US2789527A - Emergency exit door lock - Google Patents

Description

April 23, 1957 Filed March 13, 1953 D. P. DAVIS EMERGENCY EXIT DOOR LOCK 3 Sheets-Sheet 1 FOR USE DiRECTlONS jhvenfor April 23, 1957 D. P. DAVIS EMERGENCY EXIT 000R LOCK 3 Sheets-Sheet 2 Filed March 15, 1955 fol" .7/71/(2/1 Dolly/as 1? 0a V/l? April 23, 1957 vjs 2,789,527

EMERGENCY EXIT DOOR LOCK Filed March 13, 955 s Shets-Sheet :5

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United States atent EMERGENCY EXIT DOOR LOCK Douglas P. Davis, Burbank, Calif. Application March 13, 1953, Serial No. 342,057 18 Claims. (Cl. 1168) This invention relates to locks and more particulariy to an improved panic lock for use on doors through which emergency exit can be made without resort to the use of keys.

In buildings in which large numbers of people are present, it is necessary to have sufficient exit doors to permit rapid escape in event of emergency, and to prevent unauthorized entrance, such doors must normally be kept locked. Also, to prevent tampering with the locks on such doors, it has been proposed to equip such locks with an audible alarm means which is actuated whenever the lock is released by the emergency unlocking means.

Heretofore, the locks in which such alarm means has been incorporated have been so arranged that the resetting of the alarm means required the employment of a locksmith to dismantle the lock for that purpose.

Also, it has been common practice in the structure of locks for commercial buildings and the like to provide a so-called deadlocking means to prevent the retraction of the lock bolt by means exterior of the lock case, but

such devices have been inefiective if the full entry of the bolt were prevented by the placing of some obstruction in the bolt receiving opening in the strike plate on the door frame. This deficiencyexists on many locks other than emergency release types of locks and certain phases of the present invention are directed to improvements in deadlocking means which are applicable to both emergency release and other types of locks.

With the foregoing considerations in mind, it is an object of the present invention to provide an emergency or panic lock including an alarm means which is actuated upon emergency release of the lock and which is so con- :structed and arranged as to be capable of being rendered accessible for resetting by key operated means.

Another object of the invention is to provide a lock in which the locking bolt may be deadlocked in any one of a plurality of forward positions.

-A further object of the invention is to provide a panic lock in which the bolt is provided with dead-locking means operable in a plurality of positions of extension of the bolt into the strike plate.

Still another object of the invention is to provide a lock for doors in which the foregoing objectives are realized in practice, which is simple and sturdy in construction, economical to manufacture, and which is reliable in use.

With the forgoing objects in view, together with such additional objects and advantages as may subsequently appear, the invention resides in the parts and in the construction, combination and arrangement of parts, disclosed by way of example in the following specification describing one mode of execution of the invention; reference being bad to the accompanying drawings which form a part of said specification and in which drawings:

Fig. 1 is a side elevation of a lock embodying the invention viewed as the lock is mounted on the side of a door opening toward the viewer; portions of the lock being broken away to disclosedetails of interior construc- "tion,

ice I Fig. 2 is an enlarged view of the same side of the lock with the cover plates removed to show the mechanism carried by the base of the lock,

Fig. 3 is a longitudinal sectional view taken on the staggered line 33 of Fig. 1; the view being enlarged to the same extent as Fig. 2,

Fig. 4 is a transverse sectional view taken on the line 4-4 of Fig. 1 and enlarged to the same scale as Figs. 2 and 3 and illustrating details of the emergency release means,

Fig. 5 is a fragmentary sectional view taken on the line 5-5 of Fig. 3 showing details of the key retained cover means,

Fig. 6 is a perspective view of the bolt dead-locking element, I

Fig. 7 is a further enlarged, partially sectional fragmentary view showing details of the interconnection between the latch bolt and the operating means therefor,

Fig. 8 is a view similar to Fig. 2 but showing the parts as positioned upon emergency release retraction of the bolt,

Fig. 9 is a view similar to Fig. 2 but showing the positions of the parts incident to retraction of the bolt by the key actuated lock, and

Fig. 10 is a view similar to Fig. 2 but showing the positions of the parts when the bolt is only partially'projected into the strike plate opening.

Referring to the drawings, the illustrated embodiment of the invention includes a case structure comprising a base plate lit and a cover means 12 including sections 12a and 12b enclosing the working parts of the lock and secured to the base plate 10. The cover section 12b is secured to the base 10 by screws 95a passing through the base and threadedly engaging lugs 95b on the adjacent surface of the cover section 12b (see Fig. 1). The means for attaching andremoving the cover section 12a will be later described in detail.

