US2944522A - Fastener driving apparatus - Google Patents

Description

R. H. DOYLE FASTENER DRIVING APPARATUS Filed Feb. 25. 1957 July 12, 1960 N INVENTOR RICHARD H. DOYLE QMWW RMQWJMQ m ATTORNEYS States application relates to a tastener driving apparatus and, more particularly, to a new and improved pneumatic- 2,944,522 2%?534.JQIQiJSEQ mounted within the cylinder. The cylinder is normally biased into engagement witha 'movably'mounted" valve seat carried on the housing" to close off communication between the chamber and the interior of the cylinderijlj When the tacker is to be operated, 'compressed air is exhausted from one side of the radially extending flange to displace the cylinder and thus admit 'a large volpnie of compressed air from the" chamber into'the cylinder, thereby 'to drive the piston downwardly at a'high ria't'e 'of speed so that the driving blade engages and drives a 'fas' tener, such as a staple or nail, which is supplied to a drive track through which the driving blade extends'jFIn ag cordance with" the features of the present invention, when thecylinder moves downwardly, an aperture formedin the lower extremity thereofmoves into alignment with an I aperture formed in'the wall of the housing defining the ally operated device for driving fasteners, such as staples and nails. In the copending application of Oscar A. Wandel and Richard H. Doyle, Serial No. 630,883, filed December 27, 1956, which application is assigned to the same assignee as thepresent application, there is disclosed a pneumaticallyoperated fastener driving device using a slidably mounted cylinder in which is disposed a piston for actuating a fastener driving blade or'element.

driving device, by providing'a lightweight piston *andiimf proved means including the movable} cylinder for in'stanchamber to provide an exhaust port to permit the air-'entrapped below thepiston to be exhausted to the atmos-f phereso that downward movement of thepiston is not therebyreftarde'd. F-urther; dfirin'g'ihis downward iri'ove ment of the driver 'blade, a lower extremity of the blade engages 'avalve operating elementso that a pistonre taneouslyfadmitting a lar'ge volume of, compressed air toy the cylinder, obtains deep'penet'ration of aworkpiecehy ajdlrivenfastener; However," this prior, driving device ton -l se -a compression spring interposed between the, and'a nosepieceffor the apparatus in order to -return the 'derf"whendhef cylinder moves to its uppermost position pistonto'it's' normal or released positionat'the'end er each poweror driving stroke, This springsomewhat 'omplicates he' designof the'housing for, the movable cylinderjand also restricts the size ofapistonbump'e'r which is used to cushion thepower stroke of the piston;

V N H g A A p w 7 H s W ment of theinain'valve seat opens an exhaust valve toyent Accordingly; one object'ofgthe present:inventionjis-to provide a new 'andimproved fastener driving apparatus;

Another object is to-provide such an apparafus using a pneumatic piston return.

Another'object is to provide a fastener driving device which obviates the need for a mechanical spring to return a work piston to a normal or released position.

A still further object is to provide a pneumatically ope'rated fastener driving device including 'a cylinder and ha ing novel means for selectively controlling the exhaus tion of a portion of said cylinder. 1 r r k V A further objectistoprovide new and improved-means controlled by movement ofa fastener driving element for supplying compressed air to return apiston.

turn "valveis opened and held open to admit compressed air to the lower-portionofthe'interionof the cylinderi However; this air is exhausted to atmosphere throughthe exhaust passageways in the cylinder described above,

" *Whe'n the apparatus is reIeaSedQcOrnpfessedaiI is again supplied gtofon'e' side of the piston defining fian'gednthe cylinderso'that this "'ylinder is movediupwardlyto close the, xhaust'p sageways for me'loweipdruoaer the cyliii in which it again engages the": main valve seat, passage ways formed on the inner 7 wall of the icylinder bypass a portionof the 7 compressed 'airentrapped in the upper por: tion of the cylinder to provide a P I Ssure difierential which causes downward movement of the valve seat andthe rcylind'er to a normalposition. This downward move:

thefiipper portion of; the cylinder. Concurrently were;

with," the oompressed air admitted by the piston return valve,"which isheld open by the displaced blade, builds up 'in the-lower portionof thecylin'der so that the piston is pneumatically returned to its normal position together withthe driving element. Returning the driver blade to its normal position closes the'piston return valve so'th'a't compressed air is no longersupplied to the lower portion a of the cylinder. If the piston and the driver bladein-l "Another ob ect 1s to provide a control valve having a valve operator'including a fastener driving-blade;

Another object is to providea' pistonand fastener driv ing blade assembly including means foroperatin'g a'valve.

