US1709161A

US1709161A - Morris

Info

Publication number: US1709161A
Authority: US
Publication date: 1929-04-16
Anticipated expiration: 1946-04-16

Description

April 16, 1929. R. A. WAITE ET Al. 1,709,161

CONTROL SYSTEM FOR ELEVATORS /54 l 222226 `0 FSR/ m *Ilm H5107 147 0122-/ 4o 41 A /57 @/g fa-WHW@ avi a F/af /f a. Wlf.

A s, L i mvENToRs BY ATTORNEY April 16, 1929.

R. A. wAlTE ET A1.

CONTROL SYSTEM FOR ELEVATORS 2 Sheets-Sheet Filed Jan. 19, 1926 INVENTORS Y E N non. m

beA

Patented Apr; .16, 3,929.'

estrae 'y'rajarssr ortica i.

" i intatti anYivioNn n; warring osYoNiinns, NEW Yemeniin riiANi :c: Monats; or arnes- Woon, NEW Jansen, AssieNons ro cris nnnvaron ooi/trani?, on Jnas'nir eier, v New ,inn-snif, a eonroNA'rioN orNnW anlasni'.- Y' I lcoNraoL srs'inia ronfntnvaroas.

Application tiled January 19,v y1926. lSerial ITo. 82,258.

rllie invention relatesto control systems7A and particularly to vators. y

ln electric elevator systems in which the car is broughtto a'stop automatica ly atthe landings, is important that the speed of control systems for elethe car, duringthe final stopping operations,

be reduced in aV minimum of time to a value Ytrom which an accurate stop may be made.

This is particularly true in'systems in which push button control is employed for causing the afutomaticsloiv-doivnas Well as the final stop .and intliose in which the starting of the earvis under the control of an operator While n the sloivrdownand stop is automatic.

, klt is advantageous lin such systems to employ a variable voltage direct current generator for supplying power to the elevator motor. Thecontrol ot' the lield strength must be' suoli that theE. M. F. generated may be rapidly brought toa proper value to cause theV elevator motor to run at a suitable speed trom vyvliichan accurate stop may be made, The timeV constant of the generator Yfield during the slow-down and stopping operations is an `import-ant factor, especially Where agenerator is used Whose lield has a large time constant,

Nhere poiveroperatedcar gate and hatchivay door mechanism is employed, or `Where the gate and door are manually operated, it is desirable to eilect the movementof the gate and door into open positions by the time that the car has stopped at the floor. Such operation is advantageous particularly because of the amountv of time which issaved..

` over, vthe speed of the car might be accidentally increased during the gateY and door open- "i ingoperatioii or ivliile'tlie gate and door are openivith a passenger inthe act otstepping into or out ot the car. 'A y i @ne feature ot the. invention resides in forcing-the strength oil the generator lield to suoli value as to' insurean accurate stop under varying conditions ot operation, y

Another feature is the minimizing ot the possibility'ot occurrence of excessive-speeds ,diiring'tlie period when the liatchivay door each stop is an inipoitantA jandfc'ar gate when used, might be*` partially orivliolly open.v v l Other features and advantages will become y 'apparentironi the following description and l automatic'stopping is employed, `it Will be described, by Way of illustration, as embodied in a self leveling elevator system. y l

ln the drawings :v f f vFigure 1 is a diagram oranelevator control,` system; and A Figure 2 is a schematic representatioirot `the Veleva-tor car, shoiving the arrangement ot' the car switch and ofniechanism suitableA `'tor effecting the leveling and car gate and liatcliivay door opening operations.

l` Referring to Figure 1, no attempt is made `to shoivthe coils andcontacts of the various Vcectroinagnetic switches in their associated positions, ay straight `diagram being einployed yivliereiii the coils and contacts of the various switches are separated in such manner as to rendertlie circuitsinvolved relatively simple.` Also the 'parts' of other rswitches andapparatusare separated inthe interest of simplifying'` the' diagram. For a clearer understanding ot' the invention, the stationary contacts of the switches are illustrated in cross section.' l rlhe motor generator set comprises a driving motor 11, illustrated for convenience ot description as of the directcurrent type, and a variable voltage direct current generator 12. The armature ot the driving motor is'designated 13 and its field Winding 14. .The ar mature ot' the generator is designated 15, its series field Winding 16, and its separately eX- cited iield Winding 17. The elevator motor is designated as a Wholeby the numeral 20,'its

armature being designated 21 andkits heldA Winding 22. An adjustable iesistanceL/fi is arranged in shunt to the generator vseries field I Winding.- Discharge resistance 2l is` provided :torthe generator separately excited tleld Winding While discharge resistance 2G is Y provided for the elevator; motor lield winding 22. A resistance 27 is providedfor controlling the. strength of the generator field and therellore the vvoltage appliedfto the elevator motorl armature during car switch operation. .v Another resistance 28 vis provided for controlling the strength of the generatortieldduring thel Cil leveling operation. is a resistance employed for forcing a rapid reduction in the strength of the generator field upon the initiation of the leveling operation to continue the motion of the car to the landing in case of an underrun. 19 is the up field strengthening resistance and 39 is the down field strengthening resistance. A resistance 29 controls the strength of the elevator motor field during different conditions of operation. 30 is the release coil for the elevator motor electromagnetic brake. This coil is provided with

discharge resistances

31, 32 and 33 for controlling the application of the brake under different conditions of operation. 34 and A35 are the up slow speed contacts and the down slow speed contacts respectively of the leveling switch, the leveling switch up and down fast speed contacts being designated 3G and 37 respectively. 38 is the armature and 40 is the field winding of the motor 41 for moving the rollers of the leveling switch inte position to clear the leveling cams. 42 is the armature and 43 is the field winding of the door control motor 44. 45 and 46 are the direct current supply mains. 47 is a double pole knife switch for ,connecting the system to the supply mains.

In order to suit the type of diagram employed, the blades of this switch are shown separated. The car switch is designated as a whole by the numeral 43. 50 is the safety switch in the car. The series of door contacts are indicated by a single set of contacts 51. The gate contacts are indicated as 52. The various safety, limit, stop and emergency switches are omitted in order to simplify the description.

The electromagnetic switches have been designated as follows:

A-potential switch,

B-up main direction switch,

C-down main direction switch,

D-first accelerating switch,

E-second accelerating switch,

li`-se1ies field switch,

G-series field relay,

H-main brake and field switch,

J-door control motor switch,

K-door control motor maintaining relay,

l\f-maintaining relay,

N-scquence relay,

(AL-accelerating relay,

Phard brake switch,

R-retaining switch,

S-slow down switch,

LB-up leveling direction switch,

LChdoWn leveling direction switch,

11H-leveling brake and field switch,

LF-fast speed leveling relay,

SB-up field strengthening control switch,

SCd0wn field strengthening control switch.

Throughout the description which follows, these letters, in addition to the usual reference numerals, will be applied to the parts of the above enlinieratcd switches. For example, contacts llil are cont-acts on the up main direction switch, while actuating coil A533 is the coil that operates the potential switch. The electromagnetic switches are shown in their decnergized positions. Reactanccs are similarly designated by the character X.

Upon the closing of the knife switch 47, the driving motor 11, elevator motor field winding 22 and potential switch actuating coil A53 are energized, the circuit for coil A53 being through safety switch 50. ylhe driving motor starts in operation, bringing the generator 12 up to full speed. The series field winding and starting means for the driving motor are omitted to simplify the description. With the elevator motor at rest, the current supplied to its field winding 22 is reduced by section 54 of resistance 29, providing what may be termed a standing field, The circuit for the elevator motor field winding may be traced from the lefthand blade of switch 47, line 55, by way of line 56 through field winding 22, resistance sect-ion 54 and second accelerating switch contacts E57, line 58, to the right-hand blade of switch 47. It is not desired to apply 'full line voltage to the field winding 22 when the elevator motor is not in operation because of increased power consumption. On the other hand, it is not desired to have this field winding' deenerg'ized with the elevator motor at rest as a mattei' of safety and because of the time constant involved in building up. The potential switch, upon operation, causes the engagement of contacts A60 and AG1., preparing the circuit for the generator separately excited field winding, the electromagnetic brake release coil and the control circuits. 'he condition of the circuits so far described might be termed normal.

