Abstract:
A fastener driving device including a fastener depth adjusting assembly comprising a rotary adjusting member having an internal threaded section extending along an axis threadedly mounted on one of an upper and lower structures of a work contact assembly so that a rotational movement of the adjusting member with respect to the one structure effects a relative axial movement therebetween. Mounting structure is provided between another of the upper and lower structures and the adjusting member to mount the adjusting member on the another structure so as to be freely rotatable about the axis while being restrained against axial movement with respect thereto. The mounting structure positions the adjusting member so as to present an exterior surface in an accessible exterior position on a frame structure of the device. The exterior surface has a shape facilitating manual rotational movement of the adjusting member by a manual rolling action thereof. A yieldable holding member is mounted on the another structure for linear movement toward and away from the exterior surface of the adjusting member while being restrained against axial movement with respect thereto. The yieldable holding member is spring biased to continuously engage the exterior surface of the adjusting member. The yieldable holding member is constructed and arranged with respect to the exterior surface configuration of the adjusting member to continuously yieldably hold the adjusting member in a selected one of a series of rotational positions against free rotational movement in either direction while allowing manual rotational movements against the spring bias of the yieldable holding member in either direction with generally equal manual effort.

Description:
This application claims the benefit of U.S. Provisional application Ser. No. 60/147,403 filed Aug. 6, 1999. 
    
    
     This invention relates to fastener driving devices and, more particularly, to fastener driving devices of the portable type. 
     BACKGROUND OF THE INVENTION 
     The present invention is more particularly concerned with devices of this type which have a fastener penetrating depth adjusting assembly, such as disclosed in U.S. Pat. No. 4,767,043. The depth adjusting assembly disclosed therein interconnects upper and lower structures of the work contact assembly and is constructed and arranged to be manually adjusted to change the relative positions of said upper and lower structures between (1) a first position of adjustment wherein a work contact element at the lower end of the lower structure when the work contact assembly is in an operative position extends from a nosepiece structure a first extent and a fastener driven into a workpiece by the fastener driving element has a minimum workpiece penetration and (2) a second position of adjustment wherein the work contact element when the work contact assembly is in the operative position thereof extends from the nosepiece structure a second extent and a fastener driven into a workpiece by the fastener driving element has a maximum workpiece penetration. 
     The specific depth adjusting assembly disclosed in the &#39;043 patent includes a rotary adjusting member having a notched periphery cooperable with a spring locking arm so that when engaged with a notch in the periphery of the rotary adjusting member, the rotary adjusting member is securely held or locked against rotation. The spring locking arm is biased into locking relation in response to the pivotal movement of a guard member into an operative position shielding the rotary adjusting member against manual engagement. When the guard member is pivoted into an open position allowing convenient manual access to the rotary adjusting member, the locking arm is moved out of locking engagement with the rotary adjusting member allowing free manual movement thereof. The arrangement of the &#39;043 patent is quite effective in operation but the provision of the guide member adds cost to the assembly. 
     U.S. Pat. No. 5,685,473 discloses a depth adjusting assembly for accomplishing the same result. In the arrangement disclosed in the &#39;473 patent, the rotary adjusting member is free to rotate except when the work contact assembly is in fully engaged relation with the workpiece. The operation is achieved by providing a yieldingly releasable lock on the frame structure which moves into locking relation to the otherwise freely rotatable adjusting member when the work contact assembly is moved into engagement with the workpiece. The arrangement of the &#39;473 patent obviates the cost of the guard provided in the &#39;043 patent arrangement but leaves the rotary member free to inadvertent and accidental movement anytime the device is being handled. 
     U.S. Pat. No. 5,685,473 discloses a depth adjusting mechanism which includes a turnable member, however, the turnable member is constructed and arranged to be moved out of and into an indexing pin carried by the frame structure as the work contacting structure is moved into and out of contact with the workpiece. This arrangement enables the turnable member to be accidentally moved out of the desired adjustment position as the device is being portably moved around and handled. 
     Other patents, such as U.S. Pat. Nos. 5,385,286 and 5,564,614, illustrate depth adjusting assemblies in which springs are provided to yieldably maintain a rotary adjusting member in any desired position of adjustment. In general, these arrangements do not utilize the cost effective arrangement of the &#39;473 patent wherein the configuration of the exterior periphery is made to serve (1) to aid in manual movement and (2) cooperate with the spring bias. 
     BRIEF DESCRIPTION OF THE INVENTION 
     It is an object of the present invention to provide a depth adjusting assembly which achieves advantages of the cost effectiveness of the &#39;043 patent while eliminating the disadvantages thereof which allow for inadvertent free movement while the portable device is being handled. In accordance with the principles of the present invention, this objective is obtained by providing a fastener driving device comprising a frame structure presenting a handle portion constructed and arranged to be gripped by a user enabling the user to handle the device in portable fashion. Fixed nosepiece structure is mounted with respect to the frame structure defining a fastener drive track. A fastener driving element is slidably mounted in the drive track. A manually actuated fastener driving system is carried by the frame structure which is constructed and arranged to move the fastener driving element through successive operating cycles each including a drive stroke and a return stroke. A magazine assembly is carried by the frame structure which has fixed structure defining a fastener feed track leading to the drive track and movable structure constructed and arranged to enable a package of fasteners to be loaded in the magazine assembly and fed along the feed track so that the leading fastener of the fastener package is moved into the drive track to be driven outwardly thereof into a workpiece during the drive stroke of the fastener driving element. 
