US3388376A - Security control of automatic elevator cars - Google Patents

Description

June 11, 1968 J. E. MAGEE 3,388,376

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United States Patent O 3,388,376 SECURITY CONTRUL F AUTOMATEC ELEVATOR CARS John E. Magee, Greeuburgh, NSY. (191 Forest Blvd., Ardsley, NSY. H1502) Filed Apr.. 26, 1965, Ser. No. 450,793 13 Claims. (Cl. 346-20) ABSTRACT 0F THE DlSCLSURE This invention relates to control systems for one or more elevators and particularly to control sys-tems for preventing unauthorized travel of automatic elevator cars to a landing or landings.

At -the present time, in buildings serviced by elevators without attendants, non-supervised access to upper dloors of the building is provided by elevators for unauthorized persons, as well as for legitimate passengers, such aS tenants. This may be particularly undesirable during late evening or early morning hours in either otiice or apartment type structures. During such periods, stairwell access -to upper floors may be prevented by `suitable lire door arrangements. Also, service Idemands may be anticipated to be intermittent at such times, with parked elevators normally stationed at the lobby, or building entrance landing.

4It is an object of this invention to provide a control system for elevator cars which will restrict their use from a specific landing to authorized persons and detect their attempted use by -those who are unauthorized.

kIt is a further object 0f the invention t-o afford normal response of the elevators to or from demandsfat all other landings of the structure.

It is another object of the invention to provide a deterrent and alarm system to discourage attempted use of the elevators by any unauthorized personnel.

The preferred embodiment of the invention predicates dispatch or departure of an occupied elevator car from the building entrance landing on registration of demand in the car by means of a set of security call buttons. A demand is registered by utilizing an appropriate combination of suc'h buttons for a particular oor, such combination being preferably disassociated numerical-ly from the landing location number served therefrom so as to constitute a coded or combination arrangement of car call registration. The departure of an unoccupied car loccurs in a normal manner for response to landing calls at other landings. Return of lone or more cars to the building entrance landing is also provided.

The bank of security call buttons in each car is arranged such that use of one or more of certain buttons therein, not required for the security call registration, will actuate an audible or visual alarm, which may be remotely located for central station surveillance.

As an alternate arrangement for installation without means for occupancy detection the security buttons are supplemented by an arrangement for forced travel from the lobby t-o a registered hall call in the event that a `security car call is not in registration. This insures that Patented June ll, 1968 ICC an unregistered passenger in that car, -that is, a passenger who has not registered a call, will be delivered t-o the tloor of the hall call, subject to surveillance. In addition, the door operating mechanism is controlled to retain closing force sufficient to prevent their being opened manually during such restricted travel.

Features and advantages of this invention will be apparent from the foregoing and from the following description of the preferred. embodiment thereof which should be considered in conjunction with the accompanying drawings in which:

FIGS. 1 and 2 are simplified, schematic wiring diagrams showing the modiication of the control circuits shown and described in my co-pending application Ser. No. 209,564, filed July 13, 1962, and entitled, Segregated Demand Controls for Elevator Systems, required to adapt such circuits to the use of the present invention;

EFIG. 3 is a simplified, schematic wiring diagram of control initiating and car responsive circuits used with the invention;

FIGS. 4 and 45 are simplified, schematic wiring diagrams of portions of the security button arrangements for a single car; and

FIGS. 6 and 7 are simpliiied, schematic wiring diagrams of an alternative embodiment of 4the invention, shown for one car.

The invention will be described, for convenience, as a control system for a three car group of elevators. For simplification in description and illustration it will be described as applied in conjunction with the control system shown and described in my co-pending patent application Ser. No. 209,564, filed July 13, 1962 and entitled, Segregated Demand Control for Elevator Systems (hereinafter called the reference system), utilizing the same diagram conventions as outlined therein. Circuits shown herein designated FIGS. 1 and 2 will be seen to be portions of `FIGURES l and 2 of said application, each as modified by this invention. FIGS. 3, 4 and 5 herein constitute circuitry of the preferred embodiment which is in addition to the circuits shown and described in said application. `In certain of the drawings additional contacts of switches of the reference system are used, and in each case the switch identifying letters of the reference system are used in the present drawings with a new higher contact number applied as a suiX. To further clarify new components of the preferred embodiment, each such new component is identified by the pre- X letters SC, except for the security buttons which are identified by the preiix SB. To simplify the disclosure, all circuits other than those of FIGURES l, 2 and 3 are shown for car a only, it being understood similar circuitry for cars b and c will apply the invention to those cars.

