US2019917A - Elevator leveling control - Google Patents

Description

Nqv. 5, 1935. v A. J. LIEBENBERG 2,019,917

ELEVATOR LEVELI'N G CONTROL Filed Sept. 14, 1933 s Sheets-Sheet 1 arrow ormnuq DEVIL:

INVENTOR Mvl yv ATTORNEYS Nov. '5, 1935. A. J. LIEBENBERG 2,019,917

ELEVATOR LEVELING CONTROL 7 Filed Sept. 14, 1933 3 Sheets-Sheet 3 BY ATTORNEYS Patented Nov. 5, 1935 UNITED STATES PATENT OFFICE ELEVATOR LEVELING CONTROL Arthur J. Liebenberg,

Cincinnati, Ohio, assignor Application September 14, 1933, Serial No. 689,441

6 Claims.

This invention relates to leveling control for electrically operated elevators.

The invention contemplates the use of a pair of pliotron units, each unit energized by a stationary vane placed in the elevator hatchway in relation to a landing or floor level, as primary means of preferred type for automatically controlling the starting of the elevator motor for a slight movement or travel of the elevator in an appropriate direction after the general control has functioned to bring the elevator to a floor stop and failed in bringing the elevator floor in level with the landing. The pliotron units preferably are mounted upon and move with the elevator, one for up leveling motor starting control and the second for down leveling motor starting control, each unit cooperating with a respective vane, one for each floor or landing for a definite starting direction control governed at which side of the landing the floor of the elevator is out of level, asabove or below, and for the control 01' an electro-mechanically operated switch actuated by a frictional coupling with the elevator motor shaft in its leveling starting motion or rotation for cut-out or stopping control of the motor. The leveling system or controlling devices can be incorporated with various types of electric elevator control systems, either attendant car switch operated or push button automatic, with the leveling control automatic after the general controlling mechanism has been operated to bring the elevator to a stop, and the car stopping with the elevator floor out of line with the floor landing.

An object of the invention is to provide a system of leveling control for electrically operated elevators, which is entirely automatic and effective only after the elevator has been brought to a stop by the general controlling devices, and when the floor oi the elevator, when stopped, is out of line with the landing.

Another object of the invention is to provide an automatic elevator floor leveling control easily installed and operated in connection with the various types of elevator controlling systems, one of simple and cheap construction and in which extremely accurate stops are secured with lower ratio alternating current motors with less control apparatus.

Various other features and advantages of the invention willbe more fully set forth in the description of the accompanying drawings, in which:

Figure 1 is a diagram of the leveling control circuits.

Figure 2 is a diagrammatic front view of the motor cut-cut switch for cutting out motor circuit after leveling.

Figure 3 is a diagrammatic side elevation of the same.

Figure 4 is a diagram of the pliotron circuit.

Figure 5 is a front elevation of the motor leveling cut-out switch with, the casing broken away to more completely disclose the mechanism, and illustrating a modified form of construction from that illustrated in Figure 2.

Figure 6 is'a side elevation projected from Figure 5 with parts broken away to illustrate the manner in which the switch carrying plates are journalled.

Figure 7 is a top plan view of the same.

Figure 8 is a view of the device in operation. the magnet having been energized, causing the movable plate to swing and contact with the stop on the stationary plate.

The elevator car or cab is equipped with or has installed thereon two pliotron units, one for up direction leveling control and a second for down direction control. A pair of stationary vanes for each floor or landing, the vanes of each pair for a landing are suitably spaced apart and relatively offset for respectively cooperating with the pliotron units, and positioned in the hatchway, one slightly above and the other slightly below the landing level, causing the unit, when opposlngly spaced elements of a unit come within intimate relation with the vane, to become energized for a predetermined control of the elevator motor controlling mechanism.

In the present instance the pliotron units control a low speed and direction switch corresponding to the direction in which the car must travel for floor or landing leveling. Each pliotron unit therefore automatically controls the motor controlling switch devices for a motor starting in one direction, the starting direction depending on which side of the floor landing level the car has overrun, whereby the elevator motor is started in the appropriate direction for moving the car from its overrun position to the floor level.

The pliotron units are of duplicate construction and constitute a commercial product in which a pair of air core coils are influenced by a plate passed therebetween. The air core coils are respectively mounted within a pair of spaced parallel non-metallic arms extended from the elevator for passing therebetween, a stationary metallic vane mounted in the hatchway in relation to a landing or station for which the leveling is M governed.

