Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2 ~ 7
SAFETY INTERLOCK SYSTEM FOR FASTENER DRIVING TOOL
CROSS REFERENCE TO R~LATED APPLICATION
This application is a continuation-in-part
application of United States patent application Serial
No. 07/523,704 filed on May 15, 1990 and is as~igned to
the same assignee as the assignee of this application.
BACKGROUND OF THE_INVBNTION ..
the Inventio~ -.
The~present invention relates generally to a
sa~ety mechanism for a fastener driving tool and more
paxticularly, to a new and improved~safety mechanism
~ that insures that the ~astener driving tool will be
; actuated in~response to the actuation of a manually- ~;
operated trigger only after a sc~fety member of the
fastener drivlng tool has been properly positioned
15 against a workpiece. ~;
2- ~ b~Y~ b~n~
Portable astenex driving tools are used
. .
extensively in light manufacturing sectors. In its
normal mode o~ operation, a ~astener driving tool is
20 actuated by air pressure so that a fastener, such as a
nail, staple or the like, is ejected from a nosepiece of
the ~astener driving tool into a workpiece during a
driving stroke of the tool. The exceedingly high air
pre~sures used (on the order o~ 100 pounds per square u
25 inch) results in the fastener being ejected from the
tool with a great amount o~ Porce and at a high
velocity.
' ".
2 ~ 9 7
-2-
Due to the force with which the fastener is
ejected from the fastener driving tool, improper opera-
tion of such a fastener driving tool can be hazardous.
A number of different safety mechanisms have been
devised ~or such fastener driving tools in an attempt to
eliminate accidental or inadvertent firing or actuation
of the tool and injuries caused by the improper use of
the tools. However, it has been found that those safety
mechanisms do not insure that the ~astener driving tool
will not be used in an improper ~ashion, especially i~
th~ safety mechanisms are compromised.
A number of safety mechanisms for such
fastener driving tools include a workpiece contact
engaging member which, if not depressed against the
workpiece prior to the trigger of the fastener driving
tool being depressed, prevents the fastener driving tool
from being fired or actuated~ on the other hand, some
safety mechanisms for fasten~r driving tool~ permit the
operator of the tool to continue driving fasteners with ~:
successive bump~ of the workpiece contact engaging mem-
ber by simply maintaining the trigger depressed. How-
ever, operation of the fastener driving tool in this
manner may be dangerous. - ,
Safety mechanisms for fastener driving tools .:
are disclosed in United States Patent No. 3,784,077
issued on ~anuary 8, 1974 and in United States Patent ~ .
No. 4,260,092 issued on April 7, 1981. The safety mech~
anis~s disclosed in those patents tend to prevent the
disclo~ed ~astener driving tool from being act~ated to
drive a ~astener if a workpiece engaging portion associ~
ated with the nosepiece of the ~astener driving tool is : .
not first depressed against a workpiece or if the work-
piece engaging portion is not maintained depressed
ayainst the workpiece. However, the trigger in these
35 d~vices may be pivoted or depressed without the work- .
piece engaging portion being depressed, thereby creating
the possibility of accidental Piring, particularly i~
''''~ ' .,:
~ 20~2~97 ~
the safety mechanism is compromised through wear or mis-
handling.
United States ~atent Nos. 3,464,614 and ::
3,519,186 also disclose safety mechanisms for a fastener
driving tool. The safety mechanism disclosed in each of
~hose patents includes a blocking lever that will pre-
vent the trigger of the fastener driving tocl from being
depressed to actuate a driving stroke to drive a fas- :
tener unless a workpiece engaging portion is properly
maintained against a workpiece. However, the trigger
may be moved somewhat prior to the workpiece engaging
por*ion being positioned against a workpiece. Moreover,
the fastener driving tool is not permitted to return to
its standby condition unless the trigger is released
completely.
Some existing tools allow for c~ntinued actua- :
tion of the tool even though the workpiece engaging
portion of the nosepiece partially returns toward its
inoperative position, as for example, when the tool
recoils after being actuated. This creates the possi-
bility that a fastener inadvertently will be driven,
perhaps on top of a previously d~eiven f~stener. ~:
Consequently, a need exists for a safety mech- ::
anism that prevents the trigger :Erom bPing depressed to
actuate a ~riviny stroke of a fastener driving tool when
th~ safety mechanism is not prop~rly placed against a
workpiece, locks the safety mechanism into a non~
actuating mode when the trigger is even partially `
depressed prior to the safety member being positioned
against a workpiece, but permits the resetting o~ the
~astener driving tool even if the safety member moveæ
slightly away from the workpiece, as for example, during
recoil of the fastener driving tool.
