US2597586A - Elevator control system - Google Patents

Description

May 20, 1952 P. c. KEIPER ETAL 2,597,586

ELEVATOR CONTROL SYSTEM Filed Feb 5, 1950 5 Sheets-Sheet l A23A A22 A24 A2l a ADI AUZ AUB A02 GIA-0 A03 AvTuAEI ARI i V A03 ADI Asw TAU5 AEZ AUS AwzA-z Ax A30 Fl g v L+2 gl L-z L+2 Fi .|A.

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ATTORNEY May 20, 1952 P. c. KEIPER ErAi. 2,597,586

ELEVATOR CONTROL SYSTEM Filed Feb. 3, 1950 5 Sheets-Sheet 2 aus es FFZ EE B6 Bis-3 Bis-4 s ,ad mi v AFi AEI A52 so Asw A7c o c6 N0 C|33 C|34 22.36 if *GDL- A07 l B07 l C07 7DR2 6UR2 Aas aus cas 2 5UR2 Bas cas 5DR2 Ca2 C4K zuRz Aaa aaa 2DR2 BK Bal B46 AOI |uR2 I I 6 Fig.5.

INVENToRs Phillip C.Keiper ond Wolter H.Esseimon ATTORNEY May 20, l

Filed Feb. 3, 1950 L+6 Ar7 BIB-7 D cl2-6 Cor A 8X6 ala-llu 0 In o Il WITNESSES:

A13-s "ggyoga Ara AK'ml uns o 0 rl A6 Next Up ANU Stort Up P. C. KEIFER ETA-L ELEVATOR CONTROL SYSTEM CorB BIB-6 ha Lol an B50 rBBG Next Up BNU Stor? Up NextDown BJB SortDown CIZ-7 m# AXS M342 K2 5 Sheets-Sheet 4 U6 6,-, CorC L 6 klnService cl2 NextUp CNU A13-s CK2 StartUp |-3 All-6 b BIB-I2 K6 Ell-6 l (SIL 1 INVENTORSc; Phillip C. Kepr ond WGHerHEsseImcan.

ATTORN EY May 20, 1952 P. c. KEIPER :TAL

ELEVATOR CONTROL SYSTEM 5 Sheets-Sheet 5 Filed Feb. 3, 1950 Patented May 20, 1952 UNITED STATES PATENT OFFICE ELEVATOR CONTROL SYSTEM Application February 3, 1950, Serial No. 142,322

(C1. IS7-29) 31 Claims. 1

This invention relates to elevator control systems and it has particular relation to systems wherein elevator cars are arranged in banks and wherein dispatchers are provided for dispatching the elevator cars from terminal landings in orderwill be assumed to be installed in a building having a plurality of oors or landings to be served by the elevator cars. The elevator cars operate between terminal landings or floors from which they are dispatched or started in an orderly manner. If the elevator cars are of the automatic type, the start of each elevator car may be effected by operation of a suitable starting relay. However, it will be assumed for the purpose of discussion that each of the elevator cars is started by means of a car switch under the control of a car attendant.

inasmuch as traiiic conditions for most elevator installations vary during the day, it is desirable that each of the elevator installations be suiiiciently flexible to provide optimum service for each of the trailic conditions. For example, in an oice building traflic is predominantly in an up direction during certain periods of the day. In the morning, at the start of the start of the work day, passengers are traveling primarily from the lower terminal landing or street floor to various higher landings of the building. This may be termed an up peak period. During the up peak period, the elevator` cars may be designed to operate high call reversal. As will be understood in the art, a car operating high call reversal proceeds from the lower terminal landing in an upward direction until it has reached the farthest or highest car or landing call in the up direction. When it has answered the highest call, the car reverses and returns towards the lower terminal landing. For up peak operation, the elevator cars may be permitted to start from the lower terminal landing as soon as the car is full.

During other periods of the day, passenger trafic predominantly is in a down direction. For example, in an ofce building at the close of the day, the tralic is predominantly from the upper landings of the building toward the lower terminal landing. Such traflic may be referred to as down peak traic.

If standard high call reversal operation is employed in a bank of elevator cars during a down peak, the operation of the elevator cars may not be entirely satisfactory. For example, let it be assumed that in a ten story building, a down call is registered for the seventh floor or landing just as an elevator car is starting downwardly from the ninth oor. Under these conditions, a second car may start from the lower terminal landing to serve the down call at the seventh floor. However, when the down traveling car reaches the seventh iloor, the resulting cancellation of the down call at the seventh floor results in a reversal of the elevator car which has started up from the lower terminal landing.

In accordance with the invention, the elevator cars of a bank operate on through trips between the terminal landings during the down peak period. However, an elevator car running on a through trip will be transferred to high call reversal operation if a landing call is registered in 1 a predetermined direction behind or above the minal landings is selected as the next car to leave such terminal landing. If all of the elevator cars are at one of the terminal landings, the cars are selected as the next cars to leave in a predetermined sequence.

When a iirst car is located at the lower terminal landing, and is selected as the next car to leave the lower terminal landing, it is started when any of the following conditions is fulfilled:

(l) A second car is at the lower terminal landing and a car call is registered in the iirst car.

(2) A second car is at the lower terminal landing and a landing call is registered.

(3) A second car is at the lower terminal landing and a third elevator car is approaching the lower terminal landing.

(4) The second and third cars are both conditioned for down travel and are below the upper terminal landing.

5) All three elevator cars are at the lower terminal landing.

An elevator car located at the upper terminal landing is started when any of the following conditions is fulfilled:

(l) A second elevator car is at the upper terminal landing.

(2) A second elevator car is approaching the upper terminal landing and a car call is registered in the first elevator car.

(3) A second elevator car is approaching the upper terminal landing and a landing call is registered.

(4) A second elevator car is conditioned for travel towards the upper terminal landing and a car call is registered in the first elevator car.

When the elevator cars are operating during the oii peak period, the foregoing dispatching conditions tend to separate the cars by approximately one-third of the round trip travel. If no car or landing call is registered, the dispatching action stops when two elevator cars arrive, at the lower terminal landing and one elevator car is at the upper terminal landing. Consequently, if any call is registered when the system is at rest, an elevator car serves the call within a reasonably short time.

Under certain conditions, as when all three elevator cars are away from the bottom terminal, it may be desirable to extend one of the terminal landings in order to decrease the travel of the elevator cars. For example, during the down peak operation, a resultant landing may be provided which includes a plurality of landings adjacent the lower terminal of the elevator cars. Thus, in accordance with the invention, a nine-floor building may have a resultant lower terminal landing which includes the first, second and third floors or landings. If a landing call is in existence behind an elevator` car approaching the resultant lower terminal landing and if the elevator car has no car call registered for a floor in the resultant lower terminal landing, the elevator car would stop, would reverse, and would dispatch from the third oor. This materially reduces the time required for response to calls registered behind the elevator car while it is traveling down.

The invention further contemplates the removal of any one or two elevator cars of a three car bank from service. When one of the elevator cars is removed from service, the remaining two elevator cars operate in a two-car dispatching system. If a rst one of the elevator cars is located at the lower terminal landing, it will be dispatched when any one of the following conditions is fulfilled:

(l) The second elevator car is traveling down.

(2) The second elevator car is at the lower terminal landing.

(3) The second car is at the upper terminal landing and a car call or a landing call is registered.

If a rst one of the two cars in a two-car dispatching system is located at the upper terminal landing, it will be dispatched when any of the following conditions is fullled:

(l) The second elevator car reaches the upper terminal landing.

(2) The second elevator car is traveling up in response to a landing call (if the second elevator oar is traveling up in response to a car call, the first car remains at the upper terminal landing until the second car reaches the upper terminal landing).

(3) The second car is set for travel towards the upper terminal landing and a car call is registered in the rst car.

It is, therefore, an object of the invention to provide an elevator system which dispatches a first car from a terminal landing when any of the following conditions is fulfilled:

(l) A second car is at the terminal landing and a car call is registered in the first car.

(2) A second car is at the terminal landing and a landing call is registered.

(3) A second car is at a terminal landing and a third car is approaching the terminal landing.

(4) A plurality of additional cars are approaching the terminal landing.

(5) At least three elevator cars are at the terminal landing.

It is a second object of the invention to provide an elevator system wherein a first car is dispatched from a terminal landing when any of the following conditions is fulfilled:

(l) A second elevator car is at the terminal landing.

(2) A second car is approaching the terminal landing and a car call is registered in the rst car.

(3) A second elevator car is approaching the terminal landing and a landing call is registered.

(4) A car call is registered and a second elevator car is set for travel towards the terminal landing.

It is a third object of the invention to provide an elevator system wherein the nrst of the preceding objects applies to the lower terminal landing and the second applies to the upper terminal landing of the elevator system.

It is a fourth object of the invention to provide an elevator system wherein an elevator car operates on a through trip basis until a landing call is registered on a predetermined side of at least one additional elevator car, whereupon the rstnamed elevator car is transferred to farthest call reversal operation.

It is a fifth object of the invention to provide an elevator system wherein an elevator car may be reversed and dispatched from any of a plurality of landings adjacent a terminal landing in response to a landing call behind the elevator car.

It is a sixth object of the invention to provide an elevator system wherein a first car is dispatched from a terminal landing if a second car is approaching the terminal landing in response to a landing call but not if the second car is approaching the terminal landing in response to a car call.

Other objects of the invention will be apparent from the following description, taken in conjunction with the accompanying drawings, in which:

Figure l is a schematic view in straight-line form, with parts shown in perspective and parts broken away, showing operating circuits for an elevator car.

Fig. 1A is a schematic view of relays and contacts employed in the system of Fig. l. The contacts and coils of the relays in Fig. 1A are in horizontal alignment with the corresponding contacts and coils in Fig. l.

Fig. 2 is a schematic view in straight-line form of landing call and other circuits suitable for an elevator system.