Another object is to provide a'fastenerdriving assembly including a movable cylin'derfor providing valvemeans for controlling communication'between the atmosphere and the interior of the cylinder. V M a U A still further object is to provide fastener driving apparatus including pneumatic means controlled byafas' theYcontrol valve is located along the center linevof tener driving element for holding 'a work piston in a not mal'or released position.- a 1 r .7 t 'In accordance with these and many other objects, one embodiment of the invention comprises "a pneumatically operated tacker of the type-disclosed and described in detail in the aboveidentified copending' Wandel et 'al.

application. This device generally. comprises a housing definining a chamber in which is slidably mounted a cylinderhaving a radially extending flange defining a piston. IAiPiSton haViiIg-a connected driver blade .'is=-'slidably advertentlyfaremoved downwardly, the piston return valve isagainoperated bythe driverblade to adiniticonl pressed air to the 1 lower portion; of the" cylinder so as-td hold the piston in it's-"normal or uppermost position;

Injoneenibodiment ofthe present inventiomthe piston return valve includes an operating stem which is directly engaged by a flange for'rned on one side of the driver blade so as to open this valve aftera short initiai downwa'rd movement of the -'piston.*' *Inanother embodiment,

driving blade,' and" a valve operating element extend substantially parallel to the blade is provided with per-1 tions which extend outwardlylinto oflset openings formed in the drive track it: be enga ed by flanges of onset fdfg tio'ns formed at both edges offthe driver blade. L a T Many other objects and advantages of the present vention will become apparent from a consideration of gthe following description when taken in conjunction with the following drawings whereinzm- Fig. lis .a fragmentary sectional view ,rof'a pneu matically operated fastening device embodying the present invention which isshown in a normal or releasedv position;

Fig. 2is afragmentary sectional view, similar 10"Fi the fastener driving device in an operated position;

Fig. 3 is a fragmentary :sectional view taken along line 3- 3 in Fig. 2, assuming that the entire fastener driving device is illustrated therein, which shows one embodiment of a piston return valve and operator means therefor; g H s V '1 Fig. v is a fragmentary sectional view V illustrating anotherembodiinent ofthe piston return valve and operatolr rnealns therefor; and H v Fig, 5 is an enlarged fragn rentary sectional view of h pis c ir n a v a e a o i e 5- n assuming that the complete valve-structure is shown hs e n- ,1 l

Referring now to 'Fig. 1of the drawings, therein is disclosed'av pneumatic tacker or fastener driving device, indicated "generally as 10,'which is of the same type as that shown and described'in the above identified co pending Wandel et al. application. In general, the driving deviee, includes a housing '12 in which is defined a compressed air reservoir '14 and an enlarged chamber 16 inwhich is disposed a cylinder 18 having a pistondefining flange 118a slidably mounted in a cylindrical portion of the charnber 16. Afastener driving means includes a piston ;20 s'lidablymounted within the cylinder 18 and a driving blade 22 secured to the piston 20 which is adapted to move outwardly through a drivetrack 24 formed in'a nosepiece 12a of the housing 12 to engage and drive suitable fasteners, such as staples or nails, supplied to the drive track 24 bya magazine (not shown). The upper end of the cylinder is norm'ally, closed off from communication with the chamber 16, which is continuously supplied with compressed .air from the reservoir14, by a'main valve assembly 26 which is movably mpunte'd on ihe housing 12. a