In Figure 4, l indicates a three electrode tube designed for relay work for use with a standard four pin socket suitably mounted with the filament of the tube in a vertical position, and the tube under shock absorbing suspension so that it is not injured by vibration or shock. The tube has a cathode 2 connected to the terminals B and A+ of the unit and the terminal A+ is connected by a conductor 3 to a 3- terminal of the second or down level control pliotron unit, connecting the cathodes of the tubes of the two units in series.

The grid 4 of the tube connects with a condenser 5 by a conductor 6 and the condenser 5 connects with a second condenser I by a conductor 8. A resistance 9 is placed in shunt with the condenser 5. The condensers 5 and 1 connect with a fine wire coil I'll of the transformer by a conductor II and the coil also connects with the terminal A+ by a conductor I2 with the condenser I placed in shunt with the coil Ill. The opposite or second coil I3 01 the transformer and of coarse wire, connects with the plate ll of the tube by a conductor l5 and with the terminal D+ by a conductor IS.

A third condenser I1 is placed in shunt with the terminals D+ and A+ by conductors l9 and 20.

For the purpose of exemplifying the leveling control and the mechanism employed, it will be assumed that the elevator controlling devices either as a manually actuated switch or automatic push button have been operated for bringing the car to a stop at a floor landing, and that the car has moved either short of the landing level or has overrun the same within a leveling zone to render either of a pair of pliotron units efi'ective to become energized for operating a relay which in turn controls a circuit for operating a motor controlling switch as the main direction or starting switch.

As diagramed in Figure 1, various control devices for motor, low speed, high speed, interlocking, elevator, brake, etc., havebeen eliminated for the purpose of simplifying the disclosure.

It may also be assumed that the elevator has stopped short of the landing level and the pliotron unit for the motor up-starting control energized due to its relation with a stationary vane in the elevator hatchway as projected between the spaced coils Ill, l3 oi the up pliotron unit. The terminals B- for the cathode of the tube of the up pliotron unit connects with the electric source of supply of power feed line by a conductor 2|. The electric source for elevator service is usually from a generator of a motor generator unit when the main electric power for the elevator motor is an alternating current, although the electric current supply for the control devices may be from any other available source.

The conductor 2i may include or have interposed therein a switch 22 either manually or electrically operated for controlling the circuit to the pliotron units, the switch preferably being located in the elevator cab or car for cutting out the automatic leveling control for operation of the car in the general manner.

The pliotron units connect in series respectively with the circuits that connect with the elevator motor main direction switches and are only eiTective for motor starting in an appropriate direction after the elevator has either overrun or is short of its landing. The up pliotron unit connects in series with the feed line or circuit that connects with the elevator motor main direction switches and when energized controls the circuit to the motor up direction switch as one of the main direction switches on the elevator motor controlling apparatus.

A conductor 23 connects with the D+ terminal of the up pliotron unit and with a magnet coil or a switch device or relay designated U--24, the relay 0: switch device having one set of normally open contacts which are closed when the magnet coil of the switch U-24 is energized for a circuit control to the main up direction switch of the motor and in particular for a control of the circuit to the magnet coil of the motor up direction switch designated as Ul.

The pliotron units, preferably, may be referred to as electric discharge devices, each provided with a pair of electric coils ill and i3 in the input or grid and out-put or plate circuits respectively, which coils are so mounted as to be in mutual inductive relation with each other although spaced apart somewhat and thereby maintain the discharge devices in an oscillating condition. Under these conditions the coils for the relays U--24 and D-2l are in efiect deenergized, the direction current through the coils being of a low value as compared to the current ,required to operate them. The vanes which are cally isolate the two coils of each pair when it comes therebetween, and consequently the oscillating condition in the discharge device is terminated. Under these conditions a direction current flows in the out-put circuit of the particular discharge device and energizes the selected relay coil U-24 or D-21, as the case may be.

A conductor 26 connects in branch with the magnet coil of the up leveling switch U-24 and also with the magnet coil of a similar switch or relay D-21 for down leveling control, the latter controlled by the second or down pliotron unit. The conductor 25 connects with a magnet coil of a relay 28 and in branch with one of the set of contacts of a relay 29. The relay 29 is a magnetic time relay having two sets of contacts. One set of contacts is connected in series with the feed line to low speed resistance cut-out magnets 01' a pair of relays, as a part of the motor speed control, subsidiary, however, to the direction control of the present system for leveling, while the second set of contacts connect in series with the feed line to the magnet coil of a relay 28 and as shown in the diagram, one of the contacts connects with a conductor 3!! to the feed line 3|.

