US3494125A

US3494125A - Powder actuated tool

Info

Publication number: US3494125A
Application number: US739392A
Authority: US
Inventors: Dale L Robinson
Original assignee: Omark Industries Inc
Current assignee: Omark Industries Inc; Thomas and Betts Holdings Inc
Priority date: 1968-06-24
Filing date: 1968-06-24
Publication date: 1970-02-10
Anticipated expiration: 1987-02-10
Also published as: DE6925088U; DE1932003C3; DE1932003B2; DE1932003A1; GB1252030A

Description

Feb. 10, 1970 0. L. ROB INSON POWDER ACTUATED TOOL 2 Sheets-She t 1 Filed June 24, 1968 DALE L. ROBINSON INVENTOR BUG/(HORN, BLORE, KLAROU/ST 8 SPAR/(MAN ATTORNEYS Feb. '10, 1970 o. L. ROBINSON 3,4 POWDER ACTUATED TOOL Filed June 24, 1968 2 Sheets-Sheet 2 FIG. 4

DALE L ROBINSON INVENTOR BUC/(HOR/V, BLORE, KLAROU/ST 8 SPAR/(MAN 47' 7' OR/VE KS United States Patent 3,494,125 POWDER ACTUATED TOOL Dale L. Robinson, Portland, 0reg., assignor to Omar-k Industries, Inc., Portland, Oreg., a corporation of Oregon Filed June 24, 1968, Ser. No. 739,392 Int. Cl. F011) 29/08; B25c 1/12, N14

US. Cl. 6026.1 13 Claims ABSTRACT OF THE DISCLOSURE A captive piston type of powder actuated tool is provided with a barrel pivotally engaged by the forward end of the tool housing so that the breech end of the barrel can be upraised into a loading position. An elongated handle-operated sleeve is slidably carried on the barrel and substantially covers the barrel. This sleeve includes a piston retractor portion provided with means extending through a slot in the barrel for engaging the head of the piston, and by means of which the piston is returned to an operative position after firing. The piston-return operation is accomplished by pulling the sleeve rearwardly partially otf the barrel. The barrel can be pivotally returned to its normal position, in alignment with the tools breech-block, only after the sleeve has been moved forwardly out of the way of the breech-block. Such forward return of the sleeve clears the piston retractor mechanism from the firing path of the piston.

BACKGROUND OF THE INVENTION Piston type explosive actuated tools, e.g. for driving fastener devices into concrete or masonry walls, conventionally employ a blank cartridge for providing the explosive gases applied to drive the fastener device. Such a tool is cocked by pressure of the muzzle against a workpiece or wall, resulting in movement of the tools breechblock into a firing position. The cartridge may then be fired to force the captive piston through the barrel for driving the fastener device. After firing, the barrel and the breech-block are separated so that a new cartridge or power load may be inserted, and the captive piston must be returned to its firing position. Various constructions have been employed heretofore to facilitate the loading and piston return operations. The barrel may be rotated laterally to the side of the tool facilitating removal of the captive piston to a firing position and insertion of a new load. Alternatively, the barrel may be movable longitudinally forward of the tool for retraction of the piston and reloading. In the case of these constructions and other similar ararngements, the tool mechanism is apt to be quite complex and/ or somewhat unbalanced.

In the copending application 737,900 of Raymond V. Pomeroy, filed June 18, 1968, assigned to the assignee of the present invention, there is disclosed and claimed a powder actuated tool of the captive piston type wherein the breech end of the barrel may be pivoted away from the tools breech-block into a loading position. The tool of the Pomeroy application further includes a piston retractor slidably carried by the barrel for moving the captive piston into a firing position. The tool is of compact and balanced construction, and is easy to handle and to operate, as well as being economical to manufacture. In the Pomeroy tool, however, the tools barrel is for the most part exposed, and it has been found that a tool of this type can be cocked against a workpiece or wall and then retained in a cocked position by grasping the barrel, when the tool may no longer be in engagement with a wall or workpiece. As a result, it is sometimes possible to fire the tool improperly or in an unsafe manner.

