broken,
either by cessation, abnormal fall or abnormal increase of current.
The device comprises a main switch for manually opening and closing the
main or outside circuit; a rheostat consisting of a series of fixed contacts con-
nected in series by suitable resistance, and of a movable brush or contact arranged
to traverse the fixed contacts and gradually cut out the resistance from the
armature circuit of the motor; an under-load magnet for holding the main switch
closed, and the movable contact or brush of the rheostat in position to exclude
all the resistance from the armature circuit while the normal current passes
through the motor; and an over-load magnet for short-circuiting or de-energizing
the under-load magnet, and thus allowing the main switch to open and break
the circuit whenever an abnormal increase of current passes through said over-
load magnet.
The main switch has a spring connection with the movable contact of the
rheostat, which tends, when the main switch is closed, to move said contact to
cut out the starting resistance from the armature circuit of the motor, and also
to automatically open the main switch when the under-load magnet, which
under normal conditions holds it closed, is de-energized.
The under-load magnet operates when energized through a pivoted catch to
hold the main switch closed, and this catch has an arm or detent which, when
said magnet is de-energized and all the resistance is in the armature circuit,
engages wth the movable contact of the rheostat and prevents it from moving to
cut out the resistance until the main switch is closed, the closing of the main
switch and the energizing of said magnet operating to disengage the arm
Di. 037

page_text: or detent from said movable contact. Said catch is also constructed and arranged
to prevent the closing of the main switch except when the movable contact of
the rheostat is in position to include all the starting resistance in the armature
circuit, so that after the main switch has been opened and the circuit broken, it
cannot be closed again until all the starting resistance is cut into circuit.
Dated thin 95th day of April 1802
BOULT & WADE,
Agents for the Applicant.
Improvements in or relating to "Starting Boxes" or Combined
Rheostats and Automatic Cut-outs for Electric Motors.
A communication from FRANK ELMER HERDMAN, Mechanical Engineer, residing
at Winnetka, Cook County, Illinois, United States of America.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, 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:-
This invention relates to starting boxes and automatic cut-outs for electric
motors.
Its main objects are by a single manipulation to first close the main or outside
circuit and then gradually and automatically cut out the starting resistance
from the armature circuit of the motor; to automatically break or open the circuit
whenever the current passing through the motor ceases or is reduced in strength
to a certain limit, and to prevent the closing of the circuit until all the starting
resistance has been again cut into the armature circuit; to automatically break
the circuit whenever the current is increased to a certain extent above the normal
strength which the armature of the motor is designed to carry; and to automati-
cally cut the starting resistance into the armature circuit whenever the circuit
is broken either by cessation, abnormal fall or abnormal increase of current.
The invention consists generally in the combination of a main switch for
manually opening and closing the main or outside circuit, a rheostat comprising
a series of fixed contacts connected in series by suitable resistance, and a movable
brush or contact adapted to gradually cut out the resistance from the armature
circuit of the motor when the main switch is closed, and to cut in said resistance
when said switch is opened; an under-load or cut-out magnet for holding the
main switch closed and the movable brush or contact of the rheostat in position
to exclude all the resistance from the armature circuit while the normal current
passes through the motor; and an over-load or releasing magnet for short-
circuiting or de-energizing the under-load magnet and thus allowing the main
switch to open and break the circuit whenever an abnormal increase of current
takes place in said over-load magnet.
In the accompanying drawings like letters designate the same parts in both
figures.
Fig. 1 is a vertical section of a starting box and automatic cut-out embodying
the invention, and Fig. 2 is a front elevation of the same, the circuit connections
and resistance coils of the rheostat being indicated diagrammatically by broken or
dotted lines.
A designates the main switch which may be, as shown in the drawing, an

page_text: ordinary double pole knife switch, the blades a a of which are pivoted to the
posts B B and adapted when the switch is closed, to engage with the contacts C C,
and thus connect the rheostat with the main or outside circuit; and D) is the
rheostat which consists of two rows of fixed contacts d d connected in series by
resistance coils as indicated by dotted lines in Fig. 2, and two brushes or spring
contacts attached to a cross-bar or head e on a longitudinally movable rod E.