Actuation of the switch SCKS (FIG. 3) initiates the control system of the invention. Switch SCKS may be by key, or clock, actuated, such as at the time of termination for the night of direct building supervision. Its closing energizes group switch SC. Contacts SCI closed thereby, thru ML3 contacts, closed in conjunction with each associated cars location at the lobby, permit operation of the specific SCC switches and illumination of the parallel SCL indicators to signal use of the security car button system for service from the lobby.

Opening of contacts SC2 (FIG. 1) and SC3 and SCF', (FIG. 2) respectively, causes isolation of certain controls of the reference system. Contacts SC3 opening erase dispatch timing control of lobby departures on the presumption that traffic is intermittent. Contacts SC2 opening prevent dispatch control by a lobby landing call. Contacts SC4 opening void operation in the reference system which is predicated on a number of up landing calls, such calls not being anticipated in conjunction with periods of application of this invention.

assasrs Contacts SCCla (FIG. 1) `opening isolate dispatch control by a lobby car call through intermediate action of CKa switch. It is to be understood that similar SCClb and SCClc contacts (not shown) exercise a similar prevention of control for cars b and c, respectively, when positioned at the lobby landing.

Contacts SCC2a (FIG. 1) closing and contacts SCCSa (FIG. 2) opening, respectively, render control of car starting from the lobby dependent on being unoccupied because of the SCO contacts, or if occupied, dependent on the registration of a recognized demand in the car, by way of CK contacts. This recognized demand will be shown later to involve appropriate use of security call buttons in the respective car.

Mechanically actuated contacts SCOIa (FIG. 1) and SCOZa (FIG. 2) are actuated in a conventional way to detect occupancy of the car, such as by responsive movement or deflection of the car platform in a manner commonly applied in the art. Presence of a passenger closes SCOla contacts and opens SCOZa contacts. In the absence of a registered recognized demand in the car, contacts CKSa (FIG. l) remain closed and contacts CKda (FIG. 2) of the CK switch remain open. Setting of switch SRa is thus restricted by circuits of FIG. 2, and its reset status is sustained in FIG. 1 circuits thru closed SCCZa, SCOIa and CKSa contacts. Registration of a recognized call will be seen later, to actuate reference switch CKa, opening its CKSa contacts to isolate SRa reset winding and closing its contacts CK6a to permit setting SRa for car starting subject to closed status of WBXZa contacts and NTI@ contacts (FIG. 2). In the absence or an occupant in the car, open SCOIa contacts isolate the reset circuit of FIG. 1, and closed SCOZa contacts of FIG. 2 permits dispatch of the car independent o-f status of Clint contacts. This permits the unoccupied car to start up from the lobby to respond to landing calls at upper oors.

Open SCC-'ta contacts (FIG. 1) can be seen to render all upper door conventional car call registration contacts ineffective. Sustaining eiect of car call switch self-holding contacts I2C2a thru TCZa, however, is not affected. Security button ISBIfz (FIG. 1) is connected in parallel with the conventional lCBa button contact to permit energization of circuit connection mC. This connects to the same circuit designation mC of FIG. 4.

FIG. 4 includes circuitry for the security car call registration arrangement of the invention. With contacts SCCSa closed, the circuit is prepared for actuation of each car call switch in car a in response to actuation of an appropriate sequence of three security buttons. As stated, lead mC of FIG. 4 connects to lead mC of FIG. 1. Also, any eight of the points, ma through mj of FIG. 4 are cross connected to the eight points m12 thru mT of FIG. 1 in any predetermined desired arrangement. For example, assume it is elected to connect me to m18 and mf to m12. Recognition of a lobby passengers demand for service to the eighteenth landing would necessitate operation of button 1SB1a of FIG. 1 followed by actuation of security buttons 13SB1a and ISSBIU, i.e., 1-13-16. For service to the twelfth landing ISBla followed by 17SB1a and 18SB23 would be required, i.e., 1-17-18. For example, the circuit for the eighteenth o'or arrangement would be from the positive power feed through lSBla, sustained by then operated IClla, through connections mC, thru closed SCCSa contacts, through operated security button contacts 13SB1a and IGSSBIa, from the me connection to the m18 connection and through resistor RISCa to actuate switch 18Ca of the reference system. Switch 18Ca is then sustained through its 18C2a contacts. Contacts 18C1a closing in FIGURE 1 of the reference system can be seen to result in actuation of switch CKa. Contacts CKSa and CK6a, as described above, permit car starting and SRa setting, independent of occupancy detecting of SCOIa and SCOZa contacts.