Furthermore, location of the piston retracting handles "ice in the tool of the aforementioned application, close to the muzzle end of the tool, requires the tools operator to reach farther in retracting a piston than in performing other tool operations.

SUMMARY OF THE INVENTION According to the present invention a powder actuated tool comprises a housing including a rearward breech portion and a forward barrel portion. The tools barrel is cradled by the barrel portion when the barrel is in a first position in substantial alignment with the tools breech-block. The barrel is pivotally engaged by the barrel portion at a forward location so that the breech end of the barrel can be pivotally upraised away from the breech-block into a loading position. The tool further comprises a sleeve slidably enclosing the barrel, the sleeve including a retractor means for engaging the piston, and a rearward handle which is manually engageable for moving the piston retractor means. The piston may be moved thereby to a firing position toward the breech end of the barrel. When the sleeve is moved for positioning the piston in its firing position, the sleeve extends beyond the tools breech-block, preventing closure and firing of the tool until the sleeve is once again moved forwardly for placing the retractor means out of the way of the pistons travel during firing. The sleeve substantially covers the barrel and prevents retention of the tool in a cocked position when the same is not urged against a workpiece. Also, rearward placement of the handle at the breech end of the sleeve adjacent the tools breech-block enhances the ease of operation of the tool.

It is accordingly an object of the present invention to provide an improved powder actuated tool of the captive piston type which is Well balanced, compact, and easily manufactured.

It is a further object of the present invention to provide an improved powder actuated tool of the captive piston type which is safer and more convenient in operation.

The subject matter which I regard as my invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. The invention, however, both as to organization and method of operation together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings wherein like reference characters refer to like elements.

DRAWINGS FIG. 1 is a longitudinal cross section of a powder actuated tool according to the present invention;

FIG. 2 is a lateral cross section of the FIG. 1 tool taken at 2-2 in FIG. 1;

FIG. 3 is a lateral cross section of the FIG. 1 tool taken at 33 in FIG. 1;

FIG. 4 is a top view partially broken away in horizontal cross section of the FIG. 1 tool; and

FIG. 5 is a side view of the FIG. 1 tool in a loading position thereof.

DETAILED DESCRIPTION Referring to the drawings, an explosively operated tool includes a housing generally indicated at 10 including a forward portion 12 which may be designated as a barrel portion and a rearward portion 13 which may be designated as a breech portion. Rearward portion 13 includes a handle portion or grip 118. Barrel portion 12 is semicircular in cross section and cradles barrel 14 received within sleeve 17 when the barrel is in a first position. In this first position, the barrel is aligned with the breechblock 16, the latter being located in the breech portion of the housing. Sleeve 17 is metal and extends over the barrel substantially along the barrel portion of the housing when the barrel is aligned with the breechblock.

Barrel 14 is cylindrical and extends from muzzle 15 rearwardly to a power plug 18 received in the breech end of the barrel. The barrel is provided with an inner bore 20 within which a captive piston 22 is slidable, such piston having an enlarged piston head 24 which slides along inner bore 20, and a ram or plunger 26 adapted to contact and drive the head of a fastener device (not shown) into a workpiece at the left end of muzzle 15. Enlarged head 24 of the captive piston includes a rearward head portion and a forward head portion 27 slidably engaged with the inside of the barrel bore. Head portion 25 is suitably provided with a piston ring or seal 32 therearound to prevent excessive escape of gas past head 24. Power plug 18 is threadably received in the breech end of the barrel, power plug 18 including a chamber 36 for receiving a power load or cartridge.

