US3561395A

US3561395A - Burglar alarm for vending machine

Info

Publication number: US3561395A
Application number: US783352A
Authority: US
Inventors: Edwin John Piersma; Lloyd David Herring
Original assignee: Rowe International Inc
Current assignee: Rowe International Inc
Priority date: 1968-12-12
Filing date: 1968-12-12
Publication date: 1971-02-09
Anticipated expiration: 1988-02-09
Also published as: DE1960835A1

Abstract

A burglar alarm for vending machines comprising a reinforced door assembly to protect the coin collection box, a key operated tumbler lock for securing the door assembly in flush position upon the cabinet of vending machine, linkage means connected to a trigger mechanism for actuating normally disabled sound producing device, and sensing levers for detecting the application of an unauthorized force to the tumbler lock to thereby move the linkage means to release trigger and actuate the sound producing device. After sound producing device has been actuated to alert persons in the vicinity of the machine that a burglary attempt is being made, authorized personnel can open the vending machine cabinet and manually reset the spring-loaded trigger to thereby disable sound producing device.

Description

United States Patent [72] Inventors EdwinJohnPiersma Grand Rapids; Lloyd David Herring. Jenison, Mich. [2| Appl. No. 783,352 [22] Filed Dec. 12, 1968 [45] Patented Feb. 9, 1971 [73] Assignee Rowe International, Inc.

Whippany, NJ. a corporation of Delaware [54] ,BURGLAR ALARM FOR VENDING MACHINE 9 Claims, 9 Drawing Figs.

[52] US. Cl 116/86, 116/8, 116/1 12; 222/39; 340/406 [51] Int. Cl G08h 13/08 [50] Field of Sarch 116/6, 8, 9,

75, 80, 81, 85, 86, 100, 112; 70/77, 78, 91, 92, 432, 440; 340/404, 405, 406, 297; 22l/(lnquired);

Primary Examiner-Louis J. Capozi Attorney-Shenier & O'Connor ABSTRACT: A burglar alarm for vending machines comprising a reinforced door assembly to protect the coin collection box, a key operated tumbler lock for securing the door assembly in flush position upon the cabinet of vending machine, linkage means connected to a trigger mechanism for actuating normally disabled sound producing device, and sensing levers for detecting the application of an unauthorized force to the tumbler lock to thereby move the linkage means to release trigger and actuate the sound producing device. After sound producing device has been actuated to alert persons in the vicinity of the machine that a burglary attempt is being made, authorized personnel can open the vending machine cabinet and manually reset the spring-loaded trigger to thereby disable sound producing device.

FD n0 PATENTEI] FEB 9 I971 SHEET 1 BF 3 INVENTORS EDWIN JOHN P|ERSMA&

I LLOYD DAVID HERRING TTORNEYS PATENTED FEB 9 |97l sum 2 OF 3 m m m a N A G E M m M R R E m P H m m V O m J m m m w 0 D L E L 6 r. 6 9(X 6 6 M 4- 4 8 V BY w ffmw ATTORNEYS PATENIED res 9|9r| sum 3 BF 3 INVENTORS EDWIN JOHN PIERSMA a LLOYD. DAVID HERRING BY 9Wwnj ATTOR NEYS BURGLAR ALARM FOR VENDING MACHINE BACKGROUND OF THE INVENTION 1. Field of the Invention The instant invention relates generally to burglar alarms and similar audible warning devices for use in conjunction with vending machines, coin-operated jukeboxes, etc., and more particularly to a self-contained, mechanically operated burglar alarm wherein the audible warning signal is created by the rapid rushing of pressurized gas through a sounding horn, sonic whistle, or the like.

2. Description of the Prior Art The problem of pilferage of merchandise and money from vending machines, jukeboxes, telephone coinboxes, and the like, represents a significant financial problem to the owners and operators of such machines. In addition to the loss of profits, the cabinet containing the merchandise and money is frequently damaged during the burglary attempt; thus the machine must be repaired, and the financial loss to the machine owners and operators is compounded.

Numerous attempts have been made, with limited success, to defeat the pilferage problem. One typical solution has been to provide an electrically powered burglar alarm inoperative association with the key-operated locking means for the coin collection box of the vending machine. When the electrically powered burglar alarm is triggered by the application of force to the coin collection box, it completes a circuit and thereby sets off an audible alarm in the vicinity of the vending machine or relays a signal silently to a remote location, such as a police station, or performs both functions.

