US2132127A - Convertible stapling implement - Google Patents

Description

Get 4, 193. F. POLZER CONVERTIBLE STAPLING IMPLEMENT 2 Sheets-Sheet 1 Filed May 23, 1936 INVENTOR x ATTORNEY Filed May 25, 1936 2 Sheets-Sheet 2 INVETOR ATTORNEY Patented Oct. 4, 1938 2,132,127

UNITED STATES PATENT OFFIQE CONVERTIBLE STAPLING IDIPLEMENT Fridolin Polzer, Norwalk, Conn., assignor to The E. H. Hotchkiss Company, Norwalk, Conn., a corporation of Connecticut Application May 23, 1936, Serial No. 81,389

19 Claims. (01. 13)

This invention relates to portable implements pling head so that the momentum of the swingin for setting staples into work to be fastened base shall not cause it to be flung into contact thereby, and particularly concerns implements with the wrist of the user whose hand is graspfor this purpose which may readily be converted ing the stapling head.

5 from a form that is suited to driving staples Another object is to provide a self-acting through materials and clinching them, toa form latch adapted positively to hold the base and suited for use as a staple tacking or nailing imstapling head in predetermined oppositely eX- plement. tending relationship with suflicient rigidity to In paper fastening staplers designed for use make the base usable as a handle forv supporting on a deskor table top it is common to provide and maneuvering the stapling head. Preferably 10 a base supporting a staple clinching anvil and this latch is made readily releasable for conto provide a superimposed staple feeding and veniently restoring the base and stapling head driving head including an arm-like portion cornto folded relationship. prising a staple storing and feeding magazine. A further object is to provide such fastening Such arm-like portion of the stapling head is means and latch in forms which shall in no way 15 pivotally connected to the base so that the head interfere with the usual operating parts of a may have a swinging movement to different staple feeding and driving head, nor make more heights above the base carried anvil. For addifi'icult the reloading of the same with a fresh mitting sheets to be fastened together, the head supply of staples.

is normally poised in a position slightly spaced A related object is so to incorporate the fas- 20 above the base carried anvil. tening and locking means within the structure One object of the present improvements is to of the implement that the mechanical parts comprovide in an implement having some or all prising such means 'will be inconspicuous or inof the characteristics described, a stapling head visible to the eyes of theuser when the impleand base which upon suitable occasion may be ment stands in ordinary position upon a desk or 25 swung widely open from a folded relationship table top. to oppositely extending relationship and auto- A still further object is to locate as many as matically and positively locked therein, so that possible of the parts of the fastening means the base becomes usable as a handle for supand of the lockingmeans at a common point porting and maneuvering the stapling head to upon the base and to make use of a common 30 'place it in desired position against any body or part or parts in the construction of both the faswork into which a staple is to be driven. toning means and the locking means whereby Another object is to provide an improved fasthe number of parts required is minimized and tening means for yieldingly maintaining the the manufacture thereof made simpler and less stapling head within a range of positions of costly. 35 varying elevation above the base carried anvil, These and other objects will become clear from this range of positions comprising the ordinary the following description in which reference is folded relationship of the stapling head to the had to the accompanying drawings. In the base. The fastening means is preferably of drawings:

40. such nature that it exerts sufficient cling to Fig. l is a plan view of a stapling implement 40 support the weight of the base when the impleembodying the present improvements ment is bodily lifted by means of its stapling Fig. 2 is a side elevation of the implement in head in the ordinary action of moving it about which the broken lines indicate relatively elei s use p a desk r table op. vated and depressed positions of the stapling 4-5 Another object is to provide sufficient yield head, and the dot-dash lines represent a users in the holding construction of the fastening hand grasping the'implement in a natural manmeans referred to so that an abnormally abrupt nor for lifting it from a table surface.

yanking of the stapling head upwardly shall Fig. 3 is an endwise view looking from the right suffice to release the fastening means and disat Fig. 2.

; place the head from its folded relationship to Fig. 4 is drawn on a much reduced scale and 50 the base in consequence of the weight or inertia shows the implement lifted by the hand of the 0f the latter. user and its base swung to an open or oppo- Another object is to provide means positively sitely extending position in relation to the stato limit the resulting angle of swing" of the base pling head. .5 7; in its separating movement relative to the sta- Fig. 5 is drawn on the same scale as Fig. 4

and shows the stapling head applied directly against the top surface of a body into which staples are to be driven. One hand of the user is represented as grasping the base of the implement for use as a handle.

