US2307542A - Interlock for elevator doors - Google Patents

Description

Jan. 5, 1943. A. E. PRINcE 0 INTERLOCK FOR ELEVA' IOR DOORS I Filed-March 1a, 1942 4 She ets-Sheet 1 my H 58' m (PM INVENTOR BY ATTORNEY Jan. 5, 1943. A. E. PRINC E' INTERLOCK FOR ELEVATOR 1200125 4 Sheets-Sheet 2 Filed March 18, 1942 INVENTOR ATT RNEY A. E. PRINCE. 2,307,542

I 4 Sheets-Sheet 3 I III! I 4 ML llllkl RU F W Jan. 5,1943.

IN'IIERLOCK FOR ELEVATOR: nooas:

Filed March 18, 1942* ATTORNEY A. E. PRLNE iN'rEii'LocK FOR ELEVATOR D0035 Jan. -5, 1943.

F iled March 18. 1942 4 Sheets-Sheet 4 FIGlO FIGS M INVIENTORIZ ATTORNEY Patented Jan. 5, 1943 UNITED smr s e ENT OFFICE INTERLOCK FOR ELEVATOR DOORS Application March 18, 1942, Serial No. 435,124.

13 Claims.

The invention relates to interlocks for elevator hatchway doors.

In elevator installations in which the operation of the elevator car is controlled by the passengers and intending passengers themselves and in which the hatchway doors are manually operated, it is customary to provide each door with a lock and to provide a retiring cam on the car which acts, when a stop is made at a floor, to unlock the door at that floor. Contacts are associated with the lock to prevent operation of the car unless the door is closed and locked. Also contacts are usually provided to prevent energization of the retiring cam unless the door is closed. The invention is' especially directed to interlocks of this character.

The object of the invention is to provide an interlock which is reliable in operation and which is of simple yet fool-proof construction.

The invention involves the construction of an interlock in which all access to the circuit controlling elements is eliminated and in which any unwarranted manipulation of the interlock is obviated. The invention also involves a latch for latching the door in closed position, a magnet carried by the door for controlling the operation of the latch, and locking means for locking the latch in latched position, thereby locking the door.

In carrying out the invention according to the arrangements which will be described, the latch is mounted in an interlock housing in position to enter a recess in the edge of the door when the door is closed. An opening is provided in the housing for the latch, this opening being closed by the latch. The magnet for controlling the latch is a permanent magnet and is carried inside the door. When the door is closed, the magnet acts in conjunction with an armature carried by the latch to move the latch to latched position. A lock member in the housing is moved into position to lock the latch in latched position when the car is to be operated, thus locking the door in closed position. Contacts are operated by the latch to prepare the circuit for the retiring cam for operating the locking member. Also contacts are operated by the locking member which act to prevent operation of the car unless the door is closed and locked. All these contacts are within the interlock housing and as the housing is entirely enclosed, the opening in th housing for the latch being closed by the latch, the contacts are inaccessible. When the car is stopped at the floor, the locking member is moved to unlocking position by the retiring cam.

- The latch is formed so that, when it is freed by the locking member, it forces itself out of the recess in the door against the force of the permanent magnet upon the door being moved toward open position. i

A general idea of the invention, the mode of carrying it out which is at present preferred, and various features and advantages thereof will be gained from the above statements. Other features and advantages of the invention will be apparent from the following description and appended claims.

In the drawings:

Figure 1 is a schematic representation of interlocking mechanism embodying the invention applied to a swing type hatchway door;

Figure 2 is a view in elevation of the interlock with parts broken away;

Figure 3 is a view in section taken along the line 33 of Figure 2 Figure 4 is a View in section taken along the line 4-4 of Figure 2;

Figure 5 is a view in section taken along the line 55 of Figure 2;

Figur 6 is a fragmental detail of the portion of the mechanism of Figure 2, illustrating the interlock in unlatched condition;

Figure 7 is a fragmental detail taken along the line l'l of Figure 6;

Figure 8 isa iragmental detail taken along the line 8-8 of Figure 2;

Figure 9 is a view similar to Figure 2 of interlocking mechanism embodying the invention applied to a sliding type hatchway door; and

Figure 10 is a View similar to Figure 6, illustrating the interlock of Figure 9 in unlatched condition.

