# Patent

## Title
Fastening tool with automatic feeding of wire-collated fasteners

## Abstract

A fastening tool with a magazine assembly for holding and dispensing collated fasteners. The magazine assembly includes a canister and a door that is hingedly coupled to a nosepiece. The canister includes a stationary portion and a movable portion that may be moved relative to the stationary portion to permit access to an interior of the canister, e.g., for loading the fasteners into the canister. The door cannot be moved from a closed position to an open position and vice versa without first opening the canister. A method for loading a magazine is also provided.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
Other features of the present invention are discussed and claimed in the following commonly assigned U.S. Patent Applications: U.S. application Ser. No. 10/852,986 entitled “Depth Adjustment Mechanism”, which issued as U.S. Pat. No. 6,883,696 on Apr. 26, 2005, U.S. application Ser. No. 10/852,990 entitled “Height Adjustable Coil Nail Canister”, and U.S. application Ser. No. 10/852,979 entitled “Anti-Slip Shingle Grip For Fastening Tool” which issued as U.S. Pat. No. 6,948,647 on Sep. 27, 2005.
INTRODUCTION
The present invention generally relates to fastening tools including nailers. More particularly, the present invention generally relates to magazine assemblies for fastening tools and methods for loading magazine assemblies.
Coil nailers are known in the art for performing tasks such as attaching asphalt shingles to a roof or for attaching vinyl siding to an exterior wall of a building. Such nailers typically include a drum for storing a coil of collated fasteners and a feed mechanism for feeding the fasteners into nosepiece of the fastening tool. While the known coil nailers are suitable for their intended purpose, we have found that they are nonetheless susceptible to improvement.
For example, the feeding of the fasteners into the nosepiece is often times a slow and/or tedious task and moreover, it is often times not readily apparent to the user of such fastening tools how the magazine assembly, etc. is to be opened or arranged to initially load a coil of fasteners into the magazine assembly and/or feed the fasteners into the nosepiece. Accordingly, there remains a need for an improved magazine assembly.
SUMMARY
In one form, the present teachings provide a fastening tool that includes a housing assembly having a nosepiece and a magazine assembly that is coupled to the housing assembly. The magazine assembly includes a canister, a door structure, a feed pawl and a follower structure. The canister is configured to hold a plurality of collated fasteners and has a first canister portion and a second canister portion that is movable relative to the first canister portion between a closed position and an open position. The door structure carries one of the feed pawl and the follower structure and is coupled to the nosepiece so as to be pivotally movable between a first position, which substantially clears the other one of the feed pawl and the follower structure, and a second position wherein the feed pawl and the follower structure may cooperate with one another to sequentially feed the collated fasteners into the nosepiece. A portion of the second canister portion overlies the door structure when the door structure is positioned in the first position and the second canister portion is positioned in the closed position.
In another form, the present teachings provide a method that includes: providing a fastening tool with a housing assembly and a magazine assembly, the housing assembly having a nosepiece, the magazine assembly including a canister, a door structure, a feed pawl and a follower structure, the canister having a first canister portion and a second canister portion that is movable relative to the first canister portion between a closed position and an open position, the door structure carrying one of the feed pawl and the follower structure and being coupled to the nosepiece so as to be pivotally movable between a first position, which substantially clears the other one of the feed pawl and the follower structure, and a second position; opening the magazine assembly by first positioning the second canister portion in the open position and thereafter moving the door structure into the first position; inserting a coil of collated fasteners into an interior of the canister; arranging an end of the coil of collated fasteners over the other one of the feed pawl and the follower structure; and closing the magazine assembly by first moving the door structure into the second position and thereafter positioning the second canister portion in the closed position; wherein positioning of the door structure into the second position permits the feed pawl and the follower structure to cooperate with one another to sequentially feed the collated fasteners into the nosepiece.
In yet another form, the present teachings provide a fastening tool with a housing assembly, which has a nosepiece, and a magazine assembly that is coupled to the housing assembly. The magazine assembly includes a feed pawl and a feed cylinder assembly. The feed cylinder assembly includes a feed piston assembly that is operable for translating the feed pawl relative to the nosepiece to sequentially feed collated fasteners into the nosepiece. The feed piston assembly includes a primary feed piston and a secondary feed piston. The secondary feed piston is positionable in an extended position and a retracted position that is relatively further from the nosepiece than when the secondary feed piston is positioned in the extended position. The primary feed piston is translatable between a first position and a second position when the secondary feed piston is positioned in the extended position. The primary feed piston is translatable between the first position and a third position when the secondary feed piston is positioned in the retracted position. The third position is relatively further from the nosepiece than the second position.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.



BRIEF DESCRIPTION OF THE DRAWINGS
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is a perspective view of a fastening tool constructed in accordance with the teachings of the present invention;
FIG. 2 is an exploded perspective view of a portion of the fastening tool of FIG. 1 illustrating the nosepiece and magazine assembly in greater detail;
FIG. 3 is a left elevation view of the nosepiece;
FIG. 4 is an exploded perspective view in partial section of a portion of the nosepiece and magazine assembly;
FIG. 5 is a sectional view taken through a portion of the fastening tool of FIG. 1;
FIG. 6 is a schematic illustration of a portion of the fastening tool of FIG. 1 illustrating a pneumatic circuit for translating the feed piston assembly;
FIG. 7 is a sectional view of a portion of the fastening tool of FIG. 1 illustrating the follower pawl assembly as coupled to the nosepiece;
FIG. 8 is a sectional view of a portion of the fastening tool of FIG. 1 illustrating the canister in a closed position and engaged to the nosepiece;
FIG. 9 is a partial right elevation view of the fastening tool of FIG. 1;
FIG. 10 is a perspective view of a portion of the fastening tool of FIG. 1 illustrating the nosepiece and magazine assembly in an open condition;
FIG. 11 is a sectional view taken through a portion of the magazine assembly and illustrating the feed cylinder, the feed piston assembly and the feed pawl assembly in greater detail;
FIG. 12 is a perspective view of a portion of the magazine assembly illustrating the follower structure in greater detail;
FIG. 13 is a schematic illustration of an alternately constructed fastening tool illustrating another pneumatic circuit for translating the feed piston assembly;
FIGS. 14 and 15 are schematic illustrations similar to that of FIG. 13 but illustrating two additional pneumatics circuit for translating the feed piston assembly;
FIG. 16 is a longitudinal cross-section of a double-acting double cylinder for translating the feed pawl; and
FIGS. 17 through 20 are alternately constructed double-acting double cylinders for translating the feed pawl.



DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS
With reference to FIG. 1 of the drawings, a fastening tool constructed in accordance with the teachings of the present invention is generally indicated by reference numeral 10. The fastening tool 10 may include a housing assembly 12 and a magazine assembly 14. The housing assembly 12 may include a housing 16, which may be formed from any appropriate material including aluminum, magnesium and/or plastic, a nosepiece 18, and a contact trip 20. The housing 16 conventionally houses a trigger 22 and a motor 24 with a driver 26 that may be selectively translated along an axis 28 to drive a fastener into a workpiece (not shown). In the particular example provided, the housing 16 includes a central portion 30 and an upper end cap 32, which is configured to close off an upper end of the central portion 30, while the nosepiece 18 includes an upper flange 34 that is configured to close off a lower end of the central portion 30. Conventional fasteners 38, such as socket head cap screws, may be employed to fixedly but removably couple the upper end cap 32 and nosepiece 18 to the central portion 30. While not specifically shown, those of ordinary skill in the art will appreciate that conventional gaskets or seals may be employed to seal the interfaces between the upper end cap 32 and the central portion 30 and between the central portion 30 and the nosepiece 18.
With reference to FIGS. 2 and 3, the nosepiece 18 may include the upper flange 34, a barrel 50, a nosepiece hinge mount 52, a feed cylinder 54, first and second feed cylinder conduits 56 and 58, respectively, a magazine latch post 60, a canister latch post 62 and a cover hinge mount 64. The barrel 50 may include a first portion 70, which may be disposed adjacent the upper flange 34, a second portion 72 that may be disposed on a side of the first portion 70 opposite the upper flange 34, and an interior cavity 76 that may extend through the first and second portions 70 and 72. The first portion 70 may have a closed perimeter that encloses the interior cavity 76, whereas the second portion 72 has an open perimeter that forms an opening 78 that permits the fasteners (not shown) to be fed into the interior cavity 76. The barrel 50 may also include one or more guides 80 that guide or restrict the movement of a lower contact trip 80 along the barrel 50.
The nosepiece hinge mount 52 may include a pair of trunnion mounts 84 that extend from the barrel 50 proximate the opening 78 in the second portion 72. The first and second feed cylinder conduits 56 and 58 may couple the feed cylinder 54 to the upper flange 34, while first and second support legs 86 and 88, respectively, may couple the feed cylinder 54 to the barrel 50. The first support leg 86 may define a guide track 90 that may be configured to receive the heads (not shown) of the collated fasteners (not shown) as the collated fasteners are fed into the barrel 50.
The feed cylinder 54 may include a feed cylinder structure 100 and a feed cylinder end cap 102. The feed cylinder structure 100 may define a body portion 110, a first flange 112 and a second flange 114. The body portion 110 may be generally cylindrically shaped and may define a cylindrical bore 116. The first flange 112 may be located on a first end of the body portion 110 and may define a rod aperture 118 and a seal recess 120 that are concentric with the bore 116. The second flange 114 may include a pair of bosses 122 that may be employed to fixedly but removably couple the feed cylinder end cap 102 to the feed cylinder structure 100. The feed cylinder end cap 102 may be configured to extend an end of the bore 116 opposite the first flange 112. In the example provided, the feed cylinder end cap 102 includes a body 130 that defines a bore 132 that is somewhat smaller in diameter than bore 116. The body 130 may be configured to be partially received into the bore 116 so that the bore 132 and the bore 116 are concentric with one another.
With reference to FIGS. 1 and 4 through 6, the first feed cylinder conduit 56 may be configured to supply compressed air from the housing 16 to a first end of the feed cylinder structure 100 while the second feed cylinder conduit 58 is configured to supply compressed air from the housing 16 to a second end of the feed cylinder structure 100. The housing 16 may include a first feed channel 140, which may be coupled in fluid communication to the first feed cylinder conduit 56 and configured to receive compressed air when a piston 142 associated with the motor 24 is moved to a returned position after the driving of a fastener, and a second feed channel 144, which may be coupled in fluid communication to the second feed cylinder conduit 58 and coupled to a main reservoir 146 that supplies compressed air to a trigger valve 148 that is associated with the trigger 22. As the first and second feed channels 140 and 144 are spaced laterally apart from one another, one of the first and second feed cylinder conduits 56 and 58 (e.g., the first feed cylinder conduit 56) may include a portion 150 that is recessed into an upper side of the upper flange 34 as is best shown in FIG. 2. Configuration in this manner permits the portions of the first and second feed cylinder conduits 56 and 58 that are located between the upper flange 34 and the feed cylinder structure 100 to be stacked upon one another for improved strength and reduced casting complexity.
With reference to FIG. 7, the magazine latch post 60 may be coupled to the first support leg 86 and may include a first ramp 160 and a second ramp 162. With reference to FIG. 8, the canister latch post 62 may also be coupled to the first support leg 86 and may include a tapered latch contact 170 and an abutting surface 172. The magazine latch post 60 and the canister latch post 62 will be discussed in further detail, below.
With reference to FIGS. 2 and 9, the cover hinge mount 64 may include a pair of trunnion mounts 180 that may be coupled to the second support leg 88 on a side of the nosepiece 18 opposite the nosepiece hinge mount 52. The cover hinge mount 64 may be configured to cooperate with a hinge pin 182 to pivotally couple a cover 184 to the nosepiece 18 in a manner that shrouds a portion of the nosepiece 18 between the first flange 112 of the feed cylinder structure 100 and the barrel 50. The cover 184, which may be positioned in an open position and a closed position (which is illustrated in FIG. 9), may be maintained in the closed position by any suitable means. In the example provided, a threaded fastener 188 is inserted through the cover 184 and threadably engaged to the first support leg 86 to maintain the cover 184 in the closed position.
In FIGS. 1, 2, 10 and 11, the magazine assembly 14, which may be coupled to the housing assembly 12, may be configured to house a plurality of fasteners and sequentially feed the fasteners into the nosepiece 18. The magazine assembly 14 may include a canister 200 for holding coiled, collated nails 500 and a feed mechanism 202, which may include a feed pawl assembly 206 and a follower pawl assembly 208. The canister 200 may include a first canister portion 212, a second canister portion 214, a hinge pin 216, a latch bracket 218 and a canister latch 220. The first canister portion 212 may be fixedly coupled to the housing assembly 12. In the particular example provided, the first canister portion 212 includes a first mount 224, which may be fixedly but removably coupled to a handle 226 of the housing 16 via a threaded fastener 228, and a second mount 234, which may be fitted over a portion of the feed cylinder end cap 102. A vent hole 236 may be formed in the second mount 234 to permit air to enter or exit an open end of the bore 132 in the feed cylinder end cap 102.
The second canister portion 214, which may be formed of an appropriate plastic material, may be pivotally coupled to the first canister portion 212 so that the second canister portion 214 may be moved between a first position, which may substantially close an interior portion of the canister 200, which is illustrated in FIG. 1, and a second position, which may generally clear the first canister portion 212 so that coiled, collated nails 500 may be loaded into the interior portion 240 of the canister 200 as illustrated in FIG. 10. The second canister portion 214 may include an ear 244, which extends toward the feed pawl assembly 206 and overlies a portion of the follower pawl assembly 208 when the fastening tool 10 is operated, and a latch mount 248.
Returning to FIG. 8, the latch bracket 218, which may be formed of a relatively high-strength and impact-resistant material such as steel, may be coupled to the ear 244 and may have a generally U-shaped portion 250, which may be configured to abut the opposite end faces 252 of the ear 244, and one or more hook portions 254.
The canister latch 220 may include a latch structure 260, a latch pivot pin 262 and a latch spring 264. The latch structure 260 may include a latch member 270, and a latch handle 272 and may be pivotally coupled to the latch mount 248 formed on the second canister portion 214 by the latch pivot pin 262. The latch pivot pin 262 may also be employed to couple or aid in coupling the latch bracket 218 to the second canister portion 214. In the example provided, the latch pivot pin 262 extends through the hook portions 254 to secure an end of the latch bracket 218 opposite the ear 244 to the latch mount 248. The latch spring 264 biases the latch structure 260 about the latch pivot pin 262 in a predetermined rotational direction.
