CA1044401A - Pneumatic apparatus - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A poppet valve member for use in pneumatic apparatus for driving fasteners or for other impacting applications. The valve member is useful for rapidly admitting high pressure air on command to the upper end of the drive cylinder of the apparatus. The valve member has a hollow circular body with different diameters at the ends, one end being closed off by an end wall. A coaxial extension formed on the end wall extends away from the body while a boss, formed on the other side of the end wall, extends coaxially within the body. A plate attached to the boss closes the other end of the body and has a smaller diameter than the outer diameter of the one end.
Finally, a passageway extends through the extension, the end wall, the boss and the plate for conducting air through the valve member.

Description

10~4401 -This application i8 a divlsion of Canadlan Patent Application Serial No. 244,381 filed January 28, 1976.
FIELD OF INVENTION
This invention pertains to pneumatic driving apparatu~
and more particularly to poppet valves for pneumatic fastener driving tools.
BACKGROUND_OF THE INVENTION
Pneumatic nail-driving tools are old in part and are exemplified by the devices disclosed in U.S. Patents 3,498,517, 3,060,441, 3,035,268, 3,060,440, 3,595,460 and 3,711,008. , Prior hand-held pneumatic driving devices known to the art have not been suitable fo~ heavy-duty fastener-driving : .
operations, e.g., operations requiring installation of nails ' ;~'-or fasteners to high strength substrates such as prestressed concrete having 5,000 ,to 10,000 psi compressive strength and ''', structural steel plates with a thickness of 3/16th inch or greater. As a consequence, most ''''- ' :' ' ~
-,; 2 ~, - - ~ ~. ~ , , . . . ' -~044401 heavy-duty fastener-driving operations are carricd out ~ith explosive-actuated devices which are time consuming and expensive ,'and dangerous to operate. Furthermor~, e~plosive-actuated `Ifastener-driving means have substantial recoil and noise problems.
S Prior attempts to provid2 pneuma.ic driving devices suitable ~,for heavy-duty fastener-driving operations have been generally unsuccessful due to the difficulty of generating the r~suired ,'~impact force to drive a nail or other fastener through high I strength substrates such as concrete and steel plate. Because of ,~the problems of generating the required acceleration, prior pneu-matic driving devices designed for heavy-duty fastener-driving ~operations have been unduly complicated and have required compii-¦~cated and large valving for feeding and e~ha~sting the pneumatic " fluid so as to generate the desired acceleration and im~act force.
~ Furthermore, most prior ~esigns have involved a mechanical spring for.assisting the driving member on its return stroke. Ho~ever, ! the inclusion of spring means has had the undesired effect of ! limiting the acceleration of the driving mem~er and the impact ! force exerted by such member on the fastener which is to be ¦ driven. Most hand-held prior art devices designed for pneumatical l~
,driving nails and similar fasteners have been low-energy devices, l¦i.e., devices that provide for little or no acceleration time ¦~between the commencement of the work or ariving stroke of the Ijdriving member and the impacting of the work by the fastener which iS driven by the driving member. As a consequence, prior pneumati~
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, -~ ~04~401 driving devices have had to be massive in order to generate sufficient energy to accomplish heavy-duty fastener driving operations. Unfortunately, such prior driving devices also tend to have severe recoil.
An ob~ective of the invention as described in the parent application is to provide a pneumatic driving apparatus for heavy-duty fastener-driving operations which is simpler and capable of developing substantially more driving power per unit volume than prior apparatus intended for similar tasks, and which at the same time is reliable, easy to maintain and relative-ly inexpensive to manufacture.
A further ob~ective of the inv`ention as described in the parent application is to provide a pneumatic driving apparatus -which is designed to permit precise control of the velocity of its driving piston, thereby controlling the energy output of the unit and making a maximum use of the available energy. -s ', ' , ,~ .", ',, :,'.. :.". ~ ,,,, ~ ., ~0~401 Still another obJect of the invention as described in the parent application i8 to provide a pneumatlc drlvlng apparatus which is designed so that the air power iB utilized to substantially its full line pressure, and which further ls characterized by a relatively small diameter, light-weight driving piston and unique valving for controlling flow of air..
SUMMARY OF THE INVENTION
The above-stated ob~ects are met with the invention as described in the parent application which provides apparatus for driving or lmpacting a fastener or other article comprising a cylinder, a hammer or impacting member, a fixed end means closing off one (the lower) end of the cylinder and defining an openlng in which the hammer ls slidably disposed, a piston connected to the hammer and reciprocally mounted within the cylinder for driving the hammer through a drive or impact stroke and a return stroke, an air reservoir, an air manifold or supply chamber connected to the air reservoir, a poppet valve for admitting high pressure air on command to the other (the upper) end of the cylinder from the air reservoir, the poppet valve including a movable poppet valve member adapted to engage and close off the upper end of the cylinder from the reservoir, a first control valve adapted (a) to transmit high pressure air to the poppet valve from the air manifold so as to cause the poppet valve to close off the upper end of the cylinder or (b) to e~haust high pressure air from the poppet valve ~o as to cause the poppet valve to open, and a second control Yalve . .
atapted to (a) transmit high pressure air from the air reservoir to the lower end of the cylinder 80 aa to cause the piston to ~ -retrsct the hammer when the poppet valve i8 closed, or th~ to ' ,:
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104~401 exhaust air f rom the lower end of the cylinder so that admittance of high pressure air to the upper end of the cylinder by opening the poppet valve will cause the piston to drive the hammer through its impact stroke, the second control valve being oper-able independently of the first control valve and the position of the piston within the cylinder.
The poppet valve mentioned in the parent invention is itself unique in its structure and operation and it aid considersbly in achieving the above-stated ob~ects with the invention of the parent application. Broadly speaking, therefore, the invention of the present application may be defined as a poppet valve member comprising: a hollow body of circular cross-section having a first outside diameter at one end and a second smaller outside diameter at the other end; àn integral end wall closing off the one end of the hollow body; an extension formed integral with one side of the wall, the extension being coaxial with and extending away from the hollow body; a boss formed integral with the opposite side of the wall, the boss being located within and extending coaxially of the hollow body;
a plate attached to the bosa and closing off the other end of the hollow body, the plate having a smaller diameter than the outside diameter of the one end of the hollow body; and a passageway extending through the extension, the wall, the boss and the plate for conducting air through the valve member.

