US1691241A - Electrical control system - Google Patents

Description

' 1,691,241 H. B. GOLDMAN ELECTRICAL CONTROL SYSTEMy Filed April 4, 1925 f3 1 Nov. 13, 1928.

Nov. 13, 1928.

. H. B. GOLDMAN ELECTRICAL CONTROL SYSTEM 3 Sheets-Sheet 2" Filed April 4. 1925 j TJ Nov. 13,- 1928. 1,691,241 .l Y H. B. GOLDMAN ELECTRICAL CONTROL SYSTEM Filed April 4, 1925 s sheets-sheet 5 abbot we.

Patented Nov. 13, 1928.

PATENT oFFice.

HARRY BENJAMIN GOLDMAN, or PITTSBURGH, PENNSYLVANIA.

f ELECTRICAL CONTROL SYSTEM.

" Application filed April 4, 1925. serial No. 20,787.

',{Myiinvention relatesbroadly to elevator i control systems, and more` particularly to electrical circuits and apparatus for increas-y ing the safety and convenience otoperation,r

ofgelevator Systems. A f

One of the objects. ot'my linvention is to provide Aa lcircuit arrangement for elevator systems operative with either an` alternating; current ora direct current sourcein which a plurality `of separate pieces of apparatus y are employed to checkone against another i the apparatus.

and cooperate in such manner thatthe elevator may be operated with a hi ghdegree ot safety at all times independent of the personal equation of the operator.y

Still another object of my. invention is to provide a circuit arrangement for elevator systems in which a plurality of protective and corrective instruments are provided through which the electrical circuits must be complet ed beforethe elevator lcan be operated up or down the elevatorshaft. e `f Still'another object of my invention is to reduce the complications of the controls in the car switch, thereby securing reliability of the operation and reduction. in the maintenance and, initial manufacturing kexpense ot Still another object of my invention kisxto provide ajcircuit arrangement which avoids the undesirable operation of reverse switches when the car is moving in either up or down direction; That iste say, Iprovide'means whereby the car must he brought to a condition of rest before operationk of the reverse switchesthereby relievingr undesirable strain i on the operating rmotor and other mechanical parts yot thersystem. n f y y vStill another object of inyinvention is to provide vasysteni wherein the same wires inystalled for operation of the elevator system `may be utilized. for the/operation of the corrective and 'piotective devices ofr my system ywithout/the requirement ofaddition al switch contacts in the car switch. l

Still another'objectof my invention is to provide non-plugging means in any elevator svstem for e preventing abusepdue 'to' inching7 that is, the tendency of thecar to stoppin a place out of level with kthe level of aiioor and 'then moved towards rthe iioorin a series of undesirable jolts, this `beingavoided .in nliy'system'by introducing' a time lag in y theopera/cien. or the circuits whereby the vator equipment comes to a positive rest before being again placed in operationgfor moving the elevator to an exact floor level.

`My invention urth'erresides in the conf struction ot timing apparatus, sequence relays, a centrifugal governor, contingent limit switch, and door contacts for connection in the elevatorcontrol circuits, as will be more fully hereinafter described. Y n

My invention provides means whereby the operator of the elevatoi` is prevented from controlling the elevator merely by operation of tlieelevator door. It is the dangerous piacticcf'oir the elevatoifoperator, when at rest adjacent Vthe tloor level, to admit passengers gto the car with the door opened and the ,car switch in On position f and then starting the car hy closing the elevator door` and completing the door contact. This is an undesirable and exceedingly dangerous method of operation. My invention provides means for eliminating this danger by requiring a series of operations where thek door contacts are first closed and then the switch lthrown 'to the On position'before the car can be made to function.

In my system the operating coilsare arranged in such relationship in the circuits Lthat contacts are' closed on the accelerating -movement and the reversemovementwith maintained at a certain tension. If these desureon7the contacts which are controlledvbyA the several armatures and giving rise to the tendency oi broken circuits Awhen 'it is necessary that the circuits be maintained. vOn

the other hand, if theicurrent through the f opening;r coils isy not reduced to a lowvalue hut is lrept fairly high then the switchesmay close whether the control resistance isintroduced or' removed from the circuit. In my system ,previde a contact ou the accelerating movement which is wired in the relay circuit, which contact must be closed in order to close the contact relay so that the current in the operating coils vcan remain constant and thus the contact A ressure may be maintained constant even though the voltage may Yary widely and the adjustment of the spring tensions on the arn'iatures may be different, thereby insuring more positive' operation of the system.