Fig. 3 is a view in elevation, with parts broken away, of elevator apparatus which may be employed in the system of Fig. l.

Fig. 4 is a schematic view of a stepping relay which may be employed in an elevator system embodying the invention.

Fig. 5 is a schematic view in straight-line form showing certain control circuits for the elevator system embodying the invention.

.'Fig. 5A is a schematic view of relay contacts and coils employed in Fig. 5. If the two Figures 5 and 5A are placed in side-by-side relationship, the corresponding relays and coils are in substantially horizontal alignment.

Fig. 6 is a schematic view in straight-line form showing control circuits for an elevator system embodying the invention,

Fig. 6A is a schematic view of certain of the relay coils and relay contacts employed in Fig. 6. If these two figures are placed in side-by-side relationship, the corresponding coils and relays are substantially in horizontal alignment, and

Fig. '7 is a schematic View of a landing call belo'w circuit which may be employed.

Although the invention could be employed for structures having any desired number of landings, it will be assumed ior the purpose of illustration that three elevator cars are installed in a building having seven iioors or landings. In the following discussion, the elevator cars will be designated as cars A, B and C. Each component associated with the car A will be identified by a suitable reference character preceded by the letter A. It will be understood that similar components are employed for the elevator cars B and C, but if the similar components are illustrated or referred to, they will be designated by the corresponding reference characters preceded by the letterBor C.

Inasmuch as the relays employed in the elevator systems may have a number of contacts, each of the sets of contacts will be identified by the reference character applied to the complete relay to which a numeral sux is applied indicating the specic set of relay contacts. Thus the designation AI 3-3 indicates that reference is made to the set of contacts 3 of the relay I3 associated with the car A. The corresponding set of contacts for the car C would be identified by the designation CIS-3. The relay contacts may be either make or front contacts which close when the relay is energized to complete a circuit, or the contacts may be break" or back contacts which open when the relay is energized'to interrupt an electrical circuit.

The following relays and switches will be referred to in the discussion:

SWITCHES AND RELAYS SPECIFIC TO CAR, A

AU-Up switch AD--Down switch AV-Speed relay Alvi-Running relay AG-Inductor holding relay AEInductor slowdown relay AF-Inductor stopping relay AT-Car call stopping relay AJ Reversing relay AS-Landing call stopping relay AW-Up relay AX-Down relay AKI-Landing call above relay AY-Landing call below relay AI I'-In service relay A I Z--Upper terminal relay AI 3Lower terminal relay AI l-High call reversal relay AH-Car call above relay AI-Car call below relay RELAYS COMMON TO ALL CARS IUR to SUR- Landing up registering relays 2DR to IDR-Landing down registering relays I-Up peak relay 2-Down peak" relay S-Upper terminal next relay 6-Lower terminal next relay K-Landing call relay.

Figure 1 A portion of the control circuits for one of the elevator cars is illustrated in Fig. 1. Since this portion is duplicated for each of the three elevator cars A, B, and C, it will suffice to illustrate and describe the portion for the car A.

The car A is secured to a flexible rope or cable A20 which passes around a sheave A2I. The sheave, together with a brake drum A22 and the armature A23A of a direct-current motor are secured to a shaft A24 for rotation as a unit. A field winding A23F for the motor A23 is connected for energization across direct-current buses L+ i, L-I. A brake shoe A25 is resiliently urged against the brake drum A22 and is released by energization of a brake coil A26. The brake coil is energized through contacts of an up switch AU or a down switch AD.

The motor armature A23A is connected in a series loop circuit with an armature A2'IA of a direct-current generator A21. A generator series eld winding A2IS may be connected in the series or loop circuit. It will be understood that the armature A21A of the generator is rotated at a constant rate by means of a motor, not shown. The motor and generator are parts of a conventional variable-voltage driving unit for the elevator car A.

The speed and direction of the elevator car A are determined by the magnitude and polarity of the energization of the main field winding AZ'IG of the generator. This eld winding may be connected across the buses L+ I, L-I through a reversing switch and a resistor ARI. The reversing switch is provided by make contacts ADI and AD3 of the down switch which when closed energize the generator eld with a polarity suitable for moving the elevator car in a down direction. When make contacts AU2 and AU3 are closed, the generator field is energized with proper polarity for up travel of the elevator car. In order to increase the speed of the elevator car, the resistor ARI may be shunted by contacts of a speed relay AV.

The speed relay AV is connected for energization across the buses L-I-I, L-I through contacts AUll or AD4 of the up or down switch. Limit switches AVTU and AVTD are opened, respectively, when the elevator car is adjacent its upper and lower limits of travel. When once energized, the speed relay AV normally is deenergized by break contacts AEI or AEZ of an inductor slowdown relay.

The up switch AU or the down switch AD is energized by operation of a car switch ASW located in the car A. When the car attendant -rotates the car switch to energize the up or down switch, a car running relay AM also is energized. Suitable contacts are associated with the up and down switches for controlling the energization thereof and these will be referred to subsequently. Safety devices A28, such as car and landing door contacts, which are closed when the various doors are closed, may be provided to control energization of the up and down switches.

The slowdown and stopping of the elevator car at a desired landing are effected by means of an inductor slowdown relay' AE and an inductor stopping relay AF. When either ofthese relays is energized, it does not operate immediately its associated contacts. Operation of the contacts is effected when the elevator car reaches an inductor plate associated with the inductor relay. The association of inductor plates with the inductor relays is well understood in the art and will be discussed subsequently.

When the elevator car is running, the energization of the inductor relays is controlled by contacts ATI of a car call stopping relay, contacts AJ I of a reversing relay, contacts ASI of a landing call stopping relay and contacts AI3-I of a lower` terminal relay. When the inductor relays are once energized, a holding relay AG also is energized to establish a holding circuit for the inductor relays.

The direction of travel of the elevator car A is determined by the energization of an up relay AW or a down relay AX. These relays are so interlocked that only one can be energized at any time.

Figure 2 landing and at each of the intermediate landings. Inasmuch as similaicircuits are associated with each of the up buttons, the circuits will be illustrated and described only for the landing buttons IU, 3U and 6U which are located respectively at the rst, third and sixth landings.

Down buttons 2D to 'ID are located respectively at the intermediate landings and at the upper terminal landing. Since these buttons have similar circuits associated with them, the circuits will be illustrated and described only for the second, third and seventh landings. The circuits associated with the up and down buttons in Fig. 2 are conventional in the art.

In accordance with established practice, each of the elevator cars has a selector associated with it. The selector for the car A has a row of contact segments Ahi to Ah6 which are engaged successively by a brush A29 as the elevator car A moves upwardly. Each of these contact segments is connected ot the bus L-l-Z when a stop is to be made at the corresponding landing. It will be understood that one of the contact segments is associated with each of the landings at which a stop is to be made when an elevator car is traveling in the up direction.

A second similar row of contact segments Acl to Ac is provided for cancelling any landing call for a landing at which a stop is made While the car is traveling in an up direction. These contact segments are engaged successively by a brush A3D.

A third row of contact segments Ag2 to Ag'I is associated with the down landing buttons 2D to 'ID for the purpose of controlling the stopping of the car in response to registration of a down call at any of the landings. These contact segments are successively engaged by a brush A3I. A row of cancelling contact segments Af2 to Afl is associated with the down landing buttons for cancelling any call registered for a landing at which the elevator car A stops during travel in a down direction. These contact segments are engaged successively by a brush A33.

Similar contact segments and brushes are provided for each of the selectors for the cars B and C and cooperate with the landing buttons in a similar manner.

Actuation of any of the up landing buttons is effective for energizing an associated one of the landing up registering relays IUR to EUR.. For example, if the button 3U is actuated, the landing up registering relay SUR is connected across the direct-current buses L+2, L-Z. The registering relay closes its contacts SURI to establish a holding circuit for itself around the button 3U and to connect the contact segments A113, Bh3 and Ch3 to the bus L2. The first elevator car to near the third oor running up completes an energizing circuit for one of the landing call stopping relays AS, BS or CS to initiate a stopping operation of the associated car at the third iloor. Shortly thereafter the associated cancelling contact segment AC3 is connected to the bus L2 to complete an energizing circuit for the cancelling coil BURN. The coils BURN and SUR are wound in opposition to each other. Consequently, energization of the cancelling call 3URN cancels the call at the third iioor.

In a similar manner, when the elevator car A is proceeding in a down direction, the landing call stopping relay AS is energized when the brush A3I reaches a hot g-segment. As the car comes to a stop, the brush A33 engages the corresponding f-segment to cancel the landing call for the landing at which the car A stops.

inasmuch as the cars stop at the terminal landings. by operation of limit switches the segments Ahl, Bhl and ChI for the lower terminal landing and Ag'l, Bgl and CgI for the upper terminal landing may be omitted if so desired.

Figure 3 Fig. 3 shows the structural relationships of the car A and associated equipment. It will be noted that the inductor relays AF and AE are mounted on the elevator car A. In addition, the car switch ASW is mounted on the car and push buttons AIC to AIC are provided on the car for registering car calls. The car A and a counterweight AWT are secured to the respective ends of the cable A20.

The inductor relay AE has lmake contacts AEI and AEZ which are normally closed. If the coil of the inductor relay AE is energized, the contacts still remain closed until the inductor relay reaches one of its associated inductor plates AUE or ADE. If the inductor relay AE is adjacent one of the inductor plates ADE, a magnetic circuit is completed for the inductor relay and if the coil of the inductor relay is also energized, the contacts AEZ are opened. If the inductor relay AE is adjacent the inductor plate AUE and the coil is energized, the contacts AEI are opened. In a similar manner, the inductor relay AF' cooperates With the inductor plates AUF and ADF.

