US2479149A - Load limit control - Google Patents

Description

Aug. 16, 1949. ARwQQD 2,479,149

- LOAD LIMIT CONTROL 2 Sheets-Sheet 1 Filed July 19,- 1946 Patented Aug. 16, 1949 Fritts Gardner Arwood, Moline, 111), assignor to. Montgomery Elevator Company, a corporation of Illinois Application July 19, 1946, Serial No. 684,645

This invention relates to improvements in load limit controls in elevating systems, and more par ticularlyto a load limit control system adapted to render the hall or-landing signaling means ineffective while the elevating system isloaded t0 the maximum desirable.

One feature of this invention is'that it provides an improved load limit control; another feature of this invention is that it provides a load limit control-Which is direct-and positive in action; a further feature of this invention is that it provides a load limit control system adapted to render the landing signaling means inefiective while the cage or other hoisting device is loaded to the maximum desirable; and yet another featureof this invention is that it provides a load limit control system particularly applicable to automatic elevator systems, as for example a selective collective automatic elevator system which is operated by the person cr'persons desiring elevator service. Additional features and advantagesof my invention will be apparent from the following specification and from the drawing, which is a wiring diagram of an elevating system including one embodiment of my inventionincorporated on two sheetsidentified as Figures 1 and 2.

The application'of Joseph F. Green'filed Feb ruary 2 1946 as Serial N0.'649,283 discloses a novelload-limit control for anelevating system, comprising an improved load-operated-switch'and actuating system therefor, and the application of Leigh M. Matthews filed May 2,1946 as Serial No. 666,553 discloses means whereby such a load operated switch may be incorporated in an elevating system to forestall overloaded operation of such system. My'invention is directed to the problem of load limit control in certain types-of elevating systems'as', for example, in elevating systems wherein signals to operate the hoisting device may be given from the landings, andparticularly in automatic elevator operation wherein no operator is employed in the cage, but operation is directed from the cage or the landings by the person or persons desiring elevatorservice.

In the past efiorts have been made to solve this problem in such types of elevatingsystems, but the devices heretofore utilized for this purpose have been subject to serious defects and disadvantages. For example, certain of the prior art devices rely upon the amount of electric current flowing in the elevator. circuit-to indicate the maximum desirable load Since this. current flow may be a function of factorsother than the load on the cage, thesedevices are. not entirely satis- V 7 Claims (Crier-34 I is mechanically operated as a direct function of factoryinoperatipm My new load limit control 55 the load on the cage,lis direct and positive in action, and may be coupled'in. an elevator system with a second load limit'switch also mechanically operated as a direct function of the-load but set to operate at a higher load limit (as the absolute overload rather than the maximum desirable load), andincorporated in the circuit in such manner as to forestall operation of theelevator system upon overload. For example, two load limit :control switches, "each of the type shown in the aforementioned Green application, and each operable as a direct'function of deformation of the cage crosshead, might be incorporated in an elevator system in accordance with my invention. The'linkingarrangement would then be adjusted to operate one of said switches at the maximum desirable load, and to operate the other of said switches at a greater load, the second switch being so connected asto forestall operation of the elevator drive means. Y r i I have devised and am here disclosing and claiming means wherein a mechanically operated load limit switch (which may be of the type disclosed in the aforementioned Green application) may be incorporated in an elevating system in such a manner as to render ineffective the landing signaling meanswhile the system is loaded to the maximum desired. While my invention may be incorporated in various types of elevating systems, it is applicable and particularly desirable in an automatic system; For example, in the conventional selective collective automatic freight or passenger elevator or dumbwaiter, automatic operation is obtained through control mean in the cage (or other hoisting device) adapted selectively to control the .drive meansto stop the cage at each landing level served, and through separate call means at eachsuch'landing to call the cage from the"up* and down direction respectively, and all stops registered by actuation of such-control means and call-means 'areaccumulated' and are made irrespective of the number or of the sequence of such aetuations,--but such stops are made. the order in which the landings are reached in each direction of travel. That is, up landing calls are answered when the cage is travelling in the .up directionand all down landing calls are answered when 'the cage is travelling in the down'direction, except in the case of the'uppermost or lowermostlanding calls which are answered 'as soon as the landings are reached irrespective of the direction of travel of the cage. My invention may" be incorporated in such a; selective collective system to render the the landing call means are for the purgose; of picking up additional load, while calls originating in the cage are for the purpose "of disharging load, the advantages of my pie'sent mvenuen m such a system will be obvious.