To o r t t mak 0, a

control valve assembly28, whichpmay be of the typedisclosed in the oopending applicationof Oscar A. Wandel andRichard H.; Doyle, Serial No. 546,377., filed November l4, 1955, now abandoned, and assigned to the same assignee as the present application, is actuated to exhaust compressed air normally supplied to one side 'of the piston defining flange 18a, T his creates '8. pressure differential across the flange 18a sequentially to cause downward movement of the work cylinder 18 and upward movement of the main valve assembly 26 so that compressed air from the eham'ber :16 and the reservoir 14 flows into the interior of the cylinder 18, at substantially full line pressure, without;turbu lence, and in large quantities to drive the lightweightlpistonZi) downwardly at' a high rate of speed so thatthe blade 22 engages and drives a fastener. The upward movement of the main valve assembly closes an exhaust valve assembly I 30 to permit the T compressed air pressure to build up rapidly withinthe upper portion of the. cylinder 7. and the downward movement of the cylinder 18 vents the lower portion thereof tothe atmosphere to prevent any damping of'the downward movementof the piston 20.. i s

. .In accordance with the present invention, when the drive blade 22 moves. downwardly through the drive track24, a control or piston return valve 32 is operated held" open by the blade 22.to admit'coinpr'essed'air to the lower portion of the cylinder 18 beneath the piston However, this compressed air'doesnotretard' the downward movement of the' piston 20 inasmuch'as the lower portion *of the cylinder 18 is vented to 'the'atinosphere, as described above.

When the valve 28, which is manually or automatically operated, is released, the cylinder 18- moves upwardly to engage the main valve element 26, which-is disposed immediately adjacent the housing 10, to close off communication .between'the chamber 16*and' the interior of the cylinder 18. During this upward movementfthe exhaust c'onnection'for the lowerportionof the cylinder 18 is closed. Further, during this movement, the interior of theeylinder lB disposed above the piston 20 is placed in communication with the lower portion of the cylinderis by a plurality of restricted orifices so that the pressure of the compressed air in the upper portion of the cylinder 18 is decreased below that of the chamber 16. This pressure differential acts on the upper surface of the main valve assembly 26 to provide a-force which moves the engaged cylinder 18 and the main valveassembly 26 downwardly to the position illustrated in Fig. l.

In-movingdownwardly, thefmain valve assembly 26 opens the exhaust'valve assembly '30 so thatthepressure of the air trapped in the cylinder 18 between theupper surface of the piston 20 and the lower surface of the main valve assembly 26 is quicldy vented to atmosphere. In order to returnthe piston 20 to its normal position (Fig. 1) from the position illustrated in Fig. 2, the compressed air admitted into the lower portion of the interior of the cylinder 18 under thecontrol of the valve assembly 32 is permitted to build up during the upward movement of the. cylinder '18 inasmuch as the exhaust'connectionjfor this portion of the interior of'the cylinder 18 inow beenclosed by the upward movement of this cylinder. This compres'sed air acts on th'e'l'ower surface of the piston 20to move it upwardly to thejpo'siti'on illustrated in Fig 1,.I this upward movement serving to close the valve. 32 when the piston '20 'and"'t he'blade 22 afefreturned to their normalv position. If'the controlfvalvefifi is again operated, the'cornpressed air trapped inthe lower portion of the cylinder 18 is adequateto points: pistonj20 in its normal or releasediposition reoperation of the control valve f28. If, however, the tacker 10 reinains idle, the entrapped airin th'eilowr 'iid of-thecylinder '18 is'dissip'ated an'd'the ..piston Q2D jniay beginto' move downwardly so that theend of the driver blade '22 again operates the control valve ,32- to ,adn'iiti'air to the cylindereIS to'return the piston '20 to its normal or released position. L v s In view of the foreg'oing. general description and since the construction and operationof the pneumatic tacker 10"is set forth indetail in they above identified and latter filedi copending Wandel and Doyle application, 'a detailed descriptionyof the construction andoperatio'n of onlythe improvementsin theconstruction disclosed in this, prior application is' set forth herein. v

