Improvements in Electrically Controlled Elevators and Switch Mechanism for use therewith.
Year: 1892

page_text: Date of Application, 22nd Mar., 1892-Accepted, 11th June, 1892
COMPLETE SPECIFICATION.
Improvements in Electrically Controlled Elevators and Switch
Mechanism for use therewith.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of
Middlesex Gentleman do hereby declare the nature of this invention (which has
been communicated to me from abroad by Nelson Hiss of Baltimore Maryland
United States of America Manufacturer) 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 electrical apparatus or appliances for controlling the
movements of an elevator car from the several landings or floors of a building and
from within the car itself the object being to render unnecessary the services of an
attendant for the car.
The invention contemplates means whereby all the desired movements of the car
can be effected safely and with certainty, without the exercise of any more care and
intelligence than is required to touch a button corresponding to the number of the
floor to which the car is desired to move. To this end, the system comprises a
series of parallel or branch circuits, one for each floor, and electrically operated
devices so constructed that when one of the switches or push buttons is actuated
the car will move to and come to rest at that floor, no matter whether the car be
above or below the floor. This arrangement has obvious advantages over that
which requires one operation to cause the elevator car to ascend and another to
cause it to descend.
Electrical systems for controlling elevators have heretofore been devised by the
aid of which the car can be controlled either from the different floors or from within
the car itself; but in such systems interferences and confusion are likely to occur
in case some one at one of the landings attempts to control the car while it is in use.
According to the present invention means are provided whereby no one at any of
the floors can control the movement of the car so long as the same is occupied.
This is or may be practically accomplished by leading the outside or floor circuits
(as distinguished from the inside or car circuits) through a switch lever or circuit-
changer which is operated the moment a person enters the car (as by his weight on
the floor) so that outside control of the car is prevented until he leaves it.
The system is applicable to elevators employing notor mechanism of any sort,
and is constructed in such manner as to operate the stopping, starting and reversing
devices, which may be the valves of an ordinary hydraulic system, or a belt shipper,
or other well known mechanism. In carrying out my invention, I employ a main
circuit in two parallel branches, including a generator. When the current flows in
one branch the proper device is actuated to cause the car to ascend; when it flows
in the other branch the car descends; and when both branches are open the car is
at rest. I employ a secondary or auxiliary circuit which branches to each floor,
and also to a number of switches or push-buttons, in the car equal to the number of
floors. The function of these circuits is simply to operate the main circuit-closer.
There is one such main circuit-closer for each floor, and the main circuit includes
a movable portion (which may be a metallic ribbon or band) which moves with, or
in unison with, the elevator car, and this movable portion consists of two sections
insulated from each other, one section being permanently connected with that
branch of the main circuit which causes the ascent of the car, and the other section
It follows
being connected with that branch which causes the descent of the car.
that when the main circuit closer-of say one of the floors-is actuated and if the
car be above that floor the current will flow through one brach and cause the car to
descend to that floor but if the car be below that floor the current will flow through

page_text: the other branch and cause the car to ascend to that floor. The moving band
carries a mechanical circuit breaker, the position of which with reference to the
main-circuit closers is always the same as the position of the car with reference to
the several floors which these circuit-closers represent. This circuit-breaker acts
to open the main circuit and throw the circuit-closer back to its normal position at
the moment when the car reaches the floor at which it is desired to stop, and the car
accordingly comes to rest.
The main circuit closers could, be placed at the different floors, and the circuit-
breaker be carried by the car itself; but it is obviously advantageous to reduce
the length and complexity of the main circuit by employing a band or equivalent
device moving in unison with the car but over a inuch shorter path.
The invention is particularly applicable to elevator systems in which the power
is furnished by an electro-motor. In such case a switch is provided whereby the
current may be sent through the motor in one direction or the other to cause the
ascent or descent of the car, or the current may be cut off altogether to arrest
the car.
Such motor when in use is subjected to frequent and sudden reversals, and
is therefore liable to injury such as by the burning out of the coils, or the twisting
of the armature. To prevent such damage and to ensure the current being always
turned on gradually thereby giving the armature time to acquire momentum before
it receives the full strength of current an automatic switch is made a part of the
system, which switch introduces into the motor circuit a series of resistances cach
time the said circuit is broken, and removes these resistances one by one when the
said circuit is closed.
The invention in addition to the main features above indicated, includes certain
details of construction and combinations and arrangements of parts, as hereinafter
set forth.