My invention is equally applicable to non selective collective automatic operation wherein the cage stops at all landings for which callshhive been registered by the control means operable from thecagecriby the call-means r'operablet from the landings, "but in which'tthe 'stops' are made in the :order inwhich the landings'are' reached irrespective of thedirec'tion of travel of .the cage. My 'invention'inay also be "used with other types of e'levatonsystems, slich- 'as -pi eregister" operation wherein signalsareTegfsteredin advance by control means in the cage and call means at the landings and rat the proper point=in ;the cage travel thaopera-tor =in"-the cage is notified by a signal, visual, audible, or otherwise, to initiate the stop, after which the "landing stop is ':automatio; and such'fas-sig'nal*operation wherein 'signals are-giv en-byactuationof control means operable from the-'cage and =landing's 'andctops are automatically made. in :response to such signals irrespectiveof rthe-directionrof*travel or the sequence in which these-signals "are given, but in which, the cage starts =operationonly uponactu atiQn oi-the'co ntrol means operable from the'cage.

Since incorporation of my-inventionin aselectiye collective automatic elevator system *is deirable, and since 'sucha system includes a comprehgnsive circuit having many. i ofithe :features and characteristics; oiothcr conventional elevator systems my-jnventio n will bejillustratedcin cons nectiqn w th agsei'ective, collective automaticreleator "system, :andthQ; drawing illustrates :a *simoperabie wiring diagram for such a sysci Guit Illustrated'inthe=drawlng cgrnp 'ses asel tiye collectiveautomaticoperation systein adapted ;to jserve four landings; and the bfoistinader c creas s assumed t be the second landing. Thepontrol means operable 39m. masse ii th ca l mea s? opera le from each oi the land ngs-together with their associated 9iri is..e :e.. 1ioivain Fi ure of. t w tiuei Win9 .mgws. an can. -m ns ar .i 1us tr edas cpmnris nsi ormai-iy io -p buttons w 1 ch when momentarily'closetl, actuate relays,

a hough'itwillbe,understoodthat various -deyices other than-push buttons 'maybeused. Thus the circuits utillzcd Lin Zregi'stering -cal1s :for1the cage 'to stop atthefirstdanding comprisethe control means herepshownf as-a push button l operable irom; the ca e and its associated" relay ll including two normally open contacts! la 'and ii b, v and the call means here tshown as a-' push button l2 operable from the landingkand' its associated relay I 3 jnclui ing; two normally open contacts we and -l; 3b. ,;-Obviously, -'since-the"ca'ge can only approach the firstt-landing iromfiche? directio n it is, nly necessaryifor fthefirst-iand-irf to include call means toFcall tthe'cage down.

Similarly, the circuits utilized in registering calls for the cage to stop at the second landing (where the cage is assumed to be in the drawing) include the push button l4 operable from the cage and its associated relay I5 including four normally open contacts [511, I517, I50 and l5d; the push button I6 operable from the second landing {forfcalling the icifage upftb tile"iai1i:lii1g, and its assoi'zia'tedrelay |-1 including three-normally open contacts Ila, I11) and He; and the push button F8 operable from the second landing for calling the cage down to the landing and its associated relay T9 "with three normally open contacts I9a,

I9'b"-'andt9c. 'The'fci'fcuits utilized in registering b stop at the third landing include the piishbutton 20 operable from the cage and itsassgciated relay 2i including four normally opn contacts 2la, 2Ib, H0 and 21d; the

pushbutton 22 operable from the third landing for calling the cage up to the landing and its assdoiatedzreiay flwith thiiee norniaily open'thnta ts: 23a, 13b a d :2 3 ;;"an'd ithe pu's'h "button 24 operable 'fromjhe third -landin-g for calling llhE cage :down ;tothe; landing 'and-itscassociated relay 25 with its three -;normaily open-contacts 25a, -Z-Sb and 250. The circuits utilizediin registeringicails i or the page to stop atthe fou rth landing" include the push button .:2- 6 operable gfrom the "page and its associated relay g-l with two normally open contacts 21a and ljb an-d -the: push,1b utton 2B perab e immzt i ourth le to cau-tize as'e up. to ii erla ciins an iisie sq t d re ay' 9 with 19 n rma lylo i: ta t gzlmand tab.

