LOCK ASSEMBLY
United States Patent 3802230
This lock assembly includes a hollow cylindrical body having a central passage receiving a coaxial locking pin. The pin is provided with circumferentially spaced latching apertures and is latchable within the body by means of a latching sleeve having latching fingers engageable within said latch apertures. The pin is provided with a socketed end and is unlocked by means of a key having a barrel insertable within the socketed end, said key being provided with retractable unlatching fingers engageable with corresponding latch fingers of the pin to urge said latch fingers out of the latch apertures. The socketed end of the pin includes guide grooves receiving the retracted unlatching fingers and the remote end of the key is engageable with the pin to urge said pin from said body following the unlatching action.
Application Number:
05/320596
Publication Date:
04/09/1974
Filing Date:
01/02/1973
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
70/376, 70/409
International Classes:
E05B35/00; E05B63/12; E05B63/00; E05B67/36
Field of Search:
70/23,32,33,34,409,376
Primary Examiner:
Wolfe, Robert L.
Claims:
I claim as my invention
1. A lock assembly comprising:
2. An assembly as defined in claim 1, in which:
3. An assembly as defined in claim 2, in which:
4. An assembly as defined in claim 1, in which:
5. An assembly as defined in claim 4, in which:
6. An assembly as defined in claim 5, in which:
7. An assembly as defined in claim 1, in which:
8. A lock assembly comprising:
9. An assembly as defined in claim 8, in which:
10. An assembly as defined in claim 8, in which:
11. An assembly as defined in claim 8, in which:
12. An assembly as defined in claim 8, in which:
1. A lock assembly comprising:
2. An assembly as defined in claim 1, in which:
3. An assembly as defined in claim 2, in which:
4. An assembly as defined in claim 1, in which:
5. An assembly as defined in claim 4, in which:
6. An assembly as defined in claim 5, in which:
7. An assembly as defined in claim 1, in which:
8. A lock assembly comprising:
9. An assembly as defined in claim 8, in which:
10. An assembly as defined in claim 8, in which:
11. An assembly as defined in claim 8, in which:
12. An assembly as defined in claim 8, in which:
Description:
BACKGROUND OF THE INVENTION
This invention relates generally to tamper proof locks and particularly to a lock assembly for connecting gas meter valve parts together.
Protecting gas meter valves against unauthorized tampering has been a continuing problem and several attempts have been made to provide a successful tamper proof lock. Lock assemblies are known, which attempt to overcome the problem by employing a variety of mechanical principles. For example, in one type of lock, telescopic keys are provided which cooperate with movable latch parts within the lock; another type of lock utilizes a key having a wedgeable split shaft; and yet another utilizes a wedging principle by employing threadedly binding parts. In addition to the above, several known locks utilize spring loaded detent arrangements usually incorporating detent balls.
No known lock assembly utilizes elongate latch elements, which are unlatched by elongate, unlatching spring elements.
SUMMARY OF THE INVENTION
This lock assembly provides a means of securing the lugs of a gas meter valve together in a manner which precludes unlocking except by use of a specific key.
The lock assembly includes cooperating parts providing a pin and an overfitting cylindrical body, which are latched together by a specific arrangement of cantilevered, resilient latch fingers disposed within the body and engageable within compatible latching apertures provided around the pin. Unlatching is achieved by means of a key having a barrel portion, which is provided with a corresponding arrangement of cantilevered, resilient unlatching fingers engageable with said latch fingers and having a spring strength sufficient to overcome the resilience of the latch fingers and disengage said fingers from the pin.
The number, circumferential spacing, and chosen lengths of the latch fingers and cooperating unlatching fingers permits the use of various locking combinations.
The assembly is relatively simple and inexpensive to manufacture and the lock is simple to use.
It is an object of this invention to provide a lock assembly which includes a body having a longitudinal passage and latch means disposed within the passage said latch means providing a plurality of resilient latch elements. Pin means is provided which is insertable within the body passage to engage and move said latch elements outwardly, said pin means having a plurality of circumferential latch apertures communicating with a coaxial longitudinal passage, said latch apertures receiving the latch elements in latched relation. Key means is provided having a longitudinal barrel insertable within the pin passage in guided relation, said barrel providing a plurality of resilient unlatching elements receivable into associated latch apertures and being sufficiently resilient to engage and outwardly move associated latch elements out of the latch apertures.