SUMMAI~ a_____ENTION :
Accordingly, it is an object of the present
~nvention to provide a safety mechanism for a fastener
2 ~ 9 7
--4~
driving tool which overcomes de~iciencies in existing
safety mechani ms for fastener driving tools.
Another object o~ ~he present invention is to
provide a safety mechanism for a ~astener driving tool
that only allows the trigger to be ~ully depressed to
actuate a driving stroke of the fastener driving tool
when a safety member is fully engaged with a workpiece.
Still another object of the present invention
i~ to provide a safety mechanis~ for a fastener driving
tool that prevents the tool from operating if a safety
member is not first engaged with a workpiece. This is
accompli~hed by a trigger lock-out mechanism whereby the
trigger cannot be depressed ts initiate a ~astener
driving stroke unless the tool is first engaged against
a workpi~ce. An advantage of thi~ feature is the
requirement imposed on the operator to first engage the
safety member against the workpiece before depressing
the trigger to eject a fastener.
A further object of the present invention is
to provide a safety mechanism ~or a fastener driving
tool that actually locks a safety member in an inopera~
tive po ition when the trigger of the fastener driving
tool is depressed before the safety member is engaged
against a workpiece. ~: :
Yet another object of the present invention is
to prevent a fastener driving tool from being actuated - ~.
after ejection of a fastener if the safety member is not
fully depressed against the workpiece, but nevertheless ~-
permits the fastener driviny tool to be reset for actua- -
30 tion of another driving stroke even if the safety member ~. .
i8 not completely depres~ed against the workpiece. This
is accomplished by allowing the trigger to xeturn to a ~ :
transition position even if the tool raises slightly .~ :
~rom the-workpiece due to recoil but prohibits the trig- .
35 yer from again being depressed to actuate another driv- ::
iny ~troke until after the safety member again is fully :
engaged with the workpiece. : .
.
~2~97
,~
-5-
In a~cordance with these and many otherobjects o the present invention, a fastener driving
tool e~bodying the present invention includes a power
mechanism operable during a fastener driving stroke to
drive a fastener from a nosepiece of the tool into a
workpiece. The fastener driving stroke is initiated by
an operator depressing a manually operable trigger that
is movable between a rest or inoperative position and a
firing or operative positionO A workpiece engageable
safety member is movably affixed on the nosepiece and is
movable be~ween a standby or inoperative positlon and an
actuated or operative position.
A afety mechanism for the fastener driving
tool includes an interlock mechanism associated with
both the trigger and the safety member. The interlock
mechanism assures that (1) the trigger will not be :
depressed from its standby position to it~ actuated
position unless the safety member is moved to its fully
actuated or operative position by pressing the sa f ety
member against a workpiece; (2) the safety member will
be locked into its standby posit:ion as long as the trig- :
ger is being depressed toward it:s actuated position
prior to the sa~ty member bein5~ depressed against the
workpiece; (3) the trigger will be permitted to return
toward its standby position everl though the safety mem-
ber i~ not fully engaged against the workpiece such that ;
the fastener driving tool will be reset and ready for
the initiation o~ another driving stroke as soon as the
safety member again is fully d~pressed against the work- :
piece; (4) the trigger is permitted to return from its
firing position to its full rest position only when the
sa~ety member is in its full actuating position; and (5)
the safe~y member will be prevented from returning rom
its actuated position to its standby position while the
trigger is still in its firing position. In order to
~ccomplish these safety interlock functions, the trigger
has a trigger interlock portion including a trigger rod
, -.
, . ' ~ '. . ,;: . , ~,, :'
',, ' ', '' ' ,,' ' ~', ,, . '.' ' , , ' : . ,
' ' ' . ' ' ' . ,~ ' '' ~' ' '.
" ,". " : "' ', ; . `
9 7
.
~6-
and the safety member has a sa~ety member interlock por-
tion including a series of three relie~s. The trigger
rod interacts with the safety member interlock portion
and may b2come lodged in a particular one o~ the reliefs
depending on the relative positions of the trigger and
the sa~ety member.