p "The circuit for; operating the cage. in a down liir ciioxraisoinclude i m ch n a l pe ted .f-d wa fQQ P EPQ PJ an i laa d* e t pnq erc ine he a 41119116.upifiirecimmitr sludggiba miiar Efs lQQ wtq -s isr i :Ifhe fdown gontactoi 30 operates fin conjunction withthe first Ian-ding, the "down-contactor stand the up contactor 3- 3 --cperate:incon' junction w ith the second landingythe down gontactorefig and the, upj;contactpr 34 operate in conjunction w-ithjhe thirdlanding, and t-he fu-p: contactor 35 -operates -in;conjunction with the fourth landing. Suchjcontactors are ar': ranged in -the 'conventional -manner 'such that they operatemechanioally upon movement of the cage to the-respectivelandingtocontrolcircuits insuring the proper direction ofvv :travel of *the sa a, ri sin lu a the a is suined o be atthe second landing aiid the-condown to -the ;-;fi r s t landing. --Likewise the "con tactors 3A and '3 5 ;-are yclosedgso that "the cage may -t rav e l up to the; third'an-d fourth iandi-ngs. l lo weyer the-contactor-32 iszopen since itis'impgssiblefior; the;cag e (beingat -the--second-land- -ih g) -to; travehdown to therthirdf-landing. Also the contactorsni l,-and+33 associated with the secpnd ;1 anding are;open;sinceit -is--not possibie' for the-cage totrayel either 'down "or "up to "the second landing. Upon movement-of the cage to the third land-ing, 'fqr example, the- 'contactor fl operating in conjunction -with' such "thirdiar'iding wouldopen "while; the contactor -3 l= operating in conjunction jwithidown travel to the second landing fwou'ldj 'clo'se. Tnecir cuit also iuliiues the mechanica'llyfoperated n'mltilfile stop eentactors 3,6,"31338?and39,'*contactor 36 in 'cen;ruiiction with down traifel i iaIfding-ievel and cozitactorb'l junction with dowmtravel at h'e tit d" landing lei'r'el, and' piuitipie stop ctfitactti aria ts operating i iespectiiily in c6liiufit9$n iVlth iiIZ travel atthesezlond and third landing levels; These multiple stop contactors are conventional in such a selective collective elevator system and are arranged to be normally openand to momentarily close as the cage approaches each respective landing, thereby providing that calls from such landing may be answered.

The operating circuit for the elevator system is shown in Figure 2 as connected to the apparatus in Figurel by means of the wires a through m and LI and L3, and includes the three line wires Li, L2 and L3 which lead from a' conventional source of electric power, not shown. Incorporated in the respective line wires are the fuses 40, 4| and 42 which are of heavy'amperage and each may be in the neighborhood 'of 100 amperes. Connected into the circuit between the fuses 40, 4| and 42 and the fuse 43, in line wire LI and the fuse 44 in linewire L3 is the drive means comprising a conventional three phase elevator motor 35. The relay 46 with the normally closed timer contact 46a and five normally open contacts 46b, 46c, 4611, 46c and 46 conditions the motor for operation in the "up direction and controls the circuits necessary to insure operation in such direction, while the timer 46a provides the necessary time delay for making stops at the various landings while maintaining the priority of direction of travel. Similarly the relay 41 with its normally closed timer contact 47a and its five normally open contacts 41b, 41c, llld, tie and 41 conditions the motor for operation in the down direction and controls the circuits necessary to insure operation in such direction, While the timer 41a provides thenecessary time delay for making stops at the various landings while maintaining the priority of direction of travel.