In the circuit or conductor 26, a set of normally closed contacts of a magnetictime relay 32 are interposed. The coilof therelay 32 is energized through normally open contacts of a relay which has its magnet coil in series with the car switch circuit, also subsidiary to the present system.

The time relay 32 is employed to give the elevator opportunity to stablize before either of the leveling relays U-24 and D2l come into play. The relay D2'I has its magnet coil in circuit connection with the down pliotron unit which is substantially of a construction as heretofore described for the up pliotron unit. The magnet coil of the relay D2l is connected by a conductor 33 with the D+ terminal of the down pliotron unit and with the conductor 26 which is common to the coils of both leveling relays U2l and D2l. The timing is minute; merely sufficient to permit the various devices to follow a sequence more or less necessary for eflicient control.

As for example, relay 32 is timed or rather is retarded in its operation so that its contacts are not quickly closed, to allow the motor reversing, either direction switch Ul or D-2, to normalize after a car switch control, before either again is influenced for a motor starting leveling control by either of the leveling relays U24 or D 25, allowing the car to stop before it is again started in the appropriate direction for leveling.

The relay 28 has one set of normally closed and one set of normally open contacts. The normally closed contacts connect in series with a common feed line to the car switch, and not particularly concerned with the leveling control. The normally open contacts connect in series with a feed line 34 through a conductor 35 and with a magnet coil of an electro-mechanically operated or brake switch device at the end of the elevator motor shaft and thence to the feed line 3|. The coil of the relay 28 connects in series with the contacts of the relays U24 and D--21 and acts as an interlock to the car switch circuit when the car is leveling so that as long as the relay 2!! is energized, the movement of the car switch is inefiective.

Also, when the relay 29 is energized, it causes the magnet coil 36 of the brake switch to be energized resulting in a set of normally closed contacts of said brake switch device to be broken with the rotation of the motor, thereby breaking the circuit to the magnet coil of the relay 29. The coil of the magnetic time relay 31 connects with the feed line 3| by a conductor 38 having a resistance 40 interposed therein and by a conductor 4| with the conductor 35 to a contact of the normally open contacts of the relay 28.

The coil of the relay 28 connects in series with the contacts of the relays U-24 and D-21 serving for both up and down leveling control, by conductors 42 and 43. Each of the relays U-24 and D21 has one set of normally open !contacts. The contacts for the relay U 24 when closed connect in series with the coil of the elevator motor up direction switch UI by a conductor 44 and the contacts for the relay D21 with the motor down direction switch D-2 by a conductor 46.

The coils of both main direction switches U-land D-2 are connected by a conductor 41 with the feed line 34. Contacts of various other control relays may be interposed in the circuit connecting the contacts of the relays U24 and 13-21 with the motor direction switches Ul and D2 as for interlock control to prevent the direction switches from being simultaneously operated.

The pliotron units control the starting of the motor in appropriate direction for leveling after the car has been brought substantially to a stop in either an overrun or short position relative to the landing and an electro-mechanically operated or brake switch on or in connection with the motor shaft controls the stopping of the motor for leveling.

The electro-mechanically operated or brake switch on or in connection with the motor shaft comprises a pair of relatively opposing brake levers 49-49, arranged at opposite sides of a drum or pulley 50 fixed on an end of the shaft 5| of the elevator motor.

The brake levers, each at its upper end, are

pivotally mounted on a swinging plate 52. The brake levers are each provided with a shoe 53 for frictionally contacting with the periphery of the pulley, when the levers are compressed toward each other by the magnet 36. The levers are held in a retracted position to release or free the shoes from the pulley by a spring 54 engaged about a rod 55 connecting the upper ends of the levers 49. The lever supporting plate 52 is pivoted to a stationary bracket or support 55a with the fulcrum axis coaxial with the axis of the motor shaft. Thus, when the brake levers are clamped to the pulley the rotation of the motor shaft in either direction will swing the plate 52 in a direction corresponding to the direction of shaft rotation. The magnet 36 when energized attracts the brake levers compressing the shoes thereof against a pulley frictionally connecting the levers and plate 52 with the motor shaft. The lower end of the plate 52 carries an insulated stud 56 extending laterally from the plate and between a pair of relatively opposing yieldable stationary contacts 5151 which, when both are in connection with the stud, are in circuit connection with the coil of the relay 29 and this circuit is broken with the starting of the motor, swinging the plate 52 through its clutch connection with the motor shaft by the brake levers 49 in frictional or gripping contact with the pulley 50.