Breechblock 16 is longitudinally slidable within breech portion 13 of the housing and is recessed at 38 to receive power plug 18 in the firing position thereof. Breechblock 16 slidably carries firing pin holder 40, in turn carrying a tapered firing pin 42. The firing pin holder is normally held in a retracted position relative to breechblock 16 by sear 44 which is urged at this time by spring 46 to a location adjacent an edge 48 of the breechblock. When the tool is cocked and the breechblock is forced to the right into a cocked position against the spring bias of springs 50 and 52, sear 44 will be aligned with trigger bar 54 and can be moved upwardly by trigger bar 54. When breechblock 16 is in such cocked position, firing pin spring 56 is compressed, and upward movement of the sear 44 causes tapered firing pin 42 to be driven by spring 56 into tapered bore 58 in the breechblock 16. The firing pin 42 is adapted to project through tapered bore 58 and strike a rim fire power load or the like positioned in chamber 36. To fire the tool, trigger 60 is compressed against spring 62 moving trigger bar 54 upward into contact with sear 44, providing the latter is in cocked position. Trigger bar 54 is carried in a vertical slot in the trigger and is pivoted at 57, being maintained in alignment with the trigger by internal springs 59. This mechanism permits the trigger bar 54 to turn in a clockwise manner without damage in the event that the tool is cocked with the trigger compressed. In this event, trigger bar 54 will merely rotate in a clockwise sense as the side of sear 44 contacts the same. The tool may then not be fired until the trigger is released and compressed again.

. The barrel portion 12-of the housing, being semicircular in cross section, is substantially channel-shaped and open upwardly where it receives or cradles cylindrical barrel 14, as enclosed in sleeve 17, when the barrel is in a first position in alignment with breechblock 16. The barrel 14 is pivotally engaged by the barrel portion 12 of the housing at a location toward the muzzle end of the barrel so that the breech end of the barrel can be upraised away from the breechblock into loading position. Pin member is carried by the barrel substantially at the aforementioned location toward the muzzle end of the barrel, pin member 120 extending vertically from the lower side of the barrel Where it is received in a longitudinal slot 122 in barrel portion 12 of the housing. Pin member 120 can move between the left hand end wall of slot 122, as viewed in FIG. 1, and horizontal roll pin 124 carried in the barrel portion 12 of the housing, pin 124 in effect defining the right end of slot 122. Pin member 120 thereby permits longitudinal sliding movement of the barrel for full engagement of power plug 18 within recess 38 of breechblock 16, as well as movement of the breechblock 16 within breech portion 13 of the housing into the aforementioned cocked position. As viewed in FIG. 1, the barrel may thus be moved to the left so that power plug 18 no longer engages breechblock 16, or the barrel may be moved to the right into a fully cocked position, compressing breechblock 16 against the bias of springs 50 and 52 until sear 44 is over trigger bar 54. In the cocked position of the tool, barrel 14, as well as sleeve 17, extend within breech portion 13 of the housing. For disassembly of the tool, roll pin 124 may be removed permitting the upraised barrel (as illustrated, for example, in FIG. 5') to be Withdrawn upwards and to the right, since horizontal pin 124 no longer blocks passage of vertical pin member 120.

The barrel portion 12 is provided with an arched barrel retaining member 68 proximate and above the location of pin member 120. The arched barrel retaining member 68 has an inner surface 70 semicircular in cross section which substantially matches the cylindrical barrel 14, but which is angled upwardly and to the right in FIG. 1. It will be apparent that barrel 14 may be moved to the left whereby power plug 18 clears breechblock 16, and then the breech end of the barrel may be moved upwardly into a loading position (as seen in FIG. 5), with the barrel pivoting at its forward end. At this time, arched barrel retaining member 68 limits the upward movement of the barrel, and when barrel 14 is upraised as far as it will go, the inner surface 70 of the retaining member substantially matches or cradles the upper side of barrel 14 and sleeve 17.

The barrel 14 is provided with a longitudinal slot 72 on the underside thereof or the side toward barrel portion 12 of the housing. This longitudinal slot does not extend the full length of the barrel, butstops short of the breech and muzzle ends thereof as illustrated. Thus, ring 32 on piston head 24 is located a predetermined distance toward power plug 18 from the breech end of slot 72 in the firing position of the piston. Also, the muzzle end of ,slot 72 is proximate an insert or stop 74 located at the left end or muzzle end of barrel 14.