'Reierring first to Figure 1, the elevator car H1 is illustrated as stopped at a floor. The hatchway door at that floor is designated H. The door is a swing door and is supported by hinges I2 and 13 secured to the door casing I l. The

casing is embedded in the hatchway wall and rests on a sill plate l5 in the floor IS. The lower hinge I3 is connected to a door check and closer in a box ll embedded in the'floor. The door is illustrated as of hollow metal construction. It is provided with a fixed knob 18 for pulling it open from the outside when the door is unlocked.

The interlock is positioned near the top of the door. A non-magnetic plate 21), secured to the edge of the door, is provided with a recess 2| to receive the latch, thereby forming a keeper. The latch comprises a pivoted arm 23 having 'a hooked end 22 for extending into the recess.

embedded in the door casing, at least the face of the housing being of non-magnetic material. The hooked end of the arm extends through an opening 29 in the face of the housing. The arm carries an armature adapted to be attracted by a permanent magnet 26 mounted on plate 28. This magnet acts to pull the latch into the latching position illustrated when the door is closed. The latch is locked in this position by a locking member 21 secured to a shaft 28 pivotally mounted in the housing. This shaft extends outside the housing where it is provided withan operating arm 38 having a roller 3| on the outer end. The locking member is biased to locking position by arm 30 and a spring 32 between a wall of the housing and the lug 331 depending from the locking member.

The locking member 21 is moved to unlocking position by a retiring cam 34 mounted on the elevator car. This cam is retracted electromagneticallyas by an electromagnet 31 mounted on the car sling 39. A chain 35, passing over an idler pulley 38, connects the cam .to the armature 36 of the electromagnet. The energization .of the N electromagnet is controlled .by. contacts 40 in the housing operated by the latch. These. contacts are usually termed auxiliary. door. contacts. When the door is closed andrlatched, these contacts engage to permit the energization of the electromagnet to retire the cam. The retiring of the cam frees arm 30 permitting. the locking member to move into position behind the latch to lock the door. The locking member. when in this position engages contacts. to permit the operation of the car. These contacts whichare also in the housing are usually termed'door lock contacts. When the car makes astop at the floor, the retiring cam magnet isdeenergized, permitting the extension of the retiringcam. The retiring cam moves the operating arm counterclockwise, thereby moving the. locking member into unlocking position. This. opens the. door lock contacts and frees the. latch. arm.- The. hookedend of .the arm is bevelled as. wi1l be seen from later descriptionso that a thefdoonis.

pulled on from the outside. or pushed against .fromv the inside the latch is forced out .ofitthe recess 2| against the force of magnet 25L. This opens .the auxiliary door contacts and permits the. full opening of the door. The latch is biased by. it own weight to unlatching position so that;as the door movesaway from the. interlock housing .the. latch remainsin unlatching. position .where it cooperates .withthe locking member to retain the. looking member in the position to which it was moved by the retiring cam.

Details of construction of the interlocking mechanism are shown in Figures 2. to 8. inclusive to which reference may nowbe had. The non.- magnetic plate 20 is secured to the edge of the door byscrews 46, an opening 41 .being provided in theedge of the door to. accommodate the plate.

The permanent magnet 26is secured to plate 28 by a strap 48. Threaded studs extend inwardly from the plate, the strap being. clamped to. The magnet i of the horseshoe type preferablyoneofhigh coercion.

these. studs by nuts 5|- The latcharm 23 is pivotally .mountedon a pin positioned in aboss formed. in:the interlock. housing 24. 'This housinggcomprises;a; frame 561,

This arm is pivotally mounted in a housing 24 of non-magnetic material enclosed on the sides by side plates 51. The side plates are secured to the frame by screws 58. An opening 60 is provided in the door casing to receive the housin the housing being secured to the casing by screws 6| extending through the ends of the face 62 of the housing. An opening 59 is provided in the back of the door casing to provide access to the side plate on that sideof the housing enabling this Side plate to be removed to gain access to the inside of the housing. A stop 49 is formed on the door casing for stopping the door as it moves to closed position.