     An actuating member is constructed and arranged with respect to the frame structure to be moved rectilinearly in a direction generally parallel with the drive track between a normally biased inoperative position and an operative position. A trigger member is constructed and arranged with respect to the frame structure to be manually pivoted between an inoperative position and an operative limiting position thereabove. A work contact assembly is constructed and arranged with respect to the frame structure to be moved from a normally biased inoperative position into an operative position in response to the movement of the device into cooperating engagement with a workpiece. The work contact assembly includes an upper structure movable along a generally rectilinear path between an inoperative position corresponding with the inoperative position of the work contact assembly and an operative position thereabove corresponding to the operative position of the work contact assembly. The work contact assembly includes an upper structure and a lower structure separate from the upper structure and a fastener depth adjusting assembly interconnecting the upper and lower structures constructed and arranged to be manually adjusted to change the relative positions of the upper and lower structures between (1) a first position of adjustment wherein said lower structure portion when the work contact assembly is in the operative position thereof extends from the nosepiece structure a first extent and a fastener driven into a workpiece by the fastener driving element has a minimum workpiece penetration and (2) a second position of adjustment wherein the lower structure portion when the work contact assembly is in the operative position thereof extends from the nosepiece structure a second extent and a fastener driven into a workpiece by the fastener driving element has a maximum workpiece penetration. The fastener depth adjusting assembly comprises a rotary adjusting member having an internal threaded section extending along an axis threadedly mounted on one of the upper and lower structures so that a rotational movement of the adjusting member with respect to the one structure effects a relative axial movement therebetween, mounting structure between another of the upper and lower structures and the adjusting member constructed and arranged to mount the adjusting member on another structure so as to be freely rotatable about the axis while being restrained against axial movement with respect thereto. The mounting structure positions the adjusting member so as to present an exterior surface in an accessible exterior position on the frame structure. The exterior surface has a shape facilitating manual rotational movement of the adjusting member by a manual rolling action thereon. A yieldable holding member is mounted on the structure for linear movement toward and away from the exterior surface of the adjusting member while being restrained against axial movement with respect thereto. The yieldable holding member is spring biased to continuously engage the exterior surface of the adjusting member. The yieldable holding member is constructed and arranged with respect to the exterior surface configuration of the adjusting member to continuously yieldably hold the adjusting member in a selected one of a series of rotational positions against free rotational movement in either direction while allowing manual rotational movements against the spring bias of the yieldable holding member in either direction with generally equal manual effort. 
     Other objects of the present invention are to provide a device of the type describe above which is combined with other features hereafter described in detail. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a fastener driving device embodying the principles of the present invention with the parts in the normal inoperative position thereof; 
     FIG. 2 is a front elevational view of the device shown in FIG. 1; 
     FIG. 3 is a sectional view taken along the line  3 — 3  of FIG. 2; 
     FIG. 4 is an enlarged fragmentary sectional view taken along the line  4 — 4  of FIG. 2; 
     FIG. 5 is an enlarged fragmentary sectional view taken along the line  5 — 5  of FIG. 1; 
     FIG. 6 is an enlarged fragmentary sectional view taken along the line  6 — 6  of FIG. 1; 
     FIG. 7 is an enlarged fragmentary sectional view taken along the line  7 — 7  of FIG. 1; 
     FIG. 8 is an enlarged fragmentary sectional view taken along the line  8 — 8  of FIG. 2; 
     FIG. 9 is a fragmentary sectional view showing the trigger valve assembly with the trigger member, work contact assembly and enabling member in the normal inoperative positions thereof; 
     FIG. 10 is a view similar to FIG. 9 showing the position of the parts after the movement of the work contact assembly into the operative position thereof; 
     FIG. 11 is a view similar to FIG. 10 showing the position of the parts after the movement of the trigger member into the operative position thereof; 
     FIG. 12 is a view similar to FIG. 11 showing the position of the parts after the movement of the work contact assembly back into the inoperative position thereof; 
     FIG. 13 is a view similar to FIG. 12 showing the position of the parts after the movement of the work contact assembly into the operative position thereof with the trigger member having been first moved into the operative position thereof; 
     FIG. 14 is a view similar to FIG. 1 showing the magazine assembly in an intermediate joint clearing position; 
     FIG. 15 is an enlarged portion of the device shown indicated by the phantom circle  15 ; 
     FIG. 16 is an enlarged fragmentary sectional view taken along the line  16 — 16  of FIG. 14; 
     FIG. 17 is a fragmentary sectional view taken along the line  17 — 17  of FIG. 16; and 
     FIG. 18 is a view similar to FIG. 15 showing the magazine assembly in a separated condition. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now more particularly to the drawings, there is shown therein a fastener driving device, generally indicated at  10 , which embodies the principles of the present invention. While the device could be adapted to drive any type of fastener, as shown, the device  10  is particularly adapted to drive finishing nails which are supplied in the form of an angled stick package. 
