Apparatus for Electrically Controlling the Hoisting Mechanism of Elevators or any other Type of Machinery.
Year: 1898

page_text: [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,
Manufacturer.]
Apparatus for Electrically Controlling the Hoisting Mechanism of
Elevators or any other Type of Machinery.
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:-
The improvements relate more especially to hoisting mechanism used in eleva-
tors and to the mechanism enployed in transmitting power to a winding drum
of a hoisting machine; they also relate to a particular construction of idler
sheaves, whereby these are carried from side to side so as to preserve them in
line with the points at which the ropes wind from the drum; they also relate to
safety devices in connection with the ropes and the drum, whereby any slacken-
ing of the ropes leading to the drum, or improper winding upon the drum,
will cause the opening of a switch and stop the mechanism; and they also relate
to an electrical system whereby, if the machinery is driven, as shown, by electric
motors, these motors are operated and controlled, which electrical system is
applicable to the control of motors without respect to the particular character
of the mechanism which the motors may be used to drive.
In the accompanying drawings, which form a part of this specification,
Figure 1 is a plan view showing the hoisting machine and vibrating idler
sheaves under which the cables are led to the counterweight; the safety devices
and the covers for the driving gears being omitted and the idler sheaves and
bevel gears being shown in section;
Fig. 2 is a side elevation showing the hoisting mechanism and idler sheaves;
the base of the machine being in section on the line of one of the worm-shafts,
and the outer bearing for the screw which supports the vibrating sheaves being
removed;
Fig. 3 is an elevation of the end of the hoisting machine at which the motors
are located;
Fig. 4 is a side elevation showing two slates and control-apparatus mounted
thereon;
Fig. 5 is a front view of one of these slates showing the pilot-motor, con-
tacts for shunt-armature resistances, brake-relay, throttle, stop-relay, speed-
relay, shunt-opener, controller-board operating switch, switch between controller-
board and car-operating switches, and main-line switch;
Fig. 6 is a front view of the other of these slates showing the contacts for
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page_text: breaker and the up-circuit
the series armature-resistance, the down-circuit
breaker;
Fig. 7 is a general diagram of the system of wiring, somewhat simplified;
Fig. 8 is a diagram showing the wiring of the shunt armature-resistances used
in practice;
Fig. 9 is a diagram showing the wiring of the series armature-resistances used
in practice;
Fig. 10 is a diagram showing the connections of two car-switches and a con-
troller-board switch.
The elevator car is directly balanced by a counterweight somewhat less in
weight than the car; and there is also provided a counterweight approximately
equal in weight to the average strain on the ropes leading from the car to the
drum.
HOISTING MECHANISM.
The hoisting mechanism consists of a winding drum 1 suitably mounted, and
driven by two motors 2 through the agency of worm gearing. The armature-
shafts of the motors are directly coupled to the worm-shafts 3 of the hoisting
mechanism. There are two worm-shafts, each connected to one of the motors.
Each worm-shaft is provided with two worms 4 which engage with worm-
wheels 5 mounted on two parallel worm-wheel shafts 67 which are geared
together by spur-gears 8. The drum is mounted upon one of the worm-wheel
shafts, the other shafts being added to balance the thrusts on the worm-shafts.
Each worm-shaft 3 carries a right-hand worm and a left-hand worm. Their
end thrusts are therefore always opposed to each other and completely balanced,
so that no thrust bearings are necessary on the shafts. The worms on the two
worm-shafts are reversed with respect to each other, so that a right-hand worm
on one shaft is opposite a left-hand worm on the other shaft. Since the worm-
wheels on the worm-wheel shafts 67 are cut right and left to engage with the
worms, it follows that the worm-wheels on each of these worm-wheel shafts will
also be reversed with respect to each other. Owing to the obliquity of the teeth
on the worm-wheels, they also have a thrust in the direction of their shafts, but
the thrusts of the two worm-wheels on each worm-wheel shaft are equal and
opposed to each other, so that no thrust bearings are needed on the worm-wheel
shafts.
The worm wheel shafts are coupled by two pairs of spur-gears. In order to
secure the perfect meshing of all the gears with respect to each other, at least
two of the spur-gears and two of the worm-wheels are not keyed fast to their
shafts when the machine is first assembled, but are bolted to flanges which are
keyed to the shafts. The bolts pass through oval holes in the gears, so that the
gears may slip around with respect to their shafts such slight amount as. may be
necessary to bring them into correspondence with the remaining gears. While
thus mounted, it is necessary to run the train of gearing for some time before
it is put into use, in order to allow the teeth to adjust and grind themselves
into correct relative spacing with respect to each other. When this has been
accomplished, the gears, which were at first held only by the bolts, are rigidly
secured by dowel pins.
In order that the cables may be carried horizontally from the hoisting machine
to the point where they rise in the well, either for the car or a counter-weight,
it is necessary to provide idler sheaves 9. To avoid leading the cables to the
idler sheaves obliquely these sheaves must be mounted so that they shall be
carried laterally as the cables wind or unwind from the drum. To do this there
is provided a threaded shaft 10 which is positively driven from the hoisting
machinery through the bevel gears 11, shaft 12, and bevel gears 13. The
threaded shaft engages two nuts 14, which are held against rotation by arms 15
engaging with a guide-rail 16. These nuts serve as bearings for the idler
sheaves. As shown, the shaft is provided with a right-hand and left-hand thread,
it being intended to carry two sheaves engaging with ropes which unwind from