The latch member 270 is configured to cooperate with the canister latch post 62 to releasably secure the second canister portion 214 in the closed position. In this regard, the canister latch post 62 is complementary to the latch member 270 so that when the second canister portion 214 is urged toward the closed position, the tapered latch contact 170 interacts with the latch member 270 to cause the latch member 270 to rotate in a rotational direction opposite the rotational direction in which it is biased by the latch spring 264. When a confronting surface 280 of the latch member 270 passes the abutting surface 172 of the canister latch post 62, the latch spring 264 urges the latch member 270 in a rotational direction so that the confronting surface 280 of the latch member 270 abuts the abutting surface 172 of the canister latch post 62. A user may pivot the latch handle 272 about the latch pivot pin 262 in the rotational direction opposite the rotational direction in which the latch structure 260 is biased by the latch spring 264 to position the confronting surface 280 of the latch member 270 into a position that clears the abutting surface 172 so that the second canister portion 214 may be moved from the closed position to the open position.
In FIGS. 2 and 4, the feed pawl assembly 206 of the feed mechanism 202 may include a feed piston assembly 300, a feed pawl 302, a hinge pin 304 and a biasing spring 306. The feed piston assembly 300 may include a feed piston 310, a feed rod 312, and first, second and third seals 314, 316 and 318, respectively. The feed piston 310 may include a first body portion 320, a necked-down portion 322, and a second body portion 324. The first body portion 320 may be formed of a first diameter and may include a pair of seal grooves 326 for receiving the first seals 314, which may be O-rings. The first body portion 320 may be slidably received in the bore 132 of the feed cylinder end cap 102. The necked-down portion 322 may be located between the first and second body portions 320 and 322 and may be smaller in diameter than the first body portion 320 and larger in diameter than the feed rod 312. The second body portion 324 may be disposed on a side of the necked-down portion 322 opposite the first body portion 320 and may include a pair of seal grooves 328 that are configured to receive the second seals 316, which may be O-rings. The second body portion 324 may be slidably received in the bore 116 in the feed cylinder structure 100.
The feed rod 312 may be coupled to the second body portion 324 and may include a flat 340, which may be formed onto an end of the feed rod 312 opposite the second body portion 324, and a pivot pin aperture 342 that may be formed through the feed rod 312 in a direction that may be generally parallel to the flat 340. A spring bore 344 may be formed into the feed rod 312 in an orientation that is generally perpendicular to both the flat 340 and the pivot pin aperture 342. The feed rod 312 may be received into the rod aperture 118 and extend through the first flange 112 of the feed cylinder structure 100. The third seal 318 may be disposed in the annular recess 120 that is formed in the first flange 112 and may sealingly engage both the first flange 112 of the feed cylinder structure 100 and a perimeter of the feed rod 312.
With reference to FIGS. 2 and 11, the feed pawl 302 may include a backing plate 360, first and second guide tabs 362 and 364, respectively, and a pair of trunnion mounts 368. The backing plate 360 may include a primary feed tooth 370 and a secondary feed tooth 372, which may be formed on a first side of the backing plate 360, as well as a spring guide 374 on a second, opposite side. The primary and secondary feed teeth 370 and 372 may be spaced apart by a distance that permits one of the coiled, collated fasteners to be received therebetween. The first and second guide tabs 362 and 364 may extend laterally from the opposite lateral sides of the backing plate 360 and may be configured to engage first and second guide rails 380 and 382, respectively, that may be formed on a rear side of the first and second support legs 86 and 88, respectively. The trunnion mounts 368 may extend from a side of the backing plate 360 opposite the primary and secondary feed teeth 370 and 372 and may serve as a means for mounting the hinge pin 304 so that the feed pawl 302 may be pivotably coupled to the feed rod 312. More specifically, the feed rod 312 may be disposed between the trunnion mounts 368 such that a flat 340 that is formed on the feed rod 312 may generally face a rear side of the backing plate 360 and a pivot pin aperture 342 that is formed through the feed rod 312 may be aligned to a pin aperture 384 in the trunnion mounts 368. The hinge pin 304 may be disposed through pin apertures 384 and the pivot pin aperture 342 to thereby pivotally couple the feed pawl 302 to the feed piston assembly 300. The biasing spring 306, which may be located in a blind spring bore 344 that is formed in the feed rod 312 and abut a rear face of the backing plate 360 where it is disposed over the spring guide 374, may bias the feed pawl 302 about the hinge pin 304 toward second body portion 324 of the feed piston assembly 300.
With the feed piston assembly 300 disposed in the feed cylinder 54 and the feed pawl 302 coupled to the feed rod 312 of the feed piston assembly 300 and supported by the first and second support legs 86 and 88, compressed air may be routed through the first and second feed cylinder conduits 56 and 58 to effect movement of the feed pawl 302 relative to the barrel 50. For example, compressed air may be routed through the first feed cylinder conduit 56 and directed to the bore 116 in the feed cylinder structure 100 at a location between the second and third seals 316 and 318, which may drive the feed piston assembly 300 (and the feed pawl 302) away from the barrel 50. Compressed air may also be routed through the second feed cylinder conduit 58 and directed to the bore 116 in the feed cylinder structure 100 at a location between the first and second seals 314 and 316, thereby driving the feed piston assembly 300 (and feed pawl 302) toward the barrel 50. The stroke of the feed piston assembly 300 may be slightly larger than a spacing between an adjacent pair of the collated fasteners (not shown).
Significantly, ambient air is not input directly into the feed cylinder 54 when the feed piston assembly 300 is reciprocated to feed the collated fasteners 94 into the barrel 50. Rather, the air that is input to the feed cylinder 54 (as well as the air that is exhausted from the feed cylinder 54) is routed through the housing assembly 12 (FIG. 1). Consequently, a feeding system constructed in accordance with the teachings of the present invention is much less susceptible to damage due to the entraining of dirt and debris into the air that is input to the feed cylinder 54.
We have found, too, that the use of a plurality of the first and second seals 314 and 316 on the feed piston 310 aids in both the retention of lubrication in the feed cylinder and the supporting and guiding of the feed piston 310 as it is reciprocated. The retaining of lubrication in the feed cylinder 54 greatly slows the rate at which the seals 314 and 316 wear. Moreover, improved support and guiding of the feed piston 310 reduces side-loading of the feed piston assembly 300 which not only reduces the overall wear rate of the seals 314, 316 and 318, the feed pawl 302 and the first and second guide rails 380 and 382, but also reduces or eliminates uneven wear on the seals 314, 316 and 318.
Returning to FIG. 2, the follower pawl assembly 208 may include a pair of trunnion mounts 400, a follower door 402, a follower structure 404, a follower pivot pin 406, a follower biasing spring 408, a pivot pin biasing spring 410 and a cover 412. The trunnion mounts 400 may be coupled to the follower door 402 and may cooperate with the trunnion mounts 84 of the nosepiece hinge mount 52 and a hinge pin 432 to provide a means by which the follower pawl assembly 208 may be pivotally but removably coupled to the nosepiece 18.
The follower door 402 may include a barrel portion 420, a frame structure 422, a stop member 424, a lifting tab 426 and a retaining tab 428. The barrel portion 420 may be configured to close a portion of the opening 78 in the barrel 50 when the follower pawl assembly 208 is positioned in a closed position. In the example provided, the lower contact trip 80 wraps about the barrel portion 420 when the contact trip 20 is urged upwardly into a position that activates the trigger or otherwise permits a user to activate the fastening tool 10 to install a fastener. The frame structure 422 may be coupled to the barrel portion 420 and/or the trunnion mounts 400 and may serve as a structure to which the follower structure 404, the follower pivot pin 406, the pivot pin biasing spring 410 and the cover 412 may be mounted.
The stop member 424 may extend from the frame structure 422 and may be configured to contact a complementary stop 430, which may be formed on the magazine latch post 60 for example, to inhibit the follower door 402 from pivoting about the hinge pin 432 into a position that may inhibit the feeding of collated fasteners into the barrel 50. The retaining tab 428 and the lifting tab 426, which may be engaged by the finger or thumb of an operator when the follower pawl assembly 208 is to be pivoted about the hinge pin 432, may also be coupled to frame structure 422. As will be described in more detail below, the retaining tab 428 may be configured to cooperate with the canister 200 to inhibit the follower pawl assembly 208 from being moved from the closed position to the open position and from the open position to the closed position when the second canister portion 214 is in the closed position.