More specifically, in order to provide a control valve means for selectively exhausting the'lower portion-of the interior of the cylinder 18, a lower reduced diameter portion 18b thereof is provided witha pair of apertures 40. These apertures are normally disposed adjacent ,contiguous wallsurfaces .of thehousing 12 when the tack'er- 10 is in the released position illustrated in Fig.'l of the drawings, so as to close 01f communication between the atmosphere and thelower portion of the interior -ofthe cylinder 18. However, .when the control valvef2'8 is operated to cause downward movement ofthe cylinder 18, the openings it) move into alignment; with a pair of openings -42;formed' in the housing 12, thereby. to place theilower; portion 0f the; interior of the cylinder 1 in communicationjwith the'atmo'sphere. Since the cylinder 18= movesfdownwardly prior to downward movement of the'piston 20, the openings 40 and 42 exhaust the lower portion ofthe interior of -thecylinder-; 18 to prevent an entrapment of air therein which would retard downward movement of.,-thepiston 20. Alternatively, -whenthe control Valve;- 28 is released, to cause upward movement of the cylinder 18 to the position illustrated in Fig 1, the openings-40 and-42 are movedout ofi alignment so as to seal on; the lower; portion of the-interior of the cylinder 18. :Sealingthisportion of the; cylinder 18 at this time permits the'compressedair admitted under-thegcontrbl ofitheflvalve assembly 32 to return the piston 20 to its normalposition. I ..1 The controlivalveas'esmbly 32 is'selectively operated under thelcontrol of -the piston;=;20- and theydriving -h-lade 22 to selectively admit compressed air to the lower portion "of the interior-of the cylinder 18 both for returning? the piston 20 to itsznormal position and for retaining the? piston. in this normal or released position. The control valvev assembly 32 comprisesla valve ahead 44 which is disposed acounterbore 46 in the'nosepiece 12a;'of the housing 12 and which is connected to a valve operat-; ing stem '48r-slidably mountedon the nosepiece 12a. The counterbore 46 is closed by a threadedplugj 50 so that compressed air; which is continuously supplied to the: counterbore 46 from thereservoir. 14 through a passage wayt52,.'acts on the enlarged valve head 44 to seat it on a resilient O-ring 54 disposed inwthe counterbore 46, thereby: to prevent the flow of'compressed. air into the lower-portion of the'eylinder 18 when the tacker is'in the released. position illustrated in Fig. 1. When the valve. assembly 32-is displaced to the open position i llustratedin: Fig. 2, compressed air fiows' directly. from 'the' reservoir .14 through the passageway '52, the counterbore 46, a bore-- 56, and a-passageway 58 intothe cylinder 18. When the Y control valve 32 is released, the compressed air supplied by the: passageway 52 forcesithe head 44 of the'valveinto seating engagement with the resilient O-ring 54,- thereby to again'seal off communication between the counterbore 46andthe bore/56. I 'To providea means for selectively operating the com trol valve assembly'32, the driving blade 22 -is-pro'vid'ed: with a pair of upstanding or flanged edge portions 22a and 22b which are slidably received within offset-portions; 24d and 24b of thedrive track 24,'the drive track 24.extending through both the nose'piece' 12a and a resilient I bumper 60 disposed Within the lower portionofthe interior of the cylinder 18; The ends'of theflangededge; portions 22a and 22b are provided with tapered: or in clined' portions as indicated at 220 on the flanged edge's 22a. i This tapered portion 22cis disposed immediately adjacent a rounded end portion 48a of the valve stem .48 1 which'extends into the offset portion 24a of the drive track 24. p a w: When the piston and 'thedrive blade 22 move downwardly under thecontrol of the compressed air' admitted into the upper portion of the cylinder 18, the inclined portion 22c cams the valve stem 48 and the valve headv 44 to the right from the position illustrated in Fig. 1 to the position illustrated in'Fig. 2 so that'the control'valve 5; 32 is operated to admit air into the lower portion of the cylinder 18.-- The rounded end 48a of the valve stem 48 rides'over a flat upper surface of the flanged edge 22a to maintain the valve 32 in an open condition during theentire downward working stroke of the piston 20, during the entire upward return stroke of this piston, and until such time as the piston 20 is restored to its normal position as illustrated in Fig. lfof thedrawing s. 'In this manner; the'valve 32' is opened in response to the first downward movement of the piston 20 and is retained in its open position to continuously supply'compressed air to the lower portion of the cylinder 18 until such time as thef piston 20 is returned to its normal or released "position;

