Improvements in Systems of Electrical Control for Elevators.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
[Communicated from abroad by FRANK JULIAN SPRAGUE, a citizen of the United
States of America, of No. 20, Broad Street, in the Borough of Manhattan,
in the City, County and State of New York, United States of America, Manu-
facturer.]
Improvements in Systems of Electrical Control for Elevators.
I, HENRY HARINGTON LEIGH, Assoc.M.Inst.C.E., Fel.Ch.Inst.P.A., F.I.Inst.,
practising as Phillips and Leigh, of No. 22, Southampton Buildings, Chancery
Lane, in the Administrative County of London, Engineer and Patent Agent, do
hereby declare the nature of this invention to be as follows:-
1
These improvements relate especially to a system of electrical control for
elevators, and the drawings illustrate an elevator which is designed not to require
a skilled attendant, so that it can be used in private houses. With this end in
view, the control system is arranged so that the closure at a button at any landing
will cause the elevator car to travel and stop automatically at that landing.
Buttons which correspond to the several landings are located within the car, an
these are so connected that the closure of the button corresponding to a given
landing will cause the car to travel toward that landing and automatically stop
at the landing.
The improvements relate also to various safety devices by which conflicting or
inoperative combinations of circuits are prevented, and to various other features
of construction which will appear in the drawings and specification.
In the accompanying drawings, which form a part of this specification,
Figure 1 is a diagram showing the wire connection between the various parts
of the elevator system.
Fig. 2 is a plan view of the hoisting mechanism, together with the main and
floor-lim't switches and the control apparatus which are mounted on the same
base.
Fig. 3 is a view of the same from one side.
Fig. 4 is a view of the same from another side, together with the car, overhead
sheaves and counter-weight.
Fig. 5 is a vertical section through a portion of the hoistway showing a landing
entrance-way and car broken away.
Fig. 6 is an elevation of an entrance-way,
Fig. 7 is a horizontal section through an automatic entrance lock on the line r
of Fig. 6.
Fig. 8 is a horizontal section through the door switch on the line of Fig. 6.
Figs. 9 and 10 are vertical transverse sectional views through a landing push-
button.
Fig. 1 is a vertical transverse section through the apparatus carrying the
floor and main-limit switches.

page_text: HOISTING MECHANISM..
The hoisting mechanism consists of a winding drum 1 suitably mounted and
connected to a dynamo-electric machine 2 through worm-gearing. The armature
of the machine is directly coupled to the worm-shaft 3. On the worm-shaft is
a worm 4 which engages with a worm-wheel 5. The threads of the worm are of
such pitch that the worm-wheel may drive the worm and the machine be run ag
a generator and pay energy to the line. The worm and worm-wheel are covered
by a casing 6 so that they may be run in oil. At the end of the worm-shaft is a
thrust-bearing 7 which consists of a thrust-plate carried by the shaft, and stationary
thrust-plates on either side, and balls or rollers interposed to reduce the friction.
Also on the shaft is a brake-wheel 8, against which brakes are applied by a spring 9.
The brakes are held off by a magnet which will be described later. Car-cables 10
and counterweight-cables 11, cach consisting of two ropes, are shown on the hoist-
ing drum. The car-cables are led from the drum directly up the hoistway and
over a sheave 12 to the car 13. The counterweight-cables lead from the other
side of the drum, under an idler 14, up the hoistway, and over two sheaves 15,
one of which is behind the sheave 12, to the counter-weight 16. The car is pre-
ferably overcounterweighted to the extent of a part of the load which the elevator
is designed to carry. The dynamo-electric machine will consequently act some-
times as a motor and sometimes as a generator.
ELECTRICAL SYSTEM.
The current for all the electrical circuits is led to two. leads A B through a main
switch 17. These circuits may, in a general way, be grouped into three classes;
but in each of the circuits are various branches. These three classes of circuits
are the controlling circuits, the field and brake circuits, and the armature circuit.
All the circuits lead through contacts which are controlled by two relays, an up-
relay U which is operated when the car is ascending, and a down-relay D which
is operated when the car is descending.
THE ARMATURE, CIRCUITS.
