US2531985A

US2531985A - Wire stitching mechanism

Info

Publication number: US2531985A
Application number: US128753A
Authority: US
Inventors: Nasmith John Irving
Original assignee: Vickers Armstrongs Ltd
Current assignee: Vinters Armstrongs Ltd
Priority date: 1948-11-26
Filing date: 1949-11-22
Publication date: 1950-11-28
Anticipated expiration: 1967-11-28

Description

Nov. 28, 1950 I J. l. NAsMlTH 2,531,985

WIRE STITCHING MECHANISM Filed Nov. 22, 1949 5 SheetS-Sheet/l l 50a .71261524 i i I 50h? I l f 1 w E@ ,7 YA i i la l@ l I i I a a l l f l5 I? @I I :i4/22 i L) i F C D- 7a i E I 7b I l l fd) f f 'i l n U r 10a 6 Z4 Zlfb @al 6a j/yf/VfaL v l JH/l Rv/Ncr/Va/n/f/r xg! I x ,4a EN f:

Nov. 28, 1950 J. l. NAsMlTl-l 2,531,985

WIRE STITCHING MECHANISM Filed Nov. 22, 1949 5 Sheets-Sheet 5 Nov. 28, 1950 V J. l. NAsMlTl-l 2,531,985

WIRE STITCHING MECHANISM Filed Nov. 22, 1949 5 Sheets-Sheet 4 Nov. 28, 1950 J. l. NAsMn-H WIRE STITCHING MECHANISM Filed Nov. 22, 1949 5 Sheets-Sheet 5 Patented Nov. Z8, 1950 UNITED STATES PATENT OFFICE WIRE STITCHING MECHANIS-M John Irving Nasmith, London, England, assigner to Vickers-Armstrongs Limited, London, England, a British company Application November 22, 1949, Serial No. 128,753 In Great Britain November 26, 1948 Claims.

The' invention relates to improvements in wire stitching mechanism and more particularly tov the means of supporting and buttressing the staple formed in the` operation oi wire stitching mechanism, during the' time that it is being driven intov and is penetrating the material being operate'd upon.

In known wire stitching mechanism this support is given externally by the uper staple forming element, sometimescalled the outside former, and internally by a shoe over which the staple is' straddled and which is progressively removed' from between the staple legs asI the staple is driven into and penetrates the material being stitched or stapled.

The external support is eiiicientl provided the forming element is given adequate dimensions, but although the internal supporting shoe can be given a' variety of shapes and mechanically controlled motions, no known combinations of these can give thev desirable amount of support at all stages of penetration ofthe staple into the work, as referred to in more detail in the following de'- scription'. n

It is the object of the present invention to provide internal staple supporting means not sub'-, ject to such limitation and to give an improved degree of support throughout the staple driving operation.

To atta-in this object the internal' supporting means comprises two parts in the form of separately mounted and` mechanically controlled elements working in conjunction with each other as a staplel supporting unit, and by this construction the internal support given to the staple' can be made much' more eiiective and' uni-form in ac# tion.

In the further description, the portions of the staple driven into the work are referred; to as the legs of the' staple, and the' portion joining these legs at one end, as the crown` of the staple.

Assuming completely eiiicient supporting means, the theoretical limit of penetration of any given staple is not reached until either plastic flow oi the' staplematerial occurs, or until there'- sista-nce to penetration of the materiall operated upon is greater than thev support the surrounding material can give to' thestaple legs, which then crumple' or' otherwise deflect in the material.

In known practice fai-lineA toY penetrateY occurs before either of these stages is reached, due to the staple crown bending and forcing out the staple supporting means. In accordancewith the invention, by providing the staple support in the form of two separately mounted and controlled but co-operating portions, the theoretical limit of penetration can bemuch more closely approached. The improved degree of control and support of the staple is achieved by supporting the staple crown normally or substantially normally throughout almost the whole of the drivn ing operation and preferably so that the supporting means cannot be forced out of position ahead of the corresponding stage of penetration.

For practical reasons it may be desirable in diiferent cases to vary the construction to suit the conditions to be satisfied without departing from the' principle' oi providing the staple supporting means in the iorm of two' co-acting elements, the oneV to provide adequate positive or spring controlled support for the crown of the staple, and the other functioning only to support the legs thereof, or, in the case of spring controlled supports, the support of the staple may be shared between the leg support and the crown support according to the stage of penetration. It may bel arranged that the motion of one of the supporting elements is positively controlled for a greater part of the driving operation, after which the positive control is removed and the najor portion of the supporting action is taken over by the other supporting element which is spring controlled.