The main switch A has a spring connection F with the movable part of the
rheostat. This connection preferably consists of a rod f pivoted at its lower end
to a depending arm or bracket e' attached to the rod E next to the cross-head or
arm e; two rods fi f¹ pivoted at their upper ends to a bracket on the cross-bar of
the switch A and passing loosely through a cross-bar f on the upper end of the
rod f, and attached at their lower ends to a cross-bar f³ loosely mounted and
adapted to slide freely upon said rod f, and a spiral spring f placed around said
rod between the cross-bars and f³. The cross-bar 2 is adjustably secured on
the rod by nuts threaded upon the upper end of said rod.
Between the upper end of the rod f and the bracket to which the rods f¹ are
pivoted at their upper ends, is interposed a plate f of rubber or other elastic
material which is perforated and loosely guided upon the rods f¹ and serves as a
cushion or buffer to prevent shock and jar to the apparatus when the main
switch is released and opened by the spring f. In place of this connection the
main switch may be connected directly with the movable part of the rheostat by
a simple spiral spring which is extended when the main switch is closed, or by
any other kind of yielding connection which will cause the movable part of the
rheostat to cut out the starting resistance when the switch is closed and to cut
in said resistance when the switch is opened, and which will open said switch
when it is released by its holding magnet.
The upward movement of the brushes or spring contacts d¹ of the rheostat is
retarded by a piston or plunger g attached to the lower end of the rod E and
working in a check cylinder or dash-pot G. The piston g is provided, as shown
in Fig. 1, with a cup-shaped leather or other suitable flexible packing g¹, which
tends to expand against the walls of the cylinder when the piston rises, but to
contract when the piston descends, thus permitting it to move quickly in that
direction. The upward movement of the piston is regulated by a valve or
screw which controls an air inlet opening in the lower head of the cylinder G.
The rod E passes through a stationary guide above the cylinder G.
The switch A and rheostat B are mounted upon a slate slab H or other suitable
insulating base.
I is a catch pivoted to the base plate and adapted to engage with and hold
the switch A closed. It has a depending arm i which is adapted to engage with
a notch in the back side and upper end of the rod E when said rod and the
brushes of the rheostat are in their lowest position and the resistance of the
rheostat is all included in the armature circuit. A spring pressing outwardly
against said arm i tends to throw the catch I out of engagement with the
switch A and its arm i into engagement with the rod E.
J is an electro-magnet which may be called the under-load or cut-out magnet.
It is mounted upon the upper part of the base plate H in position to act on a
rearward extension of the catch I, and when energized to hold said catch in
engagement with the main switch A, and its arm i out of engagement with the
rod E. is a dog or pawl pivoted to the catch I and pressed normally down-
ward by a spring into the path of the plate or projection a¹ with which said
catch engages on the cross-bar of switch A.
K is an electro-magnet which may be called the releasing or over-load magnet.
Its armature is provided with an adjustable weight and is pivotally con-
nected with one pole piece ³ which is insulated from the other pole piece 3 of the
magnet.
The circuit connections of the device, although susceptible of various modifi-
cations, may be made as indicated in Fig. 2 of the drawing.

page_text: 1 and 2 designate the main wires or conductors from the dynamo or generator.
They are attached to binding posts 3 and 4. These binding posts are connected
by fuses 5 5, with binding posts 6 and 7, which are in turn connected with the
contacts CC of the main switch. One of the pivot posts B of the main switch
is connected with one end of the coil of magnet K, while the other end of said
coil is connected with the upper of one row of the fixed rheostat contacts d, the
upper contact of the other row being connected with a binding post 8 to which
one of the armature conductors is attached. The other conductor of the armature
circuit is attached to the binding post 9, which is connected with the other pivot
post 1 of the main switch.
The circuit divides at the contact with which the coil of magnet K is con-
nected, this contact being connected with one terminal of the coil of magnet J.
The other terminal of this magnet is connected with the binding post 10 to
which one terminal of the field conductor of the motor is attached. The other
terminal of the field conductor joins that part of the armature circuit which is
attached to the binding post 9. One pole of the magnet K is connected with
the field circuit on one side of the magnet J, and the other pole ³ is connected
with the circuit on the opposite side of said magnet, thus forming a short circuit
which cuts out the magnet J when the armature k is brought into contact with
the pole k³.