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ILLUSTRATIVE EMBODIMENT OF THE INVENTION
In this application and the accompanying drawlngs, there i8 described and shown a preferred embodiment of the invention and certain modiflcatlons thereof, but lt is to be understood that these are merely exemplary and that other changes and modificatlons can be made within the scope of the invention.
THE DRAWINGS
Fig. 1 is a slde view in elevatlon of a nail driver constituting a preferred embodiment of the inventlon;
Fig. 2 18 an end vlew in elevation of the same devlce;
Flg. 3 is a sectional view taken along line 3-3 of Fig. 2 showlng the devlce with its hammer in a retracted or ready positlon;
Plgs. 3A and 3B are enlarged views of two portions of Fig. 3;
Flg. 4 is a view like that of Fig. 3 showing the same devlce wlth the hammer at the completion of lts impact stroke;
Plg. 5, appearlng on the same sheet as Flg. 3, is --a cross-sectlonal vlew of the nail magazine taken along llne 5-5 of Flg. 3;
Flg. 6 18 a vlew like Fig. 3 of another embodiment - ' of the lnventlon ln ready posltlon;
Fig. 7 shows the device of Fig. 5 with the hammer at the completion of its impact stroke; and Flgs. 8 and 9 are enlarged fragmentary sectional ~lows 1D elevation of an auxillary exhaust control valve that may be used ln the devlces of Figs. 3 and 6.