However, electrically powered alarm systems require the services of an expert technician to install and periodically service same. The installation and maintenance costs are substantial when compared to the amount of money that can be collected in a given time period by a small vending machine, such as a wall mounted jukebox, candy vending machine, etc. Additionally, many of the electrically powered burglar alarms can be disabled by severing the power lines leading from the source of electrical power into the vending machine cabinet.

Another typical solution to the pilferage problem has been to provide a mechanical alarm system characterized by an auxiliary or secondary locking means, situated at a location inaccessible from the exterior of the cabinet, for coaction with the conventional key-operated locking mechanism. Such secondary locking mechanism, which simultaneously sets off a self-contained alarm and relocks the door of the cabinet, is actuated after the key operated lock is disabled by force or other unauthorized methods and the door to the cash box is opened a crack. US. Pat. No. 3,185,127, granted to Ronald K. Chedister, is deemed to be representative of the variety of burglar alarm systems utilizing secondary locking mechanisms to actuate a self-contained, mechanically operated horn.

Although a mechanically operated burglar alarm is usually easier and cheaper to install and maintain in operative condition than the above described electrically operated burglar alarm system, such mechanically operated alarm systems suffer from other material shortcomings. To illustrate, the secondary locking mechanism disclosed in the Chedister patent permits the door to the cabinet to be opened a crack, in the order of a sixteenth of an inch or more, before the horn is sounded. This crack may be of sufficient magnitude to enable a burglar to insert the end of a manual tool, such as a screwdriver or erowbar, and exert sufficient leverage to force the door to the cabinet wide open. Alternatively, the burglar may insert a thin wire implement through the crack and skillfully pick the secondary locking mechanism, thus providing free access to the contents of the vending machine.

SUMMARY Thus, with the deficiencies of the known burglar alarms for vending machines enumerated above in mind, the instant invention contemplates a mechanically operated, self-contained inexpensive alarm system that is fully compatible with existing machines. Such alarm comprises a minimum number of components of simplified design that insure foolproof operation of the alarm system whenever unauthorized entry into a locked enclosure or vending machine housing is sought through force or other methods. These objectives are achieved in the instant invention by providing a pair of sensing levers that are operatively associated with the latch of the conventional key operated tumbler lock. These sensing levers, which are biased into engagement with opposite faces of the latch, detect the unauthorized application of force to the door enclosing the coin collection box, and immediately move an actuating rod which releases a spring loaded valve trigger from a retainer member. The valve trigger depresses a button for the normally closed valve assembly mounted atop a pressurized container and releases the contents of the container through a sounding horn, sonic whistle, etc. The long-lived, intense audible alarm may well frighten away burglars and possibly aid in apprehending same.

The instant invention also contemplates stop means that define a equilibrium position for the sensing levers, such position being maintained whenever the key-operated locking mechanism is opened by authorized personnel to gain access to the interior of the machine housing.

Furthermore, the instant invention contemplates an improved retainer element for normally holding the valve trigger for the pressurized container in an inoperative condition. The retainer element is manually reset after the horn has been sounded, either to frighten burglars away or for periodic testing purposes.

Yet additionally the instant invention provides a door of reinforced design that is easily secured to a door frame housing in the vicinity of the coin collection box; such door fits flush with the machine housing and thus minimizes the opportunity to physically pry same free without actuating the burglar alarm disposed within the machine housing.

Other objects and advantages of the instant invention will become apparent in light of the following description of the invention when construed in connection with the accompanying sheets of drawings.

DESCRIPTION OF THE DRAWINGS FIG. I is an exploded perspective view of the lower portion of the rear section of a vending machine housing or similar enclosure;

FIG. 2 is an exploded perspective view, on an enlarged scale, of the reinforced door and key-operated locking mechanism for the machine housing or enclosure;

FIG. 3 is a rear elevational view of the reinforced door and the locking mechanism therefor secured to the vending machine housing, such view further depicting the sound producing device and the sensing levers constructed in accordance with the instant invention for actuating same;

FIG. 4 is a vertical cross-sectional view of a fragment of the lower portion of the reinforced door and the vending machine housing, such view being taken along line 4-4 in FIG. 3 and in the direction indicated;

FIG. 5 is a top plan view of the reinforced door, the sound producing device and the sensing levers operatively associated with the latch of the key-operated locking means for actuating the sound producing device;

FIG. 6 is a perspective view, on an enlarged scale, of the valve trigger mechanism for releasing the contents of a pressurized container into the sound producing device, the trigger being depicted in normal, inoperative position;

