US 3002777 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Oct. 3, 1961 R. N. DU SHANE, JR 3,002,777
LATCH MECHANISM INVENTOR,
Oct. 3, 1961 R. N. Du SHANE, JR 3,002,777
LATCH MECHANISM Filed Sept. 16, 1957 2 Sheets-Sheet 2 INVENTOR.
l BY www United States Patent mesne assignments, to Acme Metal Molding Co., Los` Angeles, Calif., a corporation of 'California Filed Sept. '16, 1957, Ser. No. 684,194 6 Claims. (Cl. 292-78) This invention relates to -a latch mechanism and more particularly to a SeI-latching, non-jamming, and self-- releasing latch mechanism for sliding doors or panels.
Prior proposed latch mechanisms for sliding doors have included a latch member which was pivoted into latched engagement with a door plate or a door strike on an associated door jam member. Such a prior pivoted latch member was required to be manually actuated by a handle, thumb or finger engagement portion, or otherexternal actuating means. If the pivoted latch member were left in latched position and the door then closed, damage often resulted to the pivoted latch member and to other parts of the latch device because of impact forces acting upon the latch device when the door was closed. To obviate such a disadvantage, some pivoted latch members were then mounted in a oating manner so that if the latch member were left in latched position, upon striking a door jamb, the l-atch member would duck or retract into the latch casing and save the latch mechanism from damage. Even in such prior proposed latching devices, the latching mechanisms were not self-latching, nor Was it self-releasable, in that an external actuating means was required to be turned to movethe latch member into latched and unlatched positions.
' This invention contemplates an improved latch mechanism which is particularly adaptable to horizontal sliding doors or panels. The invention contemplates a latching mechanism which obviatesthe `disadvantages of prior proposed latching devices used on sliding doors and panels.
An object of this invention is'to disclose and provide a self-releasing, self-latching, non-jamming latch mechanism for a sliding door. ,A
Another object of this invention is to provide a selfreleasing latch mechanism whereby application of a force in a direction to open a closed sliding door will cause automatic unlatching of the door latch mechanism.
Another object of this invention is to disclose and p rovide a latch mechanism wherein a positive `locking device is readily externally actuated to lock the latch mechanism.
A further object of this invention is to provide a latch mechanism having a latch element movable into latched position upon contact of an associated sensing element with a strike plate and wherein a spring means associated with the latch element determines unlatched position thereof and biases the latch element toward latched position. p
A further object of this invention is to disclose and provide a latch mechanism which does not interfere With the clean simple design lines provided by a door frame or door stile member. i
A still further object of this invention is to disclose and provide a latch mechanism which requires no actuating handle or knob in order to cause latching or unlatching of the mechanism.
A still further object of this invention is to disclose and provide a latch mechanism which may include a rotatable latch member of spur wheel or sprocket, or rotary bolt design which may be positioned and yieldably held against rotation by spring means for `desired engagement With a strike plate.
Another object of this invention is to disclose and provide a simple, effective, inexpensive latch mechanism readily assembled and vinstalled in a sliding door.
Generally speaking, the latch mechanism of this inven- 'tion comprises a latch casing having a front opening in which may be rotatably mounted a rotary latch member.l
A spring means carried by the latch casing is designed to simultaneously pressure contact or engage means on the rotary latch member so as to maintain the latch member in a preselected position for proper latching engagement with a strike plate. A locking device may be pivot-ally carried by the latch casing and may be provided with a lock element positionable in the path of movement of the latch member in order to prevent rotation thereof in unlatching direction. Normally, the spring means yield- -ably restrains rotation yof the latch member in both latching and unlatching directions.
Other objects and advantages of this invention will be readily apparent from the following description of the drawings, in which an exemplary embodiment of this invention is shown.
In the drawings:
FIG. l is a fragmentary sectional view taken in `a vertical plane bisecting a latch mechanism embodying this invention and an associated door stile and door jamb, the latch mechanism being shown in latched but unlocked position.
FIG. 2 is a view taken in the same plane as FIG. 1 showing the latch mechanism in latched and locked position.
FIG. 3 is a transverse horizontal sectional view taken in the planes indicated by line III-IH of FIG. l.
FIG. 4 is a fragmentary sectional view taken in the same vertical plane as that of FIGS. l and 2, and shows the latch mechanism approaching a door jamb member for latching engagement therewith.