The device operates as follows:
The circuit being open, the movable part of the rheostat in its lower position
with all the resistance in the armature circuit, and the arm i held by the spring
in the notch in the upper end of the bar E, the circuit is closed and the motor
started by turning the switch A upward into engagement with the contacts C.
This closes the circuit, current passing from the main line 1, binding post 3,
fuse 5, binding post ti to the contact C: thence through one blade a of the main
switch, pivot post B, the coil of magnet K, thence to the upper contact d on one
side of the rheostat. At this point the circuit divides and a part of the current
flows through the coil of magnet J to the binding post, thence through the field
of the motor, the other part of the current passing through the several resistance
coils and fixed contacts on one side of the rheostat, thence through the movable
contacts d to the other side of the rheostat, thence through the several, resistance
coils on that side to the binding post 8, thence through the armature of the motor
to the binding post 9, thence through the other side of the main switch A to the
main line 2. When this occurs the magnet J is energized and tends to move
the catch I into engagement with the plate a¹ on the cross-bar of the main
switch.
In closing the main switch its cross-bar is forced over the upper beveled end
of the rod E, thus forcing it slightly downward and releasing the arm, i, which
is thereupon drawn away from said rod against the opposing force of the spring i
hy the magnet J. At the same time the catch I is turned down into position to
engage with the plate a and hold the switch A closed. Said switch being now
released by the operator, is turned forward against the catch I by the spring f',
which has been compressed by closing the switch, and the brushes or movable
contacts d' are drawn upward by said spring over the fixed contacts d, thereby
gradually cutting out the resistance coils from the armature circuit until said
movable contacts rest upon the upper contacts d. All the resistance being
thus cut out of the armature circuit, current passes directly to the armature
unopposed except by the counter electro-motive force of the motor. As long as
normal current passes through magnet J it will retain the catch I in engagement
with the main switch, thus holding the latter closed; but if from any cause the
current through said magnet should cease or be reduced to a certain extent
according to the adjustment of said magnet, the catch I will be released and
forced by the spring out of engagement with the main switch A, which will
thereupon be instantly opened by the action of the compressed spring ft, thereby
breaking the circuit and allowing the motor to gradually come to rest.

page_text: As soon as the main switch is opened the rod E with the contacts d¹ of the
rheostat will descend and cut all the resistance into the armature circuit. When
the catch I is released by the magnet J the armi is turned and held against the
back of the rod E and will drop into the notch at its upper end as soon as it
reaches its lowest position, thus locking the movable part of the rheostat with
all the resistance in circuit until the main switch is again closed. If an attempt
should be made to close the main switch before all the resistance is in circuit,
the plate a¹ will strike against the end of the dog and prevent the blades a a
from engaging the contacts C, the outer end of the dog being held by the
engagement of the arm with the rod E in the path of the plate a¹ and thus
preventing the closing of the main switch until the notch in the upper end of
said rod is brought opposite the lower end of said arm and all the resistance is
in circuit.
If from any cause when the circuit is closed and the motor in operation an
abnormal increase of current should pass through the over-load magnet K, it
will draw its armature k up into contact with its pole ³, thus closing the short
circuit between the termini of the coils of magnet J and de-energizing said
magnet. Whenever this occurs the main switch A will be released and opened
and the resistance of the rheostat will be cut into circuit the same as when the
magnet J is de-energized by a cessation or abnormal reduction of current. In
neither case can the circuit be again closed until all the resistance has been cut
in by the descent of the movable contacts d¹.
If no current is passing through magnet J when the switch A is closed, the
arm i of catch I will not be disengaged from rod E and the resistance will not be
cut out, but as soon as the hand is removed from said switch it will fly open.
If from any cause current should be passing through magnet J before the
switch A was closed, then said switch could not be closed on account of the dog
being held by said magnet in position to prevent its closing.
The main switch A, under-load and over-load magnets J and K and catch I
may be employed together, substantially as shown and described, as an automatic
circuit breaker, without the rheostat.
A weighted connection may be substituted for the spring connection F between
the switch A. and movable contact of the rheostat D.