Guided for reciprocation by the parallel guide lugs '14, 14 on the base plate and by a closely fitting opening in the end wall 77 of the cover plate 12b is the keeper or latching element 16 hereinafter referred to as the bolt. The opposite sides of the bolt 16 are provided with par= allel rectangular slots 28, 28 extending forwardly from the inner end of the bolt and terminating at a transverse bore 3% extending between the outer ends of the slots. The slots optionally receive a shank portion 24 of a rack element carrying a stud 26 fitting the bore 30 (see Fig. 7) thus permitting the bolt to be assembled in the position shown or with the inclined face thereof reversed to suit individual doors. The rack is guided for reciprocation with the bolt both by the guiding afforded by the guides for the bolt and by a guide member 18 carried by the base 10 and enclosing the rack. The rack and bolt are biased for movement forwardly by a tension spring 2tlc having one end thereof attached to an anchor post 2% carried by the base 143 and having the opposite end thereof attached to a post 29a carried by the rack 20.

Rearwardly of the guide 13 the rack Ztl carries a laterally extending pin 31 which extends into an elongated slot 40 formed in one end of a link 39 which link at its other end is pivotally attached at 36 to the side of a cam element 33 pivctally securedby a screw 32 to a stud projecting outwardly from the base it). The cam element 33 is biased for movement in a clockwise direction as viewed in Fig. 2 by a tension spring 37 one end of which is attached to a tongue projecting laterally from the side of the cam member and the other end of which is anchored to the base it) by a screw 3%.

The carn element is normally held in the retracted position shownv in Fig. 2 by a spring latch element generally designated as 41 and comprising a base run 42 secured to the base plate 10 by a screw 43 passing therethrough and threadedly engaging the base 10, a locking tang 45 engaging a hole 46 in the base plate 10 serving to hold the latch element from rotation about the screw 43, a laterally extending run 41a disposed for engagement by the latch releasing means presently to be described, and a terminal laterally extending run 44 normally projecting through a slot 34 in the cam member 33.

Pivotally mounted on the base plate 10 by a screw 47 disposed below the path described by the outer edge of the cam element 33 in its movement about the screw 32, as viewed in Fig. 3, is a rack holding and releasing latch element 43 including a cam follower arm 49 cooperating with the cam element 33 in a manner presently to be described, a pawl tooth 51 engaging the teeth 'of the rack 20, and a downwardly and thence forwardly extending arm portion 52 which cooperates with other portions of the lock assembly for purposes and in manners which will be later described in detail. For the present description of the panic release of the lock, it is sufficient to point out that the latch member 48 is yieldingly swung about its pivotal mounting so as to hold the pawl in engagement with the space between two teeth of the rack 2t} by a leaf spring 66 pivotally mounted to the base plate ill) at 65 and extending thence past the rear end of the deadlocking plunger 61 and thence in a forwardly extending run 67 below the free end of the latch member arm 52. The dead-locking plunger 61 comprises a round bar guided in guides 62, 62 carried by the base plate 10 and between guides 60, 60 also carried by the base plate 10 and projects through an opening in the end wall 77 of the cover member 12b where it terminates in a beveled end 61a arranged to engage the strike plate S on the door frame at substantially the same time as the strike plate is engaged by the bolt 16 (see Fig. 3) and a compression spring 63 surrounding the plunger 61 and reacting b tween the rearmost guide 62 and an abutment comprising a pin 64 and washer 64a carried by the plunger 61 biases the plunger for movement toward the strike plate. When the door is closed and the plunger is moved into the rearmost position, the spring 66 will be imposing greater pressure against the arm 52 of the latch element 48 as best shown in Fig. 8.

At its rear end, the base plate carries an alarm mechanism generally designated as 70 and comprising a base 72 supporting a bell 73 and containing a spring biased striker mechanism which is wound by turning the bell portion 73 and which is held in releasable wound position by latching means including a trigger element 71 disposed in the path of movement of the cam element 33. A tension spring 68 having one end anchored to the base plate 10 at 69 and the other end thereof connected to the latch member 48 provides a counter bias to the latch member opposing the bias imposed by the spring 66. The cam member 33 has a cam face 50a radially disposed with respect to the axis of movement of the cam member and said cam face terminates at one end in a rounded corner 50 slightly overhanging the follower arm 49.