With additional reference to FIG. 12, the follower structure 404, which may be generally U-shaped, may be pivotally coupled to the frame structure 422 by the follower pivot pin 406. The follower structure 404 may include a plurality of follower teeth 440 and a stop member 442 that may be configured to contact the frame structure 422 to limit the amount by which the follower structure 404 may rotate outwardly from the frame structure 422 toward the feed pawl 302. The follower teeth may be configured to engage the collated fasteners (not shown) on a side opposite the feed pawl 302.
The follower biasing spring 408 may be disposed between the follower structure 404 and the cover 412, which may be removably coupled to the frame structure 422 via a threaded fastener 444. The follower biasing spring 408 may be configured to bias the follower structure 404 in a direction towards the feed pawl 302 when the follower pawl assembly 208 is positioned in the closed position.
The follower pivot pin 406 be configured to be received through apertures 450a and 450b that are formed in the frame structure 422 and the follower structure 404, respectively, and may include a head portion 460, a body portion 462 and an end portion 464. The head portion 460 may include a spring follower 466 and an abutting portion 468 which may be generally larger in size than the spring follower 466 or the body portion 462. The end portion 464 may be coupled to an end of the body portion 462 opposite the head portion 460 and may be a tapered or rounded shape.
With additional reference to FIG. 7, the pivot pin biasing spring 410 may be disposed about the spring follower 466 and abut both the head portion 460 and an L-shaped portion 470 of the cover 412. The pivot pin biasing spring 410 may exert a force onto the follower pivot pin 406 that urges the end portion 464 outwardly of the frame structure 422 so that it may serve as a detent that may cooperate with the magazine latch post 60 to retain the follower pawl assembly 208 in the closed position.
When the follower pawl assembly 208 is moved from the open position to the closed position (or from the closed position to the open position), the end portion 464 may cooperate with the magazine latch post 60 to shift the follower pivot pin 406 relative to the frame structure 422. More specifically, contact between the end portion 464 of the follower pivot pin 406 and the first ramp 160 as the follower pawl assembly 208 is being moved to the closed position (or with the second ramp 162 as the follower pawl assembly 208 is being moved to the open position) urges the follower pivot pin 406 into the frame structure 422. The force that is exerted by the pivot pin biasing spring 410 urges the follower pivot pin 406 outwardly so that contact between the follower pivot pin 406 and the magazine latch post 60 tends to maintain the follower pawl assembly 208 in the closed position.
With reference to FIGS. 2, 4 and 10, the magazine assembly 14 may be opened to load collated fasteners into the magazine assembly 14. In this regard, the canister latch 220 may be actuated so as to retract the latch member 270 from the canister latch post 62, the second canister portion 214 may be rotated about the hinge pin 216 to expose an interior portion of the canister 200, and the follower pawl assembly 208 may be rotated about the hinge pin 432 to the open position which substantially clears the follower pawl assembly 208 and the opening 78 in the barrel 50. A coil 500 of the collated fasteners 94 may be inserted into the canister 200 and an outer end 502 of the collated fasteners 94 may be strung towards the barrel 50 such that one of the collated fasteners 94 is disposed between the primary and secondary feed teeth 370 and 372. The follower pawl assembly 208 may be returned to the closed position and thereafter the second canister portion 214 may be closed so as to re-engage the canister latch 220 to the canister latch post 62.
With additional reference to FIGS. 1 and 6, when a source of compressed air 510 is coupled to the fastening tool 10, compressed air may be directed through the second feed channel 144 in the housing 16 and into the second feed cylinder conduit 58 where it is directed against the feed piston 310 in such a way that the feed pawl 302 is maintained in an extended position that is proximate the barrel 50. When the trigger 22 is depressed and the trigger valve 148 is actuated, the piston 142 is translated within the motor 24, thereby translating the driver 26 so that the driver 26 may impact and drive a fastener 94 located in the barrel 50 into a workpiece (not shown). When the piston 142 is translated to a drive position prior to the driving of the fastener 94, air within the motor 24 may be exhausted through the first feed channel 140 in the housing 16 and into the first feed cylinder conduit 56 where it may be directed against the feed piston 310 in such a way as to cause the feed pawl 302 to translate toward the feed cylinder 54.
The follower structure 404 may be biased toward the fastener 94 that is located between the primary and secondary feed teeth 370 and 372 and as such, the follower teeth 440 (FIG. 12) on the follower structure 404 may engage one of the fasteners 94 in the outer end 502, such as the fastener 94 that is located between primary and secondary feed teeth 370 and 372, to thereby inhibit movement of the fasteners 94 in the outer end 502 toward the canister 200 when the feed pawl 302 is translated toward the feed cylinder 54. The shape of the primary and secondary feed teeth 370 and 372 permits the feed pawl 302 to rotate about the hinge pin 304 in a direction away from the fasteners 94 so that the primary and secondary feed teeth 370 and 372 may skip over one set of adjacent fasteners 94. Thereafter, the biasing spring 306 urges feed pawl 302 outwardly toward the fasteners 94 so that a next fastener 94a is disposed between the primary and secondary feed teeth 370 and 372.
When the pressure of the air that is exhausted from the motor 24 in response to the returning of the piston 142 has subsided, the pressure of the air that is delivered through the second feed cylinder conduit 58 is sufficient to cause the feed piston assembly 300 to translate in a direction that returns the feed pawl 302 to a position proximate the barrel 50. The primary feed tooth 370 (and to a somewhat lesser extent, the secondary feed tooth 372) pushes the outer end 502 of the fasteners 94 toward the barrel 50. The follower biasing spring 408 permits the follower structure 404 to pivot about the follower pivot pin 406 so that the follower teeth 440 skip over the fastener 94 as the outer end 502 of the fasteners 94 is indexed toward the barrel 50.
While the fastening tool has been described thus far as including a double-acting feed cylinder that is fed from both a main drive reservoir (i.e., line air pressure) and the exhaust of the motor, those skilled in the art will appreciate that the invention, in its broader aspects, may be constructed somewhat differently. For example, the first feed cylinder conduit 56 may be coupled to the main drive reservoir 146 to continuously apply line air pressure to a first side of the feed piston 310 and the second feed cylinder conduit 58 may be coupled to the trigger valve 148 as is illustrated in FIG. 13. In this embodiment, the feed piston assembly 300 is normally maintained in a position proximate the barrel 50 and translates toward the feed cylinder 54 after the trigger valve 148 has been actuated.
As another example, the first feed cylinder conduit 56 may be coupled to a return reservoir 147 (i.e., a reservoir that is employed to store compressed air that is to be used to return the piston 142 after a fastener has been driven into a workpiece) and the second feed cylinder conduit 58 may be coupled to either the main drive reservoir 146 (FIG. 14) or to the trigger valve 148 (FIG. 15).
In the example of FIG. 16, the feed cylinder 54a may include a bore 116a, a first port 600, a second port 602, and a third port 604. The bore 116a may include a first bore portion 610 and a second bore portion 612 that may be relatively larger in cross-sectional area than the first bore portion 610. The first port 600 may intersect the first bore portion 610 at a first end of the feed cylinder 54a, the second port 602 may intersect the first bore portion 610 at an intermediate location, and the third port may intersect the second bore portion 612 at a second end of the feed cylinder 54a opposite the first end.
The feed piston assembly 300a may include a primary feed piston assembly 620 and a secondary feed piston assembly 622. The primary feed piston assembly 620 may include the feed rod 312a, a primary feed piston 650, a first seal 652 and a second seal 654. The first seal 652 may sealingly engage the feed rod 312a and the feed cylinder 54a, while the second seal 654 may be carried by the primary feed piston 650 and may sealingly engage the primary feed piston 650 and the perimeter of a first interior cavity 656 formed in the secondary feed piston 660.