The potential relay 48 with its five normally open contacts 48b, 48c, 48d, 48c and 48 and its one normally closed contact 48a determines the operation of the motor as well as the operation of the non-stop timer 49. V This non-stop timer is a conventional timer which functions to hold the cage at any landing where it has stopped for a predetermined period of time which may besiX seconds. Since the timer is conventional it will not be described in detail except to say that when the solenoid 50 is energized it conditions the switchg5| for operation to the position other than that shown in the drawing. However, the switch does not operate immediately, but only after the predetermined time lag caused by the conventional timer, motor' or other timer apparatus. An operable selective collective elevator circuit is completed by the stop relay 52 having one normally closed contact 52a in series in a circuit controlled by the up and down relays it and M; by the mechanically operated reset switches Ha and H b; by the mechanically operated stop switch 53 which is shown inserted in line wire Ll and by the mechanically operated cage door switch 54 and the landing door. switches 55, 56, 51, and 58, one of which is operated by the door to the elevator shaft at each landing. Switches 54, 55, 56, 51 and 58 are included in the line on one side of the potential relay coil 48 so that if any one of such doors is open it is impossible to energize the potential relay coil and consequently the motor will not start. I

The normally closed mechanically operated reset switch Ha is connected through wire M to one side of relay coils l5, l1 and I9 and to line wire LI, and is in parallel ,with contact 480 of the't'potentialrelay. Such switch is arranged in either direction the switch ,'||a. momentarily opens .to allow the cage to respond to the call. Reset switch lib is similarly connected through wire K to one side of relay coils 2|, 23 and 25- and is in parallel with potential relay contact 4%, and operates toallow calls to the third landing to be registered and held.

The present invention is incorporated in such a conventional circuit as heretofore described in a manner rendering ineffective any aotuations of the landing call means while the cage is loaded to the maximum desirable through the inclusionof the non-stop relay 59 including one normally, open contact 59a and five normally closed contacts 59b, 59c, 59d, 59c and 59 the normally open load operated limit switch 60 which may be of the type shown in the application of Joseph T. Green filed February 21, 1946, as Serial No. 649,283, and the relay 6| with its associated normally open spring contact Sid and its normally closed contact 6|b. While all the contacts associated witheach other relay shown in the drawing are ganged to operate to-.

gether when the respective relay coils are ener-J gized or deenergized, contaots6|a and 6|b are arranged to overlap. Thus upon energization of the relay 6|, contact 6|a closes before contact Elb is caused to open by the link 6|o for reasons which will be hereafter described.

The non-stop relay coil 59 is connected at one side to the line wire LI by the wire 65, and at the other side to a parallel circuit, one leg of which includes the normally open non-stop relay contact 59a and (through the wire 66) the normally open relay-operated spring contact 6|a, and the other leg of which includes the wire 61, the normally open load limit switch 60, and the normally closed but overlapping contact 6|b. These .two legs of the parallel circuit are then con- Thus nected to line wire L3 by the wire 68. it will be seen that if the load on the cage in- V creases'to the point where the load limit switch with the potential relay 48, becomes energized as the circuit responds in answer to an actuation of the control means, the contact 6|a will close before the contact 6|b opens, and the non-stop relay 59 remains energized, for a circuit is completed through the second leg of the parallel circuit before the circuit through the first leg is broken. Thus it will be seen that my inventionprovides a holding circuit which will overcome any variations or ilutter'in the load limit switch due to acceleration or deceleration of the cage.

Energization of the non-stop relay coil 59 also opens'the contact 5%, thus opening a circuit including the wire 6 and contact 29?) of the relay associated with the fourth landing call means and rendering such call means ineffective.