Sleeve 17 substantially encloses the barrel along the barrel portion of the housing from the breechblock to the location where the barrel is pivotally engaged, assuming the barrel is in alignment with breechblock 16 as illustrated in FIG. 1. To be more exact, the sleeve 17, which includes a retractor portion 76, extends from horizontal pin 124 to slightly beyond the breech end of barrel 14, When the tool is in the position illustrated in FIG. 1. When the tool is cocked by depressing muzzle 15 against a workpiece, wall, or the like, the sleeve, of course, moves rearwardly as sear 44 becomes positioned over trigger bar 54.

The sleeve 17 is provided with a handle 78, suitably formed of plastic, positioned at a location close to the breech end of sleeve 17. Handle 78 is semicircular in configuration as illustrated in FIG. 3 for fitting around the upper portion of sleeve 17. An internally threaded metal insert 126 is brazed to sleeve 17, and handle 78 is provided with a matching vertical bore for receiving insert 126. The upper portion of the vertical bore in handle 78 is countersunk to match the head of securing screw 128 which holds handle 78 against sleeve 17. In addition, handle 78 is also desirably adhered to metal sleeve 17 with a suitable plastic-to-metal bonding material.

As has been mentioned, in its normal position sleeve 17 extends from where the barrel is pivotally engaged to a location proximate the breech end of the barrel. The positioning of handle 78 at approximately the latter location gives the operator of the tool more convenient or closer access to a handle for retracting the captive piston, 22, and provides a direct pull on the captive piston during the retracting operation.

In barrel portion 12 of the housing, substantially under handle 78, there is located a magnet 130 normally held in position by a horizontal pin 132 extending through the magnet and into the housing. The purpose of this magnet is to attract and normally hold the sleeve 17 carrying the barrel so that the sleeve and barrel will not pivot away from the housing unless such action is desired. Thus, magnet 130 normally secures barrel 14 in its position shown in FIG. 1, unless the barrel is to be upraised, e.g. by means of handle 78.

The sleeve 17 includes piston retractor portion 76 carried by the barrel at the muzzle end of the sleeve. This piston retractor portion comprises a ring, slidably mounted on the exterior of the cylindrical barrel, the ring being joined to or unitary with the remainder of sleeve 17. Retractor portion 76 includes a member 82 comprising a dog for engaging piston head portion 27 as when the piston 22 has moved toward the muzzle end of the barrel. As illustrated in FIG. 5, barrel 14 may be pivotally upraised by pivoting around its forward location, after which the sleeve 17 may be moved to the right by means of handle 78 to slide retractor portion 76 to the right. Member 82 engages head portion 27 as retractor portion 76 is moved to the right, bringing with it piston 22 until the piston is returned to the right end or breech end of barrel 14. Then, sleeve 17 including retractor portion 76 is moved to the left-hand position illustrated in the drawings, and indeed must be before barrel 14 can be returned to a position in alignment with power plug 18. Sleeve 17 in its extended position, as indicated by broken lines in FIG. 5, extends beyond breechblock 16, and the breech portion 13 of the housing, preventing return of barrel 14 to its firing position. Moreover, the barrel portion of the housing includes wedge-shaped recess 92 for receiving a lower wedge-shaped portion 94 of the retractor portion only when the retractor portion is returned to its left-hand position. It is noted the retractor portion 76 is always removed out of the way of the movement of piston 22 when the tool is in firing position, thereby avoiding danger to the operator of the tool from undesired movement of retractor portion 76 and sleeve 17 when the tool is fired.

Lower wedge-shaped portion 94 of retractor 76 carries member 82 in a vertical slot 96 at the middle thereof, with the L-shaped member 82 being secured in the slot at its rearward end by means of horizontal pin 98 and at its forward end by horizontal pin 100. Wedge-shaped portion 94 is prevented from moving forward of its position in FIG. 1 relative to the barrel portion of the housing, i.e. when the tool is in an uncocked position, by means of horizontal pin 124. Horizontal pin 124 thus acts as a forward stop for barrel 14 and sleeve 17.

