US3912311A

US3912311A - Deadlock for sliding doors

Info

Publication number: US3912311A
Application number: US440452A
Authority: US
Inventors: Bernard J Carvell; W Nelson Sandford; C Michael Zimmerman
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-02-07
Filing date: 1974-02-07
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14

Abstract

An accessory lock especially adapted for sliding glass doors is described. The locking includes a locking cylinder which has a groove extending axially into the periphery. A housing for the cylinder is rigidly mountable adjacent the edge of a door at a location at which when the door is closed, a strike protruding from the frame for the door opening intersects the path of rotation of the cylinder and is received within the groove. A pin which projects radially outward from the cylinder extends through a transverse slot in the housing. The pin normally rides in the slot when the door is opened or closed. However, such pin is so shaped that upon rotating the same about its own axis 90*, it will coact with the housing slot to prevent rotation of the cylinder when the door is closed, thus trapping the strike and preventing opening of the door.

Description

States Patent" [191 Carvell et al.

[451 Oct. 14, 1975 DEADLOCK FOR SLIDING DOORS [76] Inventors: Bernard J. Carvell, PO. Box 4092, Foster City, Calif. 94404; W. Nelson -Sandf0rd 5734 Tucson Drive, San

Jose, Calif. 95150; C. Michael Zimmerman, 160 Redland Road, Woodside, Calif. 94062 22 Filed: Feb. 7, 1974 21 Appl. No.: 440,452

[52] US. Cl. 292/216; 292/78; 292/210;

292/341.l7; 292/DIG. 46 [51] Int. Cl. EOSC 3/04; EOSC 3/14 [58] Field of Search 292/57-5 8,

292/78, 216, 304, 210, 73, 261, 341.17, DIG. 42, DIG. 46, DIG. 51

[56] References Cited UNITED STATES PATENTS 278,854 4/1860 Worthen.... 292/34l.17

462,183 10/1891 Varney 292/210 697,933 4/1902 Blatchley... 292/57 770,837 9/1904 Wells 292/78 961,778 6/1910 John 292/57 973,358 10/1910 Liers 292/341.17 X 1,657,423 1/1928 VanDuzer.. 292/78 2,116,001 5/1938 Sch1age.., 292/57 X 2,978,266 4/1961 Poe 292/57 FOREIGN PATENTS OR APPLICATIONS 1,205,630 9/1970 United Kingdom 292/216 1,199,916 12/1959 France 292/216 Primary Examiner-Paul R. Gilliam Assistant ExaminerCarl F. Pietruszka Attorney, Agent, or FirmC. Michael Zimmerman, Esq.

[ ABS IRACT An accessory lock especially adapted for sliding glass doors is described. The locking includes a locking cyl-- inder which has a groove extending axially into the periphery. A housing for the cylinder is rigidly mountable adjacent the edge of a door at a location at which when the door is closed, a strike protruding from the frame for the door opening intersects the path of rotation of the cylinder and is received within the groove. A pin which projects radially outward from the cylinder extends through a transverse slot in the housing. The pin normally rides in the slot when the door is opened or closed. However; such pin is so shaped that upon rotating the same about its own axis 90, it will coact with the housing slot to prevent rotation of the cylinder when the door is closed, thus trapping the strike and preventing opening of the door.

5 Claims, 10 Drawing Figures US. Patent Oct. 14, 1975 Sheet 1 of2 3,912,311

US. Patent 0a. 14, 1975 Sheet 2 of 2 DEADLOCK FOR SLIDING DOORS BACKGROUND OF THE INVENTION The present invention relates to a deadlock for securely locking an opening closure in its closed position and, more particularly, to such a deadlock which is especially useful in locking sliding doors in a fail-safe and tamper-proof manner.

In the past several years, there has been a sharp rise in the number of home burglaries.'In this connection, burglars are gaining unauthorized entry into most homes without much difficulty. Unauthorized entry through sliding glass doors of the type commonly used to provide access to patios, decks and the like is especially easy. Such sliding doors are often installed in new housing units, making new homes, which are a favorite target of burglars, particularly vulnerable.

Although most sliding doors are equipped by their manufacturer with locks of one sort or another, such locks are generally not sufficient to prevent unauthorized entry. For one thing, standard locks for sliding doors are generally of a relatively flimsy nature, with the result that they can be forced to permit a door to be opened. Moreover, most do not prevent lifting of a sliding glass door and consequent removal of it merely by disengaging it from its tracks.