It is another object to provide latch elements, each of which includes a longitudinally extending finger having a transverse end receivable into a latch aperture, and to provide unlatching elements each of which includes a longitudinally extending and depressible unlatching finger having a transverse end portion receivable into a latch aperture for engagement with the transverse end portion of an associated latch element.
It is a further object to provide a barrel portion of the key which includes a plurality of circumferentially spaced longitudinal recesses accommodating said unlatching fingers when said fingers are inwardly depressed, and to provide compatible longitudinal guide grooves disposed about the sidewall of the pin passage and communicating with the latch apertures, each groove receiving the transverse end of an unlatching finger in guided relation.
Another object is to provide unlatching fingers having cammed ends to facilitate insertion of the key into and out of the guide grooves of the pin passage.
It is an object to provide a body passage which includes a cavity housing the latch means, said latch means being provided by an independently formed cylindrical sleeve having at least two latch fingers of unequal length, and to provide at least two unlatching fingers of unequal length engageable with said latch fingers.
Another object is to provide a pin passage which includes a transverse end wall and a key barrel which includes a remote end, engageable with said end wall, to move said key and pin together to urge said pin out of said body passage.
It is an object of the invention to provide the portion of the pin extending outwardly of the cylindrical sleeve with an annular groove accommodating a hard steel, relatively rotatable sleeve to substantially preclude the cutting of the pin by a hacksaw or the like.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a side elevational view, partly in cross section, of the lock assembly in the latched position;
FIG. 2 is an elevational view, partly in cross section, of the key;
FIG. 3 is a sectional view taken on line 3--3 of FIG. 2;
FIG. 4 is an end view taken on line 4--4 of FIG. 1;
FIG. 5 is a fragmentary, cross sectional view taken on line 5--5 of FIG. 1; and
FIG. 6 is a fragmentary view, partly in cross section, illustrating the key in the operative, unlatching position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now by characters of reference to the drawing, and first to FIG. 1, it will be understood that the lock assembly is used to hold together two relatively movable parts such as the lugs 10 and 11 which are provided, in the preferred embodiment, on a gas meter valve, generally indicated by numeral 12. The locking of said lugs 10 and 11 maintains the valve in a shut-off position and precludes unauthorized use of said valve.
The lock assembly includes a cylindrical body 15 receiving a locking pin 16, which is coupled to the body 15 in the locked position by means of a latch sleeve 17, constituting a latch means. A key 18 is insertable within the pin 16 to unlatch the latch sleeve 17 and release the pin 16.
More specifically, the body 15 is provided with an axial passage 20 extending therethrough. The passage 20 provides a cavity 21, defined by a cylindrical wall 22 and annular end walls 23 and 24, said cavity being disposed between the pin entrance end 25 of the passage 20 and the key entrance end 26. The end 26 is beveled to provide an annular camming margin 27, and is defined in part by an annular wall 28 suitably configurated to provide an abutment engageable by the end of the locking pin 16 when said pin bottoms out.
At one end the locking pin 16 is provided with a head 30, which is compatibly shaped to be received within the tapered aperture 13 of the lug 10. The pin 16 also includes circumferential grooves 31 and 33, which are fitted with hardened steel sleeves 32 and 34 respectively. The outer diameter of said sleeves is smaller than the diameter of the lug apertures 13 and 14 and said sleeves are sufficiently loosely fitted in said grooves so that they can rotate. Because of this arrangement any attempt to saw through the pin 16, either between the lugs 10 and 11 or between the lug 11 and the body 15, simply results in rotation of the sleeves and thereby substantially hinders the sawing of said pin. At the other end the pin 16 includes a socket 35, constituting a longitudinal passage portion, and extending from the remote end of the pin to a socket end wall 36. The pin 16 also includes opposed pairs of latch apertures 37 and 40, constituting relatively depressed portions of said pin communicating with the socket 35. In the preferred embodiment apertures 37 are longitudinally spaced from apertures 40. As shown in FIG. 1, apertures 37 are defined by opposed walls 38 and 39, and apertures 40 are defined by opposed walls 41 and 42. The socket 35 includes a plurality of circumferentially spaced, longitudinal grooves 43 and 44 communicating between the open end of the socket 35 and associated apertures 37 and 40 respectively, said grooves constituting guide means.