The armature of the dynamo-electric machines is connected to the line in one
direction or the other, according to the direction in which the car is to travel.
There are branches from both the leads A and B to each relav. A branch from
one brush of the machine is connected to a contact 18 through which it will be
closed to lead A when the up-relay is energized. Another branch from the same
brush is connected with a contact 19 through which it will be closed to lead B
when the down-relay is energized. From the other brush of the machine the
circuit is through a starting resistance 20 from which it branches to two contacts
one of which 21 is closed to lead B when the up-relay is, energized, and the other
of which 22 is closed to lead A when the down-relay is energized. It will therefore
be seen that the energizing of either relay will connect the armature of the machine
through the starting resistance to the two leads A and B, one relay connecting
the armature to the leads in the opposite direction from the other. There is a third
circuit through the armature which is closed through the contacts 23 23 and
stopping resistance 24 when neither relay is energized. It will be seen that the
field circuit is broken before the armature is short-circuited through the stopping
resistance 24, but there is usually enough residual magnetism in the field to cause
the armature to generate current and act as a dynamic brake on the machinery.
If desired, the relays may merely cut resistance into the field without completely
breaking the circuit, and rheostat 20 may be utilized for this purpose, the con-
nections being modified so that this can be done.
FIELD AND BRAKE CIRCUITS.
When either relay is energized. a contact 25 is closed to lead A and a con-
tact 26 is closed, to lead B. The wire which leads from contact 25 divides into
two branches. In one branch is the field coil 27 of the dunema-electric machine

page_text: In the other branch is the coil of the brake-magnet 28, and the solenoid 29 of the
rheostat. The two branches then unite and pass through a shunted switch 30
and thence to contact 26. The shunted switch is opened by the rheostat when it
is fully operated, thus throwing resistance 31 into the circuit. This weakens the
field, which increases the speed of the machine, and it saves current in the brake-
magnet coil and solenoid.
CONTROLLING CIRCUITS.
The car, can be controlled from within, or from where the hoisting apparatus
is located, and it can be brought by the several landing buttons to any landing
and automatically stopped. The elevator cannot be operated from the car itself,
or any landing, if the door at any landing is open or the cable is slack, and can-
not be operated from any landing if the car is occupied. Nor can it, while a land-
ing-button is closed, be operated from any other landing. The controlling circuits
are provided with car-buttons and landing-buttons, floor-limit switches, and
various safety switches, and with two relays, one the up-relay and the other the
down-relay, which control the field and brake circuits and the armature circuits.
The controlling circuits are all branched from a wire which is connected to
line A through a throwover switch 32, by means of which the line can be connected
at will to the landing system and the car-controlling system, or to the push-
buttons 33 34 of the control-board, which is intended to be placed near and may
be mounted on the base of the hoisting apparatus as shown. The push-buttons of
the control-board are connected directly to the floor-limit switches. The wire
from the lead A, which passes through the car-side of the throwover switch, passes
through a locking magnet 35 at each landing. These magnets lock the push-
buttons at the landings. There is also a door-switch 36 for each landing in
series in the controlling circuit. After passing through these magnets and door
switches, the wire is led to the car. First it traverses a slack-cable switch,37,
and then it branches. One set of branches goes to the car-buttons and through
them to the landing-wires a₁ α, az and a, and a separate branch, goes through
a switch 39 of the car-gate 40 and the car-cable,, whence it branches to the several
landing-buttons through which it may be closed to the several landing wires. It
is essential to operation by a landing push-button or a car push-button that all
of the landing-doors and the slack-cable switch be closed; and it is essential to
operation from any landing push-button that the car-gate be closed. The car-
gate is hinged to one corner of the car, and is in front of the entrance when the
car is not occupied. Its switch is closed only when it is in this position. It
reaches entirely across the car, so that a person cannot pass around its end, and
it must consequently be folded back into the car when the car is occupied, and can
be closed only when the car is not occupied. The landing-buttons 41 comprise
a switch-arm 42, which, when pushed in, will close the circuit at the landing,
unless the circuit is open at the throwover switch, or at some other point, as, for
example, the slack-cable switch, a landing-door switch, the car-gate switch, or
another push-button has been closed. When a button is pushed in and the circuit