Because burglars generally wish to avoid the noise associated with the breaking of glass for entry, the provision of a satisfactory lock on a sliding glass door will be a deterrent to burglary. For this reason, many different accessory locks for sliding glass doors have been made available. In general, though, such locks are either inconvenient to use or have other deficiencies which render them less than fully satisfactory. For example, some accessory locks are simply blocks of one sort or another which sit within the track of the sliding door to prevent it from being opened. Such blocks must, of course, be placed within the track after each time the door is opened, and it is not unusual for one to forget or to otherwise fail to perform this task. Other auxiliary locks are designed to be mounted on a floor adjacent the door for engagement with it in one way or another to prevent its opening. Locks of this type often must be installed at a location on the floor at which they can be tripped over by anyone passing through the door opening. Many are also of a somewhat flimsy nature which not only makes them susceptible to forcing, but also easily damaged by inadvertent kicking or stepping.

SUMMARY OF THE INVENTION The present invention relates to a deadlock which is structurally quite strong and yet quite convenient to use. In its basic aspects, the deadlock includes a cylindrical locking block which is preferably massive, e.g., solid and of a metal. Such locking cylinder is provided with an axially extending groove projecting thereinto from its outer periphery. A housing supports the locking cylinder for rotation on its cylindrical axis and consequent travel of the longitudinally extending sides of the groove on a circular path. The housing is rigidly mountable adjacent the edge of either an opening closure, such as a door, or the frame for the opening closure, at a location at which when the door is closed, a strike protruding from the frame or door will intersect the cylindrical path of the groove sides in the locking block.

The opposed longitudinally CXlBI'IUlZlg sides of the groove are so positioned within the block that upon the door or other closure being closed, the strike will engage a first one of such groove sides and cause rotation of the locking block in a first direction positioning the other of the groove sides at a location blocking the return path the strike follows when the door is opened. The second groove side is also so positioned in the block that when the door is opened, the strike will engage such second groove side and cause the block to rotate in its reverse direction in order to both move the second groove side from its blocking location and again position the first'groove side in the path of the strike for engagement by it when the door is again closed. Releasable means are provided for selectively preventing rotation of the block in the reverse direction removing the second groove side from blocking the return path,

whereby the door will be maintained by the lock in its closed position. The above simple structure will result in the locking cylinder being brought to a locking position whenever the door is closed, and being automatically cocked whenever the door is opened for subsequent rotation into the locking position when the door is again closed. Because the part of the lock which causes the actual locking action is thus automatically moved to its proper positions whenever the door is opened or closed, the amount of additional effort involved in causing locking can be minimized, even though the cylindrical block is generally heavier than the moving parts of other locking mechanisms.

Most simply, the releasable locking means includes a pin which is secured to the cylindrical locking block and extends generally radially outward therefrom through a slot extending transversely through the housing. The pin will thus move along such slot upon the rotation of the cylindrical block between the door open and door closed positions. Most desirably, the pin is not circular in transverse cross-section where it passes through the slot, but has a dimension in one direction which is less than its dimension in another direction orthogonal thereto, and the width of the slot is such that it will accommodate the sliding movement of-the pin therealong only when the shorter pin dimension extends in the direction of suchwidth. The result is that by merely rotating the pin, it; will be prevented from sliding along the slot and, hence, the locking cylinder will be prevented from rotating on its cylindrical axis to remove the same from the return path of the strike. Thus, the actual operation to cause a desired door locking action by the relatively massive locking block is a mere rotation of a pin. The slot is enlarged to permit such pin rotation at the location at which the pin is positioned when the locking cylinder blocks the return path of the strike in order to permit such pin rotation.

The deadlock of the invention also most desirably includes structure which prevents the door from being lifted from its track'whenever it is in its closed position. To this end, transversely extending stops, most simply part of the locking cylinder housing, are spaced axially of the locking block at locations at which when the protruding strike end is engaged within the deadlock, movement of such strike longitudinally or vertically within the locking block groove is constrained by such stops. The prevention of relative vertical movement between the strike and lock will likewise prevent such vertical movement between the door and frame, the members to which such strike and lock are secured.

Thus, lifting of the door in the frame is prevented at the lock location.