The opening. 2 9 inthe face of the housing and z the recess 2.l in plate 20 for the hooked end 22 pivot forthe latch. The, side members are joined; in the front opposite magnet. 26-: by. a r, web; 6.4:: to.

form asupport for the armature; 25'. The. armae ture is secured1to the latchzbygscrews 6.5: Agree cess 66; formedzin the. rear surface of face 62zto. receive; the, armature, decreases ,the1distance..be.-

tween the. armature. and the: magnet 2.6;. The

side members are alsozjoined in-ztheubackiby'another web 61' for" cooperating; withitheylockingmember 21 to- 1ock;the door inwclosed position.

The lockingmembergfl is .securedto shaftzq28. The: shaft: 28 isgpivotally.

as. by a set screw. 68'.- mounted in boss 10 formedo n-1.-th1e:,back.oiithev housing The, end;of the locking member; adjacent theweb. Bliscutiaway to. forma grecta-ngue lar key H. A rectangular-slow":slightlywlar er than .key I I is formed;- webyfi'l to permityth'e latch to; fall back over;the..key,;-wh rr:theadooris unlatched, as illustrated. in; Figure; 61,. When. the latch is released; it-is-broughtyto a:stop;by' the engagement; of the--webwith the: shoulders-v 13 formed on thelocking memberat the base-of Whenthe door is closed: and the; latch:

key 1 I is in latchi-ngpositionthe;door;is locked-;by rota:

tive movement of the locking member; by; its operating arm 30 into position placing the key-1 l' at an angle with respect to;slot 12 as shown-in Figure .4 which prevents 1movement ;of; theda-tch out of latchingposition; The operating arm 30 is secured to shaft 28 outside the ;cas i;ng.-by-a;.set screw. 15.- A spacing washerJG- is pinned-to shaft 28 between the operating arm andgthebackroi' the-housing. The operating roller 3| for army 30 is'mounted on ay-pin-l] secured-to.- the outer end of the arm. Biasing spring;32;for:the. locking; member extends between the ,lug; 33 depending. from the locking member and; the. opposite ;side. plate 51, being ;positioned-by--spring seats ,18 and 19 onthe-lug; and side plate;resp,ectivel-y,-

The door lock contactsoperated by the locking member 2'I- comp rises a p air-of. stationary-con struction the stationary; contacts are. bent back as-indicated in-Figure 5. The stationary con tacts. are. bridgedrby ycontact .springs. .-86 having contact tips. .81 for engaging the lowe-r. legs ot This block is secured to the backrwall -of*the Screws .841 secure the the stationary contacts. These springs are mounted on an insulating block 88 secured as by screws 99 to an extension 9| from the locking member 21. Bridging piece 92 is connected across the lower ends of the spring contacts, these parts being secured to the insulating block in an assembled relation by screws 93. The contact springs rest in troughs 94 in insulating block 88, the angles of these troughs being such that the contact springs are swung away from the bottoms of the troughs to provide good contact engagement when the door is locked and are picked up by the bottoms of the troughs to disengage the contact points thereon from the stationary contacts before the key II becomes parallel with slot I2 to unlock the door.