In the accompanying drawings which form part of this Specification
Figure I is a diagrammatic view illustrating the electrical connections of the
system.
Figure I is a detail illustrating the position of the electric valves.
Figure II is a detail of one of the main circuit-closers,
Figures III and IV are details of the moving band or carrier and the circuit
breaker, and
Figures V and VI are details of the circuit changer for disconnecting the outside
circuits.
Figure VII is a front elevation of the automatic switch, .
Figure VIIY a vertical section thereof, and
Figure IX a top view, partly diagrammatic, illustrating the circuit connections
of the switch.
In Figures 1, V, and VI the circuits are shown as disconnected at the elevator
which is assumed to be loaded.
car,
In Figure I the system is shewn as applied to an ordinary hydraulic elevator of
which A represents the cylinder, B the piston, C the sheaves connected with the
piston, D the stationary sheaves, E the hoisting rope, and F the car. G represents
the inlet valve, by which water is admitted to the cylinder to force the piston down
(raising the car) and H the outlet valve.
Figure I shows the application of a well known forin of electric valve in which
the motions of a flexible diaphragm in chamber t are controlled by the electro-
maguets enclosed in a box u. The valve G in the pipe g follows the movements of
the diaphragm it being opened when the latter is raised and closed when depressed.
vis a pipe connecting the chamber with the pipe g. It is to be understood that
this valve forms no part of the invention, but being a device in common use is shown
merely as an example of one means which may be adapted to carry the invention
into effect when applied to hydraulic elevators.
The multiplying sheaves CD amplify the motion of the piston, which travels say
one-fourth the distance of the car. The endless band or carrier I is connected by
an arm k with the piston B, and therefore travels in unison with the car but over a

page_text: smaller path. This band, runs over small sheaves and carries portions o
branches of the main circuit which operates the valves G H. The band I may be
conveniently in the form of a metallic ribbon whose continuity is interrupted at the
two opposite points 1 and 2 (Figure 1). That portion of the band which is above
the break 1 is permanently included in branch 3 of the main circuit, while that part
which is below 1 is permanently connected with branch 4.
The switch boards a' a a³, one for each floor, are arranged at distances apart
corresponding to the distance between the floors, and each is provided with main
circuit closing mechanism such as shown in Figure II and hereafter described. The
main circuit proceeds from the generator X by wire 5 which connects by means of
branch wires 6 with the main-circuit closers at the several switch boards (sec
Figure 1) at each of which the circuit is normally open; thence it returns to the
generator by the band I and the branch 3 or 4 as the case may be.
The circuit closer M (Figure II) is a pivoted lever having a contact point m, and
provided with a spring N, which tends to force this contact point against the
travelling band I and thus electrically connect the wire 6 with the said band. The
latch Onormally holds the circuit closer out of contact with the band; but when
the circuit of the magnet P is closed, the circuit closer M is free to act to close the
main circuit.
Qis the mechanical circuit breaker attached to the band I at the point 1 where
the metallic strips are separated. It moves through the guide R as shown in
Figures III and IV, and throws back the circuit closer M until the latter is caught
by its latch O.
As the operation of working the valves, or operating other starting mechanism
requires considerable energy, the main circuit is made short and of as low resistance
as possible, using a separate circuit, supplied by the generator Y (or it may be by
the same generator X) for the contacts and switch mechanism in the car F and on
the several floors. Other advantages attend this arrangement as will be seen
hereafter.
Each
The secondary circuit requires very little energy, the only work it has to do
being to energize the magnet P which releases the main circuit-closer M.
floor has a switch or push button ¹³. Switch on the first or lowest floor is in
the circuit of the magnet P on switch board a¹ which corresponds with the first
floor, and so on. In the car are three similar switches or push buttons cc³ ³,
controlling the circuit closers at the switch boards a¹ a² a respectively.
The course of the auxiliary circuit and its several branches can be readily traced
on Figure 1. Beginning at one pole of the generator Y the wire 7 runs through
contacts controlled by the doors S on the several floors. This prevents the main
circuit from being closed, and consequently the car from moving so long as any
From the last door
door is open. This expedient, however, is not broadly new.
the circuit continues by wire 8 to the switch board a', where it is closed through
contacts op when the main circuit closer M is in its normal position (Figure II).