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lU~4401 .` ,f . DESCRIPTION OF T~IE INVENTIO~
Reierring now to Figs. 1 and 2, the illustrated apparatu~
comprises a hoilo~ housing 2; a cap member 4; a nail receiving and positioning he~d 6; and a magazine 8 for holding 2 supply oE
; :nails and fee~ing th~m to the nail receiving and posi~ioning hcad .
~,6. Cap member 4 and head 6 are detachably secured to the upper and lower ends of the housing by means of screws 10 and 11 which ~`are scre~ed into tapped holes formed in the housing. The maga-Izine is detachably secured to the head 6 by means of screws 12, .
j~which pass through holes in the heaa and are screwed into tappad , .
~holes in the adjacent end of the magazine. ' ,-Referring now to Pigs. 3 and 4, the upper end of the housing .
.has an end wall 1~ which serves as a poppet valve housing; To . .
,this end a cylindrical bore 15 is formed in the end wall 1~ and .
15 . J,the upper end of bore 15 is counterbored as showD at'16. Slidablyl mounted in bore 15 is a hollow poppet valve that is identified ¦ ,' ';generally by numeral 17 and which comprises a cylindrical wall 18 'sized to make a close sliding fit with bore 15, a peripherai flange 19 at the u~per end of wall 18 sized to make a close slid~
,iing fit in counterbore 16, and an upper end wall 20. The poppet ~: ~
jvalve also includes a centrally located boss 21 formed integral ""
with end wall 20 and spaced from wall 18 so as,to form an,inter- .
nal annular cavity 22. The outer surfaces of wall 18 and flange ~19 are provided with circumferentially-extending grooves in whic~ :- . -j,are disposed resilient sealing rings 23 that bear against.the -' ~,' ' ' , ' .'-, ' '. .
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. -.'' ',i ' . . ' ' ' ' '. .' i~surrounding surfaces that define bore 15 and co~ntcrbore 16 and llserve to prev~nt l~akage of fluid ~hile allowing tne poppet valve ¦
to move axially. Ring seals 23 are preferably but not necessar- ~
ily made of an elastoi~ier material and may be in the form of 0- ¦
rings. The upper cnd ~all 14 of housing 2 is preferably provided with one or more passageways 24 that lead ~ro~ counterbore 16 to the atmosphere. Passzgeways 24 serve as bleeds to pre~ent a pressure buildup in the space between the lower side o~ flange 19 ¦
' and the annular shoulder formed by the junction o~ bore 15 and ~¦counterbore 16.
¦~ The bottom end of the poppet valve is closed off by a sub- I
! stantially xigid circular metal plate 25 and a circulàr resilient ¦
sealing pad 26 bonded to plate 25. The latter elements are formed j with central apertures to accommodate a hollow screw or threaded j bushing 27 which is screwed into the lower end of an axial bore 28 ! formed in boss 21. Additionally, the poppet valve comprises a cyl indrical axial extension 29 which is formed integral with end ~all l~20 nd has an internal bore which forms an extension of~bore 28.
¦jThe cap member has a cavity 31 of circular cross-section to acco-- j modate extension 29 and the upper end of the latter has a peripher jal flange or piston 32 that is sized to make a close sliding fit i cavity 31. The outer surface of flange 32 has a circumferentially ')extending groove in which is position anather sealing ring 34 ~sim !ilar to ~ealing rings 23) that bears against the surrounding surf-liace of the cap member and serves to prevent leakage of fluia while t - `
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j. 1044401 j~allowing extension 29 to move axially in cavity 31. ~ resilient ~'sealing pad 35 is secured in the up2er end of ca~ity 31 for en-gagement by the flat upper end surface of extension 29. Pad 35 acts as a valve seat for extension 29. Additionally, cap member , 4 includes one or more passageways or ports 36 that ~tend from cavity 31 to the atmosphere. The hollo~ extension 29, bore 28, cavity 31, pad 35, and passage-~ays 36 together constitute a vent ',valve for selectively discharging fluid from the underside of the lipoppet valve to the atmosphere. Preferably the axial dim2nsions ¦iof cavity 31, extension 29, bore 15, counterbore 16, flange 19 and ¦¦wall 18 are set so that when the poppet valve is moved upwardly, !~ a small gap exists between surfaces 37 and 38 when the flat upper I,end surface of extension 29 is seated tightly against pad 35 as ~ sho~n in Fig. 4. The effective area of the annular upper surface j 37 of poppet`valve 17 is greater in area than the underside ~f paa I!26. . .
Ii Pad 26 functions to provide a tight sèal between the poppet i __ tivalYe and the upper edge of a cylinder 40 when the poppet valve !lis in its down or closed position ~Fig. 3). Cylinder 40 is jjformed with open top and bottom ends and its internal diametér ~¦is constant throughout its length. The bottom end of cylinder j40 is secured in an opening formed in the bottom end wall 42 of ~housing 2. Cylinder 40 may be secured to end wall 42 in various Iways, e.g., by a screw thread connection, a shrinX fit or by -jwelding or brazing. Preferably the bottom end of the cylinderhas two circumferential grooves to accommodate resilient sealing ¦rl*gs 43 ~liXe ring e - 1. 23 a*d 34~ ~h;-h bear tlghtly agai*st 0~
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~the surrounding surface of end wall 42. The bottom end of cylin-'der ~0 is closed off by a plug 44 ~rhich also may bc secured to the cylinder in various ways, e.g., by a scr~w thread connection, I
,'a sh~ink fit, or by welding or bra~ing. Leakage of fluid bet~een ¦
S :the outer surface of plug 44 and the inner surface of cylinder ¢0 ~is prevented by another resilient sealing ring 45 seated in a circumferential groove in the plug. The latter also is formed ,,t~ith a round axial bore 46 to slidably accommodate a hammer or iidriving member 47. The plug is formed ~Jith an internal groove jlaround bore 46 to accommodate a resilient sealing ring 48 'that ~surrounds and engages the outer surface of hammer 47 7ith just `
j~enough force to prevent leakage of fluid therebetveen while at the same time allowing the hammer to move axially. The upper ena 'of hammer 47 is attached to a circular piston 49 that has flat : 1-¦~upper and lower surfaces and is sized so that it makes a close ; -~'' sliding fit with the inner surface of cylind~r 40. Piston 49 has ,a peripheral groove in which is disposed a resilient sealing ring ¦ ~ -3jS0 that bears against the smooth inner surface of the cylinder ' ! "
~and functions to prevent fluid from leaking between the piston' 20 - 'and cylinder. An annular resilient cushion member 52 is attached !
~*o *he inner surface of plug 44. Preferably the inner diameter I -,of member 52 is sized so as to provide a substantial gap between ! t and hammer 47 in order to avoid any friction force that would i~t~nd to impede movement of the hammer. Cushion member 52 is .preferably made of an elastomer such as a synthetic or natural ¦rubber compound, but it also may be made of a resilient plastic ~material. '- ' ' ' 1! -:
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1~44401 ¦l The outer surface of cylinder 40 is spaced from the inner surface of housing 2 so as to provide a chamber 5~ which serves `as an air reservoir. Additionally, the outer diameter of cylin-I der 40 is less than the outer diameter of the poppet valve by a selected amount so that a substantial marginal portion of pad 26 projects radially of the cylinder as sho~m in Fig. 3. Preferably i '`but not necessarily, the upper end of the cylinder has 2n outside !
I`bevel 55 to ma~imize the amount of pad 26 whicH projects out be-31 yond the upper edge surface of cylinder 40.
¦ Still referring to Figs. 3 and 4, the housing 2 is formed with a hollow lateral extension 5~ which defines a manifold cham-~ber 58 for supplying air or other pressurized fluid to reservoir j,chamber 54 and also to other portions of the device as herein-! after described. Extension 57 has an inlet port 59 which is ¦Ithreaded for coupling to a flexible hose Iine tnot shown) leading ¦
i~to a regulated source of pressurized fluid, e.g., an air compres-sor. ~anifold chamber 58 communicates directly with reseryoir -¦ichamber 54 via a passageway 60. One portion of housing ëxtension i 57 is formed with a relatively thick wall section 62 which is ,~provided with a bore 63 to accommodate a control valve 64.
¦¦ Referring now to Figs. 3 and 3A, control valve 64 comprises a ~,control valve housing 65 which is secured in bore 63 by a dowel j!pin 61. As seen best in Fig. 3A, control valve housing 65 is ¦~olosed off at one end by a bushing 66 that defines a port o~ : - -I,orif~ice 67 1eading to passageway 60. An apertured pad 68, pref-¦!er~bly made of resilient materiaI, is secured to the inner end il ' ' ' : ' ' ' ' ' ........... .'."
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of bushing 66 and serves as a valve seat for a control valve mem- ¦
ber 69. Housing 65 also has a bore 70 at its other end to accom-modate a valve rod assembly 71 that is connected directly to valve member 69. At the inner end of bore 70, the valve housing ; 65 has a shouldc- to ~hich is secured another apertured pad i2 ~ .
.that is like pad 6% and also serves as a valve seat for valve i me~ber 69. .Intermediate the two valve seats, housing 65 is pro-vided with a side port that connects directly with one end of ! a passageway 73 formed in wall section 62. Connected to the ...
l~opposite end of passageway 73 is a tube 74 that.extends length~Jise lof chamber 5'.i and extends through and is secured in the upper .
end wall 14 of housing 2. The upper end of tube 74 communicates -,'directly with a passage~ay or cavity 75 in cap member 4 that ~ opens into co~nterbore 16 of the poppet valve housing. Referring .:
lS I again to the control valve, housing 65 hàs another port 76 that at one end communicates with bore 70 and at thë other ena is .open to the atmosohere via a slot 77 formed in the side of hous- : : :
.,ing 65. The valve rod assembly 71 includes a piston 79 that is . :
sized to make a slidin~ fit in bore 70. - . .
~' Control valve member 69 is shaped so that when it is movea up : . .
against pad 68, it ~ill close off port 67 and when it is moved . .
~idown against pad 72, it will close off the control valve chamber - : :
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i,from bore 70. }lot~ev~r, in either position control valve member ,l69 is incapable of blocking off the side port leading to passage-way 73. ~en the manifold inlet port 59 is connectea to a &ource ' of high pressure air, the air in man.ifold chamber 58 ill act via port 67 to force control valve m.c~r 69 do~m against pad 72, ~ whereby air ~ill flow through the control valve housing 65 up linto cavity 75 of c~p m~mb~r 74 via passageway 73 and tube 74, antl ¦Ithe resulting air pressure in cavity 75 will force poppet valve I~member 17 down onto the upper end of cylinder 40.
1~ The control valve member is shifted to its upper position by ¦!means of a trigger 82 that is pivotally connected to housing 2. -~IFor this purpose the bottom end wall 42 of housing 2 has a ver-jltically extending cavity 83 and a side opening 84 that inter-I, sects cavity 83. The inner end of trigger 82 extends through lS i!opening 84 into cavity 83 and has a tongue that extends into a ¦-,slot 86 in the side wall of housing 2 and is pivotally attached - ¦Ito the housing by a pivot pin 87. The outer end of trigger 82 l¦projects under the outer end of valve rod assembly 71~ When the ! trigger is pulled up, i.e., pivoted counterclockwise as viewad 20 ~ ! in Pig. 3, it will engage piston rod asse~ly 71 and foxce it jlupward so that valve member 69 will close off port 67 and allow 5 high pressure air in counterbore 16, cav~ity 75, tube 74 and ~ passageway 73 to be exhausted to the atmosphere via port 76 and I slot '? `
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The bottom ~nd ~1~11 42 of housing 2 also is formed ~Jith a circular bor~ to accommodate an e~haust or s~fe~y valve ~8 whicn is similar to control valve 64. As seen best in Fig. 3B, valve 8Pj!
i comprises an exhaus~ valve hou~ing 89 which is secured in the borc!
~ in end wall 42 in arly suitable manner, e.g. by a set scret~ 89A or , by a screw connection or a friction fit. Housing 89 is closed at j one end by a threaded bushing 90 that defines a port or orifice 1~91. An apertured pad 92, preferably made of a resilient material, ¦lis secured to the innQr end of bushing 90 and ser~es as a valve ,'seat for an exhaust valve member 93 which is attached to (a valve ! rod assembly 94 The other end of valve housing 89 has a bore 9S
to accommodate valve rod assembly 94. At the upper end o~ bore 95 ! the housing 89 has a shoulder to which is secùred another aper- ¦
j¦tured pad 96 which also serves as a seat for valve member 93;
,!The latter has a piston 97 that makes a sliding fit with bore 9S
,Valve housing 89 has a lower side port 9SA that connects bore 95 ¦ -~ with an exhaust port 98 formed in the lower end wall 42 of housing' - !j 2, and an upper side port 95B that connects its interior space lithrough a hole in the lower end of cylinder 40 with a passageway ~¦ 99 in the lower end wall 42. Passageway 99 communicates with the !! ~'nterior~of cylinder 40 through an opening in pad 52. Valve .
~jmember 93 is adapted to close off port 91 when it is moved upward i! against pad 92 and to close off the upper end of bore 95 when it 1 i8 ~eated against pad 96. However, in either position vaive j! . . .
member 93 i8 incapable of clo9ing off the upper side 958 that ,j ,',' . :'.. ' '`' '' ' -15- ' ' ,, :, . ' .,; ' , ,, ..