Furthermore, where it is desirable to use this protective feature with slip ring motors in A. C. s v stems. to insure the motor always starting with full rotor resistance in circuit, this protection can be secured with my circuit and not with circuits heretofore known in the art for the reason that in my system selected values of resistance proportioned to the remainder of the system are utilized. If enough resistance were sed in series with an alternating current switch to prevent the closing thereofwthe resistance being in circuit while the switch is openedmthe switch would probably fail to remain in closed position even though it might trip instantaneousl v. A. C. switches are very sensitive to changes of current so that. the insertion of a misproportioned value of resistance might result in loud humming and possible opening of the switch control circuit.

In order to obtain automatic reset of the overload relay, where one is used, from the car switch handle, it is the practice of the prior art to maire a double coil relay, one coil of heavy wire for insertion in the main circuit and the other a shunt coil for placingl across the line. The shunt coil of the ordinary overload relay is placed over the series coil and has a. resistance in series with it so adjusted that the .current through the shunt holding coil is low enough to not pull the plung f of the relay up, but will hold it there Vic series coil pulls it up into the shunt after coils magnetic circuit. if it is desired to reset the overload rela-y the circuit to the shunt coil must be broken to allow the plunger to fall into its normal position. Tn the event an overload has caused the plunger to be tripped or pulled up, thus opening the cont-rol circuit, the car switch must be returned to center in order to break the shunt coil holding circuit and release the plunger. This means usually an extra wire or wires to the car switch and extra lingers in the car switch. lith the circuit of my invention it is not necessary to have either the shunt holding coil, its resistance, any eXtra wires to the car switch, or extra lingers in the car switch. This enables me to simplify the construction of the controls,reducing their cost and increasing the reliabilit-y thereof.

I provide a. sequence relay whose twonormally open contacts in t-he control circuits break both the Up and Down reverse switch circuits, thus assuring` that no combination of shorts and grounds in the reverse switch circuits will cause the reverse switches to remain closed if the sequence relay opens. It will be noted that the sequence relays employed in my invention are wired so as to use the same conductors as arealready provided for the reverse switch circuits so that the circuits function for two purposes, that is, in energizing the reverse switch circuits and in obtaining the sequence operation.

rHeretofore in the art considerable abuse has been given to the elevator equipment due t0 reversing the mechanism before it has come to a stop and due to the sudden starting and stopping the equipment successively in inching7 to a floor level. In prior systems if the car were going up to a floor and the operator stopped below the floor, say ten inches, considerable strain on the elevator mechanism has been necessary in successively applying the operating current in the control circuits for moving the car through a series of infinitesimal distances to the floor level. In my system the car is definitely stopped before the operator can move up or down the shaft or in the same direction. uable feature with this device is that it is adjustable as to how long aninterval must elapse before the car can be moved again, it being possible to malte the operator wait lifteen seconds, if desired, or adjustment can be made to accurately coincide with the exact stop of the elevator, allowing for drift and loading. Thus the stopping equipment, including dynamic braking, mechanical, electric band, or jaw brakes, are broughtto a condition of rest before the system is reversed or started, even in the same direction, thereby eliminating undesirable wear on the parts.

The timing device employed in my invention may be either mechanicallyI actuated by plungers, `electromagnetically operated by the controllermagnets or by the brake movement, or it may be electrically operated by a magnet placed in parallel with the shunt brake. The timing may be regulated by means of a dash pot over a time interval of fifteen seconds more or less as may be necessary in the particular system.

A centrifugal governor is employed in the system for obtaining protection against overspeeding into the terminals. The centrifugal governor contacts are placed in parallel with the contingent limit switch which is mounted on the car, insuring that the car must be on slow speed. when approaching either terminal or car will stop. This avoids the occasion of serious accidents which have occurred due to cars crashing into terminals at high speeds. Theccentrifugal type of governor' and the contingent limit switch connected in the circuit as I have illustrated prevent accidents such as these are independent of the derangement of the equipment or the operators forget-ulness. The operation of the A verv val- IDO contingent. limit switch forces all apparatus yto be returnedy to the Off positionr after functioning, thus preventing tele raphinv.

f of switches if the control switch is eld in t e yan installation of sayk twentyr floors served kby an elevator.y each Vfioor has been equipped with a door switch. In the event that one or more of the switches failed to make7 contact, eachof-the switches must be eventually inspected to determine whether or not the contacts are in proper order. This has necessitatedthe removalL of sheet metal `covers dust proof.`