Similarly, contacts 59d and 59 are opened, opening the circuit including the wires h andj and c nemas the contacts associatedwith the: third; landing; call means; contacti59c is -opened; opening the. circuit-including wire 2'. and thecontacts lasso-a ciatedwiththe second-zlanding ca-ll means andcontaotfific ismpen, opening alcircuit including 5g Wi-FG q 1 and contact i3!) associated. with the. first landing: call: means. Thus it Willi be seen that. energi-zation otsuch c0il-59-will render ineffecr tive: all 1 of the landing- :call means :while havingno effect upon the control meanswhich arelocated in thecage;-

ln the drawing the: cage is assumed to-besat the second landing-and-the circuit is shdwnin: a condition where the a stop switch- 63 has: just been closed allowing: current to flow: Hemline-: wire Ill through: the wire 69; the timer 49;- the solenoid 5d";- the=wire lilg and the closed contact 28w to the line wire L3; thus conditioning the switch-.51 for operation; but=the-non-interference timer so 2 has not yet .hadtime to operatethe 1 switch 5!. Assume-that: a person imthe cage: desiressto goto the :fourth landing-and act-dates the- ,pushwbutton 2 5, and that thereafter :a person onwthe. third landing actuates thepush button 24- to. call thecagedown-to thethirdlanding: Actu- 2-5.: ation-of: the push bntton: 26 in the cagewill completea circuit from line: wire Ls' through wire H; the push buttonQE, wire l2, the-'relay coil- 2?; wire 73;: contactorandwire tote linewire Ll; Energization of? relay coil 21 wil l close its-3 associated contacts 21a and 2H),: and the contact: 21mwill act. as a. holding circuit around the-pushbutton 2$;so. that.momentaryactuation of'such pushbutton is ali'that is, required. Assoon as the timer (is moves the switch 5| to the position other. thanthat shown inzthe drawing- (as, for example; six: seconds after stop-switch 53-=was closed), acircuit is also completed from line'- wireLSrtlnoughnow closed contacti'2lb; wires i5..andd, timercontactela, wirelii, up relay- 40 coil 5t; wires Hand 78,; thetimerswitch 51; wire l9; and the closed contact 52a to the. line wireiil. Energizationof ,the; up relay. coil de will close itsassociatedicontacts iiib, 50, 4601; 46c, and

567?; Thus closedzcontact 3th with its-associated leads. Stand 31 new acts as ahQlding. circuit around the timer switch 5!, and closed contacts: 452. andi iiifi which are. in series witharespectivea windingsof the motor through the wires 82 and Y 8:3,, condition, the motor to .run' in the up. 'direc- 50.

lead-18.4. including the .door switches '54, 55,. 56,- as

5] and :58, and through the potential relay coil 581.1130 linewire Ll Energization of that potential relayzcoilcloses contacts 43d, 48c and-;48j:'thuscompletingcircuits. to. the. motor from each line.-

Wire; and themotor runsin the up direction.

Energization of such. coil also closes: contacts Y. 4803116.;4817 thus forming holding circuits aroundi the reset switches flla and llbaso that calls; re latingito; the;.second and third landings will be. retainedwhenqthe cage goes by suchlandings with a; .consequent:momentary opening of suchreset ,switches. Also contact dim-is opened, thus. opening the lead it and breaking the circuittothe solenoid-50:; and;allowingthe switch 51. to return, to the position shown in the drawingand I the HOII-riIltEI'fBlEIlCB timer 49 to reset itself.

Theycage; wiil'prooeed up. to. the fourth land-e. ingrgandxwill not stop on itsnupwardtripain rep. sponse to.;th;e; actuation of :pushbutton: 24, 1 for: such pushzbutton will only :act .LtO .call the cage;

(lQWn tQ' Sllch? landing; although" closure.- ci e-the: con-tact: 48b1will: insure. that; such call is. 'notelost; but isaccumulated despite-the factith-at thezreset'z switch 1 [:b. momentarily opens. as the cage. goes. by the. landing. When the cage; hasreaehed the. fourth landingthecontahtor 35 will. be; mechanic cally opened=in the conventional manner; open:- ingtheconnectiorr between the; leads lit-and :14

and breaking 1 the. circuit to the relay 21; and when thistrelay becomes. deenelfgized; contactillb; opens, opening; the. leadlfizand breaking: the chichit:v i364. thee upfirelays 46;. and: consequently; (throughthe. contactrdfie), tether-potential delay: 48 The. resulting. closure ofi the; contact: 48d;

energizes; the solenoid; 50' and the timer again:

tafterzthe predehermindsdeifay') :moves-the-switch; 5 I' to; its. other position. and the cagesiss ready: torrespond to any acc mulate ncallse The earl em actuation: of. he push. but on. 24 now; becomes: efiectiye to cal the ca e down. o he; hird'1and :18:. in theiollowing, manner:- energization-; of; the; relayccil, 2s upon; the earlier actuation of: the pushhutton hasclosed the-.;fo '-.r rel aycon?- taets 2541,1519, 2530 and 25d-,;, and;cor-rtactv 2511-; has formed a, holding circuit around; thennsh button- 25. A-circuitdsnow-completedirom; line wire, L3 through-wire tdnon-stoporelaycontact: 59d; leadsnh an'd. Sigcontaet 25b; lead-88, clOsedn con-tactor 32* (which, closed mechanically v when r, the cage moved-above the, third landing), wirec,

timer contact dtmlead 89;, down relay, coils 4], leadsyiifl and timer-switch 51,1 lead l9; and. stop relay contact SZwtQ-Iine-Wire Lt: Errorgization of the down? relay coil-41, results in-l closure otrcontacts 43c and i'if toconditionrthel motor Ioroperation, in the. down direction-,- and; also. results; in closure- 0f contact Me which ie-inv series with the potential relay. l8-athrohghdeads 96-, t1, and 84, thus completinga circuit through such contact leads,' and door switches and the lpoe tential relay. Energizationofthe potential res. lay-operatesithe motor anddeenergizes the sole-.- noid- 50v to. resetv the. non-interference timer in. the. same. manner as heretofore explained.

The. cage proceeds down to thethird landing; and .when it approaches the: third landing; the mechanicallyoperated multiple stop contactor 31, closes, thus completing; a. circuit leadingfromline wireLS through lead .85; non-stoprelay corrtac'ts 59d. and 59], lead: J., closed con-tact 25c;-v leads .42 and 93, contactor. 31, lead M,- closed con-.- tact 47d, lead 9ft; and stoprelay =52: to. lineewi re- L1; Contact .5211 opens. upon energization 0tv therelayti and since such contact is .in series, withthe down relay-coil, 4-! (through the leads:

i9. and 8] and thecontact 41E)., suchcoll-is1 deenergized, opening, contact 4-70 which: is in. series. .with, .the :potential .relay, 48; and-shutting.- offhthe motor. This vactionxiid not takegplacewhen the cage passed the; third .landing. in :the; updirectionv because-the thentopendowrif relay-i contact 41d prevented the completiomof-alcire cuit upon the momenta-ry closing; of :contactorrfl;

At this point the selective action of the. timer:

contactsfliia. and flld-may berclearly seen... Timer: contact. 46:: is opened. ;up on' .energization ;of the; u-pj. relay coil 48; butiis; closed: through. theaction of- ,the conventional timer mechanism- 46a..-

uponsdeenelgization of such :coil and after -a:cer-

lead 16. 'Thus it will be seen that at the present point in the operation of the elevator system, until the pre-determined delay has expired it is impossible to energize the up coil because the timer contact 41a in series with such coil is open. Thus if a passenger enters the elevator on the third landing and presses the push button ill to go down to the first landing, such down call will obtain priority over a call from the push button 28 on the fourth landing provided the down call was made before the time delay expired and the timer contact 4141 closed.