     The fastener driving device  10  includes a housing or frame structure, generally indicated at  12 , which provides a handle portion  14  constructed and arranged to be gripped by a user enabling the user to handle the device  10  in portable fashion. The frame structure  12  also provides structure  16  extending generally perpendicular to the handle portion which constitutes a portion housing an air pressure cylinder  18  within the frame structure  12 . Slidably mounted within the cylinder  18  is a piston assembly  20  which divides the cylinder  18  into a drive chamber  22  on one side of the piston assembly  20  and a return chamber  24  on the opposite side thereof. A fastener driving element  26  is operatively connected with the piston assembly  20  and extends therefrom through a resilient bumper  28  in the bottom of the return chamber  24 . The lower end portion of the fastener driving element  26  is slidably mounted within a drive track  30  defined at its outer end by a nosepiece structure, generally indicated at  32 , which is operatively fixed with respect to the frame structure  12 . 
     The cylinder  18  and piston assembly  20  form a part of a manually actuated air pressure operated fastener driving system, generally indicated at  34 , which is carried by the frame structure  12  and is constructed and arranged to move the piston assembly  20  and fastener driving element  26  through successive operating cycles, each including a drive stroke and a return stroke. 
     The air pressure operated fastener driving system  34  also includes a reservoir  36  which is formed in the handle portion  14 , the construction of which is hollow. The reservoir  36  receives air under pressure from a source through a fitting (not shown) and communicates the supply of air under pressure therein to a space surrounding the upper end of the cylinder  18 . 
     The air pressure surrounding the upper end of the cylinder  18  is controlled by a pilot pressure actuated main valve assembly, generally indicated at  38 . Pilot pressure for operating the main valve assembly  38  comes from the reservoir  36  and is under the control of a manually actuated trigger valve assembly, generally indicated at  40 . A pivoted trigger member  42  is mounted on the housing structure  12  in a position below the handle portion  14  to be engaged by an index finger of the user. A contact trip assembly  44  is mounted so as to extend outwardly of the nosepiece  32  to be actuated when the device  10  is moved into operative engagement with a workpiece. An enabling assembly  46  acting between the trigger member  42  and the contact trip assembly  44 , with respect to the manually actuated trigger valve assembly  40  serves to enable the main valve assembly  38  to be manually actuated only when a sequential movement of first the contact trip assembly  44  and then the trigger member  42  is made in a manner hereinafter more specifically to be described. 
     The contact trip assembly  44  includes fastener depth adjusting mechanism, generally indicated at  48 , capable of being conveniently manually adjusted in a manner hereinafter more specifically explained to determine the countersink depth of the driven fasteners. 
     The air pressure driving system also includes a plenum chamber return system, generally indicated at  50 , for effecting movement of the piston assembly  20  through the return stroke thereof. The air displaced from the drive chamber  22  during the return stroke is discharged to atmosphere through an adjustable exhaust assembly, generally indicated at  52 , carried by the frame structure  12  in a position above the pilot pressure operated main valve assembly  38 . 
     A magazine assembly, generally indicated at  54 , is mounted on the frame structure  12  for movement from an operative position into a intermediate fastener jam removing position and therebeyond into a separated condition with respect to the frame structure  12 . A spring biased latch assembly, generally indicated at  56 , is operatively connected between the magazine assembly  54  and the frame structure  12  and is operable to resiliently bias the magazine assembly  54  into its operative position enabling a rearward nosepiece portion  58  carried by the magazine assembly  54  to yieldingly move away from a forward nosepiece portion  60  forming a fixed portion of the frame structure  12 . The spring biased latch assembly  56  when moved from the operative position thereof into an intermediate position is operable to resist the movement of the magazine assembly  54  out of its intermediate position. The spring biased latch assembly  56  is also movable from the intermediate position thereof into a separating position, enabling the magazine assembly  54  to be moved into a separated condition with respect to the frame structure  12 . 
     The pilot pressure actuated main valve assembly  38  may be of any known and suitable construction. However, as shown, it is constructed generally in accordance with the structural teachings of U.S. Pat. No. 5,207,143 and operates in the same fashion as the operation disclosed therein. For the details of the operation, reference may be had to the &#39;143 patent. For present purposes, it is sufficient to note that pilot pressure is normally allowed to communicate from the reservoir  36  to a pilot pressure chamber  62  which maintains a valve member  64  in closing relation to the upper end of the cylinder  18 . When the pilot pressure is relieved from the pilot pressure chamber  62 , the pressure surrounding the upper end of the cylinder  18  acts on the main valve member  64  to move it from its normally closed position with respect to the upper end of the cylinder  18  into a spaced position allowing the air under pressure surrounding the upper end of the cylinder  18  to enter therein and drive the piston assembly  20  with the fastener driving element  26  through a drive stroke. When pilot pressure is again established in the pilot pressure chamber  62  at the end of the drive stroke, the main valve member  64  is moved back into the closed position thereof, allowing a discharge opening  66  to communicate with the drive chamber  22  of the cylinder  18 . 