The secondary circuit is therefore broken as soon as the main circuit is closed,
which prevents more than one main circuit closer M from closing the main circuit
at the same time. It is not likely that two buttons would be pressed at exactly the
same instant; but to avoid confusion from such an event, it is proposed to make the
loops from the several floors of different resistance, so that one magnet will act
more promptly than the others. The circuit continues from switch-board a' by
wire 9 to switch board a² and by wire 10 to switch-board a³ each of which has a
similar provision for breaking it. It then proceeds by wire 11 to a rope or cable
which follows the elevator car, and in the latter it divides into three normally open
branches 12, 13 and 14 which include respectively the switches or push
buttons c¹ ce corresponding with the several floors of the building. Fellowing the
branch 12, we find it returns, through the rope or cable referred to, to the lower
switch-board a connecting by wire 15 with one end of the magnet coil P, and by
wire 16 with the main return wire 17, which leads to the opposite pole of the
generator Y. It will be seen by examination of the diagram that the branches 13

page_text: and 14 are similarly connected with the switch boards a² and a³ respectively, and
with the main return wire 17.
Returning now to wire 11 we find that before it reaches the push buttons in the
car, it connects with a branch wire 19 leading to a movable contact 21, which is
carried by a lever or scale-beam T, and normally pressed by a springt against a
fixed contact 22 on the floor of the car. The weight of a passenger standing on the
false bottom U which is pivoted at #, causes the beam T to tilt by pressing on the
short arm thereof, thereby separating contacts 21 and 22, and as these contacts are
in the circuit of the external push buttons 616 63 it follows that the elevator cannot
be controlled from the floors or landings so long as the car is occupied. This
circuit is completed as follows: From fixed contact 22 a wire 20 branches to each
push button 112 13. From button a wire 23 runs to wire 15, thence to the
magnet P of the first switch board a¹ and thence to the generator by wires 16
and 17. In like manner the push buttons are connected by wires 24 and 25
respectively with their corresponding, switch-boards.
The operation of the system will now be explained. The car being at the top
floor as shown in Figure I, the circuit-breaker Q will be between the circuit
closer M of the top switch board a3 and the travelling band 1. The door S of the
top floor must be closed before the car can move, and it is preferred to have means
for automatically closing the doors, as commonly employed. A person on the first
floor now desires to use the car and pushes the push-button . Here an advantage
of using a separate main circuit is seen; for it is not necessary for the person to
hold this button until the car arrives.
A momentary contact closes the auxiliary
circuit through the magnet P at switch board a', and the car at once starts and
continues to move until it reaches the first floor. Neither is it necessary to
ascertain whether the car be above or below the landing and to operate the proper
valve to make it descend or ascend as the case may be. We have seen that the
division 1 between the two metallic strips of band I is at the top floor; consequently
as soon as the button is pressed, magnet P at board a' is energized, the latch O is
lifted, the circuit-closer M released and the main circuit closed thereby, the current
flowing through the branch 4 which causes the descent of the car. Had the car
been below the first landing, the current would have flowed through the branch 3.
The car having started continues its descent and the circuit breaker Q travels down
in unison with it until it reaches the point of lever M. at board a' which it forces
back until engaged by latch O. At this moment the car reaches the first landing
and the main circuit being broken, comes to rest. During its descent, no one at an
intermediate station could control and arrest it, for as soon as the lever M was
released, it broke the auxiliary circuit between the wires 8 and 9 by separating the
contacts op (see Figure 1). The person who called the car can then open the
door which again breaks the secondary circuit, and as soon as he enters the car and
before the door can be closed behind him, his weight has separated the
contacts 21, 22 as already explained, thus breaking the outside branches of the
secondary circuit. When the door is closed, he touches the button in the car,
corresponding to the floor to which he desires to go, say button e². This closes the
circuit of the magnet P at the board a, the circuit being by the wire 15" to the
magnet P of the board a² and the wire 16 to the main return conductor 17.
the break in the travelling part of the main circuit is now beneath the second
floor switch-board a², the main circuit is closed by the circuit closing lever M
through the branch 3, causing the car to ascend until the circuit breaker Q again
opens it, by acting on the lever M at the board a² and this brings the car to rest at
the second floor.
As
For the sake of simplifying the description the connections for only three floors
are shewn but it will be obvious to persons skilled in the art that it may be applied
to any desired number of floors or landings.
The provision for preventing interference with the movements of the car while
in use by automatically breaking all the outside circuit connections, is considered
an important feature of the invention, and it may be carried out in different ways.