BRIEF DESCRIPTION OF ~E DRAWINGS
Many other object~ and advantages oP the pre-
~ent invention will become apparent from considering the
~ollowing detailed description o~ the embodiment of ths
invention illustrated in the drawings, wherein:
FIG. 1 is a partially cut away side view of a
portiQn of a fastener driving tool having a safety mech-
anism em~)odying the present invention with the safety :
I5 member being fully extended to its standby, inoperative
: position and the trigger being in its rest or inopera- .
tive position such that the ~ast~ner driving tool is in ~ .
a static mode: :
FIG. 2 is a partially cut-away front view of :-
20 FIGo 1 taken along line 2-2 o~ FIG. 1;
FIG. 3 is a side view similar to FIG. 1 with
the safety member being fully depressed to its actuated :.
position and the trigger 5 . ill in its inoperative posi~
tion; :~:
FIG. 4 is a side view similar to FIG. 1 with
the safety member being f~lly depressed to its actuated ;~:
po~ition and the trigger also being ~ully depressed so
that a driving stroke o~ the fastener driving tool is
lnitlated; .
FIG. 5 is a side view similar to FIG. 1 with
the ~afety member being displaced slightly from its
~ully depressed, actuated position and the trigger being : -
moved slightly away ~rom its ~ully depressed position .;
a~ter a driving stroke of the ~astener driving ~QOl has
been completed;
FIG. 6 is a side view similar to FIG. 1 with
the safety member being partially depressed toward its
2~2~7
actuated pnsition and the trigger having been returnPd
to a transition position so that the fastener driving
tool i~ reset to a ~tatic mode;
FIG. 7 is a side v~ew similar to FIG. 1 with
the safety member being locked in its ~ully extended,
inoperative position due to the ~act that the trigger
has b~en depressed somewhat from in its rest or inopera-
tive positlon prior to the engagement of the sa~ety
~ember against a workpiece: and
FIG. 8 i~ enlarged view of a portion of the
fastenPr driving tool shown in FIG. 5 and in particular
the ball valve used in the fa~tener driving toel and the
mechanism by which the ball ~alve is actuated. -
DETAXT~ED DESCRIPTION O~ THE PREFERRED EMBODIMEyT
Re~erring now ~ore specifically to FIG. 1 of ::.
the drawings, therein i~ disclosed a fastener driving
tool 10 having a trigger and safety mechanism generally
designated by the re~erence numeral 12 and embodying the
pre ent invention. The fastener driving tool 10 may be :
one of several diPferent types of tools known in the
art. One such tool i disclosed in United States Patent
No. 3,fi83,746, the assignee of which is the assignee of
record of the present application. The disclosure of . :
U.S. Patent No. 3,~683,746 is incorporated by reference
herein. The fastener driving tool 10 is operable to
drive ~asteners [not ~hown) into a workpiece (also not ::
shown) by ejecting fasteners from a nosepiece or nose
: ~portion 14 of the fa~tener driving tool 10 when the
nos2piece 14 is placed against the workpiece. ~ -
In order for a fastener to be driven into the .
workpiece by the fastener driving tool 10, a driving
stroke is initiated by depressing a trigger 16 so that
the trigger 16 moves from an inoperative or rest posi-
tion a~ illustrated in FIGS. 1 2 to an operative or
~iring position illustrated in FIG. 4. A manually
operable safety membe.r 18 ~orming a portion of the
trigger and safety mechanism 12 i8 movably mounted on
"
.,, , ,, ",, ~ . ... . . . . . .
,, ,......... ,,;.:", . . .
- .
~ 2~2~7
-8-
the nosepiece 14 of the fastener driving tool 10. The
safety member 18 moves from an inoperative or standby
position as illustrated in FIGS. 1-2 to an operative or
actuating position as illustrated in FIGS. 3-4 when a
workpiece engaging portion 20 of the safety member 18 is
pushed and properly maintained against a workpiece.
Portions of the trigger 16 and the safety
me~ber 18 for~ an safety interlock ~echanism generally
referred to in the drawing~ by the reference numeral 22.