     The trigger valve assembly  40 , like the main valve assembly  38 , can be of any known or suitable construction. As shown, the trigger valve assembly  40  is generally constructed in accordance with the structural teachings disclosed in U.S. Pat. No. 5,083,694, and operated in the same way as described therein. For the details of the operation, reference may be had to the &#39;694 patent specification. For present purposes, it is sufficient to note that the trigger valve assembly  40  includes an actuating member  68  biased into a normal inoperative position by a spring  70 . In its inoperative position, as shown in FIGS. 3 and 9, the actuating member  68  conditions the trigger valve assembly  40  to communicate air pressure in the reservoir  36  with the pilot pressure chamber  62  of the main valve assembly  38  to thus retain the valve member  64  in cylinder closing relation. The movement of the actuating member  68  from the inoperative position thereof against the bias of spring  70  into the operative position thereof conditions the trigger valve assembly  40  to discontinue the communication of the reservoir air pressure with the pilot pressure chamber  62  and dump the air pressure in the pilot pressure chamber  62  to atmosphere. 
     As best shown in FIG. 9, the trigger member  42  is pivoted, as indicated at  72 , at a forward end thereof to the frame structure  12 . The enabling assembly  46  includes an enabling member  74  pivoted, as indicated at  76 , to a rearward end of the trigger member  42 . The enabling assembly  46  also include a compression coil spring  78  which is disposed in surrounding relation to a depending lower portion of the actuating member  68 . An upper end of the coil spring  78  is engaged with the lower surface of the handle portion  14  of the frame structure  12 . A lower end of the coil spring  78  engages the upper surface of the central portion of the enabling member  74 . The enabling member  74  has a forward end portion  80  which is disposed in cooperating relation with an upper end portion  82  of an upper structure  84  forming a part of the work contact assembly  44 . 
     The work contact assembly  44  also includes a lower structure  86  having a lower end portion disposed below the end of the nosepiece structure  32 . The lower structure  86  is made up of a metal rod bent into an inverted U-shaped configuration with the bight portion bent to seat within a work contact element  88 . 
     The fastener depth adjusting assembly  48  serves to interconnect the upper and lower structures  84  and  86  and is constructed and arranged to be manually adjusted to change the relative positions of the upper and lower structures  84  and  86  between (1) a first position of adjustment wherein when the work contact assembly  44  is in its operative position the work contact element  88  extends downwardly from the nosepiece structure  32  a first extent and a fastener driven into a workpiece by the fastener driving element  26  has a minimum workpiece penetration and (2) a second position of adjustment wherein when the work contact assembly  44  is in its operative position the work contact element  88  extends from the nosepiece structure  32  a second extent and a fastener driven into a workpiece by the fastener driving element  26  has a maximum workpiece penetration. 
     It will be understood that the need to adjust the depth that a fastener penetrates into the workpiece is particularly desirable when the fastener being driven is a finishing nail. Usually, the head of a finishing nail will be countersunk, although at times, it may be desirable to leave the head of the fastener above the workpiece surface. The depth adjusting assembly  48  has a range of adjustment that allows for a depth of penetration where the head is not only not countersunk but spaced above the workpiece surface as well. Where finishing nails are used as the fastener, as preferred here, countersinking is more important than with full headed nails, which are usually not driven beyond being flush with the workpiece surface. 
     As best shown in FIGS. 1-5, the lower structure  86  terminates at its lower end in a U-shaped portion  90  which includes a relatively thick bight section  92 . Disposed between the upper and lower legs of the U-shaped portion  90  is a rotary adjusting member  94 , constituting an essential part of the depth adjusting assembly  48 . The rotary adjusting member  94  is mounted between the U-shaped portion legs for free rotational movement about an axis generally parallel with the axis of the cylinder  18 . The legs of the U-shaped portion  90  mount the rotary adjusting member  94  against relative axial movement. The rotary movement is restricted to a single axis by exteriorly threading an upward extension  96  of one of the legs of the inverted U-shaped lower structure  86  and threadedly engaging the same within an interiorly threaded central axial section of the rotary adjusting member  94 . The rotary adjusting member  94  is thus mounted on the lower structure  86  so that a rotational movement thereof with respect to the lower structure  86  will result in a relative axial movement thereof with respect to lower structure  86 . 