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!~ leads to passage~7ay 99. Hence, ~rhen valvo member 93 is seated .'against pad 96, air can flow from air reservoir 5~ into the lower ~,end of cylinder 40 v.ia port 91 and passa~eway 99, and e~haust, ¦.port 98 is closed off. When valve member 93 is seated against ' pad 92, port 91 is closed off and air can be exhausted from the j,lower end of cylinder 40 via passageway 99, bore 95 and exha-~st ~,,port 98. .' ~i Movement of valve member 93 is controlled by a mechanical jlinkaqe that is carried by the head 6. The upper end of head 16 has a cavity 102 and a boss 104 that extends up from its bot-' .
tom end wail l05 and preferably engages plug 44. Boss 104 has . an axial bore 106 that is aligned with and is sized to slidably .
accommodate ha~mer 47. ~ead 6 also has a lower axial extension :
, in the form of a foot 107 t~hich has a bore that is an extension of bore 106. The aforesaid mechanical linkage that controls . : -movement of valve member 93 comprises a lever arm 108 that is dis-posed in cavity 102 and an actuating rod 109 that is'slidably .' ~positioned in a bore 110 in foot 107 that extends paraliel to ~bore 106. One end of lever arm 108 is pivotally anchorea to ~~head 6 by means of a pivot pin 111. The other end of arm 108 is ~pivotally attached to the upper end of rod 109 by means of a pivotl -pin 113 that is carried by rod 109 and extends into an elongate.
........ ... ..jslot 114 in arm 108. The latter is pivotally connected,to valve . . member 93 by means of a pivot pin 115 that is attached to the . . . -: . 25 lower end of valve rod assembly 94 and extends into another : .:
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In the absence of any high pressure air in the device, the weight of rod 109 and arm 108 is suffici~nt to hold valve member , 93 down on pad 96 wh~n the device is oriented vertically as sho~,Jn ~ in Fig. 3. The l~n~th of rod 109 is such that it ~Jill project out!
beyond the flat bo~tom surface 118 of foot 107 a short distance, , e.g., 1/4-1/2 inch, wl~e'n valve meinber 93 is seated on paa 96 and ' will be flush with en~ surface 118 when valve member 93 is seated ¦
~'against pad 92. If,high pr~ssure air is supplied to the device, j,valve member 93 will remain seated against pad 96 regardless of ; -¦ithe orientation of the device until rod 109 is subjected to an ¦upward force sufficient to overcome the downward fiorce resulting - -'!from the influence of high pressure air in chamber 54 acting on jupper side of valve member 93. , :
, ! Referring again to Figs. 3-5, the magazine 8 i9 hollow and ,'defines'an elongate channel 122 defined by ,opposite side walls ! 124, a bottom wall 126, and a top wall 128. Each side wall is ~;formed with a relatively shallow upper groove 130 and a relatively 'deep lower groove 131 separated by a rib 132, Grooveg'130 act to , !:receive and guide the fasteners to be driven. ' ln this case the ' '20 fasteners comprise nails 134 whose shanks are embedded or fric- , -~'tionaily disposed in plastic sleeves 135 which are tied together ' I'by connecting sections 136. Sleeves 135 and sections 136 are - I,molded as a continuous strip. Sleeves 135 are sized to extend Iinto grQOVeS 130 so that they are slidably supported by ribs 132.
:'Also, sleeves 135 are made e~ual to or slightly greater in diame-ter than the heads of nails 134 and further their diameters,are ' ,.sizea qo that they will make a close fit with bore 106. Also, ~leeves,l35 have a length, preferably at least about 1/4n, suffi-~cient to keep the nail straight in bore 106 during the hammer'~
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104440~ l ! drive strokc. The front end of channel 122 communicat~s with an ; opening 138 in foot 107 which has a cross-secLional 5hape similar ,to that of channel 122 except that it lacks yrooves corresponding !
to grooves 131. I~nu~, at each of its opposite sides opening 138 : has a rib 139 corresponding to rib 132 so as to provide a sup~ort .
for sleeves 135. The series~of nails are urged forward to~.rard foo 107 by a pusher 140 which is disposed in channel 122 and has a ' rib 142 at each side which slidably fits into the adjacent groove i! 131 A tongue 196 on the lower side of pusher 140 is connected I,to one end of a tension spring 143 ~hich extends around a pulley 44 that is rotatably mounted on a shaft secured in one of the ~ide walls 124. The other end of spring 143 is secured to a pin 145 that also is anchored in a side wall 124. Spring 143 urges ,the pusher toward foot 107. Upper wall 128 of the magazine ter- 1 I,minates short of the rear end of the magazine so as to provide an l ^
~'end edge 147 that acts as a stop for a finger 148 on the upper end ~of pusher 140 whereby to prevent the front end of the pusher from ,entering bore 106 and interfering with hammer 47 when tXe last ,nail has been discharged. The magazine 8 also is formed with a foot 150 whose bo~tom end surface is flush with the bottom end ~surface of foot lQ7. The two feet 107 and 150 cooperate to stabi-,lize the fastening device and hold it perpendicular when it is placea against a substrate into which a nail 134 is to be driven.
jl The relativ~ sizes of orifices 67 and 91 (together with the j~mount by which the poppet valve pad 26 protrudes beyond the upper ed~e of cylinder 40) are controlled so as to prevent downward 'travel of hammer 47 and possibly accidental firing of the deYice 1~ ~ ,.
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as it is connected to the high pressure air supply ana also so as ¦
~ to assure rapid opening of the poppet valve, attain optimum utili-,~ zation of availab~e air power and limit the force rcquired to op-erate trigger valve 64. In this connection it is to be noted that ~,the volume of air reservoir 54 ~which also should be considered ! to include the volu~e of passayeway 60 and manifold chamber 58) is ~relatively large in comparison to both the internal volume of ,cylinder 40 and the combined volumes of the space above poppet ¦
~'valve member 17 when it is in its down position ~Fig. 3), i.e.
¦¦counterbore 16, chamber 75, tube 74 and passageway 73. Hence sub-¦¦stantially more air is required to be moved to effect a large !~ change in the air pressure in air reservoir 54 than is required ''`to be moved to effect a correspondiny change in the air pressure ,, , above the poppet valve or the air pres,sure below piston 49. To !~ avoid any possibility of hammer 47 being driven downward acciden-¦Itally as the high pressure air supply is connected to the device , ~whereby the nail located in bore 106 might be detached from the other nails and be driven down far enough to permit the next nail I'to be advanced into bore 106) it is essential to control the rela-I tive rates of flow of air (a) between manifold 58 and counterbore 16 and cavity 75, and also (b) between reservoir 54 and the under-~side of piston 49. This objective is achieved by appropriately 'proportioning the smallest effective cross-sectional area of the passageways connecting manifold chamber 58 with counterbore 16 ." ,~ -, , - ," , . ., ,' " ,' ,~
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104440~