The contacts 5151 when contacting or enaged with the stud 56, connect with the feed line 34 by a conductor 58, and by a conductor 59 with the magnet coil of the relay 29, and from the coil of the relay 29 to the feed line 3|, the conductor 59 having a resistance element 60 interposed therein.

The brake switch serves to break the motor circuit or circuit for either of the direction switches, whichever is in service for motor starting, and therefore fimctions only for stopping the motor after it has been started by either of the pliotron units, or other circuit controlling means influenced or actuated by the elevator cab at either a short or over-run position relative to a floor or landing or by the elevator cab when within a leveling zone.

The contacts 5151 are normally closed and only broken after the motor has been started for leveling. Therefore the coil of the relay 29 in the circuit with the contacts 5151 is energized continuously. As the contacts 5151 are broken quickly, it is necessary to use an adjustable relay in series with the magnet coil of the relay 28 which is in series with the contacts of the relay U-24 and D 21 controlling the circuit to the main direction switches U--i and D-2 respectively for otherwise the leveling would be accomplished too slowly. The relay 29, therefore is a time relay adjustable so that the speed of leveling can be increased or decreased.

The contacts of the relay 29 control the cir cuit from the feed line 3| tothe pliotron units and also the circuit from the feed line 3| to the contacts of the relays U-24 and D21 and motor direction switches U! and D'I when the contacts of the relays U--24 and D-21 are closed. There must be a suflicient time allowance to accomplish the full leveling movement of the elevator, and for a continuous and sequencial performance of the leveling devices of the system, and avoid any repeat performance which may result from too quick operation of some of the devices.

Several of the relays which have been designated as time relays are of a type in which the armature thereof is retarded or sluggish in its active movement upon being influenced by its magnet coil to permit other relays to normalize before a control circuit is completed. The structure of suchtypes of relays and their use are common in the art.

The pliotron units are ineffective to exert any influence over the motor during travel of the car under control of the car switch, due to the operation of the interlock relay 32, as its contacts are in the feed circuit to the leveling relays U24 and D2'l, which are open while the main controlling mechanism to the motor is in operation and the feed circuit for the leveling relays does not close until the elevator comes to a stop. As the leveling mechanism is auxiliary to the main motor control mechanism it can be cut out at will and the elevator operated in the general manner.

An operation of the leveling system is as follows: After the elevator has come to a stop or point at which the general controlling mechanism for a landing stop should not bring the elevator to the landing level, say short of the landing, a stationary vane in the hatchway for the landing will extend between the coils I0, l3 oi the up pliotron unit on the elevator energizing relay U24, if the lock-out relay 32 of the motor controlled system is de-energized. The pliotron unit will cause the leveling relay U24 to be energized, closing its contacts and completing the circuit for the main up direction switch Ul of the motor controller, starting the motor in an up direction. The circuit extends from the up pliotron unit by a conductor 22 to the magnet coil of the up leveling relay U-24, through the coil of saidrelay, and by a conductor 26 to a set of contacts of the relay 29, which are closed as the coil of said relay is normally constantly energized, and thence by a conductor 30 to the feed line 3|, Energizing the coil of the relay. U24 also completes a circuit from the feed line 3|, conductor 30, closed contacts of the energized relay 29, thence through the coil of relay 28, and conductors 42, 44, which are connected through the closing of the contacts controlled by relay U-24 to the motor main up direction controlling switch U-I. The relay 28 having its magnet coil in circuit with the direction switch Ul is likewise energized closing its contacts, completing the circuit to the magnet 36 of the brake switch at the end of the motor shaft, compressing the brake levers 49-49, coupling the swinging plate 52 to the motor shaft, the plate thereby moving with the motor shaft breaking the contacts 51-51 and the circuit to the time relay 29 which in turn completes the controlling circuit to the up direction switch U-l.