Referring briefly to Figure 2 the car switch 48 comprises a set of up contacts 62, G3, 64, G5 and G6 and a set of

down contacts

67, 68, 69, and 71. A contact segment 72 for bridging the contacts of each set is mountcd on the segmental support 73 of insulatingl material. A cam 74 formed on the suppint above the pivot point 75. The cam is formed with a centrally disposed depression 7 G into which the operating roller 77 of the gate and door switch 7S extends with the car switch in neutral or oli' position. The switch 75; is pivoted at 30 so that movement of the car lswitch in either directioncauscs the engagement of the switch contacts. rlhe car switch is operated by means of a control handle Si. It is preferred to provide centering springs (not shown) on the car switch to cause it to be returned to oit' position when released by the operator.

Referring back to Figurev 1, assume that the system is designed for an installation of several floors and that the car is at rest at the :first floor with the gate and door open.

llt)

lli

CnA

In the starting` operation,ftheV operator first gives the car switch a vvslight' initial move'-v inent to effect the closure of the gate and door `switch 78. VFor convenienceof description,

this switch is arranged to complete a cir# 1 cuit vfor the door` control motor switch actuating coil J 82. This circuit may he traced from the lett-h and jbladeof switch 47, by way o'l: line 55 through contacts A60, by way of 'line 83 through rcoil 582, resistance 84 and switch 78, linev85, switch 50, line 8G, line` 58, to the Vright-hand blade of switch 47. The door controlmotor switch, upon operation, causes the engagement ot contacts (T87,

completing the; circuit- 'for the door control l motor 44. This circuit may betraced from the left-hand hlade of switch 47, by way ol line through contacts A00., hywa'y of line f 88 through contacts 187,v door controllmotor field winding 48 and armature 42, by way of line 58 thi'oiighicontacts v111151,@ the rightvhand blade ot s i'itcli 47. i

Referring again to .Figure 2, motor 44 op- Leiates pneumatic `gate and door operating A mechanism, as tor exampleV through linkage `90` to move ygate yclosed positionand to withdraw the revalve 91 for gate engine'92l to tiriim;` camv 93 from engagement with the roller provided on the endet the door engine valve lever 94. The lever 94 is operated by a spring to move valve 95 `for the door engine 96 to door closed position'. rEhe gate and door engilles operate throughmechanism not shown tojclosefthe car gate99 and hatchway door v 109. 1t is to be understood that a door is provided in the hatchway at each landing.

Referring back to Figure 1, itA the'operator,

after he has closed the' gate and'door, desires to open them, or if. hey desires to arrest their movement, he may do soby releasing the car switch to .return to oil position. This causes the opening of the gate and door switch 78 with the consequent deenergization of coil d 82 and the separation of contacts 587i 1n this manner, the circuit for the motor 44 is broken. rlfhe spring 97, shown in Figure 2,

operates upon the deenergization of motor 44 to niovevalve 91 and, through cam 93 and lever 9:4,.valve 95 into positionsto cause the reverse operations of the engines 92r and 96 to openthe gate and door. Obviously other `torii'isot poweroperated gate and door inechanisiiis, such aselectric in' lieu of pneumatic,

maybe employed without departing from the' y spi rit ot th ev present invention.

, Assuming .that the gate doors Va re closed, the gate contacts 52 and door contacts Y may Y now move the car switch to full operated'porsitioii to startfthe car in the upV 51 are in engagement. rthe operator direction.

t is to be noted that the gate and door switch 78 remains in Aclosed position so long as t ie car switch is moved out ofitiieutral77 position. Upon the engagement of contact segment 7 2 and Contact 64, circuits are simultaneously completed Jfor the oppositely wound coils N98 :and .N100 ot the sequence relay, actuating coils H101 or" the-main brakeaiid field switch and B102o1y ythe up mainV direction switch being in the circuit orcoillllOO. The en s gagement oi" the contact segment and contacts '65 andv (l'pie'pares circuits for the actuating coils of the accelerating switches.'

The circuit for, coil N98 ot `the sequence relay may he traced from the leiitfliand blade ot switch. 47, by way of line through 'contacts A60, by way of line 108 through coil 1198 and .resistance 104contacts 62 and'04 ot the car` switch, by way of' line 105 through contactsl C100 o the down main direction switch, line 85, to the right-hand blade of switch 47 .as

aoove traced. The circuit 'for coil N 100 mayv be traced from the left-hand blade ot switch 47, by wa i of line 55' through contacts A60,

kby way oi' line 107-through door contacts 51,

gate contacts 52, sequence relay contacts N108, and coils N100, H101 and B102, contacts 63 andv64 of the car switch, to the iightf hand blade of switch 47 as above traced. The

purpose of the sequence relay N is to insure the closure of thegate and doors be'lore startling the car. Coils N98 and N100, beine dii'- .switch segment 72 'engages contacts 04, coil N98 alone is energized, resultingin the separation oi contacts N108. The separation o1c contacts N108 prevents the energizatien oi coilN100, maintaining the sequence relay operated, and of coil B102, preventing` the operation of the up main direction switch te leilect the starting of the cai'. 'The gate and door switch 78, therefore, is closed bythe initial ii'iovenrient of the car switch so that the `gate and Ydoor contacts may be closed before the engagement of segment 72 and contact 04. However, it the car switch is moved into position where segment 72 engagescontact 04 oe-v iiore the closure of the door and gate contacts,

fthe sequence relay operates to prevent the starting of the cai'. Thus it is impossible to start the car on the door or gato contacts.

Assuming that the sequence relay has op` erated, in order tofstart the car the car switch is' returned to a position with segment 72 disengaged -lrorii contact 04. deenergizingcoil N98 to permit contacts N108 to reengage.

1t the gate anddoor are closed, the car switch may be returned immediately to iull on posi tion. Otherwise, closing oic the gate and door must be effected 'before the car switchl is moved into Vfull on position.

1t is preferred to provide the tion .switches with aA mechanical" interlock main direcing to prevent their simultaneous operation. Such an interlock may be of the torni ot a 'alking beam pivotally mounted for engagcatches on the armatures ot these switches. Upon operation ofthe up main dif rection switch in response to the energize,- tion oil its actuating coil B102, contacts B110 separate and contacts B109, B111, B112 and B113 engage. rEhe separation ot contacts B110 breaks the circuit leading trom the car switch down t'eed Contact 69, contacts B110 and the corresponding down direction switch contacts C106 serving as electrical intel-locks as is well understood in the art. Contacts B109 will be rcteri'ed to later. The engagement ot contacts B113 prepares the circuit: for the up main direction switch holding` coil B115 and the main brake and field switch holding coil H110. The engagement o1'I contacts B111 and B112 completes a circuit ilor the generator tiel d winding 17. This circuit may be traced trom the lett-hand blade of' switch 4J, by way oit' line 55 through contacts A00, resistance 27 and contacts B111, by way of line 117 through ticld winding' 17. by way ot line 58 through contacts B112 and contacts A61, `to the right-hand blade oit switch 17.

The main brake and field switch H operates simultaneously with the main direction switch B. Switch lil, upon operation, causes the separation oit contacts H119, H122 and H123 and the engagement ot contacts H1251-, H125, H126 and H127. The separation ot contacts H119 disconnects the generator lield windingl from the generator armature. The purpose ot this arrangement will. be expl ained later. Contacts H122 "are in the circuit for the resistances employed to control the generator iield strength during leveling. The purpose of these contacts also will be eplained later. The separation ot contacts H123 disconnects resistance 33 trom across the brake release coil 30. Resistance being ot' low ohmic Value, its disconnection be'tore contacts H124 engage prevents excess power consumption trom mains and 4G. The engagement ot contacts H127 establishes a circuit Afor the door control motor maiutainingl relay actuating coil K130. This circuit may be traced from the lett-hand blade ot switch 17, by vway ot line through contacts A00. b v way ot line Si?) through coil .132, b v way ot line 1211 through up le 'cling direction switch contacts 1113132. down leveling direction switch contacts 11(3133. contacts H127- aud coil X130, line 85.. to the right-hand blade of' switch 41:7 as previously traced. The engagement of contacts lL 125 turther prepares the circuits for the actuating coils of the accelerating switches. The engagement oit contacts H126 short-circuits section 5% ot the elevator' motor tield resistance 29, permitting the motor tield to build up to its 'full strength. The engagement oit contacts H1242. completes the circuit for the brake release coil 3 This circuit may be traced from the lett-hand blade of switch t?, by way ol line through contacts A60, by way vot line 131 through contacts 135 operated by the brake` b 'alte release coil 30, retaining switch actuating coil R128 and contacts H124, by way ot line 58 through contacts A01, to the right-hand blade ot' switch 117.