Fig. 6 is a much enlarged view of the pivotally connected ends of the base and stapling head taken in central lengthwise section on the plane 6-6 in Fig. 1, looking in the direction of the arrows. Broken lines represent a different position of the stapling head in partially spread relationship to the base. The position of the staple feeding parts differs from that in Fig. 1 by showing the staple storing magazine freshlyloaded with a full supply of staples.

Fig. '7 is drawn on the same scale and shows the pivotally connected ends of the base and stapling head interlocked in their oppositely extending relationship.

Fig. 8 is a View taken in cross section on the plane 88 in Fig. 6 looking in the direction of being partly broken away more fully to expose the spring;

Fig. 10 is a still further enlarged view of the spring fastener cup shown partly in section as the cup appears looking downwardly from the planes ||l| in'Fig. 8.

Fig. 11 shows a modification of shape which may be given to the right end of the base in Fig. 2

r to guard against accidental pinching of the users hands or clothing in the relative swinging move ment of the stapling head and base.

l0 designates the stapling head as a whole includingits horizontally extending arm' portion pivotally connected to the base II by the hinge screw l2. The staple driving and automatic staple feeding mechanism is, in large part, concealed within the casing of the stapling head if! and may be operated by the depressible hammer top l3. A staple expelling orifice (not shown) gives outlet to one staple at a time at a point in the stapling head just above the base carried anvil M at each downward stroke of thehammer l3, the anvil serving in a well known way to clinch the entering ends of the staple after they have pierced the material to be fastened.

The horizontal arm portion of stapling head 1!] contains a magazine chamber for storing staples and provides a track upon which the staples may be advanced toward the left in Fig. .6 by the;con-

stant tension in a coiled bandspring whose knob-like terminal l6 removably-engages a stem upstanding from the. push slide la'which' in cross section is of U-shape to accord with the inverted U-shaped staples l9 andwhichrides on the same tracks 2|] therewith.

' The tracksv 29 are provided by a channeled bar 2| which is made fast to the long, narrow underwall 22 of the stapling head casing in any suitable way, as-byrivcts or spot welding, not shown, while the channel in bar 2| is availed of to contain and render inconspicuous certain parts which I have provided to comprise a novelly constructed and novelly functioning fastening means operative between the stapling head and the base. For fuller details of the main parts'of the implement, which have been briefly described, reference may be had to my co-pending application,

Serial No. 22,130, filed May 18, 1935,: nowPatent Number2,11'7,743, granted May 17; 1938.

as Fig. 6-

With particular reference to Figs. 6 to inclusive, the bed of the channeled bar 2| together with the underlying casing wall 22 are pierced to form a hole having a deep counterbore 23 opening upwardly through the floor of bar 2| in which hole is slidably carried the fastener plunger or plug 24. This plunger has a head 25 of larger diameter than its shank and of such thickness that when the top of head 25 is flush with the floor of bar 2|, suitable space exists between head 25 and the bottom of counterbore 23 to serve a purpose hereinafter explained. Plunger 24 is yieldingly restrained from rising above the floor of bar 2| by the leaf spring 26 normally maintained flat against the floor of bar 2| by a holding screw 21 having threaded engagement with the bed of bar 2| and a portion of the underwall 22 of the stapling head casing.

As most clearly shown in Figs. 6 and 8, the base H is hollow and carries on its upper surface and in position to register with plunger 24, a spring clip or socket-like device having resiliently biased elements in part defining the mouth there-,

of herein illustrated as the spring fastener cup 28. the head of ascrew 29 whose shank penetrates a closely fitting aperture in the bottomof the cup and has threaded engagement with a hole through the top wall of the base, projecting considerably therebelow to serve as constraining guide for cer- This cup is secured in place on the base by,

tain additional locking parts next to be described.

The cooperative formations which are given respectively to the bottom end of plunger 24 and to the receiving rimof cup 28 are most clearly shown in Fig. 6rwhere these parts are shown engaged, while Fig. 10 shows inenlarged detail the nature of suitable slots 44 with which the rim and upright wall of the cup may be provided to permit resiliently opposed spreading of the rim lips of the cup for admitting the plunger to the interior of the cup and thereafter yieldingly resisting its withdrawal therefrom.