The separate latch sleeve 17 is disposed within the cavity 21, and, in the preferred embodiment, is formed from relatively thin wall material. Said sleeve includes a base portion 50 and opposed pairs of inclined fingers 51 and 52 which are circumferentially spaced at ninety degree intervals and extend in cantilever relation from the base portion 50. The fingers 51 and 52, which constitute latch elements, are formed from a resilient material, such as spring steel, and are radially inwardly inclined in their unstressed condition. Fingers 51 are bent reentrantly to form transverse ends 53 providing opposed faces 54 and 55, which are adjacently disposed of and engageable with associated aperture walls 38 and 39. Fingers 52 likewise include transverse ends 56 providing opposed faces 57 and 58 adjacently disposed of and engageable with aperture walls 41 and 42 respectively. The base 50 of the latch sleeve 17 includes an end margin 59 adjacently disposed of the cavity end wall 24. The latch sleeve 17 is housed in longitudinally retained relation within the body cavity 21 by engagement between opposite ends of said latch sleeve and the spaced cavity end walls 23 and 24. It will be understood from FIG. 1 that the pin 16 is latched in place within the body 15 by engagement between the transverse ends 53 and 56 of the latch fingers 51 and 52 and the latch apertures 37 and 40 respectively.
As shown in FIG. 2, the key 18 includes a barrel 60, constituting a longitudinal barrel portion, and a head 61, which is provided with a key ring 62. The barrel 60 includes opposed recesses 63 and 64, which are circumferentially spaced about said barrel at ninety degree intervals and accommodate associated fingers 65 and 66 respectively. Said barrel 60 also includes a remote end providing a beveled camming margin 73 to facilitate insertion within the pin socket 35. The fingers 65 and 66, which constitute unlatching elements, are of a resilient material, such as spring steel, and are held at one end in cantilevered relation by fixed attachment to the barrel 60 as by welding. The resilient fingers 65 and 66 are depressible into a retracted position within associated recesses 63 and 64. Fingers 65 include transversely projecting ends 67 providing forward and rearward camming portions 68 and 69 and fingers 66 include transversely projecting ends 70 providing forward and rearward camming portions 71 and 72. The unlatching fingers 65 and 66 are substantially identical except that the projecting ends 67 and 70 are longitudinally spaced a distance substantially equal to the longitudinal spacing of associated latch apertures 37 and 40 of the pin 16. As shown in FIG. 6 the transversely projecting ends 67 and 70 of the unlatching fingers 65 and 66 engage the ends 53 and 56 respectively of the latch socket 35 and it will be understood that the resilience of said unlatching fingers is sufficiently great to move the engaged latch fingers out of the latch apertures 37 and 40 respectively. The longitudinal spacing of the apertures and fingers permits an almost infinite variety of locking combinations.
It is thought that the structural features and functional advantages of this lock assembly have become fully apparent from the foregoing description of parts but for completeness of disclosure the operation of the assembly will be briefly described.
The lugs 10 and 11 are secured together by the pin 16 by inserting said pin through the aligned apertures 13 and 14 of said lugs and by snapping the cylindrical body 15 into latched engagement on said pin. It will be understood that the transverse ends of the latch fingers 51 and 52, which would otherwise interrupt the path of the pin 16, are cammed outwardly by engagement with the beveled margin 47 at the remote end of the pin 16, and that said latch finger ends are suitably configurated to facilitate such camming. It will be further understood that the latch fingers 51 and 52 are accommodated within associated latch apertures 37 and 40 when the pin 16 bottoms within the body 15. The latch sleeve 17 is precluded from substantial longitudinal movement relative to said body 15 by the cavity end walls 23 and 24 and the pin 16 is, in effect, secured to said body.
The provision of rotatable sleeves 32 and 34 on the pin 16, at exposed portions of the pin, protects the lock assembly from destruction by hacksawing through the pin 16. In addition, said sleeves are preferably formed from hardened, high strength steel, which further hinders any attempt to cut the pin.