The auxiliary door contacts comprise a pair of stationary contacts 95 and 96 mounted on an insulating block 91. To facilitate obtaining access to these contacts, the block is arranged on a dovetail slide 98 secured to the top of the housing as by screws 99. Terminal screws I99 secure these contacts to the block and also serve for connecting the contacts in the system. The stationary contacts are bridged by contact springs I9I having contact tips I92. These springs are mounted on an insulating block I93 secured as by a screw I94 to latch arm 23. The insulating block is positioned by a shoulder I95 formed thereon which engages the upper end of the web 61. A bridging piece I95 is connected across the lower ends of the spring contacts, these parts being secured to the insulating block in assembled relation by screws I9I. The contact springs rest in troughs I98 in insulating block I93, the angles of these troughs being such that the contact springs are swung away from the bottoms of the troughs to provide good contact engagement when the door is latched in closed position and are picked up by the bottoms of the troughs to disengage the contact points thereon from the stationary contacts before the hooked end of the latch moves out of the recess 2| in plate 29 to unlatch the door. An opening H3 is provided in the top of the housing for the connecting wires, a conduit connector H4 being illustrated as secured to the housing in this opening.

The extreme end H9 of the hooked end 22 of the latch arm is bevelled back as indicated in Figure 3. The purpose of this arrangement is so that the edge H I of the recess 2I in plate 29, by engaging this bevelled portion as the door is moved toward open position under conditions where the latch is not locked, forces the latch inwardly of the interlock housing against the force of magnet 26 to unlatch the door. The opening 29 in the front plate of the housing is provided with a, flange H2 which extends inwardly of the housing along the side opposite bevelled edge H9 and top and bottom of the opening to prevent access to the inside of the housing around the bevelled portion H9 of the latch, when the latch is released and the door is open. This entirely eliminates access to the circuit controlling mechanism of the interlock from the outside.

Although when the door is unlatched and open the hooked end of the latch is flush with or back of the face of the interlock housing which renders it extremely difiicult for anyone manually to pull the latch into latching position, it may be desirable to provide mechanism to positively retain the latch in unlatched condition. An arrangement for effecting this operation has been illustrated. This comprises member H5 of ma netic material pivotally mounted on'a pin H6 extending into a lug I I1 formed on the rear surface of the face of the housing. This pivot is near the bottom of the member so that the member is biased by its own weight, augmented by a spring if desired, for clockwise movement about its pivot as indicated in Figure 2. In the bottom of this member on the Opposite side thereof is a notch H8, for cooperating with a pin I29 extending from the side of the latch arm 23 to retain the latch in its unlatched position. When the door is closed the member H5 is in the position illustrated in Figure 2. As the door is opened and the latch moves clockwise about its pivot into unlatched position pin I29 moves beneath the notch I I8 and the member falls clockwise into position with the notch over the pin as illustrated in Figure 6 to hold the latch in unlatched position. Thus unwarranted manipulation of the interlock is entirely obviated.

In operation, assume that the door is closed and latched as indicated in Figure 2 and that the retiring cam has been extended to operate arm 39 to position key II parallel with slot 12 in the latch 23 as indicated in Figure 7. As the door is moved to open position the edge III of recess 2I pushing on the bevelled portion H9 of the latch, forces the latch clockwise about its pivot into unlatched position against the force of magnet 26. During this movement contact springs I9I disengage stationary contacts and 96 to open the auxiliary door contacts before the hooked end of the latch arm is moved out of recess 2|, thereby assuring that the auxiliary door contacts are open when the door is unlatched. As the door moves outwardly the magnet reaches a position Where it is no longer able to move the latch toward latching position so that the latch falls all the way out with the web 61 resting against shoulder I3 of locking member 21. Also, with further movement of the door the magnet releases member I I5 which drops into position with the notch H8 over pin I29. This holds the latch in unlatched position while the door is open.

Upon closure of the door, as it nears the fully closed position it reaches a point where the magnet pulls member II5 counterclockwise about its pivot releasing the latch so that as the door moves to fully closed position the latch is pulled counterclockwise about its pivot by the magnet into latching position. After the hooked end of the latch has moved into recess 2| and just before the latch reaches its final position the contact springs of the auxiliary door contacts bridge the stationary contacts preparing the circuit for the retiring cam magnet.