'of the poppet valve casing, i.e. the cross-sectional area of orifice 67, and the smallest effective cross-sectional area of ;the passageway~ connecting manifold ch~mber 58 with reservoir 54 ~and the interior of cylinder 40 below piston 49, i.e. the cross- !
sectional area of orifice 91. The first mentioned cross-sectional !
area is made smaller than the second mentioned cross-sectional area. The relative sizes of the two aforesaid smallest effective i ~cross-sectional areas will depend upon the volumes o~ counterbore ¦
I,,16 and cavity 75, re~ervoir 54 and cylinder 40, the overlap of the ¦Ipoppet valve 17 with cylinder 40, the diameter of piston 49 and ¦jthe effective area of the upper surface 37 of poppet valve 17.
¦,~owever, in general best results are achieved when the second 'mentioned cross-sectional area i.e. orifice 91 is about ~our :
~times the first mentioned cross-sectional area, i.e. orifice ¦!67. Typically, the diameters of orifices 67 and 91 are !
about 1/8" and 1/4" respectively where piston 49 has a diametér !~ f about 3.0 inch and the overlap of poppet valve 17 is ! about 1/8~. The air supply iniet port 59 and passageway 60 - I are substantially greater than orifices 67 and 91 as shown in -I Fiqs. 3 and 4 (for convenience of illustration only, orifices ~67 and 91 are represented as approximately equal in the f,drawings). . - ;
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104440~ i .: l ' ,!
, Operation of the devic-e shown in Figs. 1-5 will now be des- I
,¦cribed. Air under pressure, e.g. 125 psi, is supplied to thc " manifold chamber 58 by connecting inlet port 59 to a suitable l'supply of pressurized air such as an air compressor (not sho~n) This air passes through the orifice 67 and acts on the valve 69 ,jso that the latter closes off the opening in pad 72. The air ,passing through orifice 67 proceeds through passage~lay 73 and tube i~i74 into the chamber 75 where it applies a force to the upper end I~f the poppet valve 17, whereby the lattèr is urged to assume the 'Iposition shown in Fi~. 3 wherein the rubber disc 26 forms a tight ¦!seal with the upper edge of cylinder 40. Simultaneously, air is supplied ~y passageway 60 to the air reservoir chamber 54 and pro-ceeds through the orifice 91 of exhaust valve 88 to urge valve mem- .
, Iber 93 dot~tn against pad 96 to prevent discharge of air from exit 15 . ¦.passageway 98. The air entering the chamber of exhaust valve 88 'jalso passes through passage-Yay 99 into the cylinder 40, thereby 'jproviding a force on the underside of piston 49 which holds the .plston up against the sealing disc 26 as shown in Fig. 3. Any air j,trapped between the upper end of the piston and the digc 26 is .
j~exhausted to the atmosphere via the passageway 28 and the ports ' '~36. The device is now in its normal equilibrium position and -:
~~cannot be fired unless the push rod 109. is forced upwaraly far j~enough for valve member 93 to unblock the opening in valve seat ' . .
96. If the trigger is squeezed while op9rating rod 109 i5 in ¦.the position shown in Pig. 3, the valve member 69 will ohange....... .
~ipositioDs and the air pressure acting on ,the upper Siae of the ~poppet valve 17 is released by discharge of.air.from cha~ber 75 ~:
~via tu~e 34,, the internal chamber of valve 64, and exit port 76.
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10444~1 Hence, due to the pressure in r~servoir 54, the poppet valve 17 will move up ar.d thereby allo~ prcssuriz~id air to ac~ on the ' upper end of piston 49. Hor"ever, no movement of the piston ~;ill occur because an equilibrium forc~ condition exists as a result of the opposi~g force of thc pressurized air acting on the botto~n surface of piston 49 and additional static frictional forces due to engagement of O-ring seal S0 with the cylinder ~0 and the ~ rod 47 with seal 48 (for this purpose, the seals 48 and S0 are ! arranged so that with commonly accepted mating tolerances they wil ¦,develop a total static frictional force which is at least substan-!~ tially equal to the downward force exerted on the piston resulting~
lfrom the area differentiàl betw~en its upper and lower surfaces:
i it is to be noted also that if the diameter of rod 47 were to be - made so large that the force resulting from the area differential ';is substantially greater than the static 'rictional forces exertedl-,-by the seals, all that will occur is that the piston 49 will merel~
crawl toward the lower end of the cylinder when the poppet valve is opened). If trigger 82 is repeatedly released and squeezed, the popp~t valve will repeatedly move toward and away , from cylinder 40 but piston 49 will remain stationary. In order j,to fire the unit, the safety mechanism actuator rod 109 must be ' pushed up far enou~h so that the valve member 93 now bloc~s ori-,~fice 91. When this occurs, the air pressure acting on the under~ -~,side of.piston 49 is rapidly exhausted to atmosphere by outflow.of ' air via passageway 99, valve ca~ing 8g, bore 95 and port 98 If thereafter the trigger 82 is squeezed so as to move the valve m~m-~er 69 up far enough to close off orifice 67, poppet valve 17 will rov~ up rapidly toward chamber 75 and the fuli line pressure in .
reservoir 54 will act on the upper end of piston 49 so as to cause -~