'from` each of the switches until the defective contact. has been found.' `Often every cover may be'4 rremoved before the ydefect is dis# covered, which covers mustbe subsequently replaced. By my present construction the contacts kfor 4the door switches are plainly visible atfall 'times through an* aperture closed by clear mica or othery transparent material intheswitch cover. This allows the ready inspection ofthe switch contacts without removalk of the box'covers and at the same time' maintains the switch bug and My invention will be `more clearly understood by reference to the following specification and accompanying drawings, wherein Figure l is a diagrammatic view showing the arrangementof the'elevator equipment and the lelectrical connections thereon for performingthe obj ects of the invention, with modified circuit connections,v illustrated in ,dottedlines; Fig. 2'is a side elevation partially in cross section showing the construction of the timing relayfor the non-plugging device; Fig. 3 is aafront yelevation lof the timing relay illustrated in Fig. 2; Fig. l is a fragmentary view f showing kank electromagnetic operating means for thetilningrelay;

Fig. 5 is a front view of the centrifugal governor used in my 'elevator system 'with'the cover of the casing removed'to show the interiorparts. Fig. 6 is a side elevation of the governor construction; Fig. 7 is a front view of the sequence relay. which'I employ in thek circuit arrangement of `my invention; and Fig. 8 .is a side view the sequence ,relay illustrated inrFig. 7.

R Lferring` more particularly tokk Fig.` l- ,of the drawings thc circuit may. be traced from vthe line Llf'Hq through .'P resistance, it

being assumed that car switch l3()y is off position, throughrcontrol fuseV F, through OS orf overspeed governor contacts,

, through onesideofifinalup, final down and `car lsafety switch contacts .X1-4X.. Hereit will be observed that L14- after going through these contacts, feedsv coil onF. B.' switch and to one side ofy the vcircuit for Ui, U2 and D1 and Daf'rheends of'Ui 4andjiU2, and D1 and D2, go directly tothe ltop stationary contacts 78 and 7 9 on the double kpole-double throw sequence relayl SR. Assume now that a circuit is closed through door contacts D, lthe contacts A of the interlockon the acceleration movement, the contacts of the governor G, the B contacts on the timing relay, the overload relay contacts C, throughy the circuit passing through the over-speed governor switch OS and through the circuit containing 'the final limit contacts Nl-N2, then the four pole double throw relay SR will be closed. The car switch must be in center to allow relay SR to go in,

even if everything is closed after car switch is Y ofi position to allow'relay SR to come in, before carV switch 30 isthrown to on position. Thatis to say, itis necessary that the relay coil 34 be first energized by the closing of the door contacts D and the contacts in the circuit bet-ween line'. L1m and L2- as follows: From line L1 through resistance P through fuse F, through contactsy X4; on the overspeed governor switch OS, through the finall limit up switch X3, the final limit ydown switch'X2 through the car safety switch contacts Xl-X, through conductor R interlock fingers or 56, through contingent limit switch 31, contact C, door contacts D, sequency relay resistance 38, sequence relay coil 34, contacts N-Nl, on final limit down n If car switch 30 is thrown s to.on,position first and` then final contacts closed, it is necessary to return car switch to Cil switch, contact-sNl-NQ oiifinal limit up Y switch` fuse 35 and line L2. Thisarrangement thereby avoids the danger of accidents by preventing the starting of the elevator or the' functioning of the sequence relay until the' door contacts are vinitially closed. y Y

',The P resistance as shown 'is not an essential. part of my system. I prefer to conynect thepoints 90 and 91 inthe circuit posiforce, vgenerated bythe rotating armature buildsfup, acting to keep the linecurrent normal.y The interlock onv57 must be closed before the'direction switches or FB ycan close. l

When vusing the Pi'esistanceit is necessary to build the switches Vveryi carefully, and v i llu The reason l lf) adjust the P resistance accurately However, with a shunt circuit across the contacts W these refinements are not required.

Vith car switch in center the closing circuit for relay SR can be traced as follows: Trace Ll-lthrough or over bridge ot P resistance, through fuse F, through X4- Xi-XQ-Xl-*Q over R, through A, through B, through contingent limit switch 3l, which in stopped position of equipment is shorted by governor' contacts 32, through overload relay contacts C, through door contacts D, through sequence relay coil resistance 33, through sequence relay coil 34 to N,-N2, through fuse 35, to L2.