Four inductor plates, a landing up button and a landing down button are provided for each of the intermediate landings. In Fig. 3, the inductor plates and buttons for the second floor are illustrated. When the car A approaches the second floor when traveling in the up direction and a stop is to be made at the second floor, the inductor plates 2AUE and ZAUF, respectively, cooperate with the inductor relays AE and AF to initiate slowdown and stopping of the elevator car. When the elevator car nears the second door when traveling in the down direction, the inductor plates 2ADE and 2ADF cooperate successively with the inductor relays AE and AF to initiate slowdown and stopping of the elevator car at the second landing. At the upper terminal landing, only one AUE and one AUF plate and one landing down button are required. At the lower terminal landing, only one ADE plate and one ADF plate and one landing up button are required.

The car A also has associated therewith a selector A31 which may be of any conventional construction. In the form illustrated, the selector has a plurality of rows of fixed contact segments. To simplify the illustration in Fig. 3, only two rows of contact segments Af and Ac are shown, these corresponding to the rows illustrated in Fig. 2. It will be understood that in each of the rows one contact segment is provided for each desired landing. The brushes A33 and A30 are mounted on a carriage A39 which is threaded for reception of a screw A40. Rotation of the screw in accordance with travel of the elevator car is effected by means of suitable gearing which couples the screw A40 to the shaft A24. Consequently, as the car A moves, the brushes on the carriage A39 successively engage contact segments corresponding to the landings reached by the elevator car. In addition, certain mechanical switches A4| are provided Whichlare successively engaged by a cam A43 secured toI he carriage A39. The cam has a length sufficient to bridge three successive switches. As the carriage moves, the mechanical switches are successively opened by means of the cam. These mechanical switches are employed for purposes hereinafter set forth. In accordance with conventional practice, the motor A23 and the selector A31 are installed in a penthouse above the elevator hoistway.

Inasmuch as the equipment shown in Fig. 3, with the exception of the landing buttons 2U and 2D is duplicated for the cars B and C, the description Iof the equipment for the car A sufces for the equipment associated with the cars B and C.

Figure 4 In certain of the circuits hereinafter described, stepping relays are employed. Such stepping relays are well known in the art and a typical stepping relay is illustrated in Fig. 4.

In Fig. 4, a stepping relay 5 is illustrated which includes a shaft 1. This shaft is mounted for rotation in suitable bearings and has secured thereto a ratchet wheel 8. IThe ratchet wheel is advanced by means of a suitable pawl 9 which is biased against the teeth of the ratchet Wheel. When the coil of the stepping relay 5 is energized, an armature I is attracted and such attraction moves the pawl 9 to the left as viewed in Fig. 4 against the bias of a spring ll. When the coil is deenergized, the spring l! moves the pawl 9 to the right to rotate a shaft 1 through an angle corresponding to one tooth of the ratchet wheel. If the coil of the stepping relay is intermittently energized, the shaft 1 is intermittently advanced. The shaft 1 has associated therewith a pair of contact arms A|2a and A1212 which are displaced from each other about the axis of the shaft 1 by 180. During rotation of the shaft 1, the contact arms in turn sweep over a semi-circular row A of contacts. Although only one contact is required for each of the elevator cars, conventional selector relays come equipped with rows containing a large number of individual contacts. In order to permit utilization of the standard selector relays, the contacts in a row may be arranged in groups. Thus in Fig. 4 the first contact 5A of the row A5 and every third contact 5A thereafter are connected to a common conductor. These contacts are associated with the elevator car A. In a similar manner, the second contact 5B of a row and every third contact 5B thereafter are connected to a second conductor. The third contact 5C of a row and every third conductor thereafter are connected to a third conductor. Thus three groups of contacts are provided each associated with one of the elevator cars. Since two contact arms are provided, the contact arm A|2a starts engaging the associated semi-circular row of contacts as the contact arm Al2b completes its engagement therewith. A spring arm 8a prevents reverse rotation of the ratchet wheel. It will be understood that as many rows or banks of contacts and as many contact arms as desired may be associated with the contact arms of the stepping relay. In Fig. 4 rows A5, B5 and C5 are provided respectively for the three cars.

Figure 5 In Fig. 5, circuits are shown which are common to the three elevator cars. The up peak relay I is energized by means of a manually operated switch when it is desired to condition the elevator cars for up peak operation. The down peak relay 2 is energized by means of a manually operable switch when it is desired to condition the cars for down peak operation. Direct-current energy is available for the various relays from the direct-current buses L-l-5 and L-5.

At the upper terminal landing, it is desirable that only one elevator car at a time be selected as the next car to leave the terminal landing. Preferably, the elevator cars should leave the upper terminal landing in the order of their arrival thereat. The next car to leave the upper terminal landing is determined by next or stepping relay 5. The contacts 5A, 5B and 5C of the stepping relay are associated, respectively, with contacts of upper terminal relays Al2, Bl2 and CIZ of the three elevator cars.

In a similar manner, the next car to leave the lower terminal landing is determined by a stepping relay 6 which is similar in construction to the stepping relay 5. The contacts 6A, 6B and 6C of the next or stepping relay 6 are associated, respectively, with contacts of the lower terminal relays A13, B|3 and C|3 of the three elevator cars.

In Fig. 5, a landing call relay K is employed for the purpose of indicating the registration of a call by one of the landing buttons. To this end, a series circuit 45 is provided which includes break contacts of the registering relays for the landings. The series circuit 45 includes the landing call relay K and extends between the buses L-l-5, lli-5. The circuit 45 may be traced as follows: L-l-5, 1DR2, 6UR2, BDRZ, 5UR2, 5DR2, 4UR2, 4DR2, 3UR2, 3DR2, 2U'R2, 2DR2, I URZ, K, L-5.

To conserve space, the registering relays for the third and fourth floors do not have their break contacts shown in Fig. 5. It will be understood that if any of the registering relays is energized, the break contacts therefor are opened to deenergize the landing call relay K.

The circuit 45 also has contact segments associated therewith for the purpose of indicating the position of any landing call with respect to the elevator cars. Thus the selector for the car A has a row of contact segments AaI to Aa? which have a brush A46 associated therewith. The brush A46 moves the contact segments for the various landings in accordance with movement of the car A. The brush A45 should be dimensioned to bridge two successive contact segments of its associated row of contact segments. Similar contact segments and brushes are provided for the cars B and C.

A landing call above relay AK is connected between the brush A46 and the bus L-5. Similar'- ly, landing call above relays BK and CK are associated with the brushes B46 and C46.

The connections of the contact segments to the bus L-I-S are controlled by the conditions of the break contacts located in the circuit 45.

The contact segments for each intermediate landing are connected to the circuit 45 at a point on the circuit 45 located between the break contacts for the up and down registering relays for the same landing. For example, the contact segments Aa6, BCLS and Ca are connected to a point on the circuit 45 located between the break contacts 6UR2 and 6DR2. The contact segments for the upper terminal landing are connected directly to the bus L+5. The contact segments for the lower terminal landing are connected to a point on the circuit 45 located between the contacts 2DR2 and IUR2.

Deenergization of any of the landing call above relays AK, BK or CK indicates that one or more landing calls have been registered for landings above the position of the elevator car associated with such relay.

Figure 6 Separate control circuits for each of the cars A, B and C are illustrated in Fig. 6. Although somewhat different contact arrangements are provided for certain components in Fig. 6, similar relays and lamps are employed for the three cars.

Consequently, for the preliminary discussion of Fig. 6, it will suffice to discuss the relays and lamps for the car A alone. The cars A, B and C are assumed to be representatively at the sixth, first and second landings.

An in service relay AI I is provided for the car A. When the oar A is in service, the relay AII is energized from the direct-current buses L-I-S, L-G through a manually-operable switch. When the elevator car A is to be removed from service, the switch is opened.

A row of contact segments including the segments ATI, AT2, ATS and AT'I are provided on the selector for the car A for engagement by a brush A50. The contact segments ATI, ATZ, ATS and AT1 have positions on the selector corresponding to the rst, second, third and seventhlandings.

The contact segment AT'! is connected through an upper terminal relay AI2 to the bus L-6. When the elevator car A is at the upper terminal landing and is in service, the relay AI2 is connected for energization from the direct-current buses L-I-G, L-S through the brush A50.

The contact segment Arl is connected to the bus L-S through the lower terminal relay AI3. Consequently, when the elevator car A is at the lower terminal landing and is in service, the lower terminal relay AI3 is energized through the brush A50. Under certain conditions, the lower terminal relay AI3 may be energized when the brush A50 engages the contact segments ATZ and ATS for the second and third floors. The conditions under which such energization occurs will be discussed below.

When the elevator car A is at the lower terminal landing and is selected as the next car to be dispatched from the lower terminal landing, a suitable signal is actuated, for an example, a lamp ANU is illuminated. This indicates to the car attendant that he should start loading his car. The elevator car A is started from the lower terminal landing by operation of a suitable signal such as by illumination of a lamp ASU. This lamp is connected for energization through various combinations of relay contacts which will be discussed below. As previously pointed out, the elevator cars may be operated high call reersal. Such operation is controlled for the car A by the high call reversal relay AI4.

Similar provisions are made for starting the elevator car A downwardly from the upper terminal landing. To this end, a lamp AND is illuminated to indicate that the elevator car A is selected as the next car to leave the upper terminal landing. The lamp ASD is illuminated to dispatch the elevator car A from the upper terminal landing. The lamp ASD also may be illuminated when the car A reverses at a highest call. The illumination of the lamp ASD is controlled by various combinations of relay contacts which will be discussed below.