The cover member 12a includes a front wall 82, a side wall 94 extending around the alarm bell mechanism and along the base plate to the juncture with the cover member 12b and an end wall 91 disposed in close adjacency to the rear wall 80 of the cover member 12b as best shown in Figs. 1 and 3. The cover wall 94 at the extreme rear end thereof is provided with a forwardly projecting lug element 93 which engages an opening in a lug 95 projecting outwardly from the base plate 10. Mounted in the wall 77 of the cover member 12b is a key operated lock mechanism 78 including a rotatable extension journalled in the opening 81 in the wall 80 thereof; said extension terminating in a hook element 79 movable by means of a key inserted in said lock mechanism between a horizontal position shown in full lines in Fig. and a position at right angles thereto in which position it is in alignment with an elongated slot 93a in the end wall 91 of the cover member 12a. The hook element projects through the opening 93a and when in the position shown in Fig. 5, it prevents removal of the cover element 12a from the base plate. When the hook is turned into alignment with the opening 93a, the cover element 12a can be moved to the left as viewed in Fig. 3 until the lug 93 is disengaged from the lug 95 after which the cover may be removed from the base plate.

The panic lock release means is carried by the cove. section 12a and comprises a lever 88 having one end thereof disposed between a pair of inwardly projecting cars 85' and 86 carrying a pivot pin 87 on which the end of the lever 88 is pivotally mounted. The lever 88 extends closely adjacent to the inner face of the cover 12a from its fulcrum point on the pin 87 across an opening 83 in the wall 82 and carries a strike disk 34 closely fitting the opening 83. The lever 88 terminates in an inwardly disposed end portion 89 directly over the run 41a of the latch member 41 and normally is held out of contact therewith by a shear pin 90 formed of soft wood or material of equivalent frangibility and seated in holes 90a and 9% formed respectively in the car 85 and the lever 88 adjacent to the pivot pin 87 and'disposed to be in alignment when the lever is retracted from contact with the latch 41 and the disc 84 is substantially flush with the outer surface of the cover 12a. The shear pin is of sufficient strength to resist accidental pressures against the disc and when it becomes necessary to eifect emergency release of the lock a sharp blow on the disc 84 will shear the pin 90 and cause the free end of the lever to contact the latch member 41 and remove the terminal end 44 thereof from the slot 34 in the cam member 33, whereupon the spring 37 will swing the cam member about the screw 32 and the rounded corner 50 of the cam member will engage the follower arm 49 of the latch member 48 moving the latch member 43 in a clockwise direction as viewed in Fig. 2 against the force exerted by the spring 66 sufficiently to disengage the pawl 51 from the rack teeth; the slot 40 in the link 39 having sufficient lost motion allowance to permit such action. Continued movement of the cam member 33 will cause the link 39 through engagement with the pin 31 to retract the bolt and permit opening of the door, and the final extent of released movement of the cam member 33 will cause the side edge thereof to strike the trigger element 71 with resultant release of the alarm mechanism. In this connection, it is to be noted that the emergency release mechanism is completely concealed beneath the removable cover 12a and that the bolt is retained in retracted position until the cover plate is removed and the latching means is manually reset with a new shear pin inserted to hold the lever 88 in retracted position. After the bolt retracting means has been restored to latched position, the alarm mechanism is rewound by turning the bell portion. Alarm mechanisms of this character are available on the market and detailed description of the interior mechanism is not deemed necessary. Instructions for the operation of the above described emergency release may be cast or otherwise carried by the cover 12:; or they may be carried by a plate 96 inserted in the outer face of the cover as shown in Figs. 1 and 3.

Attention is also directed to the multiple position deadlocking action of the pawl 51 carried by the latch member 48 in preventing retraction of the bolt 16 by force applied to the outwardly projecting end of the bolt. It will be noted in Fig. 2 that the position of the pivot screw 47 is below the plane of engagement of the pawl with the rack. Thus, any forward movement of the bolt and rack will tend to swing the latch in a clockwise direction as each tooth passes the pawl, but any attempt to move the bolt rearwardly will tend to move the pawl upwardly into the space between the teeth engaged by the pawl and thus prevent such movement of the bolt and rack. In the event that the bolt is prevented from completely entering the opening in the strike plate as, for example, by an intentionally inserted obstruction in the strike plate, the

assess? the bias applied to the latch member by the spring 66 in opposition to the opposite bias applied by the light spring 68 which tends constantly to move the latch member in the opposite direction when not opposed by the spring 67.