page_text: right-hand and left-hand grooves on the drum. The parts which carry the
idler sheaves are mounted on a separate base from the hoisting-machine, and will
usually be at a greater distance than shown. The two pairs of bevel gears may
therefore be at a considerable distance from each other, and the connecting
shaft 12 will consequently have to be of such length as may be required.
car.
Two sets of cables are shown in connection with the hoisting-machine, each
consisting of four ropes, two of which lie adjacent in right-hand spiral grooves, -
and two adjacent in left-hand spiral grooves upon the drum. The ends of the
cables in one of these sets 17 are anchored adjacent to the flanges of the drum,
and, as shown, lead directly up from the drum, and are intended to lead to the
The ends of the cables in the other set 18 are anchored to the drum near
its middle plane, and lead under the idler sheaves, and are intended to lead to
the counterweight. This counter-weight is called the load-counterweight or the
drum-counterweight. The hoisting mechanism is provided with various devices
for stopping the machinery in event of the slackening of the winding ropes or
their overriding on the drum; for stopping and holding the machinery when the
car is stopped at intermediate points in its range of travel; for automatically
stopping the machinery at both the upper and lower limits of the range of travel
of the car; and for automatically stopping the machinery in event of excessive
speed of either motors or car.
The mechanical features of these devices will now be described, and their
electrical features will be described in connection with the general system of
wiring and electrical operation.
The device which is intended to stop the hoisting machinery in case the
cables should fail to wind properly upon the drum, or in case the cables which
lead to the car should become slack, consists of a switch in the motor-circuit,
called the slack-cable switch, its moveable arm 19 being mounted on a rock-
shaft 20. This switch arm is pivoted to an arm on the rock-shaft in such a
manner that it may be opened independently of any movement of the rock-shaft,
but will be forced open in case the rock-shaft is rotated. Depending from the
rock-shaft are arms 21 which carry a horizontal shaft 22 on which are idler
wheels 23 that bear against the cables leading from the drum. Weights 24 on
horizontal arms 25 from the rock-shaft cause these idler wheels to press against
the cables, and should the cables become slack, the rock-shaft will revolve a
sufficient distance to throw out the switch. Since the switch is independently
pivoted, the re-tightening of the cables, while it will return the rock-shaft to
its normal position, will not return the switch, and the latter will remain open
until closed by hand.
The parts operating in case of any of the cables failing to wind properly on
the drum are as follows: A bar 26 extends across the face of the drum, and in
such close proximity thereto that if any cable should at any point fail to wind
in the bottom of its groove, and either lie across the ridge which separates ad-
joining grooves, or on top of another turn of the cable, it will come in contact
with this bar and force it outward. This motion is transmitted through a vertical
rod 27 to the switch, and will throw it open.
The devices for stopping and holding mechanism after its speed has been
checked as much as practicable by the electrical arrangements, consist of strap-
brakes 28 engaging with drums on each of the worm-shafts. These brakes are
applied by heavy springs 29. When the hoisting machine is in motion, they
are held off by the straightening of toggles 30, which are connected to soft iron
plungers 31 that nearly meet in the center of a coil of wire. When a current
is passing in this coil of wire, the plungers are magnetized and attract each other,
thus holding off the brakes. But on the interruption of this current, the mag-
netism ceases in the plungers, and the springs instantly apply the brakes.
The devices for stopping the mechanism at the upper and lower limits of the
range of travel consist of a series of switches not shown in the mechanical figures.
which are so placed on the hoisting machinery that they will be engaged and

page_text: opened by a suitable projecting part of the machinery as it nears its range of
travel.
Each motor has connected to it a centrifugal governor, not shown, which is
constructed to open a switch that, will effect the stopping of both motors when-
ever the speed reaches that at which the governors are adjusted to open.
The car also carries a governor which operates mechanically to apply grips
between the car and its guides.
CONTROL SYSTEM.
The system of control being that of an overbalanced car, the drum counter-
weight balancing a portion of the maximum load, say, for convenience, balancing
the average load, the following unbalanced conditions of operation may arise:
The car and its load may be heavier than the counterweight, in which case the
car will drive the system, delivering energy to the motor if descending, or will
absorb energy from the motor if ascending; or the car and its load may be
lighter than the counterweight, in which case the counterweight will pay energy
to the system while the car is ascending, and will absorb energy while the car
is descending. Under proper conditions the system pays energy to the line.
The current for all the electrical circuits is led to the two leads A B through
a main switch 33, by which the entire system can be connected to or cut off
from the source of current supply. The leads A B are branched so that con
nection can be made with them at various points.
The electrical control is effected by turning the car-switch handle 34, which
is connected with the lead A, to contact plates through which the circuit can be
established in various branches of the system. These contacts lie on two con-
centric circles so that the switch can simultaneously close a circuit through a
contact plate in each circle. The contacts on the inner circle close circuits
which determine the direction of movement, and the contacts on the outer circle
close circuits which determine the speed of movement. The contacts and circuits
and the way in which they determine the direction will be discussed first.
CONTROL OF DIRECTION.
There are two contact plates 35 36 on the inner circle and these are so shaped
and positioned that contact will be made with one or the other as soon as the
switch is moved from its middle or stop position, and will be maintained through-
out the extent of movement of the switch. Wires lead from these contacts to
electro-magnet coils or solenoids 37 38 of two circuit breakers, the former being
the up-circuit-breaker which is operated when the car is to ascend, and the
latter being the down-circuit breaker which is operated when the car is to
descend. The coils of each circuit-breaker are in series with contacts 39 40
which are opened by the operation of the other circuit breaker so that one cannot
be lifted until the other has dropped. The coils of the up-circuit breaker are
connected in series with an upper-limit switch 41 and the coils of the down
circuit breaker are connected in series with a lower-limit switch 42. The course
of the current through the coil of either circuit breaker leads through a centri-
fugal governor switch 43 and a slack cable switch 44, through a stop-relay 45
and thence through a cut-out switch, which is closed when the parts are in
normal or initial position to the lead B. The stop-relay operates a circuit closer
and closes a contact 46 in a circuit around this cut-out switch to the lead B, so
that the stop-relay shall not be cut out of circuit by the subsequent opening of
the cut-out switch. The stop-relay also closes a second contact 47 which com-
pletes a circuit between the leads through the brake-coil 48, thereby releasing
the working motor.
The closure of the car-switch on the up-side causes the operation of the up-
circuit breaker. as stated, which connects the armature 49 of the working motor
to the leads A B by closing two sets of contacts 50 and 51, the contact 50 con-
necting the lead A to one brush of the armature through rheostat 52, called the