The invention includes other features and advantages which will become apparent or will be described from the following, more detailed description of a preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the two accompanying sheets of drawings:

FIGS. 1 and 2 are partial isometric views illustrating a preferred embodiment of the deadlock of the invention mounted in position ,to provide locking for a sliding glass door, FIG. 1 showing the door in its closed position with the lock secured, and FIG. 2 illustrating the door open;

FIGS. 3 and 4 are enlarged, partial cross sectional views taken respectively on planes indicated by the lines 3--3 and 44 in FIGS. 1 and 2, showing details of the lock construction and its operation;

FIG. 5 is an enlarged, exploded isometric view of the preferred embodiment of the deadlock of the invention;

FIG. 6 is a sectional and broken-away view of the deadlock of the invention illustrating aspects of its construction;

FIG. 7 is an enlarged, partial sectional view illustrating details of the releasable locking means of the preferred embodiment;

FIG. 8 is a sectional view taken on the plane indicated by the lines 8-8 in FIG. 7 illustrating the relationship of the pin and slot when the lock is in a door locked position;

FIG. 9 is a sectional view similar to that of FIG. 8 except illustrating the relationship of the pin and slot when the releasable locking means is in a door unlocked position; and

FIG. 10 is another sectional view of the releasable locking means taken on a plane indicated by the lines 10-10 in FIG. 7 and illustrating further details of its construction.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT With reference first to FIGS. 1 and 2, a preferred embodiment of the deadlock of the invention, generally referred to by the reference numeral 11, is illustrated rigidly mounted adjacent meeting edges of a sliding glass door 12 and the frame 13 surrounding the opening for such door. The main structure 14 of the lock is that portion mounted on the door, at a location at which it will coact in a manner to be described with an end 16 of a strike 17 protruding from the door frame 13 into the door opening.

The main structure 14 of the deadlock 11 includes a locking block 18 having a circular cylindrical outer periphery. As a particularly important feature of the instant invention, the block 18 is provided with an axially extending groove 19 which projects generally radially inwardly thereof, and the block is rotatable on its cylindrical axis (represented at 21 in FIG. 5) with the result that the opposed longitudinal sides 22 and 23 of the groove will travel on a circular cylindrical path.

The main structure 14 of the deadlock further includes a housing for the rotatable block 18 which is rigidly mountable to the door for supporting such block at an appropriate location so that when the door is closed, the cylindrical path of the groove sides 22 and 23 is intersected by the protruding end 14 of the strike. Such housing is made up by a main member 24 having a generally semi-cylindrical reentrant portion defining a cavity 26 within which the cylindrical block 18 is received. As best illustrated in FIGS. 3 and 4, the cavity 26 has a circular cylindrical section surface 27 which mates and coacts with the outer periphery of the locking block to define the latters rotation and, hence, the cylindrical path of the grooves opposed sides 22 and 23. In this connection, it can be noted from FIG. 6 that the cylindrical block 18 extends generally for the full length of the cavity and is provided with end projections 28 on the cylindrical axis thereof which are engageable with the opposed ends 29 of the cavity to define bearings for such rotation.

The housing also includes a closure plate 31 which closes the cavity 29 and retains the cylindrical block 18 therein. More particularly, as can be seen from FIG. 6, the peripheral edge of the plate fits within a recess 32 at the opening into the cavity. Such plate also includes a reentrant arcuate section 33 (see FIG. 5) which acts as a continuation of the cylindrical surface within the cavity.

The main member 24 of the housing is notched longitudinally at 34 to define, in effect, a slot extending from the exterior of the housing into the cavity enabling passage of the protruding end 16 of the strike into such cavity for coaction with the locking block. FIGS. 3 and 4 illustrate such coaction. That is, by comparing FIGS. 3 and 4, it will be seen that when the door is brought to its closed position, the end 16 of the strike will enter through the slot in the housing and engage the longitudinal side 22 of the groove 19 to rotate the block to bring the groove side 23 into the position shown in FIG. 3 blocking the return path the strike end takes when the door is opened. Thus, every time the door is closed,

the locking block 18 is automatically brought into the door locking position.

When the door is opened, the strike end 16 will engage the side 23 of the groove 19 to rotate the locking block 18 in its reverse direction, assuming, of course, that the deadlock has not been actuated to prevent such reverse rotation. As can be seen from FIG. 4, reverse rotation of the block not only moves the groove side 23 from its blocking position, but also again places the groove side 22 in the path of the strike for engagement thereby when the door is again closed. Thus, when the door is opened, the deadlock is returned to the proper condition for receiving the strike end when the door is again closed.