page_text: For example, as shown in Figure V the hoisting rope E is connected to an eye-
bolte which bears upon a spiral spring which is sufficiently strong to keep the
terminal 21, carried by the eye-bolt in contact with the fixed terminal 22, as long
as the car is empty. When the weight is increased by the entrance of a person
into the car, the contacts will be separated as shown.
The arrangement shown in Figure VI is similar in operation. The rope E is
attached to a lever T¹ beneath which is a strong spring which keeps the contact
plates 21, 22 together when the car is empty, and is compressed so as to
separate the contacts when the normal weight is increased by that of a passenger
or passengers.
In case the power for raising the car is supplied by an electro motor instead of
an hydraulic motor a switch actuating device is included in the branch 3 for
sending the current through the motor in one direction, and in the branch 4 n
similar device is included for sending the current in the opposite direction.
Suitable electric switch-mechanism for this purpose is illustrated in Figures VII
to IX in which GG" are the two switch controlling magnets, whose operation
will be presently described, these magnets being included in the two branches of
the ribbon circuit hereinbefore referred to.
A represents a tube of brass or other non-magnetic material. Around it are
five coils B B2 B3 B4 and B, the last being of fine wire, and the others of coarse
wire. Bx represents a soft iron core or plunger working within the tube A¹.
Core B is hollow and is closed at its lower end. C represents a rod running
down through the core B* and attached to the thimble or socket at the bottom
thereof, being however, electrically insulated by the bushing . The thimble />
encloses a small valve a covering the aperture a" in the end of the core B*. It
also has small lateral apertures at which establish a communication between the
aperture and the interior of the core. The cap a closing the brass tube A¹ has
a central perforation in which is a split regulating screw a°.
The object of this construction is to prevent the plunger or core B× from rising
abruptly when the current is turned on, the only entrance for air being through
the contracted passage containing the screw a
When the core 13× descends,
however, the valve a opens, permitting air in the tube to pass freely into the core,
so that air does not retard the descent of the plunger.
D represents a tube of hard rubber or other insulating material extending
partway down through tube A. To the outside of tube Dx are attached a series
of brass rings E', E, E and so on. The rod C has a metal loop C₁ carrying at
its upper end two semi-circular spring contacts or brushes C, adapted to slide
over and make electrical contact successively with the rings E' E2 and so on, the
object being to cut out one by one the resistances which are included in the
circuit when the current is turned on.
The resistance coils Y* are shewn as arranged in the case or box around the
solenoid, and each is connected by a wire y with one of the ring contacts E¹ E².
When there is no current through the apparatus, the motor-circuit beginning at
the post R¹ runs by flexible conductor 4 to the rod Cx, loop C¹, contacts C² and
lower ring E. This ring is connected by a wire y' with the binding screw/"
(see Fig. IX) each ring E' E³ and so on being connected in like manner with a
corresponding binding screw f3 and so on. Between the screws 1 and 2 is
connected one of the resistance coils indicated in Fig. IX by the dotted line Y*,
and between the screws f² and f³ a second resistance Y², but between the screws f³
and is connected the lowermost coil 13 of the solenoid. Thence the circuit
may be readily followed through the resistances Y3 and Y to the coil 12 of the
solenoid through the resistances Y Y and coil B³, to the resistances Y7, Y8,
through the coil B and resistance Y, to the binding post R² and thence to the
motor, as will be presently shewn.
As the core B rises, and the contacts C2 pass from ring E¹ to ring E2, the
resistance is cut out, and so on successively the several resistances as well as
the coils B B B³ B' are cut out until all are eliminated. This construction has

page_text: several important advantages. In the first place the coils of the solenoid are
utilized as resistances in the motor circuit, and by cutting out these coils
successively beginning at the bottom the stroke or path of movement of the
core B* may be greatly increased, the effect being practically to raise the active
part of the magnetic field as the core rises. The fine wire coil 13 is not in the
motor circuit, but is connected in a separate branch as will be hereinafter
explained. From what precedes, it will be understood that when the motor
circuit is broken, and the motor at rest, the plunger or core B* is in its lowest
position as shewn in Fig. VIII and that when the said circuit is closed the core B*
rises under the magnetic attraction of the solenoid, successively cutting out the
resistances and the solenoid coils B to B inclusive. The means for closing the
motor circuit so as to send the current through the motor in either direction will
now be explained.