page_text: series resistance, and the other contact 51 closing the other brush through an
upper automatic circuit-breaker 53 to the lead B. In like manner operation of
the down-circuit breaker closes contacts 54 55 and connects the armature of the
working motor to the leads A B in the opposite direction, the connection to
the lead being through a lower-automatic switch 56. Since the field of the
working motor is not reversed, reversal of the current in the armature reverses
the direction of rotation thereof.
In addition to the connections to the leads, the working motor armature is
shunted through a rheostat 57 called the shunt-resistance. In the position in
which the parts are shown in the diagram and in which they remain so long
as the car-switch is moved only so far as above indicated, the line connection
is through the entire series-resistance and the motor armature is very nearly
short-circuited through the shunt. The armature will revolve slowly, and,
after attaining the full speed attainable in this position of the parts, will move
slowly but steadily so long as the car-switch remains in the position indicated,
namely, just closed. As it is intended that the system shall always be brought
into this position before stopping, the connections of the armature 49 after the
car-switch is opened will be described. Current is cut off from coils 37 or 38
and 45. The armature 49 will then be cut off from the line but will be closed
on itself through two contacts 58 59. The current generated by the armature
while moving under the momentum of the system will energize a brake-relay
coil 60 and cause it to hold up its armature and maintain a contact 61 which
closes a circuit through the coil of the brake-magnet 48 and an upper-limit
switch 62 and a lower-limit switch 63. The brake will 'thus be held off until
the armature comes to rest or passes the designed limits of motion, when con-
tact 61 is opened and the brake is applied. Meanwhile the working-motor's
field is weakened by resistance 63 thrown in on opening contact 63b.
CONTROL OF SPEED.
The effect of closing the car-switch at one of the speed-controlling contacts
will now be discussed. There are three pairs of these contacts, the two con-
tacts of each pair being connected together and disposed in corresponding
positions on the up-side and the down-side of the switch. On closing the switch
at either side thereof on the first speed-controlling contact 64 no effect is pro-
duced when the system is in normal or initial position, the wire which leads
from this contact being open at the full limit switch of the pilot-motor. If the
switch is carried further around and brought in contact with one of the second
or intermediate pair of speed-controlling contacts 65, a circuit is closed through
contacts 66, through a normally closed shunt 67 around a resistance-coil, through
a full-limit switch 68 operated by the pilot-motor and which is normally closed,
through a set of field-coils 69 of the pilot-motor, across the armature 70 of the
pilot-motor, through the coils of a brake-magnet 71 of the pilot-motor, and
thence to lead B. "This will release the pilot-motor and cause it to revolve. The
speed of the pilot-motor is adjusted by a resistance 72 which is connected across
the brushes thereof. It will be seen that there is a provision made for short-
circuiting the pilot-motor through this shunt under certain conditions which will
be explained hereafter. When the pilot-motor begins to revolve, the nuts upon
the screw-shaft thereof begin to travel. One of these 73 gradually cuts in the
shunt-resistance 57, and gradually cuts out the series-resistance 52; another
nut 74 operates certain switches as follows: Immediately on the starting of the
pilot-motor the full-off limit switch 75 is closed and then the cut-out switch 76 is
opened. The closure of the full-off limit switch brings the first pair of speed-control
contacts 64 of the car-switch into play. It will be seen that the first pair is
connected through this switch to a field-coil 77 of the pilot-motor, which the
current traverses in opposite direction to its direction in the field-coil 69 con-
nected with the second pair of contacts 65 of the car-switch. Under these con-
ditions it is possible to run the speed of the car up by leaving the car-switch in

page_text: contact with a contact 65 until the entire series-resistance 52 is cut out and the
entire shunt-resistance is cut in; or, to diminish the speed of the car by closing
the car-switch at a contact 64; or, having brought the car to some intermediate
speed, to let it run at that speed by holding the car-switch handle between the
two. contacts 64 65 and out of contact with both. These two pairs of speed-
contacts of the car-switch will be called the graduating contacts, the first pair 64
being the slack contacts, and the second the acceleration contacts. By operation
between these contacts under the conditions specified, the car can be brought
to the maximum graduated speed, or back to the slow speed, or kept running
steadily at any intermediate speed, but it cannot be stopped so long as the switch
is closed on either the up-side or the down-side. If the circuit is closed in the
car-switch at a contact 65 long enough to attain the maximum graduated speed,
the shunt-opener switch 78 is closed, thus completing a branch across the leads,
which includes the shunt-opener switch and the coils 79 of the shunt-opener 80,
and the shunt-resistance circuit is opened and held open at the shunt-opener.
A moment later the full-limit switch 68 is opened and the pilot-motor is brought
to rest.
a
The speed may be increased still further by closing at one of the third con-
tacts 81, called the full-speed contacts of the car-switch. The closure on
full-speed contact completes the circuit only in case the shunt-opener switch is
closed, that is, only after the maximum graduated speed has been attained. The
circuit is completed through the coil 82 of a speed-relay and the shunt-opener
switch 78. The coil of the speed-relay lifts its armature and opens a circuit-
closer 83 in a shunt around a field-resistance 84, which is thereby thrown in
series with the field 85 of the working-motor, weakening its field, and causing
the armature of the motor to speed up. The car will then attain the greatest
allowed speed and will continue to run at that speed until checked or brought
to a stop by the operation of the car-switch, unless some one of the safety or
limit switches is operated. Opening the car-switch at the full-speed contact
will cause the speed to drop to the maximum graduated speed. Closing the car-
switch on an intermediate or acceleration contact will produce no effect, but
closing the switch at the slack contact will cause the speed to fall gradually
toward or to the slow speed. Opening the car-switch entirely will then cause
the car to stop. Should the operator open the car-switch entirely suddenly,
without giving the pilot-motor time to return to initial position the various parts
which it operates, this result would be effected by the dropping of the armature
of the stop-relay 45 and closure of the normally closed circuit-breaker 86
operated thereby, which will close a branch from the lead A through this circuit-
breaker, through the full-off limit switch 75, and through the pilot-motor 77 70
and the coil of the brake-magnet 71 thereof to the lead B. The pilot-motor will
run until the switch 75 is opened.
There is also provided in series with the armature of the working-motor a
throttle 87 consisting of a few coils, which, should the armature be overloaded
from any cause, will close a circuit-closer 88, which short-circuits the armature
of the pilot-motor, at the same time opening the short-circuit 67 around a
resistance 89 in series with the field and armature of the pilot-motor, so as to
prevent excessive current. The short-circuiting of the armature will cause the
pilot-motor to stop. There will also he closed another circuit-closer 90 which
short-circuits the field-resistance 84, causing the field of the working-motor to
be increased, and thereby increasing the counter-electromotive force in the
armature.
In the general diagram of circuits but one working motor is shown for the
sake of simplicity. In practice the armatures of the two working motors are
connected in series in the lead where the armature 49 of one motor is shown
in the diagram and the fields of the two motors are in series with each other
and in shunt with the armatures in the lead where the field 85 of the motor is
indicated in the diagram.