Car calls are registered by means of the car buttons AIC to A1C for the respective landings. These buttons, when actuated are retained in actuated condition by means of windings A5I which are energized through make contacts of the up or down relay AW or AX. When the elevator car reverses these contacts are both opened for a short time to release the car buttons. The car buttons include'magnetic armatures for the windings and are spring-biased towards their opened condition. The car buttons have associated therewith two rows of contact segments Am! to Am'I and Api to A391. These Contact segments are engaged successively respectively by brushes A52 and A53. The car call stopping relay AT is connected between the bus L-B and the brushes A52 and A53 respectively through make contacts of the up and down relays AW and AX. During up travel of the elevator car, when the brush A52 reaches a hot contact segment, the car call stopping relay AT is energized to initiate a stopping operation cf the elevator car. The brush A53 is effective in a similar manner during down travel of the elevator car. The contact segments for each landing served by the elevator car are connected through the associated car button to the bus L-I-S.

The mechanical switches A4I are employed with other apparat-us for the purpose of indicating the position of a car call with respect to the elevator car. A separate mechanical switch A4I is located between each adjacent pair of the contact segments AmI to Am'l. As previously pointed out, these mechanical switches are opened successively by a cam A43 which is long enough to bridge three of the mechanical switches.

Energization of the car call above relay AH indicates the registration of a car call for a landing above the car. The relay AH is connected between the bus 1.-*5 and a brush A55 which is long enough to bridge two adjacent ones of the contact segments Aml to Am'I. The brush A55 is spaced above the brush A52 by a distance corresponding to the spacing of the Contact segments Aml to Aml.

The car call below relay AI is connected between the bus L-6 and a brush A56 which also successively engages the contactor segments Ami to Am?. The brush A56 is long enough to bridge two successive ones of the contact segments AmI to Am'l and is spaced below the brush A52 by a distance equal to the spacing of contact segments.

The cam A43 opens the mechanical switches A4I on each side of the contact segment being engaged by the brush A52. This prevents energization of the car call above relay AH through any car call button for any landing below the position of the car. In addition, the opening of the mechanical switches prevents the energization of the car call below relay AI through any car call button for a landing above the car position.

Figure 7 The landing call below relay AY when energized indicates the absence of a landing call for a landing below the position of the car. It is associated with terminal extension landings, which in the illustrated embodiment comprise the second and third lands. If employed, this relay requires the car A when traveling down, to travel to the lowest landing for which a landing call is registered even though a terminal extension is provided.

The landing call below relays AY, BY and CY cooperate with a call below circuit 62 in the same manner. Consequently, a discussion of the relay AY and its operation for the car A will suilice.

The selector for the car A has a row of contact segments Atl, At2 and At3 for the rst, second and third landings which cooperate with a brush A60 capable of bridging two of the segments. The relay AY is connected between the brush A60 and the bus L-l.

The call below circuit B2 includes break contacts IUR3, 2DR3, 2UR3 and 3DR3. The contacts I UR3 are located between the contact segment Atl and the bus L-I-l. The contacts 2DR3 are located between the contact segments Atl and At2 and the contact segments 2UR3 and 3DR3 are located between the contact segments At2 and At3.

As the car A approaches the terminal extension landings while traveling down, the brush A60 engages the contact segment At3 for the third landing. If no landing call is registered for a landing below the third landing, the relay AY will be energized to close its make contacts AYI (Fig. 6) through the following circuit (Fig. 7): L-l-l, IUR3, 2DR3, 2U'R3, 3DR3, At3, A60, AY, L-l. The elevator car A while traveling down does not reverse above the lower terminal landing as long as the make contacts AYI are open.

OPERA'I'ION--CAR A STARTS FROM LOWER TERMINAL LANDING In discussing the operation of the elevator cars, it will be assumed that the car A has been selected as the next car to leave the lower terminal landing and that the selected car has received its start signal.

When the car A previously reached the lower terminal landing, the lower limit switch A30B opened to deenergize the down relay AX (Fig. 1). The down relay consequently opened its contacts AXI to prevent re-energization of the down switch AD and closed its break contacts AX2 to energize the up relay AW. The up relay AW closed its make contacts AWI to prepare the up switch AU for subsequent energization and opened its break contacts AW2 vto prevent ener- 14 gization of the down relay. It will be understood further that the upper limit switch AVTU, ASTU and A30T are closed whereas the lower limit switches AVTD, ASTD and A30B are open. The car attendant rotates his car switch ASW (Fig. 1) in a counterclockwise direction to complete the following circuit: L-I-I, ASW', ASWI,

AWI, AFI, ASTU, AU, AM, A28, L-I.

Upon energization, the running relay AM closes make contacts AMI to prepare the inductor relays for subsequent energization. In addition, the make contacts AM2 close to establish a holding circuit around the contacts AJ2 of the reversing relay.

As a result of the energization of the up switch AU, make contacts AUI close to energize the brake coil and the brake is accordingly released. The contacts AU2 and AU3 close to energize the generator field for up travel of the elevator car. Consequently, the elevator car starts to move up from the lower terminal landing. The make contacts AU4 close to energize the speed relay AV. The speed relay closes its contacts AVI to shunt the resistor ARI. The elevator car now accelerates rapidly to its full running speed. The make contacts AUS close to establish a holding circuit around the car switch ASW and the contacts AWI of the up relay. Finally, the break contacts AUB open to prevent energization of the clown relay AX.

With the car A running up, it `will be assumed that an up call is registered for the third landing by operation of the landing button 3U (Fig. 2). Also a :car call is registered for the sixth floor by operation oi the car call .button ASC (Fig. 6).

As the car approaches the third oor, the brush A29 finally completes the following circuit: L+ 2, BURI, Ah3, A29, AW3, AS, L-2.

Upon energization, the landing call stopping relay AS closes its `contacts ASI (Fig. 1) to energize the relays AG, AE and AF. The relay AG closes its contacts AGI to establish a holding circuit around the contacts AS I.

Although the windings of the inductor relays AE and AF are energized, nothing happens until the inductor relay AE reaches the inductor plate AUE (Fig. 3) for the third floor. At such time, the contacts AEI open to deenergize the speed relay AV (Fig. 1). The speed relay opens its conta-cts AVI to introduce the resistor ARI in series `with the generator eld winding A2`IG. The elevator car now slows to its landing speed.

As the slow up-travel of the elevator car continues, the inductor stopping relay AF reaches the inductor plate AUF (Fig. 3) for the third oor and the contacts AFI open to deenergize the up switch AU (Fig. l) and the running relay AM. The relay AM opens its contacts AMI to deenergize the windings of the relays AG, AE and AF. The ycontacts of these relays consequently return to the positions illustrated. The contacts AM2 open but have no immediate effect upon the operation of the system.

The deenergization of the up switch AU results in opening of the contacts AUI to deenergize the brake coil. Consequently, the brake is applied to stop the elevator car at the third landing. In addition, the -contacts AU2 and AUS open to deenergize the generator eld winding. The contacts AU and AU5 open Ibut have no immediate eiect upon the operation of the system. The contacts AUS close but have no immediate effect on the system for the reason that the contacts AW2 remain olpen.

It will be assumed that the entering passenger amano 15. y at the'third landing also desires to gofto'the; sixth landing. 'Uponrotation of the car switch ASW by the car attendantr to engage its associated contact and upon closure of the carand hoistway doors, the up switch AU and? the car running relay AM again are'energized' andpro# duce up travel of the elevator car in the manner previously described.

As the elevator car nears the sixth floor, the brush A52 (Fig G) finally engages the contact segment AmG to complete the following circuit: L+8, AEC, Am, A52, AW'I, AT, L-S.

The car call stopping relay, upon energization, closes its contacts ATI (Fig. l) to energize thex relays AG, AE and AF. These relays initiatethe slowdown and stopping of the elevator vcar at the sixth landing in the manner previously described for the third landing. cussion it will be understood that the car attend-f ant-may manually open the car call button after' the call is answered. However, in the preferredembodiment the brush A52 leaves the contact segment AMB as the car stops and the car call button is subsequently reset by opening of the contacts AW 3 as discussed below.

After he has discharged his passengers, the car attendant again manipulates the car switch ASW to reenergize the up switch AU and the car running relay AM. The car proceeds in the up direction in a manner previously described. As the car nears the upper terminal landing, the inductor relay AE (or the upper limit switch AVTU) opens its contacts to interrupt the energization of the speed relay AV. Such deenergization results in slowdown of the elevator car in the manner previously described. The upper limit switch ASTU opens to deenergize the up switch AU and the car running relay AM. Such deenergization results in stopping of the elevator car at the upper terminal landing in the manner previously described.

As the elevator car reaches the upper terminal landing the limit switch A30T opens to deenergize the up relay AW. This relay, upon deenergization, closes its break contacts to energize the lower relay AX. However, for a short time the From the preceding dis-V contacts AW8 and AXQ are open to reset any operated car call buttons.

CAR A RETURNS TO LOWER TERMINAL LANDING It will be assumed next that the car A at the upper terminal landing has been selected as the next car to leave the upper terminal landing,

that it' has received a start signal, that a car call has been registered for the second landing and that a landing call has been registered for the third landing.

When the car reached the upper terminal landing, the upper limit switch A30T opened to deenergize the up relay AW. This relay, upon deenergization, opened its make contacts AW I to prevent energization of the up switch AU and closed its break contacts AWZ to complete an energizing circuit for the down relay AX. The cnergization of the relay AX resulted in closure of the contacts AXI to permit energization of the down switch AD and in opening of the' contacts AX2 to prevent energization of the up relay AW.

Upon actuation of the car switch ASW by the car attendant, the following circuitis established: L-i-I, ASW, AXI, AF2, ASTD, AD, AM, A23, L-I.

The energizationrofthe car runningr relayAM results in closure of the contacts AMI, AM2. and

AM3 for the purposes previously set forth.

The energization of the down switch AD results in closure of the-makecontacts AD2. rlhis .releases the elevator brake. Also contacts ADI and Ad3 close to connect the generator eld for energization with proper polarity for down travel of the elevator car. The car now starts to proceed in a down direction. Contacts AD4 close to 'energize the speed relay AV. The relay AV establishes a shunt around the resistor A-Rl to produce full speed operation of the elevator car in the down direction.