The secondary feed piston assembly 622 includes a secondary feed piston 660, a third seal 662, a fourth seal 664, a fifth seal 668 and a sixth seal 670. The secondary feed piston 660 may include a body portion 674 and an end portion 676. A first vent channel 680 may be formed through the body portion 674 generally transverse thereto and a second vent channel 682 may be formed through the end portion 676 in a direction that is generally parallel to a longitudinal axis of the secondary feed piston 660. The third seal 662 may be carried by the body portion 674 and may be configured to form a seal between a the secondary feed piston 660 and the feed cylinder 54a at a location between the first and second ports 600 and 602. The fourth seal 664 may be carried by the secondary feed piston 660 and may form a seal between the body portion 674 and the feed cylinder 54a at a location along the first bore portion 610 between the second and third ports 602 and 604. The fifth seal 668 may be carried by the secondary feed piston 660 and may form a seal between the end portion 676 and the feed cylinder 54a at a location along the second bore portion 612 between the second and third ports 602 and 604. The sixth seal 670 may be carried by the secondary feed piston 660 and may sealingly engage a projection 690, which extends from the end portion 676, and the perimeter of a second interior cavity 692 formed in the primary feed piston 650. Configuration of the primary and secondary feed pistons 650 and 660 in this manner defines three distinct cavities 694, 696 and 698.
In operation, each of the first, second and third ports 600, 602 and 604 may be exposed to a supply of pressurized fluid (e.g., compressed air) so that the pressure in one of the ports may be substantially equal to the pressure in the other ports. As the end portion 676 of the secondary feed piston 660 is relatively larger in cross-sectional area than the body portion 674, fluid pressure drives the secondary feed piston 660 toward the first end 700 of the feed cylinder 54a. Likewise, as fluid pressure is applied via the second and third ports 602 and 604 over a cross-sectional area that is relatively larger than the area over which fluid pressure is applied via the first port 600, the primary feed piston 650 is also urged toward the first end 700 of the feed cylinder 54a. 
When a fastener is to be indexed into the barrel, the pressure of the fluid that is supplied via the second port 602 is reduced (e.g., the second port 602 may be vented to the atmosphere) by an amount that is sufficient to permit the pressure of the fluid that is provided by the first port 600 to urge the primary feed piston 650 away from the first end 700 of the feed cylinder 54 to thereby move the feed pawl over a next one of the collated fasteners. Contact between the primary feed piston 650 and the projection 690 that is formed on the secondary feed piston 660 may limit movement of the primary feed piston 650 in a direction away from the first end 700 of the feed cylinder 54a. Thereafter, the pressure of the fluid that is supplied via the second port 602 may be increased (e.g., to a pressure that is equal to the pressure of the fluid in the other ports) to cause the primary feed piston 650 to translate toward the first end of the feed cylinder 54a. 
When the second canister portion is opened, as when a new coil of collated fasteners are to be introduced to the drum, the pressure of the fluid that is supplied via the second and third ports 602 and 604 may be reduced (e.g., the second and third ports 602 and 604 may be vented to the atmosphere) by an amount that is sufficient to permit the pressure of the fluid that is provided by the first port 600 to urge the secondary feed piston 660 away from the first end 700 of the feed cylinder 54a. As the secondary feed piston 660 translates away from the first end 700 of the feed cylinder 54a (thereby positioning the projection 690 relatively further away from the first end 700 of the feed cylinder 54a), the primary feed piston 650 is translated relatively further away from the first end 700 of the feed cylinder 54a. The additional length in the stroke of the primary feed piston 650 that is obtained by shuttling the secondary feed piston 660 may be employed to improve the speed with which an initial one of the collated fasteners is loaded into the barrel and/or to render the process of loading collated fasteners into the nosepiece easier for an operator.
The example of FIG. 17 is somewhat similar to that which is illustrated in FIG. 16, except that the first vent channel 680b extends through the primary feed piston 650b into the second interior cavity 692b, the second vent channels 682b do not extend through the projection 690b but rather are disposed radially outward there from, and a seventh seal 710, which may be carried by the primary feed piston 650b, may be employed to form a seal between the primary feed piston 650b and the perimeter of the first interior cavity 656b that is formed in the secondary feed piston 660b. 
During operation, the first and second ports 600b and 602b may be vented in an appropriate manner (e.g., to the atmosphere) and pressurized fluid may be transmitted through the third port 604b to drive both the primary and secondary feed pistons 650b and 660b toward the first end 700b of the feed cylinder 54b. When a fastener is to be fed into the nosepiece, a fluid, which may have a pressure that is about equal to the pressure of the fluid that is supplied through the third port 604b, may be transmitted through the first port 600b to drive the primary feed piston 650b away from the first end 700b of the feed cylinder 54b to thereby index the feed pawl into engagement with a next one of the collated fasteners. Thereafter, the first port 600b may be vented to permit the fluid that is delivered through the third port 604b to shuttle the primary feed piston 650b toward the first end 700b of the feed cylinder 54b. When the second canister portion is opened, fluid under pressure may be provided through the first port 600b, while both the second and third ports 602b and 604b are vented to thereby cause both the primary and secondary feed pistons 650b and 660b to translate away from the first end 700b of the feed cylinder 54b. 
In the example of FIG. 18 is also similar to that which is illustrated in FIG. 16, except that the primary feed piston 650c lacks an internal cavity, the secondary feed piston 660c lacks a projection, and the fourth and sixth seals are omitted. During operation, fluid under pressure may be supplied through the first, second and third ports 600c, 602c and 604c, which drives both the primary feed cylinder 54c and the secondary feed piston 660c toward the first end 700c of the feed cylinder 54c. When a fastener is to be fed into the nosepiece, fluid pressure in the second port 602c may be vented in an appropriate manner (e.g., to the atmosphere), which permits the fluid that is delivered through the first port 600c to translate the primary feed piston 650c away from the first end 700c of the feed cylinder 54c to thereby index the feed pawl into engagement with a next one of the collated fasteners. Thereafter, the pressurized fluid may be communicated through the second port 602c to shuttle the primary feed piston 650c toward the first end 700c of the feed cylinder 54c. When the second canister portion is opened, both the second and third ports 602c and 604c may be vented while fluid under pressure is applied via the first port 600c to the primary and secondary feed pistons 650c and 660c to thereby cause both the primary and secondary feed pistons 650c and 660c to translate away from the first end 700c of the feed cylinder 54c. 
The embodiment of FIG. 19 is substantially similar to that which is illustrated in FIG. 18 and described in the immediately preceding paragraph, except that the primary and secondary feed pistons 650d and 660d are discrete pistons that are not sealingly engaged to one another.
The example of FIG. 20 also employs primary and secondary feed pistons 650e and 660e that are discrete and which do not sealingly engage one another. In this example, the first port 600e may be vented in an appropriate manner, while a pressurized fluid may be delivered via the second and third ports 602e and 604e. The application of fluid pressure to the second port 602e causes the primary feed piston 650e to be maintained in a position adjacent the first end 700e of the feed cylinder 54e, while the application of fluid pressure to the third port 604e causes the secondary feed piston 660e to be translated forwardly to a point where the end portion 676e contacts the feed cylinder 54e, When a fastener is to be fed into the nosepiece, fluid pressure may be applied to the primary feed piston 650e via the first port 600e, which causes the primary feed piston 650e to translate away from the first end 700e of the feed cylinder 54e and thereby index the feed pawl into engagement with a next one of the collated fasteners. Thereafter, the first port 600e may be vented so that the pressurized fluid that is introduced to the feed cylinder 54e via the second port 602e may translate the primary feed cylinder 54e to the position proximate the first end 700e of the feed cylinder 54e, When the second canister portion is opened, the third port 604e may be vented while fluid under pressure is applied via the first and second ports 600e and 602e to thereby cause both the primary and secondary feed pistons 650e and 660e to translate away from the first end 700e of the feed cylinder 54e. 
While the invention has been described in the specification and illustrated in the drawings with reference to various embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various embodiments is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise, above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the foregoing description and the appended claims.