     As best shown in FIG. 3, the upper end portion  82  of the upper structure  84  extends vertically and is mounted on the frame structure  12  in a lower rearward position on the cylinder housing portion  16  for vertical sliding movement. The upper end portion  82  of the upper structure  84  connects at its lower extremity with a laterally extending portion  98  and has a coil spring  100  surrounding the same with a lower end engaging the laterally extending portion  98  and an upper end engaged with the frame structure  12 . The coil spring  100  serves to resiliently bias the upper structure  84  downwardly into a limiting position corresponding with the inoperative position of the work contact assembly  44 . In this limiting position, the lower surface of the U-shaped portion  90  engages an upwardly facing stop surface  101  on the forward nosepiece portion  60 , as shown in FIG.  7 . 
     When the device  10  is moved into cooperating relation with a workpiece, both the lower structure  86  and upper structure  82 , which are held together by the fastener depth adjusting assembly  48 , are moved upwardly together into an operative position against the bias of spring  100 . 
     TRIGGER AND WORK CONTACT OPERATION 
     FIG. 9 illustrates the normal inoperative position of the actuating member  68 , trigger member  42 , enabling member  74  and the upper end portion  82  of the work contact assembly  44 . It will be noted that the end  80  of the enabling member  74  overlies the upper end portion  82  of the work contact assembly  44 . FIG. 10 illustrates the position of the parts after the user has moved the device  10  into cooperating relation with a workpiece. During this movement, the work contact member  88  engages the workpiece and effects an upward movement of the work contact assembly  44  from its normal inoperative position into an operative position. FIG. 10 shows that the upward movement of the end portion  82  of the work contact assembly  44  through a vertical path associated with this movement has moved the enabling member  74  so that its outer end  80  is moved through a first arcuate path. Since the enabling member pivot pin  76  remains stationary during this movement, the central portion of the enabling member  74  will engage the lower end of the actuating member  68  but will not move it appreciably as is shown in FIG.  10 . That is, the amount of upward movement of the actuating member  68  is insufficient to cycle the air pressure within the pilot pressure chamber  62  of the main valve assembly  38 . Consequently, in response to the movement of the work contact assembly  44  of the device  10  into contact with the workpiece surface, there will be no power actuation which takes place. 
     FIG. 11 illustrates the sequential movement of the trigger member  42  into an operative limiting position thereof after the nosepiece structure  32  has been moved into engagement with the workpiece. This trigger member movement, which is stopped by the engagement of the trigger member  42  with the adjacent frame structure  12 , will effect a movement of the enabling member  74  into its operative position. In this operative position, the central portion of the enabling member  74  has been moved upwardly a distance sufficient to move the actuating member  68  into the actuating or operative position thereof to thereby effect a cyclical movement of air within the pilot pressure chamber  62  and actuate the main valve assembly  38 . In this regard, it will be noted that the trigger member  42  is simply moved upwardly about its pivot  72  which carries with it the forward end of the enabling member  74  since the end  80  thereof is engaged with the extremity of the upper end portion  82  of the work contact assembly  44 . 
     FIG. 12 illustrates the position of the parts immediately following the normal rebound which occurs at actuation. The rebound serves to move the entire device  10  away from the workpiece, thus allowing the upper end portion  82  of the work contact assembly  44  to move downwardly as shown in FIG.  12 . FIG. 12 shows the work contact assembly  44  moved fully into the inoperative position thereof. It is evident from the drawing that the end of the enabling member  74  will move out of contact with the upper end of the work contact assembly  44  after a predetermined amount of movement which is less than the total amount of movement required to reach the inoperative position. 
     During this movement of the enabling member  74 , the end  80  of the enabling member  74  moves under the action of the spring  78  through a second arcuate path. At the end of the second arcuate path, the end of the enabling member  80  is disposed out of the vertical rectilinear path of the upper end portion  82  of the work contact assembly  44 . However, it will be noted that the amount of movement of the central portion of the enabling member  74  is sufficient to allow the actuating member  68  to be moved by the spring  70  from its operative position into its normal inoperative position. This cycles the air pressure within the pilot pressure chamber and signals the return stroke by the plenum chamber return system  50 . 
     FIG. 13 illustrates two other circumstances. First, FIG. 13 illustrates that, once the parts reach the position shown in FIG. 12, it is necessary for the trigger member  42  to be returned into its normal inoperative position with the device  10  disposed away from the workpiece in order to recondition the parts into the position shown in FIG. 9 so that another actuation can take place. If the user moves the device  10  back into contact with the workpiece immediately after recoil and then releases the trigger member  42  to allow it to move into its normal inoperative position under the urging of the spring  78 , the end  80  of the enabling member  74  will be moved into a third arcuate path during which it will engage the upper end portion  82  and prevent the trigger member  42  from returning into its normal inoperative position. The trigger member  42  will only return into its normal inoperative position after the device  10  is then moved away from the workpiece surface. 