In order to unlatch the fingers 51 and 52 said fingers must be moved radially outwardly of the associated latch apertures 37 and 40. As shown in FIG. 6 this is accomplished by inserting the key 18 within the pin socket 35. It will be understood, that initially the key must be turned so that when the barrel 60 is inserted within the pin socket 35 the unlatching fingers 65 and 66 are aligned with associated guide grooves 43 and 44. As the key barrel 60 is inserted, the beveled margin 27 at the end of the body passage 20 engages the camming portions 68 and 71 of the unlatching fingers 65 and 66 respectively, depressing said fingers into retracted relation within associated longitudinal recesses 63 and 64. The guide grooves 43 and 44 are sufficiently deep to receive the projecting portion of the associated retracted unlatching fingers 65 and 66. The projecting ends 67 and 70 of said unlatching fingers are so spaced from the remote end of the barrel 60, as shown in FIG. 6, that when said barrel is bottomed out, by engagement with the socket end wall 36, said projecting ends are aligned with associated latch apertures 37 and 40 and move outwardly into engagement with the ends 53 and 56 of associated latch fingers 51 and 52, and urge said latch fingers out of said latch apertures. When the latch fingers are moved out of the latch apertures, continued pressure applied to the key 18 moves the key 18 and pin 16 together so that the pin is urged outwardly from the body 15. The key 18 and pin 16 are separated by drawing them apart, it being understood that the rearward camming faces 69 and 72 of the unlatching fingers 65 and 66 respectively depress said fingers into associated recesses as said camming faces are drawn into associated guide grooves to permit such separation. The ends of the guide grooves 43 and 44 are beveled to facilitate the camming of the unlatching fingers 65 and 66 during insertion and withdrawal of the key 16.
This invention relates generally to tamper proof locks and particularly to a lock assembly for connecting gas meter valve parts together.
Protecting gas meter valves against unauthorized tampering has been a continuing problem and several attempts have been made to provide a successful tamper proof lock. Lock assemblies are known, which attempt to overcome the problem by employing a variety of mechanical principles. For example, in one type of lock, telescopic keys are provided which cooperate with movable latch parts within the lock; another type of lock utilizes a key having a wedgeable split shaft; and yet another utilizes a wedging principle by employing threadedly binding parts. In addition to the above, several known locks utilize spring loaded detent arrangements usually incorporating detent balls.
No known lock assembly utilizes elongate latch elements, which are unlatched by elongate, unlatching spring elements.
SUMMARY OF THE INVENTION
This lock assembly provides a means of securing the lugs of a gas meter valve together in a manner which precludes unlocking except by use of a specific key.
The lock assembly includes cooperating parts providing a pin and an overfitting cylindrical body, which are latched together by a specific arrangement of cantilevered, resilient latch fingers disposed within the body and engageable within compatible latching apertures provided around the pin. Unlatching is achieved by means of a key having a barrel portion, which is provided with a corresponding arrangement of cantilevered, resilient unlatching fingers engageable with said latch fingers and having a spring strength sufficient to overcome the resilience of the latch fingers and disengage said fingers from the pin.
The number, circumferential spacing, and chosen lengths of the latch fingers and cooperating unlatching fingers permits the use of various locking combinations.
The assembly is relatively simple and inexpensive to manufacture and the lock is simple to use.
It is an object of this invention to provide a lock assembly which includes a body having a longitudinal passage and latch means disposed within the passage said latch means providing a plurality of resilient latch elements. Pin means is provided which is insertable within the body passage to engage and move said latch elements outwardly, said pin means having a plurality of circumferential latch apertures communicating with a coaxial longitudinal passage, said latch apertures receiving the latch elements in latched relation. Key means is provided having a longitudinal barrel insertable within the pin passage in guided relation, said barrel providing a plurality of resilient unlatching elements receivable into associated latch apertures and being sufficiently resilient to engage and outwardly move associated latch elements out of the latch apertures.
It is another object to provide latch elements, each of which includes a longitudinally extending finger having a transverse end receivable into a latch aperture, and to provide unlatching elements each of which includes a longitudinally extending and depressible unlatching finger having a transverse end portion receivable into a latch aperture for engagement with the transverse end portion of an associated latch element.
It is a further object to provide a barrel portion of the key which includes a plurality of circumferentially spaced longitudinal recesses accommodating said unlatching fingers when said fingers are inwardly depressed, and to provide compatible longitudinal guide grooves disposed about the sidewall of the pin passage and communicating with the latch apertures, each groove receiving the transverse end of an unlatching finger in guided relation.
Another object is to provide unlatching fingers having cammed ends to facilitate insertion of the key into and out of the guide grooves of the pin passage.
It is an object to provide a body passage which includes a cavity housing the latch means, said latch means being provided by an independently formed cylindrical sleeve having at least two latch fingers of unequal length, and to provide at least two unlatching fingers of unequal length engageable with said latch fingers.
Another object is to provide a pin passage which includes a transverse end wall and a key barrel which includes a remote end, engageable with said end wall, to move said key and pin together to urge said pin out of said body passage.