It will be recognized from the above that because every time the door is closed, the relatively massive locking block is brought into the proper position for locking the door, the deadlock of the invention readily lends itself to a simple manipulation to cause the desired locking. To this end, a simple releasable locking means is provided for selectively preventing rotation of the block in the reverse direction once it is in the position shown in FIG. 3, thereby preventing the strike from being removed from within the groove and, hence, the door from being opened. Such means includes a pin 36 which extends radially outward from the locking block and through a transversely extending slot 37 in the housing. The pin 36 rides within such slot 37 upon rotation of the locking block. In this connection, as shown in FIGS. 3 and 4, the ends of the slot are so positioned that they cooperate with the pin to constrain the locking block rotation to between positions of the groove corresponding to when the door is closed and opened.

Pin 36 is rotatably secured within the locking block 18. That is, as is apparent from FIGS. 6 and 7, the pin 36 extends through a bore in the locking block and terminates in a snubbing end 38 which extends into a recess 39 projecting into the locking block from the side thereof opposite the pin. A locking grip washer 40 is positioned within the recess 39 and receives the snubbing end 38 of the pin 36 to hold the pin within the block while allowing it to be rotated with respect to such block.

The portion of the pin 36 which rides within the slot 37 does not have a circular transverse cross-section, but rather is provided with a dimension in one direction which is less than in another direction orthogonal thereto. It is this dimension relationship and the manner in which it coacts with the dimensions of the slot 37 which enable mere rotation of the pin to actuate the deadlock to its locked position. More particularly, the pin 36 is provided with

shoulders

41 and 42 projecting from opposite sides of its side periphery at the location at which such pin passes through slot 37. As can be seen by comparing FIGS. 8 and 9, the width of the pin when the

shoulders

41 and 42 are aligned with the length of the slot, i.e., when the lesser dimension of the pin extends in the direction of the slot width, is such that the pin can move along the full length of the slot. Thus, the pin will not obstruct rotation of the block or movement of the strike end 16 from the groove and, hence, opening of the door. However, when the pin is rotated by ninety degrees, the shoulders on the pin prevent the same from traveling along the slot as shown in FIG. 8. The location of the slot at which it is enlarged to permit rotation of the pin to place such shoulders in the position shown in FIG. 8 is at that end of the slot at which the pin is located when the door is closed, i.e., when the groove in the locking block is positioned to block the return path of the strike.

It will thus be seen that merely by rotating the pin 36, 90, the deadlock of the invention provides locking of the door in its closed position. An enlarged head 43 is provided on the free end of the pin to facilitate such rotation. Moreover, coacting structure is provided on the pin and the housing to prevent it being rotated any more than the ninety degrees necessary to move it between its unlocked and locked positions. That is, as can be seen from FIG. 10, an arcuate shoulder 44 projects upwardly from the recess 45 with the locking block within which the pin shoulders 41 and 42 ride. Such shoulder 44 extends generally semi-circularly around the pin 36 along that path the shoulder 41 of the pin travels when the pin is rotated between the locked and unlocked positions shown in FIGS. 8 and 9. As best seen from FIG. 7, the shoulder 42 extends further into the recess 45 than does the shoulder 41. The result is that the arcuate shoulder 44 in the recess acts as a stop which is engaged by the pin shoulder 42 to limit the rotation of such pin between the locked and unlocked positions.

It will be recognized that when the strike end 16 is received through the housing slot and is engaged within the groove 19, such protruding strike end is positioned between the upper and lower ends 29 of the housing. The length dimension ofthe strike end is chosen so that when it is so positioned, any appreciable movement of such strike vertically within the slot is prevented. The transversely extending ends 29 of the housing thus act, in effect, as stops which are spaced axially of the locking block to constrain vertical movement of the strike relative to the main structure of the lock. Such vertical movement is thus also restrained between the door and the frame and, hence, lifting of the door from the frame is prevented.

In order to facilitate its installation on differing door and frame designs, the preferred embodiment of the invention includes several features which permit adjustment to assure proper fitting. For one, as can be seen from FIGS. 3 through 5, the strike 16 is in the form of an angle iron section having one leg, leg 46, longer than its other leg, leg 47. Also, each of the legs is provided with apertures 48 through which fasteners, such as screws 49, can extend to secure the strike to a door frame so that the other one of the legs is the one which protrudes from the frame for receipt within the groove 19 of the cylindrical block. Moreover, the free ends of both of the legs have a configuration which is amenable with such intersection and rotation of the cylindrical block as described. Thus, either of the legs can be se lected during installation to be the protruding strike leg, merely by turning the strike over. Because of the different lengths of such legs, differing distances between the location at which a strike can be secured to a frame and the location at which a main locking structure can be secured to a door can therefore be accommodated.