FIG. 7 is a top plan view of the sensing levers and trigger mechanism for actuating the sound producing device, the levers and the trigger mechanism being shown in operative position;

FIG. 8 is a side elevational view of the valve trigger for operating a gas container to pressurize the burglar alarm; and

FIG. 9,is a top plan view of the trigger mechanism for actuating the burglar alarm, such mechanism being depicted in its normal, inoperative position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in greater detail to the drawings in which similar reference numerals refer to similar parts, FIG. I depicts the lower,,rear section of a vending machine housing, indicated generally by reference character 10. The interior of the housing is visible for closure plate 12 has been removed for the sake of clarity, and one can see a rectangular aperture 14 in the side of the housing defined by an inwardly extending ledge 16.

As indicated by the dotted line, a cashbox enclosure 18, which is open only at one side, is secured within housing with its interior surfaces abutting ledge 16. A slot is located in the upper surface of box 18 so that coins deposited in a coin chute (not shown) can pass into the interior of the box and be collected within coin collection bag 22. A reinforced door assembly indicated generally by reference numeral 24, is secured to the exterior of housing 10 via keeper plate 26 in a manner that precludes unauthorized removal or tampering with the contents of coin collection bag 22.

FIGS. 2 and 4 show the structural details of the reinforced door assembly 24 and the manner in which the door is secured by keeper plate 26 to ledge 16 so as to be flush with housing '10. Door assembly 24, which may be fabricated from metal or executed in plastic, has an exterior face broken only by the outwardly opening end of guide 28. The door is reinforced by a matrixlike pattern of horizontal and vertical .

beams

30 and 32, as shown in FIGS. 2 and 3. A plurality of spaced apertures 34 are formed in keeper plate 26 to enable a similar plurality of screws 36 to pass therethrough into threaded guides 38 on the inner face of the door. Thus, as seen in FIG. 4, when screws 36 are tightened, keeper plate 26 is secured to ledge 16 and door assembly 24 fully conceals aperture 14 and the contents of coin collection bag 22.

Returning again to FIG. 2, door 24 further includes a latch plate 40 with a horizontally extending offset leg 42 that has a slot 44 formed therein. The plate is secured to door assembly 24 by screws 46 that pass through apertures in the plate and are threadedly engaged within guides 48 located adjacent to tubular guide 28.

A circular aperture is formed in the center of latch plate 40 to enable a key operated tumbler lock, indicated generally by reference character 50, to pass therethrough and thus secure the door assembly 24 to ledge 16.

As will become apparent from the ensuing discussion, part of the tumbler lock 50 of conventional design is situated on the exterior surface of door assembly 24, while the remaining part of the tumbler lock is situated on the interior surface thereof for securement purposes. The chain line extending through tubular guide 28 indicates the manner and spatial relationship in which the component parts of the tumbler lock 50 are secured together.

Lock 50 includes a key slot (not shown) which receives key 52 therein, and a circular sleeve 54 which aligns the lock within the outwardly opening end of guide 28. The barrel 56 of the lock is threaded along its peripheral length, as seen in FIG. 2, and extends through guide 28 and the central aperture in plate 40. A nut 58 is rotated along the barrel until it abuts the inwardly opening end of guide 28 and thereby secures lock 50 in operative position.

Barrel 56 has a recess 60 at its innermost end and a screw, rivet or similar securement element 62 is pressed therein through an aperture 64 in latch 66 so that latch 66 pivots in response to the turning movement of key 52 within the key slot. Thus, when the key 52 is vertically oriented and inserted into the key slot (not shown), then latch 66 will be vertically oriented and extend through slot 44 in the offset leg 42 of latch plate 40. Such vertical orientation of the latch defines the locked position for tumbler lock 50.

FIG. 3 depicts the reinforced door assembly 24, the tumbler locking mechanism therefor including latch-66, the sensing lever mechanism operatively associated with the latch 66 of the tumbler locking mechanism, and the sound producing device actuated by the sensing levers whenever unauthorized personnel attempts to force open the tumbler locking mechanism. The sensing lever mechanism is indicated generally by reference numeral 68, and the sound producing device or burglar alarm is indicated generally by reference numeral 69. The view in FIG. 3 is taken at a position within cabinet 10 in the vicinity of cashbox I8 and looking outwardly therefrom. FIG. 5, which is a top plan view of the same mechanisms, should be construed in conjunction with FIG. 3 to more .fully appreciate the structural configuration and operational characteristics of these mechanisms.