In the' case of stapling or stabbing, the force of penetration-rises' to the required value during the early stages of driving and then remains substantially constant. As the length of the strut formed by the undriven portion of the staple legs diminishes, the tendency' for the crown to collapse diminishes als'o. In theA case of stitching the conditions of penetration are similar and, just before breaking through, the load tends to rise and falls toa small amount as soon as the points of the staple cut their Way through the last layers. In either' case therefore if the crown is fully supported up to a shortdis'tance before completion of driving, the tendency of the crownv to collapse has diminished to such an extent as no longer to cause any diiiiculty.

The' mechanicall detail employed in carrying out the invention can be varied according to the type of stitching mechanism to which it is applied, and, as will appear from the subsequent description, the invention may be applied to the type of machine where the manipulative space above the top level of the work when operated upon must be as large as practicable and in which it is therefore desirable that the maximum of support be given to the crown of the staple.

A particular form of construction with positive control of the staple supporting means during penetration will now be described in more detail with reference to the accompanying drawings.

In this construction the support for the crown of the staple is also used as a bending block or loop bar in conjunction with the outside former to bend the straight length of wire into a staple, and thus serves the dual purpose of an inside former during forming and of an internal crown support during driving of the staple. This dual purpose is not however an essential feature, and if desired the construction could be modified to use a separate inside forming element over which to bend the wire, for subsequent transfer to the crown support. Figures 1, and 9 to 14, are Ipart sectional elevations through the stitching head taken on a vertical plane through the common axes of the outside former and the driver and at right-angles to the plane of the formed staple.

The stationary parts of the stitching head framework, which support the movable elements, have been omitted from some of the figures and, where shown, these stationary parts are indicated only in so far as necessary for the purpose of illustrating the manner in which the invenn tion is performed.

Figure 1 is a sectional elevation through the stitching head showing the forming and driving elements in the uppermost position of rest before the commencement `of the staple forming and driving operations;

Figure 2 is an elevational view taken in the direction indicated by the line II-II of Figure l, with the front cover plate removed;

Figure 3 is an elevation view of the front cover r plate taken in the opposite direction to that of Figure 2 and showing the parts connected to the cover plate;

Figure 3A is a partial side elevation of the cover plate taken in the direction of arrow IIIA of Figure 3;

Figure 4 is a partial sectional side elevation of the stitching head taken in the direction of the arrow IV of Figure 2;

Figure 5 is a detail View of the outside former;

Figure 5A is a sectional view taken along the line VA--VA of Figure 5;

Figures 6, 7 and 8 are detail views showing separately the staple leg support, the staple crown support and the staple driver, respectively.

Figures 9 and l0 show successive stages in the staple forming operation;

Figures 11, 12 and 13 show successive stages in the staple driving operation; and

Figure 14 shows an initial stage in the return motion of the parts after the completion of driving.

Referring now to Figure 1, F is the stationary framework of the stitching head and C is the removable front cover plate, which together enclose the driver and the outside staple former and other elements to be described hereinafter. It will be understood that the driver and outside former are guided for vertical motion in the stitching head, this motion being derived from a v GOY rotating cam plate 30 in a manner already generally known and substantially as described in United States Patent No. 1,896,826, dated February 7, 1933, issued to J. I. Nasmith. The main drive does not form part of the present invention and is not therefore described in detail in the present specification.

X--X is a horizontal line indicating the level of the top of the work, the gap between this and the bottom of the elements being required for handling space.

l is the upper staple forming element, hereinafter also called the outside former, and Ic is a pin for a cam roller ld co-operating with a cam groove 3l formed in plate 30, whereby the desired vertical motion is imparted from a cam shaft le to the outside former.

By means forming no part of the present invention a length of wire w fed and cut off from the stock is brought into position over the foot of the crown support (to be described later) ready to be bent into a staple by the forming element. In the construction under consideration, as the space must be left free, both portions of the staple supporting means i. e. the element which supports the crown and that which supports the legs, must have a considerable vertical movement to close down to the work.