page_text: The system is, in practice, provided with a switch for operating the car from
some point without the car, as well as from the car, for example, from a point
in the room where the driving mechanism is placed. This, as illustrated in
Fig. 10, is effected by providing in the line A, where it is led to the car switch,
a two-way switch 91, which will send the current to the car-switch, or to the
auxiliary switch 92, as desired. The construction and operation of the auxiliary
switch is the same as that of the car-switch.
It is frequently desirable in practice to have two switches on the car, as, for
example, where the car has more than one entrance. In order to provide for
this, two car switches are shown in Fig. 10, the two being identical in construc-
tion and operation with the car-switch already explained, except that each
switch is provided with two contacts 93 94 at the neutral position, which are
bridged by the handle when the handle is at the neutral position. One contact
of each of these pairs of contacts is connected to the line A, and the other con-
tact of each pair is connected to the handle of the other switch. Each switch
can, therefore, operate the system, if the other is closed, but the circuit through
one of the switches is broken by undertaking to operate the other switch.
Two separate rheostats are used for the shunt-resistance and the series-resistance
connected with the armature of the working motor. The rheostat-arms 95 96
are mounted upon the same shaft 97, the heads of the arm 95 of the shunt-
resistance being properly insulated therefrom, but connected to each other by
a wire 98. The two rheostats are preferably constructed of the same number of
resistance grids or coils, but the effective resistance of the shunt-resistance should
be several times larger than that of the series-resistance. This is effected by
mounting the resistances of each set in two banks insulated from each other,
and properly connecting the banks to the line. The shunt-resistance has the
end of each bank upon which the arm rests when at zero-position connected up
to the line. The series-resistance has the rheostat arm and two adjacent ends of
the two banks connected to the line, alternate ends of the banks being electri-
cally connected by wires 99 100. The rheostats are each provided with two sets
of studs which are arranged in concentric arcs of circles. These studs are
placed so that the break between adjacent studs of each set is overlapped by a
stud of the other set. Each overlapping stud has two grids attached to it, the
grids being attached at their other ends, one to each of the studs overlapped.
Each head of the arms of the rheostats has spring-controlled contact fingers or
trailers 101 bearing upon the contact-blocks.
The motion of the arms is rotary, and not linear, as shown in the diagram of
circuits, Fig. 7. In addition to the contact-arms there are two switch-operating
arms (see Fig. 5), one 102, to operate the full-off limit and cut-out switches and
the other 103 to operate the full-on limit and the shunt-opener switches. The
full-off limit switch is closed before the cut-out switch is opened, and the shunt-
opened switch is closed before the full-on limit switch is opened. These are all
snap-switches.
Each of the circuit-breakers is made up of a yoke 104 forming a closed magnetic
circuit with an interior projection which pentrates a coil 37 or 38 placed within
the magnetic circuit. The circuit-closers are operated by a plunger-armature 105,
which passes through a collar on the yoke and is sucked into the coil when
current passes therethrough. Each contact is provided with a magnetic blow-
out 106 and with auxiliary carbon contacts 107 which are closed before and
opened after the regular metallic contacts, thus keeping them clean and bright.
The detailed illustrations of the other circuit-closers show the contacts some-
what differently disposed from the disposition shown in the diagram of circuits,
Fig. 7, but not differing essentially therefrom. These and the car and other
switches are readily understood from the drawings, and need no special
description.
"
For the sake of making the statements more definite and clear, the words "up
and "down" and words of like import have been used, these being the directions

page_text: in which elevators are run. But these words are not intended to limit the appli-
cation of the invention to the operation of cars in a vertical shaft.
Dated this 22nd Februar 1898
Apparatus for Electrically Controlling the Hoisting Mechanism of
Elevators or any other Type of Machinery.
I, HENRY HARINGTON LEIGII, 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 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 trans-
lating devices such as a motor or group of motors, used to drive an elevator, or
for other purposes. The motors are to run in either direction, at speeds con-
trollable within certain limits. They are called upon to maintain any desired
speed while running against any load up to their full capacity, and may be called
upon to hold their speed when connected to machinery that drives them and
causes them to act as generators.
The invention consists in providing for the motors controller-mechanisms,
which are controlled from the car by an operator's or master, or governing switch,
the controller-mechanism of any system being brought by the operator's switch
into such definite relations to the motor as to secure different speeds of the motor,
by closing the operator's switch at any one of several contacts. These relations
will be called "speed-relations" of the controller-mechanism to the motor. Pilot-
mechanism is provided for running the controller-mechanism, or a part of it,
and circuit openers are provided for opening the circuit of the pilot-mechanism
automatically or independently of the operator's switch, when the controller has
been brought into that speed-relation to the motor which closure of the appro-
priate contact of the operator's switch is intended to establish. And the circuits
are so arranged that the controller mechanism cannot be operated from initial
position toward full working position, corresponding to the fastest speed of the
elevator, without bringing the controller-mechanism first into a relation with
the motor corresponding to an intermediate speed of the motor. This is because
means are provided for bringing the contact of the operator's switch, which
corresponds to full speed of the motor, into operative relation when the con-
troller-mechanism attains the intermediate speed-relation. The restoration of
the controller-mechanism to initial relation may be effected, however, by closing
the operator's switch at a stop-contact, or by opening it, without respect to its
position at the moment that it is open, means being provided for automatically
restoring the controller-mechanism to initial position. This means for restoring
the controller to initial position acts independently of the operator's switch, and
therefore automatically in this sense, that after the circuit is once opened at
the operator's switch or elsewhere, or upon any failure of the current, the
operator's switch loses control of the system and the controller is restored to
initial position, no matter how the operator may manipulate his switch. When
the controller is restored to initial position the operator's switch is again restored
to control. This is effected by a circuit opener operating with the controller and
a bridging contact, magnetically operated in conjunction with the cut-out switch,
hereafter described fully.

page_text: The general method of controlling the speed of the main motor is to obtain
an intermediate speed by connecting the motor to the source of supply through
a rheostat and cutting resistance out from the circuit of its armature; the motor
armature being shunted when so connected by a resistance which is increased
while the resistance in the line is decreased; the shunt being finally opened.
Full speed is obtained by decreasing the field strength of the motor, after the
resistance in the armature circuit has been reduced.
Too rapid a change in the strength of the current in the main motor is pro-
vided against by the introduction of a throttle, which controls the speed of the
controller, preferably by controlling the current delivered to the pilot motor
which moves it. And too large a current is also provided against by strengthen-
ing the field of the main motor.
And with these various elements forming the system here described, is com-
bined a brake for the main motor, and provision for holding the brake off, pre-
ferably by means of the current generated by the main motor itself, while the
main motor is slowing down after the circuit has been opened.
In addition to the foregoing, the invention consists in details of construction
of the apparatus hereinafter described.
In the drawings left with the Provisional Specification which form a part of
this specification,
Figure 1 is a plan view showing a hoisting machine and vibrating idler sheaves
under which cables are led to a counterweight; the idler sheaves and bevel
gears being shown in section;
Fig. 2 is a side elevation showing the hoisting mechanism and idler sheaves;
the base of the machine being in section on the line of one of the worm-shafts,
and the outer bearing for the screw which supports the vibrating sheaves being
removed;
Fig. 3 is an elevation of the end of the hoisting machine at which the motors
are located;
Fig. 4 is a side elevation showing two slates and control apparatus mounted
thereon;
lig. 5 is a front view of one of these slates showing the pilot motor, con-
tacts for shunt armature resistances, brake-relay, throttle, stop-relay, speed-
relay, shunt opener, controller-board operating switch, switch between the con-
troller-board and car operating switches, and main line switch;
Fig. 6 is a front view of the other of these slates showing the contacts for the
series armature-resistance, the down-relay and the up-relay;
Fig. 7 is a general diagram of the system of wiring somewhat simplified;
Fig. 8 is a diagram showing the wiring of the shunt armature resistances used
in practice;
Fig. 9 is a diagram showing the wiring of the series-armature resistances used
in practice;
Fig. 10 is a diagram showing the connections of two car-switches and a con-
troller-board switch.
The elevator car is directly balanced by a counterweight somewhat less in
weight than the car; and there is also provided a counterweight approximately
equal in weight to the average strain on the ropes leading from the car to the
drum.
HOISTING MECHANISM.
The hoisting mechanism, although shown and described herein, is not here
claimed, since it is shown and claimed in another application, No. 30,923, dated
31 December, 1897.
The hoisting mechanism consists of a winding drum 1 suitably mounted, and
driven by two motors 2 through the agency of worm-gearing. The armature
shafts of the motors are directly coupled to the worm-shafts 3 of the hoisting
mechanism. There are two worm-shafts, each connected to one of the motors.
Each worm-shaft is provided with two worms 4 which engage with worm-