The door control motor maintaining relay coil K13() in the circuit above traced is suhjcct to the potential drop across resistance Sil. The system is arranged so that the voltage thus applied to coil X130 is sutlicient t0 etlect the operation o'lf the relay. Contacts X136 engage, upon the operation of the relay, to by-pass contacts H127. The purpose of this arrangement will be seen from later description. The operation of the retaining switch B in response to the energization of its actuatingcoil causes the engagement of contacts B250, 'to complete the circuit for the down tield strengthening control switch actuating coil S0251, the circuit having been prepared by the previous engagement of up direction switch contacts B109. This circuit may be traced trom the lett-hand blade of switch 117, by way of line 55 through contacts A60, by way ot line 252 through coil S0251 and contactsB109, by way of line 253 through contacts R250, by way of line 58 through contacts AG1, to the right-hand blade ot switch 47. The down lieldstrengthening control switch, upon operation, causes the engagement of contacts SC254 and SC2-55. The engagement ot contacts SC255 prepares the circuit ttor down field strengthening' resistance 39. Contacts SC254 by-pass contacts B109 so as to maintain coil SC251 energized until contacts R250 separate. rlhe purpose of this arrangcnient also will be seen from later description.

rEhe brake release coil 30 being energized, the elevator motor lield being connected directly to the mains 415 and A10 and current being` supplied from the generator armature 15 to the elevator motor armature 21, due to the energization ot the generator separately excited ield winding, the elevator motor starts.

As the brake releases, the brake switch contacts 135 sepa-rate to insert cooling resistance 137 in series with the brake release, coil. These brake switch contacts are preferably arranged to be separated at the end of thc releasing operation. Separation of contacts 135 also breaks the short circuit around coil @138, permitting the operation ot the ac celerating relay O. rllhis relay operates to cause the engagement of contacts 0140, completing the circuit for the first accelerating switch actuating coil D141. The purpose ot this arrangement is to utilize the time constant ot the brake tor timing the acceleration et the motor, more speciticall' t'or timiner the operation oit? the. .tiret accelerating switch.

- operating rollers so as to clear the leveling switch,to the right-hand blade eration will befexplained later.-

Although the brake release coil isnenergized `at thesame time that powervis-suppliedto the motor, the brake shoes do not liftzat once because of the inherent time constanty ofthe vbrake magnet and because thezbralreshoes and lever' arms represent considerable mass to be setin motion. The circuit for coil D141 completed by contacts O140may be traced` trointhe lett-hand bladeof switch 47 ,by way of'line 55 through contacts A60, by' way et' line 107 through thedoor contacts 51,-gate.

contacts 52 and contacts N108, by way of `line 142 through contacts H125, contacts 0140 and coil D141, contacts 65and 6401iv the car as previously traced.

The operation cik they irst accelerating switch, in response to the energization of its actuating coil, causes the' engagement of contacts D143, D144, D145 and D146." rThe en i gagement ot contacts D143 completes the circuit tor the lleveling switch motor 41. This circuit may beY traced from theplett-hand bladeof switch 47, by wayof line 55 through coiitactsA60, by way ,of line 147 through contacts D143, field winding and armature 38 o1 motor 41, bylway oi lineV 58 through contacts A61, tothe righthand blade of yswitch y cuit may be tracedv from the left-hand blade of switch'47,"byfway of line 55 through contacts A60, by wav of line 148 through coil H116 and contacts D144, byway of line'150 through coilB115 and contacts B113, line 151,

line 85, to the right-haiid` blade of switch 4 7 `as previouslytraced.v kThe purposeof the' energination o1l these holding' coils willV be seen ti'oinv later description` The engage-y nient otcontacts D146 completes thecircuitk 'lorthe secondl accelerating switch actuating coil E152. This circuit may be tracedv from the legit-hand blade of switch 47 by way oi:VV

line 55 through contacts A60 by way et line 107 through door `contacts .51,gate contacts and contacts N108, :by wayot line L142 through contacts H125, by way ot'line 153V through contactsD146, reactance 1X154 andl coil E152,

Vcar switchcontacts

66 and 64,`toy

lthe right-hand vblade of switch 47 as previouslv traced. TheV engagement voi contacts D145 creasing' the voltageapplied to the-generator field winding. {Thus'the generator' E. M F. is increased, increasing the speed of the motor.v -l f The second acceleratingswitch E does not operate immediately tl of switch 47 the circuit orits actuating coil is completed, its action beingl de -A layed .by the edectzof reactance X154. Upon operation, contacts E156 and E57 separateand contacts E157 and E158 engage. The separation `ot' contactsk E156 removes the shunt circuit around a portion of resistance 160. Theseparation ofcontacts E156 before contacts E158 engage prevents excess` power consumptionfrom mains and 46. The engagement of contacts E158 completes the eircuit for the rst accelerating switch holding coil, D161 and the maintaining relay lactuating vcoil M162. -Thiscircuit may be traced from the lett-hand blade of switch 47, by way of lineV through' contacts A60,vby way ofline 151 through contacts E158, reactance X163, coil D161 and coil M162, line 85, to the right-hand blade ol:l switch 47 as previously traced. The maintaining' relay contacts M164 are thus closed to by-pass contacts D144. The

purpose of this arrangement will be described later. lThe engagement of contacts E157 short circuits section 165 ofresistance 27 to increase the voltage applied to the generator separately excited lield winding'. The E. M. F. ofthe generator, therefore, increases toits i'ull value andthe speed of the elevator motor increases. The sepa-ration of contacts E57 removes .the short lcircuit'pfor section 167 ofY resistance'29in the elevator motor field winding circuit, bringing the elevator motor up to full speed. Y

. The starting of the carjin the down direction is accomplished in a similar manner and will be only briefly described. The operator` iirst moves the cai' switch into position tol cause the closure of the ygate andr door and then into full on position where its contact segment 72

bridges contacts

67, 68, 69, 70aiid 71. vThus the circuit is completed for. the down main direction switch actuating coil C168.' This circuit may be traced from rthe lett-hand yblade of switch 47, through coilr H101 as previously traced, by wayof line 170` through coil'ClGS,

car switch contacts

66 and 69, by way of line 171`through contacts 13110,.

line 85, tothe right-hand Vblade of switch 47` as previously traced. The circuit for coil N98 isby way of line 172. The circuit orcoil `D141 isbyl way of line`173. The circuit for coil E152 is by way of line 17 4.V The'down main directionswitcli,upon operation, causes the separation of contacts C106 andtheengageinent of .contactsC169, C17 5, C176 and C177, these contacts corresponding with up Vmain direction switch contacts B110, B109, B111, `B112 and B113 respectively. Contacts p Y l AC169 prepare a circuit for the upflield strengthshort-circuits section 155.01 resistance 27, in-

ening control switch Aactuated coils S1317@ to be. completed by contacts R250. The hold? soy lio

tion is the same as described for starting it in l the up direction.'-

Assume that the car is running-in the up direction and that'the operator centers the car switch between the second and third floors in order to stop at the third floor landing. rIhus the contact seginent 72 inoves oit

contacts

66, 65, G4: and G3 and the circuits 'for the second accelerating switch actuating coil E152, iirst accelerating switch actuating coil D141, n'iain brake and tield switch actuating coil. H101, up niain direction switch actuating coil 13102 and sequence relaycoils N98 and N 100 are broken. rlhe second accelerating switch drops rout immediately. The iirst accelerating switch, niain brake and iield switch and up inain direction switch are niaintained operated, however, by holding coils D161` H110 and B115 respectively. The decnergization of coils NQS and N100 is in preparation :tor the next starting operation. t is to be noted that switch 7S is opened by the centering ot the car switch. rilhe circuit for coil JSE, however, is maintained t irough contacts H127 and K12-l0 in parallel and coil X130.