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S04~401 Li j the latter to movc rapidly through its normal firing stroke.
; The piston 49 will not return to its normal starting position until the actuator rod 109 is released and trigger ~2 is also ,;released.
' The advant~ges o~ controlling thc relative sizes of orifices 67 and 91 of the control and eYhaust valves will now be acscribed.
When inlet 59 is connected to a source oE high pr~ssure air, ~pressure builds up on both sides of poppet valve 17. If a rapid 'build-up of pressure were to occur in reservoir 5~, poppet valve l17 might open and piston 49 might be driven downwardly a substan-¦tial amount by the air pressure acting on its upper side. However ~making orifice 91 relatively large allo~s the air pressure inthe bottom end of cylinder 40 to build-up quite fast, whereby i piston 49 is placed almost immediately in an equilibrium condition;
j ~Jhere piston 49 is about 3.0 inches in diameter, the poppet ,valve stroke typically is about 3/8" and with a line pressure of I'about 125 psi, the poppet valve will open fully within about 3 I ¦imilliseconds. The speed at which the poppet valve will open is jinfluenced by the size of the vent opening in bushing 27 (as well !as by the amount of overlap of the poppet valve relative to cylin~
lider 40, and the smallest effective cross-sectional area of the `~
- I~passageways lèading from cavity 75 to the atmosphere via valve 64)~
¦jThe smaller the opening in bushing 27, the faster poppet valve 17 ¦'will open. ~owever, if the opening is too small, it wlll restric~t jthe rate of upward movement of piston 49; also a whistling noise jmar be produced when piston 49 undergoes its return stroke.

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104440~ I
i ~ypically where piston 49 is about 3.0" in diameter, the opening in bushing 27 is about 1/8 inch fo~ optimum oper~tion o~ the pop-pet valve.
It has abeen determined that certain desiqn criteria must be observed in order to promote optimum operation of the devlce.
In this connection it is to be appreciated that in order for the air power to be utilized to itC full line pressure, it is essen-tial that the poppet valve provide a relatively ~tide mouth for rapidly applying high pressure air from reservoir 54 to the up-I.'per end of cylinder 40. By way of example, with piston 49 having ¦~a diameter of about 3.00", the maximum poppet valve opening (i.e.
¦,the maximum gap between the poppet valve and cylinder 40) is I,preferably between 0.3 and 0.5 inch. Secondly, in order to allo~7 , the hammer to reach its maximum velocity under the applied pneu-I matic power, the length of the hammer 47 is set so that the hammer .
¦,experiences a predetermined amount of travel prior to driving the ~-' nail into the work-piece. This pretravel will vary accoraing to the nature o$ the work-piece or substrate into which the nail is ! to be driven, but preferably it is at least about two inches.
~ In its at-rest position, the hammer may be close to the nail posi- -tioned in bore 106, but preferably it is spaced from the nail a -I,substantial distance. - -¦. Figs. 6 and 7 disclose a modification of the invention incor-¦iporating a trigger lock mechanism. This modification is pre- ¦
25 . i~ferred for larger diameter hammers. In this connection it is to ,. . . ~. .
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~be recalled th~t whcrt the trigger of the embodiment of Figs. 3 and 4 is opera-ted without pushing safety rod 109 up far enough to block orifice 91, the poppet valve ~/ill open but no motion of ham-j ' mer 47 will occur b~cause an ~quilibrium force conaition exists because of rrictional forces on pis-on ring seal 50 and ha~er ` seal 48. ~lowev~r, if the hammer diameter and/or the line air pressure is increased, the force acting on the upper side of piston 49 may be so great relative to the force acting on the l,lower side of the piston as to cause the ha~mer to move toward the iinail in bore 106 when the trigger is sgueezed evèn though rod 109 ~! is not pushed up far enough to close off orifice 91 of the exhaust l¦valve. Hence, it may be desirable in certain cases to provide a ,'trigger safety mechanism to prevent movement of hammer 47 except j when safety rod 109 is depressed far enough to operate the '~exhaust valve. As a practical matter it has been found that the ,, `desired equilibrium force condition is easily attained ~here j~the ha~mer diameter is not larger than about 3/4" and does not ¦
_ ~,exceed about 20% of the diameter of piston 49, and the air pressure in reservoir 54 does not exce2d about 175 psig.
~ Referring now to Figs. 6 and 7, the head 6 is providea with a ~
I,second axially extending bore 160 in which is disposed a second ~ --;~operating rod 162. The upper end of rod 162 is pivotally connec- ¦
ted to one end of a link 163 which is pivotally attached to head ;6 by a pivot pin 164. The other end of link 163 is pivotally .
iiconnected to a crank 165 which is pivotally connected to head 6 .. 1. .......... -. . " . ,, ,. - " -, ", .' - . ' ~ . . ' ' ; , ' . ,.
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~04440~ 1 , ,; , by means of a pivot pin 166. The upper end of the crank extends into a notch formed at the inner end of trigger 82 and 2 side ; .
abutment 167 on the crank engages the inner surEace of the housing ,i2 to limit pivotal movement of the crank arm in a clockwise S direction. A compres~ion spring 169 acts bet~een a portion of ` the head 6 and the ~ottom end of cran~ arm 185 to urge the crank ~arm to the position shown in Fig. 6, whereby the botto~ end of , operating rod 162 protrudes slightly below the bottom surface '118 of footlO7. Crank 165, link 163, and rod 162 form a trigger io ¦~latch mechanism. So long as actuating rod 162 is not forced up-¦¦wardly in the foot 107, the spring 169 maintains the crank in the !!position shown in Pig. 6 whereby the upper end of the crank }ocks - !~ trigger 82 so that it cannot be squeezed to operate control valve j ~ 64. If, however, the device is held down on a substrate into !~ which a nail is to be driven so that the reaction force of the ¦ , - !~substrate forces actuating rod 162 upwardly and thereby causes i link 163 to pivot crank 165 counterclockwise ~Fig. 7) far enough - ~ifor its upper end to become disengaged from trigger 82, the trig , ger will be free to fire the device. Spring 169 will urge crank ¦,165 back to the position shown in Fig. 6 ~7hen the force urging ! ~- -!.rod 162 up~7ardly is removed. If trigger 82 is released after rod - ¦,162 has returned to the position shown in Pig. 6, crank arm 165 ~Will move clock~7ise under the influence of the notched end of ¦trlgger 82 far enough to allow the trigger to return to lts locked . 2S . ~position. AS is apparent, actuatlng rod l09 and 162 are located " ' ~ ' ' ` ' . '. . ' ~i , ,, ~
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~close enoug~ to each other so that ~hen foot 107 is passed do~n onto a substrate or worX-piece, both rods will be d~pressed a~
the same time. Preferably rod 109 projects out further from oot 107 than does rod 162, so as to assure that the latter ~ill not be, depressed without the former being depressed. More preferably, rod lO9 projects further than rod 162 such that trigger 82 re-~mains locked until rod lO9 has moved up enough to cause valve ¦!member 93 to block orifice 91.
¦ In practice the air pressure acting on valve mem~er 93 oE
~!exhaust valve 88 biases rod 109 downwara with a forca that is ~,sufficient to comply with statutory requirements. Typicaliy, safety laws for powder-actuated devices prescribe that a force !'f at least about 35 pounds be required to operate a safety 1~mechanism like rod lO9, and this requirement is easily satisfied by the pneumatic- force acting on valve member 93. However, if ~~ ~'~aesired, the force required to depres~ rod lO9 may be increased ~ ~
- jor decreased by merely changin~ the diameter of valve member 93, ~ -;lor by regulating the air pressure in reservoir 54, or by spring- ¦
i~biasing the rod. ~hus, as shown in Figs. 6 and 7, a tension ~
- 20 jspring 170 may be connected between link 108 and head 6 so as to` !
~,oppose upward movement of rod iog and valve assembly 71. -_,, - ~ . , Fig8. 8 and 9 illustrate operation of àn a ~ iliary exhaust ontrol valve that may be incorporated in the devices shown in I~Fig~. 3 and 6 for the purpose of further controlling the velocity .of piston 49 during the drive stroke so as to maxlmize the energy `. ;~ ' . ' ' ': ''. ' -~, - ' '' . , '-' . ', : - . ' , ' . .
-27~
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104440~