When the tool is fired, a power load explodes and combustion explosion gases enter bore 20 of barrel 14 forcing piston 22 to the left. As head portion 25 moves past the breech end of slot 72, these gases are vented along slot 72 within sleeve 17 and leave around retractor portion 76. Sleeve 17 suitably encloses barrel 14 circumferentially therearound completing a muffler enclosure acting to reduce the audible report produced by firing the tool.

Piston 22 is provided with an ejector 86 which may protrude into chamber 36 for ejecting power load or cartridge 88. The ejector 86 is tapered at its rearwardmost end. This tapered configuration acts to guide explosion gases along the chamber with minimum lateral deflection of such gases during firing of the tool to prevent chamber erosion. This construction is more fully described in the copendrrng application of Yung Shing Hsu entitled, Chamber Erosion Preventing Powder Actuated Tools, Ser. No. 675,140 filed Oct. 13, 1967, and assigned to the assignee of the present invention.

The captive piston 22 is tapered between head 24 and ram or plunger 26, and this tapered portion and head 24 have a low hardness and high ductility as compared with a high hardness and little or no ductility of stop 74. The hard metal stop 74 includes a long cylindrical entrance bore 114 and a frustoconical die portion 116. The bore 114 serves to slidably receive the muzzle end of the piston head 24, to the left of head portion 27, should the captive piston 22 be overdriven so that ram 26 extends outwardly at the left of muzzle 15. Should the piston thus be overdriven, piston energy is dissipated by extruding, by frustoconical die portion 116, the tapered portion of the captive piston 22. The construction allows the dissipation of energy of an overdriven piston without damage to the captive piston inasmuch as bore 114 laterally supports the captive piston during overdriving so as to prevent bending of the piston. This energy-dissipating mechanism is further described and claimed in the copending application 796,980 of Yung Shing Hsu and Raymond V. Pomeroy, filed Feb. 6, 1969 and assigned to the assignee of the present invention.

In the general operation of the tool according to the present invention, a fastener device is inserted in muzzle 15, and the user grasps a handle portion or grip 118 and forces the fastener device against a workpiece such as a masonry wall or the like. Urging the tool against a workpiece brings about full contact between power plug 18 and breechblock 16, and further urges the breechblock rearwardly of the tool into a cocked position, i.e. placing sear 44 above trigger bar 54. The trigger 60 may now be compressed raising sear 44 such that firing pin 42 is driven to the left exploding a cartridge or other power load in chamber 36. Explosive gases enter the inner bore of barrel 14 behind the head 24 of the captive piston driving the captive piston to the left and forcing the fastener device into the workpiece. As hereinbefore mentioned, explosive gases leave through slot 72 as the head portion 25 passes the breech end of slot 72 from what may be considered a combustion chamber inside the barrel to the right of slot 72 in FIG. 1. These gases leave directly through the length of slot 72 within sleeve 17. It should be noted the tool cannot be cocked against a workpiece and then removed from the workpiece, with the barrel being manually held in a cocked position, because the major portion of the barrel is substantially inaccessible within sleeve 17 To reload the tool, and return the captive piston to firing position, the barrel is moved to the left as by grasping muzzle 15, and the breech end thereof is pivoted upwardly by raising the same with handle 78. In practice, the tool may also be grasped by grip 118 and snapped in a downward direction causing the barrel 14 to lower and pivot so that the breech end of the barrel including power plug 18 tilts away from the breechblock. With the barrel in the out-tilted position, handle 78 mounted on sleeve 17 is grasped and pulled rearwardly. As a result, member 82 engages the outer edge of head portion 27 pulling the piston 22 to the right, back to a firing position. The movement of the piston, as head portion 25 reaches the breech end of slot 72, may force shell or power load 88 from chamber 36. If ejection is not accomplished by air pressure, the ejector contacts the cartridge for forcibly removing the same. Rearward movement of sleeve 17 and barrel 14 is limited by contact of member 82 against head portion 27 of the completely retracted piston. The sleeve and retractor portion are then returned to their forwardmost position by means of handle 78, and a new cartridge or power load is inserted in chamber 3-6. The barrel 14 is then pivoted back into alignment with breechblock 16 for the next operation. It is seen that the operation of the tool according to the present invention is simple, and construction thereof is compact. Since the weight of the tool is well balanced, the tool is easy to handle.