is closed, the armatures 43 of the locking-magnets are all lifted, and the switch-
arm of the operated push-button is locked in, and the switch-arms of the other
buttons are locked out by the engagement of hooks on the ends of the armatures
with the switch-arms. This condition continues until the control-circuit is opened
at some point. The landing-wires of the intermediate and the top landings pass
through floor-limit switches 44 and thence to the coil of the up-relay; and the
landing wires from the lowest landing and the intermediate landings pass through
floor-limit switches 45 and thence to the coil of the down-relay. These switches
are mounted together on a slate, and are opened and closed by arms 46 which are
clamped to a shaft 47 connected to the drum-shaft through the gears 48 and
chain,49. The arms 46 move synchronously with the drum, and hence with the
elevator. These arms can be independently adjusted on the shaft, and when the
elevator is set up, they are so adjusted that when the car is ascending or descend-
1

page_text: ing, each landing wire will be open at a floor-limit switch as the corresponding
landing is approached, and sufficiently in advance to give the car time to lose its
momentum and stop at the landing. In the same mechanism with the floor-limit
switches is an upper main-limit switch 50 and a lower main-limit switch 51. The
former is in circuit with the armature of the dynamo-electric machine, the field, the
brake-magnet and the solenoid of the rheostat, when the car is ascending, and the
latter is similarly in circuit when the car is descending. The effect of opening
either main-limit switch is the same as opening the corresponding relay-contacts,
and they are to insure the cutting off of current and the stopping of the car at the
limit of travel in the event of failure of the relays to operate properly. After
passing a relay, the circuit is through one of two contacts 52, 53, contact 52 being
in the circuit with the up-relay coil, and controlled by the down-relay, and con-
tact 53 being in circuit with the down-relay coil, and controlled by the up-relay,
each being opened when its controlling relay is energized. This arrangement
prevents one relay from being energized if the other is energized, or the simul-
taneous operation of both relays. From contacts 52 53 connection is made to
lead B through a contact 54 which is opened as soon as the solenoid is energized
and commences to cut out resistance at the rheostat. This solenoid, as already
explained, cannot be energized until one of the relays has operated its armature,
and when this is done, the controlling circuit is closed to line at contact 20, which
is independent of contact 54. This arrangement prevents the re-energizing of a
relay after the circuit has been broken, until the rheostat has cut in all the
resistance.
It will be seen that in the system herein illustrated, there is a circuit-closer for
each direction of motion, upon the closure of which the machine is at once con-
nected to the line, and upon opening which the machine is at once disconnected
from the line. After either circuit-closer has been opened, neither can affect the
connections of the machine until all of the controlling mechanism has returned to
position of rest.
The landing doors are provided with springs by which they are automatically
closed, and with latches 55 of ordinary character, which can be retracted from
either side of the door. There is an additional latch 56 in the door-jamb at each
landing, which locks the door. This latch is retracted automatically when the
car is opposite the landing by the engagement of a cam 57 on the car with the
cam-roller 58 which is mechanically connected with the latch.
Doted this 20th
1000
I, HENRY HARINGTON LEIGH, Assoc.M.Inst.C.E., Fel.Ch.Inst.P.A., F.I.Inst.,
practising as Phillips and Leigh, of No. 22, Southampton Buildings, Chancery
Lane, in the Administrative County of London, do hereby declare the nature of
this invention (which has been communicated to me from abroad by Frank Julian
Sprague, of No. 20, Broad Street, in the Borough of Manhattan, in the City, County
and State of New York) and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
These improvements relate especially to a system of electrical control for
elevators. The drawings illustrate an elevator which is operated by an electric
motor, the circuits of which are electrically controlled. Two sets of contacts are
provided, one of which connects the motor-armature to the source of current supply

page_text: in one direction, and the other of which, connects the motor in the opposite
direction. A rheostat is also provided for varying the resistance in the armature
circuit. Its mechanism is separate from the sets of contacts for connecting the
motor to the source of supply since its action needs to be gradual, while it is
desirable that the contacts connecting to the source of supply should open and
close instantaneously. Between the rheostat and the means for operating the
sets of contacts are devices for preventing the operation of the rheostat to cut 'out
resistance until one of the sets of contacts has been closed, and for preventing the
closure of either set of contacts if the other set is closed, or resistance is cut out
at the rheostat.