Thus, it will be appreciated that sensing lever mechanism 68 comprises an L-shaped mounting

plate

70, 72 that is permanently affixed to the interior wall of cabinet 10 by screws 74. The horizontally offset portion 72 of the plate 70 extends parallel to the offset portion 42 of plate 40. An aperture or slot 76 is formed in offset portion 72 and is aligned with aperture 44 in offset portion 42 so that the upper end of latch 66 of tumbler assembly extends therethrough and can be freely pivoted through these slots in response to the rotational movement of key 52.

Sensing lever mechanism 68 further comprises a first sensing lever 78, a second sensing lever 80, and a link 82 interconnecting the two sensing levers. The midpoint of lever 78 is secured to plate 72 by post 84 for pivotable motion relative thereto. One end of lever 78 bears against the inner face of the upper end of latch 66 while the opposite end of the lever is secured to link 82 by pin 85.

Second sensing lever is secured to plate 72 by post 86 for pivotable motion relative thereto. One end of lever 80 bears against the outer face of the upper end of latch 66 while the opposite end is secured to link 82 by one end of actuating rod 88. Rod 88 is thus directly responsive to the pivotable movement of lever 80, and indirectly responsive to the pivotable movement of lever 78 .via link 82.

A coil spring 90 has one end secured to link 82 adjacent to red 88 and has its opposite end secured to upstruck ear 92 on plate 72. The normal, unstressed condition of spring 90 is visible in FIG. 5, while the stressed condition of spring 90 is visible in FIG. 7. A stop 94 is located adjacent to sensing lever 80 and cooperates with spring 90 to define a nonnal equilibrium condition for the entire sensing lever mechanism 68. A leaf spring 96, with one end secured to screw 74, has its offset portion bear against the upper end of latch 66 and thereby minimize, if not totally eliminate, the play in tumbler lock 50. Such equilibrium c'ondition enables authorized personnel to open tumbler lock 50 by pivoting latch 66 out of contact with

levers

7,8, 80 without actuating the sound producing device.

Actuating rod 88 is an integral part of burglar alarm or sound producing assembly 69 and constitutes the structural link through which the operation of the sensing lever assembly 68 is translated into an audible alarm by sound producing assembly 69. As best shown in FIGS. 3, 5 and 7, rod 88 has its upper end joined to link 82 and second sensing lever 80. Rod 88 slants downwardly at its midsection so that the lower end of the rod can be joined to the midpoint of trigger retainer 98.

Retainer 98, which has an upstruck portion 99, is secured to horizontally extending support by post 102, as shown in FIG. 8, thus permitting the retainer to pivot relative to the support. A deep notch 104 is removed from one side of the retainer and the valve trigger 106 for a pressurized can I08 of freon is normally retained therein. Trigger 106 is generally U- shaped in horizontal cross section and extends downwardly below support I00 by virtue of its groove pin shaft 110 which extends through its upper end and engages the button 114. A coil spring 112 extends between one end of the support and an intermediate segment of the trigger, and serves to spring load the trigger connected to 114 of burglar alarm assembly 69 as shown by FIG. 8. The U-shape of valve trigger I06 fully embraces button 114 to insure foolproof operation.

The flat outer section of the exterior of the U- shaped trigger 106 normally rests against the bottom and one side of notch 104 in retainer 98; the normal condition, in which sound producing assembly isdisabled, is visible in FIGS. 2, 3, 5, 6, 8 and 9 (note the solid lines). When retainer 98 is pivoted about post 102, trigger 106 is released from notch 104 and pivots clockwise about shaft 110 under the urging of spring 112, as indicated by the directional arrow in FlG. 8. Such clockwise motion forces button 114 inwardly and opens the normally closed valve assembly 116 disposed atop the pressurized con-' tainer 108. The opening of the valve assembly permits the contents of container 108 to escape through conduit 118 and thence into horn 120. The horn will then sound a piercing audible warning blast for a period of time to call attention to the attempt to tamper with the cashbox and/or the contents of the machine housing.

When the tampering attempt has been detected and/or thwarted, trigger 106 is manually reset into engagement with notch 104 in retainer 98. The upstruck portion 99 of the retainer retension spring 112 and cocks trigger 106. Such resetting of the trigger enables button 1 14 to return to its normal, undepressed position, thus closing valve assembly 116 and terminating the sounding of horn 120.