The bolt 16 may also be retracted by a key operated means without release of the emergency release means; said key operated means comprising a cylinder loci; means 75 carried by the front wall 74 of the cover member 12b and within the case of the lock terminating in a rotatable tongue element 76 engaging a slot 56 in the end of a shaft 55 axially aligned with the axis of rotation of the tongue element 76 and having its other end journaled in the base plate approximately midway between the opposed faces of the rack 20 and the arm 52 of the latch member 48. Fixed to the shaft 52* is a mutilated gear 54 having a series of gear teeth 57 adapted to mesh with the teeth of the rack 20 and also having a substantially diametrically opposite cam element 58 normally engaging a shoulder 53 on the edge surface of the latch member 48 and being adapted upon rotation of the gear by the lock means to ride over said shoulder and displace the latch member and pawl from locking engagement with the rack teeth before the gear teeth 57 engage the teeth of the rack. The slot in the link 39 permits the independent movement of the bolt and rack by the key operated means.

,Incident to further rotation of the gear by the lock means 75 and resultant retraction of the bolt, the cam element rides along the radially curved edge surface 53a of the latch member holding the pawl out of contact with the rack teeth. Upon reverse movement of the lock means,

the bolt will be moved out of the lock and finally the cam element will ride back over the shoulder 53 allowing the latch member to return the pawl 51 into locking engagement with the rack teeth. In this connection it is to be noted that when the bolt is retracted by the key means above described, upon release of the key While in the lock, the spring 200 will immediately move the bolt forward with resultant release of the dead-locking pawl into locking engagement with the rack and consequent prevention of retraction of the bolt except by the said key means or by the use of the panic or emergency release .means previously described. Additionally, the locking means 75 is such as to prevent entry or removal of a key except in the position shown in Fig. 2 at which time the bolt is projected out of the end of the lock. This is convenient in that when the door is opened by means of a key as may be necessary, for example, as an incident to a watchmans rounds, the key can be removed and the door closed with resultant dead-locking of the bolt by the plunger in the manner previously described.

While in the foregoing specification there has been disclosed one mode of execution of the invention, the invention is not to be deemed to be limited by the said disclosure, and it is to be understood that the invention includes as well all such modifications in the parts and in the construction, combination and arrangement of parts as shall come within the purview of the appended claims.

I claim:

1. in an emergency exit door lock, a case comprising a base and a removable cover means, a trigger released alarm means mounted on said base and including a trigger element, a latch bolt means mounted for reciprocatory movement on said base and through an end wall of said -cover means for lockingengagement and disengagement with a strike plate opening, spring means normally urging ,saidlatch bolt means into said locking engagement, dead locking means comprising a plurality of teeth on-said latch bolt means disposed in spaced relation in a line parallel to the path of movement of said latch bolt means and a spring biased pawl component normally engaging said teeth and constructed and arranged to permit the movement of said bolt means into said locking engagement to any one of a plurality of extents of movement defined by said teeth and to prevent the retraction of said bolt from said locking engagement by force applied to the outwardly projected end of said bolt, spring biased emergency bolt retracting means operatively connected to said bolt means, a spring latch normally restraining the movement of said emergency bolt retracting means, means projecting through said cover means manually operable to disengage said spring latch, and devices operated by said emergency bolt retracting means upon release of said spring latch effective to disengage said pawl component of said dead locking means from the one of said teeth engaged thereby as a prior incident to the retract-ion of said bolt means by said emergency bolt retraction means and said emergency bolt retracting means thereafter being effective to enagage said trigger element with resultant release of said alarm means.

2. In an emergency exit door lock mechanism, a case comprising a base and a removable cover, a trigger released alarm means mounted on said base and including a trigger element disposed in the path of movement of a moving part of said lock mechanism, a bolt means mounted in said case for reciprocatory movement through an end wall of said case into and out of locking engagement with a strike plate opening; dead locking means for said bolt means including a member within said case extending parallel to the path of movement of said bolt means and having a plurality of transversely disposed teeth on one face thereof and a spring biased pawl component normally engaging said teeth and eifective to permit movement of said bolt means into said locking engagement and to prevent retraction of said bolt means from said locking engagement by force applied to the outwardly projecting end of said bolt, spring biased emergency bolt retracting means operatively connected to said bolt means, latch means normally holding said emergency bolt retractmg means inoperative, and means mounted internally of said case and operable externally of said case to release said latch means; said emergency bolt retracting means including a movable member effective upon release of said latch means successively to disengage said pawl component of said dead locking means and to engage said trigger element with the resultant release of said bolt means upon retraction of said bolt for retraction and the activation of said alarm means.