FIG. 5 is a perspective View of a latch casing shown in FIG. 1.
FIG. 6 is a perspective View of a locking device employed with the embodiment of the invention shown in FIG. l.
FIG. 7 is a schematic View of a modification of a latch mechanism embodying this invention, the mechanism being shown in approach position.
FIG. 8 is a view of the latch mechanism of FIG. 7 in locked position.
A latch mechanism embodying this invention is generally indicated at 15 and is illustrated as being installed in a horizontal sliding door or panel. It is understood that the latch mechanism may be installed in other sliding doors, panels, gates, or other means Where a panel is movable in a plane toward another member txed or movable for cooperable latching engagement therewith.
In this example, a sliding horizontal door only fragmentarily shown may include a vertical stile 16 having a suitable metal section including a pair of spaced parallel Wall members 17 providing therebetween a latch-receiving recess 18. Back wall 19 of the recess may be integral with the side Walls 17 and may also be integrally joined with an L-section flange 2i) providing a groove 21 for reception of retaining means 22 for a screen. cloth 23. The latch-receiving recess 1S may be provided with outwardly flaring internal wall surfaces 24 adjacent front opening 25 of spaced Walls 17.
A door jamb or frame member 27 may be made of any selected material and in this example includes an H-section metal extrusion including spaced parallel Walls 28 and an interconnecting intermediate web 29, said walls 28 facing stile member 16 and being spaced apart suiciently to readily receive thereinto front portions of stile 16. It is understood that jarnb member 27 may be a movable vertical member provided on lan adjacent sliding panel or may be a xed stationary frame member as shown.
Attached to the stile 16 of the sliding door may be a pair of oppositely laterally outwardly extending door pulls` Patented Oct. 3, 1961 32, said door pulls being of any suitable design and shape, and adapted to be grasped by a hand to move the sliding :door away from or toward the jamb member 27. Thev sifze and shape of door pulls 32 are not described in detail ybecause they do not form part of this invention, and
any shape or style of door pull may be employed.
A Alatch strike plate or member 34 may be secured centrally between walls 28 of H-section door jamb` member 27. Strike member 34 may be made from a single stamped piece of sheet metal. The strike member 34 may include a downwardly inclined top wall 35 integrally formedV with a depending front strike wall 36 and dependin'g'forwa'rdly converging integral side Walls 37. The side Walls l37 may be provided with rear inturned ilauges or lips 38 providing a vertical slot 39 which may adjustably, slidably receive securing screw 40. A port 41 may be provided in front wall 36 for access to the screw '40. It will thus be apparent that the latch strike member 34 may be adjustably vertically positioned in a facile manner on the door jamb member 27. The convergence of side walls 37 corresponds generally to the angle of the outwardly ared internal surfaces 24 on the walls 17 of stile 16. Thus as a stile l6'approaches jamb member 27, outwardly flared surfaces 24 provide a relatively wide opening for guiding and receiving thereinto the latch strike member 34. The inclined top wall 35 facilitates Vertical adjustment of strike member with respect to latch opening 49 in the latch housing.
Within the latch-receiving recess 18 provided in the stile 16 may be secured in any suitable manner a latch mechanism 42; of this invention. The latch mechanism 4Z may comprise a latch housing or casing yformed of two identical matching latch casing portions 43. Each casing portion 43 may include a vertical rectangular side wall 44 provided with a pair of spaced circular openings 44'. integrally formed with one end or top edge of side wall 44 may be spaced front and back inturned ilanges 45 and 46. Between said anges '45 and 46, and spaced inwardly or -therebelow may be a center inturned ilange or tab 47. The front top llange 45 may be integral with an upstanding securing lug 48. At the other end or bottom edge of each' side wall 44 may `be provided front and rear inturned flange portions 45' and 46. Between the bottom flanges 45 and 46 may be provided a center inturned flange or tab 47 spaced below the front and back a-nges 45 and 46. The other casing portion 43 is constructed identical to that just described and is matched in assembly with the rst casing portion by turning it upside down so that the top and bottom flanges 45, 45', 46, 46 and 47, 47 are yarranged in overlying interlocked relation. The center flanges 47, 47 are slightly vertically spaced apart and interleaved as spring-retaining means as later described. The securing lugs 48 may be secured to the front face of the stile 16 in `any suitable well known manner as by screw bolts.