     The other circumstance, illustrated by FIG. 13, is that, when the parts are in their inoperative positions as shown in FIG.  9  and the trigger member 
     FIG. 13 illustrates two other circumstances. First, FIG. 13 illustrates that, once the parts reach the position shown in FIG. 12, it is necessary for the trigger member  42  to be returned into its normal inoperative position with the device  10  disposed away from the workpiece in order to recondition the parts into the position shown in FIG. 9 so that another actuation can take place. If the user moves the device  10  back into contact with the workpiece immediately after recoil and then releases the trigger member  42  to allow it to move into its normal inoperative position under the urging of the spring  78 , the end  80  of the enabling member  74  will be moved into a third arcuate path during which it will engage the upper end portion  82  and prevent the trigger member  42  from returning into its normal inoperative position. The trigger member  42  will only return into its normal inoperative position after the device  10  is then moved away from the workpiece surface. 
     The other circumstance, illustrated by FIG. 13, is that, when the parts are in their inoperative positions as shown in FIG.  9  and the trigger member  42  is moved into its operative position before the device  10  is moved into cooperating relation with the workpiece, the movement of the trigger member  42  will effect a movement of the end  80  of the enabling member  74  through a fourth path in which the end  80  ends up in the same position as when moved through the second arcuate path as shown in FIG.  12 . This movement of the enabling member  74  with the trigger member  42 , as shown in FIG. 13, is insufficient to effect a movement of the actuating member  68  out of its normal inoperative position and, hence, no actuation will occur. If, after the trigger member  42  has been moved into the position shown in FIG. 13, the user moves the device  10  into cooperating relation with the workpiece, the upper end portion  82  of the work contact assembly  44  will be moved upwardly through its vertical rectilinear path but, since the end  80  of the enabling member  74  is not in this path of movement, there will be no actuation. 
     The fastener depth adjusting assembly  48  interconnects the lower structure  86  with the upper structure  82  in a manner which enables the vertical position of the work contact element  88  to be adjusted between a maximum position below the lower end of the nosepiece structure  32  corresponding with maximum fastener workpiece penetration and a minimum position therebelow corresponding with a minimum fastener workpiece penetration. 
     As best shown in FIG. 7, the maximum position is determined by the bent end of the short leg portion of the inverted U-shaped lower structure  86  engaging stop surface  103  on the forward nosepiece portion  60 . This interengagement also prevents the lower structure  86  from being adjusted to a position that allows it to fall off. The minimum position is determined by the end of the threaded leg portion  96  engaging a stop cap  105  carried by the U-shaped portion  90 . 
     As best shown in FIG. 5, the exterior peripheral surface of the rotary adjusting member  94  is formed with a series of axially extending recesses  102  spaced apart by a series of axially extending ridges  104 . This configuration renders the total exterior surface  102 - 104  of the rotary adjusting member  94  particularly suited to be manually rotated by a manual rolling action. 
     To render the manual movement of the rotary adjusting member  94  more convenient to the user, the U-shaped portion  90  is mounted at one side of the nosepiece structure  32  midway between the lower end of the cylinder housing portion  16  of the frame structure  12  and the work contact element  88 . In order to keep the rotary adjusting  94  from being easily rotated in its convenient position by unwanted or accidental engagements, the fastener depth adjusting assembly  48  includes a yieldable holding member  106 . 
     As best shown in FIG. 5, the holding member  106  is mounted within a cylindrical bore  108  in the bight section  92 . An outer end portion  110  of the holding member  106  is shaped to engage within an aligned rotary member recess  102  while also engaging the ridges  104  which separate the aligned recess  102  from the recesses  102  adjacent thereto. The holding member  106  is hollow rearwardly of the outer end portion  110  so as to house a coil spring  112  therein. One end of the coil spring  112  engages the bight section  92  while the other engages the end portion  110  of the holding member  106 . The spring  112  thus resiliently biases the outer end portion  110  of the holding member  106  outwardly into engagement with the aligned rotary member recess  102  and adjacent ridges  104  and enables the holding member  106  to yieldingly move against the action of the spring  112  when the rotary adjusting member  94  is deliberately manually moved to a new adjusted position. Depending upon the direction of rotational movement manually imparted to the rotary adjusting member  94 , one or the other of the adjacent ridges  104  will slidably engage the end portion  110  of the holding member  106  to effect the movement of the latter against the action of the spring  112 . As the engaged ridge  104  continues to slide by the outer end portion  110 , spring  112  will bias the holding member  106  into engagement with the adjacent recess  102 . In this way, the depth of penetration of the fasteners into the workpiece is adjusted to any desirable position within the range of adjustment between maximum and minimum provided. 
     The plenum chamber return system  50  is of conventional nature and includes check valved openings  114  extending through the cylinder  18  into a surrounding plenum chamber  116  formed between the exterior of the cylinder  18  and the interior of the cylinder housing portion  16 . As the piston assembly  20  moves toward the end of its drive stroke, the check valved openings  114  are uncovered and the air under pressure in the drive chamber  22  driving the piston assembly  20  is allowed to enter into the plenum chamber  116 . The lower end of the plenum chamber  116  is communicated by an opening  118  through the cylinder into the return chamber  24  at the level of the bumper. 