The operation of my improved load limit control in such an elevator system as has been heretofore described is both simple and effective. Assume that enough of a load is placed on the elevator at the third fioor to close the load limit switch 60, energizing the non-stop relay 59 as heretofore described, that the push button It in the cage is actuated to take the cage to the first landing, and that the push button i8 at the second landing is also actuated to call the cage down to the second landing. Actuation of the push button l will start the cage down in the manner heretofore described, a circuit being completed from line wire L3 through closed contact llb', leads 95 and c, timer contact 4611, lead 89, down relay coil 41, lead 90, lead 18, the timer switch 5!, lead 19, and the stop relay contact 5211, to linewire Ll. Energization of the coil 41 will act to energize the potential relay 48 and the motor in the manner heretofore described. However, the actuation of the push button l8 from the landing will be rendered ineffective so that the cage will not stop at the second landing to take on any greater load while it is loaded tolthe maximum desirable, for when the contact 410 is closed upon energization of thecoil 41 a circuit will be completed from line wire L3, lead 96, through such contact, through leads 9} and 84 and the door switches, and through wire 91 and the relay 6! which is in parallel with the relay coil 48 and becomes energized whenever the potential relay 48 becomes energized, and the overlapping contacts Ma and Nb will close and open respectively. Since contact Gla closes-before contact Blb opens,-'and since the non-stop relay coil 59 was energized at the time the load limit switch 60 was closed, contact 59a is also closed and the non-stop relay coil 59 will remain energized through-the circuit from line wire Ll, lead 65, through'the relay coil 59, through closed contact lead 55a, lead 6 5, and through closed contact 76m and lead 58 to line wire L3. Energization of the non-stop relay coil 59 has opened the contact 59d thus opening the wire it and breaking the circuit between line wire L3 and the now closed contact I9b, rendering the call means ineffective. In the same manner contact-59b will open and open-the wireethus breaking the circuit between line wire L3 and the contact 29b which is utilized to call the cage up to the fourth landing, and the contact 590 will open, opening the connection between wires 1 and g to break the circuit including the contact [3b which is utilized to call the cage down to the first landing. It will be readily seen that such a load limit control will permit the operation of the cage in response to calls originating from the cage but will render inelfective all calls originating from the landings. It will also be seen that an additional load limit switch operative under a greater load than switch Si] may be incorporated in the manner disclosed in the prior Matthew applicatio S r al ,No. 649,249,

now. abandoned, in orderto forestall operation of the elevator system upon exceeding a predetermined load-greater than'the'load required to actuate switch 60. i I

While I haveshown and describedcertaln embodiments of'my'inventiomit is to be understood 7 1. Inanz-elevator system adapted to operate between a plurality of. landings andv including a cage. and drive-means therefor, an operating cirfcuit,=incl-udin'g operatingmeans for determining the. operation of: the; drive means, said operating meanscomprising controlmeans operable from the cage for selecting-the landings at which the drive means-Will stop. the cage, and call means operable; from a plurality'ofthe landings for calling the cage-to such, landings, both such operating means gbeing-eoperableto initiate operation .of'said drive means; .and switch means movable between two positions in accordance with the load onthe-cage, said-switch meansbeing so connected as torendersaid call means ineffective while the cageis loaded to .the maximum desirable.i.-w-;" 2.,In [an elevator system adapted to operate between a plurality of landings and including a cage andreversible drive means therefor, an operating circuit, including: conditioning means for determining the direction of operation of the drive means; operating; means for determining the operation of'saiddrive means, such operating means being connected in a circuit. selectively operable to actuate the conditioning means for up or-downoperationof the drive means, and such operating :means comprising control means operable from the cage for selecting the landings at which the drivev means will;stop the cage, and call means operable fromeachof the landings for calling the cage to such landings; and mechanically actuated switch means movable between two positions in accordance Wlthjhe, load on the cage, said switch meansbeingsoconnected as to render said call means .inelfective while the cage is loaded to the maximum desirable. .1 n an e ato s stemefien to Operate between a; plurality of;landing s and including a cage and drive means therefonfan operating circuit, including: operatingfmeans for initiating operation of the drive means, said operating means comprising contro l means operable from the cage-for selecting thelandings at which the drive; means will stop the-cage, and call means operable from more. than one of saidlandings for calling the cage to ,such' -landings;. collecting means adapte t ee mu ete-a alit f m: 91 .saiqxsontm eans, and 5? m ans whereby the 'drive means stop the cage in response to each such actuation regardless of the number and sequence of actuations; and mechanically actuated switch means movable between two positions in accordance with the load on any portion of the cage, said switch means being so connected as to render said call means inefiective while the cage is loaded to the maximum desirable.