The second accelerating switch, upon drop ping` out, causes the separation of contacts E157 and E158 and the reengagcinent of con tacts E57 and E156. The separation ot contacts E157 reinserts section 165 ot' resistance 27 in series with the generator separately en cited field winding` to decrease the E. M. F. oit the generator. rlhe.engagement of contacts E57 short-circuits section 167 of resistance 29, increasing the strength or" the elevator lnotor field for the stopping operation. lith the generator E. M. E. loweredA and the strength ot' the elevator inotor iield increased, the speed oi" the elevator inotor is decreased. The separation of contacts E158 breaks the circuit for l'ioldiirg` coil D161 and willi/1162. rllhe iirst accelerating switch D and maintaining relay M do not drop out immediately, however, their action being delayed by the eilect et reactance X168 in series with the coils and the discharge resistance 100 in parallel with the reactancc and the coils.. rlhe engagen'ient ot contacts E150 to short-circuit a portion of reffist.ince'100 is el'l'ective to prolong the tinie element of the switch and relay. The tiinc element inay be adjusted to the desired value.

b v changing tl' e ainount of the resistance por tion shortcireuited. Relay M is preterably adjusted Vto hold in at a sinaller current value than the accelerating switch D. This may be readily accomplished due to the tact that the relay is much `smaller and therefore lighter in construction than the accelerating switch movement of the car switch as above dcseribed. The separation oit contacts D145 1e nieves the short circuit for section 155 ot' resistance 27, decreasing the strength of the generator field. Thus the generator E. l il. E. is again decreased and the speed ot the clevator motor is reduced.

The separation of contacts D 143 deenergizes the leveling switch niotor al1. 1n this inanner the operating rollers et the leveling switch are extended Jtor engagement by the levelingearns. Referring briefly to liigure f2, the leveling switch inotor is operatively connected to the leveling switch by means et an arin 180 on the inotor shaft, a connecting link 81 and a lever 182. 1n thel starting operation, the niotor l1 beingenergized, aria 180 rotates, acting' through lint; 181 and lever 1532 to inove the leveling switch as a whole about a pivot. ln this inanner the leveling switch operating rollers 183 and 18d are inovcd into position where they do not engage the leveling earns 185 and 180 duringinotion ot the car, a stop being provided lto determine the extent ot the inovcinent. ltis to be understood that leveling cains are prorided for cach tloor. rlhe leveling switch is pivoted on a bracket 18T secured to the car iframe. ln the stopping operation, upon the decnergization oit the leveling' switch inotor, a spring (not shown) nieves the lever 182 and therefore the leveling switch bacl'into the tirst described position with the rollers 133 and 131 extended for engagement by the leveling cains. Each pair of leveling

switch contacts

341, 35, 3G and 37 comprises a stationary contact and a inovable contact operated by the engagement of its corresponding roller and leveling cani. The fast speed contacts 3 and 37 are arranged to separate before their corresponding slow speed contacts 131'- and 35 in the leveling operation. Spi-in (not shown) are provided for causing the separation ot the contacts oi 'the pairs asthe leveling operation is effected and stops are provided for determining the eii'ent oi niovenient ot' the rollers as they7 ride oli the leveling cams.

lt will be assinned that the car has not reached the landinfr and that the up lcveling switch operating roller 18? nieves onto the vertical surface of up leveling cani 185 before relay lil drops out. T he engijagenient ot' leveling switch up slow speed contacts il@ completes a. circuit for the. up levelingdirection switch actuating coil lillltltl and the leveling brake and eld switch actuating coil 1111.190. rlhis circuit niay be traced 'from the left-hand blade oit switch L17, by way of line through contacts A60, line 191, leveling switch contacts 3ft, by way et line 192 thro u gli coil Ll3188 and coil LlliQO, line 85, to the rightshand blaue ot switch el? as previously traced. rllhe enigagcnent of the leveling switch up 'last speed contacts 36 completes tuating. coil LF193. rrIhis vcircuit inay be- `traced from the left-hand blade 'of switch 85 through coil LF193, to the right-hand the circuit tor 'fast speed leveling relay ac- ^line 191, levelinf switch contacts 84, line 1911,

leveling switch contacts 36, by yWay offline blade o'sWitch 17 as previously traced. It is V t be noted that, due to the lact'that thel cir cuit for coilLl `-193 is through leveling switch slow speedcontacts 34, thecircuttor coils 41318?) and LH190 must be madein order that thecircuit tor coil LF193 may be completed. The up levelingv direction switch LB, upon operation, causes the separationyot'contacts lil132 and the engagement of cont-acts LB19, 1115196, LB197andLl3199. The engagement ol contactsl LB199 has no particular effect at this time. Contacts 1113132 will be referred tov later; The engagement of con--V tacts LB195 and 1115196 prepares a circuit 1for portion 18 ot the generatorjseparately excited field Winding. The' engagement of contacts e LBLQ completes the circuit for up series eld relay actuating coil G1931 and uphardbrake switch actuating coil P200. rlliis circuit may be traced from the left-hand blade ot switch 47, by Wayofline 55 throughcoiitacts A60, by Way of line 2,01'through contacts 1113197, coil G1298, coil P200, and portion 202 ot revactance X203, line 20st, by Way of line`v 58 Ahrough contacts A61, to the right-hand blade otrswitcli 17. 1 y The levelingl brake and field tacts lil-1205, LH206 andLH210 and the en-' gagement ot contacts LH207 and 11171208. eiect as they are bypassed by Vcontacts Contacts LH205 are in the circuit for resistf ance 33 across the brake release coil., Contacts 11H20@ are in series with contacts H119 contacts Hltin'the circuit for the brake release coil.- Contacts ljl208 ley-pass contacts ,H126 in, the circuit torsection ol the ino# tor held resistance 29.- T he purpose olf 4contracts 1111205, 11191200, LEY/307 and 1111208 will be seen as thedescr-iq)'tion proceeds,vv vContacts 11H21() break the shunt circuit comprising` f resistance 160 for coils D161 and M162.

The fast speed leveling relay, uponvoper ation, causes the engagement ot.V contacts LF212,LF213 and LF2111. The engagement of contacts LF213 short-circuits a portion et resistance 28, the purposevoy Wliicli'a'rill lbe seen as the descriptionproceeds.` 'llh'een'- gagenient oft contacts-1152121:by-passes con" `tacts 1413132, 110133,1{127 and 1G36, coil X180 'and switchTS through resistance in a circuit for coil 1820i the door cont-rol inotorswitch; Sincel the engagement of con#y tacts LF21tfgenerally occurs substantially simultaneously with the` separation of con- ,e switch e?.

switch, op eratingl simultaneously with the up 4levelingl tacts 103132, the switch kJ does not drop out.

Even if switch J should drop out, the-iinniediate reenergization ofcoil J82 upon the engagement of contacts 1113214, would prevent'the operation ot the gate and door operating mechanism dueto the time requiret for theinechanisni t'o'stai't in operation. The

circuit for the'slowlo'wn switch actuating' coil S215. rThis circuit may be traced 'from the lett-hand blade ot switch 4'?, by Way ol" line through contacts E160, by Way of line 211 through contacts LF212, coil S215 and reactance X216, by Way of line 58 through contacts A61, to the right-hand blade of rEhe slow-down switch S, upon operation, causes the separation ol: controts S217. to remove the short circuit for resistance 2o.