We have already traced the motor circuit from post R¹ through the resistances
and coils B and so on to post R². From the post R2 a wire 9 leads to a binding
post H at the lowest part of the box (Fig. VII). There are three other
binding posts H2 H3 H₁ the post H serving for the return wire of the motor
circuit while to the posts H2 H3 the wires 14, 15 leading to the brushes of the
motor I are respectively connected.
From the post H', a wire 10 leads to the arm or bracket K and another wire 11
leads from the said post to an
arm or bracket K². To the arm K and an
intermediate arm or bracket K' are pivotted the switch levers L, L', these levers
being insulated from one another.
On the horizontal arms of these levers is carried the armature g of the switch
magnet G. The levers L L' carry at their lower ends caps L2 L³ containing cach
a carbon contact piece, and to the side of the box are attached complementary
carbon contacts L'. Normally the weight of the armature is such as to hold the
movable contacts away from the fixed contacts. When however, the magnet G¹
is excited, the circuit is closed through these contacts, as shewn in Fig. VIII.
The fixed carbon L' is connected by a wire 12 with the post H³, and a wire 13
connects the adjacent contact (corresponding to the movable contact L³) with the
post H³. The magnet G is provided with arrangements similar to those of
magnet G¹, the switch arms being represented by the letters M* M', and the caps
by the letters M2 M3. The connection of the motor circuit can now be traced
through the switch mechanism. From the post Hit proceeds by the wire 10 to
the arm K, lever L, cap and carbon L2, fixed carbon L, wire 12 post H2 to the
motor by wire 14. Returning by wire 15, it proceeds by the post H³, wire 13,
cap L³, lever L, arm K', wire 16, post H', and wire 17 to post R³, to which the
return wire of the motor circuit is connected.
When the circuit of the magnet G¹ is open and that of G" closed, the motor
circuit is completed from the post H' through the motor by the wire 11, arm K,
switch lever M cap M³ and wire 18 to the binding post H³. The direction of
the current is now reversed, flowing through the motor by the wire 15, and
returning by the wire 14 to the post H2 thence by the wire 19 and cap M² to
the switch lever M*, arm K', and wire 16 to the return binding post H.
The circuits of the magnets G¹ G" (which are adapted to be closed by the
main circuit closer M through the ribbon I, as already explained) will now be
traced. On the top of the case are two posts ar z; one terminal of the controlling
circuit is connected to post a from whence a wire 23 (Fig. VIII) runs to the fine
wire coil B³ of the solenoid, from which the return wire 22 leads to the post.
The latter is connected by wire 24 with post P' (Fig. VII) whence a wire 25
leads to the coils of the magnet G', from which a wire 26 connects with a
spring p³, a companion spring being connected by a wire 27 with post P³.
When the circuit of the magnet G" is open its armature g¹ rests upon and connects
the springs p, p, (as shewn in Fig. VII). But when the coils of the magnet G
are excited, the circuit of the companion magnet G¹ is broken between the
springs p p. The circuit of the magnet G" proceeds from the post P2 (where

page_text: UT the two magnets branch or divide) by wire 20 to the cons of the
magnet G, thence by the wire 29 to spring p, armature g of magnet G', spring p'
and wire 30 to post P¹.
Inasmuch as the fine wire coil 13 of the solenoid is in that part of the controlling
circuit which is common to both magnets GG", the core or plunger B* will
always be sustained in its highest position so long as the controlling circuit is
closed through either of the switch magnets.
The operation of the apparatus as a whole will be readily understood. To start
the motor the user closes the controlling circuit through the magnet Gor G
according to the direction in which it is desired to rotate the armature shaft. The
current Hows through the fine wire coil B and through the coils say of the
magnet G, which thereupon attracts its armature, breaking the circuit of the
magnet at the springs p' p, and closing the main circuit through the switch
arms L L. At this moment all the resistances and the short coils B'-B' of the.
solenoid are in circuit, but as the core B* ascends, it cuts these out successively, so
that the full strength of the current is turned into the motor by degrees. To
reverse the motor, the circuit of magnet G" must be closed, but this cannot be
done abruptly and while the resistances are cut out, for the reason that, it is
necessary first to open the circuit of the magnet G¹. Until that is done the circuit
of magnet G remains open at the springs p³ p^.. When the circuit of the
magnei is broken, the coil 13 of the solenoid is thrown out of circuit and the
core B* descends by gravity, the valve a opening, so that the air in tube A'
passes freely through the socket without offering resistance to the descent of
the plunger.