The right end of base contains an aperture 30 Fig. 9 flanked by, vertical walls. The lateral walls 3| and 32 are substantially beneath the lugs 33 and 34 respectively which project above the base H to support the hinge screw I2 and to guide the end of the stapling head which is pivoted therebetween. A flat sided recess is thereby formed into which the extreme right end of the stapling head may swing as indicated by broken lines in Fig. 6. The third wall 35 is in transverse relation to the base and closes the left end of aperture 30 being continuous with walls 3| and 32.

Against the bottomsurface of the top wall of the base, a latch 36.is constrained-to slide and has a downwardly turned ear 3'! for manipulating it. Latch 36 also has an elongated slot 38 engaged by the cup retaining screw 29 and its right extremity projectsthrough a slot 39 in wall 35 and into the recess of aperture 30 of the base. As clearly shown in Figs. 6 and 9, slot 38 is also engaged at its right end by the free terminal of a Wire spring 40, several turns of which are coiled about the cup holding screw 29 and retained thereupon by the nut 4| which has threaded engagement with screw 29 and may be secured thereon by peaning over the end of the screw or in any suitable way. The formation given to spring 40 between its mounting screw 29 and its point of engagement with the end of slot 38 constantly urges latch 36 toward the right in Figs. 6, '7 and 9 to an extent limited by the engagement of the left end of slot 38 with screw 29. The coiled body of spring 40 also helps to maintain latch 36 in slidable contact with the upper wall of the base throughout the length of the latch. As will appear hereinafter, the right end of latch 36 may be somewhat chamfered to facilitate its co-action with the corner 42 of the stapling head extremity when these portions of the structure come in contact as indicated bybroken lines in Fig. 6. Fig. 11 shows modified shape which may be given to the lugs 33 and 34' at the hinge end of the base to preclude the possibility of any part of a persons hand or clothing being caught or pinched by the shear-like action of the extremities of the base and stapling head which project to the right of the hinge screw I 2 in Fig. 2.

The operation of my improved stapler is as follows. In the folded relationship of the stapling head it and the base H, the stapling head is normally poised in its position shown by full lines in Figs. 2 and 6. In this position the weight of the stapling head at the left of the hinge screw i2 is supported by the slidable plunger 24 whose head 25 is prevented from projecting above the counterbore 23 by the resilient strength of the leaf spring 26 so that it may be said that the weight of the stapling head is borne by the flexural resistance of this spring. Papers which are to be fastened together may be inserted between the stapling head and the anvil M which are kept suitably separated for this purpose by the before mentioned parts. When the hammer top 53 is forced downwardly to drive a staple, the stapling head will swing downwardly against the sheets of paper and overcome the resistance of spring 25 which will thereby be caused to yield to its broken line position'i'n Fig. 6 thus permitting the plunger head 25 to project temporarily above the floor of the channeled bar 2|. This position of the stapling head is indicated by broken lines It!" in Fig. 2. v y

If the thickness of the papers or work to be inserted between stapling head It and the base anvil l exceeds the normal space therebetween shown in full lines in Fig. 2, the stapling head may be manually lifted to its position rep-resented by broken lines Ill". This will be freely permitted without lifting plunger 24 out of the spring fastener cup 28 because of the lost motion or play between the plunger head 25 and-the bottom of counterbore 23.

Thus the engagement of plunger 24 with cup 23 maintains a folded relationship of the stapling head If and base i I in which relationship the stapling head may perform its work of feeding and driving staples in any position within a range whose bottom position is that designated as ill and whose top position is that designated as It in Fig. 2.

The resistance of the spring fastener cup 28 to the withdrawal of plunger 24 therefrom is preferably such that an excessively abrupt, upward yank of the stapling head by the hand of the user shown in Fig. 2 will suffice to separate the plunger from the cup. If lifted clear of the table 43, the base will consequently swing very abruptly to a wide open or oppositely extending relationship as shown in Fig. 4, and if stops were not provided to prevent it, the base might continue to swing far enough to strike the wrist or arm of the user. This is prevented, however, as is most clearly shown in Fig. '7, when the extreme end of the channeled bar 2i swings into abutting contact with the base wall 35. To reach this position the end of bar 2i in swinging from its unbroken line position in Fig. 6 to its full line position in Fig. 7 about the hinge screw i2, en-