SUMMARY 0F OPERATION Referring again to FIG. 1, the sensing lever mechanism 69 is disposed within the interior of the cabinet or housing above the upper surface of aperture 14. Coin collection box enclosure 18 is then secured to housing 10 along ledge 16 so that aperture l4 permits ready access to the interior of the hous- Coin collection bag 22 is then inserted through aperture 14 into enclosure 18 so as to receive coins deposited in a coin chute (not shown) at the front or side of the machine. Keeper plate 26 is then secured to reinforced door assembly 24 by tightening screws 26, as has been shown in FIG. 2, and tumbler lock 50 is inserted through guide 28 and rotated to an inoperative position. Assembly 24 is then positioned within aperture 14 and retained therein in the manner shown in FIG. 4. Tumbler lock 50 is subsequently adjusted to locking position wherein latch 66 extends upwardly through

slots

44 and 76 in

plates

42 and 72, respectively, into operative position with respect to sensing lever mechanism 68, and key 52 is removed from the slot in the tumbler loek. It is noted that door assembly 24 mounts flush with the exterior surface of housing 10 and completely encloses aperture 14.

Referring now to FIGS. 3 and 5, it will be appreciated that leaf spring 96 bears against the upper end of latch 66 and eliminates the play in the latch, thus contributing to the successful operation of the sound producing device or burglar alarm. The first pivotable sensing lever 78 and the second pivotable sensing lever 80 are disposed on opposite sides of latch 66 and normally bear against the opposite faces of the latch. The levers are interconnected by link 82, and the sensing lever mechanism is biased into an equilibrium condition by spring 90 which urges lever 80 in counterclockwise fashion against stop 94. The maintenance of this equilibrium condition is of significance, for it enables authorized personnel to operate the tumbler lock 50 to rotate latch 66 out of contact 'With the sensing levers without setting off the sound producing device or burglar alarm mechanism 69. The opening of the lock enables an attendant to remove door assembly 24, empty the contents of bag 22, replace the bag and relock the door.

The equilibrium condition'for the sensing lever mechanism 69 is structurally and functionally correlated with the normal, or unactuated, condition of the sound producing device or burglar alarm 69. Actuating rod 88 is joined at one end to second sensing lever 80 and link 82 and is joined at its opposite end to pivotable retainer 98. When sensing lever mechanism 69 is in its equilibrium condition, spring biased trigger 106 is held in disabled position within notch 104 in retainer 98 and the horn 120 is silent. This condition is illustrated in FIGS. 5, 6 and 9.

When a force is applied to the door assembly 24. either in a plane perpendicular to same as when delivered by a hammer.

or when a prying action is applied to the door. such as by a screwdriver or crowbar, such force will tend to distort latch 66. This distortion, which may be a physical twisting of the latch or merely a shifting of the latch with respect to the sensing levers, disturbs the equilibrium condition by pivoting

sensing levers

78 or 80, which will shift actuating rod 88 and cause retainer 98 to pivot clockwise about shaft 102. as illustrated in H0. 7. Valve trigger 106 is thus released from notch 104 in retainer 99 and spring 112 pulls the trigger and button 114 to which it is attached with groove pin 110, to open valve 116 as shown in FlG.'8. Pull out of the button opens valve assembly 116 and permits freon or a similar pressurized gas within container 108 to escape therefrom and operate horn 120. The audible warning alarm will continue to sound until the contents of container 108 are exhausted or until authorized personnel open the machine and manually reset valve trigger 106 into notch 104 in retainer 94, thereby enabling button 114 to return to its unactuated position and close valve assembly 116. The upstruck portion 99 of retainer 98 assists in restressing spring 112.

Thus, it is readily apparent from the above described sequence of operation, that sensing lever mechanism 68 will operate sound producing device or burglar alarm 69 before door assembly 24 can be penetrated or pried loose from inwardly extending ledge 16. Accordingly, the instant self-contained, mechanically operated burglar alarm affords maximum protection for vending machines and the like with minimized costsfor the manufacturing, installing and servicing of same.

Since additional modifications may be made to the components of this invention without departing from the scope thereof, such as by substituting a sonic whistle for the horn, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative in nature and not in a limiting sense.