This system of control is applicable to an elevator mechanism in which the
counter-weight exceeds the weight of the car. This excess is usually made equal
to the average load that the car is expected to carry. Consequently, when the
elevator is going up, if the load is less than the excess counter-weight, the hoisting
mechanism will drive the dynamo-electric machine, and it will run as a generator
and pay energy to the line; but, if the load is greater than the excess counter-
weight, the machine will run as a motor. When the elevator is going down, both
of the above conditions will be reversed. A shunt machine, when connected to
leads on which a constant potential is maintained, tends to run at a certain speed,
regardless of whether it is called upon to act as a generator or as a motor. The
motor, as the machine will be called for simplicity, will, therefore, hold the
elevator at a constant speed regardless of whether it is running with or against
the load. But, under the usual conditions of elevator service, such a motor would
start too rapidly, if the load in the car is such that the hoisting mechanism will
run of its own accord in the same direction. This difficulty is avoided by pro-
viding the motor with a strong field while the armature is being connected to the
leads and the resistance is being cut out, and having the motor so wound and
geared that it will drive the elevator at a slower speed than is required for service.
After the connections have been made and the resistance in the armature-circuit
has been cut out, the desired service speed is obtained by weakening the field.
The elevator, as shown in the drawings, is intended for light service in houses
where it is not desirable to employ a skilled attendant. With this end in view,
the control system is arranged so that the closure at a button at any landing will
cause the elevator car to travel toward and stop automatically at that landing.
Buttons which correspond to the several landings are located within the car,
and these are so connected that the closure of the button corresponding to a given
landing will cause the car to travel toward that landing, and automatically stop
at the landing.
In working out these features, various novel features have been introduced.
Upon the closure of the controlling circuit at a car push-button or any landing
push-button, the unoperated push-buttons at the several landings are simul-
taneously locked open so that no conflicting circuit can be established at another
point. The wire from each landing push-button is connected to the up or down
controlling-c reuit accordingly as the car requires to be brought up or down to the
landing at which the button is located.
In the drawings left with the Provisional Specification, which are hereby made
a part of this specification:
Figure 1 is a diagram showing the wire connections between the various parts
of the elevator system.
Fig. 2 is a plan view of the hoisting mechanism, together with the main and
floor-limit switches and the control apparatus which are mounted on the same
base.
Fig. 3 is a view of the same from one side.
Fig. 4 is a view of the same from another side, together with the car, overhead
sheaves and counter-weight.
Fig. 5 is a vertical section through a portion of the hoistway showing a landing
entrance-way and car broken away.

page_text: ace-way.
Fig. 7 is a horizontal section through an automatic entrance lock on the line.
of Fig. 6.
Fig. 8 is a horizontal section through the door switch on the line of Fig. 6.
Figs. 9 and 10 are vertical transverse sectional views through a landing push-
button.
Fig. 11 is a vertical transverse section through the apparatus carrying the
floor and main-limit switches.
HOISTING MECHANISM.
The hoisting mechanism consists of a winding drum 1 suitably mounted and con-
nected to a dynamo-electric machine or motor 2 through worm-gearing. The
armature of the motor is directly coupled to the worm-shaft 3. On the worm-
shaft is a worm 4 which engages with a worm-wheel 5. The threads of the worm
are of such pitch that the worm-wheel may drive the worm and the machine be run
as a generator instead of a motor and convert mechanical into electrical energy and
Fay it to the line. In designating the machine as a motor it is not intended there-
fore to indicate that its function is limited to the conversion of electrical into
mechanical energy. The worm and worm-wheel are covered by a casing 6 so that
they may be run in oil. At the end of the worm-shaft is a thrust-bearing 7 which
consists of a thrust-plate carried by a shaft, and stationary thrust-plates on either
side, and balls or rollers interposed to reduce the friction. Also on the shaft is
a brake-wheel 8, against which brakes are applied by a spring 9. The brakes are
held off by a magnet which will be described later. Car-cables 10 and counter-
weight cables 11, each consisting of two ropes, are shown on the hoisting drum.