It may be seen that the full complement of security buttons, 128B through TSB, is not required for call regl istration. For the elected arrangement buttons 148B are thus excluded. In FIG. 5 through closed SCCoa contacts, buttons 14Sl3la and TSBla or either of them, when actuated, cause energization of alarm SCBa. Alarm SCBa may be audible or visual and preferably would be located remotely such as in a superintendents quarters or a security service central station.

It is obvious that other arrangements of buttons may be used, by transposition. Specific applications of buttons ISBIQ, ISSBIa, l'SEa or Ill-SBM and TSBla may be interchanged with others of the group. Also, instead of a separate set of security buttons (SB buttons), chosen for simplification of the disclosure, the contacts thereof may be added to and operated by the conventional car buttons IZCBa through TCBa. Extra contact buttons also can permit an expanded number of combinations avaiiable, if desired. It will also be apparent to those skilled in the art that magnetically held buttons which are old in the art can permit sequential button operation.

For installation in which the occupancy detection conftrol of SCO contacts is found inconvenient these contacts and their associated SCC and CK contacts of FIGS. 1 and 2 may be omitted. As an alternate arrangement circuits of FIGS. 6 and 7 would then be utilized. Contacts MLS would be arranged to remain closed until after their associated BVBa brushes, of FIG. 2 of the reference system, separated from their MVB contacts upon departure of cars from the lobby. Without a recognized car call demand contacts CK7a of FIG. 6 would be closed. In such case, car a in traveling up, contacts UPlla closed, from the lobby would permit contacts VBBa to close 'before contacts SCC7a opened, to thusset SCXa switch. Switch SCXa would remain set until car a approached its first landing call stop at which time contacts XSBa, of the reference system XS switch, close to complete a circuit through closed SCXIa contacts for reset of SCXa. During this period of car travel contacts SCXZa and SCXSa sustain closing excitation of door motor armature DMAa and contact SCXa strengthen the door motor eld excitation to aiford sumcient torque t-o prevent manual opening of doors by an occupant. During the sametravel period, open contacts SCXa of FIG. 1 prevent stopping in response to any non-security car call. Surveillance by the entering landing passenger is thus afforded at the upper landing stop.

To facilitate an understanding of operation of the invention as applied to a group of elevators, assume cars a, b and c of the reference system are arranged for response according to the invention herein disclosed and that all are parked at the lobby building entrance level designated as the first landing. With security control switch SCKS assumed closed, switches SCCa, SCCb and SCCc will be actuated. Assume car a is the car selected as next lto leave, with WBa switch of the reference system energized, and a person enters that car who is unfamiliar with use of the security button arrangement. Such occupancy actuates contacts SCOIa to closed status and SCOZa to their open condition. Assume then that a landing call at an upper landing is registered. In :the reference system switch UDB will then be seen to operate followed by switch SI, the SIZ contacts of which interrupt excitation of switch T coil. With SC3 contacts, FIG. 2 separated, switch T drops without the capacitive delay of condenser CIT. Contacts T1 closing energize switch WBXa through WBSa contacts. Contacts WBX2a close without effect since open SCC3a and open SCOZa contacts of FIG. 2 render that circuit inoperative at this time, with CK6a contacts also separated. If landing call response had been initiated to set SRa prior to entrance of the lobby passenger, closing of SCOIa contacts, FIG. 1 would result in reset of SRa through closed SCCZa and CKSa contacts.

'Upon operation of WBXa, reference system FIG. 2, its WBX3a contacts separate to release switch WBa. Contacts WB3a and WBta then close to permit selection of another car. Assume this is car b in which event WBb operates.

sassari@ At this same time open WBXla contacts cause release of switch SI which closes `contacts SI2 permitting reenergization of switch T, thus opening contacts T1. This defers operation of switch WBXb although WBSb contacts are closed.