Between front edges of side walls 44 is provided a latch opening 49 and extending forwardly from said opening and integral with each side wall 44 may be a centrally disposed projection 50, said projections 50 having axially aligned ports 51 lying at said front latch opening.
A rotary latch member 54 manl be mounted for rotation about an axis transverse to the opening 49 by `a suitablep-in 59 carried in said ports 51 provided in projections t). The latch member 54 may be made of any suitable material which is relatively rigid, strong, and quiet in operation, preferably a plastic material such as Teon. Latch member 54 may include a plurality of circiimferentially spaced yor circularly arranged latch elements 55 delining therebetween recesses 57. Each latch element 55 may comprise a convex outwardly directed face 56 of substantially semicircular configuration and a somewhat narrow neck portion 58. The radius of the latch member is such that when rotatably mounted on pin 59,*the convex faces 56` of the latch elements do not eX- tend beyond theedge of stile `16 so that said rotary latch mcnber'lieswithin latch-receiving opening 1'8 inthe Stile.
It will be understood that while a particular design of rotary latch member is shown, the rotary latch member may include other suitable configurati-ons in which a plurality of latch elements arranged such as elements 55 may serve in one of three functions; namely, as a latching element, as a sensing orrespnve' element cooperable with a strike plate, n' as a latch-positioning element cooperbl th' a s 'nieafns as`= later desj'ciibed.
A spring means s provided to yieldably hold latch member fiagainst': rotation 'in either direction and to hold and maintain' the' latch member in` a preselected position so as to properly engage and disengage with strike member 34. l The spring means 6 2 may be of flat narrow spring metal stock material, and may comprise a base portion 63 which may be seated between inturned center anges 47, 47 on latch casing V'portions 43. It will be readily apparent that base portion 631m assembly may be seated on a center flange 47 and when Athe other casing portion is assembled therewith, the cooperable centeij tlange 47 will overli'e ilange 47.y Springbase portiont6-3 may be forced between anges 47, 47 whereby the casing portions aren held yand retained in assembly and spring portion-,63 is held `iirmly therebetween and against lateral displacement.' The portion 63 may include a downturned end lip 64 to hold the spring against longitudinal displacement.
Integral with base portion 63 may be a depending latch member engagement portion 65, said latch member engagement portion 65 including ya generally curvilinear or semicircular end section 66 provided with a continuous convexouter surface having spaced convex engagement faces 67 and 68 for contact with spaced convex faces 56 p on `adjacent latch elements 55. In this exemplary construction, the center of the semicircular section 66 of the spring means lies in a plane disposed at about 30 to a horizontal plane passed tbroughthe axis of rotation of the rotary latch member 54. It'will thus be apparent that in this example, where the latch member includes six latch elements 55 that spring section 66 will position the latch elements in such a manner that a forwardly directed latch element 55a lies |horiztmtally so as to pass beneath wall 36 of strike member 34 and latch element 55b immediately thereabove lies at an angle of about 60 and in a position so as to strike the front face of front wall 36 thus serving to sensepand respond to the presence of wall 36 in its path of movement to turn the latch member 54.
It will thus -be apparent that when a sliding door carrying the latch mechanism of this invention approaches a door jamb member as shown in FIG. 4, a latch element 55h is disposed for striking and sensing engagement with front wall 36of thestrike member 34. As latch/element 55h contacts wall 36, the rotary .latch member is caused to turn in aclockwise latchingV direction as seen in FIG. 4, and against spring means 62.- As the rotary latch member turns, a rearwardly 'and angularly disposed latch element 55C will press further against the first Vconvex tace 67 on 4the spring means to displace section 66 rearwardly and to yieldably 'permit element 55e to move to horizontally 'disposedposition with convex face 68 in engagement therewith. 'I`he` front horizontally disposed latch element 55a is thus rotated upwardly into latched engagement withv the back face of wall 36 on the strike membei'. Uponenggement with the back face of wall 36', it Wil-l ybe noted that the latch member has turned approximately one-sixth of a circle and spring section `66 is again in position to hold therotary latch member against rotation in either dirc'tioiil It' should be noted that con- Vex face 68 presses againstface 56 on the latch element 55e in la downward direction to urge the latch member in clockwise latching direction of rotation. The convex face 67 presses against the associated latch element 55b 4to urge'the latch member in a counterclockwise unlat'ching direction oftrotation.y In present example, the Spring section sa andiatcn member s4 are se @sparsely arranged that the springfo'r'c'es acting on the latch inember are virtually symmetrical' and approximately balanced.