page_text: wheels 5 mounted on two parallel worm-wheel shafts 67 which are geared
together by spur-gears 8. The drum is mounted upon one of the worm-wheel
shafts, the other shaft being added to balance the thrusts on the worm-shafts.
Each worm-shaft carries a right-hand worm and a left-hand worm. Their
end thrusts are therefore, always opposed to each other and completely balanced,
so that no thrust bearings are necessary on the shafts. The worms on the two
worm-shafts are reversed with respect to each other, so that a right-hand worm
on one shaft is opposite a left-hand worm on the other shaft.
In order that the cables may be carried horizontally from the hoisting machine
to the point where they rise in the well, either for the car or a counterweight,
are provided idler sheaves 9. These sheaves must be mounted so that they shall
be carried laterally as the cables wind or unwind from the drum. To do this
there is provided a threaded shaft 10 which is positively driven from the hoist-
ing machinery through the bevel gears 11, shaft 12, and bevel gears 13. The
threaded shaft engages two nuts 14, which are held against rotation by arms 15
engaging with a guide-rail 16. These nuts serve as bearings for the idler-sheaves.
As shown, the shaft is provided with a right-hand and a left-hand thread, it
being intended to carry two sheaves engaging with ropes which unwind from the
right-hand and the left-hand grooves on the drum. The parts which carry the
idler-sheaves are mounted on a separate base from the hoisting machine, and
will usually be at a greater distance than shown. The two pairs of bevel gears
may therefore be at a considerable distance from each other, and the connecting
shaft 12 will consequently have to be of such length as may be required.
Two sets of cables are shown in connection with the hoisting machine, each
consisting of four ropes, two of which lie adjacent in right-hand spiral grooves,
and two adjacent in left-hand spiral grooves upon the drum. The ends of the
cables in one of these sets 17 are anchored adjacent to the flanges of the drum,
and, as shown, lead directly up from the drum, and are intended to lead to the
car. The ends of the cables in the other set 18 are anchored to the drum near
its middle plane, and lead under the idler sheaves, and are intended to lead to
the counterweight. This counterweight is called the load-counterweight or the
drum counterweight. The hoisting mechanism is provided with various devices
for stopping the machinery in the event of the slackening of the winding ropes or
their overriding on the drum; for stopping and holding the machinery when the
car is stopped at intermediate point in its range of travel; for automatically
stopping the machinery at both the upper and lower limits of the range of travel
of the car; and for automatically stopping the machinery in event of excessive
speed of either motors or car.
The mechanical features of these devices will now be described, and their
electrical features will be described in connection with the general system of
wiring and electrical operation.
The device which is intended to stop the hoisting machinery in case the
cables should fail to wind properly upon the drum, or in case the cables which
lead to the car should become slack, consists of a switch in the motor circuit,
called the slack-cable switch, its movable arm 19-being mounted on a rock-
shaft 20. This switch arm is pivoted to an arm on the rock-shaft in such a
manner that it may be opened independently of any movement of the rock-shaft,
but will be forced open in case the rock-shaft is rotated. Depending from the
rock-shaft are arms 21 which carry a horizontal shaft 22 on which are idler
wheels 23 that bear against the cables leading from the drum. Weights 24 on
horizontal arms 25 from the rock-shaft cause these idler wheels to press against
the cables, and should the cables become slack, the rock-shaft will revolve a
sufficient distance to throw out the switch. Since the switch is independently
pivoted, the retightening of the cables, while it will return the rock-shaft to
its normal position, will not return the switch, and the latter will remain open
until closed by hand.
The parts operating in case of any of the cables failing to wind properly on

page_text: the drum are as follows: A bar 26 extends across the face of the drum, and in
such close proximity thereto that if any cable should at any point fail to wind
in the bottom of its groove, and either lie across the ridge which separates ad-
joining grooves, or on top of another turn of the cable, it will come in contact
with this bar and force it outward. This motion is transmitted through a vertical
rod 27 to the switch, and will throw it open.
The devices for stopping and holding the mechanism after its speed has been
checked as much as practicable by the electrical arrangements, consist of strap-
brakes 28 engaging with the drums on each of the worm-shafts. These brakes are
applied by heavy springs 29. When the hoisting machine is in motion, they
are held off by the straightening of toggles 30, which are connected to soft iron
plungers 31 that nearly meet in the center of a coil of wire. When a current
is passing in this coil of wire, the plungers are magnetized and attract each other,
thus holding off the brakes. But on the interruption of this current, the mag-
netism ceases in the plungers, and the springs instantly apply the brakes.
The devices for stopping the mechanism at the upper and lower limits of the
range of travel consist of a series of switches not shown in the mechanical figures,
which are so placed on the hoisting machinery that they will be engaged and
opened by a suitable projecting part of the machinery as it nears its range of
travel.
Each motor has connected to it a centrifugal governor, not shown, which is
constructed to open a switch that will effect the stopping of both motors when-
ever the speed reaches that at which the governor is adjusted to open.
The car also carries a governor which operates mechanically to apply grips
between the car and its guides.
CONTROL SYSTEM.
The system of control being that of an overbalanced car, the drum counter-
weight balancing a portion of the maximum load, say, for convenience, balancing
the average load, the following unbalanced conditions of operation may arise:
The car and its load may be heavier than the counterweight, in which case the
car will drive the system, delivering energy to the motor if descending or will
absorb energy from the motor if ascending; or the car and its load may be
lighter than the counterweight, in which case the counterweight will pay energy
to the system while the car is ascending, and will absorb energy while the car
is descending. Under proper conditions the system pays energy to the line.
The diagram, Figure 7, shows the system of control applied to a shunt-wound
motor, the arrangement being such that the armature of the motor can be con-
nected to and disconnected from a suitable source of current supply, so that the
current will pass through the armature in either direction as may be required,
while the field of the motor is connected to the source of supply in the same
direction. The control of the motor is effected by suitably controlling the current
through its field and its armature, by the introduction of resistances into their
circuits and by shunting the armature, and by an electrically controlled brake.
The circuits of the armature, field and brake are under the control of an operator's
or master switch, which is located in the car, and also called the car switch,
and various regulating and safety devices, which act through suitable relay
apparatus.
The current for all of the electrical circuits is led from a suitable source of current
supply to two conductors A B through a main switch 33, by which the entire
system can be connected or disconnected. The conductors A B are branched
so that connection can be made with them at various points. The switch-arm 34
of the operator's switch is connected with the lead A, and traverses contact
plates on two concentric circles, so that circuits can be simultaneously closed at
a contact plate on each circle. The contacts on the inner circle close circuits
which determine the direction of movement of the motor, and the contacts on
the outer circle close circuits which determine its speed of movement.
circuits for determining direction will first be considered.
The