3. In an emergency exit door lock, a case comprising a base and removable cover, a bolt means mounted within said case for reciprocatory movement through an end wall of said case into locking engagement with a strike plate opening to any one of a plurality of extents; said bolt mean including a member within said case movable in a line parallel to the path of movement of said bolt means and having a series of transversely disposed teeth extending in a line parallel to the path of movement of said bolt means, a spring biased pawl element normally engaging one of said teeth defining the outward extent of movement of said bolt; said engagement being effective to resist retraction of said bolt means from any one of said plurality of extents of movement of said bolt means in said locking engagement, by force exerted on the outwardly projecting end of said bolt, spring biased emergency bolt retracting means operatively connected to said bolt means, a manually operable latch means normally holding said emergency bolt retracting means in inoperative position, and pawl disengaging means carried by said emergency bolt retracting means effective upon release of saidemergency bolt retracting means by said latch means to disengage s-aidpawl element from said teeth prior to the retraction ;f said boltmeans by said emergency bolt retracting means.

1 4. In'an emergency exit door look, a case comprising a base and a removable cover mounted thereon and housing a lock mechanism and an independently powered, trigger released alarm mechanism; said lock mechanism including a bolt component including a spring biased bolt mechanism normally urged into locking engagement with a strike plate opening and spring biased bolt dead locking means normally effective to prevent retraction of said bolt from a strike plate opening by force applied externally of said case, spring biased, emergency bolt retracting means 'operatively connected to said bolt mechanism and engageable with said alarm mechanism and said bolt dead locking means, latch means normally holding said emergency bolt retracting means from operation, and manually open able means carried by said removable cover effective to release said latch means with resultant release of said spring biased, emergency bolt retracting means to effect in sequence the disengagement of said bolt dead locking means from said bolt, the retraction of said bolt component from the strike plate opening, and the activation of said alarm mechanism.

5. In an emergency exit door lock, a case comprising a base, a removable cover, and a key actuated lock means for releasing said cover from and securing said cover to said base, lock mechanism Within said case including a bolt and spring biased means normally urging said bolt outwardly of said case and into locking engagement with a strike plate opening, a latch within said case, mechanism within said case restrained by said latch and connected to said bolt effective upon release from said latch to retract said bolt, and latch releasing means mounted on said cover and including a manually engageable member extending through an opening in said case operable to disengage said latch from said restrained mechanism; said cover upon removal from said base affording access for reengaging said latch with said mechanism restrained by said latch.

6. A lock as claimed in claim 5 in which the latch releasing means includes a latch contacting element normally held out of engagement with the latch by a replaceable, frangible element.

7. In a door lock, 2. case comprising a base and a cover carried by said base, lock mechanism Within said case including a bolt mechanism movable out of said case into locking engagement with a strike plate opening, a spring effective to urge said bolt mechanism into said lockingengagement, a member having a plurality of teeth connected to and movable with said bolt mechanism, a pivotally mounted pawl engageable with the teeth of said member and effective during engagement therewith to permit movement of said bolt mechanism only in the direction of said locking engagement, a reciprocable member normally projecting from said case for yielding engagement with the strike plate, and a spring engaged by said reciprocab'le member effective upon engagement by said member with the strike plate to swing said pawl into engagement with said toothed member.

8. An emergency exit door lock comprising a base, a housing covering said base and including a first portion having an end Wall and a second portion detachably secured to said base, a bolt mechanism including a bolt slidably supported on said base and spring means normally effective to maintain said bolt projected through an opening in said end wall for engagement with a strike plate opening, a link operatively coupled to said bolt for retracting said bolt, a spring biased element connected to said link and normally effective to cause said link to retract said bolt against the resistance offered by said spring means, a spring latch engaging and holding said spring biased element in a position allowing said bolt to be projected through said opening, and latch releasing means carried on the inner face of said second portion of said housing and including a strike disc disposed for manual contact in an opening in'said second portion of said housing and a lever operated by manual engagement of and resultant movement of said strike disc into said opening in said second portion of said housing effective by said movement to disengage said latch from said spring biased element with resultant retraction of said bolt by the action of the released, spring biased element.

9. The combination with a lock as claimed in claim 8 of a trigger released alarm means and means for releasing said alarm means by movement of said spring biased element upon release thereof by said latch.