As another adjustment feature, a shim plate 51 is also included as part of the main structure of the lock. Such shim plate is positionable, if desired, between the housing and the door to which such housing is to be mounted, to thereby space the housing from the door. To this end, the shim plate includes a base 52 having a peripheral flange 53 extending from it to define a cavity within which the housing is fittable. As is best illustrated in FIGS. 3 and 4, a flange 53 extends orthogonally from the base on both sides of the latter to thereby define such a cavity on each side of the base. Moreover, the distance the flange extends beyond the base on each side thereof is different than the distance it extends therefrom on the other. It will therefore be recognized that by choosing which shim cavity receives the housing when it is mounted on a door, a selected one of the flanges 53 will be made to abut against the door for spacing the shim base and, hence, the housing from such door. The different dimensions of such flanges thereby permit the shim to be used to obtain two different spacings of the main structure of the lock from the door.

The shim plate 51 is adapted to be independently secured to the door, as well as secured to such door along with the remainder of the main structure of the dealock. More particularly, the base of such shim is provided with a central aperture 56 which is adapted to receive a fastening screw 57. The closure plate 31 for the housing is provided with a registering aperture 58 to accommodate the head of such screw. The remainder of the main structure of the deadlock is rigidly mountable to the door via screws 59 which extend through apertures 61 adjacent the upper and lower ends of the main member 24 of the housing structure. As illustrated, such screws also extend through registering apertures 62 in the shim plate 51. The screws 59 will thus provide a rigid mounting of the full main structure of the lock to the door. Furthermore, because the structure securing the lock to the door, i.e., the screws 59 and the screw 49 for the strikeplate, are only accessible from the inside of the door, tampering with the same from the exterior is inhibited.

While the inventionhas been described in connection with a preferred embodiment thereof, it will be appreciated by those skilled in the art that various changes and modifications can be made without departing from its scope. For example, the positioning of the. main structure of the lock and strike is interchangeable. That is, the protruding strike can be provided on the door and the main structure on the door frame. Moreover, although the lock is especially designed for usewith sliding glass doors and the like, it will be recognized that it is equally as useful for locking other closures within their frames. It is therefore intended that thecoverage afforded applicants be limited only by the language of the claims and its equivalent.

We claim: 7 LA deadlock for securing an opening closure in its closed position within a frame defining the opening to be closed comprising: an elongated locking block cylinder having a circular cylindrical outer periphery with an axially extending groove projecting inwardly thereof, which locking block is rotatable on its cylindrical axis for travel of inwardly and longitudinally extending opposed sides of said groove on a circular cylindrical path; a housing having a cavity therein defined by an interior circular cylindrical section surface which coacts and mates with said cylindrical outer periphery of said'locking block to define said cylindrical path, said housing having a slot extending into said cavity for passage of a protruding strike endinto said cavity for intersection thereby of said cylindrical path and being rigidly mountable adjacent an edge of one of said opening closure and said frame forsupporting said block at a location at which when said closure is in its closed position, said cylindrical path of said groove sides of said block is intersected by said strike end protruding from the other end of said closure and said frame whenever said opening closure is moved to its closed position; said opposed sides of said groove being positioned in said block for engagement of a first one thereof by said strike end upon movement of said closure toward its closed position to rotate said block in a first direction and position the second one of said opposed groove sides blocking the return path said strike end follows when said closure is moved toward its open position, and for engagement of said second groove side by said strike end upon movement of said closure toward its open position to rotate said block in a reverse direction and move said second groove side from said blocking location and again positionsaid first groove side in the path of said strike end for engagement thereby when said closure is again moved toward its closed position; and releasable locking means for selectively preventing rotation of said block in said reverse direction moving said second groove side from blocking said return path whereby said closure is maintained by said deadlock in its closed position, said releasable locking means including a pin extending generally radially outward from said locking block through a transverse slot in said housing to the exterior thereof for manipulation and movement along said slot upon said rotation of said locking block, and means on said pin and housing adjacent the periphery of said locking block for preventing movement of said pin from its location in said slot selectively when said second groove side of said locking block is positioned blocking the return path of said strike, whereby said pin and housing are selectively cooperable to prevent rotation of said block in said reverse direction and thereby to lock said closure in its closed position.

2. The deadlock of claim 1 further including transversely extending stops spaced axially of said locking block and between which said protruding strike is positioned when said strike end intersects said circular cylindrical path, whereby movement of said strike longitudinally within said groove is constrained.