The sa~ety interlock mechanism 22 insures that (1~ the
trlgger 16 will not be depressed Prom its standby
po~ition to its actuated position unles the safety
member 18 is moved to its fully actuated or operative ~:
position by pressing the safety member 18 against a
15 workpiece; (2) ~he safety member 18 will be locked into ~-
it~ standby positio~ as long as the trigger 16 is being ~-.
depressed toward its actua~ed position prior to the :~
sa~ety member 18 being depressed against the workpiece;
(3) the trig~er 16 will be permitted to return toward
its standby position even though the safety member 18 is
: not fully engaged against the workpiece such that the -:
fastener driving tool 10 may be reset and ready for the
initiation of another driving stroke as soon as the
~afety member 18 again is fully depressed against the : -
25 workpiece; (~) the trigger 16 is permitted to return ~ -
Prom its ~iring position to its full rest position only
when the safety member 18 is in its full actuating posi~
tion; and (5) the safety member 18 will be prevented
from returning from its actuating position to its
standby position while the trigger 16 is still in its
~iring position.
As a result, the safety interlock mechanism 22
provides the fastPner driving tool 10 with various
safety or interlock functions. In this regard, the
trigger 16 cannot be depressed to actuate a driving
stroke of the fastener driving tool 10 unless ~he safety
member 18 is placed in its full, actuating position as
, .,, , ,, ~ !, ...... , ' , . , , . , ~
- 2 ~ 9 7
g
illustrated in FIG. 3 of the drawings by depressing the
workpiece engaging portion 20 against the workpiece into
which a ~astener is to be drivenO Moreover, the safety
member 18 is per~itted to move from it~ actuating posi-
tion to its standby position only when the trigg~r 16 isat its rest position. If the trigger 16 is depressed
prior to the safety member 18 being moved towards its
operative position illustrated in FIG. 3, the safety
interlock mechanis~ 22 lock~ the safety member 18 in its -
inoperative position until the trigger 16 is ~ully
released Ssee PI~. 71. Another interlock mode is pro- . :
vided to prevent the recycling o~ the fastener driving
tool 10 unless the safety ~ember 18 is in its fully
actuated position. In this interlock mode, the trigger
15 16 is prevented ~rom returning to its ~irin~ position :
unless the safety member 18 is at it~ ~ully actuated ~:
positio~.
As previously indicated, a driving stroke of
the ~astener driving tool 10 is initiated by the manual
20 depression of the trigger 16 by an operator. The trig- -
ger 16 includes a trigger actuat:ing portion 24 extending
from a pivotable portion 26. The pivotable portion 26
is pivotally mounted to the fast:ener driving tool 10 by
a pin or rod 28. When a ~inger of an operator depresses
or actuates the trigger actuating portion 24 and if the
~a~ety member 1~ i~ in its fully actuated or operative .
position shown in FIG. 3, the trigger 16 is permitted to
rotat~ about th~ pin 28 in a generally counterclockwise
dir~ction as the trigger 16 is viewed in FIGS. 1 and 3
of the drawings. As the trigger 16 is so rotated, pins
30 and 31 associated with a trigger valve 32 are dis-
placed as shown in FIG. 4 and a driving stroke of the
~astaner driving tool 10 is initiated. More specifi-
cally and as also is shown in FIG. 8 of the drawings,
the pin 30 extends between an upper surface 34 of the
trigger actuating portion 24 and a spring 36 that is
dispo~ed about the pin 31. The pin 30 is hollow so that
-: ' ' - ' ' , ' .:' ' ' i: ' ~ ' .,
,' , , ,, . . ~: : '. . . .
~ 2~2~7
--10--
the lower end of the pin 31 can extend into the pin 30.
A biasing spring 38 normally maintains the trigger 16 in ::
its inoperative position. As the trigger 16 is pivoted -~
about the pin 28 against the force o~ the biasing spring
5 38, the pin 30 will mova up as it i viewed in the : -
drawing~ and as described in more detail below, th~ pin - :
31 also will be moved upward. As a result, the trigger
valve 32 i5 closed and ~s will be described hereinafter
a driving stroke oP th~ ~astener driving tool 10 is ~ ~
10 ini iated. :;:. .
A trigger interlock portion 39 ~orms the oppo-
site end of the trigger 16 from the trigger actuating
por~ion 24. The trigger interlock portion 39 also :-
pivot~ about the pin 2~ and includes a trigger rsd or ~.
15 pin 40 that has its longitudinal axis generally perpen- :;
dicular to the longitudinal axis o~ the trigger 16. As
will be descri~ed hereinafter, the trigger rod 40 inter- ~
acts with a safety member interlock portion 42 o~ the : ~ :
safety memher 18 so as to pro~ide ~he fastener driving ~ :
20 tool 10 with the various differe:nt safety:modes or ~ : :
features describ~d above.