It is an object of the invention to provide the portion of the pin extending outwardly of the cylindrical sleeve with an annular groove accommodating a hard steel, relatively rotatable sleeve to substantially preclude the cutting of the pin by a hacksaw or the like.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a side elevational view, partly in cross section, of the lock assembly in the latched position;
FIG. 2 is an elevational view, partly in cross section, of the key;
FIG. 3 is a sectional view taken on line 3--3 of FIG. 2;
FIG. 4 is an end view taken on line 4--4 of FIG. 1;
FIG. 5 is a fragmentary, cross sectional view taken on line 5--5 of FIG. 1; and
FIG. 6 is a fragmentary view, partly in cross section, illustrating the key in the operative, unlatching position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now by characters of reference to the drawing, and first to FIG. 1, it will be understood that the lock assembly is used to hold together two relatively movable parts such as the lugs 10 and 11 which are provided, in the preferred embodiment, on a gas meter valve, generally indicated by numeral 12. The locking of said lugs 10 and 11 maintains the valve in a shut-off position and precludes unauthorized use of said valve.
The lock assembly includes a cylindrical body 15 receiving a locking pin 16, which is coupled to the body 15 in the locked position by means of a latch sleeve 17, constituting a latch means. A key 18 is insertable within the pin 16 to unlatch the latch sleeve 17 and release the pin 16.
More specifically, the body 15 is provided with an axial passage 20 extending therethrough. The passage 20 provides a cavity 21, defined by a cylindrical wall 22 and annular end walls 23 and 24, said cavity being disposed between the pin entrance end 25 of the passage 20 and the key entrance end 26. The end 26 is beveled to provide an annular camming margin 27, and is defined in part by an annular wall 28 suitably configurated to provide an abutment engageable by the end of the locking pin 16 when said pin bottoms out.
At one end the locking pin 16 is provided with a head 30, which is compatibly shaped to be received within the tapered aperture 13 of the lug 10. The pin 16 also includes circumferential grooves 31 and 33, which are fitted with hardened steel sleeves 32 and 34 respectively. The outer diameter of said sleeves is smaller than the diameter of the lug apertures 13 and 14 and said sleeves are sufficiently loosely fitted in said grooves so that they can rotate. Because of this arrangement any attempt to saw through the pin 16, either between the lugs 10 and 11 or between the lug 11 and the body 15, simply results in rotation of the sleeves and thereby substantially hinders the sawing of said pin. At the other end the pin 16 includes a socket 35, constituting a longitudinal passage portion, and extending from the remote end of the pin to a socket end wall 36. The pin 16 also includes opposed pairs of latch apertures 37 and 40, constituting relatively depressed portions of said pin communicating with the socket 35. In the preferred embodiment apertures 37 are longitudinally spaced from apertures 40. As shown in FIG. 1, apertures 37 are defined by opposed walls 38 and 39, and apertures 40 are defined by opposed walls 41 and 42. The socket 35 includes a plurality of circumferentially spaced, longitudinal grooves 43 and 44 communicating between the open end of the socket 35 and associated apertures 37 and 40 respectively, said grooves constituting guide means.
The separate latch sleeve 17 is disposed within the cavity 21, and, in the preferred embodiment, is formed from relatively thin wall material. Said sleeve includes a base portion 50 and opposed pairs of inclined fingers 51 and 52 which are circumferentially spaced at ninety degree intervals and extend in cantilever relation from the base portion 50. The fingers 51 and 52, which constitute latch elements, are formed from a resilient material, such as spring steel, and are radially inwardly inclined in their unstressed condition. Fingers 51 are bent reentrantly to form transverse ends 53 providing opposed faces 54 and 55, which are adjacently disposed of and engageable with associated aperture walls 38 and 39. Fingers 52 likewise include transverse ends 56 providing opposed faces 57 and 58 adjacently disposed of and engageable with aperture walls 41 and 42 respectively. The base 50 of the latch sleeve 17 includes an end margin 59 adjacently disposed of the cavity end wall 24. The latch sleeve 17 is housed in longitudinally retained relation within the body cavity 21 by engagement between opposite ends of said latch sleeve and the spaced cavity end walls 23 and 24. It will be understood from FIG. 1 that the pin 16 is latched in place within the body 15 by engagement between the transverse ends 53 and 56 of the latch fingers 51 and 52 and the latch apertures 37 and 40 respectively.