page_text: CONTROL OF DIRECTION.
There are two contacts 35 & 36 on the inner circle, which are so placed that
the switch will be closed through one or the other according as the switch arm
is moved in one direction or the other from the middle position, which it takes
when the switch is open. This closure through one contact or the other is main-
tained throughout the extent of movement of the switch arm in either direction
from its middle position. Wires lead from these contacts to relay-coils 37 & 38,
one of which controls a set of contacts for connecting the motor to the source of
supply in one direction, and the other of which controls a set of contacts for
connecting the motor with the source of supply in the opposite direction. Each
relay coil is in series with contacts (39 or 40) each of which is opened by the
operation of the other relay than the one with the coil of which it is in series,
so that one relay-coil cannot be energized if the other relay coil is energized and
its armature lifted, so that one cannot be lifted until the other has dropped and
both relays cannot operate simultaneously.
The coils of the up-relay are connected in series with an upper-limit switch 41
and the coils of the down-relay are connected in series with a lower limit
switch 42. The course of the current through either relay coil leads through a
centrifugal-governor switch 43 and a slack-cable switch 44, through a stop-
relay 45 and thence through a cut-out switch, which is closed to lead B when
the parts are in normal or initial position. The stop-relay upon operating its
armature, closes a contact 46 in a circuit through its coil and around this cut-
out switch to the lead B, so that the stop-relay shall not be cut out of circuit
by the subsequent opening of the cut-out switch. The stop-relay also closes a
second contact 47 which completes a circuit between the leads through the brake-
coil 48, thereby releasing the main motor.
The leads from the armature terminals of the main motor have a number of
branches through which the armature circuit may be established. When neither
of the relays 37 or 38 is energized, the motor is closed upon itself across two pairs
of contacts 58 and 59, which are in series with each other. The pair of con-
tacts 58 is controlled by the relay 37 and is opened by the operation of this relay.
The other pair of contacts 59 is controlled by the relay 38, and is opened by the
operation of this relay. This circuit is therefore opened upon the energizing
of either relay, and is closed when both relays are de-energized. On the opera-
tion of relay 37 through the closure of the operator's switch at the contact-
plate 35, one branch of one of the leads from the main motor armature 49 is
connected through a pair of contacts 50 to lead A, and the branch of the other lead
from the armature is connected through a pair of contacts 51 through an upper
automatic switch to lead B. In like manner, on the operation of relay 38,
through the closure of the operator's switch at the contact plate 36, one of the
leads from the armature is connected through a pair of contacts 54 to lead A,
and one branch of the other lead from the armature is connected through a pair
of contacts 55 to lead B. These relays connect the leads from the motor-armature
to the leads A and B of the source of supply in the opposite directions, the con-
nections to the lead B being through a lower automatic switch 56. The connec-
tions effected by one relay cause the motor to revolve in one direction, and the
connections effected by the other relay cause the motor to revolve in the opposite
direction.
The field coil of the motor is permanently connected to the leads A and B,
but when the parts are in the position of rest shown in the diagram, there is a
field resistance 63" in series with the field coil to save current. Around this
resistance are two shunts 63, one of which is closed when the relay 37 is
energized, and the other of which is closed when the relay 38 is energized. The
operation of either relay consequently cuts out this resistance and causes the
field to rise to its full strength.
Immediately on the energizing of either relay 37 or 38 the armature of the
motor is connected to the leads of the source of supply through the resistances 52

page_text: of the rheostat. At the same time the armature is shunted through another
branch in which shunt-resistances 57 can be cut in. Under these conditions,
the armature will revolve slowly.
The system is always brought into this position before stopping, and upon
opening the operator's switch, current is cut off from the coils 37 or 38 and 45.
The armature 49 will then be cut off from the line but will be closed on itself
through two contacts 58 59. The current generated by the armature while
moving under the momentum of the machinery will energize a brake relay coil 60
and cause it to hold up its armature and maintain a contact 61 which closes a
circuit through the coil of the brake magnet 48 and an upper-limit switch 62
and a lower-limit switch 63. The brake will thus be held off until the armature
comes to rest or passes the designed limits of motion, when contact 61 is opened
and the brake is applied. Meanwhile the motor field is weakened by resis-
tance 63 thrown in on opening contact 63b.
CONTROL OF SPEED.
The effect of closing the car switch at the various speed-controlling contacts
will now be discussed. The speed of the main motor is controlled by apparatus
which is called broadly controller-mechanism. This embraces a controller, which
comprises resistances included in the armature circuit of the main motor and in
the shunt around the armature circuit of the main motor when the
main motor is connected to the source of supply. The controller is
provided with suitable pilot mechanism for moving it, as, for example,
a pilot motor, with proper limit and other switches to control the
movement of the pilot motor, and therefore of the controller. In
addition to the resistances, there is also provided contacts for opening the shunt
around the main motor. The controller" mechanism also embraces, in addition
to the controller, a magnetic device for increasing the resistance in the field
circuit of the main motor, and a suitable switch operated by the pilot motor in
conjunction with the controller, which is closed after the controller has reached
or approached the limit of its motion from initial position. The main motor is
controlled from the operator's switch on the car through the controller mechanism,
and, in addition to the directional contacts already discussed, is provided with
certain speed-contacts, the effect of closure of which in different conditions of
the controller-mechanism will now be discussed.
Closure of the operator's switch at a speed contact, as hereafter more fully and
definitely explained, brings the controlling mechanism into a definite speed rela-
tion with the main motor. By this is meant that the load being the same, the
main motor will attain a definite speed, when the operator's switch is closed at
one contact and the controlling mechanism has been brought into the condition
set up by such closure of the operator's switch.
There are three pairs of speed contacts. The two contacts of each pair are
connected together and disposed in corresponding positions on the two sides of
the switch. The closure of the switch at one side or the other on the first of
these contacts 64 produces no effect if the system is in its initial position, since
the circuit leading from this contact is opened at the full-off limit switch 75
controlled by the pilot motor and the controller. This first pair of contacts is
used only in returning the controller toward position to slow down or stop the
main motor. The closure of the switch at one of the second or intermediate con-
tacts 65, which is used for bringing the controller mechanism to an intermediate
speed relation with the main motor, closes a circuit through the contacts 31 of
the stop-relay, through the shunt 67, which is normally closed across a resistance 89,
through a full-on limit switch 68 controlled by the pilot motor, which is closed,
except when the controller is at the full-on limit of its movement through a set
of field coils 69 of the pilot motor, then through the armature 70 of the pilot
motor, and the coils of a brake-magnet 71 of the pilot-motor, and thence
to lead B. This will release the pilot-motor and cause it to revolve. The speed