     The bumper  28  is engaged by the lower surface of the piston assembly  20  at the end of the drive stroke and is arrested thereby. As soon as the pressure in the drive chamber  22  is relieved by the movement of the main valve assembly  38 , the air pressure within the drive chamber  22  is communicated with the outlet opening  66  provided by the main valve assembly  38  communicating the air pressure within the drive chamber  22  with the adjustable exhaust assembly  52 . As soon as the air pressure is relieved, the air pressure which is contained in the plenum chamber  116  acts on the lower end of the piston assembly  20  so as to effect a return stroke thereof. The air within the drive chamber  22  displaced by the movement of the piston assembly  20  through its return stroke is discharged through the outlet opening  66  into the adjustable exhaust assembly  52  and, from there, into the atmosphere. 
     The adjustable exhaust assembly  52  includes an adjustable exhaust air direction member  120  having a radially extending exhaust outlet  122 . The adjusting member is freely rotated on the top of a removable cap member  124  fixed to the upper end of the cylinder housing portion  16  of the frame structure  12  as by bolts  126 . As best shown in FIG. 8, the cap member  124  at its upper end portion defines a radially extending outer terminal of the exhaust opening  66  which leads to an external annular recess  128  in the cap member  124 . 
     The exhaust air directing member  120  surrounds the recess  128  and is freely rotatably mounted on the upper end of the cap member  124  by mounting structure in the form of a C-clip  130  engaged within an annular groove  132  in the upper extremity of the cap member  124 . In operation, the C-clip  130  overlies the upper surface of the exhaust air directing member  120  with the lower surface thereof extending in an upwardly facing annular groove  134  in the cap member  124 . 
     Annular resilient sealing structure, in the form of upper and lower O-ring seals  136  and  138  respectively are constructed and arranged (1) to ensure that air displaced into said exhaust opening  66  is discharged into the atmosphere through the radially outwardly extending exhaust outlet  122  in a direction determined by the rotational position of the exhaust air directing member and (2) to yieldingly retain exhaust air directing member in any rotational position into which it is manually moved. 
     The upper O-ring seal  136  is disposed within an O-ring seal groove  140  formed in the exterior periphery of the cap member  124  and engages an annular surface in an inturned upper edge of the exhaust air directing member  120 . The lower O-ring seal  138  is disposed within an annular notch  142  formed in a lower corner of an inturned lower edge of the exhaust air directing member  120  and engages in the inner corner of the groove  134 . As shown, the lower O-ring seal  138  is compressed somewhat to provide for the resilient yielding movement of the exhaust air directing member  120  although upper O-ring seal also plays a part. 
     The magazine assembly  54  may also embody any well known or suitable construction. As previously indicated, the magazine assembly  54  is particularly adapted to receive and handle angled stick packages of finishing nails. As such, the magazine assembly  54  includes a magazine frame structure  144  which provides fixed structure defining a fastener feed track  146  for supporting an angled stick package of finishing nails along their angularly arrayed heads and for guiding the leading nail of the package into the drive track  30 . 
     The magazine frame structure  144  leaves the rearward end of the drive track  146  open in order to enable the user to load new fastener stick packages therein. A one way clutch structure  148  is disposed in cooperating relation to the feed track  146  at its rearward end and is constructed and arranged to allow fastener stick packages to be moved forward thereby but to prevent subsequent rearward movement thereof (unless manually released). The one way clutch structure  148  cooperates with a one way pusher assembly  150  which is capable of moving with a resilient yielding action rearwardly past a fastener stick package held against rearward movement by the one way clutch structure  148 . Once the one way pusher assembly  150  is moved beyond the rearwardmost fastener of the fastener stick package, the pusher of the pusher assembly  150  is biased to moved into the center of the drive track to engage the rearwardmost fastener and feed the package along the feed track  146 . 
     As best shown in FIG. 3, the pusher assembly  150  effects the feeding movement by a negator spring  152  carried by the upper forward portion of the magazine frame structure  144  and connected with the pusher assembly  150 . 
     As previously stated, the magazine assembly  54  is movable with respect to the frame structure  12  of the device  10 . To this end, the magazine frame structure  144  provides a forward female guide structure  154  at its upper forward end which cooperates with a male guide structure  156  extending upwardly and rearwardly from the upper rearward portion of the nosepiece structure  32  as is best shown in FIGS. 14 and 18. 
     Mounted on the magazine frame structure  144  in rearwardly spaced relation from the forward guide structure  154  is a rearward guide structure  158  of generally T-shaped cross-sectional configuration. Formed on the lower rearward edge of the handle portion  14  is a depending frame section  160  on which is mounted an inverted U-shaped plate member  162 . The rearward end of the depending frame section  160  is recessed and the rearward end of the bight portion of the invented U-shaped plate member is slotted to guidingly receive the rearward guide structure  158  on the magazine frame structure  144 . 
     As best shown in FIG. 17, the forward end of the depending frame section  160  has a forwardly opening bore  164  therein within which a compression coil spring  166  is disposed. The inner end of the coil spring  166  seats within the end of the bore  164  and the outer end seats within the outer wall of a hollow locking member  168  which is slidably mounted within the bore  164 . The outer wall of the hollow locking member  168  includes a lower protruding element  170 . 