After a ybrief period the retentive charge of capacitor CWBa is dissipated to permit release of WBXa switch. Its normally closed contacts WBXla close to complete a circuit thru still closed UDBI contacts to operate switch SI again, in turn again releasing T switch. Contacts T1 'closing now c-omplete a circuit thru closed WBSb contacts to operate WBXb switch. Contacts WBXZb closing, in conjunction with closed SCO'Zb contacts, in the circuit for that car similar to that of car a in FIG. 2, permit dispatch of the unoccupied car b to service the assumed upper 'landing call.

It is thus seen that a lobby passenger entering car a who is not familiar with the security button combination method of registering demand is excluded from service to upper floors even if a concurrent landing demand exists above. The occupied car loses selected `status and a next selected car responds to the landing call, presuming such second car is unoccupied. It is also apparent that if car a were not occupied its closed SCOZa contacts would have permitted its dispatch for response to the assumed upper landing call when contacts WBXZa, FIG. 2, closed.

it is readily seen in FIG. 1 that with SCC4a contacts open, use of the conventional button contacts will be ineifective. Also from FIG. 4 it can be seen that use of a single security button associated by number with -a desired destination will likewise be ineffective. Further, from FIG. 5, it is seen that indiscriminate use of security buttons by non-authorized persons will in the case of certain of the buttons, such as 14SB1a and TSBla sound an alarm for surveillance purposes.

Assume now that the entering lobby passenger is familiar with the system and with the specific code combination p-reviously assumed for the eighteenth landing. Assume then that immediately on entering the selected a car such person actuates security buttons ISBla and then 13SB1a and 16SB1zz. As previously described, this results in FIG. 1 of the reference application, in actuation of switch 18Ca which, through its 18C1a contacts permits operation of switch CKa. In FIG. 2 of the reference system, contacts CK4a closing are seen to complete a circuit through the closed WBIa contacts, car a selected, for actuation of switch LI. Contacts LIZ separating cause switch T to drop and close contacts Tl for actuation of switch WBXa, through WBSa contacts. Contacts WBXZa closing then, in FIG. 2, although contacts SCC3a and SCO-2a are separated, cooperate with contacts CKoa, now closed due to the recognized demand, to initiate dispatch of the a car from the lobby.

Assume now that just prior to entry of the authorized person, the previously assumed landing call had initiated dispatch of car a, its SCOZiz contacts having closed. Dispatch is deferred due to SRa reset action of occupancy actuated SCOla contacts. Registration of a recognized demand by the entering passenger causes CK contact action to again set SRa switch for dispatch for service to Iboth the landing call and the recognized car security call. Failure to register the recognized security call would result in transfer of selection to car b and detention of car a, as previously described.

In certain installations it may be desirable to operate without the occupancy detection switches, such as in a modernization of an existing elevator. A person skilled in the art can readily apply the invention to permit only an unselected lobby car (parked with doors closed) to respond to landing calls, retaining the selected car for authorized up passengers from the lobby, subject to the security car buttons. In a single car installation it may be undesirable to handicap service to upper landing calls in event of lobby car occupancy by an unauthorized person. In such cases the variation shown in FIG. 6 and FIG. 7 permits retention of the advantages of the security registration and control by insuring that in the absence of registered recognized demand forced car travel will be provided to the point of landing call. Surveillance by the waiting passenger there is thus assured. As previously described, car a ini leaving the lobby without CKa operated would establish set status of SCXa. Contacts of SCXa void stopping for car calls and maintain preventive torque against manual forced opening of doors until arrival at the point of landing call, at which point XSSa contacts of the reference operate to reset SCXa. Conversely, departure from the lobby with a recognized security call would be accompanied by separated status of CK7a contacts. Switch SCXa would not be set, normal door operation would be in effect and normal stop response to registered car panel calls would be provided. It is readily understood the last described alternate arrangement can be used in conjunction with that described for switch SCO occupancy detection.

If separate security call buttons, such as those shown in FIG. 4, are employed to establish the code required to permit a car passenger to cause the car to depart and if it is not desired to cause the car to depart for the desired Hoor after operation of the combination of security call buttons, the above described system may be modied to permit departure of a car after operation of the combination of security call buttons and then operation of the normal car call button for the desired floor. Such modification has advantages for installation in existing systems when it is not desired to modify the existing car call switches and permits the use of a single code combination for all oors. Also, such modification makes available additional security call buttons for operating the alarm, thereby increasing the probability that an unauthorized person will operate the alarm.