page_text: of the pilot-motor is adjusted by a resistance 72 which is connected across the
brushes thereof. It will be seen that there is a provision. made for closing the
pilot-motor on itself through this shunt under certain conditions which will be
explained hereafter. The pilot-motor in revolving, causes the contact block 73
and the nut 74 to travel along its threaded shaft. The contact block gradually
cuts in the shunt-resistance 57, and gradually cuts out the series-
resistance 52. The nut 74 throws certain switches as follows: Immedi-
ately on the starting of the pilot-motor, the full-off limit switch 75 is
closed and then the cut-out switch 76 is opened. The closure of the full-off limit
switch makes it possible to close a circuit through either of the first pair of speed-
control contacts 64 of the operator's switch. It will be seen that the first pair is
connected through this switch to a field coil 77 of the pilot-motor, which the
current traverses in opposite direction to its direction in the field-coil 69 con-
nected with the second pair of contacts 55 of the operator's switch. Under these
conditions, it is possible to increase the speed of the car by leaving the switch in
contact with a contact 65 until the entire series-resistance 52 is cut out and the
entire shunt resistance 57 is cut in, and the motor will thereby be speeded up.
Closure now of the operator's switch at either of the contacts 8.1 will energize
field-coil 69 of the pilot-motor, which is connected to the circuit oppositely to
coil 79. This will reverse the pilot-motor and cut in the resistance 52 of the
rheostat, and cut out the shunting resistances 57, and the main motor will thereby
be slowed down. If the operator's switch is held on either pair of contacts 64
or 65 for a length of time insufficient for the pilot-motor to move the controller
through the entire extent of its movement, and throw its limit switches, and
the operator's switch is then opened at the speed-contacts but held closed at one
of the directional contacts, the contact block will be left in an intermediate
position, and the main motor will run at corresponding speed. These contacts 64
and 65 are termed speed-controlling contacts, since closure at one or the other
enables the speed of the main motor to be graduated. The motor, however, is
not stopped by contact at either speed-contact, so long as the circuit is maintained
at either of the direction-controlling contacts. If the circuit is closed at the
contact 65 of the operator's switch for a sufficient time, the pilot-motor will run
until it closes the shunt-opener switch 78, and then automatically interrupts
its own circuit at the full-on limit switch, and stops further forward movement
of the controller.
The closure of the shunt-opener switch completes a circuit which includes
the coil 79 of the shunt-opener 80 and the shunt circuit is opened and held open.
It will thus be seen that the shunt is varied by changing its resistance and by
opening and closing it. The foregoing operation establishes a definite speed
relation between the controller-mechanism and the main motor.
A further increase of speed of the main motor is effected on closing the
operator's switch at one of the third pair of speed-contacts 81, which may be
termed the full-speed contacts. The circuit is through the coil 82 of the speed-
relay 83. This relay opens a shunt around a resistance 84, which is in series
with the field-circuit of the motor, thus decreasing the field-strength of the main
motor and causing the motor to speed up. This is another definite speed-relation
between the controller-mechanism and the main motor. This second-named
definite speed relation cannot be established until after the controller has been
fully operated and the first-named definite speed relation has been attained by
the controller-mechanism. This is because the full-speed contacts of the operator's
switch are not brought into operative relation with the system, nor can the field-
strength of the main motor be diminished, until, by the closure of an intermediate
speed contact of the operator's switch, the controller is operated and closes the
shunt-opener switch 78.
It will be seen that the switch 68, which is operated by the motor-controller,
constitutes, either alone or in combination with the intermediate speed-contacts

page_text: of the operator's switch, a set of contacts which are so arranged that the circuit
of the armature of the pilot motor is automatically interrupted only after it has
made a predetermined number of revolutions, and the switch 78, either alone
or in combination with the full-speed contacts of the operator's switch, con-
stitutes a second set of contacts which are brought into operative relation as soon
as, and in practice slightly before, the circuit of the first set of contacts is
interrupted.
In series with the circuit through the armature of the main motor is a coil 87
of a throttle, the coil consisting of a few turns of the heavy wire which con-
ducts the armature-current, and is therefore dependent in its operation upon the
strength of the current in the main circuit. This throttle is so adjusted that in
event of the current through the armature rising above a safe amount, the
circuit of the pilot mechanism is shunted. This is effected by closing con-
tacts 88, which short-circuit the armature of the pilot motor. At the same
time the contacts 67 will be opened and the resistance 89 will be cut into the
pilot-motor circuit, thus decreasing the current through the pilot-motor. Thus
movement of the controller is checked or arrested. The operation of the
throttle also closes contacts 90 which cut out the resistance 84 of the field-coil
of the main motor, in event of its having been cut in by the speed-relays, and
thereby insures a strong field to oppose the excessive current in the armature of
the main motor.
If while the motor is connected to the source of supply, the operator's switch
be opened, thus opening the controlling circuit, or the circuit be opened at any
other point, or the current fail from any cause, the stop-relay will at once drop
its armature. This will also open the circuit at the contacts 46. Control is
thus taken away from the operator's switch, and it cannot be restored until the
controller-mechanism is restored to its initial position and closes the circuit at
the cut-out switch 76. Upon the interruption of the controlling circuit, the
relay-armature by which the motor-armature is connected to the source of supply
is at once dropped, and the motor-armature is disconnected and is closed upon
itself across the contacts 58 and 59 through the resistance 52 of the rheostat.
The armature of the stop-relay, upon dropping, closes contacts 86 and establishes
a circuit through the pilot motor, which effects the return of the controller-
mechanism to its initial position, independently of any manipulation of the
operator's switch, and therefore automatically. Immediately on the controller-
mechanism starting back, it opens the circuit of the shunt-opener coil at the
shunt-opener switch 78 and the shunt-opener drops its armature, thus closing
through the shunt-resistances 57 a second shunt to the motor-armature. The
return of the controller-mechanism cuts out the resistances 52 and 57 in the
two shunts, and slows down the motor. A portion of the current generated in
the motor-armature while it is slowing down passes through a brake-relay coil 60,
thereby causing it to attract its armature, and to close at the contacts 61, a
circuit through the brake coil. Thus the brake is held off by means operated
with current generated by the motor, and is delayed until the motor-armature
has nearly come to rest.
It is obvious that the brake is controlled from the operator's switch in com-
bination with the controller and the cut-out switch and the bridging contact
and other means whereby control is taken away from the operator's switch and
the controller is restored to its initial position. The operation of these parts has
already been fully explained, and it is sufficient at this point to call attention
to the fact that the brake co-operates with them in the operation of the system.
In applying the system of control to a motor which is used to run an elevator,
it is important that there should be automatic devices for stopping the
mechanism when the car approaches both the upper and lower limits of travel.
For this purpose arms are provided which are geared to and move synchronously
with the elevator mechanism. These are so arranged and adjusted that they