Closure of the make contacts ADS establishes a holding circuit around the car switch` ASW and the closing contacts AXI of the holding relay. Contacts ADB open to prevent energizationA of the up relay AW.

As the elevator car nears the third landing, the brush A3I (Fig. 2) finally engages the contact segment Ag3 to establishthe following energiz ing circuit: L-i-2, 3DRI, A93, ASI, AX4, AS, L-2. The contacts ASI (Fig. l) consequently close to energize the windings of the relays AG, AE and AF. The relay' AG completes its holding circuit for the inductor relay windings.

As the inductor relay AE reaches the inductor plate ADE (Fig. 3) for the third floor, it opens itsV contacts AEI to deenergize the speedY relay. As previously pointed' out such deenergization resultsv in a'. decrease in the speed of the elevator car.

When the inductor relay AF reaches the inductor plate ADF for the third floor, contacts AF2 open to deenergize the up switch AD (Fig. l; and the car running. relay AM. The car running relay AM operates as before to open its contacts AM I',

AM2 and AM3. However, the relay AX remains energized as long as' the break contacts of the' relay AI 3 are closed.

The deenergiza'tion of the down switch` AD results in the` opening of the contacts AD2 to apply the brake; and opening of the contacts ADI and AD3 to deeenergize the generator field. Consequently, the car stopsv at the third' landing. The opening of the contacts AD4 and ADS and the closing'ofV the contacts ADS have no immediate effects on the operation of the system.

During the initiation of a stop of the elevator car a't the third landing, the brush A33 'engages' the contact segment Af3 to complete'the following energizing circuit: L+2, 3DRI, 3DRN, A173', A33, AX5, AGZ, L-2. Theenergization of the canceling coil 3DRN cancels the call for the third landing.

When the car attendant again is ready to proceed downwardly, he' again operates his car switch ASW to reenergize the vswitch AD and the car running relay AM. These operate in a manner previously described to move the elevator car in a down direction.

As the elevator car nears the second'oor, the brush A53 (Fig. 6) engages the contact segment A222 for a time sufficient to complete' the following circuit: L-l-B', lA2C, Ap2',A53, AXB, AT, L-6. The car call stopping relay AT closes its contacts ATI for a. time sufficient (Fig. l) to energize the relays AG, AE andAF. These operate to stop the elevator -car at the second landing in the manner discussed with reference to the stop at the third landing.

When the car attendant is ready to proceed to the lower terminal landing, he again operates his car switch to start the car downwardly in the manner previously described. As the elevator "car nears'thel'ower terminal landing, the slow til the car C leaves the upper terminal landing. Under these conditions, the stepping relay completes the following circuit for the next down lamp for the elevator car C (see Fig. 6): L--G, C12-5, C5, CND, L-G. The car attendant for the elevator car C now is informed that his car has been selected as the next car to leave the upper terminal landing and may start to load his car. The stepping switch operates in a similar manner to select the car A or the car B as the next car to leave the upper terminal. If two or more elevator cars are at the upper terminal simultaneously, the stepping relay 5 steps until it reaches the first position capable of maintaining the energization of the stepping relay. The elevator car corresponding to such position then is selected as the next elevator car to leave the upper terminal landing.

The selection of the next elevator car to leave the lower terminal landing is accomplished in a similar manner lby the stepping relay G. This stepping relay selects one of the next up lamps ANU, BNU or CNU for illumination. The lower terminal relays A13, B13 and C13 cooperate with the stepping relay G in the same manner by which the relays A12, BIZ and C12 cooperate with the stepping relay 5. It will be understood that each of the lower terminal relays A13, B13

and C13 is energized when its associated eleva-y tor car is at the lower terminal landing.

The start up relays are controlled by combinations of relay contacts which are dependent for each elevator car on the positions and directions of travel of the elevator cars. Let it be assumed that the elevator car C is at the lower terminal landing and that it has been selected as the next car to leave the lower terminal landing. The system is assumed to be on off peak or down peak operation. Under these circumstances, the elevator car will receive a start signal under any of the following conditions:

(1) Either car A or car B subsequently reaches the lower terminal landing and a landing call is registered. Under these circumstances, one of the sets of contacts A13-8 or B13-8 is closed. Furthermore, the contacts CK2 are closed because of the existence of a landing call for a landing above the position of the car C. One of the two following circuits is, therefore, established for the start up lamp CSU:

(2) Either car A or car B subsequently reaches the lower terminal landing anda car call is registered in the car C. Again either of the sets of contacts A13-8 or B13-8 is closed and A the make contacts CHI are closed. The latter contacts are closed because of the presence of a car call for a landing above the position of the car C. Consequently, one of the two following circuits is established for the start up lamp CSU:

(3) The elevator car B subsequently reaches the lower terminal landing and the elevator car A is approaching the lower terminal landing. The presence of the car B at the lower terminal 20 landing results in energization of the lower terminal relay B13 which closes its contacts B13-I0. Inasmuch as the elevator car A is approaching the lower terminal landing, the up relay AW for the elevator car A is deenergized and its break contacts AWG are closed. Furthermore, the elevator car A has left the upper terminal landing and the break contacts A12-4 of the upper terminal relay for the elevator car A are closed. Inasmuch as the elevator car B also is away from the upper terminal landing, the contacts B12-4 are closed to complete the following circuit: (a) L-l-G, C13-6, CG, AWG, B13-10, A12-4, B12-4, CSU, 1 3, L-G. Had the elevator car A reached the lower terminal landing while the elevator car B was approaching the same landing, a circuit somewhat similar to the immediately preceding circuit would be established as follows: (B) L-I-G, C13-G, C6,A13-1, BWG, A12-4, B12-4, CSU, 1-3, L-G.

(4) The elevator cars A and B both are approaching the lower terminal landing. Under these conditions, the up relays for both of the cars A and B are deenergized and the break contacts AWG and BWG are closed. The upper terminal relays for these cars are deenergized and the break contacts A12-4 and B12-4 are closed to complete the following circuit: L+6, C13-G, CG, AWG, BWG, A12-4, B12-4, CSU, 1-3, L-G.

(5) The elevator cars A and B also are at the lower terminal landing. The lower terminal relays for the cars A and B are both energized to close their make contacts A13-I0 and B13-111. The upper terminal relays for the same cars are both deenergized and have the break contacts A12-4 and B12-4 closed to establish the following circuit: L-l-G, C13-G, C6, A13-11), B13-10, A12-4, B12-4, CSU, I-3, L-G.

When any of the elevator cars is removed from service, the associated terminal relays A12 and A13 or B12 and B13 or C12 and C13 and their associated in service relay A11, B1 I or C11 are deenergized. It will be assumed that the elevator car A is removed from service and that 1 the remaining elevator cars B and C operate as a two-car bank. The assumption that the elevator car C is at the lower terminal landing is continued. Under these circumstances, the elevator car C receives a start up signal under any of the following conditions:

(l) The elevator car B is traveling down. The upper terminal relays A12 and B12 are both deenergzed and their contacts A12-4 and B12-4 are closed. The up relay for the down traveling car B is deenergized and the contacts BWG are closed. Consequently, the following circuit is established for the start up lamp: L-1-6, C13-6, CG, A11-4, BWG, A12-4, B12-4, CSU, 1 3, L-G.

(2) Both elevator cars are at the lower terminal landing. The lower terminal relay for the car B is energized to close its contacts B13-10. Consequently, the following circuit is established: L-l-G, C13-6, C6, A11-4, B13-10, A12-4, B12-4, CSU, 1-3, L-G.

(3) Car B is at the upper terminal landing and a car call is registered in the car C or a landing call is registered. Inasmuch as the elevator car B is at the upper terminal landing, its up relay is deenergized and the break contacts BWG are closed. If a car call is registered in the car C, the make contacts CH2 of the car call above relay CH are closed. If a landing call is registered, the break contacts CK3 of the landing call above relay CK are closed. Consequently, depending on whether a car call or a down inductor relay (or the lower limit switch AVTD) opens to deenergize the speed relay AV and the car slows to a landing speed. The stopping inductor relay (or the limit switch ASTD) opens to deenergize the down switch AD and the car running -relay AM. These cooperate to stop the elevator car at the lower terminal Vlanding in the manner previously described. The lower limit switch A30B opens to deenergize the down relay AX. This relay opens its contacts AX I to prevent energization of the down switch AD. Also, break contacts AXZ close to complete an energizing circuit for the up relay AW. The car now is set for up travel. The contacts AW8 and AXS again are both'ope'ned for a time suili'cient to permit resetting'of the car call buttons.

DISPATCHER OPERATION It will be assumed initially that all three elevator cars are in service. This means that the in service relays AI I, BII and CI I (Fig. 6) vall are energized by closure of the inserviceswitches.

If the up peak and down peak switches (Fig. 5) are both open, the up 'peak and downpeak relays I and 2 are deenergized and the elevator carslpro vide 01T peak service.

If the up peak relay is energized by closure of its associated up peak switch, it opens its break contacts II--'I, I-Z and I-3 and it closes its make contacts I-4, I-S'and I-6 (Fig. 6).

The opening of the contacts I-I I-'2 and I--3 removes the start up lamps of the elevator lcars from service. Consequently, each of the elevator cars is loaded 'by its car attendant andthe car attendant leaves the lower terminal landing as soon as-hiselevator car is full.

Closure of Vthe contacts I-4, I 5 and vI--6 energizes the high call reversal control relays AIA, vBI4, and CI4. Energization of these relays places the system on standard high call reversal operation. -Each of the elevator cars during an up -trip will proceed to the highest car call'or'the highest landing call, whichever is higher. At the highest of such calls, each elevator car reverses and returns to the lower terminal landing.

