US728292A - Electric elevator. - Google Patents

Description

No. 728,292. PATENTEDMAY 19, 1903.

F. B. RAB.

ELECTRIC ELEVATOR.

APPLICATION FILED NOV. 16, 1895.

I0 IODEL.

I luna /2'52 W19.

UNITED STATES Patented May 19, 1903.

PATENT OFFICE.-

FRANK B. RAE, OF CHICAGO, ILLINOIS, ASSIGNOR TO JNO. A. ROCHE, OF

CHICAGO, ILLINOIS.

ELECTRIC ELEVATOR.

SPECIFICATION formingpart of Letters Patent No. 728,292, dated May 19, 1903.

Application filed November 16, 1895. Serial No. 569,219. (No model.)

To all whom it may concern.-

Be it known that I, FRANK B. RAE, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Electric Elevator,of which the following is a specification.

This invention relates to electric elevators.

The object of the invention is to provide a novel and useful arrangement for electrically operating elevators.

The invention consists, substantially,in the construction, combination, location, and relative arrangement of parts, all as will be more fully hereinafter set forth, as shown in the accompanying drawings, and finally pointed out in the appended claims.

In the accompanying drawings, Figure 1 is a view showing a general arrangement of apparatus embodying my invention. Fig. 2 is a diagrammatic detail view illustrating the controlling principle of operation of a portion of my invention.

In the drawings reference-sign A designates the car; 8, the hoisting-motor therefor; O, the winding-drum arranged to be actuated by the motor 13 and adapted to receive the hoistingcable D.

F is the controlling device carried by the car and adapted to control the various circuitshereinafter to be referred to. In the particular form shown, to which, however, I do not desire to be limited or restricted, the circuit-controlling device comprises a lever pivoted, as at G, in any suitable or convenient position to be readily grasped and operated by the elevator attendant.

In the particular form of apparatus shown, to which, however, I do not desire to be limited or restricted, the drum 0 is driven from the motor-shaft by any suitable form of gearing, as worm II and gear J.

Electric motors heretofore employed and designed for use, as the hoisting-motor for elevators, have been calculated and constructed in many instances with the maximum load and maximum speed as the basis of calculation. In this construction and arrangement the starting effort or starting torque is obtained from a fixed field magnetization and an increased armature magnetization, the latter created by a large initial [low of current through the armature-circuit, in' which circuit and through which said large initial armature-starting current. is arranged to flow was arranged resistance-coils adapted to be successively cut out as the speed of the armature increased to give the motor the necessary acceleration. This type of motor cannot be applied economically for service in hoisting passenger or other elevators, for the reason that the service requirements of an elevatorhoisting motor are constantly changing, due

to a constantchange in the load imposed upon the motor and the constant starting and stopping. Moreover, as the startingtorqueis produced, as above explained, by a number of fixed turns on the armature and a large current a large part of the available voltage of such current is lost through the resistancecoils made necessary from the time the cur- 7o rent is applied until the resistance-coils are finally cut out. The loss of available vol- "tage through this channel becomes seriously appreciable when it is considered that the motor is required to be constantly stopping and starting when in elevator service. The objections noted are avoided by providing the motor with a large magnetic field and placing thereon ashunt-winding of very many turns,requiringbutasmallcurrent,andwhich in itself is capable of producing the necessary magnetization to run the motor at its maximum speed under its maximum load. In addition to this shunt-Winding I also wind upon the field-magnets a desirable number of coils in series of larger wire, sufficient when all are in live circuit to produce the required number of lines of force necessary to start the armature from its position of rest under maximum load with a current of' reasonably and comparatively small predetermined value. I then successively and automatically cut out sections or coils of this series winding to produce the desired acceleration of speed of the armature, until finally when 5 all of the sections or coils are cut out the motor Operates at full speed under the influence of the magnetism of the shunt-winding, which, as above explained, is suflicient to continue the motor at full speed under maxi- 10o mum load. From the foregoing it will be seen that the speed of the motor is always proportional to the number of series coils that are active.