4. In an automatic elevator system adapted to serve more than two landings and including a cage and drive means therefor, an operating circuit including: relay actuated operating means for determining the operation of the drive means, said operating means comprising control means entrain I?! operable from the: cage: to energlzsza relay for selecting thelandings at which the drive means willstopthe cagaZ-firstcaHmeansioperablafrom each landing except the lowermost landing; to energize a' relay for callingthe cage' to'. each? respective: landing from the" down direction; and

.secondcall means opembla: from each: landing except the uppermost; landing: ta energize a; relay for calling thercsgatdcachuiespective landmg .from the: up' direction collecting means adapted to accumulate a plurality ofactliationsofisaid control means and said first and second: call means; whereby the: drive means stops the cage in: response to) each: regardless of-the-number andis'cquencezot actnations; selectingi means foi controlling; this drive means: to make stops: in: response: wactliations: said: first and second call: means-mime order; isn whicnw the cage reaches the. landings? in: each direction: of travel; and mechanically meters switchzmeans movable between. are positiomsin accnrdance: with the load oa -the: saga said switch being so connected as: to render ssidiarsts and second call means: inefiectfive wane the cage is liiadiadi to? the maxnnmndesnatia autcmatie eievetcr system adaptedcto serve more than two landings and innluding' a cage and revsrsitle dawn means thei efon; operating circuit, including: conditioning means for deter-miningthe ditectiom oi 'oneratimr oft the drive means; relayactuated dic in MEWS for initiating the er the drive means, suchoperating" means sting adapted to selectively actuate thectnditiemng means: for upor down oper'aticn or" the means, and such oneratiiig means comprising central means operable from the cage to energize a relay for selecting the landings at which the" drive means" will stop the cage, first' call means eperatie from each landing except the lowennostlanding to energies relay for calling cage t0 each respective landing from the down direetim, and seen-ad call means operable train eacft landing: the uppermost-' landing t'd energize a rei'ay' for calling the cage to each respective leading from" the up direction: collecting means adapted to aeeumw latea plurality oi sameness of said means and said and second cair means, whereby the" drive means staff the cage in respon e toeacn acids-non regardless of the number and of actuatliens; selecting meansfor controlling the drive means to make stops response to activations of said first and second call meansin the order in which the cage reaches the in each directien of travel"; and metnaeieairy actuated switch means movable Between two positions in accordance with the load on any portion of the cage, said switch meanstefng so connected as to render said first and second can means inefi'eetive while the ca e is loaded to the desirable.

Gem an'elevator system adapted to operate between a pluralityofvlandings and including a cage and drive means: therefor;v anl operating circuit, including:. operating; means for. deter:- mining the. operation. ofv the. drive means, said operating means comprising control means op:- erable from the cage and; call: means; operable from. at least one of" said landings; first switch means movable between two. positions solely in accordance with the-load on the cage, said switch means being so-connected' as to render. said call means ineffective while the cage: is. loaded to the maximum desirable; and second; switch means movable between two positions in accord.- ance with. the. load on the: cage; said? second switch means beingoperable solely asa function of. a load greater than required to operate said firstrswitch means; and being so connectedas to forestall operation of: the-drivemeans while: the cage isoverloaded.: v

7. In an automatic elevator system adapted to serve a pluralityof: landings and including a cage?- and' drive means therefor, an operating circuit including: relayaictuat'ed operating means=for initiating the operation ot the drive means, said opera-tingmeans comprising: control. means 0pe'r'able-irom: the cage for selecting the: landings at-which: the drive means will stop the cage; and callmeans operable from eaclrlanding for calling the cage to each respective landing; collecting means adapted to accumulate a. plurality of actuations of said control means: and: call means, wherebythe drive means. stop the cage in: response-tor each such actuation regardless of the number and sequence of actuations; first mechanically actuated switch means movable between two" positions solely inaccordance: with the load on the cage; said: switch means being so connected as to render said; call means' ineliective while the cage isloaded to the: maximum desirable; and second mechanically actuated switch means movable: between two positiens solely in accordance with the load on theeage, said" second switch means being operated similarly to said. first switch means, but as a function of a load greater than required to operate said firstswi-tch means, and said second switch means being so connected as to forestall operation. of the drive means while thecage is overloaded.

FRITTS GARDNER ARWOOD.

REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Lee Oct. 8,, 1935

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