gages and forces toward the left, the right extremity of latch 36 against the tension in spring 40. When the fully spread relationship shown in Figs. 4 and '7 is attained, latch 36 quickly snaps toward the right in Figs. 6, '7 and 9 thus imprisoning the end of bar 2| against withdrawal from its position shown in Fig. 7. Such latch acts to prevent'rebound of the base structure following its abutting impactagainst the head structure in the position of parts shown in Fig; '7 wherein the base structure has been abruptly flung from its detent held folded relationship to the base, as in Fig. 2, to a position oppositely extending therefrom, as in Fig. 4. This prevents possible harm to the hand of the user or damage to any surface or object on a desk from which the implement has been abruptly lifted. Without such latch or equivalent positive catch means, the base structure would be left free to dangle and swing about its pivotal connection to the head structure violently and without control when the latter is yanked upwardly. In this locked and oppositely extending relationship of the stapling head and base, the base extends in approximate alignment with the staple magazine or arm portion of the head and is well adapted to serve as a handle which maybe grasped by the hand of the user as represented in Fig. 5 for maneuvering and placing the stapling head in position to tack or nail a staple into the body of any desired object such as the table top 43 to which a sheet of drawing paper, for example,-may thereby be fastened.

When it is desired to release the base and stapling head from their oppositely extending relationship shown in Figs. 4, 5 and 7, the latch 35 is conveniently pulled toward the left by its downturned ear 3! most clearly shown in Fig. 6, after which and when restored to folded relationship, the plunger 24 will. re-enter the spring fastener cup 28 owing to the force of leaf spring 2% exerting enough. pressure against the plunger head 25 to force-the split rim of cup 28 to expand circumferentially and admit the bottom end of the plunger to the interior of the cup. However, the grasp of the cup 28 upon the plunger exerts enough cling to cause the base to be lifted when the stapling head is lifted in an ordinary manner as for picking up the implement and otherwise handling it as a portable device for desk use.

While, within the scope of my invention, the fastening means for holding the base and head in folded relationship, and the locking means for holding these same parts in oppositely extending relationship, may assume various and sundry forms which will be-suggested to workers in the art bythe disclosure hereof, it will be appreciated that the particular forms which I have chosen to illustrate involve very few parts additional to those commonly found in a stapler not equipped with my present improvements. Also I have incorporated the parts within the structure of a conventional stapler in such manner that they are relatively large and strong and free from the requirement of extreme accuracy of dimension in their cooperative relationship. The parts here- 6 ments herein disclosed but intend the language of the following claims to include all fair equivalents of the constructions described and illustrated herein and all substitutes for and depar-' tures from the disclosure hereof which would be suggested thereby to others skilled in the art.

I claim: I

1. In a stapling implement, the combination with an anvil base structure and a superimposed stapling head structure pivotally connected to and overhanging said base structure, of means yieldingly to maintain the head structure poised in a definite position spaced above the base structure embodying a resilient device defining a socket entrance and carried by one of said structures and a cooperatively formed plunger carried by and in movable relation to the other of said structures andprojecting, therefrom in a manner to support the weight of the head structure, positive means to limit the movement of said plunger in one direction relative to the structure which carries it, and resilient means constructed and arranged to oppose movement of said plunger in the opposite direction relative to the structure which carries it, with a resistive force greater than the force with which said plunger is biased I downwardly by the Weight of said headstructure'.

2. In a stapling implement, the combination with an anvil base structureand a superimposed stapling head structure pivotally connected to and overhanging said base structure, of means to maintain the head structure resiliently poised in a position definitely spaced above the base structure embodying a plunger slidably mounted in the head structure and projecting therebelow to contact with the base structure in a manner to support said head structure in its said poised position, and a spring constructed and arranged to urge said plunger to project a predetermined extent below the head structure when the latter is supported in its said poised position and to be yieldable to permit on occasion manually forced downward movement of the head' structure toward the base structure from said poised position.

3. In a stapling implement, the combination with an anvil base structure and a superimposed stapling head structure pivotally connected to and overhanging said base structure, of means normally to confine the head structure to a definite range of separating movement relative to the base structure embodying a plunger mounted in movable relation to the head structure in a manner to have lost motion transverse said head structure in a downward direction toward the underlying base structure, said plunger projecting below the head structure to contact with the base structure, and a catch device carried by the base structure in position to be engaged by said plunger and cooperatively formed and arranged to cling to said plunger.