Reference-signs a and Z) designate the main positive and negative supply-conductors. A connection 0 leads from the positive feedconductor to the control device or lever on the car. This lever may be of ordinary type of lever, to which is pivoted an arm 3, suitably insulated therefrom and of conducting material. Pivotally connected to lever F by means of a pivoted handpiece 4 is a bar 5, arranged to be moved endwise when said handpiece is moved toward the lever, and one endof said bar 5 is pivotally connected to arm 3. A suitable spring 6 serves to normally maintain hand piece 4 in open or separated relation with respect to said lever F. The connection 0 leads to a contact point or brush 7 upon the lever, adapted to contact with arm 3 when the handpiece 4 is grasped and rocked to close the same upon lever F. The opposite end of the control-lever is arranged to engage a pivoted bracket 8 and rock the same. Carried by bracket 8 are the brushes or contact-strips 9 14, respectively arranged to be brought into electrical connection with the contact-points 1O 11 and 12 13, according to the direction in which the lever F, and hence also the bracket 8, is rocked. The pivoted arm 3 is in electrical connection with contact-brush 9. Contacts 10 and 13 are included in the same circuitwith each other, and contacts 11 and 12 are each included in a circuit 61 e.

The arrangement above described constitutes an electrical control device upon the car in place of the ordinary hand device or mechanical control adapted to be operated by the car conductor to operate the switches to turn on or reverse the direction of the current through the motor.

I will now describe a form of switch for turning on or reversing the direction of the motor-current.

Reference-signK designates a suitable form of polarized magnet. Preferably, though not necessarily, this magnet may be constructed on the principle of a dynamo-machine with a single-coil Siemens H-armature L, and the field-magnet R of this armature L may he included in circuit connection f, leading from contact-brush 14 on the car, and is therefore energized in a constant direction. The circuit f, leading to contact brush or strip 14, is made or broken by the control lever or device on the car.

Armature L of polarized switch K carries an arm 15, upon which are mounted the contact-strips 16 17 in electrical connection, respectively, through connections 9 and h with the brushes of the motor The contactstrips 16 17are arranged to make contact, respectively, with the points 18 19 or 19 20, according to the direction in which said armature L is rocked. The arm 15 also carries a brush 21, arranged to make contact with point 19 except when said arm is in its neutral or central positionthat is, when the magnet-field circuitfis broken. By actuating the magnetic-switch-controlling armature L in one direction or the other the brushes or strips 16 17 are moved into position to make or break the circuit through the working motor-armature or to reverse the direction of current through said circuit, thereby reversing the direction of rotation of the motorarmature. At the same time the motor-field is energized in a constant direction through shunt-circuit 1, leading from contact-brush 21 through the motor-field, thence to the negative supply-wire b. It is through this shunt-circuit of the motor-field that sufficient magnetization is induced in said field to maintain the armature of the motor at a maximum speed under maximum load after that maximum speed has been once obtained, as will presently more clearly and fully appear. The arm 15 may be normally held or returned to its central position by means of the spring 29.

The operation of the apparatus so far described will now be set forth, supposing the I parts to be in their neutral position, as shown in the drawings. Suppose the operator to grasp lever B and handpiece 4, closing said handpiece upon the lever. Circuit is immediately made between point 7 and strip 9. If the lever F is then rocked toward the left from the position shown, the contact-strips9 and 14: will be respectively brought into contact with points 10 and 12, thereby completing the circuit from strip 9 through connection 0, through the magnetic-switch armature L,connection n, point 12, brush 14:,and connectionf, through the coils of magnetic-switch field R, thence through the coils of brake-magnet M and connectionsf to the negative line-wire Z). The energizing of this field causes the armature L to rock, say, toward the left, thereby carrying strips 16 17 into contact,respectively, with points 18 19 and also carrying brush 21 into contact with point 19. This point is included in the main motor-circuit z from positive conductor a. Therefore the circuit through the motor-armature and also through the motor-field is made when brushes 16 and 17 contact with point 19, thereby effecting an actuation of the motor in one direction. In the same manner and under the same conditions a rocking of the lever F on the car in the opposite directionthat is, toward the right from its central position-the current through the magnetic-switch armature is reversed, while that through the field-magnet remains the same. This causes the armature to rock in the opposite direction, thereby reversing the direction of current through the motor-armature, while that through the motor-field remains the same, thus reversing the direction of rotation of the motor-armature. Thus it will be seen that the switch-motor K is, in effect, a relay arranged to be actuated by a comparatively small current and the actuation of which cuts in or out or reverses the direction of the motor-current.