## Claims

1. A fastening tool comprising:
a housing assembly having a nosepiece; and
a magazine assembly coupled to the housing assembly, the magazine assembly including a canister, a door structure, a feed pawl and a follower structure, the canister being configured to hold a plurality of collated fasteners and having a first canister portion and a second canister portion that is movable relative to the first canister portion between a closed position and an open position, the door structure carrying one of the feed pawl and the follower structure and being coupled to the nosepiece so as to be pivotally movable between a first position, which substantially clears the other one of the feed pawl and the follower structure, and a second position wherein the feed pawl and the follower structure may cooperate with one another to sequentially feed the collated fasteners into the nosepiece;
wherein a portion of the second canister portion overlies the door structure when the door structure is positioned in the first position and the second canister portion is positioned in the closed position; and
wherein the portion of the second canister portion clears the door structure when the door structure is positioned in the second position and the second canister portion is positioned in the open position.

2. The fastening tool of claim 1, wherein the second canister portion carries a latch member that engages a canister latch post when the second canister portion is positioned in the closed position to thereby maintain the second canister portion in the closed position and the door structure in the first position.

3. The fastening tool of claim 2, wherein the second canister portion includes an ear and a latch bracket, the ear including a pair of opposite end faces, the latch bracket abutting the opposite end faces.

4. The fastening tool of claim 1, wherein the nosepiece include a barrel having a longitudinally extending opening for receiving one of the fasteners there through and wherein a barrel portion is coupled to the door structure, the barrel portion shrouding a portion of the opening in the barrel when the door structure is positioned in the first position.

5. The fastening tool of claim 1, wherein the opening in the barrel of the nosepiece extends to a discharge end of the barrel.

6. The fastening tool of claim 1, wherein the magazine assembly further includes a double-acting cylinder for reciprocating the feed pawl relative to the nosepiece.