page_text: engage and open a series of switches when the car nears either limit of travel.
Thus if the relay coil 37 is energized when the elevator is descending, there will
be placed in circuit with it a switch 41, which will be opened as the lower limit
of travel is approached, and in circuit with the relay coil 38 will be the switch 42,
which will be opened as the upper limit of travel is approached. Opening either
of these switches effects the stoppage of the motor in the same way as opening
the circuit at the operator's switch. The relay coil 37 or 38 is de-energized and
drops its armature, thus instantly disconnecting the armature of the main motor
from the source of supply and closing it upon itself. At the same time the brake-
relay coil 60, through which the brake is held off, is cut off from the source of
supply, but current generated in the motor is still permitted to pass through this
coil, so that the brake will not be applied until the motor comes to rest. These
two limit switches in the two branches of the controlling circuit are sufficient
to stop the elevator at its limits of travel, provided that the control-apparatus is
in proper working condition. But as an additional precaution, extra limit
switches 53 and 56 are included in the main circuits of the motor armature, to
insure the opening of these circuits in event of the armatures of the relay coils
failing to drop when they are deenergized. There is also a third set of limit
switches 62 and 63 which are opened to insure the application of the brake.
These switches are opened after the switches in the controlling-circuit.
In the controlling-circuit there is also a switch 43 which is opened by a centri-
fugal governor, and a switch 44 which is opened in event of the hoisting ropes
becoming slack or failing to wind properly.
Before describing the details of construction of the apparatus used, it may be
pointed out that many changes may be made in the foregoing arrangements
without departing from the spirit of the invention. For example, a controller
might be arranged which can be restored to its initial position by moving on in
the same direction as it moves from the initial position, instead of, as shown,
returning over the path it has traveled from the initial position. Moreover,
the controller might be arranged to move to various definite positions, one in
advance of the other, when the operator's switch is closed at successive contacts;
instead of having but one stage of movement of the controller, and then, as
shown, operating some other device which forms a part of the controller-mech-
anism. And the controller might be used to control a plurality of motors by
changing the connections thereof relatively to each other. Many other changes
can be made, as will readily be seen.
Referring now to the details of construction of the apparatus, Figures 4 to 6
show the various parts of the control-apparatus as this is preferably constructed.
These parts are attached to two slates which are connected together in parallel
position by stay-rods. The various relays are in the form of solenoid coils which
are set in iron yokes 104 and when energized attract iron plungers 105 which
pass through openings in the yokes into the coils. Insulated contact bars carried
by the plungers make the contacts for the heavy currents with copper springs
and carbon blocks 107, which are connected together. The carbon blocks are
carried in spring-pressed holders which have a slight movement in the direction
in which contact is made and broken, so that when contact is broken the carbon
will follow the contact bar and maintain contact until it has separated from the
copper springs. The final break of the contact is therefore always at the carbon
blocks. The break is made between the poles of the blow-out magnets 106.
Figure 10 shows how three operator's switches may be provided so that the
control apparatus can be operated from either one of the switches, conflicting
circuits through the other switches being prevented. Thus there is a throw-
over switch 91 in the circuit between the lower of the three operator's switches
and the upper two. The upper switches cannot mutually interfere, since the
circuit to each includes contacts 93 and 94 of the other, which are closed while an
operator's switch is in its normal open position, but is open in
thereof.
other position
every

page_text: Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what I
claim is:-
-
1. The combination of a source of supply, a motor, controller-mechanism
therefor, embracing a controller, pilot mechanism for the controller, a set of
contacts for controlling the pilot-mechanism, so arranged that the circuit of the
pilot-mechanism is automatically interrupted after the controller has come to a
predetermined position, an operator's switch having a plurality of contacts,
ineans for bringing the controller to the said predetermined position by closing
at one of the contacts of the operator's switch, and means for bringing the con-
troller-mechanism to a different speed-relation with the motor by closing at
another of the contacts of the operator's switch, substantially as described.
2. In a system of control for electric motors, the combination of a motor-
controller, a pilot motor for driving the motor-controller, a set of contacts for
regulating the pilot motor, which are so arranged that the circuit with the arma-
ture of the pilot motor is automatically interrupted only after it has made a pre-
determined number of revolutions, and a second set of contacts which are brought
into operative relation as soon as the circuit of the first set of contacts is inter-
rupted, substantially as described.
3. The combination of a motor, a source of supply, means for connecting the
motor to the source of supply, a shunt around the motor, a controller for the
motor, and means for opening the shunt when the controller is brought to a
predetermined position, substantially as described.
4. The combination of a motor, controller-mechanism therefor, an operator's
switch for operating the controller-mechanism, a cut-out switch opened when
the controller-mechanism is moved from initial position, a bridging contact for
closing the circuit around the cut-out switch, means for opening the bridging
contact when the circuit is opened, thus taking control from the operator's
switch, and means for restoring the controller to initial position and closing
the cut-out switch independently of the operator's switch, thus restoring control
to the operator's switch, substantially as described.
5. The combination of a motor, a controller therefor, an operator's switch,
means connected therewith for operating the controller, a throttle which varies
the operation of the controller independently of the operator's switch, means for
restoring the controller to initial position independently of the operator's switch,
and means for holding the brake off from the motor while it is slowing down,
substantially as described.
D
กด 1
T
XV