It is important that the motor be provided with a brake in order that it may be rapidly brought to rest when the current is cut off therefrom. Itis also desirable that this brake be so arranged that it will become operative immediately upon the breaking of the motor field and armature circuits. I have devised such a brake and arrange the same to be electrically operated from the car. In the particular embodiment ofmy invention,to which, however, I do not desire to be limited, P designates a brake-wheel mounted on the mo tor-shaft and adapted to be engaged by a brake-shoe carried by a pivoted lever N. This lever may be suitably weighted to normally engage said brake-wheel P and arrest the rotation thereof. I form said lever of suitable magnetic material and arrange the same to be acted upon as the armature of an electric magnet M. I include said magnet in the circuitfwith the field R of the magnetic switch K. When, therefore, the circuit is made through this field, and hence when the motor is in operation in one direction or the other, the electromagnet M is energized and the brake-wheel P is relieved of the brakeshoe.

Reference has been made to coils of large wire wound in series upon the motor-field magnets, the purpose of which when all of said coils are in action is to produce or induce in the magnetic field of the .motor the required number of lines of force necessary to start the armature from a position of rest under maximum load with an energizing-current of comparatively and reasonably small predetermined value and that when the motor is started from its position of rest said coils are successively cut out to produce the required acceleration of speed of the arma ture. I will now describe an arrangement whereby this result is accomplished, though it is obvious that the principle involved may be embodied in a wide variety of specific forms of apparatus.

In the embodiment shown reference-signs p p p p, &c., designate the leads to the series coils above mentioned of the motor-field. Each lead is so electrically connected up that said coils may be successively and automatically cut out. I have shown as merely illustrative of the principle involved one form of apparatus for accomplishing the desired result, wherein each lead 19 is connected to a pair of juxtaposited contacts 1* r 'r r, 4%., the members of each pair being respectively arranged on opposite sides of a central position of an arm or cut-out lever 22. Therefore when said arm is rocked either in one direction or the other from its central position the series coils of the motor-field are successively cut out of live circuit, the central position of said arm 22 making contact with the last of the series coils. The circuit for the series coils is made asfollows: from the positive supply conductor a through connection 2 to point 19, thence through brushes 16 or 17,

through connections g or h, the motor-armature, and to point 18 or 20, thence through connection t to the lead-wire of the first of the motor field auxiliary series coils, thence through all of said coils to arm 22 when said arm occupies the position shown in the drawings, thence out through connection y to the negative main conductorb. When arm 22 is moved in either direction from its central position, the auxiliary series coils of the motorfield are successively cut out. The lever 22 may be moved in any suitable or desirable manner, either mechanically or electrically, and controlled either by hand or automatically. In the particular form shown, to which, however, I do not desire to limit myself, I arrange said arm to be moved mechanically and automatically by mounting the same upon a gear 23, arranged to mesh with a worm 24:, mounted upon a shaft 25. When this shaft is rotated in one direction or the other, the arm 22 is correspondingly moved to successively cut out the series coils referred to.

I will now describe an arrangement of apparatus for effecting a rotation of shaft 25, which is intended to be merely illustrative of the principles involved and to which I do not desire to be limited or restricted, and wherein E designates a small pilot-motor, to the arma ture-shaft of which I couple shaft 25 throughthe medium of a magnetic clutch W, which I preferably arrange in the same circuitfwith field R of the switch-magnet and the electromagnet M of the brake above described. When, therefore, this circuit is opened or closed, the shaft 25 is coupled to or uncoupled from the armature-shaft of the pilot-motor E. Mounted upon the car and in electrical connection with the feed connection 0 through lever F are resistance-coils A, connected up in series and adapted to be cut out of said circuit when said lever is thrown in one direction and to be cut into circuit when said lever is thrown in the opposite direction.

B designates an electromagnet spool sleeved upon a magnetic pivoted bar 26, arranged to vibrate between the poles of a magnet 27. The coils of magnet B are in circuit through connection a with the last of the series ofresistance-coils A upon the car and also through connection b with the first of a series of resistance-coils O' ,arranged in series, and to be cut in or out of circuit by any suitable means, as arm 28, which is in circuit through connection 0 with feed connection 0.