The car-cables are lead from the drum directly up the hoistway and over a sheave 12
to the car 13. The counter-weight cables lead from the other side of the drum,
under an idler 14, up the hoistway, and over two sheaves 15, one of which is behind
the sheaves 12, to the counter-weight 16. The car is preferably over-counter-
weighted to the extent of a part of the load which the elevator is designed to carry.
The dynamo-electric machine will consequently act sometimes as a motor and
sometimes as a generator.
ELECTRICAL SYSTEM.
The current for all the electrical circuits is lead from two leads A, B which
constitute a source of current supply through a main switch 17. These circuits
may, in a general way, be grouped into three classes; but in each of the circuits
are various branches. These three classes of circuits are the controlling circuits,
the resistance controlling, field and brake circuits, and the armature circuits. All
the circuits lead through contacts which are controlled by two relays, an up-relay U
which is operated when the car is ascending, and a down-relay D, which is operated
when the car is descending.
THE ARMATURE CIRCUITS.
The armature of the motor is connected to the source of current supply in one
direction or the other, according to the direction in which the car is to travel.
There are branches from both the leads A and B to each relay. A branch from
one brush to the motor is connected to a contact 18 through which it will be closed
to lead A when the up-relay is energized. Another branch from the same brush
is connected with a contact 19 through which it will be closed to lead B when
the down-relay is energized. From the other brush of the machine, the circuit
is through a starting resistance 20 from which it branches to two contacts, one
of which 21 is closed to lead B when the up-relay is energized, and the other of
which 22 is closed to lead A when the down-relay is energized. These two branches
constitute respectively the up-circuits and the down-circuits of the motor armature.
It will therefore be seen that the energizing of either relay will connect the
armature of the motor through the starting resistance to the source of supply,

page_text: one realy connecting the armature to the source of supply in the opposite direction
from the other. There is also a close-circuit through the armature which is
closed through the contacts 23 and stopping resistance 24 when neither relay is
energized. It will be seen that the field circuit is broken before the armature is
close-circuited through the stopping resistance 24, but there is usually enough
residual magnetism in the field to cause the armature to generate current and act
as a dynamic brake on the machinery. If desired, the relays may merely cut
resistance into the field without completely breaking the circuit, the connections
being modified so that this may be done.
RESISTANCE-CONTROLLING, BRAKE AND FIELD CIRCUITS.
0
When either relay is energized, a contact 25 is closed to lead A and a contact 26
is closed to lead B. The wire which leads from contact 25 divides into two
branches. In one branch is the field coil 27 of the dynamo-electric machine.
In the other branch is the coil of the brake-magnet 26, and the solenoid 29 of the
rheostat, which actuates a traveling contact block to vary the resistance in the
armature circuit. As shown, the rheostat varies the resistance without breaking
the circuit, and when in the normal position to which it returns by gravity, all
the resistance is cut in. But for some purposes this normal position might be
one in which the circuit is broken after cutting in all the resistance. The two
branches then unite and pass through a shunted switch 30 and thence to contact 26.
The shunted switch is opened by the rheostat when it is fully operated, thus
throwing resistance 31 into the circuit. This weakens the field, which increases
the speed of the machine, and it saves current in the brake-magnet coil and rheostat
solenoid. The rheostat, brake, and motor field are shown partly in series and
partly in parallel, but their precise arrangement in the various branches is
immaterial, provided that the resistance in each branch is adjusted so that the
required current will pass. The circuit through the rheostat-solenoid will be
termed the resistance-controlling circuit.
CONTROLLING CIRCUITS.
The car can be controlled from within, or from where the hoisting apparatus is
located, and it can be brought by the several landing buttons to any landing and
automatically stopped. The elevator cannot be operated from the car itself, or
any landing, if the door at any landing is open or the cable is slack, and cannot
be operated from any landing if the car is occupied. Nor can it, while a landing
button is closed, be operated from any other landing. The controlling circuits
are provided with car-buttons and landing-buttons, which are the circuit-closing
devices of the controlling-circuits, floor-limit switches, and various safety switches,
and with two relays, one the up-relay and the other the down-relay, which control
the field and brake circuits and the armature circuits.