Upon a button being pressed to call the car, the retiring cam magnet is energized retracting the cam and permitting locking member 21 to be rotated into locking position with the key II at an angle to slot I2. After the latch becomes locked and just before the locking member reaches its final locking position, contact springs 86 bridge stationary contacts 89 and 8| to permit the operation of the car. As the car comes to a stop at the floor for which the push button was pressed, the retiring cam magnet is deenergized extending the cam to cause the opening of the door lock contacts and thereafter the unlocking of the latch of the interlock for the hatchway door at that floor, permitting the opening of the door as above described.

It is to be noted that as the key II is in the slot I2 when the door is open, should the retiring cam magnet accidentally become energized as for example as the resultof a ground in the door.

circuit for the retiring cam..magnet; the slot prevents rotative movement :ofthe locking member 21 to close the door'lock contacts-after the cam has-been. retired, thereby preventing operationof the car.

Theinvention-is also applicable to sliding doors and anarrangement for sliding doors is illustrated in FiguresQandlO; The door I30 is of hollow metal construction and has anon-magnetic-plate I3I secured thereto in the opening l33' in the edge of the door. A permanent magnet I34 is secured to the; back of the plate by a-strapl35- asbefore. A recess I36 is provided in the plate to receive the latch, thereby forming:

a keeper; The latch comprises a catch member I37 'pivotally mountedon a pin- I38 supported by lugs I39- inthe' interlock housing. Thiscatch extends through an opening I40'in theface of the housing andis provided witha: hooked end IQI- for extending into recess I36-.in plate I3I.

Portions I42 and I43 of the catch arecircular,

beingof a'radius swungfrom the center of pivot pin I38 such as-to completely cutoff the opening I 40 Thearm I44 of the latch-isseparate'fromthecatch-and is cut awayin'backofthe-catch" as.

as- M; this cut away portion engaging theback of thecatch to hold'thecatchin latchingposition asillustrated' in Figure'9. The hooked end ofthecatch hasa bevel-led portion I45 which isengaged by the top edge ld-l of 'recess liifi whenthe door is pulledopen to force the latch counterclockwise about 'its pivot into position re1eas-- ingthe latchand permittin'g full opening of the During' this unlatching operation, the lower end I48-of the *catch. pushes the latch'arm I44 clockwise about its pivot against the force of magnet I34so that as-the door movesinto open position the latch armfalls: into position with the web 150 against-'the shoulderlt formed on the-lockingmemberfil; as illustrated inFig- It'is preferredthat the catch be biased to un-- latching position about its pivot and a stop I5I is formed onthe latch to engage the rear surface of the face of. the housing to limit the movement of the catch in the unlatcliing operation.. However, if desired an additional bevelled sur-- face. I52 may be-providedon the hooked end of the catch as-illustrated to be engaged by the edge I41 of the recess to force the catch into unlatching: position upon closing of the door in case the catchhappens to be out of unlatched position at this time. position armature I53 on latch arm I44 is pulled to. attracted position and the latch armforces the'catch clockwise about its pivot into latching position. A stop I5 1 is formed onthe catchto engage-therear surface of the face of the housing to limit the clockwise movement of the catch.

Asbefore, uponthe cam being retired the locking- As the door' reaches closedthat manual release of the:latch..is. prevented. In-the caseof the slidingdoor,.manipulation of thecatch cananot releasethelat'chp The mag.- net acts 'to hold the doorin,closedpositionthereby minimizing rebound; The operating magnet being: on the =-doon prevents-the:unauthorized operation of the interlock-by. amagnetizable-plate;

An authorized service'man to do Work on. the. installation which-necessitates operation of the car with the-.door open musttherefore carry with him a magnet of at: least a certain strength for operating the interlock. The operating magnet being a permanentimagnet eliminates wires'be-- ing run int'othe door; The arrangement. de-

scribed is particularly suitable for flush. type hatchway doors as the interlock housing-may be mounted.- inside the door casing as illustrated with the magnet- 26- insidethe door, thesoperating arm and roller-being well to one side of the cam I0 (see Figure 3).