From the foregoing it will be seen that when current flows through the coils B in one direction the bar 26 is given a polarity of one sign, and when flowing in the opposite direction said arm is given a polarity of the opposite sign, thereby being repelled or attracted by the respective poles of magnet 27, and hence effecting a rocking of said bar. A spring 30 may be employed to normally maintain said bar in its central position. The

movement of bar 26 effects a control of the pilot-motor armature-circuit in the following lUU IIO

manner: Carried by bar 25 are the brushes 31 32, respectively, adapted to be broughtinto contact with the contact- points 33, 34, and 35, according to the direction in which said bar 26 is rocked. Contacts 33 and 34 are in circuit through connection 01 with the positive supply-conductor a, and contact 35 is in circuit through connection e with the negative supply-conductor Z). The brushes 31 and 32 are respectively connected to the armaturebrushes of the pilot-motor E through connection f g. If desired, I may include in the pilot-motor armature-circuit an electromagnetic brake D, similar to the main motorbrake above described, and arranged and adapted to effect a braking of the pilot-motor armature-shaft when current through the pilot-motor armature-circuit is cut The pilot-motor fields E F are included in circuit through connections 77/ m with connections a and b, respectively, and with the negative supply-conductor I) through connections n.

The shaft may be returned to its normal position when uncoupled from the pilotmotor armature-shaft in any suitable manner, as by means of weighted cords 36, wound upon drums mounted on said shaft.

Of course it will be understood that any other suitable form of switch may be employed for controlling the pilot-motor armature-circuit.

From the foregoing description it will be seen that when bar 26 is moved to the left, for instance, circuit is made from the supplyconductor a through connection 01, contact 33, brush 31, connection f, electro brakemagnet D, the pilot-motor armature, through connection g, brush 32, contact to the negative supply-conductor, and when said bar is moved to the right the direction of current is reversed, thereby reversing the direction of rotation of the pilot-motor armature. \rVhen no current is flowing through electromagnet B, the bar 26 is held in its central position, and hence the current through the motorarmature is broken.

I will now describe the principle upon which the pilot-motorswitch-magnet operates,reference being had to the diagram of Fig. 2. In the arrangement of circuits known as the Wheatstone bridge the principle is well understood that if the four arms of the bridge are of equal resistance or if two of its sides or arms are proportional to the other two sides there will be no difference of potential between the poles to which the galvanometer is usually connected; but if this balance is disturbed upon any one of the arms, either by increasing or decreasing the resistance in said arm, a difference of potential will exist at the terminals of the galvanometer-circuit and current will flow through the galvanometercircuit in a direction dependent upon whether the disturbance in the bridge-arm is due to increasing or decreasing its resistance. For

instance, if in Fig. 2 A 0 E and F repre sent the four arms or branches of a Wheatstone bridge and B the galvanometerand said arms balance-that is, when F is to E as O is to A with reference to their respective resistancesno current flows through the circuit of galvanometerB If, however, the resistance is altered in any of the branches or arms so as to alter the above proportion, current will flow through the galvanometer-circuit in a direction dependent upon whether the resistance is increased or decreased. I make use of this principle in my arrangement and in the practical operation thereof in the form illustrated, the resistance-coils A upon the car and the resistance-coils O constituting the corresponding branches or arms of the bridge. The other two arms may be arranged in any suitable manner. For instance, the pilot-motor field-magnet coils E F may be utilized for the purpose and the pilot-motor switch-magnet B may be employed in the circuit corresponding to the galvanometer-circuit of the Wheatstone bridge. When, therefore, the resistances A on the car are in balance with the resistances O, the resistances E F being the same, no current flows through magnet B. This in practice is the condition when lever F on the car occupies its central position, as shown in the drawings. When, however, the balance is disturbedas, for instance, when lever F is moved in one direction or the other to cut in or out the coils A the static relation between the resistances A and O is disturbed and current flows through the circuit of magnet B in one direction or the other, according to whether the lever F cuts in or out the coils of resistance A, thereby effecting a rocking of the bar 26 and a consequent switching into action of the pilotmotor. It will be seen. that a very small current through the coil B is sufficient for this purpose, and hence said magnet constitutes, in effect, a polarized relay which controls the movement of the pilot-motor, causing it to start and to revolve in either direction according to the position of the lever F on the car. Now if an arrangement is provided whereby the coils of resistance 0 are cut in or out to again correspond with the coils of resistance A a static relation is again established in the Wheatstone bridge and current through the polarized relay B ceases, and the springs 30, returning the bar 26 thereof to its normal position, the pilot-motor circuit is broken and said motor stops. This result may be accomplished in a variety of waysas, for instance, by mounting arm 28 upon a gear 37, arranged to mesh with worm 33 upon shaft 25. This is merely illustrative of an operative form of apparatus for accomplishing the desired result, and I do not confine or limit myself thereto.