, output of hammer 47. As is obvious to a person skilled in the - '.art., the velocity achit~ved by the ha~er during its drive stro~e affects the energy output of the device. Because the device does not incorporate any spring for assisting piston 49 S to execute its r~turn st.roke, thc velocity at which hammer 47 is .driven do~n~ard when the device is fired depends upon the rapidity:
. with which the poppet valve fully opens to apply the full line ;~air pressure to the upper end of piston 49 and the rate at which ,the air pressure on the underside of the piston is relieved ~the )effect of friction on hammer 47 and piston 49 is almost negiigible . . .
!during the work stroXe). In the development of this invention, ¦,it has been determined that for certain cases if the passageway .-provided for exhausting air from the bottom end of cylinder 40 in . .
i.advance of piston 49 offered no impedence.to such air flow, the "energy output of hammer 47 would be diminished. This result is ¦Ibelieved to be due to a dissipation of air power because of move-.ment of the piston at the beginning of the work stroke ~Jhich pre- .
vents the hammer from achieving maximum acceleration. Ho~ever, . .
,passageway 99, valve 88 and exhaust port 98 do offer a measur~ble I.impedence to air flow and by appropriately controlling the size i,of the foregoing, the velocity of the hammer is controllable, with ...
¦Ithe result that a very high impact force is generated by the ham-~.mer on the nail in bore 106. By way of example, where piston 49 : ~
j-has a three inch diamster, the minimum opening provided by pas- .~ : -. .~25 - ~sageway 99, exhaust port.98 and th~e opening in valve~seat 96 is ~ :

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104440~ I

about 1/4 , (in practice passage~y 99, exhaust port 98 and the opening in valve seat 96 may but need not be made ~7ith equal diameters). Nevertheless it has been determined th~t if the minimum effective cross-sectional area of the exhaust path pro- !
vided for the bottom end of cylinder 40 is variable, the energy J
output of the unit may be further improved. Therefore, as sho-"n in Fiqs. 8 and 9 the exhaust port 98 is repl~ced by a tapered bore 172 which serves as a valve seat and a large counterbore 173.-¦
jlThe latter is threaded to receive a valve body 174 which only j~partly fills the same so as to leave a flow chamber 175. Valve ¦body 174 has one or more by-pass discharge passageways 176 and a l1main passageway 177 in ~Jhich is slidably mounted a valve member `lo178 having a tapered valve head 179 sized to seat in bore 172.
j1A compression spring 180 urges valve head 179 against seat 172. ¦ :
~'Valve member 178 has a through bore 182 ~hose diameter is relatively - i small compared to exhaust valve opening 95A, bore 172 and passage-~
~ ways 176. - `
il This auxiliary valve functions as follows. Daring the ~,initial part of the drive stroXe of hammer 47, air is exhaustea . through bore 182. Bore 182 is sized so that during the initial - ¦Ipart of the hammer's drive stroke air is exhausted at a first rate ! which allows the ha~mer to accelerate without any dissipation ~
-` - ! f air power. As the hammer co~tinues its work stroke, air jjpressure.builds up on the underside of piston 49 until finally .- 25 ~I-enough pneumatic force is exerted on thè flat end surface 184 ...... _.. ... _ . . . . . .......................... - ., . .; ., . -~ 29~ ` ; `

`-' ` I!` ` ` `- `~ ` . . .:. . -,, . . .. , , . . . -: .

10444~
.. !
' of valve head 179 to overcome the force of spring 180, whereupon valve member 178 rapidly moves a~/~y from valve seat 1~2 and thereby permits air to be e~hausted to the atmospher~ at a much E
, greatcr rate via passageways 176. In practice it is preferred that the auxiliary e~haus~ control valve be designed so as to open' ~hen ha~mer 47 has moved through about 40-80~ of its work s~ro~e .~
~ The invention he~ein described offers a number of advantages. ' ; For one thing, it provides a device ~hich is capable of develop- ¦
j-ing more power per unit volume than prior known devices of similar ;intent. By way of examole, devices made in accordance with this ~ invention and connected to an air supply of 125 psi are capable ~-- ',of driving nails with a length of 2" and a shank diameter of.
0.153" through 1" thick pine into 8000 psi pre-stressed concrete.
Secondly, it has safety features which prevent it from firing .accldentally. Thirdly, it cannot be fired in a so-called automati~
~or repeat mode; successive shots cannot be fired without first .
' releasing safety rod 109 and trigger 82 so that the unit can be .
` recharged. Fourth, the drive piston 49 is simple and can have a ~!smali weight and size due to the unit's operating efficiency, with' ..the result that the overall size of the device is substantially smaller than other known devices of similar power output. Fifthly- -~
- I the poppet valve s entirely pneumat~ca}ly operated and when ...
- ; open, provides a relatively large opening for applying air to . piston 49 from air reservoir 54. Also,.the poppet valve has a -- -~ low w d gbt-due to its hollow design~ Thig not only also reduces -~