As many changes could be made in the above construction and manyapparently widely different -embodiments of this invention could be madewithout'departing from the scope thereof, it is intended that all'lmattercontained in the-above descriptioniorshown in the. accompanying drawings= shallbe interpreted asillustrative and: not

in a limitingsense- What is claimed'is:

l'. Interlock mechanism foranelevator hatchway door comprising; a non-magnetic plate se cured to the edge of the door and having arecess therein, a housingsecuredto the door casing, a

latch pivotally mounted in said housingian'd having a hook for entering said recess;' a permanent magnetinside the door and mounted on said plate; an armature carried'by said latch inposi? tion tozbe. attracted'by said magnetias the door is-c-l'osed to pull the latch-into position-to move the hookinto latching position'in said recess and thus latch the door inclosed position; and a-lock' ing-member: mounted in said housing biased-to locksaid latch in latching position.

2. Interlockmechanism for an elevator hatch- Way-doorcomprising; a non-"magnetic plate socured to theedge of the door and covering anopening in the 'edgeof the door; said plate having a recesstherein; a housing oppositesaid plate and extending into the doorcasing through an openingtherein, said housing having-a non-mag netic face with an opening therein opposite said recessand being secured tothe doorcasing; alatch having an arm-pivotally mounted in said housing and a hook forentering said recess from said opening in said housing face; a'permanent magnet inside the door'mountedon the rear-of said plate; an armature carried'by said 'latcharm' in position to be attracted by-said magnet as the door'is closed topull-the'latch-into position to move the hook in-to latching position in said recess and thus latch the door 'in closed position; anda memberpivotally mounted in said housing for" locking said latch'arm in-latching'position; said" member being biased 'to'lockinggposition;

3. Interlock mechanism for an elevator hatchway. door comprising; a=movable latch attached to thedoor casing; akeeper onthe-door forthe latch; 'anda magnet carried by the door for-pulling the latch into 1 position to engage the keeper as the door is closed to latch'thedoor, said latch having a surface for-cooperatingwith-an edge of theskeeperto forcethe latch into unlatched position zagainst theforceof said magnet as'the'door isiop'enedi 4'; Interlock mechanism-.foran' elevator hatch way door comprising; means forming a recess in the edge of the door; a latch pivotally mounted in the door casing and having a hook for entering said recess; a permanent magnet carried by the door for pulling the latch into position to move said hook into latching position in said recess as the door is closed to latch the door; and a locking member for locking said latch in latching position, said latch having a surface for cooperating with an edge of said recess when said locking member is released to force the latch into unlatched position against the force of said magnet as the door is opened.

5. Interlock mechanism for an elevator hatchway door comprising; a non-magnetic plate secured to the edge of the door and covering an opening in the edge of the door, said plate having a recess therein; a housing opposite said plate and extending into the door casing through an opening therein, said housing having a non-magnetic face with an opening therein opposite said recess and being secured to the door casing; a latch having an arm pivotally mounted in said housing and a hook for entering said recess from said opening in said housing face; a permanent magnet inside the door mounted on the rear of said plate; an armature carried by said latch arm in position to be attracted by said magnet as the door is closed to pull the latch into position to move the hook into said recess and latch the door in closed position; and a member pivotally mounted in said housing for locking said latch arm in latching position, said member being biased to locking position, said hook having a bevelled surface for cooperating with an edge of said recess upon the door being pulled open when said locking member is released to force said hook into unlatching position against the force of said magnet to unlatch the door.