In the practical operation of an electric elevator it is important that provision be made for automatically stopping the hoisting-motor at the extreme limits of travel of the elevator as a safety appliance to prevent injury in case of neglect or inattention on the part of ture and field.

the elevator-conductor. I accomplish this result in a most efiicient manner by including in the connection 61 e switch-levers 40 41, respectively arranged at the top and bottom of the elevator-well and in position to be engaged by the car when it arrives adjacent to the top and bottom limits of travel and opened. Suitable springs may be employed to hold said switches in normally closed position. The operation of this feature is as follows: Suppose the lever F to be thrown to the right from the position shown in the drawings and the car to be ascending. The circuit for switch K will be through brush 9, point 10, connections 0 and it, through switchlever 40 and connection 6 to point 12, through brush 14, connection f, field R, magnet M, clutch IV, to supply-cond uctor 1). Now when the car attains its limit of movement it breaks this circuit, thereby cutting out field R, ap plying brake M, releasing clutch W, and permitting main switch-arm 15 to be moved under the influence of its springs 29 to position to break the circuits through the motor arma- The switch-lever 41 at the bottom of the well, however, is in closed position, thereby permitting circuit to be made Iherethrough when the lever on the car is thrown in the opposite direction to reverse the motor, and hence permitting the carto descend until said switch-lever 41 is opened by the car engaging the same at the opposite limit of its travel.

From the foregoing description it will be seen that when the operator removes his hand from the control-lever the handpiece 4 opens under the influence of spring 6, thereby completely cutting off the current from the hoisting-motor switch, returning the main switch to its normal position, setting the motorbrake, and releasing clutch W. The release of clutch W causes shaft 25 to return to its normal position, thereby returning the starting-arm 22 and also the bridge-arm 28 to their normal positions. The return of leverF toits central position again establishes equilibrium of resistance in the coils A and 0, thereby cutting out pilot-motor E and setting the pis lot-motor brake D. It will also be seen that a movement of the lever F in one direction causes the car to travel in one direction and a movement of said lever in the opposite direction causes the car to travel in the opposite direction. It will also be seen that the speed of the elevator in either direction is proportioned to the distance through which the operator moves. the lever, forthe reason that that position controls the position to which the arm 28 is moved by the pilot-motor, and hence also the position to which switch-arm 22 is moved.

The operation of the apparatus will be readily and fully understood from the foregoing description, taken in connection with the accompanying drawings. I

The principles underlying my invention and as above explained may be embodied in p many different forms of operative apparatus and still fall within the spirit and scope of my invention. I desire it to be distinctly understood, therefore, that I do not limit or restrict myself to any particular form or embodiment; but,

Having explained the object and nature of my invention and a form of apparatus embodying the same and having specifically described the arrangement, function, and mode of operation of said apparatus, what I'claim as new and of my own invention, and desire to secure by Letters Patent of the United States, is

1. In an electric elevator, a hoisting-motor, having the usual armature and field coils, an auxiliary. field-coil, and a pilot-motor arranged to cut out said auxiliary field-coil; as

and for the purpose set forth.

auxilary field-coil, a pilot-motorarranged to cut out said auxiliary field-coil, and means for controlling said pilot-motor from the car; as and for the purpose set forth.

3. In an electric elevator, a hoisting-motor, having the usual armature and field coils, auxiliary field coils arranged in series, a switch arranged to successively cut out said auxiliary coils, and a pilot-motor for actuating said switch; as and for the purpose set forth.

4C. In an electric elevator, a hoisting-motor, having the usual armature and field coils, auxiliary field coils arranged in series, a switch arranged to successively out out said auxiliary coils, a pilot-motor for actuating said switch, and means for controlling said pilot-motor from the car; as and for the purpose set forth.

5. In an electric elevator, a hoisting-motor, having the usual armature and field coils, circuits therefor, auxiliary field-coils, a circuit therefor, a switch arranged to control said circuits, a polarized magnet arranged to control said switch, and a circuit therefor, and means for controliing said circuit from the car; as and for the purpose set forth.