In operation, the control 'val've 28 is first actuatedj to cause downward movement of'the cylinder 18 and upward movementof the main valve assembly "26; as described in detail in the above identified and latter'filed 4 copending application, to simultaneously close'the exhaust? valve 30 and to admit compressed-air to the upper portion of-the cylinder 18. This downward movement "of the] cylinder 18 moves theopenings '40 and 42 into alignment so that, whenthe piston20 movesidownwardly, the air trapped beneath the piston'20 is exhausted to the atmosphere'through the aligned o'penings 40 and 42; Further, the initial downward movement of 'the piston20'and the driving blade 22 moves the cammed portion 220 ofthe flanged e'dge 2241' into engagement with th'c'e i'ounded end 48a of the 'valve' stem 48 so that the valve headi44j is displaced from the -O-ring 54 to admit compressed through the passageways 52, 46,56, and 58 'int'othelower portion of the cylinder 18. However, thiscompressed' airfiwhieh passes-through alplurality of somewhat re-'"r i tir'uiing' downward movement o-f'the piston '20 and the:

blade I22'holds the valve head 44 in the position illustrated in FigJ Z andalso causes a fastener to be engaged and driven by the blade22. I *When the control valve '28 is released, the cylinder: 18"'moves upwardly to engage the main valve assembly 26 immediately adjacent the upper end'of the chamber 16, as described in detail in the above'identified copend-:- ing application, so that the 'openings40 and 42 are moved; out of alignment to seal off communication between the; lower portion of the interior of the cylinder 18'andL the atmosphere. Accordingly, the compressed air-supplied from the-reservoir 14 under the control of'the valves as-i sembly 32 begins to accumulate in the lower portion of-= the' cylinder 18, but is not sufficient at this time to displace the piston'20tupwardly. Further, in moving upwardly; ailplurality of grooves 70,fo'rmed on the inner surface ofthe cylinder'18'are moved pasta sealing 0- ring72 carried on the piston 20 so that the compressed air entrapped in the upper portion'of the cylinder18v between the-upper. surface iofithe piston 20 and-the lower? surface of the'main valve assembly 26 'is partiallytex h'aused to the lower portion of the interior of the cylin-R (lei-718, thereby to'p rovide apressure differential across the main valve-assembly.'26-which causes the engaged main valve assembly 26 and the cylinderhlS to. move; downwardly to the position illustrated iniFigQI of the;

diaviiings. Itis possible-for the compressed air disposed-;

above the upper surface of the piston '20 to be exhausted 1; to =the'lowe'r portion of thecylinder 18 even though'come pressed air is being admittedt-to the lower portion of this cylinder inasmuch as the. pressure within; the lower portion, which is being vgradually increase'd -by the air. sup-r, plied by the control valve 32, is less;than the pressure of -th'e air entrapped between the main valveelernent 26f. and-theup'per surface of the. piston 20;] "When the engaged work .cylinder .18 I and main valve assembly 26 move downwardly to the position illustrated: in -Fig.- 1 of the drawings, the exhaust valve 30 is again; opened to exhaust the co'mpres sed air remaining ,within. the upper ."portion of thecylinderilS; T Returning the upper portion of the interiorof the cylinder -18 to' atmospheric pressure together with the progressive'builds; up of compressed air within thelower portion .of the; cylindert1 8 produces a difierential across, the piston 20. 1

so-that thecompressed air supplied by the 'control valve: assembly 32"quicklymoves'the piston 20 and thedriv-f;

upon the enlarged end'lsurface of the valve head 44'to; displace: it to the left and-into. sea-tingengagement with the'resilient 'O-ring 54; thereby closing off communicaa;

cylinder 18 andtthe compressed tion, between the reservoir 14.