The mounting and action of the supporting element for the legs, hereinafter called the leg support, will now be described. This is a lever 3 pivoted at 2 in the upper end of the outside former, and its vertical motion is thus the same in amount and relative timing as the latter. The leg support is movable about the pivot 2 for insertion between the legs of the staple, and is normally held out of action by a spring Il buttressed and provided on the ouside former at 4a.

Upon rotation of the cam plate 30 in the direction indicated by arrow K in Figure 2, the outside forrner is urged downwardly from the position shown in Figure l, the lower ends of the former engaging and bending the wire wto form a staple over the foot of the crown support 6. On the down stroke of the outside former the leg support carried thereby moves downwards clear of the wire and the crown support until the outside former has bent the wire into a staple and begins to enclose the legs of the staple. A link eccentrically mounted at 32 in a cani projection Sila and pivotally connected to the upper end of the staple driver l, provides for the vertical motion of the driver upon rotation of the cam plate 30. AS downward motion of the staple former continues a projection 3a on the rear of the staple leg support strikes a plunger 5 (Figure 9) mounted in the iiXed head of the machine and pressed forward by a spring 5a, and, overcoming the force of the spring 4 holding the said support out of action, causes the latter to be rotated about its pivot and to be inserted between the legs w2 (Figure 10) of the staple to a position determined by a stop vface 3b (see Figure 9) on the inner side of the leg support contacting a vertical face l b of the outside former. The lower end 3d of the supporting element is now projecting through the staple and is held there (Figure 10), and is in the position to co-operate with the crown support during the driving of the staple. The outside former l has now come into Contact with the work W and the driver 'i into contact with the crown of the staple. The outside former remains in contact with the work until the staple has been completely driven into it, When the crown support moves downwards, as will be further 5l, described, it. forces: back. the leg supportY againstI the spring-loaded plun'ger'r in the stitching head untill the driving of the' staple is almost complete. The driving of. the staple and the mounting and construction of the crown support and they mannery of its cooperation with the leg support will now be morel fullydescribed.

The` crown` support is formed: asi al stem.'` 6,. normally in: a vertical position, carrying a: short hook-like foot 6av extending at right angles at' the lower end thereof,v this foot having an inclined face b shaped. to co-operate withA th'e front. face of the end 3d of the' leg; supporting element. At. its upper end the crown: support provided at either side withY guide pins 8' engaging vertical` slots 9 (Figure 3:) formed at either` sid-'e in the cover plate C enclosing' the head of the machine and' retaining the outside' staple formerv and the' staple driver therein. Also mounted in thisI cover plate is an eccentric pini Ill, normally withl its eccentricity vertical', and the eccentric' portion Ifila.V engages' the lower end of a slot IfI: on one: side of the crowny support and?, in conjunction with the aforesaid guide pins, holds? the stem 6V ofV the crown support in the' verticali position during the greaterl part of its motion. Tneg'uide pins; 82 at the upper end of the crown supporti are nor;-A mally held against the upper end' of the slots 9l by a vertical spring' I2, thus keeping the crown support in its uppermost position.

Also mounted in the cover plate is a transverse sliding pin t3' hereinafter also.l referred to as the upper looking pinA adapted to engage. a step I4 at the upp-er endI of the crown support. This pin serves positively to retain the crown' support in its uppermost position whilst the' outside former bends the wire into a staple over'the crown support (Figures 1 and 9), which. during this part ofthe working cycle ful-lls the function ofthe loop baro'r inside forrner'.4

The positive connection is released byr a. releasing pin I5, secured to the fronti face of theV outside forming element I. When this element has nearly completed its downward travel, thisA releasing pin strikes an inwardly projecting arm ISS` of a three-armed lever pivoted at Il' on. a fixed pin on the cover" plate, the lower arm I of which lever engagesI the upper locking pin I3, and the other arm I9- of which actsv as a stop against. the front of the cover plate whenl the Y locking pin. is in the` disengaged position. A light spring' 20' stretched between the lower arm of the' lever and' a xed pin 2| inthe cover plate,` swinging from one side to the other of the pivotfcentre' Il, retains the upper locking pin I'3 in the position to which it was last actuated. The lever arm I'I is actuated in the reverse. direction to rei-engage' the upper locking pin I3 with the stepy lill by aY corresponding striker pin 221 secured` lower down on the face of the outside former, this pinl conring intoaction when the outside formernears itsv uppermost position.