In place of the pivoted catch I the magnet J may be arranged to act directly
upon the switch A to hold it closed by attaching the armature to said switch;
and in place of a main switch like that shown, any other suitable kind for manu-
ally closing and automatically breaking the circuit may be used.
Various other modifications in the details of construction and arrangement of
parts may be made without materially affecting the operation of the device.
Having now particularly described and ascertained the nature of the said
invention as communcated to me by my foreign correspondent and in what
manner the same is to be performed, I declare that what I claim is:
1. In a starting box and automatic cut-out for electric motors, the combination
of a main switch for manually closing the main or outside circuit, a rheostat
comprising a series of fixed contacts connected by suitable resistance, and a
movable contact adapted to gradually cut out such resistance from the armature
circuit of the motor, a connection between the main switch and movable contact
of the rheostat which tends to automatically cut out said resistance from the
motor circuit when the main switch is closed, and to open said switch, and a
magnet adapted, while the normal current passes through it, to hold said switch
closed, substantially as and for the purposes set forth.
2. In a starting box and automatic cut-out for electric motors, the combination
of a switch for manually closing the main circuit; a rheostat comprising suitable
resistance, and a movable contact adapted to gradually and automatically cut
out such resistance from the armature circuit of the motor when said switch is

page_text: closed, a magnet arranged when the normal current passes through it to hold
said switch closed, and a magnet adapted, when subjected to an abnormal
increase of current, to de-energize the first mentioned magnet and release said
switch, substantially as and for the purposes set forth.
3. In a starting box and automatic cut-out for electric motors, the combination
of a switch for manually closing the circuit, a rheostat comprising suitable resist-
ance and a movable contact adapted to cut such resistance out of and into circuit
with the motor armature, a connection between the movable parts of said switch
and rheostat tending when said switch is closed to open it and to cut out said
resistance, a catch adapted to hold said switch closed and a magnet for holding
said catch in engagement with the switch while normal current passes through
the motor, substantially as and for the purposes set forth.
4. In a starting box and automatic cut-out for electric motors, 'the combination
of a switch for manually closing the circuit, a rheostat comprising suitable
resistance and a movable contact adapted to cut such resistance out of and into
circuit with the armature of the motor, a connection between the movable parts
of said switch and rheostat tending, when the switch is closed, to open it and to
cut out said resistance, a magnet adapted, while the normal current is passing
through it, to hold said switch closed and a detent adapted to hold the movable
contact of the rheostat at full resistance until the main switch is closed, and
then to release said contact, substantially as and for the purposes set forth.
5. In a starting box and automatic cut-out for electric motors, the combination
of a switch for manually closing the circuit, a rheostat comprising suitable
resistance and a movable contact adapted to cut said resistance into and to
gradually cut it out of circuit with the armature of the motor, a connection
between the movable parts of said switch and rheostat tending, when the switch
is closed, to open it and to cut the resistance out of circuit, a catch adapted in one
position to hold the movable contact of the rheostat at full resistance until the
switch is closed, and a magnet arranged to normally hold said catch in engage-
ment with said switch when it is closed, substantially as and for the purposes set
forth.
6. In a starting box and automatic cut-out for electric motors, the combination
of a switch for manually closing the main circuit, a rheostat comprising suitable
resistance, and a movable contact adapted to cut such resistance out of and into
the armature circuit of the motor, a spring connection between said switch and
movable contact tending, when said switch is closed, to open it and to cut out
said resistance, a catch adapted in one position to hold said switch closed, and
provided with an arm which is adapted to hold the movable contact of the rheostat
with all the resistance in circuit until said switch is closed, and a magnet arranged
to normally hold said catch in engagement with said switch, substantially as and
for the purposes set forth.
7. In a starting box and automatic cut-out for electric motors, the combination
of a switch for manually closing the circuit, a rheostat comprising suitable resist-
ance and a movable contact adapted to cut said resistance into and to gradually
cut it out of circuit with the armature of the motor, a connection between the
movable parts of said switch and rheostat tending, when the switch is closed, to
open it and to cut the resistance out of circuit, a magnet adapted to hold said
switch closed while the normal current passes through the motor, and a device
adapted to prevent the closing of the switch except when the movable contact of
the rheostat is at full resistance, substantially as and for the purposes set forth.