3. The deadlock of claim 1 wherein said pin has in transverse cross-section a dimension in one direction which is less than in another direction orthogonal thereto, and said slot has a width along its length accommodating movement of said pin therealong when said lesser dimension of said pin extends in the direction of said width but preventing movement of said .pin from its location at which said second groove side of said locking block is positioned blocking the return path of said strike when the greater dimension of said pin extends in the direction of said width, whereby rotation of said pin by exterior manipulation to place said longer dimension in the direction of the width of said slot results in said pin and housing cooperating to prevent said rotation of said block in said reverse direc-- tion.

4. The deadlock of claim 2 wherein said housing is provided by a main member having a generally semicylindrical reentrant portion defining said cavity circular cylindrical section surface, axially opposed ends of said'reentrant portion providing said stops for constraining longitudinal movement of said strike end when positioned within said cavity; said cylindrical locking block extending for the full length of said reentrant portion cavity and having end projections on the cylindrical axis thereof engageable with said reentrant portion opposed ends to define bearings for said rotation'of said locking block.

5. The deadlock of claim 3v further including cooperable means on said pin and said housing preventing rotation of said pin other than between said positions placing said lesser and said greater dimensions thereof in the direction of the width of said slot.

Claims

1. A deadlock for securing an opening closure in its closed position within a frame defining the opening to be closed comprising: an elongated locking block cylinder having a circular cylindrical outer periphery with an axially extending groove projecting inwardly thereof, which locking block is rotatable on its cylindrical axis for travel of inwardly and longitudinally extending opposed sides of said groove on a circular cylindrical path; a housing having a cavity therein defined by an interior circulAr cylindrical section surface which coacts and mates with said cylindrical outer periphery of said locking block to define said cylindrical path, said housing having a slot extending into said cavity for passage of a protruding strike end into said cavity for intersection thereby of said cylindrical path and being rigidly mountable adjacent an edge of one of said opening closure and said frame for supporting said block at a location at which when said closure is in its closed position, said cylindrical path of said groove sides of said block is intersected by said strike end protruding from the other end of said closure and said frame whenever said opening closure is moved to its closed position; said opposed sides of said groove being positioned in said block for engagement of a first one thereof by said strike end upon movement of said closure toward its closed position to rotate said block in a first direction and position the second one of said opposed groove sides blocking the return path said strike end follows when said closure is moved toward its open position, and for engagement of said second groove side by said strike end upon movement of said closure toward its open position to rotate said block in a reverse direction and move said second groove side from said blocking location and again position said first groove side in the path of said strike end for engagement thereby when said closure is again moved toward its closed position; and releasable locking means for selectively preventing rotation of said block in said reverse direction moving said second groove side from blocking said return path whereby said closure is maintained by said deadlock in its closed position, said releasable locking means including a pin extending generally radially outward from said locking block through a transverse slot in said housing to the exterior thereof for manipulation and movement along said slot upon said rotation of said locking block, and means on said pin and housing adjacent the periphery of said locking block for preventing movement of said pin from its location in said slot selectively when said second groove side of said locking block is positioned blocking the return path of said strike, whereby said pin and housing are selectively cooperable to prevent rotation of said block in said reverse direction and thereby to lock said closure in its closed position.

3. The deadlock of claim 1 wherein said pin has in transverse cross-section a dimension in one direction which is less than in another direction orthogonal thereto, and said slot has a width along its length accommodating movement of said pin therealong when said lesser dimension of said pin extends in the direction of said width but preventing movement of said pin from its location at which said second groove side of said locking block is positioned blocking the return path of said strike when the greater dimension of said pin extends in the direction of said width, whereby rotation of said pin by exterior manipulation to place said longer dimension in the direction of the width of said slot results in said pin and housing cooperating to prevent said rotation of said block in said reverse direction.

4. The deadlock of claim 2 wherein said housing is provided by a main member having a generally semi-cylindrical reentrant portion defining said cavity circular cylindrical section surface, axially opposed ends of said reentrant portion providing said stops for constraining longitudinal movement of said strike end when positioned within said cavity; said cylindrical locking block extending for the full length of said reentrant portion cavity and having end projections on the cylindrical Axis thereof engageable with said reentrant portion opposed ends to define bearings for said rotation of said locking block.

5. The deadlock of claim 3 further including cooperable means on said pin and said housing preventing rotation of said pin other than between said positions placing said lesser and said greater dimensions thereof in the direction of the width of said slot.