6. Interlock mechanism for an elevator hatch- Way door comprising; a non-magnetic plate secured to the edge of the door and covering an opening in the edge of the door, said plate having a recess therein; a housing opposite said plate and extending into the door casing through an opening'therein, said housing having a non-magnetic face with an opening therein opposite said recess and being secured to the door casing; a latch having an arm pivotally mounted in said housing and a hook for entering said recess from i said opening in said housing face, said hook shutting ofi access to said housing through said opening in the housing face; a permanent magnet inside the door mounted on the rear of said plate;

an armature carried by said latch arm in position to be attracted by said magnet as the door is closed to pull the latch into position to move the hook into said recess and latch the door in closed position; a, locking member pivotally mounted in said housing in back of said latch arm and having a key for engaging the back of said latch arm to lock the latch in latching position, said locking member being biased to locking position, said back of said latch arm having a recess opposite said key; an operating arm for said locking member outside the housing; and a retiring cam carried by the car for operating said operating arm to move said locking member into position with said key in position with respect to said recess in said latch arm to free the latch arm for backward movement, thereby unlocking said latch, said hook having a bevelled surface for cooperating with an edge of said recess in said plate upon the door being pulled open when said locking member is in unlocking position to force said latch backward into unlatching position againstthe force of said magnet to unlatch the door.

7. Interlock mechanism for an elevator hatchway swing door comprising; a non-magnetic plate secured to the edge of the door and covering an opening in the edge of the door, said plate having a recess therein; a housing opposite said plate and extending into the door casing through an opening therein, said housing having a non-magnetic. face with an opening therein opposite said recess and being secured to the door casing; a latch having an arm pivotally mounted in said housing and a hooked end on said arm for entering said recess from said opening in said housing face; a permanent magnet inside the door mounted on the rear of said plate; an armature carried by said latch arm in position to be attracted by said magnet as the door is closed to pull the latch arm into position to move its hooked end into said recess and thus latch the door in closed position; a locking member pivotally mounted in said housing in back of said latch arm and having a key for engaging the back of said latch arm to lock the latch in latching position, said locking member being biased to locking position, said back of said latch arm having a recess opposite said key; an operating arm for said locking member outside the housing; a retiring cam carried by'the car for operating said operating arm to move said looking member into position with said key in position with respectto said recess in'said latch arm to free the latch arm for backward movement, thereby unlocking said latch, the outer end of said hooked end being bevelled on its surface toward the hatchway for cooperating with the adjacent edge of said recess in said plate upon the door being moved toward open position when said locking member is in unlocking position to force said latchbackward into unlatching position against the force of said magnet to unlatch the door, said opening in said housing face being flanged inwardly around said hooked end to prevent access to the inside of the housing when said door is open; and means including a magnetizable member pivotally mounted in said housing and biased to position to cooperate with said latch armto hold the latch inunlatched position, said magnetizable member being attracted by said magnet as the door is closed to free the latch for movement to latching position.

8. Interlock mechanism for an elevator hatchway sliding door comprising; a non-magnetic plate secured to the edge of the door and covering an opening in the edge of the door, said Plate having a recess therein; a housing opposite said plate and extending into the door casing through an opening therein, said housing having a nonmagnetic face with an opening therein opposite said recess and being secured to the door casing; a latch comprising a latch arm pivotally mounted in said housing and a catch having an arm extending through said opening in said housing face with an upwardly extending hooked end for entering said recess to latch said door, said catch being pivotally mounted in said housing in position to be operated by said arm into latching position, and shutting ofi said opening in the housing; a permanent magnet inside the 'door mounted on the rear of said plate; an armature carried by said latch arm in position to be attracted by said magnet as the door is closed to pull the latch arm into position to move said catch into position with its hooked end in latching position in said recess, thus latching the door in closed position; a locking member pivotally mounted in said housing in back of said latch arm and having a key for engaging the back of said latch arm to lock the latch in latching position, said locking member being biased to locking position, said back of said latch arm having a recess opposite said key; an operating arm for said locking member outside the housing; and a retiring cam carried by the car for operating said operating arm to move said locking member into position with said key in position with respect to said recess in said latch arm to free the latch arm for backward movement, thereby unlocking said latch, the surface of said hooked end toward the housing being bevelled for cooperating with the upper edge of said recess in said plate upon the door being moved toward open position when said locking member is in unlocking position to force said latch backward into unlatching position against the force of said magnet to unlatch the door.