The controlling-circuits are all branched from a wire which is connected to line A
through a throwover switch 32, by means of which the line can be connected at
will to the landing system and the car-controlling system, or to push buttons 33 34
of the control-board, which is intended to be placed near and may be mounted
on the base of the hoisting apparatus as shown. The push-buttons of the control-
board are conected directly to the floor-limit switches. The wires from the lead A,
which passes through the car-side of the throw over switch, passes through a locking
magnet 35 at each landing. These magnets lock the push-buttons at the landings.
There is also a door-switch 36 for each landing in series in the controlling-circuits.
After passing through these magnets and door-switches, the wire is lead to the car.
First it traverses a slack-cable switch 37, and then it branches. One set of
branches goes to the car-buttons and through them to the landing-wires a, a, az
and a., and a separate branch goes through a switch 39 of the car-gate 40 and the
car-cable, whence it branches to the several landing-button through which it may
he closed to the several landing-wires. It is essential to operation by a landing
push-button cz a car-push-button that all of the landing doors and the slack-cable

page_text: switch be closed; and it is essential to operation from any landing-button that the
car-gate be closed. The car-gate is hinged to one corner of the car, and is in front
of the entrance when the car is not occupied. Its switch is closed only when in
this position. It reaches entirely across the car, so that a person cannot pass around
its end, and it must consequently be folded back into the car when the car is
occupied, and can be closed only when the car is not occupied. The landing-
buttons 41 comprise a switch-arm 42, which, when pushed in, will close the circuit
at the landing, unless the circuit is open at the throwover switch, or at some other
point, as, for example, the slack-cable switch, a landing-door switch, the car-
grate switch, or another push-button has been closed. When a button is pushed
in and the circuit is closed, the armatures 43 of the locking-magnets are all lifted
and the switch-arm of the operated push button is locked in, and the switch-
arm of the other buttons are locked out by the engagement of hooks
on the ends of the armature with the switch-arms. This condition continues until
the control-circuit is opened at some point. The landing-wires of the inter-
mediate and the top landings pass through the floor-limit switches 44 and thence
through the up-controlling circuit to the coil of the up-relay; and the landing
wires from the lowest landing and the intermediate landings pass through the
floor-limit switches 45 and thence through the down-controlling circuit in which
the down-relay coil is located. The floor-limit switches are mounted together
on a slate, and are opened and closed by arms 46 which are clamped to a shaft 47
connected to the drum-shaft through the gears 48 and chain 49. The arms 46
move synchronously with the drum. and hence with the elevator. These arms can
be independently adjusted on the shaft, and when the elevator is set up, they are
Fo adjusted that when the car is ascending or descending, each landing-wire will
be opened at a floor-limit switch as the corresponding landing is approached, and
rufficiently in advance to give the car time to lose its momentum and stop at the
landing. In the same mechanism with the floor-limit switches is an upper main-
limit switch 50 and a lower main-limit switch 51. The former is in circuit with
the armature of the dynamo-electric machine, the field, the brake-magnet and the
solenoid of the rheostat, when the car is ascending, and the latter is similarly in
circuit when the car is descending. The effect of opening either ma'n-limit switch
is the same as opening the corresponding relay-contacts, and they are to insure
the cutting off of current and the stopping of the ear at the limit of travel in the
event of failure of the relays to operate properly. Each of the controlling-circuits
is through one of two contacts 52, 53. the up-controlling circuit being through
contact 52 which is controlled by the down-relay, and the down-controlling circuit
being through the contact 53, which is controlled by the up-relay, each being
opened when its controlling relay is energized. This arrangement prevents one
relay from being energized if the other is energized, or the simultaneous operation
of both relays. From contacts 52 53 connection is made to lead B through con-
fact 54 which is opened as soon as the rheostat solenoid is energized and com-
mences to cut out resistance. This solenoid, as already explained, cannot he
energized until one of the relays has operated its armature, and when this is done,
the controlling-circuit is closed to line at contact 26, which is independent of con-
act 54. This arrangement prevents the re-energizing of a relay after the circuit
has been broken, until the rheostat has cut in all the resistance.