We claim:

1. An enclosure including a door frame defining an aperture 9 in one of the walls of said enclosure; said aperture permitting manual access to the interior of said enclosure; a door assembly secured to said frame; lock means including a pivotally mounted latch for holding said door assembly closed within said frame to prevent unauthorized manual access to the interior of said enclosure; said latch being disposed on the interior of said enclosure to engage said door frame; a normally inoperative, sound-producing device located within said enclosure; operating means connected to said sound-producing device for actuating said device; sensing means operatively associated with said latch for detecting unauthorized movement of said latch; said sensing means including a mounting plate secured to the inner face of said door assembly, a plurality of posts secured to said plate, and a like plurality of levers mounted upon said posts for movement toward opposite faces of said latch; said sensing means being connected to said operating means for actuating said sound-producing device whenever an unauthorized pushing or pulling force is applied to said door to forcibly open same.

2. The combination as defined in claim 1 wherein said sensing means further includes spring means secured to said mounting plate for pivotally urging said levers toward opposite faces of said latch.

3. The combination as defined in claim 1 wherein said mounting plate has a slot therein of sufficient size to permit the latch to be freely pivoted therethrough when access to the interior of said enclosure is authorized.

4. The combination as defined in claim 2 wherein said sensing means further comprises an upstruck ear on said mounting plate, said ear defining an equilibrium position for limiting the movement of said levers toward said latch in response to the urging of said spring.

5. The combination as defined in claim 1 wherein said sensing means further comprises a link interconnecting said plurality of levers, said operating means being connected between said link and said sound producing device whereby movement of said link will actuate the sound producing device.

6, The combination as defined in claim 1 wherein spring means are secured to the interior surface of said door assembly to press against said latch and maintain same in a plane parallel to said interior surface.

7. The combination as defined in claim 1 wherein said operating means comprises an actuating rod and a retainer member, support means secured to the interior of said enclosure for maintaining the'normally disabled sound producing device in fixed position, said retainer member being secured to said support means for motion relative to said sound producing device, and said rod connected between said sensing means and said retainer member whereby movement of said sensing means shifts said retainer member to actuate said sound producing device.

8. The combination as defined in claim 1 wherein said door frame includes an inwardly extending ledge of substantially rectangular configuration'and said door assembly includes a door and a keeper plate securedto. and spacedfrom, the interior surface of said door, and securement means for tightening said keeper plate against said ledge to mount said door flush with the exterior surface of said enclosure.

9. The combination as defined in claim 8 wherein said door assembly further includes a latch plate secured to the interior surface of said door, said latch plate having a slot formed therein. said mounting plate disposed above said latch plate and also having a slot formed therein. a pin securing said latch to said lock means to that said latch can be moved through said slots in response to actuation of said lockmeans.

Claims

1. An enclosure including a door frame defining an aperture in one of the walls of said enclosure; said aperture permitting manual access to the interior of said enclosure; a door assembly secured to said frame; lock means including a pivotally mounted latch for holding said door assembly closed within said frame to prevent unauthorized manual access to the interior of said enclosure; said latch being disposed on the interior of said enclosure to engage said door frame; a normally inoperative, sound-producing device located within said enclosure; operating means connected to said sound-producing device for actuating said device; sensing means operatively associated with said latch for detecting unauthorized movement of said latch; said sensing means including a mounting plate secured to the inner face of said door assembly, a plurality of posts secured to said plate, and a like plurality of levers mounted upon said posts for movement toward opposite faces of said latch; said sensing means being connected to said operating means for actuating said sound-producing device whenever an unauthorized pushing or pulling force is applied to said door to forcibly open same.

6. The combination as defined in claim 1 wherein spring means are secured to the interior surface of said door assembly to press against said latch and maintain same in a plane parallel to said interior surface.

7. The combination as defined in claim 1 wherein said operating means comprises an actuating rod and a retainer member, support means secured to the interior of said enclosure for maintaining the normally disabled sound producing device in fixed position, said retainer member being secured to said support means for motion relative to said sound producing device, and said rod connected between said sensing means and said retainer member whereby movement of said sensing means shifts said retainer member to actuate said sound producing device.

8. The combination as defined in claim 1 wherein said door frame includes an inwardly extending ledge of substantially rectangular configuration and said door assembly includes a door and a keeper plate secured to, and spaced from, the interior surface of said door, and securement means for tightening said keeper plate against said ledge to mount said door flush with the exterior surface of said enclosure.

9. The combination as defined in claim 8 wherein said door assembly further includes a latch plate secured to the interior surface of said door, said latch plate having a slot formed therein, said mounting plate disposed above said latch plate and also having a slot formed therein, a pin securing said latch to said lock means to that said latch can be moved through said slots in response to actuation of said lock meaNs.