7. The fastening tool of claim 6, wherein the double-acting cylinder includes a feed cylinder, a feed piston, a plurality of first seals and a plurality of second seals, each of the first and second seals being coupled to one of the feed cylinder and the feed piston and sealingly engaging the other one of the feed cylinder and the feed piston, the first and second seals being axially spaced apart from one another.

8. The fastening tool of claim 6, wherein a first feed conduit couples in fluid connection a first end of the double-acting cylinder to the housing assembly and wherein a second feed conduit couples in fluid connection a second end of the double-acting cylinder to the housing assembly so that fluid power for reciprocating a piston of the double-acting cylinder is received from the housing assembly.

9. The fastening tool of claim 8, wherein the first and second feed conduits are coupled to the nosepiece.

10. The fastening tool of claim 9, wherein the nosepiece includes an upper flange and wherein one of the first and second feed conduits includes a channel that is formed into an upper side of the upper flange.

11. The fastening tool of claim 10, wherein the double-acting cylinder includes a feed cylinder structure that is formed with the nosepiece and the first and second feed conduits.

12. The fastening tool of claim 8, wherein the housing assembly includes a trigger valve, a main reservoir, a return reservoir and a variable sized reservoir, the variable sized reservoir being defined by a cylinder and a drive piston, the drive piston being employed to translate a driver for driving one of the fasteners into a workpiece, and wherein fluid power is provided from the housing assembly to the double-acting cylinder from one of the following: a) the main reservoir and the trigger valve; b) the variable sized reservoir and the main reservoir; c) the return reservoir and the main reservoir; and d) the return reservoir and the trigger valve.

13. The fastening tool of claim 1, wherein the door structure carries a detent pin and wherein contact between the detent pin and a magazine latch post resists movement of the door structure from the second position to the first position when the second canister portion is positioned in the open position.

14. The fastening tool of claim 13, wherein the door structure also carries a stop member that is configured to contact a complementary stop member when the door structure is positioned in the second position.

15. The fastening tool of claim 1, wherein a rotary motion is employed to move the second canister portion between the closed position and the open position.

16. The fastening tool of claim 15, wherein the second canister portion rotates in a first direction from the closed position to the open position and the door rotates in a second direction opposite the first direction from the second position to the first position.

17. A fastening tool comprising:
a housing assembly having a nosepiece; and
a magazine assembly coupled to the housing assembly, the magazine assembly including a canister, a door structure, a feed pawl and a follower structure, the canister being configured to hold a plurality of collated fasteners and having a first canister portion and a second canister portion that is movable relative to the first canister portion between a closed position and an open position, the door structure carrying one of the feed pawl and the follower structure and being coupled to the nosepiece so as to be pivotally movable between a first position, which substantially clears the other one of the feed pawl and the follower structure, and a second position wherein the feed pawl and the follower structure may cooperate with one another to sequentially feed the collated fasteners into the nosepiece;
wherein a portion of the second canister portion overlies the door structure when the door structure is positioned in the first position and the second canister portion is positioned in the closed position;
wherein the magazine assembly further includes a double-acting cylinder for reciprocating the feed pawl relative to the nosepiece;
wherein a first feed conduit couples in fluid connection a first end of the double-acting cylinder to the housing assembly and wherein a second feed conduit couples in fluid connection a second end of the double-acting cylinder to the housing assembly so that fluid power for reciprocating a feed piston of the double-acting cylinder is received from the housing assembly; and
wherein the housing assembly includes a trigger valve, a main reservoir, a return reservoir and a variable sized reservoir, the variable sized reservoir being defined by a cylinder and a drive piston, the drive piston being employed to translate a driver for driving one of the fasteners into a workpiece, and wherein fluid power is provided from the housing assembly to the double-acting cylinder from one of the following:
a) the main reservoir and the trigger valve; b) the variable sized reservoir and the main reservoir; c) the return reservoir and the main reservoir; and d) the return reservoir and the trigger valve.

18. A fastening tool comprising:
a housing assembly having a housing, a nosepiece and a motor, the housing defining a main reservoir and first and second feed channels, the nosepiece being coupled to the housing assembly, the motor including a cylinder that is housed in the housing and a piston that reciprocates within the cylinder between an extended position and a retracted position; and
a magazine assembly coupled to the housing assembly, the magazine assembly including a canister, a feed cylinder assembly, first and second feed conduits, a feed pawl and a follower pawl assembly with a door structure and a follower structure, the canister being configured to hold a plurality collated fasteners and having a first canister portion and a second canister portion that is hingedly coupled to the first canister portion, the second canister portion being movable between a closed position and an open position, the door structure carrying the follower structure and being coupled to the nosepiece so as to be pivotally movable between a first position, which substantially clears the other one of the feed pawl, and a second position, the feed cylinder assembly including a feed cylinder and a feed piston that is housed in the feed cylinder, the feed cylinder being mounted on the nosepiece and coupled in fluid connection to first and second feed conduits, the first feed channel coupling the first feed conduit to an interior of the cylinder, the second feed channel coupling the second feed conduit to the main reservoir, the feed pawl being coupled to the feed piston and reciprocating therewith;
wherein positioning of the door structure in the second position places the follower structure in a position where it inhibits movement of the collated fasteners in a direction away from the nosepiece when the feed pawl is translated in a direction away from the nosepiece;
wherein the door structure cannot be moved out of the first position unless the second canister portion is first moved out of the closed position;
wherein the door structure cannot be moved into the second position if the second canister portion is positioned in the closed position; and
wherein the door structure and the second canister portion are independently movable.

19. A fastening tool comprising:
a housing assembly having a nosepiece; and
a magazine assembly coupled to the housing assembly, the magazine assembly including a feed pawl and a feed cylinder assembly, the feed cylinder assembly including a feed piston assembly that is operable for translating the feed pawl relative to the nosepiece to sequentially feed collated fasteners into the nosepiece, the feed piston assembly including a primary feed piston and a secondary feed piston;
wherein the secondary feed piston is positionable in an extended position and a retracted position that is relatively further from the nosepiece than when the secondary feed piston is positioned in the extended position;
wherein the primary feed piston is translatable between a first position and a second position when the secondary feed piston is positioned in the extended position, and wherein the primary feed piston is translatable between the first position and a third position when the secondary feed piston is positioned in the retracted position, the third position being relatively further from the nosepiece than the second position; and
wherein one of the primary and secondary feed pistons is at least partially received into the other one of the primary and secondary feed pistons when the secondary feed piston is positioned in the extended position.