The separation ot contactslal4l210 to breal the circuit torresistance 160 as above set forth causes relay M to drop out and sep-lk S0254 vto maintain the energization `tor the down ipield strengthening cont-rol switch actuating coil SC2? 1. The separation of. contactsllll and B112 breaks the circuit tor the `generator field Winding 17. However,

The-purpose of this arrangement `Will be seen troin'later description. y f

l circuit for the doorcontrol motor m intaini portion 1S of the .iiold Winding' is simulta-`- neously connected to onset the liues'and neutral by contacts H1 of the main brake vand yfield switches set tort-h below. lit is to be noted that the' source ot supply illustrated is direct current and it is preferred that it bea three wire system' hat o; the neutral grounded. rlihe neutral is Vini; ated by the reterence'character 201; ln the event llt) only alternatingv current is available, it is to i be understood that al three Wire e er driven by an alternatino,` current niet be employed to,supplythe-lield wiiidinss and the rcontrol*circuitsV The switch l-Lupon dropping out, causes the separation of contactsil'l1211, H125,H126 and H127 and the engagement of contacts H119, `tl122 and H123. rlhe separation 'of contactsl and H127 isrin preparation for .the next starting' operation. The separation or contacts H123.; and H126 Vis 'Without effect, the circuit for the brake `release 'coil 30 being,` maintained rec@ Cil

by contacts LH207 and section 54 of resistance 29 remaining short-circuited by contacts LHUS. The engagement of contacts H119 and H123 also is Without etliect as the circuit for reconnecting the generator separately excited lield Winding to the generator armature is maintained broken by contacts 1111206 and the shuntl circuit l'or the brake release coil 30 comprising resistance 33 is inaintained broken by contact-.s` Lili-O5. lhe engagement of contacts H122, however, completes the circuit itc-r portion 18 oi the geiierator lield winding. Yl`his circuit may be traced Ytroni the left-hand blade et switch 17, by VWay of line 55 through contacts not), by n'ay of line 25S through contacts Lli`213, the remaining portion o'l' resistance 22 and contacts H122, by way of line 25T thi-ouch contacts 1115195, line 258, portion 18 oit lieid winding 17, line 260, back to line 256, through contacts LBlQG, to nent-ral 261. lith contacts LF 213 in engagement, short-circuiting a portion of resistance 2S and with portion 1S ol the generator lield winding connected. to the mains, an E. M. ld. is generated which causes the elevator inotor to run at a suitable tast leveling speed. Discharge resistance 211 acts not only to smooth outthe changes in generator E. M. l". due to the reinsertion of resistance 2T in circuit with the separately excited ield Winding in steps but also acts to prevent a sudden drop in value of the E. M. F. upon the changing over of the connections :tor the separately excited lield Winding. It is to be understood that resistance 27 niay be controlled in any ninnber ol steps, two being shown merely tor convenience oi description.

Relay and switch l) do not operate iininedh ely their actuating coils are energized, their action bein delayed by rcactance X203. Snitch l), however, is adjusted to operate alinost immediately and, upon operatitm, causes the separation oi1 contacts 1722i, discoinicctiiui resistance l2 from across the braiie release coil 3l). Relay (l, upon operation,

causes the engagement oit contacts conn,

plcting the circuit tor the series lield switch. actuating coil F223. This circuit niay be traced troni the lett-han d blade ot switch el?, by way ol line through contacts AGO, by way ot line 22-1; through contactsl (i222 and coil F223, by Way otl line l58 thr eh contacts 11H19() is thusl broken.

operation so as to aid in bringing the motor to a stop. rl`he short delay in the action el" relay G, and therefore switch l?, upon the initiation of the leveling operation, is desirable in order that the current in the generator arinature-elevator inotor armature circuit inay adjust itselt' to such a value that proper series field strength during the leveling operation inay be obtained.

fis the car .nears the third floor landing, roller 183 rides oil' the Avertical surtace onto the oblique sui-tace oi cani 'lhis results in the separatiiin ot leveling' switch up tast speed contacts 25%, deenergixing tast speed leveling relay coil liliitl. ltela'if' lili, upon. dropping out9 causes the sifinzration of contacts Lli`212, Lll`2l and Lli`21-l. The separation oi" contacts lill`2lZ- removes the short circuit for the portion o'l resistance and for resistance 25. rlhe separation of contacts LF212 breal'zs the circuit for the slow-down switch actuating coil The switch S dois not drop out immediately, however, being delayed by the action of reactance X216 and discharge resistance its will be explained later, by this arrangement the generator E. M. F. is so controlled as to cause the speed ot the elevator niotor to be reduced to a value from which an accurate stop may be inade.` r1he separation ot contacts lili-i breaks the circuit 'for the door control motor switch coil i182. Switch d, upon dropping out, causes the separation of contacts 181' to denergize the motor dal, thus etlecting the automaticv gate and door opening operation. rthe gate and door operating inechanisni functions in the saine manner as described i'er opening the gate and door in response to centering the car switch. ln this manner .the automatic gate and door opening operation is tinied so that the gate and door open as the car stops at the landing. lt is to be noted, however, that the automatic gate and door opening operation cannot take place until the leveling switch 'fast speed contacts separate. Shortly betere the car reaches the exact level with the landing, the roller 1253 rides oli' the oblique .surface of

cani

1,85, thereby separating the leveling switch up low speed contactsl I'l-l. The circuit ior coils LllSS and Switch lil-'l drops out, causing the separation of contacts LH2OT and lilll and the reengagifeinent of contacts 1111295, lll-1205 and lil-1210. rllhe engagement ot contacts 11H21() is in preparation for the next starting operation. Vlfhc separation ot contacts lil-1207 breaks the circuit for the brake release coil 30, elteeting the application of the brake. rlhe separation of contacts 12H20? also breaks the circuit for the accelerating relay coil 0138 and the retaining switch coil R128. The accelerating relay O drops ont, separating contacts Olelll in preparation"for the next starting operation. The action of the retaining switch Will lill) ioV beexplained later.,` -Theseparation of contacts LH208 reinserts sectionll of resistance 29 in series with the elevator motor field winding, reducing the eurrentthereinto a standing field value.4 The reengagement of contacts LH206reconnects the v generatorv `separately' eXcited field winding to the gen-1 erator armature. The polarity of this connection is such that the generator sends current through the field winding in such manner as toV oppose the flux which lproduces the generatorE, M. F., thus tending to de'stroy the residual flux of the generator field.

Up leveling direction switch LB, dropping out simultaneously with switch LH, causes 'the separation of contacts LB195, LB196,

LB197 `and LB199 and-the engagement'of Vcontacts LB132.

LB196 disconnects portion 18`of the generator separately excited field winding from theniains, the windmg being simultaneously connected to the generator' armature bycontacts LH206 as set forth above. The separation of contacts LB197 breaks'the circuit for coils @198 and P200. The relay Gdrops out .immediately butthe dropping out of switch Pis delayed slightly due-to the effect ofthe reactance X203'and discharge resistance 226. It is to he notedthat the discharge current for up coil P200 and the reactance passes through down coil P227 in such direction as to cause coil yP22to assist coil P200 in maintaining switch P in operated condition... Relay Gr,

,upon droppingfoua causes the separation of contactsG222 to deenergize coil F223, switch 4 F drOppingout in turnto cause the engage-v 4o ment ofcontacts F225. The engagement of contacts F 225 reconnects Yresistance 23 in parallel with the generator series fieldk winding 16. Switch P, upon' dropping out, causes the engagement lof contacts P221.

Y Thus the brake being applied and the genv erator separately `excited field winding ybeing disconnected from the mains, Vvthe car is brought to rest level with the third floor landf ing. j Since 'theengagenie'nt of contacts P221 is' delayed, thebrake release coil 30 dischargesv only'finto resistance 31 of relatively high ohmic value and aha`rd application of the brakeis obtained.' In this manner al positive stop-at the landing'is assured. The car may come tothe floor and the V,leveling vdirection switchiLB' open and the bra-ke4 apply before'- the slow-down switch S dropsout; lfthecarhas'not cometo the floor'when switch SQ drops out, contacts S217 engage to short-cir-y .cuitresistance 25,` assuring that the car does not stall. The operation and' purpose ofy this arrangement will be explained more in detail later. i' Y With the sequenceof operations-as above i described the .carv will be slowed downzand The separation of contacts 1113199 and the engageinent'of contacts Ll3182 is in preparatioirfor the next starting operation. The separation of contacts LB195 and stopped level with the desired landing without sacrifice of smoothness. v However, should thecar switch vbe centered with the car at a 'greater distance from the landing, the maintaining relay wouldhold in to efl'ect, through its contacts M164, the retention of the main direction switch and main brake and field switch inloperated condition. Should relay -Mldrop out before the leveling switch contacts engage, the subsequent engagement of the-leveling switch contacts vas the leveling switch roller rides onto the cam would cause the operation 'of switches LB andLl-l and relay LF to bring the car to a level with the floor. `ln the event that the car switch is centered late in the stopping operation, as for example when the'leveling switch operating roller strikes the leveling caniv upon the dropl ping out of the first accelerating switch D, the immediate separation of contacts LH210 forces the dropping out of the main direction switch and the main4 brake and field switch to` permit the immediate change of the field' winding connection'sand thus slow down the elevator motor more rapidly. In this manner the tendency forV the car to overrun the floor is reduced.