When the car switch has been thrown to its neutral position for controlling the motor for a car stop at a selected floor, should the car fail to stop at the floor level and be in a position below the level of the floor, relay 32 will be deenergized, being thrown in circuit connection upon placing the car lever to neutral position. The up electron unit will energize the up relay U24, closing the controlling circuit to the up direction switch U-I a controlling circuit for the direction switch Ul being complete from the feed line 3|, conductor 30, contacts of relay 29, conductor 26, through coil of relay 28, conductor 42, to contacts of relay U-24, conductor 44, to the coil of direction switch Ul, and thence by conductor 41 with the feed line 34. A controlling circuit, likewise, will be completed with the magnet coil 36 of the brake switch, connecting with the feed line 3| through conductor 35, and by a conductor 35 through the contacts of relay 28, connecting with the feed line 34 through the conductor 35. The coil of the relay 28 is energized simultaneously with the energization of either coils U-24 or D- 21, being connected in the circuit of the coils of said relay U-24 and D2I by a conductor 26, contacts of relay 32, and by conductor 42 with the contacts of either of said relays U-24 and D-2'|, and the relay coils of the direction switches in U| and D2, and by conductor 41 with the feed line 34, thereby controlling the engagement of the clutch with the motor shaft for operation with the rotation of the shaft to open the motor circuit controlling switch in the running circuit 15 of the motor.

As the leveling motion required is usually slight, say within one inch of the floor landing, only a fraction of a revolution of the motor is necessary. The motor starting at slow speed, 20

will, however, respond sufficiently to function within time allowances made and without a jerk.

On alternating current motors different amounts of starting resistance are necessary for different loadings if smooth starting is de- 25 sired. Also, static friction requires different torques for different loads, and it is necessary to restrain the excess torque needed to overcome static friction as quickly as possible, as soon as the machine starts to move. quire no consideration due to the fact that for leveling, the motor starts at low speed requiring no speed regulation, and the motor circuit is cut out as quickly as possible after motor starting,

the motor moving but a slight fraction of a 35 revolution, as a small distance of car travel is only required for leveling.

The pliotron units are preferably employed as a medium responsive when the car in its traverse, reaches or passes definite points or moves within zones without making any contacting or tripping connection between the relative stationary and moving parts, thereby eliminating wear and breakage of the parts.

It is obvious, however, that mechanical types of circuit control or electric current make and break devices may be employed, trip actuated by the moving car at certain points in its traverse for operating the switch device actuated by the motor for cutting off the motor current, after a starting for leveling through its starting momentum effecting its own stopping control,

Referring to Figures 5 to 8 inclusive, illustrating a modified form of motor operated switch for cutting out motor circuit for car leveling, the construction of switch provides for an increased motor leveling operating interval, or increased arc of motor shaft rotation before circuit to elevator motor is cut off. This facilitates in the installation and in regulation.

In the modification the opposed contacts 51, 51 are mounted as a unit for a slight arc of movement with the movable contact or stud 55. A pair of brake levers 49, 49 are pivotally mounted, each respectively upon a stud 6| fixed to and laterally extending from a swinging plate 52. The brake levers are arranged to clasp about opposite sides of the end of the elevator motor shaft 5|, or pulley fixed thereon, and adapted to be compressed against the periphery of the motor shaft by a magnet 36 mounted upon the rear side of the swinging plate 52 between the opposing ends or arms of the brake levers 49.

The brake levers are neutralized or retracted, each by a spring 62 on one end of a rod 63 lcose- 1 Such factors re- 30 ly extending across the upper ends of the brake levers 49.

The swinging plate 52 is journalled upon a stud bolt 64 mounted upon and engaged through a cross bar 64 rigidly secured upon brackets 65, 65 fixed to the interior of the casingv 66. The lower or depending end of the swinging plate 52 carries a laterally extended stud 56, as a movable contact extending between the movable contacts 51, 51, upon a second swinging plate 61. This second swinging plate 61 is pivoted upon the stud bolt 64 and depends therefrom parallel with the swinging plate 52. The movable contacts 51, each is mounted within a tubular housing 68, fixed to the lower end of the swinging plate 61 and urged outwardly toward and against the stud 56 by a spring 69, enclosed and confined within the housing 68 and bearing against the head end of the contact 51.

A rigid plate 10 is fixed to and depends from the cross bar 64, its lower end provided with a laterally extended stop lug 1|, to be alternately engaged by a pair of lugs 12 projecting from the second swinging plate 61 at relatively opposite sides of the stationary stop lug 1 I. The swinging plate 61 is provided with a plurality of apertures 13 for adjustably locating the lugs 12.

In a neutral position of the parts as shown in Figure the swinging plates 52 and 61 are in a perpendicular position, and the contacts 51, 51 engaged with the contact stud 56. Upon starting the elevator motor in either forward or reverse direction of rotation depending upon the direction required for car fioor leveling, the magnet 36 appropriately with the motor starting is energized actuating the brake levers 49, 49 for clutching to the motor shaft. The swinging plates 52, 61 swing as a unit with the rotation of the motor shaft until the stationary stop lug 1| is engaged by either one of the lugs 12 of the swinging plate 61 arresting the same and the continued movement of the swinging plate 52 compresses on the movable contacts 51 breaking contact with the other movable contact 51, opening a control circuit to the motor for motor stopping.