The `reversing operation of the elevator cars will be understood by a brief discussion of the operation of the reversing relay AJ (Fig. 2). Inasrnuch as the 'contacts-AIA-I are closed, the reversing relay is subject to control by the up relay AW, the car call above relay AH andthe landing call above relay AK. If the car is traveling up, the contacts AWB of the up contact are-closed. As long as a car call exists for a landing above the position of the elevator car A, the break vcontacts AH3 are opened and the vreversing relay AJ cannot be energized. As long as a landing call exists for a landing above the position ofthe elevator car A, the make contacts AKS are open andthe relay AJ 'cannot be energized. However, as soon as the elevator car A reaches the highest call for service therefrom, the following circuit is completed: L-I-2, AKS, AI4-I, AH3, AJ, AWS, L-2.

The reversing relay promptly closes `its contacts AJ 4 to establish a holding circuit aroundthe contacts AKS, fAM-I and AHS. Contacts VAJ I (Fig. l) close to energize the relays AG, AE and AF to Vassurestopping of the-elevator car-at the next landing reached thereby. Contacts AJ 2 open and as soon 'as the parallel contacts -AM2 open, the up relay AW is deenergized. The deenergization of the up relay AW results in energization of the down relay This conditions theelevator car A for down travel. In addition,

the contacts AJ 3 (Fig.6) to close to illuminate the start down lamp ASD. This informs the car attendant that he is returning to the lower terminal landing. It will be understood that the-contacts AW8 and AX9, Fig. 6, are both open for a brief time to reset car call buttons beforethe car starts down.

Let it be assumed next that the up peak relay lI is deenergized and that the down peak relay 2 is energized by closure of its associated down peak switch (see Fig. 5). The energization of the down peak relay results in closure of the make contacts V2--I, 2 2 and 2-3 (Fig. 6) This places thesystem on modified high call reversal. Each'elevator car will operate high call reversal only if a landing call exists for a landing behind or above the remaining two elevator cars. For example, the energization circuit for the high call reversal control relay AM includes the break contacts BK4 and 0K4 for the elevator cars B and C. By-referenceto Fig. 5, it will be observed that if no landing call exists for a landing above the position of the car B, the landing call above relay BK is energized and the break contacts BK4 (Fig. 6) -are open to prevent energization of the high vcall reversal control relay AM. Similarly, by reference to Fig. 5, it will be observed that ifvno'landing call exists for a landing above the positionof the-elevator car C, the landing call above relay CKis energized and the contacts CKII (Fig. 6) are'open -to prevent energization of the high call reversal control relay. Under either of these conditions, the contacts -A4-I (Fig. 2)

lof the Arelay AI4 are opened and prevent energization of the reversing relay AJ. Consequently, theicar Adoes -notreverse at an intermediate landing but proceeds to the upper terminal landing. 1 l

If a landing call exists for a landing above bothof the cars B and C, the lbreak contacts BKA and 0K4 (Fig. 6) are both closed and the high call reversal control relay AI4 is energized to close its contacts AI 4-I (Fig.f2). This permits the elevator -car A to operate high-call reversal.

354 Such operation will be clear -rom the preceding discussion.

In asimilar manner, the high call reversal control relay BI4 (Fig. 6) is controlled by break contacts AK4 and CK5 for the cars A and C.

'Also, the high call reversal control relay CI 4 is controlled by break contacts AKS and BK5 for the elevator cars A and B. Consequently, when the system is conditioned for down peak operation, each elevator car operates high call reversal only ifa landing-call exists for a landing above the positions of the remaining two elevator cars.

The selection of an elevator car as -the Vnext carto leave a terminal landing now will 'be discussed. Let it be assumed that the elevator car C reaches the upper terminal landing. Under such conditions, the brush C50 (Fig. 6) 'engages the contact segment CrI vto energize the upper terminal relay CIZ. This relay closes'its make contacts CIZ-I, CIZ-2 (Fig. 5) to complete the following energizing circuit for the stepping relay 5: L-I-5, 5-I, CIZ-2, 5, L-5. It will be understood that the break contacts 'I5-I of the stepping relay contacts are opened each time the stepping relay is energized. Consequently, the stepping relaynotches forward one step-at a time until the contact arm CI2a completes the following circuit for'the stepping relays: L-I-5, C5, CIZ-I, CIZ-2, 5, -L-'5.

The stepping relay n'ow'remains -energized un- 2i landing call is registered, one of the following circuits is completed:

(a)l irl-6, vCH3-Ii, C6, All-4, BWG, AII-2, C1312,

CSU, |--3,^L-6.

(bimbe, cl3-6, C6. Ali-4, iBW, AA11-iz, 0K3,

CSU, I-3,-L`-B.

Isf the car B were removed from the service in place 'of the car-A, similar circuits would be established -for the lstart upk lamp CSU. `It is believed that these circuits may be traced on the drawings as the result ofthe foregoingfdiscussion.

AIt will be understood that similar combinations of yrelay contacts are effective for illuminating the start up lamp BSU orgthestart up lam'p ASU of the cars B and A `in a similar manner. Inasmuch as vthe vcontacts Aare clearly labeled in Fig. 6, it is believed that the correspondingcircuits for the cars A and B may be traced readily v'as a result of the detailed discussion of the voperation of the start up lamp CSU.

(l) If theelevator car Asubsequentl-y arrivesA at theupper terminal landing, it energizes itsup terminal relay A|2 to complete the rfollowing circuit for the, start down lamp CSD: -L-l-S, Chi-5, C`5,-AI-2'I, CSD, L-6. n

(2) If the car vB subsequently arrives at the upper terminal landing, the following energizing circuit. is similarlyestablished: `L-H, `CII-2 5, C5, BIZ-1, CSD, L-6.

(3) (a) Ii'v the elevator car B is set for up travel, the down relay BX is deenergized and the break contacts BX'I are closed. If the elevator car B has left the lower terminal landing, the lower terminal relay BI3 is deenergized vand the break contacts BI3-I2 are closed. If a landing call has been registered, the landing call relay kK vls deenergiz'ed and lthe break contacts K6 `are closed toestablish the following circuits: Lal-6, Gli-45, C5, BXI, BII-G, BI3-I2, K6, CSD, DQS.

1(11) 'If the car A instead of the car B had beenrunnin'g up, the following circuit would be vsimilarly established: L-l-S, CIZ-5, C5, AX-l,

'(4) (a) If the elevator car vB is at the ylower terminal -landing or is set for up travel, the downy relay BX is deenergized and lthe `break contacts BX'I are closed. Under these circumstances, lf a car'call is registered in the elevator'car C, the car call below relay CI is energized to *establish the following circuit: L-l-B,

The y'start 'down lamp for the car C 1 when the car C is at the'uppe'r terminal landing is illuminated in the same manner discussed above except Vthat the car A is 'no longer effective for dispatching the elevator car C. It should be noted that when the car A is removed "from service, the contacts AII-6 are opened by 'the deenergization of the in service relay to prevent completion of a circuit therethrough for 'the start lamp of the velevator ca'rC.

It should be noted that when the elevator car B ls traveling vup for 'a landing call, the car`C is promptly dispatched. However, if the elevator car vB is traveling up in response only toa car callin the elevator 'car-B, the car C is not ldispatched vfrom 'the upper terminal landing until the arrival of the elevator car Bther'eat. If no landing callis registered, it is clear that no -intending passenger `is awaiting service 'fat la 'landing and -there is no need for prornpt dispatch of the elevator 'car C.

Thestart down vlamps for the 'cars A and iB are illuminated in a fmannersimilar to 'that described for the elevator car C. Since the 'various contacts "are vclearly labeled 'in Fig. 6, it is believed that the Vcircuits for the start-'lamps AASD and BSD-may be traced on the drawing in conformance with the discussion for the elevator car C.

Under some circumstances, rit maybe desi-rable to `extend one of the terminal landings to include a `plurality of landings adjacent the terminal landing. For example, `in an installation which has unusually 'heavy trafiic in a down direction during a down peak period from the higher landings, it may be desirable -to reverse a down traveling elevator car at a landingabove thek lower terminal landing yif complete travel of the elevator car to the lower terminal landing is not required. A terminal extension may be provided selectively in the elevator system herein described by operation of a manual switch ATE, ABTE or CTE (Fig. 6) foreach 'of the elevator cars. Under certain conditions, this Vswitch connects the contact segments Ar2, etc., for landing adjacent the lower terminal landing to the contact segment Ari for the lower terminal landing. Under these circumstances, the contact segment ATZ, etc., 'operate as -part of a resultant terminal landing and any of vthe K contact segments so connected is effective for stopping .and reversing the associated down traveling elevator car if further travel of the elevator car in a down direction is not required. As many contact segments as desired may be connected to the contact segment ATI. However, `in the embodiment herein illustrated, two segments Arz and A73 are arranged for connection to the contact segment Arl.

The vconnection of the contact segments A72 and Ar3 to the contact segment ATI is controlled by .break contacts AKI of the landing call above relayand break contacts AI3 of the car call'belownrelay and make contacts AYI of the landing call below relay AY. In addition, a further control is exercised Aby make contacts AXIE! of the down relay AX. Consequently, if the 'switchfA'IE is closed, if the-elevator car Ais -travelingdownwardly (make contacts AAXIIJ are closed), if no car call exists for a landing vbelow the elevator car A (break-contacts AI`3 areclosed), il' a landing 'call 'exists 'for a landing above the elevator car A (break contacts AKI are closed), and if there vis no landing call `for a landing below the car (contacts AYI 'are closed), the contact segments A'r2 and A13 are connected to the contact segment ArI. When the down traveling elevator' car A reaches the iirst of these connected contact segments, the brush A50 completes an energizing circuit for the lower terminal relay AI3 which may be traced as follows: L-I-S, in service switch, A50, Ar3 or Ar2, AKI, A13, AYI, AXIU, ATE, AI3, L-6.