The-compressed air trappedbeneath the piston 20 and the frictional engagement oftthe sealing Daring 722 with? th'e inner surface of-the cylinder'18 is suflici'ent to retain;

the piston 20 inits normal or released position. How-f:

ever, the compressed airtin the lower portion of, the

.cylindery18 soon becomes dissipated due to the lack of a sealingz. element betweenthe openings'42and the enduofin thereduced'diameter portion 18b ofthe cylinder 18 and, 71-: if -the frictional engagement of the O-ring 72 is not sufiia cient'to. retain the piston '20 .in. its normal position, the

gpiston 20? and the' bladew22 move slightly downwardly I so iii erally as 80, for controllingthe supply of compressedrain from the reservoir 14 to the lower extremity of the in terior of the cylinder 18. This valve construction com prises a housing 82"whicl1- is substantially. rectangular, in;

configuration and which .is mounted in a suitably formed opening in the nosepiece 12a ofthe hOllSlIlg312Of'2th tacker 10. The housing element or insert 82 i's,pr o-; vi-ded with a bore 84: and with a. counterbore 86.

withthe passageway 52'and the open end ofthe counter bore is closedby athreaded plug;90' having a resilient;

sealing O-ring- 92. The compressed airsuppliedthrougk the passageway 52 seats a valve head 941011 aresilient:

O-ring 96 to prevent the admission of compressed air to thelower portion of the cylinder 18. The valve head 94:.-

lsconnected to a valve operating element 97, whiclrisslidably mounted in the bore 84, by means of-a reduced; diameter. shank portion 98 The endof the-operating;

element or stem 97 is pneumatically biased 1111110, engage? ment with a pin 100'which ismovably mounted between,

bifurcated end portions 82a and 82b of the housing 616:.

ment 82 with the endsof the pin 100 disposed within-a5. pair of'sirnilarly formedand' opposite slots 102 andilMe provided in thenosepiece structure 12a. 11168101251025 and 104 are in communicationwith the. offset portions 24a and 24b of the drive track. 24.

In the normal position-of the control va1ve 80,z the compressed airlacting onthe valve head 94 displaces the;

operator element 97 to the left, so that'the pin 100 is disposed'beneath the inclinedportions. 22c of the-driver,

blade 22 and within the offset portions 24a and 24b .ofithe;

drive track 24. When the control valve 28v isoperated to initiatedownward movement of the piston 20, as,;dc-

scribed above, the inclined: portions 22c on the offset-v portions 22a and 22b of the driver blade 22' .engage'thea end portions of the pin 100 and displace this pin-to the" right within the slot defined by the bifurcated end por Adlit:v opening88 in the counter-bore 86 is in communication 1 tionsSZa and 82b so that the valve operating element 97 is displaced to the right to move the valve head'94;out-

of sealing engagement with the-O-ring 96. This permits.- the compressed air supplied by the passageway 52 to flowthrough the counterbore86, the bore 84, and an open mg 108 in the wall defining the bore 84 to be supplied to the passageway 48. In-this manner, downwardmove mentof the piston 20. and. the driver blade 22. operates;

the piston return control valve to supply compressadi air to the lower portion-of the interior of thecylinder-lfi: When the piston 201is returned to its normal or :re:

leased position under thecontrolof the valve 28,,as;

described above, the. driver blade. 22 is moved upwardly. so that the offset portions 22a and 22b of the. driver blade nolonger engage the ends of the pin and, according-- ly-,- the compressed air acting on the enlarged end of the;

valve head 94 displaces the. valve stem .97 to theright; so that the ends of the pin 100 again move into theoffset;

portions 24a and 24b of the drive track 24 and :so that the valve head 94-.again moves into sealing engagement; with the O-ring 9640 cut off communication-between theinterior of the cylinder 18 and the passageway 52,.

Accordingly, the piston return control valve assembly.- 80, byproviding the pin..100 which is. engaged by" both oftheoffset edges22aand 22b. of the driver blade. 22,2?

avoids any tendency to unequally stress. the driver. blade;

22.: during downward movement and thereby prevents anytendencyfor this blade to bind within the. drivetrackidue to unequaljloadingon. theedgesthereof. Eurthc'r,:.7' ,;mentof said piston for-supplying compressed medium to;

by: providing the operating-pin" 100, which is engaged by both edges of thedriver blade 22, thecontrol valvea80t can be centrallylocated relative to: the nosepiece 12a-of the tacker 10, as contrasted with the control valve 32 whichis displaced on the nosepiece 12a with respect as:

a center line or diameter passing therethrough.