contacts 35, hywayof line229 through coilf y i LC228, by wayof line 192 'through coil lll-1190, line 85, to the right-hand blade Vofswitch 47 as Apreviously traced. Contacts lll-1205,'LH206 and LH210 are separated and contacts LH207 and Ill-1208 are engaged so that thecircuit for vresistance 33 across the `brake release coil is lorolren, the generator separately excited field windingis disconnected from the generator'armature, the brake release coil is energized and resistance lsection 511 for the elevator motor field winding is short-circuited. Contacts LH210 insure the dropping outlofvthe main direction switch. The switch LC operates to cause the separation of contacts LC133 and the engagement of contacts LC230, LC231, LC232 and LC233. The separation of contacts LC133 is without particular effect at this time. rPheswitch R is maintained in operated condition, should there he an interval that the brake release coil 80 and coil R128 are disconnected from the mains as is being assumed, by the brake release coil discharge current. rlhus coil S0251 remains energized and contacts SG255 are maintained in engagement. rlhe engagement of contacts LC230, therefore, completes the connection of down field strengthening resistance 39 to line 256. This operation serves no particular purpose so long as the car has not overrun into the fast speed leveling Zone. The engagement of contacts LC231 and LC232 connects portion 1S ot the generator separately excited field winding to one oi the mains and grounded neutral. Due to the reversal of the direction of the current through ield winding portion 1S from that during the leveling operation with the ca r approaching the floor in the up direction, the car is caused to start in the down direction. Since relay LF is not operated, contacts LF212 are separated and therefore contacts S217 are in engagement sliort-circuiting resistance and contacts LF213 are separated so that resistance 28 is included in circuit with iield winding portion 18, causing the motor to run at slow leveling speed.

The engagement et contacts LC233 completed a circuit for the down series field rclay actuating coil G234 and the down hard brake switch actuating coil P227. This circuit may be traced from the left-hand blade of switch 47, by way `of line through contacts A60, by way of line through contacts LC233, coil G2234, coil P227 and portion 236 of reaetance X203, line 204, by way of line 58 through contacts A61, to the right-hand blade of switch 47. Relay G and switch P do not operate immediately upon the engagement of contacts LC233. When approaching the floor in the up direction, the current `Howing through reactance portion 202 caused a flux to be built up in the reactance X203 in one direction. Upon the separation of contacts LB197, the currentin thereactance and coil P200 discharged into resistance 226 tending to maintain the flux built up and, as previously explained, switch P in operated condition. Upon the engagement of contacts LC233 on the overrun, the current supplied to coils (i234 and P227 must reverse the flux in the reactance, thus taking a longer time to build up to a value suiiicient to cause the operation of relay G and switch P. rlhus contactsF225, depending for their operation upon the operation of relay G, remain closed temporarily to insure that the current in the generator armature-motor armature eircuit has fallen to a low value. Since the current in the series field winding may be flowing in a direction such as to cause the generation ot an E. M. F. which is of proper polarity for operating the car in the down direction, immediate increase in the strength ot the series field might result in another overrun, i. e., an overrun in the down direction. As the car returns to the floor. it stopped by the separation ot the leveling' switch slow speed contacts in a manner similar to that described for approaching the floor in the up direction.

It the overrun is great enough to cause the engagement of the leveling switch down fast speed contacts 37 aswell as the leveling switch down slow speed contacts 35, coil LlTlQS is energized. its previously described, relay LF causes the engagement of contacts lill`2l2, LF213 and LF214. Contacts Lll`213 short-circuit the portion otl resistance 28. Contacts LF212 complete the circuit tor coil S215 causing the-operation of the slow-down switch S and the consequent separation of contacts S217, removing the shortcircuit for resistance 25. Resistance 25, however, is short-circuited by contacts LF213. Thus the elevator motor is caused to run at its tast leveling speed. The engagement oit conacts LF214 causes coil JS2 to be energized again in the event that it has become deenerg-ized. As the car moves back into the slow speed leveling Zone, relay Ll? drops out, causing the separation of contacts 1111212, LF213 and LF214. its previously described, the separation o' contacts LF214 initiates the operation ot the automatic gate and door opening mechanism; the separation of contacts LF212 breaks the circuit t'or coil S215, the slow-down switch being maintained in operated condition by Vthe action ot' reactance X216 and discharge resistance 265; and the separation of contacts LF213 removes the shortcircuit for the portion o1' resistance 26 and for resistance lt is to be noted that down {ield strengthening resistance 39 is connected in parallel with resistance 253 during this operation due to the engagement of contacts SC255 and LC230, as above set forth. By means oi this arrangement. as will be ei.;- plained later, proper slow leveling speed is obtained lor bringing the car to the floor, where it is stopped as above described. Similar operation is had in the event et an overrun with the car moi/inev in the down direction, the holding circuit ror up iield strengthening control switch coil 5513178 being established by contacts SB266 and the circuit for resistance 19 being prepared by contacts S1326?. The circuit for resistance 10 is completed by the up leveling direction switch contacts LB199.

It is to be understood that the operator may control both the acceleration and retardation of the car by moving thel car switch in steps. Should the operator suddenly move the ear switch from one position into the other, for example from up into down position, injury to the system is prevented by contacts B which remain separated until the up direction switch drops out. It is to be noted that, when the ear is stopped between Hoors, the switch P is not operated. Thus contact-s P221 are in engagement and a. soft application o the brake is obtained.

When generators, suitable Ytor supplying power to an elevator motor for high speed installations, are employed also to supply power to the motor during the leveling period as in the system above described, variations in the leveling operation are likely to occur dueto the slowness withr which vthe strength of the generator field reduces to a value suitable for obtaining the desired slow levelingspeed ofthe elevator' inotoi. sistent results may be obtained under such l conditions by forcing the generator field strength down to such a-valu'e that a slow lev- Y to a very low value and thus causes a. more rapid decrease inthe strength of the generator field.` In some installations, the value of suchV a resistance may be infinite so that vthe decrease in generator field strength is governed entirely by the action of the current *in the lield winding discharge circuit. In the control system described, this resistance has been designated 25. This resistance may be inserted in a circuit connected across mainsv and 46 and including. the wholeiiield winding. But in order to-afford protection against the o'ccurrence'of excessive speeds, as will'be pointed out later, it is preferred to employV only a portion of the field winding connected to one supply main and a grounded neutral. In accordance with jthe preferred arrangement, therefore, resistance 25 is inserted in circuit with only the portion 18 of the field winding, theinsertion being' governed by the operation of the fast speed leveling relay LF and the slow-down. switch S. In a briefri sum of the operation, as the car enters the slow speed leveling zone, the-.fastspeed leveling relayv drops out, causing the separation of contacts LF212 and LF218. The separation of contacts LF212 breaks the circuit for the slow-down switch actuating coil S215, the

slow-down switch beingmaintainedy operated by the action of reactance X216l and discharge resistance 265. y Contacts S217, there-V fore, reinainseparated'so that the separation of contacts LF213, instead of inserting only the remainder ofk resistance 28 in circuit with portion 18 of the generator yfield winding,

inserts in addition resistance 25. Were resistance 25 permitted to yremain in circuit with the field windingportion yfor too long a' period, it would cause *such ya.\reduction in the generator field strength, and therefore generator E. M. F., as might result in stalling the elevator motor regardless of whether l the car had reachedthe landing. Such va situation might result under vcertain conditions of operation as where the car is slow in coming to the floor. The stalling of the car is Conprevented,ihowever, by the action of the slowdown switch S, this switch, as above described, being maintained .in operated condition for a. certain time interval by the action of reactance X216 and discharge resistance 265. Thus the car may come to the floor and the leveling-direction switch drop out before switch S dropsout to cause the reengageinent of its contacts S217. Should the car not reach the landingwithin the tii'neinterval for switch S, however, the dropping outl of this switch and engagement of its contacts S2117 short-y circuits resistance 25, leaving onlyl resist-ance 28 inIk circuit with the generator field winding. The value of resistance 28is so chosen that the generator of an E. M. F. of sufficient kvalue to cause the continued operation of the inotor to move kthe car to a level with the landing is assured. The value of resistance 25is so chosen and the `timing of theslow-down switch is so adjusted as to give proper operation for the particular installation when the car is beingstopped as it approaches the fioor.