9. Interlock mechanism for an elevator hatchway door comprising; a keeper on the door; a housing secured to the door casing opposite said keeper; a latch mounted in said housing, said housing having an opening therein through which the latch extends to enter said recess, access to said housing through said opening being shut off by said latch; a magnet carried by the door for operating said latch; and contacts inside said housing controlled by said latch.

10. Interlock mechanism for an elevator hatchway door comprising; a keeper on the door having a recess therein; a housing secured to the door casing opposite said keeper, said housing having an opening therein opposite said recess; a movable latch mounted in said housing for entering said recess from said opening in said housing, said latch shutting off access to said housing through said opening; a permanent magnet carried by the door for pulling said latch as the door is closed into position in said recess to latch the door in closed position; means in said housing for locking said latch in latching position; contacts inside said housing closed by said latch u when said door is latched; and additional contacts inside said housing closed by said locking means when said latch is locked.

11. Interlock mechanism for an elevator hatchway door comprising; a plate on the edge of the door having a recess therein; a housing opposite said plate and secured to the door casing, said housing having an opening in the face thereof opposite said recess; a latch having an arm pivotally mounted in said housing and a hook for entering said recess from said opening, said hook shutting off access to said housing through said opening; a permanent magnet inside the door mounted on said plate; an armature carried by said latch arm in position to be attracted by said magnet as the door is closed to pull the latch arm into position to move the hook into said recess and latch the door in closed position; a member in said housing operable to lock said latch in latching position; contacts inside said housing closed by said latch after said door is latched; and additional contacts inside said housing closed by said lock member after said latch is locked.

12. Interlock mechanism for an elevator hatchway door comprising; a non-magnetic plate secured to the edge of the door and covering an opening in the edge of the door, said plate having a recess therein; a housing opposite said plate and extending into the door. casing through an opening therein, said housing having a nonmagnetic face with an opening therein opposite said recess and being secured to the door casing; a latch having an arm pivotally mounted in said housing and a hook for entering said recess from said opening in said housing face, said hook shutting off access to said housing through said opening in the housing face; a permanent magnet inside the door mounted on the rear of said plate; an armature carried by said-latch arm in position to be attracted by said magnet as thedoor is closed to pull the latch arm into position to move the hook into said recess and'latch the door in closed position; a locking member pivotally mounted in said housing for locking said latch in latching position; auxiliary door contacts inside said housing closed by said latch after said door islatched; and door lock contacts inside said housing closed by said locking member after said latch is locked.

l3. Interlock mechanism for an elevator hatchway door comprising; a non-magnetic plate secured to the edge of the door and covering an opening in the edge of the door, said plate having a recess therein; a housing opposite said plate and extending into the door casing through an openin therein, said housing having a'non-mag netic face with an opening therein opposite said recess and being secured to the door casing; a

latch having an arm pivotally mounted in said housing and a hook for entering said recess from said opening in said housing face, said hook shutting oif access to said housing through said opening in the housing face; a permanent magnet inside the door mounted on the rear of said plate; an armature carried by said latch arm in position to be attracted by said magnet as the door is closed to pull the latch arm into position to move the hook into said recess and latch the door in closed position; a locking member pivotally mounted in said housing in back of said latch arm and having a key for engaging the back of said latch arm to lock the latch in latching position, said locking member being biased to locking position, said back of said latch arm having a recess opposite said key; an operating arm for said locking member outside the housing; a retiring cam carried by the car for operating said op erating arm to move said locking member into position with said key in position with respect to said recess in said latch arm to free the latch arm for backward movement, thereby unlockin said latch, the outer end of said hook having a bevelled surface for cooperating with an edge of said r cess in said plate upon the door being moved toward open position when said locking member is in unlocking position to force said latch backward into unlatching position against the force of said magnet to unlatch the door; a pair of stationary contacts in said housing; contacting means carried by said latch arm for bridging said contacts after said door is latched; an additional pair of contacts in said housing; and contacting means carried by said locking member for bridging said additional contacts after said latch is locked.

ARTHUR. ENNIS PRINCE.

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