. Insummary, the pneumatically operated fastener d-I'lYr': ing; device 10' of the present invention, although embody.+- ingthe generahconstruction and operational"technique;v

described andj'shown inthe above. identified. and'later filed copending Wandel and Doyle application, includes: new and improved means-for. returning the;piston;20.-to-

normal'or released position including control valve asv semblies 32 or 80 which are directly operated by the'driving-blade-Z2. These controlvalve assemblies, in obviat ing the need for a piston return spring, not only serve. to return the piston-20 and the driver. blade 22 to. their: normal position at the endof each fastener driving stroke: but also provide convenient pneumatic. means for retain-.' ing theseelements of the construction 10 in their --re-- leased position between successive operations of-the maker:

Although thepresent'invention has been describedin. conjunction with specific embodiments thereof, it-should:

be understood that numerous other modifications and embodiments may be provided by those skilled in the:

artwhich will fallv within the spirit and scope of the present invention.

What is claimed as new and desired to be secured by. Letters Patent of theUnited States is:

1; In a fastener driving device, structure defining; a1 drive=track lying within asingle plane and adaptedtoreceive fastenersto be driven, said structurealsmdefin,

ing an=opening offset relative-t0 said plane, a" fastenerdriving elementslidable in said drive trackaudinclude ing a.- member slidable in said offset opening, valve means and valve operator means projectinginto saidotfset opening and adapted to be engaged by said member.

2. The device, set forth in claim 1 in which saidmembe'r projects substantially perpendicularly outward from, said drlvingelement and includes aninclined end'poution- 3. In a fastener driving device,- structure defining.- a:

drive track-adapted to receive fastenersand including a pair of spaced offset portions, a fastener driving element. havingolfset members and slidable in said drive trackq.

Withsaid offset members in said offset portions, a valve,

and a valve operator having, portions disposed in said; offset-portions and adapted to be engaged by said offset, members for operating said valve.

. 4. In a fastenerdriving device, structure defining a.-

drive track having a pair of offset portions, a fastener driving blade slidable in said drive track and havingoffset elements slidable. in said offset portions, a valve: carried on -said structure, and means for operating said.

valve including an element disposed substantiallyv paral lel. to; said drive track and extending into said offset ,por

tions-to beactuated by said offset elements.

5.- Afastener driving device comprising a housing defining; a chamber, a cylinder movably mounted in. said,

chamber, a piston movably mounted in said cylinder, said cylinder includingmeans defining an exhaust passage way in communication with the interior ofsaid cylinder at a point disposed at one side ofsaid piston, andmeans for moving said cylinder relative to said housing to open and close said exhaust passageway.-

6. A fastener driving. apparatus comprising ahousing. defining a chamber, a cylinder movably mounted in said chamber, fastener driving meansincluding apistonslidafastener driving means, and means controlled by move said cylinder at the other side of said piston to restore said fastener driving means.

7. The fastener driving device set forth inclaim. 6 wherein said control means includes means for moving said cylinder back to said normal position to prevent the admission of said compressed medium to said one side of said piston and including means for exhausting the compressed medium from the cylinder on said'one side of the piston so' that the compressed medium on the other side of said piston is effective to restore said fastener driving means.

8. A fastener driving device using a compressed medium comprising a housing defining a chamber supplied with said compressed medium, a cylinder movably mounted in said chamber, a piston movably mounted in said cylinder, first valve means controlling communication between said chamber and the interior of said cylinder at one side of said piston, second valve means controlling communication between the interior of said cylinder at the other side of said piston and the atmosphere, and control means for selectively shifting the position of said cylinder relative to said housing to selectively open and close said first and second valve means whereby said piston is displaced relative to said cylinder by said compressed medium. 7 p

9. The fastener driving device set forth in claim 8 including a piston connected to said cylinder and in which said controlmeans includes means for selectively supplying said compressed medium to said piston.

10. A fastener driving apparatus using a compressed medium comprising a housing defining a chamber supplied with said compressed medium, a cylinder movably mounted in said chamber, fastener driving means including a piston slidably mounted in said cylinder, first control means for shifting said cylinder relative to said housing selectively to admit said compressed medium to and to exhaust said compressed medium from the interior of said cylinder for moving said piston, and second control means controlled by movement of said piston for admitting compressed medium to the interior of said cylinder.