Upon the eiiergization of the generator field winding to `return the car to theffiooi after anv overrun, the generator field assumesl au entirely different state magnetically, due

primarily to the effect of the hysteresis of the iron and the fact that the fieldV strength being built up rather than reduced; Thus toinsert'resistance 25 in the circuit for field winding` portion l18 upon the separation 'contaets LF213 would cause too greaty a reduction in the strength of the generatorfield; resulting in the car being brought toa vpre-l mature stopbeforethe landing is reached andgtlien being started again as resistance 25 wasv sliort-circuited by the subsequent engagement oflcont-acts 'S217'. It is preferredV to overcome such' a condition'by paralleling resistance 25 by a resistance of' relatively low ohmic. Value during' the operation of returning.` the car to the `floor after an overrun.

Resistances

19 and 39, in 'conjunction with the field strengthening control switches SB and SG, the retainingv switchR 'and the leveling direction switches LB and LC are employed for this purpose. `As has previously been explained, contacts SC255 are caused to engage during up car travel and contacts SB267 during down car travel, thesev contacts being maintainedvr in engagement during an overrun by the action of the retaining switchR. Thus the engagement of contacts LC280,upon the return of the car to thefloor after. an overrun in the 'up direction, Vconnects resistance 39 in parallel with resistance 25.I and engagement of contacts LB199, ,upon

the return ofthe car tothe floor after an overrun in the down direction, connects resistance 19 in parallel with resistance 25. Upon the separation of contacts S217, therefore, the reduction in the current supplied to field winding portion A18 is only sufficient to cause a reduction in the speed ot' the elevator motor to the desired value.

lt is preferred to employ two tield strengtheninfjI resistances 19 and 239 to obtain the above described operation since each may be separately adjusted to suit `the requirements oit the particular installation. lt is to be understood, however, that only one lield strengthening resistance may be employed with two parallel circuits connected in series therewith. one parallel circuit includinge` contacts and contacts LCQSO arranged in series relation and the other including contacts S1326? and contacts 1113199 arranged in series relation.

rlhis arrangement ior the control of the strength ,oi2 the generator iield aids in guarding against the occurrence of excessive speed oiE the elevator car during' the leveling period, being particularly ei'ective to prevent such occurrence in the event of the grounding of certain parts ot thesystem. rlhe automatic opening oi the gate and door during the leveling period renders the feature ot particular in'iportance. In systems such as those employing,l resistance in series with the elevator' motor armature to control the speed of the motor during leveling, or wherein the voltage applied to the armature of the elevator motor during leveling is controlled by means ot resistancelin series with the whole of the.

separately excited iield winding of the generator, there. is always the possibility of the grounding of the whole or a part ot such resistances, causing the speed o't' the elevator motor to increase. It mechanism were employed, as in the present system, to eii'eet the automatic opening of the gate and door during the leveling period, the sudden increase in the speed might occur while the gate and door were being opened, or after the gate and door were open when the leveling arrangement is slow in bringing the car to a level with the landing. In: the present system` the possibility of occurrence ot' excessive speed 'from any cause, during` t-he leveling` period, and` therefore, .during` the opening' of the gate and door or while the gate and door are open, is minimized, with such occurrence as the result oii grounds prevented. Due to the tact that the circuit including resistance 27 for connecting` the generator' iield winding' to the source is broken by the main direction switch contacts, the accidental short-circo.itinpT ot resistance 27 during the leveling operation cannot eitect an increase in the speed of the elevator car. Also the connections for the leveling` operation must be made in order to effect the automatic `gate and door opening operation, since contacts on the leveling direction switches control the circuit for the door control motor maintainingrelay actuatingT coil H130. As previously set forth, the circuit for the field Winding portion 18,

employed during` leveling, continues to the' grounded neutral 261. Thus the maximum voltage which-can be applied to field windingportion 18 is reduced to half the value of that which can be applied to the whole iield winding during' car switch operation. Also by completing the circuit tor the field winding' portion 18 through the `@grounded neutral, the occurrence of a ground in any partof this circuit results in short-circuiting all or a part oi' the field winding portion 18, causing a decrease rather than an increase in the generator tield strength. Assuming that the circuit tor iield winding portion 18 is completed by contacts Ll3l95 and LBlQG, the occurrence oi a ground in the portion of uinding l?, illustrated as above portion 18, would have no eiiect as the circuit from the upper junction point ot windingportion 18 to ground is direct. in the case oi' the Lground ing' oit the field winding,` portion illustrated below portion 18, the tendency for an increase in total iield streng-th is compensated tor by a decrease in the i'ield strength due to portion 18. Similar protection is atl'orded in the eventthat the circuit ior iield winding portion 18 is completed by contacts LC231 and 110232.

It is preferred to employ one of the intermediate poles, as t'or example the second or third pole oit a tour pole generator, for field winding` portion 18 asillustrated. rllhe remaining portions et the field winding then serve as protectingl resistances between the grounded neutral and main 46 in the eventthat the main and levelingdirection switches are closed simultaneously. It .is to be understood that severaltypes of generatorsl may be employed and that they may be oi other numbers of poles. It is to be further understood that field winding; portion 18 may include more than one pole.

As many changes could be made in the above arrangements and many apparentlywidely ditterent embodiments oit this invention could be made without departing);k trom the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

ldlhat is claimed is:

1. In combination, an elevator car, a hoistmotor thcre'lor, a. generator for supplying current to said motor, saitL generator having a iield winding, a source ot' current, and means ttor causing` 'the motor tobrine` the car to a stop at a desired landing, said means comprising means i'or applying a reduced .'oltage trom said source to only a portion of said winding.

2. in combination, an elevator car, a hoisting motor therefor, a `c'enmatrn' for supplying current to said motor said generator having a field winding, a source of current having :i

lill

modici groundedneutral, and means for 'causing `the motor to bring the car to a stop at a desired landing, said means comprising means for connecting Vonly aportion of said-winding to one terminal of said source and said grounded y neutral. Y .l r

.3. In combination,-an elevator car,aho1st lng motor therefor, a generatorffor supplying ycurrent tosaid motor, said generator having a field winding, a multi-voltage source of current, means for applying a certain'voltage ofk vsaidsource to said field winding tolcause the motor to run at aV certainspeed, and means for applying. a. lower` voltage of said source toa portionoffsaid field winding to caus the motor to run at a' slower speed.

4. InY combination, 4an elevator car, a

' ing motor therefor, a generator for supplying current to said motor, said generator havmg a field winding, a source of current for said winding, saidy source having a grounded neutral, means for vconnecting said winding to said source, andy means for connecting a portionfof said winding toone terminal of said source and said neutral. Y i" f 5. Y In combination, an elevatorcar, a hoisting motor therefor,a generator for supplying current to said motor, said generator having afield winding, a source of current forr-l said winding, said source having a grounded winding toisaid Source to cause the motor to run at a certain speed, and means forcausing the'motor to level the car with a desired landing in stopping at a slower speed than said oertainspeed, said second named means comprising means for yconnecting a portion of said winding to one terminal of said source and said grounded neutral.

7 In-combination, an elevator car, a hoisting motor therefor, a generator for supplying currentto said motor,"said generator having a fieldwinding, a source of current having a grounded neutral, means for connecting said'winding to said sourcetocause the motor to run at a. certain speed, means for causingthe motor to level the 'carwith a desired landing in stopping atl a slower speed than said lcertain speed, said secondrv named means'comprising means Vfor disconnecting said field winding from said sourceand for connecting a portion thereof to one terminal ofy said source and'said grounded neutral, a`

hatchway door,l mechanism for causing' the hoistopening of -saiddoor, and means forinitiating the operation of said mechanism during the operation of said second 'named means..