. If desired, fthe angular relationship of the rotary latch member and the spring section 66 may be varied so that latch element 55a will engage under selected pressure the back face of strike wall 36 and serve to resiliently draw the sliding door toward the door jamb member in an amount depending upon the spring force of spring means 62. The spring force to accomplish this snug drawing in ofthe sliding door may be provided by modifying the curvilinear configuration or" spring section 66 so that a greater spring force acts against the latch element 55C and the spring forces acting on adjacent latch elements 55b and 55e of the latch member are unbalanced. The construction of the spring means 62 may also be modified to provide a spring section 66 having a composite action in which the spring force at engagement `face 68 is greater than the spring force at engagement face 67.
As above described, it will be readily apparent that the rotary latch member 55' rotates clockwise as shown during closing movement of a sliding door to engage in latching relation the wall 36 on the strike member. When it is desired to open the door, the door pull 32 may be grasped and the door moved in a direction away from jamb member 27. Upon such movement of the door panel, it will be readily apparent that Wall 36 causes the rotary latch member 54 to rotate in a counterclockwise unlatching direction until bold head 55a which engaged the back face of the wall 36 is lowered `to pass underneath the bottom edge of wall 36. In such counterclockwise rotation, the latch member turns less than 45. In such turned 45 position, the spring section 66 engages between faces 67, 68 the convex face S6 of latch element 55C and on one side of a radium dening the axis of the latch element 55e. Thus as the latch element 55a clears strike wall 36, the spring means 62 causes the latch member to return so that upon next engagement with the strike member, `latch member 55b will strike wall 36.
When a sliding door is in closed position, and the latch mechanism of this invention is in latched position as shown in FIGS. l and 2, the rotary latch member may be locked against rotation in an unlatching direction by a lock means indicated at 70. Lock means 79 may comprise aliat, thin, partially circular, disk-like member 7l provided lwith a lock element 72 extending laterally therefrom at one peripheral edge. The lock element 72 extends through one opening 44' in latch casing wall 44 and is movable into and between the space 57 between latch elements 55. The lock element 72 may be of concave section so as to generally correspond on its one face with the convex curvature of a latch element 55. The member 7i may be pivotally mounted by a pivot pin 73, which extends into door pull 32. Door pull 32 may be relieved to provide a recess 74 to accommodate member 71 and wall 17 may be ported so that lock element 72 may extend therethrough.
In this example, lock means 70 may include external actuating means comprising angularly arranged ilat polygonal wing-like linger engagement portions 76 and 77, each adapted to seat in one position against surface 78 on door pull 32. Thus asshown in FIG. l, when finger engagement portion 76 is seated against the door pull surface 7S, lock element 72 is in retracted position in opening 44' and out of the path of movement of the latch member 54. When finger engagement portion 77 is pressed against surface 78 on the door pull, the lock device pivots about pin 73 to move the lock `element 72 into cooperable holding engagement with a latch element 55 as shown in FIG. 2. Thus the linger engagement portions 76V and 77 provide an attractive, unobtrusive, simple external actuating means for locking the rotary latch member S4 against rotation in a counterclockwise or unlatching direction.
Operation of the latch mechanism described above is readily apparent. Approach of the latch mechanism toward the latch strike member and contact therewith by sensing or strike responsive latch element 55b automatically causes rotation of the latch member so -as to position latch element 55a in latched engagement with the latch strike member. This latched engagement may be relatively loose or may be tight pressure engagement depending upon the preselected position which the rotary member is provided by its cooperable engagement with spring means 62. Latch elements 55o and 55d in cooperable engagement with spring section 66 serve to initially position the latch member so that element 55a will pass beneath wall 36 and element 55h will strike wall 36 at an angle to cause a turning movement about the axis of Ithe latch member. The inertia ofthe closing door readily overcomes the spring force exerted at convex face 67 to permit rotation of the latch member. In latched posi- -tion the spring force exerted `at face 68 is sufiicient to prevent rebound of the door just after closing.