It will be obvious to skilled electricians that parts of the invention may be used
separately and that details of construction and arrangements of parts may be varied
without departing from the nature of the invention.
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
1. In systems for controlling elevators electrically, the arrangement of an
electric circuit controlling the starting and stopping mechanism, the said circuit
including main circuit-closers for the several floors or landings, and an auxiliary
circuit including magnets for operating the said circuit-closers, and provided at
convenient points with push buttons or equivalent devices, substantially as and for
the purpose hereinbefore described.
2. In systems for controlling elevators electrically, the combination of the
conducting strips or ribbons travelling with the car and connected with the two
branches respectively of the controlling circuit, main circuit-closers, one for each
floor, and devices as specified for operating each circuit closer from its corre-
sponding floor, so as to close the controlling circuit through one branch or the
other according as the car is above or below such floor, substantially as hercin-
before described.
3. The combination of the controlling circuit having two branches, one to cause
the ascent of the car and the other to cause its descent, two conducting strips
having their ends in close proximity and connected with the said two branches
respectively, circuit-closers, one for each floor adapted to make contact with one
strip when the car is above the floor corresponding therewith, and vice versa, and a
circuit breaker also travelling with the car so as to disengage each main circuit-
closer as the car reaches the floor to which it corresponds, substantially as herein-
before described.
4. The combination of the main circuit having a movable portion, main circuit
closers for the several landings and an auxiliary circuit having branches with
switches or push buttons at each landing and including magnets in each branch for
controlling the corresponding circuit closer, the said auxiliary circuit including

page_text: also a series of contacts one of which is broken whenever one of the circuit closers
is actuated to close the main-circuit, substantially as herein before described.
5. The combination with the main circuit-closers operating as described, of the
circuit-breaker carried by the travelling band or ribbon to open the circuit and
arrest the car when the latter reaches the landing at which the circuit-closer has
been actuated, substantially as herein before described.
6. The combination with electric circuits and appliances for controlling the
movements of an elevator car from the several floors or landings of a building, of
means for disconnecting the exterior circuits when a person enters the car,
substantially as hereinbefore described.
7. Switch or circuit-changing appliances operated by the weight of an occupant
of the car for breaking the exterior circuits while the car is occupied substantially
as hereinbefore described.
8. The combination of the electric controlling circuit and appliances, and a
movable platform in the car, operating contacts whereby the weight of the
occupant disconnects or opens the exterior controlling circuits, substantially as
hereinbefore described.
9. The construction and arrangement of devices constituting an automatic
electric switch, whereby the flow of current is reduced by including a series of
resistances in the circuit when the latter is first closed, and the flow gradually
increased by eliminating the resistances one by one, substantially as shewn and
described with reference to Figs. VII, VIII and IX of the accompanying
drawings.
10. The combination of an electric circuit, a series of resistances having their
terminals connected to fixed contact plates, a solenoid, its core carrying a spring
or brush permanently connected in said circuit and adapted, when the core is
attracted, to make contact with said contact plates successively, thereby cutting
out said resistances seriatim, substantially as hereinbefore described.
11. The combination of an electric circuit, a solenoid having several independent
coils, a spring or brush carried by the core of the said solenoid and closing a
circuit through the end coil thereof when said core is in its normal position, but
adapted to cut out the said coil when the core is attracted, substantially as herein-
before described.
:
12. The combination of an electric circuit, a series of resistances having their
terminals connected with fixed contact plates, a solenoid having several independent
coils connected in series with said resistances, and having also a coil connected in a
separate circuit, and a contact spring or brush carried by the core of the said
solenoid, and adapted when the core is attracted to make contact successively with
the said contact plates thereby cutting out the said resistances and also the coils
of the solenoid connected therewith, substantially as hereinbefore described.
13. The combination with an electric circuit and with switch mechanism for
opening and closing the same, of a solenoid having several independent coils, a
core carrying a spring contact or brush connected in the said circuit, a series of
resistance coils including one or more of the solenoid coils, and terminal plates
with which the said resistances are connected, the said plates being arranged in the
path of the spring contact or brush carried by the core, whereby the resistances
are switched in and out of circuit, substantially as hereinbefore described.
Dated this 22nd day of March 1892.
J. H. JOHNSON & Co.,
Agents.