20. A fastening tool comprising:
a housing assembly having a nosepiece; and
a magazine assembly coupled to the housing assembly, the magazine assembly including a feed pawl and a feed cylinder assembly, the feed cylinder assembly including a feed piston assembly that is operable for translating the feed pawl relative to the nosepiece to sequentially feed collated fasteners into the nosepiece, the feed piston assembly including a primary feed piston and a secondary feed piston;
wherein the secondary feed piston is positionable in an extended position and a retracted position that is relatively further from the nosepiece than when the secondary feed piston is positioned in the extended position;
wherein the primary feed piston is translatable between a first position and a second position when the secondary feed piston is positioned in the extended position, and wherein the primary feed piston is translatable between the first position and a third position when the secondary feed piston is positioned in the retracted position, the third position being relatively further from the nosepiece than the second position; and
wherein placement of the primary feed piston in the second position is effected through contact between the primary and secondary feed pistons.

21. A fastening tool comprising:
a housing assembly having a nosepiece; and
a magazine assembly coupled to the housing assembly, the magazine assembly including a feed pawl and a feed cylinder assembly, the feed cylinder assembly including a feed piston assembly that is operable for translating the feed pawl relative to the nosepiece to sequentially feed collated fasteners into the nosepiece, the feed piston assembly including a primary feed piston and a secondary feed piston;
wherein the secondary feed piston is positionable in an extended position and a retracted position that is relatively further from the nosepiece than when the secondary feed piston is positioned in the extended position;
wherein the primary feed piston is translatable between a first position and a second position when the secondary feed piston is positioned in the extended position, and wherein the primary feed piston is translatable between the first position and a third position when the secondary feed piston is positioned in the retracted position, the third position being relatively further from the nosepiece than the second position; and
wherein placement of the primary feed piston in the third position is effected through contact between the primary and secondary feed pistons.

22. A fastening tool comprising:
a housing assembly having a nosepiece; and
a magazine assembly coupled to the housing assembly, the magazine assembly including a feed pawl and a feed cylinder assembly, the feed cylinder assembly including a feed piston assembly that is operable for translating the feed pawl relative to the nosepiece to sequentially feed collated fasteners into the nosepiece, the feed piston assembly including a primary feed piston and a secondary feed piston;
wherein the secondary feed piston is positionable in an extended position and a retracted position that is relatively further from the nosepiece than when the secondary feed piston is positioned in the extended position;
wherein the primary feed piston is translatable between a first position and a second position when the secondary feed piston is positioned in the extended position, and wherein the primary feed piston is translatable between the first position and a third position when the secondary feed piston is positioned in the retracted position, the third position being relatively further from the nosepiece than the second position; and
wherein the primary and secondary feed pistons cooperate with a feed cylinder to define three distinct cavities into which a pressurized fluid may be introduced to effect movement of the primary and secondary feed pistons.

23. A fastening tool comprising:
a housing assembly having a nosepiece; and
a magazine assembly coupled to the housing assembly, the magazine assembly including a feed pawl and a feed cylinder assembly, the feed cylinder assembly including a feed piston assembly that is operable for translating the feed pawl relative to the nosepiece to sequentially feed collated fasteners into the nosepiece, the feed piston assembly including a primary feed piston and a secondary feed piston;
wherein the secondary feed piston is positionable in an extended position and a retracted position that is relatively further from the nosepiece than when the secondary feed piston is positioned in the extended position;
wherein the primary feed piston is translatable between a first position and a second position when the secondary feed piston is positioned in the extended position, and wherein the primary feed piston is translatable between the first position and a third position when the secondary feed piston is positioned in the retracted position, the third position being relatively further from the nosepiece than the second position; and
wherein the magazine assembly further includes a canister that is configured to hold a plurality of the collated fasteners, the canister having a first canister portion and a second canister portion that is movable relative to the first canister portion between a closed position and an open position and wherein the secondary feed piston is translated from the retracted position to the extended position when the second canister portion is moved from the open position to the closed position.

24. The fastening tool of claim 23, wherein the secondary feed piston is maintained in the extended position when the second canister portion is in the closed position.

25. A fastening tool comprising:
a tool housing;
a drive motor housed in the tool housing;
a nosepiece coupled to at least one of the tool housing and the drive motor, the nosepiece including a barrel and a feed aperture that is formed in the barrel, the barrel defining a longitudinally extending aperture, the feed aperture comprising a longitudinally extending slot that is formed through the barrel, the longitudinally extending slot intersecting the longitudinally extending aperture and extending to an end of the barrel opposite the tool housing;
a magazine assembly coupled to at least one of the tool housing, the drive motor and the nosepiece, the magazine assembly being configured to house a plurality of fasteners and sequentially feed the fasteners through the feed aperture into the nosepiece; and
a nosepiece door pivotally coupled to one of the tool housing, the drive motor, the nosepiece and the magazine assembly and being movable between a closed position and an opened position, which substantially clears the feed aperture, the nosepiece door including a barrel portion that is received into the feed aperture proximate the end of the barrel opposite the tool housing when the nosepiece door is positioned in the closed position.

26. The fastening tool of claim 25, further comprising a contact trip that is movable relative to the nosepiece between a first position and a second position, wherein placement of the contact trip in the first position does not inhibit movement of the nosepiece door between the closed and opened positions, and wherein placement of the contact trip in the second position inhibits movement of the nosepiece door from the closed position to the opened position.

27. The fastening tool of claim 25, wherein the nosepiece door includes a barrel portion that closes at least a portion of the longitudinally extending slot proximate the end of the barrel opposite the tool housing when the nosepiece door is in the closed position.

28. The fastening tool of claim 25, wherein the nosepiece door substantially covers the longitudinally extending slot when the nosepiece door is in the closed position.

29. A fastening tool comprising:
a tool housing;
a drive motor housed in the tool housing;
a nosepiece coupled to at least one of the tool housing and the drive motor, the nosepiece including a barrel having a proximal end that is proximate the tool housing, a distal end opposite the proximal end and a central portion between the proximal and distal ends, the barrel defining an aperture, the aperture having a first portion that extends longitudinally through the proximal end and the distal end, the aperture also having a second portion that intersects the first portion and extends through an outer surface of the central portion, the second portion extending through the distal end;
a magazine assembly coupled to at least one of the tool housing, the drive motor and the nosepiece, the magazine assembly being configured to house a plurality of fasteners and sequentially feed the fasteners through the second portion of the aperture in the barrel into the first portion of the aperture in the barrel; and
a nosepiece door pivotally coupled to one of the tool housing, the drive motor, the nosepiece and the magazine assembly and being movable between a closed position and an opened position, which substantially clears the second portion of the aperture, the nosepiece door including a barrel portion that is received into the second portion of the aperture near or at the distal end of the barrel when the nosepiece door is positioned in the closed position.

30. The fastening tool of claim 29, further comprising a contact trip that is movable relative to the nosepiece between a first position and a second position, wherein placement of the contact trip in the first position does not inhibit movement of the nosepiece door between the closed and opened positions, and wherein placement of the contact trip in the second position inhibits movement of the nosepiece door from the closed position to the opened position.