Upon energization, the lower terminal relay AI3 closes its contacts AIB-5 to establish a holding circuit around the brush A50, the contact segment Ar2 or ATS, the contacts AKI and the contacts A13.

By reference to Fig. 1, it will be observed that energization of the lower terminal ielay AI3 results in a stopping operation of the elevator car. The switch ATE is a two-pole switch which is effective in part for controlling the connection of the contacts AI3-I to the relays AG, AE and AF. If the switch ATE is closed and the lower terminal relay AI3 is energized, an energizing circuit for the relays AG, AE and AF of the down traveling elevator car is completed through the contacts AI3-I and the switch ATE. The relays AG, AE and AF cooperate to stop the elevator car at the next floor reached by the elevator car. This will be assumed to be the third floor corresponding to the contact segment Ar3 of Fig. 6.

The energization of the lower terminal relay AI3 also opens the break contacts AI 3-2 (Fig. 1). As the car stops, the contacts AM3 open to deenergize the down relay AX. Upon deenergization, the down relay AX closes its break contacts AX2 to energize the up relay AW. The elevator car now is conditioned for travel in an up direction. Under these conditions, the second and third landings in effect form an extension of the lower terminal landing and operate in the same manner to stop, reverse and start the elevator car A.

THROUGH TRIP OPERATION In order to make certain that the operation o the elevator system is fully understood, a number of typical operating conditions will be discussed. For the rst operating condition, it is assumed that the system is arranged for off peak operation. This means that the up peak and down peak relays I and 2 are deenergized. It is assumed further that the terminal extension switch ATE is open. The elevator car C initially is at the lower terminal landing and the stepping switch 6 has stepped to a position wherein the next up lamp CNU (Fig. 6) is illuminated through the circuit: L-I-6, CI3-6, CS, CNU, L-B.

The elevator car A is at the upper terminal landing and the elevator car B is running down. For the assumed conditions, the in service relays AI I, BII and CII are energized. The lower terminal relay CI3 also is energized. The up rela-y CW and the down relays BX and AX are energized. lThe upper terminal relay AI2 is energized. Inasmuch as it is assumed that no landing call is registered, the landing call above relays AK, BK and CK and the landing call relay K all are energized.

The elevator car A now leaves the upper terminal landing and the brush A50 (Fig. 6) consequently leaves the contact segment Ar'l to deenergize the upper terminal relay AI2. The upper terminal relay AI2 now completes the following energizing circuit for the start lamp of the elevator car C: L-I-B, CI3-6, CS, AWB, BW", AI2-4, BIZ-4, CSU, I--3, L-S.

In response to his start lamp, the car attendant starts the elevator car C from the lower terminal landing by the procedure above set 24 forth. As the elevator car leaves the lower terminal landing, the brush C50 leaves the contact segment CrI to deenergize the lower terminal relay CI3. As a result of such deenergization, the contacts CI3-6 open to deenergize the lamps CNU and CSU.

Next it will be assumed that the elevator cars C and B both are at the lower terminal landing and that the stepping switch 6 has operated to select the elevator car C as the next car to leave the lower terminal landing. The elevator car A is at the upper terminal landing. The in service relays AI I, BI I, CI I, the lower terminal relays B I 3 and C I 3, the upper terminal relay AI 2, the down relay AX and the up relays BW and CW, are all energized. Inasmuch as it is assumed that no landing call is registered, the landing call above relays AK, BK and CK and the landing call relay K all are energized.

If the elevator car A leaves the upper terminal landing, the brush A50 (Fig. 6) leaves the contact segment Ar'I to deenergize the upper terminal relay AI2. The deenergization of the upper terminal relay completes the following circuit for the start lamp of the elevator car C: L+6, CI3-6, C6, AWE, BI3-I0, AI2-4, BIZ-4, CSU, I-3, L-G.

Upon receipt of his starting signal, the car attendant starts the elevator car C in an up direction by the procedure previously set forth. As the brush C50 leaves the contact segment CrI, the lower terminal relay CI 3 is deenergized to extinguish the lamps CNU and CSU. Inasmuch as the elevator car B remains at the lower terminal landing, the stepping relay 6 steps to a position wherein the elevator car B is selected as the next car to leave the lower terminal landing. Consequently, the following circuit is established for the lamp BNU: L-I-I, BI3-E, B6, BNU, L-I.

DOWN PEAK OPERATION It is assumed next that the down peak switch is actuated to energize the down peak relay 2. It is assumed that the elevator car A is at the lower terminal landing and the elevator car C is traveling down. The elevator car B has just left the lower terminal landing and the elevator car A has been selected as the next car to leave the lower terminal landing. The down peak relay 2, the in service relays AI I, BII and CII, the up relays AW and BW, the down relay CX, the landing call above relays AK, BK and CK. the landing call relay K, the lower terminal relay AI3, and the lamp ANU, are energized.

At this juncture, a down call is registered from the second landing to energize the down call registering relay 2DR (Fig. 2). The down call registering relay closes its make contacts 2DRI to establish a self-holding circuit. Also, this relay opens its break contacts 2DR2 (Fig. 5) to deenergize the landing call above relay AK and the landing call relay K. inasmuch as the elevator cars B and C both are assumed to be above the second landing, the call for the second landing does not affect the energization of the landing call above relays BK and CK.

At a time when all of the elevator cars are below the sixth landing, a down call is registered at the sixth landing. Such registration energizes the registering relay SDR (Fig. 2) which closes its make contacts GDRI to establish a self-holding circuit. Also, the relay opens its break contacts BDRZ (Fig. 5) to deenergize the landing call above relays BK and CK. Consequently, the following circuit is established for the high call 25 reversal control relay AI4 (Fig. 6): L+.6, 2--l BK-4, CK-4, AM, L-6.

The relay AI4 closes its make contacts A14-I (Fig. 2) to prepare the reversing relay AJ for subsequent energization. 'I'he elevator car A now is conditioned to operate high call reversal because of the presence of the sixth landing down call behind or above the elevator cars B and C.

The elevator car C now arrives at the lower terminal landing and energizes the lower terminal relay CI3. Such energizationcompletes the following circuit for the start lamp ASU: L+6, AI3-6, A6, Cl3-1, AKZ, ASU, l-|, L-6.

The car attendant for the elevator car A now starts his car by a procedure similar to that discussed previously. As the car A leaves the lower termina1 landing, the brush A50 leaves the contact segment Ari to deenergize the lower ter' minal relay AIS. This, in turn, opens its contacts AIS-S to extinguish the lamps ANU and ASU. Since the elevator car C now is at the lower terminal landing, the stepping relayG steps untilr it completes a circuit for the lamp CNU. This means that the elevator carA C is selected as the next car to leave the lower terminal landing.

It will be recalled that the high call reversal control relay AM is energized. It is assumed that. no car calls are registered for the elevator Qar A, and the car call above relay AH is deenergized. This means that the contacts AH3 (Fig. 2); associated with the reversing relay AJ are closed.

Asy thev elevator car proceeds upwardly, the brushA A46 finally reaches the contactor segment AaE and the landing callv above relayy AK (Fig. 5) is energized. When reenergized, the relay AK closes its make contacts AKS (Fig. 2') to complete an energizing circuit for the reversing relay AJ. This relay initiates the stopping and reversing of the elevator car A at thev sixth landing by a procedure whichy has `been discussed previously. The elevator car A now returns to the lower terminal landing in a conventional manner.

Although the invention has been described with A reference to certain specific embodiments thereof, numerous modifications falling within the spirit and scope of the invention are possible.

We claim as our invention:

l. In an elevator system for a structure having terminal landings and a plurality of intermediate landings between the terminal landings, a plurality of elevator cars operable between the terminal landings for serving the landings, call registering means for registering calls for the landings, control means for stopping each of the elevator cars at landings having calls registered by the' call registering means, and farthest call reversing means cooperating with the control means in response to registration of a call for oney of the landings on a predetermined side of certain of the elevator cars for stopping and reversing at least one of thev elevator cars at the farthest landing in a predetermined direction of travel of the elevator cars for which a call is registered by the call registering means, said farthest call registering means if the registered calls are not on said predetermined side of certain of the elevator cars being ineffective for reversing an elevator car.

2. A system as claimed in claim l wherein the call registering means comprises up call registering, means and flown call registering means for -le'aeh-.ofv the intermediate landings.

3. The System 'as'clainied in claim l c ombination with selectively-operable means for rendering the farthest call reversing means eiective to reverse a car at the farthest landing in a predetermined direction of travel of the car for which a call is registered regardless of the position of the last-named call relative to the remainder of the cars.

4. In an elevator system for a structure having terminal landings and a plurality of intermediate landings between the terminal landings. three elevator cars operable between the terminal landings for serving the landings, call registering means for registering calls for each of the landings, control means for each of the elevator cars cooperating with the call registering means for stopping the elevator cars at landings having calls registered by the call registering means, and farthest call reversing means cooperating with the control means and the call registering means in response to registration of a call for a landing displaced in a predetermined direction from two of said cars for transferring the remaining car for farthest call reversal operation, said farthest call reversing means being ineffective to transfer said remaining car for high call reversal operation if the registered call is displaced in said predetermined direction from only one of the other cars.

5. A system as claimed in claim 4 in combination with selectively-operable means for rendering the farthest call reversing means eective to transfer said remaining car regardless of the position of the other cars.