10. A lock as claimed in claim 8 in which said spring biased element comprises a plate mounted for oscillation on said base and to which one end of said link is pivotally secured, and in which when said spring biased element is engaged by said latch, said link is disposed parallel to the line of reciprocation of said bolt; the opposite end of said link having a longitudinally extending slot in which a pin carried by said bolt extends; said engagement between said pin and said slot affording freedom of reciprocatory movement of said bolt when said spring biased element is restrained by said latch.

11. A lock as claimed in claim 8 in which said bolt carries a rack and in which said base carries a gear adapted to mesh with said rack,'and a key operated lock means operatively connected to said gear effective to effect retraction of said bolt by rotating said gear.

12. A lock as claimed in claim 11 including a dead locking means effective to prevent retraction of said bolt and devices effective upon initial turning of said gear by said key operated lock means effective to disable said dead locking means.

13. An emergency exit door lock comprising a base, a two part housing mounted on said base and enclosing a reciprocable bolt and bolt operating mechanism therewithin; said bolt operating mechanism including a spring normally yieldingly projecting said bolt out of a wall of said housing for engagement with a strike plate opening, spring biased means normally effective to retract said bolt against the bias of said bolt projecting spring, latch means engaging said spring biased, bolt retracting means and effective by such engagement to hold said bolt retracting means restrained against bolt retracting action, a key actuated means on one of said housing parts operable to effect retraction of said bolt independently of said spring biased means, manually operable latch disabling means carried by the other of said housing parts, and a second key operated lock means detachably securing said second housing part to said base.

14. A lock as claimed in claim 13 in which said first housing part includes a wall extending perpendicular to said base and through which said bolt is projected and in which said second key actuated lock means is carried by said first housing part and includes a key receiving opening in said wall.

15. A lock as claimed in claim 14 in which said second, key actuated locking means includes a key receiving barrel having the key receiving end thereof mounted in the wall of said first housing part through which the bolt projects; said barrel thence extending within said first housing part parallel to the bolt and terminating in a hook element extending through an elongated opening formed in a transversely extending flange portion of said second housing part; said hook being disposed transversely to the length of said opening when in locking position.

16. In a door lock, 21 case comprising a base and a cover removably mounted thereon, lock mechanism Within said case including a bolt movable through a wall of said case into and out of locking engagement with a strike plate opening, spring means normally moving said bolt into said locking engagement, spring biased means including a latch releasable from the exterior of said case effective to retract said bolt in opposition to the resistance of saidspring means, dead locking means effective to prevent retraction of said bolt by force applied to said bolt externally of said case at any one of a plurality of extents of movement of said bolt into the strike plate opening, a strike plate engaging device carried by said lock and means actuated thereby upon engagement of said device with a strike plate to render said dead locking devices effective to prevent retraction of said bolt by force applied to the portion of said bolt within the strike plate opening, said spring biased, bolt retracting means including devices effective to disable said dead locking means as a prior incident to bolt retraction by said spring biased means.

17. An emergency exit door lock comprising a base, a housing covering the base and having a front wall and side walls, a bolt mounted on the base in the housing for reciprocable movement through a side wall at one end of the base, a reciprocable link connected with said bolt, spring means operatively connected with said link and urging movement of the bolt toward unlocking position, a movable latch element operatively connected with the link and holding the latter against movement under the urging of said spring means, a lever pivotally mounted within the housing upon said front wall, a means carried by the lever in position to engage and move the latch element to a position to release the link when the 10 lever is swung on its pivot in one direction, frangible means holding said lever out of engagement with said latch element, said housing front Wall having an opening therein, and a manually engageable disc disposed within said opening and carried by said lever.

18. A lock as claimed in claim 17 in which said frangible means comprises a shear pin supported by said housing and extending transversely of the path of movement of said lever when moved to latch releasing position elfective to restrain said lever from accidental movement in said path and resultant unintentional release of said latch element.

References Cited in the file of this patent UNITED STATES PATENTS 426,389 Lacey Apr. 22, 1890 756,839 Edmonds Apr. 12, 1904 777,271 Alrutz et a1 Dec. 13, 1904 1,452,471 Kline Apr. 17, 1923 2,535,126 Flowers et a1. Dec. 26, 1950 2,607,313 Eads Aug. 10, 1952 FOREIGN PATENTS 88 Great Britain Jan. 1, 1910 790,332 France Sept. 2, 1935

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