     The locking member  168  and spring  166  form a part of the spring biased latch assembly  56  which also includes an L-shaped latch member  172 . A forward end of the latch member  172  is pivoted to the magazine frame structure  144  forwardly of the rearward guide structure  158 , as by a pivot pin  174  extending between a spaced pair of upstanding latch receiving elements  176  on the magazine frame structure  144 . The latch receiving elements  176  include short arcuate or kidney shaped openings  178  which slidably receive the ends of the pivot pin  174  therein. 
     As best shown in FIG. 1, the latch member  172  at a position rearwardly of the pivot pin  174  includes laterally extending portions defining forwardly locking surfaces  180  which are positioned to engage rearwardly facing lower projecting surfaces  182  on the upstanding elements  176  when the latch member  172  is in the normal operating position thereof, as shown in FIG.  1 . Also, as shown in FIG. 17, when the latch member  172  is in the normal operating position thereof, an upwardly facing catch surface  184  on the forward end of the latch member  172  engages beneath the protruding locking element  170 . In the normal operating position of the latch member  172 , the spring  166  also presses the hollow locking member  168  against the end of a push button  186  mounted for limited reciprocating movement within the forward end of the latch member  172  above the catch surface  184 . 
     It is important to note that, when the latch member  172  is in the normal operating position thereof, the spring  166  acts against the hollow locking member  168  which biases it forwardly and the engagement of the hollow locking member  168  in turn presses on the latch member  172  in such a way as to tend to pivot it about the pivot pin  174  but this pivotal movement is prevented by the engagement of catch surface  184  with the protruding locking element  170 . Thus, the entire forward thrust imparted to the latch member  172  is transmitted directly to the magazine frame structure  144  through interengaging surfaces  180  and  182 . 
     In this way, the magazine assembly  54  is resiliently biased into the normal operating position thereof, shown in FIGS. 1 and 3, wherein the rearward nosepiece portion  58  thereof engages the forward nosepiece  60  fixed to the frame structure  12 . This forward biasing of the rearward nosepiece portion  58  enables a fastener improperly driven within the drive track  30  to yieldingly move the rearward nosepiece portion  58  rearwardly away from the forward nosepiece portion  60  to thereby alleviate a situation which otherwise might create a jam. In the event, that a fastener jam does occur, access to the drive track  30  can be obtained for purposes of clearing the jam by moving the latch member  172  from the normal operating position thereof into the intermediate jam clearing position thereof. 
     To this end, the latch member  172  includes an angled handle portion  188  extending from the free end thereof which can be engaged in the hand of a user while the user&#39;s finger pushes on the push button  186  in a rearward direction. The rearward movement of the push button  186  moves the hollow locking member  168  rearwardly against the bias of spring  166  thus disengaging the protruding locking element  170  from the catch surface  184  allowing the user to simultaneously move the handle portion  188  forward to allow the forwardly facing latch surfaces  180  to disengage from the lower projecting surfaces  182 . As soon as the rearwardly moved push button  186  and the latch member  172  move out of the path of forwardly biased movement of the hollow locking member  168 , the hollow locking member  168  will move forwardly to a limiting position. 
     The magazine frame structure  144  can be moved rearwardly with respect to the frame structure  12  to an intermediate jam clearing position, as shown in FIG.  14 . In this position, the latch member  172  will have been moved into an intermediate position, as shown in FIG. 14, wherein the latch surfaces  184  engage upper projecting surfaces  190  on the upstanding elements  176  to resist further pivotal movement of the latch member  172 . In this intermediate jam clearing position of the latch member  172 , further rearward movement of the magazine frame structure  144  from the position shown in FIG. 14 will engage the latch member  172  against the spring biased hollow locking member  168 . In this way, when the latch member  172  is in its intermediate jam clearing position, a resistance to further movement of the magazine assembly  54  beyond the intermediate jam clearing position shown in FIG. 17 is provided by the spring biased latch assembly  56 . 
     As best shown in FIG. 18, when the latch member  172  is in its intermediate position, it is possible for the user to manually engage the angled handle portion  188  of the latch member  172  and move it forwardly. During this movement, the engagement of the latch surfaces  180  with the upper projecting surfaces  190  causes the ends of the pivot pin  174  to ride up within the pivot pin openings  178 . When the latch member  172  reaches the separating position shown in FIG. 18, the magazine assembly  54  can be separated from the frame structure  12  as shown in FIG.  18 . 
     It is recognized that, since the device is portable, it will not always be oriented in a manner to fit the directional words used herein which are accurate when the device is being operated on a horizontal upwardly facing surface. 
     Any U.S. patents or patent applications mentioned or cited hereinabove are hereby incorporated by reference into the present application. 
     It will thus be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodiments have been shown and described for the purpose of illustrating the functional and structural principles of this invention and are subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.