4. In a stapling implement including a hollow base and a stapling head pivotally connected thereto,mechanism cooperative with said head for holding the latter in a plurality of positions relative to said base embodying in combination with a roof wall of the hollow base, a snap fastener cup mounted on the base, a screw having a cup retaining head inside the cup and having a shank penetrating the roof wall of the base and projecting therebelow, a latch slidably guided by the projecting shank of said screw below the roof Wall of the base, and means to constrain said latch to adefinite path of sliding movement relative to said shank.

5. In a portable stapling implement, the combination with a stapling head structure and an anvil base structure pivotally connected thereto in a manner to be flung abruptly from a folded relationship to an oppositely extending relationship to said head structure, of a set of interengageable detent devices carried in part by each of said structures and, adapted to perform a quick releasing action, said devices cooperating when engaged to hold said base structure in folded relation to said head structure with sufficient cling to enable both structures to be gentl'y lifted in unison by use of the head structure as a handle but with insufficient cling to maintain said structures in folded relationship when the headstructure is yanked upwardly with intended abruptness, abutting means carried in part by each of said structures and disposed to arrest swinging movement of the base structure when it has reached approximately an oppositely extending relationship to the head structure, and a manually retractable spring urged latch constructed and arranged automatically to lock and positively retain said base structure in its said oppositely extending relationship to the head structure when said abutting means arrive in contact at the end of the abrupt swinging movement of the base structure relative to the head structure.

6. In a stapling implement, the combination with an anvil base structure and a longitudinally superimposed stapling head structure pivotally connected to said'base structure, of means to hold said head structure poised above the base structure and'to resist the swinging separation of said structures including a catch carried by the base structure and a projecting member carried by the head structure and swingable therewith in a path of movement to engage with said catch, the said member being mounted to have a lost motion relative to said head structure in the formed plug carried by the other structure in position to enter said mouth and to engage with and be yieldingly retained by said lip.

8. In a stapling implement, the combination set forth in claim 7 in Which the said plug is loosely mounted on the said other structure in a manner to yield in divers lateral directions for centralizing itself with the said mouth of the socket-like device upon entering and leaving the same.

9. In a portable stapling implement, the combination with a stapling head structure and an anvil base structure pivotally interconnected to be flung abruptly from a folded relationship to an opened relationship, of a resilient socket device carried by one of said structures and a cooperatively engaging plug carried by the other structure and adapted to perform a clingin and quick releasing action respectively to hold said base structure in folded relation to said head structure when the head structure is used as a handle for lifting the base structure and to permit the release of said base structure from said head structure when the headstructure is yanked upwardly with intended extraordinary abruptness, abutting means carried in part by each of saidstructures and disposed to arrest swinging movement of the base structure when it has reached a predetermined open relationship to the head structure, and a manually retractable spring urged latch constructed and arranged automatically to lock and positively retain said base structure in its said open relationship to the head structure when the said abutting means arrive in contact at the end of the abrupt opening movement of the base structure relative to the head structure. t

10. In a portable stapling impl'ementincluding a base structure and a superimposed stapling head structure pivotally interconnected ina manner to swing apart for receiving therebetween the work to be stapled, detent means carried by one of said structures, a cooperative detent member mounted on the other of said structures in a manner to be movable relative thereto and to project therefrom in a direction to engage with said detent means thereby to act as a structure connecting spacer for holding the head structure at a normal distance above the base structure, resilient means constructed and arranged to bias said detent member in a manner to oppose movement of said head structure nearer to said base structure than its said normal distance therefrom with sufiicient strength to uphold the weight of the head structure without yielding thereto, and means to permit said member to be relieved from the bias of said resilient means when the head structure is separated farther than its said normal distance from said base structure.

11. In a portable stapling implement, the combination with an elongated stapling head structure and an elongated anvil base structure pivotally interconnected near'their ends to permit relative swinging of said structures between a folded relationship and an oppositely extending relationship, of abuttable surfaces rigidly carried respectively by each of said structures in positions to meet and thereby positively limit relative movement of said structures in one direction when said structures are in said oppositely extending relationship, a locking surface rigidly carried by one of said structures, and a rigid spring biased latch bolt carried by the other structure and positively guided for movement relative thereto toward and away from a position to meet with said locking surface and thereby positively limit movement of said structures in the opposite relative direction when said structures are in said oppositely extending relationship, whereby all of said surfaces and said latch bolt cooperate to condition the base structure for use as a handle positively interlocked with the head structure for rigidly supporting and maneuvering the stapling head at a maximum distance from the hand of the user.