Said modification may, for example, be accomplished by connecting the mC lead of FIG. 4 to the positive line of FIG. 1, omitting the connection between the mC leads of FIGS. 1 and 4, and interconnecting one of the mtl-mj leads of FIG. 4 to the right hand contact of SCC4a in FIG. 1, thereby bridging the SCC4a contacts by the circuits in FIG. 4. If it is assumed that lead mj (FIG. 4) is connected to the right hand contact of SCC4a, then operation of buttons 17SB1a and 12SB2a will by-pass contacts SCC4a and operation thereafter of one of the normal car call buttons TCBa, ISCBa, etc. will cause the car to travel to the oor corresponding to the car call button operated. Any or all of the remaining switches ISSBla, 16SBla, etc. and 1SSB2a, 16SB2a, etc. in FIG. 4 may be connected to the alarm SCBa (FIG. 5) in the same manner as switch 14SB1a, so that operation of any one of the remaining switches will cause operation of the alarm. l

It is also obvious to one skilled in the art that other known forms of occupancy detection may be applied, such as photoelectric, load mat or proximity devices. Extension of control by the security buttons to other landings of car position, such as a basement garage, rather than to the lobby only, is also readily accomplis-hed by one skilled in the art. Supplementary known means may be used for sounding the alarm such as occupancy for an undue period with the car idle. Actuation of the alarm relay may also cause, in a known manner, doors to close, restrained against automatic or manual reopening. As these and other apparently different modilications of the invention can be made without departing from the scope thereof, it is intended that all matter contained in the precedin-g description or shown on the accompanying drawings be interpreted as illustrative only and not in a limiting sense.

It will be apparent from the foregoing that with one of the control systems of the invention, the use of the elevator cars by unauthorized persons for trips from the lobby or dispatching oor, or any other selected floor, t0

another iloor, is prevented and that with another con- Atrol system of the invention, unauthorized persons are prevented from travelling from the selected oor to a floor other than one at which a landing call, as distinguished from a car call, is registered. Furthermore, if buttons in the car which are not correct buttons, are pressed, an alarm will be given. However, normal, single button call registration is suliicient to provide normal service `between floors other than the selected oor or from other oors to the selected floor.

Having thus described my invention with particular reference to the preferred form thereof and having shown and described certain modifications, it will be obvious to those skilled in the art to which the invention pertains, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit and scope of my invention, as defined by the claims appended thereto.

What is claimed is:

1. An elevator system comprising an elevator car serving a plurality of landings, means for controlling the travel of said car between landings comprising a plurality of means in said car normally each manually operable 'by a passenger in said car to select a landing to which the car is to travel, control means normally responsive to the operation of each one of said plurality of means to cause said car to travel to each landing selected by a passenger, and security means comprising means for causing said control means to be responsive to the operation of said plurality of means in predetermined combinations, each combination corresponding to a selected landing, said security means further comprising means for preventing the normal response of said control means to each one of said plurality of means while permitting said control means to be responsive to the operation of said plurality of means in said predetermined combinations.

2. An elevator system, comprising an elevator car serving -a plurality of landings, means for controlling the travel of said car between landings comprising a plurality of means in said car each normally operable by a passenger in said car to select a landing to which the car is to travel, control means normally responsive to the operation of each of said plurality of means to cause said car to travel to each landing selected by a passenger, `and security means comprising means operable by a passenger in said car in predetermined combinations with said plurality of means for operating said control means, each combination corresponding to a selected landing, said securing means further comprising means for preventing the normal response of said control means to each of said plurality of means while permitting operation of said control means in response to operation of said means operable by a passenger in said car in predetermined combinations.

3. An elevator system comprising an elevator car serving a plurality of landings, car call registering means on said car, landing call registering means at said landings, control means responsive to landing calls registered by said landing call registering means and to car calls registered in a first predetermined manner by said car call registering means for causing said car to serve said registered calls, and security means comprising means causing said control means to cause said car to serve car calls which are registered in a second predetermined manner, said securing means further comprising means for preventing response of said control means to car calls registered in said first predetermined manner while permitting said control means to cause said car to serve car calls which are registered in -a second predetermined manner.