(3. In an electric elevator, a hoisting-motor, having the usual-armature and field coils, circuits therefor, a switch arranged to control said circuits, means for controlling said switch from the car, an electrically-operated brake for said motor, an independent circuit therefor, and means for controlling said independent brake-circuit from the car; as and for the purpose set forth. v

7. In an electric elevator, a hoisting-motor, having the usual armature and field coils, circuits therefor, an electrically-operated switch arranged to control said circuits, a circuitfor said switch, said circuit controllable from the car,'and an electrically-operated brake for said motor, arranged in said switch-circuit; as and for the purpose set forth. 7

8. In an electric elevator, a motor, motorcircuits, an electrically-operated switch arranged to control the same, and means for controlling said switch, comprising the following elements, a pair of fixed resistances, and a pair of "ariable resistances, said fixed resistances in circuit with each other and respectively in circuit with the members of the pair of variable. resistances, said switch being arranged in circuit with said several resistances, and means for varying the resistance in one of i said variable resistances; as and for the purpose set forth.

9. A pilot-motor for electric elevators, circuits therefor, a magnetic switch arranged to control said circuits, a pair of variable resistances', a pair of fixed resistances, said switch being included in circuit with said resistances, and means whereby the resistance in one of said resistances maybe varied; as and for the purpose set forth. 7

10. A motor, circuits therefor, a magnetic switch for controlling said circuits, a pair of sets of variable-resistance coils, a pair of fixed resistances, said switch included in the circuit with said resistances, and means for varying the resistance in one of said sets, whereby said switch isjactuated and the motor started; as and forf the purpose set forth.

11. A motor, circuits therefor, a magnetic switch arranged to control said circuits, sets of variable resistances, sets of fixed resistances, said switch included in circuit with said sets of resistances, means for varying the resistances'in one if said sets of variable resistances, whereby said switch is actuated and said motor started, and means for varying the resistance in the other set of variable resistances, whereby said switch is rendered inoperative, thereby breaking said motor-circuits; as and for the purpose set forth.

12. A motor,circuits therefor, a magnetic switch arranged to control said circuits, sets of variable resistances, sets of fixed resistances, said switch included in circuit with said several resistances, means for varying the resistance in one of said sets of variable resistances, whereby said switch is operated and said motor-circuits are made, and means for automatically varying the resistance in the other set of variable resistances, to correspond to the resistance in its cooperating set of variable resistances, whereby saidswitch is rendered inoperative and said motor-circuits are broken; as and for the purpose set forth.

13. A motor, circuits therefor, a magnetic switch arranged to control said circuits, sets of Variable resistances, said switch arranged in circuit with said several resistances, means for varying the resistance in one of said sets of variable resistances, and means, actuated by said motor, for correspondingly varying the resistance in the other'set of variable resistances, whereby said motor-circuits are made and broken; as and for the purpose set forth. I

14. In an eiectric elevator, a car, a motor, circuits for said motor, a magnetic switch for controlling said circuits, sets of variable resistances, in static relation to each other, one of said sets carried by the car, sets of fixed resistances, said switch included in circuit with said resistances, means for varying the resistances on the car, whereby said static relation is disturbed, and means for correspondingly varying the resistance in the other set of variable resistances, whereby said static relation is again established; thereby actuating said switch to make and break said motorcircuits; as and for the purpose set forth.

15. In an electric elevator, the combination with a car, ofa hoisting-motor, circuits therefor, an electric switch for controlling said circuits, a circuit for said switch, means carried by the car for establishing current in said switch, circuit whereby said switch is actuated to make said motor-circuits, and automatic means for arresting current through said switch-circuit, whereby said switch is prevented from breaking said motor-circuits; as and for the purpose set forth.

16. In an electric elevator, the combination with a car and a hoisting-motor, of a pilotmotor, a shaft actuated thereby, a switch for controlling the circuits of said pilot-motor, means carried by the car for actuating said switch to complete the pilot-motor circuit, and means actuated by said shaft for operating said switch to break said circuit, as and for the purpose set forth.

17. 'In an electric elevator, a main hoist-ingmotor having the usual armature and field coils, auxiliary fieldcoils, a pilotmotor, means for controlling the action of said pilotmotor, a shaft actuated by said pilot-motor, a switch actuated by said shaft, arranged to cut said auxiiiary field-coils out of circuit; as and for the purpose set forth.

18. In an electric elevator, a main hoistingmotor, having the usual armature and field coils, and having auxiliary fieldcoils arranged in series, a pilot-motor, means for controlling the same, a shaft actuated thereby, a switch actuated bysaid shaft, adapted to successively cut out said auxiliary field-coils of the main motor; as and for the purpose set forth.

In witness whereof I have hereunto set my hand this 9th day of November, 1895.

FRANK B. RAE.

Attest: V

M. I. OAVANAGH, S. E. DARBY.

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