It will be noted that sequence relay coil 34 is in series across the line with the sequence relay resistance The ohmic value ot' the resistance 33 is properly proportioned with that of the coil 34 so that the low .current which flows in the circuit, plus a large number of turns on the relay coil 34, provides ample pulling capacity to close the relay armature ot relay SR. The sequence relay resistance is always high enough so that it can be placed across the supply lines continuously, by itself, without injury.

With the relay SR closed, the car switch 30 is thrown for example, to the Up position and the rest of the circuits may be traced.

Starting trom `LQ, through fuse7 35,

i through NQ-Nl-N in car switch 30, current now goes two ways, through contact 2 to Up stop switch 3G, through linger 37 on relay to stationary stud on relay 38, to U2- to Ul, through F. B.coil,through XXl-X2-X3 X4, through fuse F, through P or over bridge on P, to the line Lldr. This brings in Up direction switch which energizes the armature circuit, and F. 13., which shorts resistance in shunt field out thus giving lull ield strength vfor. starting and also energizing the brake coil. As soon as the F. B. switch goes in, the shunt brake coil is energized. Across the brake coil is placed the coil on the timing device, solenoid 39 in Fig. 4. This coil causes the armature 40 to project the plunger 4l ot the timing device B, thus breaking the circuit ot the relay coil at B b v the removal of the bridging member 4Q from between the spring pressed fingers 43 and 44. The timing device includes a dashpot 45 with a reciprocal piston 46 therein with a time adjusting means 47 carried thereby to control the operating period of the down stroke. ln the construction illustrated, I am able to introduce a time period of from zero to itteen seconds. The initial adjustment when once made remains in adjustment for indefinite periods. rPhe piston 46 is connected by piston rod 48 with a bell crank 49 pivoted at 50. An adjustable weight 51 is provided on one arm of the bell crank 49. The lower arm 52 of the bell crank is connected at 53 with the plunger` 4l in such manner that the position of the plunger may be controlled by the abutment ot a rod 54 actuated by either the reverse switches, the brake magnet, 0r by an individual magnet such as the magnet 39 in Fig. 4. The timing device B forms the`non plugging control for the ele fator system and prevents automatically the reversal and inching of the motor until the entire elevator equipment has come to a full stop. Most elevator motor armature failures are .caused by two things-oil and dirt collecting on the armature causing deterioration of the insulation and. abnormal plugging current. By far the greater number of elevator motor troubles as well as mechanical troubles are caused by plugging Plugging is the act of going trom vlull speed in one direction to full speedt in the other direction without lirst coming to a full stop before reversing.

The device of my invention automatically prevents reversal of the motor until the entire equipment has come to a full stop.

The plunger 41 may be mechanically actuated as heretofore described' in lieu of the electrical method illustrated in Fig. 4 by the reciprocatory movement of the plunger 54 as illustrated in Figs. l and 2.

The setting ot the accelerating dashpot45 and timing device 47 controls the period of opening and closing of the relay circuit. Then.y as the equipment comes up to speed, the short circuit across the contingent limit switch 3l caused by the governor contacts 32 is removed. p

However, the sequence relay SR does not fall out. because on the bottom of theV reverse switches are normally open interlock fingers 55 and 56 which are closed, as the reverse switch' closes, thus creating a circuit from Ll-lthrough or over bridge of P resistance, through fuse F, through X4-X3-X2-X1X, over R through intei-lock on bottom ot U switch 55 down through contingent limit contacts 31, back through overload relay contacts C, through door contacts D, through resistance 33, t-hroughicoil 34, back through N-N1-N2- through fuse to -L9., thus'shorting contacts on A and B.

The acceleration circuit does not require description here other than to point out `that the A Contact is opened by the accelerating movement. The A contacts serve a protection for the armature of the. driving motor soA that the motor cannot be started unless all of the armature resistance is in the circuit. The contacts A are mounted. on the accelerating device and are closed when the acceleratingr fingers are in open position.

With the circuits set as described the elevator will be running up the shaft at full speed'. The speed governor G on the motor has by centrifugal force, opened its contacts 32.A Thus it can be seen that if the contingent limit switch contacts 31 were to open, the SR coil circuit 34fwould be broken and the car would stop. e However, in ordinary roperation, asthe car approacheseither terminal it vis slowed down by the opening of either the upfslowdown switch or the down slowdown norfcontacts 32. fail to short-the contingent limit contacts 31 and when the' contingent limitis opened the car stops sincefthe coil cire cont-act at 42, as t N'to car switc 30throu h up'stop switch 36,-

to Contact 37 on relay S ,to bottom `station v cuit 34 is broken. l

` Assume that the car is slowing down correctly at terminals the 'action of theAcontact maybe observed. As soon as the 'acceleratingmovement 57 begins to operate the A conytact is opened andi fail to closev when car switchfhanv le 30 is rreturned'tokof and then'to onpositions con trol will not function.