4. In an elevator dispatching and control system for an elevator car serving a plurality of landings from a dispatching landing and having means for normally causing said car to travel from said dispatching landing to said plurality of landings to provide service to demands registered by landing call. registering means at said plurality of landings and by car call registering means on said car, security control means operable to modify the travel of said car from said dispatching landing, said security control means comprising a plurality of passenger operable means on said car operable in predetermined combinations, each combination corresponding to a diiferent predetermined landing other than the dispatching landing, and means connected to said plurality of means and controlled thereby for causing said car to travel from said dispatching landing to the landing corresponding to the combination operated, said security control means further comprising means for preventing travel of said car from said dispatching landing with normal operation of said car-call registering means while permitting operation of said plurality of passenger operable means and response of said means connected to said plurality of means.

S. In a system according to claim 4 wherein said car comprises doors and door closing means for applying a normal closing force thereto, said security control means further comprising passenger controlled means operable by a passenger in said car and means controlled by said passenger controlled means and said landing call registering means for causing said car to travel to a landing at which a demand is registered and for causing said door closing means to apply an above normal door closing force to said doors in the absence of the operation of said plurality of means in one of said combinations.

6. In an elevator dispatching and control system for a plurality of elevator cars serving a plurality of landings from adispatching landing and having means for normally causing cars to travel from said dispatching landing to said plurality of landings to provide service to demands registered by landing call registering means at said plurality of landings and by car call registering means in said cars, security control means operable to modify the travel of said cars from said dispatching landing, said security control means comprising a plurality of passenger operable switches in each car operable in predetermined combinations, each combination corresponding to a different predetermined landing other than the dispatching landing, and means connected to said switches and controlled thereby for causing the cars in which they are operated to travel from said dispatching landing to the landing corresponding to the combination operated, said securing means further comprising means for preventing travel of a car from said dispatching landing with normal operation of said car-call registering means while permitting operation of said plurality of passenger operable switches and response of said means connected to said switches.

7. In an elevator system according to claim 6, wherein said car call registering means comprises a plurality of push buttons, and means further comprising means interconnecting said plurality of switches and said push buttons.

8. In an elevator dispatching and control system for a plurality of elevator cars serving a plurality of landings from a dispatching landing and having dispatching means for normally dispatching cars from said dispatching landing to said plurality of landings under control of demands registered by landing call registering means at said plurality of landings and by car call registering means in said cars, security control means operable to modify the operation of said dispatching means, said security control means comprising a plurality of passenger operable switches in each car operable in predetermined combinations, certain ones of said combinations each corresponding to a different predetermined landing other than the dispatching landing, said dispatching means being connected to said switches and controlled thereby for causing the cars in which they are operated to be dispatched from said dispatching landing to the landing corresponding to the combination operated, said security control means further comprising means for preventing dispatching of a car from said dispatching landing with normal operation of said car call registering means while permitting operation of said plurality of passenger operable switches and response of said dispatching means thereto, :and means for providing normal operation of said cars in response to operation of said landing call registering means and in response to operation of said car call registering means when the car in which the latter means is operated is at a landing other than said dispatching landing.

9. An elevator system comprising an elevator car serving a plurality of landings, means for controlling the travel of said car between said landings comprising at least three switches each manually operable by a passenger in said car without causing operation of another one of said switches, control means operable by a combination of a plurality of operated predetermined ones of said switches for causing said car to travel from one said landing to another said landing, said control means being unresponsive to operation of a number of said predetermined ones of said switches less than said plurality thereof.

10. An elevator system as set forth in claim 9, wherein said control means is responsive to a plurality of predetermined combinations of operated ones of said switches, each said combination causing travel of said car to a different landing, and is unresponsive to operation of said switches in other than said predetermined combinations.

11. An elevator system as set forth in claim 10 in which said switches are in a landing selecting group and further comprising alarm means operable by at least one of said switches other than a switch in said predetermined combinations thereof.

12. An elevator system as set forth in claim 3 further comprising alarm means responsive to the registration of car calls in other than said second predetermined manner.

13. In an elevator system according to claim 6, said security control means further comprising means in said cars operable by a passenger therein and means controlled by said last-mentioned means and said switches for causing an unoccupied car to travel from the dispatching landing to a landing at which a demand is registered upon failure of a passenger in a car to operate said switches in one of said combinations.

References Cited UNITED STATES PATENTS 1,893,332 1/1933 Lind 187--43 2,517,619 8/1950 Ainley 340-63 2,964,733 12/1960 Raju 340-63 JOHN W. CALDWELL, Primary Examiner.

NE1L C. READ, Examiner.

A. H. WARING, Assistant Examiner.

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