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the overall weight of the device but also contributes to the pop- i pet valve's extrc~ely fast operating speed. Seventhly, optimum efficiency is achieved with rel~tiv~ly simple and reliable valv-ing. Still another advantage is that the device may be used to drive different typ~s ~f fasteners or for other impacting opera-tions, e.g., punching holes in a plate. Furthermore, the device may be designed to accept a pre-filled disposable magazine in 'place of the refilla~le magazine 8. Also, the device is rela-tively quiet when o~erated. Still another advantagè resides o !~ from the fact that the upper'end of the device may be provided l! with a knob or handle as shown for pressing it down onto a sub-~,strate with enough force to depress rod 109 tand also rod 162).
I~ A further significant advantage with respect to extending' ¦ithe life of the tool is derived from the fact that the hammer 47 j is made long enough so that its outer end will protrude from the : end surface 118 of foot 107 as the piston 49 reaches cushion 52 -at the end of its work stroke.(see Figs. 4 and 7). Preferably, ~he hammer is made long enough so that it ~7iil project at least ' about V 16th inch and more ~preferably 3~16th inch) beyond tha end~
- 20 surface 118 of the foot 107 before the piston 49 commences to : --compress the cushion 52. In driving a nail into a rigid sub-trate, e.g.~ a metal plate overlying à concrete floor, the end ;surfac~ 118 engages the work, and the nail driving stroke is ... _ _ ; : -- - - -31- ' ' _ ~.~. .. , ., .... .. .. .. , . .... . . ,,, . , ''' ' ~ ' ' ' ,' ' '' ''' ' ' ' ' ' ,:

- .. . .. . , . .......................... . .: , ,' 104440~ : ~

completed when th~ end of the ha~ner is flush with the end sur-'face 118. ~lowever, th~ pneumatic iorce driving the hammer will ¦urge it to keep moving down and, since it is lon~ enouqh to do so, the hammer will mo~e bcyond the end surEace 118 before tks , cushion 52 b~gins to ~xert a deccllerating force on piston 49.
This movement of the hammer b~yond surface 118 causes the tool to recoil up away from the work. This upward recoil of the tool llallows the valve member 93 o~ exhaust valve 88 to move atYay from jlits valve seat 92 (due to the differential between the relatively I~high pressure in chamber 54 and the near atmospheric pressure in ¦Ivalve body 89) just enough to let high pressure air pass from chamber 54 through the interior of valve body 89 into cylinder -40 on the underside of piston 49. In this connection it is to i,be noted that since valve member 93 makes a sliding fit with the - lS livalve body 89 (typically a diametral clearance of batween ~.001 an ~-!' 0.005 inch is provided), air from chamber 54 can Ieak past the _~ !tvalve member 93-as soon as it is moved off of its valve seat 92, Iior its valve seat 96 ~the valve member 69 of control valve 64 -lima~es a comparable sliding fit in its valve body 65~. As a -!jconsequence of the exhaust valve 88 opening enough to allow air ¦Ito pass from chamber 54 into the bottom end of cylinder 40, a pneumatic ~orce or air cushion is provided on the underside of the piston which tends to decellerate the piston rapidly so that the piston compresses the cushion 52 only slightly or stops ~~~5 ll~ust short of it. As a consequence, the piston does not - !~strike the cushion 52 hard enough to put a ;jlarge tens~le stress on the bolts 11 which hold ¦! : . . .:

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1~)44*~
Il I
~Ithe nail receivin~ or positioning ~ead 6 to the housing 2.
ithout this decellerating action at the terminal portion of the driving stroke of the ham~er, the force exerted by the piston ¦ on the end wall memher ~4, and ~hus on the head 6, might ovcrload !
!the screws 11 and thus might tend to damage the tool or cause its ¦
~hreakdown after a short period of use. The decelleration of the hammer is very fast and occurs almost instantaneously after the. .
bottom end of the hammer has moved flush with the end surface 118 . of foot.107. This same feature prevents damage to the tool in the event it is held against a work surface and fired after .
. ¦the supply of nails has been exhausted. In such event, the .
... ..... ..Ihammer will strike the work surface hefore the piston reaches cushion 52 ana the recoil of the tool ~ill cause valve 88 to ,open enough to decellerate the piston and therehY prevent the .
ipiston from aestructively impacting.the cushion as previously .
jdescribed. ~t is to be notea that the slight opening of exhaust ¦ivalve 88 ~hich occurs on the upward recoil movement of the tool ¦does not cause the piston 49 to move upward again, for the simple . ¦ reason that the poppet valve 17 will still be open. - Piston 49 20 can move up again only after the operator has releasea trigger 82.
. ~ A final advantage is that the device is capable of a number lof modiications obvious to persons skilled in the art without ~.. ¦detractinq from the advantages already noted. - -~ : .
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Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A poppet valve member comprising:
a hollow body of circular cross-section having a first out-side diameter at one end and a second smaller outside diameter at the other end;
an integral end wall closing off said one end of said hollow body;
an extension formed integral with one side of said wall, said extension being coaxial with and extending away from said hollow body;
a boss formed integral with the opposite side of said wall, said boss being located within and extending coaxially of said hollow body;
a plate attached to said boss and closing off the other end of said hollow body, said plate having a smaller diameter than the outside diameter of said one end of said hollow body; and a passageway extending through said extension, said wall, said boss and said plate for conducting air through said valve member.

2. A poppet valve member according to claim 1 wherein said plate has a resilient surface facing away from said end wall.

3. A poppet valve member according to claim 1 or 2 wherein said plate is attached to said boss by means of a fastener which extends through said plate and is affixed to said boss, and further wherein a part of said passageway consists of a hole extending lengthwise through said fastener.

4. A poppet valve member according to claim 1 or 2 wherein said plate has a center hole, and further including a fastener extending through said center hole and affixed to said boss, said fastener serving to lock said plate to said boss.

5. A poppet valve member according to claim 1 or 2 wherein said boss has a threaded opening, and further including a screw engaged in said threaded opening and locking said plate to said boss.

6. A poppet valve member according to claim 1 or 2 wherein said plate is a laminate consisting of a metal plate and a resilient cover facing from said end wall.

7. A poppet valve member according to claim 1 or 2 wherein the diameter of said plate is substantially identical to said second outside diameter of said hollow body.