As shown in FIG. 2, the key 18 includes a barrel 60, constituting a longitudinal barrel portion, and a head 61, which is provided with a key ring 62. The barrel 60 includes opposed recesses 63 and 64, which are circumferentially spaced about said barrel at ninety degree intervals and accommodate associated fingers 65 and 66 respectively. Said barrel 60 also includes a remote end providing a beveled camming margin 73 to facilitate insertion within the pin socket 35. The fingers 65 and 66, which constitute unlatching elements, are of a resilient material, such as spring steel, and are held at one end in cantilevered relation by fixed attachment to the barrel 60 as by welding. The resilient fingers 65 and 66 are depressible into a retracted position within associated recesses 63 and 64. Fingers 65 include transversely projecting ends 67 providing forward and rearward camming portions 68 and 69 and fingers 66 include transversely projecting ends 70 providing forward and rearward camming portions 71 and 72. The unlatching fingers 65 and 66 are substantially identical except that the projecting ends 67 and 70 are longitudinally spaced a distance substantially equal to the longitudinal spacing of associated latch apertures 37 and 40 of the pin 16. As shown in FIG. 6 the transversely projecting ends 67 and 70 of the unlatching fingers 65 and 66 engage the ends 53 and 56 respectively of the latch socket 35 and it will be understood that the resilience of said unlatching fingers is sufficiently great to move the engaged latch fingers out of the latch apertures 37 and 40 respectively. The longitudinal spacing of the apertures and fingers permits an almost infinite variety of locking combinations.
It is thought that the structural features and functional advantages of this lock assembly have become fully apparent from the foregoing description of parts but for completeness of disclosure the operation of the assembly will be briefly described.
The lugs 10 and 11 are secured together by the pin 16 by inserting said pin through the aligned apertures 13 and 14 of said lugs and by snapping the cylindrical body 15 into latched engagement on said pin. It will be understood that the transverse ends of the latch fingers 51 and 52, which would otherwise interrupt the path of the pin 16, are cammed outwardly by engagement with the beveled margin 47 at the remote end of the pin 16, and that said latch finger ends are suitably configurated to facilitate such camming. It will be further understood that the latch fingers 51 and 52 are accommodated within associated latch apertures 37 and 40 when the pin 16 bottoms within the body 15. The latch sleeve 17 is precluded from substantial longitudinal movement relative to said body 15 by the cavity end walls 23 and 24 and the pin 16 is, in effect, secured to said body.
The provision of rotatable sleeves 32 and 34 on the pin 16, at exposed portions of the pin, protects the lock assembly from destruction by hacksawing through the pin 16. In addition, said sleeves are preferably formed from hardened, high strength steel, which further hinders any attempt to cut the pin.
In order to unlatch the fingers 51 and 52 said fingers must be moved radially outwardly of the associated latch apertures 37 and 40. As shown in FIG. 6 this is accomplished by inserting the key 18 within the pin socket 35. It will be understood, that initially the key must be turned so that when the barrel 60 is inserted within the pin socket 35 the unlatching fingers 65 and 66 are aligned with associated guide grooves 43 and 44. As the key barrel 60 is inserted, the beveled margin 27 at the end of the body passage 20 engages the camming portions 68 and 71 of the unlatching fingers 65 and 66 respectively, depressing said fingers into retracted relation within associated longitudinal recesses 63 and 64. The guide grooves 43 and 44 are sufficiently deep to receive the projecting portion of the associated retracted unlatching fingers 65 and 66. The projecting ends 67 and 70 of said unlatching fingers are so spaced from the remote end of the barrel 60, as shown in FIG. 6, that when said barrel is bottomed out, by engagement with the socket end wall 36, said projecting ends are aligned with associated latch apertures 37 and 40 and move outwardly into engagement with the ends 53 and 56 of associated latch fingers 51 and 52, and urge said latch fingers out of said latch apertures. When the latch fingers are moved out of the latch apertures, continued pressure applied to the key 18 moves the key 18 and pin 16 together so that the pin is urged outwardly from the body 15. The key 18 and pin 16 are separated by drawing them apart, it being understood that the rearward camming faces 69 and 72 of the unlatching fingers 65 and 66 respectively depress said fingers into associated recesses as said camming faces are drawn into associated guide grooves to permit such separation. The ends of the guide grooves 43 and 44 are beveled to facilitate the camming of the unlatching fingers 65 and 66 during insertion and withdrawal of the key 16.