The enclosure of the barrel 14 in sleeve 17, extending substantially along the barrel portion of the housing, prevents retention of the tool in a cocked position when the same is not being urged against a workpiece. Thus, since the barrel is covered, it is substantially impossible to force the muzzle against a workpiece and then remove the muzzle from a workpiece while manually holding the barrel in cocked position. Therefore, accidental or intentional firing of the tool, other than into a solid workpiece or the like, is avoided.

Moreover, the elongated sleeve locates handle 78 toward the breech end of the tool, permitting easier access to the handle for retracting the captive piston from its fired to its firing position. This location of the handle not only provides for more convenient operation, but also has been found to enable a more satisfactory longitudinal retracting pull on the captive piston. Less force is frequently required because less binding can take place as compared with an instance where retracting handles are located at the side or toward the muzzle end of the tool.

The construction of the tool according to the present invention employing a sleeve surrounding the barrel also provides a simple and efficacious means of preventing the repositioning of the barrel in alignment with the breechblock until the piston retractor is returned to its forward position. That is, the sleeve 17 simply extends beyond the breechblock until the retractor portion is returned to a location out of the normal path of captive piston 22.

It should be noted that when the tool is urged against a workpiece, retractor portion 76 is automatically urged to the rear of wedge-shaped recess 92, assuming the retractor portion 76 is not already in such position. With the tool forced against a workpiece, the retractor portion 76 is held in position between the breech end of recess 92 and the muzzle end of slot 72. The muzzle end of slot 72 engages the inwardly extending portion of member 82. Therefore, when the tool is fired, no undesired movement of retractor portion 76 or sleeve 17 will take place. It should be noted that even if the piston 22 should be overdriven into stop 74, the edge of head portion 27 will not strike or move member 82, when the retractor portion 76 is in its locked position between the edges of recess 92 and slot 72.

- I claim:

1. In a powder actuated tool including a housing, a breechblock carried by a breech portion of the housing, a barrel supported in cradled relation by a barrel portion of the housing when said barrel is in a first position in substantial alignment with said breechblock, a captive piston longitudinally slidable within said barrel, and a piston retractor for moving said piston to a firing position toward the breech end of said barrel, said barrel being pivotally engaged by the barrel portion of said housing at a location toward the muzzle end of said barrel so that the breech end of said barrel can be upraised away from said breechblock into a loading position,

the improvement comprising:

sleeve means slidably carried by said barrel and extending, when said barrel is in a first position in substantial alignment with said breechblock, substantially from said breechblock to said location where said barrel is pivotally engaged,

said piston retractor comprising a portion of said sleeve means toward the muzzle end of said sleeve means,

and handle means carried by said sleeve means proximate the breech end of said sleeve means for sliding said sleeve means partially off the breech end of said barrel to move said piston retractor and piston into said firing position.

2. The tool according to claim 1 wherein said barrel is provided with a longitudinal slot ending short of the breech and muzzle ends of said barrel, and wherein said piston retractor includes means extending through said longitudinal slot in said barrel for engaging the head of said piston at the muzzle end thereof.

3. The tool according to claim 1 wherein said sleeve means substantially encloses said barrel as said barrel is cradled in supporting relation by said housing, said sleeve means being coaxially interposed between said barrel and the barrel portion of said housing.

4. The tool according to claim 1 including a substantially vertical pin member carried by said barrel at said location toward the muzzle end of said barrel, said pin extending from the lower side of said barrel,

the barrel portion of the housing being provided with a longitudinal slot means through which said vertical pin member extends, said longitudinal slot means having an effective length permitting longitudinal sliding movement of the barrel from nonengagement to full engagement with the breechblock plus rearward movement of the breechblock into a cocked position.