*8; In combination, an elevator car,a' hoisting motor therefor, a generator for'supplying current to said motor,said generator having at least one field pole and a coil for :said pole, a source of current for said coil, means for causing the motor to bring the car' to: a stop at a desired landing, Said meanscomprising means for reducing the current supplied from said source to said coil to a certain value, for thereafter reducing said current. for a momentary period to a lower value and,- providing the car has not arrivedv within a certain zone with respect toV said `landing at the end of said momentary period, for increasing said current to a value greater than said lower value. v 1 ,u

9. In combination, an elevator car, a hoisting motor therefor, a generator for supplying current to said motor, said generator having at least one field poleV and a coil for said pole, a source of current, and means for causing the motor to level the car with a desired landing in stopping, regardless of whether -it underruns or overruns said landing, said last named means comprising meansfor momentarily reducing the current supplied from said source to said coil only during van underrun. g

10. In combination, an elevator car, a hoisting motor therefor, a generator for supplying current to said motor, said generator having a field winding, a source of current, and means for causing rthe motor to level the car with a desired landing in stopping, regardless of whether it underruns or overruns said landing, said means comprising means for causing current to be supplied from said source to at least a portion ofthe generatork field Winding of a value'such asto cause said motor to operate the car at fast leveling speed and as it nears the landing for reducing the value of said current to cause the motor to operate the car at slow leveling speed, and means for causing momentarily a greater reduction in the value of the current' supplied for slow leveling speedv when the car underruns than when it overruns.

11. In combination, an lelevator car, a I

hoisting motor therefor, a generator for supplying current to said motor, said generator having a held winding, and means for causing the motorto level the car with a desired landing in stopping, regardless ofwhether it underruns-or overruns said landing, said means comprising means for energizing only a portion of said winding.

12. In combination', an elevator car, 4a

hoisting motor therefor, a generator for supplying current to said motor, said generator having afield winding, means for causing the motor to level the car with a desired landing inl stopping, regardless of whether it underruns or overruns said landing, said means comprising means for energizing only a portion of said Winding', and means for reducing the energization of said winding portion during a portion of the operation of the first named means. 13. In combination, an elevator car, a hoisting motor therefor, a generator' for supplying current to said motor, said generator having a field Winding, means for causing the motor to 4level the car With a desired landing in stopping, regardless of whether it un- 'derruns or overruns said landing, said means comprising means for energizing only a portion of said Winding, and means for momentarily reducing the energization of said Winding portion during a portion of the operation of the first named means. I

14. In combination, an elevator car, a hoisting motor therefor, a generator for supplying current to said motor, said generator having a field Winding, a source of current, means for causing the motor to level the car with a desired landing in stopping, regardless of Whether it un'derruns or overruns said landing, said means comprising means for applying a reduced voltage from said source to a portion of said Winding, and means renderedk effective during the operation of the first named means for momentarily reducing the voltage applied to said Winding portion to a certain value only vduringa portion of the operation of rst named means with the car approaching the landingl in the same direction that it was traveling before the operation of the first named means.

15. In combination, an elevator car, a hoisting motor therefor, a generator for supplying current to said motor, said generator having a field Winding, a source of current having a grounded neutral, means for causing the motor to level the car with a desired landingin stopping, regardless of Whether it underruns or overruns said landing, said means comprising means for connecting only a portion of said Winding to one terminal of said source and said grounded neutral, and means for momentarily reducing the current supplied to said Winding portion to a certain value only during a portion of the operation of the first named means with the car approachingthe landing in the same direction that it was traveling prior to the operation of the first named means.

16. In combination; an elevator car; a hoisting motor therefor; a generator for supplying current to said motor, said generator having a field Winding; a source of current having a grounded neutral; a resistance; means for starting said motor, said means comprising means for connecting said field Winding to said source in circuit with said resistance and for thereafter short-eircuiting said resistance to bring the motor up to full speed; and means for bringing the car to a level With a desired landing in stopping, regardless of Whether it underruns or overruns said landing, said secondl named means comprising means for disconnecting said field Winding from said sourceand for connecting a portion of the Winding to one terminal of said source and said grounded neutral to fause the motor to run at fast leveling speed, means for reducing the current supplied to said field Winding portion to a certain value to cause said motor to run at slow leveling speed to bring the car to said landing after an overrun, and means for reducing the current supplied to said field. Winding portion momentarily to a lower value than said certain value to cause said motor to run at slow leveling speed to bring the car to the landing during an underrun.

17. In combination; an elevator ear; a hoisting motor therefor; a generator for supplying current to said motor, said generator having a field Winding; a source of current having a grounded neutral; means for starting said motor, said means comprising means for connecting said field winding to said source at a reduced voltage. and thereafter increasing the 'voltage so as to bring the motor up to full speed; and means for causing said motor to level the car with a desired landing in stopping, regardless of Whether it underruns or overruns said landing, said second named means comprising means for disconneet-ing saidl Winding from said source and for reconnecting a portion thereof to one terminal of said source and said grounded neutral to cause the motor to run at fast leveling speed, a resistance, and means for momentarily inserting said resistance in circuit with said field4 Winding portion as the car arrives at a predetermined distance from said landing.

18. In combination; an elevator car; ja hoisting motor therefor; a generator :for supplying current to said motor, said generator having a field winding; a source of current having a grounded neutral; means for starting said motor, said means comprising means for connecting said field Winding to said source at a reduced voltage and thereafter increasing the voltage so as to bring the motor up to full speed; and meansfor causing said motor to level the car with a desired landing in stopping, regardless of Whether it underruns or overruns said landing, said second named means comprising means for disconnecting said winding from said source and for reconnecting a portion thereof to one terminal of said source and said grounded neutral to cause the motor to run at fastleveling speed, a pair of resistances, and means for inserting one of said resistances and momentarily the other in circuit with said field Winding'portionto cause the motor to run at slow leveling speed during an underrun.

19. In combination; an elevator car; a

hoisting motor therefor; a generator for supplying current to said motor, said generator having a field Winding; a source of current" having a grounded neutral;means for starting said motor, said means comprising means lfor connecting said field Winding to saidy i source at a reduced voltage and thereafter underruns ory overrunssaid landing, said second named means comprising means for disconnecting said Winding'from said source and f for reconnecting a portion thereof to one ter ininal of said source and said grounded neutral to cause the motor to run at fast leveling speed, a pair of resistances, means for inserting one of said resistances and momentarily` the other inl circuit vvithv said field Winding portion to cause the motor -to run at slow leveling; speed during an underrun, and means for bypassing said other resistance to'cause the njiotor to run at substantially the 'saine slow leveling speed during the return of the car to the landing after aiioverrun as during an underrun. p Y y V 20. ln combination; an elevator car; a

hoisting motor therefor; a generator for supplying current `to said motor, said generator having' a field Winding; a source of current liaviiig a grounded neutral; meansfor starting said inotor, said means vcomprising means for connecting said i'ield winding to said source at a reduced voltage and thereafter increasing t-he voltage so as to bring the motor up to full speed; and means for causing said inotoi` to level the car with a desired landing in stopping, regardless of whether ituiiderruns or overruns said landino said'second named means comprising means for discon nectiiig said Winding from said source and .for reconnecting a portion thereof to one terminal of said source and said grounded neutral to cause the motor to run at fast level-v ing speed, a pair of resistaiices, means for iiisert-ingsaid resistances in circuit with said after the operation of said resistance insertu ing means, a second pair of resistances, and means for connecting one of said second pair of resistances in parallel With said one of the first pair of resistances to eiiiect the return of the car to the landing after an overrun in one direction and for connecting the other of said second pair of resistances in parallel With said one of. the first pair of resistances to effect the return of the carto the floor after an overrun in the other direction.

21.111 combination; an velevator Car; a

hoisting motor therefor; a generator for supplying` cuirentto said motor, said generator having a field Winding; a source of current having a grounded neutral; a resistance; means.foi-starting said motor, said means comprising means for connecting said field Winding to said source in circuit With said resistance and for thereafter short-circuiting said resistance to bring the motor up to full speed; means for bringing the car to a level With a desired landing iii stopping, regardless of Whether it underruns or overruns rsaid landing, saidsecond named means coinprising means for disconnecting said field Winding and for connecting a portion of the winding to one terminal of said source and y said grounded neutral to cause the motor to run at fast leveling speed, tWo additional resistanccs, means for causing the insertion of one of said additional resistances and the momentary insertion of the other in circuit with said portion of saidiield Winding to cause the motor to run at slow leveling speed, a fourth resistance, and means for connecting said fourth resistance in parallel with the momentarily included resistance during the slow speed leveling operation to return the car to the iioor after an overrun; a car gate; a. hatchivay door; gate and door opening mechanism; and means for causing the opera; tion of said gate and door opening mechanisin, said last named means being responsive to tlieoperation of said means for causing the motor torun at slow leveling speed.

ln testimony whereof, vwe have signed our naines to this specification.

RAYMOND A. WAITE. FRANK L. Mouais.