8. In a starting box and automatic cut-out the combination of a switch for
manually closing the circuit, a rheostat comprising suitable resistance and a
movable contact adapted to cut said resistance into and to gradually cut it out
of circuit with the armature of the motor, a connection between the movable
parts of said switch and rheostat tending, when the switch is closed, to open it
and to cut the resistance out of circuit, a pivoted catch for holding said switch
closed and provided with an arm which is adapted to bear against the movable

page_text: part of the rheostat and by engagement with a notch or offset therein to hold it
at full resistance until the switch is closed, a dog or pawl pivoted to said catch
and adapted to prevent the closing of the switch except when the arm of said
catch engages with the notch or offset in the movable part of the rheostat, and a
magnet for holding said catch in engagement with said switch while the normal
current is passing through the motor, substantially as and for the purposes
set forth.
9. In a starting box and automatic cut-out for electric motors, the combination
of a switch for manually closing the circuit, a rheostat comprising suitable resist-
ance and a movable contact adapted to cut said resistance into and out of circuit
with the armature of the motor, a connection between the movable parts of said
switch and rheostat tending, when the switch is closed to open it and to cut out
said resistance, a magnet adapted when traversed by the normal current to hold
said switch closed, and a cylinder and piston constructed and arranged to check
the movable part of the rheostat in cutting out resistance, substantially as and
for the purposes set forth.
10. In a starting box and automatic cut-out for electric motors, the combina-
tion with a suitable base, of a switch comprising an arm pivoted to said base for
manually closing the circuit, a rheostat comprising a number of fixed contacts
mounted upon said base and connected in series by suitable resistance, and a
longitudinally movable rod or bar having one or more contacts or brushes adapted
to be moved over said fixed contacts for cutting said resistance into and out of
circuit with the armature of the motor, a yielding connection between the switch
arm and movable part of the rheostat adapted to be strained by closing said
switch and tending to open said switch and to cut out said resistance, a pivoted
catch adapted to hold said switch closed and having an arm which is pressed by
a spring towards the movable rod or bar of the rheostat, and adapted by engage-
ment with a notch or offset therein to hold it at full resistance until the switch is
closed, a dog or pawl pivoted to said catch and adapted to prevent the closing of
the switch except when the arm of said catch is in engagement with said notch
or offset, a cut-out magnet adapted when energized by normal current to hold
said catch in engagement with said switch arm, and an over-load magnet adapted
when energized by abnormally strong current to short-circuit the cut-out magnet,
substantially as and for the purposes set forth.
11. In an automatic cut-out for electric motors, the combination of a switch
for manually closing the circuit, means tending to open said switch, a magnet
constructed and arranged, when energized by normal current, to hold said switch
closed, and to release the same when the current ceases or is abnormally reduced,
and a magnet constructed and arranged when subjected to abnormal increase of
current to de-energize the first mentioned magnet, substantially as and for the
purposes set forth.
12. In an automatic cut-out for electric motors, the combination of a switch
for manually closing the circuit, means tending to open said switch, a catch for
holding said switch closed, a magnet constructed and arranged, when energized
by normal current, to hold said catch in engagement with said switch, and to
release the same upon a cessation or abnormal reduction of current, and
magnet constructed and arranged when subjected to abnormal increase of current
to de-energize said first mentioned magnet and thus release the switch, substan-
tially as and for the purposes set forth."
a
13. In an automatic cut-out for electric motors the combination of a switch,
a magnet for holding the switch closed under normal conditions of current, and
a device constructed and arranged to prevent the closing of the switch while
said magnet is energized, substantially as and for the purposes set forth.
14. In an automatic cut-out for electric motors, the combination of a switch,
means tending to open said switch, a catch for holding said switch closed, and a
magnet constructed and arranged, when energized by normal current, to hold
said catch in engagement with said switch, but to release the same upon cessa-

page_text: tion or abnormal reduction of current, said catch being provided with means for
preventing the closing of said switch when said magnet is energized, substantially
as and for the purposes set forth.
Doted this 95th day of lanna 1900
BOULT & WADE,
Agents for the.Applicant.