5. The tool according to claim 4 including a horizontal pin normally transversely positioned in the barrel portion of said housing for effectively defining the rearward extent of said longitudinal slot means and the longitudinal movement of said barrel,

said horizontal pin being removable for disassembly of said tool, permitting movement of said vertical pin upward and outward to the rear of said tool.

6. The tool according to claim 2 wherein said barrel portion of the housing is semicircularly channel-shaped and open upwardly,

said barrel portion of the housing being provided with an arched barrel retaining member proximate said location toward the muzzle end of the barrel for substantially enclosing the upper side of the barrel at such location,

said arched barrel retaining member having an inner semicircular surface for substantially matching the barrel in an upraised position thereof and for limiting the upward movement of the barrel.

7. The tool according to claim 2 wherein said sleeve means substantially encloses said barrel from said breechblock to said location where said barrel is pivotally engaged, at a time when said barrel is in a first position in substantial alignment with said breechblock, said longitudinal slot in said barrel as closed by said sleeve means forming a muflier enclosure for said tool acting to reduce the audible report produced by firing the tool as explosion gases pass along said slot toward the piston retractor.

8. The tool according to claim 1 wherein said barrel portion of the housing below the handle means carried by the sleeve means is provided with a magnet secured to the housing for attracting and removably holding said sleeve means when said barrel is in said position in substantial alignment with said breechblock.

9. A powder actuated tool comprising:

a housing including a rearward breech portion and a forward barrel portion,

a breechblock carried by said breech portion,

an elongated barrel supported by the barrel portion of said housing,

a sleeve slidably carried on said barrel along the barrel portion of said housing and extending substantially to said breechblock, when said barrel is in a first position in substantial alignment with said breechblock, said sleeve being cradled by said barrel portion of said housing,

said barrel being pivotally engaged by the barrel portion of said housing at a location toward the muzzle end of said barrel so that the breech end of said barrel and the sleeve carried thereby can be upraised away from said breechblock into a loading position, a captive piston longitudinally slidable within said barrel and movable in response to explosion of a power load for driving a fastener element into a workpiece at the muzzle end of said barrel,

said sleeve including a piston retractor portion slidably carried by said barrel and normally located at the muzzle end of the barrel, said retractor portion including a member for engaging said piston, and

a handle means mounted on said sleeve and manually engageable for moving said piston retractor and said piston to a firing position toward the breech end of said barrel when said barrel and sleeve are upraised away from said breechblock.

10. The tool according to claim 9 wherein said sleeve substantially encloses the barrel approximately between said breechblock and said location where the barrel is pivotally engaged.

11. The tool according to claim 9 wherein the said 9 10 handle means is secured on the upper side of said sleeve means for providing relative movement between said proximate the breech end of said sleeve. barrel and breechblock so that said sleeve is movable 12. A powder actuated tool comprising: past said breechblock to move said piston to a firing a housing including a rearward breech portion and a position toward the breech end of said barrel.

13. The tool according to claim 12 wherein said handle means is located proximate the breech end of said sleeve.

forward barrel portion,

a breechblock carried by the breech portion,

a barrel carried by the barrel portion, said barrel slidably carrying a sleeve substantially enclosing a maferences C ed jor portion of said barrel and normally extending sub- UNITED STATES PATENTS stantially to the position of said breechblock, 1 a captive piston longitudinally slidable within said barg i 2 rel and movable in response to explosion of a power emp 6 et a load for driving a fastener element into a workpiece 3172119 3/1965 Siddons 227 8 at the muzzle end of Said barrel 3,357,617 12/1967 Osborne 227-10 3,409,197 11/1968 Brack 227-10 said sleeve including piston retractor means for engag- 15 ing said piston within said barrel and returning the same to a firing position toward the breech end of WENDELL BURNS Pnmary Exammer said barrel, C1 R handle means mounted on said sleeve and manually engageable for moving said piston retractor means and said piston, and