It is recognized that the system provides for motor leveling control in either forward or reverse directions of motor rotation, to accommodate for elevator either coming short or overrunning a landing, and for some installations the leveling control may be only in one direction as when the elevator only services the floors in one direction, in which instance the control system for leveling need only be equipped for a one direction control.

Having described my invention, I claim:

1. An automatic leveling control for an electric motor driven elevator comprising, a pair of electro-magnetically operated direction motor controlling switches, one for up and the other for down motor direction control, a pair of pliotron units moving with the elevator, one for motor up direction leveling control and the second for motor down direction leveling control, vanes mounted in the elevator hatchway with respect to a floor level, each respectively to cooperate with a pliotron unit, relays respectively controlled by said pliotron units, each in circuit with one of the pliotron units and effective therewith for controlling the circuit to one of said motor direction switches, for a motor starting control when a pliotron unit is in cooperation with a vane, and an electro-magnetically operated switch device responsive with either of said relays for frictionally coupling with the motor shaft when the motor has started in a car floor leveling movement for cutting out the circuit to said motor direction controlling switches to effect the stop of the car when level with the floor.

2. An automatic leveling control for an electric 5 units moving with the elevator, one for motor up direction leveling control and the second for motor down direction leveling control, vanes mounted in the elevator hatchway with respect to a floor level, each respectively to cooperate with a pliotron unit, for respectively controlling said 15 motor controlling switches, for a motor starting control when a pliotron unit is in cooperation with a vane, and an electro-magnetically operated switch device responsive with either of said motor controlling switches for frictionally coupling with the motor shaft when the motor has started in a car leveling movement for cutting out the circuit to said motor direction controlling switches to effect the stop of the car when level with the floor. 3. An automatic leveling control for an electric motor driven elevator comprising, a pair of electro-magnetically operated direction motor controlling switches, one for up and the other for down motor direction control, a pair of pliotron units moving with the elevator, one for motor up direction leveling control and the second for motor down direction leveling control, vanes mounted in the elevator hatchway with respect to a floor level, each respectively for operating a motor direction controlling switch for controlling an operating circuit to one of said motor direction switches for a motor starting control when a pliotron unit is in cooperation with a vane, a

switch in a controlling circuit of said motor di- 4 rection controlling switches, and means for operating the switch including a clutch irictionally coupling to the motor shaft when the motor has started in a car leveling movement for cutting out the control circuit to said motor direction controlling switches to effect the stop of the car when level with the floor.

4. An automatic leveling control for an electric motor driven elevator comprising, a pair of electro-magn'etically operated direction motor controlling switches, one for up and the other for down motor direction control, a pair of pliotron units moving with the elevator, one for motor up direction leveling control and the second for motor down direction leveling control, vanes mounted in the elevator hatchway with respect to a floor level each respectively to cooperate with a pliotron unit controlling the circuit of a pliotron unit, and one of said motor direction switches, for a motor starting when a pliotron unit is in cooperation with the vane, a switch in the running circuit of the motor, and means responsive with the control of either of said motor direction switches for operatively connecting the switch with the motor to cause opening of the 5 switch to effect the stop of the car when level with the floor.

5. In an electric elevator, the combination of a hatchway, a car in said hatchway, an electric motor for driving the car, reversing switches for controlling said motor for forward and reverse operation,leveling means for governing the motion of said motor and leveling the travel of said car, comprising a pair of devices mounted in said hatchway in spaced relation with each other and in relation to a floor Ievei at which the car control is to be effective, a pair of devices mounted on said car arranged each to cooperate respectively with one of said first pair of devices for rendering said reversing switches selectively responsive for motor control and direction of movement of said car, a switch device in the running circuit of the motor, and means for operating said switch responsive with said reversing switches and including a clutch for engaging the motor shaft to cause opening of the switch to efiect the stop of the motor when the car is level with the floor.

6. In a. floor leveling control for electric motor driven elevators for stopping an elevator level with a floor, comprising a switch in the running circuit of the motor and means for operating the switch, including a clutch for engaging the motor shaft and positioned responsive means efiective to control engagement of the clutch in accordance with the position of the car with respect to the floors, to cause opening of the switch to effect the stop of the car when level with the floor.

ARTHUR J. LIEBENBERG.

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