Movement of the door away from the latch strike member will cause the rotary latch member to rotate in an opposite direction, overcoming the spring force at face 68 and automatically releasing the latch member Vfrom the latch strike member. Thus actuating means in the form of a handle or the like is not required for causing the latch mechanism to latch or unlatch. The lock device 7G provides a means for preventing rotation of the rotary latch member in unlatching direction so `as to cause locking of the latch mechanism to prevent opening of the door.
It will also be apparent tothose skilled in the art that the spring means 62 serves several functions which gives advantages to the latch mechanism of this invention. The spring means 62 is so positioned with its spaced convex faces in cooperable engagement with a latch element that the rotary latch member is properly positioned for proper striking engagement with the latch strike member. Upon such engagement, the spring means 62 yields resiliently to rotation of the latch member and thus cushions partially movement of the door into its nal closed position. It should also be noted. that the spring means 62 is quite simply and effectively secured and assembled to the latch casing by means of the center spring-retaining tabs or llanges provided on each matching case portion.
It is important to note that the latch member 54 i11- cludes an element (55a) disposed for latching engagement with the strike wall, a second element (55h) for sensing, striking, and causing response of the latch member to the presence of the strike member, and a third element or elements (55C, 55d) having cooperable contact with a spring means for positioning and biasing the latch member. It will be understood that the spring `section may be differently configured so as to cooperate with one latch element to position and bias the latch member as described above.
It may also be noted that strike wall 36 lies above and in the same plane as the axis of rotation of the latch member when the door is closed. Thus when lock device 70 is in locked position, upward movement or jimmying of the door to attempt to remove the door from the door frame is positively prevented by wall 36.
In the modification of this invention shown in FIGS. 7 and 8, a latch member 54 may be pivotally mounted about an axis defined by ports 51 on a latch housing (not shown in FIGS. 7 and 8) as in th-e prior embodiment. Extending outwardly from a hub portion may be a plurality of latch elements; namely, a latch element 55a, a sensing or responsive strike element SSb, and a latch positioning element 55c. It will be noted that the elements 55a, 55'b, and 55c are generally angularly related in the same manner as the elements 55a, 55h, and 55e, of the prior embodiment.
Latch element 55a extends forwardly and may be curved slightly upwardly at its outer end so as to provide a strike Wall engagement portion 82 adapted to contact 7 a vstrike wall 36' as shown in FIG. 8. In approach position, portion 82 is spaced below the bottom edge of strike wall 36 so as to pass beneath and to permit Contact of the outer surface of the strike wall by the sensing strike element 55b. The strike element 55'!) in this example is disposed generally at an angle of 60 to a horizontal plane passing through the axis of the hub di? and may include a curved or rounded end surface 34 adapted tot Strike the wall 36'. It may be noted that the strike element 55'b and the latch element SSa may be relatively closely spaced at their outer ends so that when the latch member is turned about its pivotal axis upon striking of wall 36 by strike element 55'!) wall 36 will be relatively closely embraced by the elements SS'a and 55b. The upper edge of the latch element SS'a may be concave in curvature so as to facilitate reception of the bottom portion of the strike wall 36' between the elements 55a and 55b.
The latch positioning element 550 extends generally rearwardly from hub .Sii and at its outer end may be provided with a spring engaging end portion 86 of gen# erally circular section. The end portion 86 may be a portion of a sphere if desired or it may be formed in any other manner to include a convex surface 87.
Spring means 8S may be mounted in the latch casing in a suitable manner and is provided a selected conguration from flat spring stock including spaced end pockets 89 adapted to receive and retain therein end por-tion 86 of the latch positioning element SSc. The end pockets 89 are spaced apart a selected distance to determine and limit turning of latch member 54.- about its pivotal axis into latched and unlatched position. Each end pocket 89 may be delincd by a spring end section 9i) serving to prevent movement of element 55's beyond the pocket. Between spring end sections 9o may be an interconnecting convex spring center section 9i, said section 91 being resiliently yieldable to' permit movement of end portion 86 of element SS'c between pockets 39. The resilient yieldability of center section 91 serves to urge the spring engagement portion 86 positively into either one or the other of said pockets and thus positively maintains latch member 54 in latched or unlatched position. A locking mechanism for latch member Sl'pis not shown in the drawings although it will be readily ,understood that lock means 7i) may be associated with latch member 4545' so as to act as a stop for turning the latch member S4 in an uplatching direction. It is understood that lock element 72 may cooperate with any one of the latch elements 55q, 5.5b, or 550.