6. In an elevator system for a structure having first and second terminal landings and a plurality of intermediate landings between the terminal landings, an elevator car operable in rst and second directions between the terminal landings for serving the landings, call registering means` for registering calls for either of said directions of travel for each of the intermediate landings, control means for said elevator car normally operable during a trip in said first direction for moving the car to the rst terminal landing and reversing the car at the iirst terminal landing for movement in said second direction away from the rst terminal landing to answer calls registered by the registering means, and means responsive to registration of at least one call in either of said directions by the call registering means for a landing between the second. terminal landing and the car when traveling in said rst direction 4for stopping and reversing the elevator car at one of said intermediate landings which becomes in eiectan advanced terminal landing. K

7. A system as claimed in claim 6 in combination with means responsive to operation of the call registering means for an intermediate landing between the advanced terminal landing and the first terminal landing for preventing said stopping and reversing of the elevator car at an advanced terminal landing at least until the elevator car hasv responded to said operated secondk call registering means.

8. An elevator system as claimed in claim 6 wherein the rst and second terminal landings are respectively lower and upper terminal landings, and the first and second directions are respectively down and up directions, said advanced terminal landing comprising any of a plurality of` landings immediately above the lower terminal landing which is rst reached yby the elevator car followingv said registration of a. call..

9-.n Infan. elevator. system for a structure having iirst and second terminal landings and a plurality of intermediate landings between the terminal landings, a plurality of elevator cars each operable in first and second directions between the terminal landings for serving the landings, call registering means for registering calls for either of said directions of travel for each of the intermediate landings, control means for each of the elevator cars normally operable during a trip in said first direction for moving the associated car to the iirst terminal landing and reversing the associated car at the first terminal landing for movement in said second direction away from the irst terminal landing to answer calls registered by the registering means, and means cooperating with said control means for each of the elevator cars in response to registration of at least one call in either of said directions by the call registering means for a landing between the second terminal landing and one of the cars when traveling in said rst direction for stopping and reversing the last-named elevator car at one of said intermediate landings which becomes in eiect an advanced terminal landing.

10. A system as claimed in claim 9 in combination with a dispatcher for dispatching elevator cars from the irst terminal landing, said dispatcher being effective for dispatching one of the elevator cars from the advanced terminal cars, said dispatcher comprising means responsive to the presence of two of said cars at a first one of the terminal landings and travel of a third one of said cars away from a second one of the terminal landings for dispatching one of the cars from said first one of the terminal landings.

12. In an elevator system for a structure having upper and lower terminal landings and having landings intermediate the terminal landings,

three elevator' cars movable between the terminal landing for serving the landings, control means operable for moving each of the cars between the terminal landings, and a dispatcher for maintaining two of the cars located at the lower terminal landing and a third one of the cars located at the upper terminal landing when no demand for service exists on the system, said control means being operable for moving the third car away from the upper terminal landing, said dispatcher including means responsive to downward travel of the third elevator car and to the presence of said two cars at the lower terminal landing for dispatching one of the two cars at the lower terminal landing towards the upper terminal landing, car call registering means for each oi the cars operable within the cars for registering landings desired by car passengers, said dispatcher including means responsive to registration of a car call in one of the cars when located at the lower terminal landing and to the presence of a second car at the lower terminal landing for dispatching the car having a registered car call.

13. In an elevator system, a structure including an upper terminal landing, a lower terminal landing and a plurality of intermediate landings, a plurality of elevator cars mounted for movement between the landings, call registering means for registering calls for each of the landings, control means normally operable for moving each of the cars between the terminal landings on through trips, said control means cooperating with the call registering means for stopping the cars during such through trips at desired landings for which calls have been registered, and a dispatcher responsive to the presence of two of the elevator cars at the lower terminal landing and to the registration of a call for one of the intermediate landings for dispatching one of the elevator cars at the lower terminal landing, said dispatcher being ineffective for dispatching one of the elevator cars located at the lower landing in response only to the presence of two of the elevator cars at the lower terminal landing.

14. In an elevator system for a structure having iirst and second spaced terminal landings and a plurality of intermediate landings between the terminal landings, three elevator cars movable between the terminal landing for serving the landings, and a dispatcher comprising means responsive to the presence of a first one of the elevator cars at the first terminal landing and to the movement of second and third ones of the elevator cars towards the rst terminal landing for dispatching the first one of the elevator cars from the first terminal landing, the movement of the second one of the elevator cars towards the rst terminal landing while the third one of the elevator cars is at the second terminal landing being insufficient alone to dispatch the iirst one of the elevator cars.

15. In an elevator system for a structure having terminal landings and a plurality of landings intermediate the terminal landings, a plurality of elevator cars operable in first and second directions between the landings for serving the landings, call registering means for registering elevator calls from each of the intermediate landings, control means for each of the elevator cars, each of the control means being operable for moving the associated elevator car between said landings, and a dispatcher responsive to the presence of a plurality of said elevator cars at one of the terminal landings and to a predetermined operation of said call registering means for dispatching the car which first arrived at said last-named terminal landing.

16. A system as claimed in claim l5 wherein said call registering means is located at each of the intermediate landings for operation by intending passengers.

17. In an elevator system for a structure having terminal landings and a plurality of landings intermediate the terminal landings, a plurality of elevator cars operable in first and second directions between the landings for serving the landings, call registering means operable from the intermediate landings for registering elevator calls from each of the intermediate landings, control means for each of the elevator cars, each of the control means being operable for moving the associated elevator car between said landings, and a dispatcher responsive to the combination of the approach of one of the elevator cars to one of the terminal landings, the presence of another of the elevator cars at the last-named terminal landing, and a predetermined operation of the call registering means for dispatching said last-named elevator car from the last-named terminal landing.

averses 18. A system as Iclaimed in claim 17in combinationV with car call registering meansv operable lwith-in each of the elevator cars for registering calls desired by car passengers, ar car call registered in a first one of the cars when located at one of: the terminal landings being ineffective to dispatch the last-named car until a second approaching one of the elevator `ears substantially reaches the last-named terminal landing.

19. Inan elevator system for a structure having first and-second terminal landings and a plurality of landings intermediate the terminal landings, a plurality of elevator carseach operable in first and second directions respectively towards. the first and second terminal landings for. serving the landings, call registering means yfor registering calls for the landings, control meansfor eachof the elevator cars for stopping the elevator cars at landingsrhaving calls registered. by thecallregistering. means, farthest call reversing means cooperating with the control means in response to registration of a call for onel of the landings. displaced inthe rst direction from certain oi the elevator cars for stoppingA and reversing at least one of the elevator `,cars when traveling in the first` direction. at, the farthest landing for which a call is registered' by the call'registeringr means, said farthest call' reversing'means if lthe registered calls aredisplaced in the second direction from certain of the elevator cars beingineiective for reversing anelevator car, means cooperating with'. the, control means for stopping and reversing each, ofY the elevator. cars when` traveling in the second direction at the second terminal landing,r and means responsiveto registrationof at least one call by the call registering means fora landing between one of the cars traveling in the second direction andthe rst terminal landing for stoppingv and reversing the last-named elevator car at an intermediate landing which in effect becomestemporarily an advanced second terminal landing.

20. A system as claimed in claim 19 wherein said pluralityy of elevator carsv comprises three cars, said directions areup and down directions, saidv call registering means includes an upv call registering means and a down call registering means at each` of the intermediate landingssaid control` means normally operating to stop each of the elevator cars at each call registered by the up.. call registering means and reached'r by the car during up travel ofthe car, and said' control means normally operating to stop each ofv the elevator cars atv each call registered' by the down call registering means and reached by the car during down travel of the elevator car.

2,1. A system as claimed in claim 20 in combination with car call registering means forI registering car passenger calls for the landings, said control means comprising means cooperating with the car call registering means; for stopping the'car at landings forwhich calls are registered by the car call registering means as the landings are. reached, and means responsive to registration of. a car'callfor thesecond terminal landing. for preventing the elevator car in which the car call is registered, from reversing at an advanced second` termina-l landing.

22. In an elevator system for a structure having first and second terminal landings and a pluralityA of landings intermediate the terminal landings, at leasti three elevator cars each operable in. rstand second directions respectively towards. the first,y and; second; terminal landings the; landinssrall registering means tering calls, for the latini-ings,v control means for each of thefelevator cars for stopping the elevator cars at landings having calls registered by the call registering means, and a dispatcher for dispatching the elevator. cars` from one of the terminal landings in the order ofthe arrival of the cars at the last-named terminal landing, said dispatcher including means for` dispatching successive cars from the last-named terminal at an interval dependent only on the position of the` elevator cars, the movement of the elevator cars and the registration of calls by the call registering means.

23. In an elevator system for a structure having first and second terminal landings and a plurality of landings intermediate the terminal landings, at least three elevator cars each operable in first and second directions respectively towards the first and second terminal landings for serving the landings, call registering means for registering calls for the landings, control means for each of the elevator cars for stopping the elevator cars at landings having calls registered' by the call registering means, the pall registering means comprising landing call registering means located at each of the landings and. car call registering means disposed in each of the elevator cars, and a dispatcher comprising dispatching means which operates to dispatchone of the elevator cars designated as the selected car from the first terminal landing in response tov fulllment of; any of; the following conditions:

A. the-selected car and certain of the other` cars are atv the first terminal landing and at least one car call is registeredv in the selected car;

B. the selected car and at least a second one of the carsl are at the firstv terminal landing and atleast one call is registered bythe landing call registering means;

C; the selected car is atV the rst terminal vlandingA and atleast two of the remaining elevator cars are approaching thel first terminal landing.

patcher comprising dispatching means Which operates to dispatch one of the elevator cars designated as the selected car from the rst terminal landing in responseto fulfillment of any of the following conditions:

A. the selected car and a second one of the cars are at the rst terminal landing and a third one, of the elevator cars isv traveling towards the first terminal. landing;

B. the selected car is at the first terminal landing and at least two others of the elevator cars are traveling towards the first terminal landlng.

25. A system as claimed in claim 24- wherein the call registering means comprises landing call `registering means locatedat each of the landingsand. cal:v call registering. means 'disposed' in each of the elevator cars, saidydispatcilimg means Valsaoperating: taschen-etch the selected carin

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