The' crown" support also carries towards its lower endEv a small transversely slidable locking pin 23 held forwardby a leaf spring 21.` This lower locking pin engages, at the appropriate' point inA the cycle, with a slot laf in the face of the staple driver l, and prevents any' downward motion of the crown support relative to the driver after the locking pin is engaged and until it is released as described hereinafter.

Soon after the outside former anel-I the leg support have reached their lowest position before the driving of the sta-ple (the lower locking pin 23 of the crown` supportingel'ement being then agoeuess dis-engaged), asl'oping face 15b: near the lowerl endv of the driver presses backv the said'V lower locking pin'A against its spring, until the slot 'I'a in. the face of the driver is in a. position in which.

it can engage with: the pin (Figure 10'). If there is anyv vertical downward motion ofv the crown support in opposition to its retaining spring l2 during this action', such motion must cease as soon as. the crown support meetsv the strongly spring-loaded leg support and downward driving connection between the crown support and thedrive'r isV therefore eiiected. In this relatively locked position', the driving: point of the driver is on the crown wI of. the staple, a slight clearance .being provided: to ensure this.

The subsequent stages. of the: driving stroke are' indicated in Figures 131, 12A and. 13'. The driver and crownsupportlocked together are'now moving vertically downwards against they leg sup-v port, the inclined face @b of the crown support forcing the leg support gradually out from the staple as previously described. Since, however",y the staple crown is fully supported on anormal tace relative to the direction of driving during this. movement and' at the same time thestruts formed' bythe undrivenportion of the staplel legs are supported laterally by the leg support while the length of these struts diminishes, the staple must retain its shape; This' support of the staple, shared by the two supporting elements, continues' until just before the stapley legs are' driven right through` the materiali Figure 113 shows the com`- pletion of driving.

Just before thisY stageY a slight turning move-- ment is giventothe eccentric Id engagingk the slot II in the crown support, This is effectedby the rocking of an arm' 33- (see Figures 2, 3 and 4-)f mounted on. the outer end of the pin iIl. A spring 313 engages one endof the arm' to urge the latter into its normal position with the eocen tricity of the pin Ii) vertical, and the opposite end of the arm 33 engages a slide member 35, slidably mountedv on' one side of the framework of the stitching head. A rocker to, pivoted' at 37 in the framework, carries at its-upper end, acam roller 38. A cam projection 39 on the cani plate 3o is so arranged that just before thev driver reaches the position of Figure 13, the roller 33 is engaged so as to-actuate1tlie rocker 36I and inove theY slide member 315 downwardly. The latter engages and movesV the arm 33 against the action of spring 34,. thereby turning theY pin i@ and unlockingA the crown support from the driver and allowing it tol disengage from the staple; as the crown support disengages, the leg support follows it, again moving into the staple under the action of the. spring 5a until the crown of the staple andthe driver forcev it out and the staple is completely driven, the driver meanwhile retaining the crown support on a shelf just below the incl-ined face lb.

After ashort dwellf to clinch. the stitch the outside former begins t'o rise carrying with it the leg support which is thus released from the control of the`l spring plunger E. The driver also returns; and the crown support now only imipolled'y upwards by its retaining spring l2', moves upwards resting against the shelf of the driver untilltl'i'e pins 8 reach the upper end of they slots El. Slight angular motion of the crown support t takes placedue tothe actionv of the pin lila, but the breadtl'i of the shelf on the driver is dimensioned to provide for this slight rotation of d, and this element reaches its uppermost-position under the influence of the driver motion and the spring I2l. Theldlriver and outside former continue their upward travel and the eccentric pin l0, which is returned to its normal position under the action of the spring 34 as soon as the cam projection 39 leaves the cam roller 38, can now restore the crown support to its Vertical position, and lastly its upper locking pin I3 is re-engaged when the outside former has completed its upward travel. The initial condition of the mechanism is now restored readsT for another cycle of operations.

It is possible, by dividing the staple supporting means into two portions separately mounted, and actuated as described above, to compel the staple to retain its shape by positive control at every stage of the driving operation.

The principle of the invention may also be applied to types of machines other than that above described, for example to machines where handling space is not required between the stitching head and the work support in which case one of the staple supporting elements e. g. the leg support need only have horizontal movement.