:11. A fastener driving apparatus using a compressed medium comprising a housing defining a chamber supplied with said compressed medium, a cylinder movably mounted in said chamber, a piston movably mounted in said cylinder, said cylinder and said housing having openings forming valve means, first control means for shiftmg said cylinder between normal and displaced positions to admit compressed medium into said cylinder for movmg said piston, movement of said cylinder to said displaced position opening said valve means to provide an exhaust for the interior of said cylinder and movement of said cylinder to said normal position closing said valve -means, and second control means for supplying compressed medium to said cylinder.

12. The fastener driving apparatus set forth in claim 1 1 including a blade for driving fasteners operated by said piston and in which said second control means includes a valve actuated by said blade.

13. A fastener driving apparatus comprising a cylinder, a piston movably mounted in said cylinder, a fastener driving element operated by said piston, first valve means I for exhausting air from the portion of said cylinder disposed at one side of said piston, second valve means for admitting compressed air to said portion of said cylinder, means for moving said piston including means for opening and closing said first valve means, and control means for opening said second valve means as said first valve means is opened and for closing said second valve means after said first valve means is closed. 7'

14. The apparatus set forth in claim 13 in which said piston has a normal position from which it is moved by said moving means and in which said control means includes means actuated by said fastener driving element to open said second valve means when said piston is displaced from" an normal. position and to 'inaifitaifi 5id1 second valve means in an open condltionuntrl said prsto i" compressed air to said portion of the interior of said cylinder to move said piston to said normal position, and means for closing said first valve means during said movement of said piston to said normal position to retain the compressed air in said portion of the interior of said cylinder to hold said piston in said normal position.

16. The fastener driving device set forth in claim 15 in which the means for supplying compressed air to said portion of the interior of said sylinder includes second valve means operated by movement of said fastener driving means.

'17. A fastener driving apparatus comprising a housing defining a chamber for receiving compressed air, said chamber having a cylindrical recess, a cylinder element having a piston structure, said cylinder element being disposed in said chamber with said piston structure slidably mounted in said recess with one surface of said piston structure in communication with said compressed air, a valve seat carried on said housing, fastener driving means including a drive-piston slidably mounted in the interior of said cylinder element, first valve means for selectively controlling the application of compressed air to the'other surface of said piston structure so that said cylinder element is moved away from said valve seat to place one end of said cylinder element in communication with said reservoir and is moved into engagement with said valve seatto close 05 communication between said reservoir and said one end of said cylinder element, said cylinder defining an exhaust passageway which is opened by said movement of said cylinder element away from said valve seat to exhaust the other end of the cylinder element and which is closed by said movement of said cylinder element into engagement with said valve seat, and second valve means operated by said fastener driving means for admitting compressed air into said other end of said cylinder element.

18. A piston construction for a fastener driving apparatus comprising a piston, a unipl-anar fastener driving blade secured to said piston, and a projecting portion projecting perpendicularly outward from the plane of said blade and extending longitudinally along virtually the entire length thereof.

.19. A fastener driving apparatus comprising a structure including a cylinder, a piston slidably mounted in said cylinder for movement between a normal position and a displaced position, a fastener driving bladeactuated pressed air to said one portion of the cylinder, control means for admit-ting compressed air to a second portion of the interior of said cylinder to drive said piston from said normal position to said displaced position and for exhausting compressed air from said second portion of the cylinder to permit said piston to be returned to said normal position from said displaced position, said control means including means for opening said first valve means as said piston moves from said normal position to said displaced position and for closing said first valve means as said piston moves from said displaced position to said normal position, and means actuated by said fastener driving blade for holding said second valve means in an 171.. opjon condition whenever said piston is displaced "from- 2,472,352 said normal position. 2,729,198 I 2,774,968 References Cited in the file of this patent 12 333,4 2

UNITED STATES PATENTS 5 1,194,346 Akans Aug. 15, 1916 1,264,168 Elvin et a1. Apr. 30, 1918 Van Settert June 7, 1949" Faccou Jan. 3, 1956 Osborne et a1 Dec. 25, 1956 Sheerer May 6, 1958 FOREIGN PATENTS Great Britain Mar. 6, 1957

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