it should for an reason,

The accelerating movement 57 7operates to cutout armature re-y sistance in accordance with the speed control ofthe elevator motor. v j f l l The timing' device B having actuating winding 39 purposely slows "up its making e` coil is deeenergized. This time lagr can be anyperiod desiredbut is usually just enough t0 force'the yoperator to allow the equipment to come to`rest,"before throwingfcar switch 30 in either up or down direction, or in the same direction.

Assuming that e' equipment is'at rest, with car switch 30 in center, andone'of door con'- tacts D open, with every other'contact normal.

yPresume thatthe operator throwscar switch 30to upposition and then closes door contact D, the car will not start or control function. The reason for this will be observed by .tracin "the, circuit as ollows` i Vith the car-switch 30 in the up position and a door contact D o en, the 'circuit can be traced startin vwith 2, through N2-N1- ary contact 63 on vrela. up through vbottom fingers 62 ony relay,'t rough ,resistancev 33, through door contacts D, through contacts C i onfoverload relay, through contingent limit t vswitch contacts 31,' through B, throu h Ato R, through X-Xl-XQ-XS-Xft, t rough fuse Fitor -l-Ll, thus puttingresistance 33 directlyA across thefline, and shunting the se# quence relay coil 34. Therefore, as long as the vcar switch '30 is held in the on` position, if

kthe final contact of'anyof the'devices ismade aftercar kswitch is thrown to on pos1ti'on, the resistance 33 remains across the sup ly lines andthe relay remains in vthe 'norma' ly .open position, with its coil 34 shorted or shunted. However, if the car switch is brought to the y relay is to force the operator to first close the doors to'whicli the door contact Dis attached and then Amove the lever 30 yto the on position. If it is done in any other way, the car will not move. This does away with the dangerous practicev 4ot an operator standingy at a ioor, with thevdoor open, admitting passengers ywith the 'car switch in the on position, then closing the door and starting the 'elevator by means of the ,door'contact This is done eX- tensively where norelay is employed to preventsuch action.

y The non-plugging -eature introduces adelay into the circuit, such delaybeing pre-de-A termined andy adjusted to coincide with the exact stoppage of the equipment. This makes it 'impossible to either reverse the equipment or go inthe same direction, or start at e all, until the contact, shown at B is closed.` If

the car switch'30 was to be moved before contact Bv closes, the control would not function,

independent of the'y fact that the car switch may be held in the on position indefinitely.'

The opening of any of the devices lin the N2 circuit ory the X4 circuit gives the same results as any opening in the relay circuit proper.

lSlQ/-lli-ly are opened,-they will break a somewhat larger current than will the contacts in circuit with thecoil 34.`v This is due to the 'fact that these'contacts feed, in addi-v. tionto'ithe relay, circuit,fthe FrB, and reverse switch f' coils," UlQ-UZ-#Dl-DZ- Thisv docs not oi'er seriousdiiculty however for thereason that these contacts which handle the some` what larger current arevery rarely `broken and the current handled is not, ordinarily, over'one-half to three-fourths of an ampere. Since these contacts' are in a fairly large switch, the current can usually be handled fairly well, especially with the infrequent operation. i

n My system has the greatadvanta'ge, how'- ever, of ymaintaining the current low across the door contact switches DyTh'ese switches are usually installed where space ris at a premium. The switches are vnormally v very small and the contacts are necessarilyy crowded. The spacing between'contacts and between ycontactsfand ground potential of the opened with the car switch in on position, the arc may be, and often is, large enough to cause a jump to ground or hang on across the contacts. Either condition is liable to cause operating trouble. In my arrangement of circuits and relay this ditliculty is eliminated.

I have shown in Figs. and 6 the details oi construction ot the governor wherein reiference character designates the driving motor armature shattcarrying a central bolt 66 on which the elements of the governor are mounttacts may be mounted upon an insulating block 77 within the governor housing in such position that the moving contacts may be readily pressed thereagainst; The centriiiugal relay may be used with either alternating current or direct current and is normally set to open at a car speed of from forty to seventy feet per minute. It is frequently mount-ed on the motor or safety governor.