I claim:

l. Wire stitching mechanism comprising an outside staple former and a staple driver which reciprocate along a common axis, internal supports for the staple comprising two co-acting and relatively movable supporting elements, a face on one of said elements for supporting the crown of the staple, means for positioning and actuating said crown supporting element with the face thereof located beneath and in supporting relation with the crown of the staple from the be ginning and during the greater part of the driving operation, surfaces on the other of said elements for supporting the legs of the staple, and means for moving said other element transversely to the plane of the staple to support the undriven portion of the staple legs in conjunction with the outside former as the length oi said undriven portion diminishes.

2. Wire stitching mechanism comprising an outside staple former and a staple driver which reciprocate along a common axis, internal supports for the staple comprising two relatively movable elements, one of said elements having a face for supporting the crown of the staple and the other of said elements having a part for supporting the legs of the staple, co-acting inclined surfaces on Said elements, means for moving and positioning the crown supporting element with the face thereof located beneath the crown lof the staple and means for moving the leg supporting element to support the undriven portion of the staple legs in conjunction with the outside former, the inclined surface of the crown supporting element engaging the corresponding inclined surface of the leg supporting element to displace the latter element from the staple during the driving operation.

3. Wire stitching mechanism having an outside staple former and a staple driver which reciprocate along a common axis, and comprising in combination, a staple crown support and a staple leg support, means for positioning and guiding the crown support for movement in supporting relation with the crown of the staple, means for moving the leg support transversely of the plane of the staple to support the staple legs, and coacting faces on said supports for moving the leg support out of the staple as the staple is driven into the work.

4. Wire stitching mechanism having an outside staple former and a staple driver which reciprocate along a common axis, and comprising in combination, a staple crown support and a staple leg support, a part on said crown support for supporting a wire blank, means for positioning said crown support during the .bending of the wire over said part to form a staple, means for moving the crown support by the driver with said part positioned beneath the staple crown during the greater part of the driving operation, means for moving the leg support into supporting relation with the legs of the staple, and co-acting surfaces on said supports for progressively moving the leg support out of the staple during the driving of the staple into the work.

5. Wire stitching mechanism comprising an outside staple former and a staple driver which reciprocate along a common aXis, internal supports for the staple comprising a staple crown supporting element and a staple leg supporting element, co-acting inclined faces on said elements, a spring pressure device for urging the leg supporting element transversely of the plane of the staple to support the undriven portion of the staple legs in conjunction with the outside former, means for releasably connecting the crown supporting element to the staple driver, means for guiding the crown supporting element during its movement by and ahead of the driver with a face of said element positioned beneath the staple crown and retained substantially normal to the direction of drive from the beginning and during the greater part of the driving operation, the inclined surface of the crown supporting element engaging the corresponding surface of the leg supporting element and forcing the latter element progressively out of the staple against the spring pressure device as the undriven length of staple diminishes.

6. Wire stitching mechanism comprising an outside staple former and a staple driver which reciprocate along a common axis, internal supports for the staple comprising two relatively movable elements, one of said elements having a laterally extending face for supporting the crown of the staple and the other of said elements having a portion for supporting the legs of the staple, co-acting inclined surfaces on said elements, a spring-pressed device for urging the leg supporting element transversely of the plane of the staple to support the undriven portion of the staple legs in conjunction with the outside former, a lock device for automatically locking the crown supporting element to the staple driver at the beginning of the driving operation, means for positively guiding the crown supporting element for motion in the same line as the driver during the greater part of the driving operation with the face of said element positioned beneath the staple crown, and means for releasing the crown supporting element from the driver towards the end of the driving operation and displacing the crown supporting element transversely away from the crown allowing the leg supporting element to be moved by said spring-pressed device into the staple to sup-port the staple legs in conjunction with the outside former during the nal stages of the driving operation.

'7. Wire stitching mechanism comprising an outside staple former and a staple driver which reciprocate along a common axis, a staple leg support movable with the outside former, a staple crown support having a foot portion located beneath and supporting the crown of the staple, means for releasably connecting the crown' support to the driver on the completion of the forming operation, means for moving the leg sup'- port transversely of the plane of the staple to support the legs thereof as they are driven into the work, co-acting inclined surfaces on said supports which co-operate during the driving of the staple to displace the leg support from said staple, and means for releasing the crown support from the staple to permit the driver to complete the driving operation.

8. Wire stitching mechanism as claimed in claim 7, wherein the means for releasably connecting the crown support to the driver comprises a transversely movable spring latch mounted in said support and engageable during the driving stroke with a slot formed in the driver.