12. In a stapling implement, the combination set forth in claim 6 in which the said stapling head structure contains an aperture shaped to form a shoulder intermediate the ends thereof and the said projecting member is shaped to form a shank portion slideably guided lengthwise in said aperture and a shoulder engageable with said shoulder in the aperture thereby to limit lengthwise movement of said projecting member in one direction.

13. In a stapling implement, the combination set forth in claim 6 in which the said stapling head structure contains a round hole therethrough having a counterbore at one end, and the said projecting member comprises a cylindrical body slideably guided lengthwise in said hole and enlarged at one-end to form a head occupying said counterboren l4. Ina staplingimplement, the combination set forth in claim 6 in which the said stapling head structure contains a round hole extending therethrough having a counterbore at one end,

and thesaid projecting member comprises a cylindrical body slideably guided lengthwise in said hole and enlarged at one end to form a head 00- cupying said counterbore and circumferentially grooved near the other end for effecting holding engagement of said projecting member with said catch,

circumferentially grooved terminal portion D TQ- jecting from one end of said aperture to enter the said mouth of the socketlike device, together with means yieldably held on said plug carrying structure in a position to overlie the other end of said aperture and be engaged by said member.

16. In a stapling implement, the combination set forth in claim 7, in which the said structure which carries the said plug contains an aperture opening through opposite faces thereof and a counterbore enlarging said aperture at one face of the said structure, and the said plug comprises a member having a shank portion slideablyguided in said aperture, a head portion occupying said counterbore and a circumferentially grooved portion projecting from said aperture in a position to enter the said mouth of the socket-like device, together with yieldable means secured on the said plug-carrying structure in a position to overlie said counterbore and normally confine said head portion of the plug member therewithin.

17. In a stapling implement including an elongated stapling head and an elongated underlying anvil base pivotally connected together for relative swinging movement between-a codirectional relationship and an extended relationship, means for converting said implement by single handed operation from a condition for use to clinch staples to a condition for use to tack staples including in combination with said head and base, detent means constructed and arranged therebetween to cause said base and head initially to cling together in said codirectional relationship when said head is yanked abruptly upward, and immediately thereupon suddenly and automatically to free said base from said head in a manner to set up kinetic inertia in said base causing the latter to swing abruptly about its pivotal connection to said head and into extended relation to the latter while said head is suspended from the hand of the operator, abuttable surfaces carried by said base and head in positions to engage and limit the swinging of said base relative to said head, and catch means constructed and arranged positively to resist rebound movement of said base relative to said head after the said surfaces have contacted, thereby to hold said base positively locked in extended relation to said head so that the base may thereafter be grasped in a portion remote from said head and thereby maneuvered for shifting said head to desired locations against the work to be stapled.

18. A portable stapling implement normally conditioned for clinching staples against a self contained anvil and adapted through single handed actuation by the operator. to be instantaneously converted to a. condition for tacking unclinched staples into work, embodying stapling head and anvil base structures pivotally connected for relative swinging movement, selfclinging means carried in part by companion portions of each of said structures constructed and arranged suddenly and automatically to disengage responsive to a smart upward yank imparted to said stapling head structure by a single hand of the operator in consequence of the opposing weight of said anvil base, and self-interlocking means including solid abutments carried respectively by each of said structures in positions to engage and positively limit relative swinging of said structures in one direction resulting from said upward yank on the stapling head structure and including a movable rigid member arranged tobe spring biased in one direction and manually retractable in the opposite direction constructed and arranged automatically to prevent swinging rebound of said structures after said abutments have engaged.

19. In a stapling implement including a hollow base having a roof wall, a stapling headpivotally connected to said base and separate detent parts carried by said stapling head in a manner; to be caught and held on respectively different occasions in respectively difierent positions of said stapling head relative to said base, mechanism cooperative with said detent parts for separately catching and holding each of said detent parts on different occasions embodying in combination, a spring clip device mounted on the top of said base in a manner to engage with one of said-detent parts, a screw having a head inside said clip for securing the latter to said roof wall and having a shank penetrating said wall and projecting therebelow, and a latch slidablyguided by the projecting shank of said screw in a path of movement adjacent and parallel to the under surface of said roof wall into and out of a position to engage with the other of said separate detent parts, and additional means to constrain said latch to: its said path of movement. 7

FRIDOLIN POLZER.

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