The landing doors are provided with springs by which they are automatically
closed, and with latches 55 of ordinary character, which can be retracted from
either side of the door. There is an additional latch 56 in the door-iamb at each
landing, which locks the door. This latch is retracted automatically when the
car is opposite the landing by the engagement of a cam 57 on the car with the
cam-roller 58 which is mechanically connected with the latch.
The operation of the system is as follows:-
Let it be assumed that the elevator car is at the bottom of the shaft and that the
apparatus is all in initial or normal position with the circuits all oven. the throw-
over switch 32 closed to the landings system, the door-switches all closed and the

page_text: car empty. Assume that the push button, say on the third landing from the
bottom, is then closed. Circuit thereby closed through main switch 17 and
throwover switch 32, the locking magnets 35 on the various landings and the door-
switches 36 on the various doors, through the inner strand of the loop of wires
shown in Fig. 1 as connected to the car, through slack-cable switch 37, ear-gate
switch 39 and the outer strand of the loop of wires referred to, to the wire which
connects the switch-arms of the various push-buttons; thence through the push-
buttons on floor 3 to wire a,, across the contact of the floor-limit switch connected
therewith, through the coil of the up-relay U, across contacts 52 of the down-
relay D and across contacts, 54 of the rheostat to lead B. All of the locking-
magnets draw up their armatures 43, those on the 1st, 2nd and 4th floors, counting
from the bottom up, locking out their push-buttons; while at the third floor the
button is locked in. Thus interference between the different landings is pre-
vented. The armature of the up-relay is actuated and the main motor is iorth-
with connected to the source of supply through the following circuits: (a) The
armature circuit is from lead A through main switch 17, upper main limit
switch 50, up-relay contacts 18, through the armature of the motor, through
rheostat-coils 20, being the entire resistance thereof, and across contacts 21 of the
up-relay to lead B; (6) The field-coil 27, which is in shunt with the armature,
is connected with contact 26 of the up-relay. There is also a branch in parallel
with the field-coil branch, which includes a brake magnet coil 28 and a rheostat-
solenoid 29.
Thus it will be seen that as soon as a landing button is pushed in the brake is
lifted off the armature of the main motor, the armature and field coils are charged
and the rheostat begins to operate. The resistance of the rheostat is gradually
cut out and when it is all cut out the shunted switch 30 is opened and the resist-
ance 31 is thrown in with the field, thereby increasing the speed of the motor.
When the car reaches the third landing the contact 44 of the floor-limit switch
will be opened, causing the push-buttons to be released, the armature of the up-
relay to fall back, the motor to be instantly disconnected, the armature to be short-
circuited or close-circuited through contacts 23 of the two relays and resistance 24,
and the rheostat to return by gravity to normal position. The car comes to rest
and cannot be started again until rheostat-contact 54 is again closed, and all the
resistance is thrown into circuit with the motor-armature.
It will be clear from the foregoing how the car can be lowered or brought to
any floor; and that if by any chance two push-buttons should be closed simul-
taneously the car will go to the more distant landing and stop there and the
apparatus assume normal position; and that when one enters the car, the push-
buttons at the landings are all cut out.
In the foregoing apparatus and system there is a rheostat 20 and two directional
devices D and U which cannot be operated simultaneously nor when the rheostat
arm or contact block is in any other than initial position, closing contact 54.
And vice versa the rheostat arm can be moved away from initial position only
when and while one of the directional devices actuated, returning automatically
to initial position, as soon as the condition arises where neither directional device
is actuated. The push-buttons 33 or 34, or the car-push-buttons 38, which may
be calle master-switches or master-controller-buttons, can be opened at any
instant at will to bring the car to a stop at any point along the hoistway, by
causing the circuit to be opened at one of the relays. Thereafter nothing can be
done until the rheostat-arm has returned to initial position, closing contacts 54,
but if meanwhile a push-button is closed either for up or down movement, as soon
as contact 54 is closed the circuits are completed and the desired operation is
initiated.