9. Wire stitching mechanism as claimed in claim 7, which comprises means for guiding'the crown support during the driving operations, said guiding means comprising pins carried by the stem of the crown support, said pins being slidable in slots formed in the stitching head to maintain the stem of the crown support substantially parallel to the driver, an eccentric pin journalled in the stitching head and engaging in a slot formed in the stem of said support, and means for rotating said eccentric pin when the crown support has completed its downward motion, the rotation of said pin moving said support transversely with respect to the staple and releasing the foot of the support from the staple crown.

10. Wire stitching mechanism as claimed in claim 7, which comprises a latch bolt provided in the stitching head for engaging and locking the crown support in position with the foot thereof located beneath a wire blank, said support acting as an inside former over which the wire is bent by the outside former to produce a staple, a lever mounted in the stitching head, and an arm on said lever cooperating with the outside former, to actuate the latch bolt.

11. Wire stitching mechanism comprising an outside staple former and a staple driver which reciprocate along a common axis, internal supports for the staple comprising an element for supporting the crown of the staple and an element carried by the outside former for supporting the legs of the staple, a spring-pressed device or urging the leg support between the staple legs to support said legs in conjunction with the outside former, a transversely movable spring latch in the crown support, a slot in the staple driver which is engaged by said spring latch to lock the crown support to the driver at a given point in the driver down stroke just before the driver strikes the staple crown, means for guiding the crown support during its downward movement by and ahead of the driver with a part of said support positioned beneath the staple crown and retained substantially normal to the direction of drive from the beginning and during the greater part of the driving operation, an inclined face on the crown support which co-acts with a corresponding face on the leg support to force the latter progressively out of the staple against the spring pressed device as the undriven length of the staple diminishes, and means for releasing the spring latch from the staple driver and causing the crown support to be returned to its initial position after completion of the driving operation.

12. Wire stitching mechanism comprising, in combination, an outside staple former and a staple driver which reciprocate along a common axis, internal supports for the staple comprising a staple leg support carried by the outside former and a staple crown support, a pin and slot connection between the crown support and the stitching head to guide the said support during its movement by and ahead of the driver, an eccentric pin journalled in the stitching head and en gaging in a slot formed in the crown support, means for moving the leg support transversely of the plane of the staple into supporting relation with the staple legs, an inclined surface on the foot of the crown support and a corresponding inclined surface on the leg support, said inclined surfaces co-acting during the driving stroke to force the leg support progressively out of the staple as the undriven length of the staple diminishes, and means for actuating said eccentric pin when the crown support has travelled its full distance downward to withdraw the foot of the crown support from the staple and release the latch device between the crown support and the staple driver.

13. Wire stitching mechanism comprising in combination an outside staple ,former and a staple driver which reciprocate along a common axis, a staple leg support carried by the outside former, a projecting face on said support, a spring plunger mounted in the stitching head and engageable with said face for moving the leg support into the staple during the down stroke of the former, a staple crown support having a foot portion positioned beneath a wire blank, means for locking the crown support against downward movement before and during the forming operation, the foot portion Serving as an inside forming element over which the staple is bent during the forming operation, a latch device carried by the crown support for connecting said support to the driver, means for releasing and allowing downward motion of the crown support at the completion of the forming stroke, co-acting inclined faces on the leg and crown supports, the inclined face on the crown support engaging the corresponding face on the leg support during the driving operation and forcing the leg support progressively out of the staple against the spring plunger as the undriven length of the staple diminishes, and means for releasing the crown support from the staple and driver and permitting the crown support to be returned to its initial position after completion of the driving operation.

14. Wire stitching mechanism as claimed in claim 13 wherein the means for locking the crown support against downward movement before and during the forming operation, comprises a latch bolt mounted in the stitching head, and a stepped face on the crown support engageable by the latch bolt to lock said support in position.

15. Wire stitching mechanism as claimed in claim 14, which comprises a lever pivotally mounted on the stitching head, a releasing pin carried by the driver for actuating said lever,

an arm on said lever engageable with the latch bolt, and spring means connected to said arm, said spring means holding the lever in a position into which the lever has been moved by the said releasing pin to maintain said latch bolt in released or locking relation with the crown support.

JOHN IRVING NASMITH.

No references cited.