Operation of the .modification of the latch means shown in FGS. 7, 8 is virtually the same asv that described for the iirst* embodiment of this invention and the latch elements SS'a, SSb, and 550 function and operate in virtually the same manner as the corresponding latch elements described in the prior embodiment.
It will be readily understood by those skilled in the rart that numerous modifications and changes may be madein the latch mechanism shown above, and all such changes and modiiications coming within the scope of the appended claims `are embraced thereby. y
1l. In a latch assembly-for' a sliding door including a stile provided with a door pull and a. rotary latch mem- 'b'ertherewithin having spaced latch elements, the combination of: recessl means provided by the stile and the door pull; and a pivotally mounted lock member within the recess means and provided with a laterally extending lock portionV extending into said stile for cooperable engagement with the' llatch elements, external lock-actuatingfportions extending away from said stile and along a surface of *saidy door pull, said lock-actuating portions being angularly arranged with respect to each other and saidpiill servingy as positioning means for said actuating params; p A
2. A self-latching, sel-releasable latching device for a sliding door including in combination: a latch casing having a front latch opening; a pivoted latch member carried by the casing with its pivotal axis lying perpendicular to the direction of movement `of the sliding door and provided with a plurality of latch elements including a iirst element to respond to a strike plate, a second element to cooperate with a spring member, and a third element for latching engagement with the strike plate, each having an outwardly directed engagement face; a spring member carried by said latch casing and having an engagement portion provided with spaced convex face portions engageable with said second latch element; whereby said latch member is turned in one direction against said spring member by Contact of said rst element with the strike plate to provide latched engagement of said third latch element with an associated strike plate and to rotate in the opposite direction against said spring member to release .said third latch element from such strike plate; and lock means :for said latch member, said lock means being provided with an internal locking element movable between adjacent latch elements, and external finger engagement portions on said locking means disposed in angular relation. p
3. A latching device as stated in claim 2 wherein said finger engagement portions are adapted to selectively seat against a surface of an associated door element.
4. A self-latching, self-releasing latch mechanism for a sliding panel cooperable with a door frame including a latch strike wall, comprising: a latch member mounted on the sliding panel for rotation about an axis and provided with a forwardly extending latch element, a sensing latch element angularly spaced from said iirst latch element and adapted to strike said strike wall to cause turning of said latch member; and means for resiliently holding said latch member in either latched or unlatched position, said means including a rearwardly extending latch positioning element on said latch member and spring means cooperable with said latch positioning element, said spring means including spaced spring pockets to receive said latch positioning element whereby said latch element is releasably held in either latched or unlatched position. i
5. A self-latching, self-releasable latching device for a sliding door including in combination: a latch casing having a front latch opening; a pivoted latch member carried by the casing with its pivotal axis lying perpendicular to the direction of movement of the sliding door and provided with ya plurality of latch elements including a irst element to respond toV a strike plate, a second element to cooperate with a spring means, and a third element for latching engagement with the strike plate, each element having an outwardly facing convex end surface; a spring means carried by the latch casing and having spaced convex face portions engageable with said lsecond latch element whereby said latch member is turned in 'one direction against said spring means by contact of said first element with the strike plate to provide latched engagement of said third latch element with an associated strike plate and to rotate in the opposite direction against said spring means to release said third latch element from such a strike plate; and a lock means provided with an internal locking Velement movable between adjacent latch elements and external fingerA engagement means on said lock means. l s I p 6. A latch mechanism for a sliding panel construction including a latch strike wall comprising: a latch member mounted on the sliding panel for movement about an axis, said latch member including a plurality of circumlaxially spaced elements including a strike wall sensing latch element disposed with respect Yto the strike wall to cause turning of the latch member upon striking the strike wall, a locking latchelement spaced from said sensing latch element and adapted to engage the strike wall in latching relation, said plurality of elements also including a latch positioning element provided with an engagement surface; spring biased means cooperable with said latch positioning element and including spaced surface portions to selectively engage said engagement surface on said latch positioning element to springload said latch member in both latched and unlatched positions; and lock means on the sliding panel having an internal locking portion movable between adjacent elements of Asaid plurality of elements.
References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Austria Ian. 10, 1900