It will be seen that in the system herein illustrated there is a separate set of
contacts operated by relays for both directions of motion. These relays, the
circuits controlling them, and the circuits which they establish between the
motor and the source of supply are distinguished, for convenience, by the terms

page_text: "up" and "down." But the circuits resulting from the operation of one relay
or the other, are in all respects similar except in direction, and since the system is
equally applicable to the control of other mechanism than elevators, it is not
intended to limit this invention to elevators and other mechanism in which there
is an up and down movement by the employment of these terms.
**
Many equivalent forms of apparatus may be substituted for these shown and
deser.bed in the foregoing drawings and specifications without departing from
the spirit of the invention, and the terms solenoid" and "relay" are to be con-
strued as covering any electrically operated device which may be substituted.
The substitution of a pilot-motor for the rheostat-solenoid is, for example, illus-
trated in my British Patent No. 4,549, dated February 23, 1898.
This patent also shows many other ways in which the invention here claimed
may be elaborated, as, for example, in the employment of repeating relays. The
terms of the claims are, therefore, to be broadly interpreted so as to include such
equivalent devices as are shown in this patent.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1. The combination of a source of current supply, a motor, a rheostat, contacts
for connecting the motor in a circuit with the source of supply, means for operat-
ing the rheostat, and means for preventing the connection of the motor to the
source of supply except when the rheostat is in normal position, substantially as
described.
2. The combination of a source of current supply, a motor, a rheostat, a set of
contacts for connecting the motor to the source of supply in one direction, a set
of contacts for connecting the motor to the source of supply in the opposite
direction, means for preventing the closure of either set of contacts after the circuit
has been opened until the rheostat is in normal position, substantially as described.
3. The combination of a motor, a rheostat, an up-circuit, a down-circuit, and
a resistance-controlling circuit, means for preventing the simultaneous closure
of both the up-circuit and the down-circuit, and means for preventing the closure
of either the up-circuit or the down-circuit except when the rheostat is in normal
position, substantially as described.
4. The combination of a source of current supply, a motor, contacts for con-
necting the motor to the source of supply, an up-relay and a down-relay for con-
trolling these contacts, an up-controlling circuit containing the up-relay coil and
a contact controlled by the down-relay, and a down-controlling circuit containing
the down-relay coil and a contact controlled by the up-relay; substantially as
described.
5. In an elevator system the combination of a motor, a source of current supply,
a resistance for the armature thereof, means for cutting out the resistance, means
for providing a strong field for the motor when first connected to the source of
supply, and means for weakening the field of the motor after the resistance in
the armature circuit has been cut out, substantially as described.
6. The combination of an electric circuit, a plurality of circuit-closing devices
in branches of the electric circuit, a locking-magnet in connection with each
circuit-closing device, mechanical connections between the magnet-armature and
the connected circuit-closing device whereby attraction of the magnet-armature
without simultaneous closure of the connected circuit closing-device will lock
the latter in open position, and connections whereby all the magnets are in
circuit with all the circuit-closing devices, substantially as described.
7. In an elevator system, the combination of a car, a controlling circuit, circuit-
closing devices in the controlling-circuit and located at the several elevator land-
ings, a car-gate hinged so as to fold into the car and located opposite the entrance
thereto, and a switch in the controlling-circuit and connected with the car-gate
so as to be opened when the gate is folded into the car, substantially as described.

page_text: 8. In an elevator system, the combination of a controlling-circuit, circuit-closing
devices in branches of the controlling circuit and located at the several elevator
landings, floor-limit switches in each branch of the controlling-circuit in series
with the circuit-closing devices, arms engaging with the floor-limit switches, a
shaft to which the arms are adjustably clamped, and means for rotating this shaft
synchronously with the movement of the elevator mechanism, substantially as
described.
9. In a rheostat comprising a solenoid and a resistance, a shunted switch in
circuit with the solenoid and constructed so as to be engaged by the plunger of
the solenoid when the rheostat is fully operated, and a contact in a branch from
the source of supply to the solenoid and constructed so as to be closed by the
plunger of the solenoid when the rheostat is returned to normal position, sub-
stantially as described.
Dated this 07th day of Wah 1900