In Figs. 7 and 8 the construction of the sequence relay has been more clearlyy illustrated with the lower contacts 63 and 61y and the upper contacts 7 8 and 79. The resistance unit 33 is mounted on the rear of the panel 80 which supports the relay. The insulated plate 8l carries the contact lingers 37, 8l, 82 and S3, the latter comprising contacts 62 the plate being pivotally mounted as represented at 84C. As heretofore explained, the relay does not break heavy current, thus ygiving in-l definite life to the contacts Aas they are subjected to mechanical wear only. The spring tension 85 enables the relay to operate quickly without lag. A

As heretofore noted the door contacts D are housed in such manner that they may be readily observed without removing the cover from the box.

While I have described this invention with relation to elevator equipment, it will be apparent that the principle of Ythe invention may be embodied in protective systems such as a lock system for automobiles whereby the opening of the door of the car actuates a contact which will lock up theent-ire system. This equipment upon an automobile is particularly desirable in a closed car inasmuch as it may be arranged so that the car cannot be started until all the doors arel closed and locked. This prevents doors from being torn oli by startingand tampering.

It will be understood that other modifications may be made in my invention and that I intend no limitations .upon theV invention other than are imposed by the scope of the appended claims.

lllliat I claim and desire to secure by Letters Patent ot' the United States is as follows:

l An elevator.system comprising in combination an elevator, driving apparatus for saideievator, a controller for actuating said driving apparatus, a sequence relay in circuit i h. said controller, and circuit closing means adapted to introduce a time lag in the operation ot said sequence relay whereby said controller is prevented from reversing the direction ot movement ol said elevator until said elevator has been brought to a condition 01"' rest.

2. An elevator system comprising in cornbination an elevator, driving apparatus, a controller for actuating' said elevator, circuit connections including a source of energy and saidv driving` apparatus, door contacts interposedv in said circuit, means for controlling the opening and closing of said circuit over variably adjustable time periods, and means whereby said door contacts must be closed prior to the actuation of said controller before aid elevator can be placed in motion.

3. An elevator system having a plurality ot control circuits, an elevator, driving apparatus for said elevator, a controller for governing the movement of said elevator in either ot two directions, ya door contact in one `of said cont-roll circuits, means for controlling the opening and closing of said circuits over variablyadjustable time periods, and means whereby said door contacts must be initially closed prior tothe operation of said controller before said elevator may be moved in either direction.

` et.. An elevator system having a plurality of control circuits, an elevator, driving apparatus for said elevator, a controller for governing-the movement ot said elevator in either of two directions@ door contact invone of said control circuits, a sequence relay in each of said control circuits, means for controlling the opening and closing ot' said circuits over variably adjustable time periods, and means whereby said sequence relay may be closed by sequentially closing said door contacts and next actuating said controller tomove said elevator in either direction.

5. An elevator system having a plurality of control circuits, an elevator, driving apparatus for said elevator, a controller for governing the movement'of said elevator in either' of two directions, a door contact or multiple number of door contacts in one of said control circuits, a sequence relay commonto allot said control circuits, a coil arrangedto magnetically actuate said relay, a resistance,.means Afor controlling the opening and closing of ysaid circuits over variably adjustable time periods, v

and circuit connections whereby said coil is yshunte'd bysaid resistance when said controller is actuated prior to the closing of said door contact and said coil placed 1n series With'said resistance when said door contact is closed prior to the actuationy `of said controller. i Y 'n 6. An elevator systemhaving a plurality of control circuits, an elevator,`driving apparatus for said elevator, a controller for governing the movement of said elevator in either of two directions, a door contact in one of Said control circuits, a sequence relay common to said circuits, a timing relay insaid door contact circuit and means whereby said driving :l5`

apparatus may be actuated when said door contacts are first closed followed by operation of said controller, saidtiming relay being yactuated' at each reversal of saidycontroller forbringing said driving means toa condition of rest intermediate a change 1n direction of movement of said elevator.

7. An elevator sytem having a plurality of control circuits, an elevator, driving apparatus for said elevator, a controller for governing the movement of said elevator in either of two directions, adoor contact in one of said control circuits, a sequence relay common to said control circuits, means in one of said control circuits for interrupting the energy supply system simultaneously with each reversal of the controller overa period of time for bringing said driving apparatus to a condition of rest prior to the next impression of the lenergy supply upon the control circuit, saidcontroller being arranged to actuate said driving apparatus only when the actuation of said controller is subsequent to the closing of said door contact for moving said elevator in either direction.

In testimony whereof I affix my signature.

HARRY BENJAMIN GOLDMAN.

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