~he safety me~ber 18 is slidably mounted about
the no3epiece 14 o~ the fastener driving tool 10. It is
biased to i~s standby or inoperative position illus-
25 trated in FIGS. 1-2 and 7 by a biasing spring 44 that is
mounted be~ween a lower surface 46 on a front end 48 of .
the ~astener driving tool 10 and a flange 50 extending
rrOm a depending region 52 o~ th~ safety member ~8. The
safety member 18 is generally S-shaped and include~ the
depending region or linking portion 52 which extends
between the workpi~ce engaging portion 20 and an inter~
mediate portio~ 54 that extends to the safety member
interlock portion 42. The safety member interloc~ por-
tion 42 is ~ecured to the intermediate portion 54 and
35 includes a projecting member 56 and three relie~s or ~;
recesse~ 58, 60, and 62 on a side 64 of ths safety
.
' . '.. ' . ~ ' . ' ' ' ~' ~ ' '
-11- 20~2~97
member interlock portion 42 facing or adjacent to the
trigger rod 40.
As previously indicated, the ~astener driving
tool 10 i8 in its standby or static mode when the safety
member 18 is in its inopsrative position and the trigger
16 i5 likewise in it~ inoperative position. Thi~ static
mode of the factener driving tool 10 is illustrated in .
FXG. l-2 of the drawing~. When the ~asten r dri~ing
tool lO i~ in thi3 static mode, th~ trigger valve 32 is
open such that a trigger valve ball 65 i~ held against
an O-ring seal 66 due to the high air pre~sure being
supplied through an inlet line 68 and notwithst~nding
the upper force being applied by the biasing spring 36.
As long a~ the trigger valve ball 65 is maintained
15 against the O-ring seal 66, the line 68 is maintained in ~
communication with an air line 70 and the driving blade
o~ the fastener driving tool 10 is maintained in its
static, non-driving condition.
As is ~een in FIG. 1, the trigger rod 40 is ~.
disposed adja~ent the projecting member 56 as long as
the safety member 18 is maintainled in it~ inoperative
position. I~ any attempt is mad~e to depress the trigger : ;
16 while the safety member 18 is in its inoperative
position illustrated in FI~. l, the trigger rod 40 will
become lodg~d in the upper r~lie~ 58 formed just above
the projecting me~ber 56 (see; for example, FIG. 7 of
the drawings). When the trigger rod 40 becomes so
lodged in th~ relief 58, the trigger 16 cannot be
depressed any further so that the trigger valve 32 will
remain open. A~ a result, a driving stroke of the ~as-
t~ner driving tool 10 cannot be initiated. Moreover,
with the trigger rod 40 lodged in the relief 58, the
saPety member 18 becomes locked in its inoperative posi-
tion shown in FIG. 7 so that even i~ the workpiece
eng~ging portion 20 o~ the afety member 18 is pressed
again~t a workplece, the safety member l~ cannot be
moved to its operative position as long as the trigger
, . , . ~, ~ : , , : .
" " , , - , . . .
.. .. .
. .
,: . . .. . . .
, , . ; .: ~ , ,
.
2 ~ 7 ~ :
-12--
16 i~ being manually depressed. This insures that the
safety features of the fastener driving tool 10 will not
be overcome by an op~rator partially depressing the
trigger 16 prior to the engage~ent of the safety member
5 18 against a workpiece. -:
In order for a driving ~troke of the fastener
driviny tool 10 to be initiated, the workpiece engaging
portion 20 o~ the safety member 18 ~ust be forced ~.
against a workpiece such that the sa~ety ~e~ber 18 will :-
move relative to the nosepiece 14 o~ the ~astener driv~
inq tool 10 against the force of the spring ~4 to its
operativ~ position shown in FIG. 3 of the drawings.
When the sa~ety member 18 is in its operative position,
the lower relief 62 i~ exposed or becomes accessible to
15 the trigger rod 40. As a result, an operator of the :
~astener driving tool la may depress the trigger actuat-
ing portion 24 of the trigger 16 upwardly as the trigger
member 16 is viewed in FIG. 4 o the drawinys. As the
trigger 1~ is so dapressed, the trigger rod 40 pivots in
20 an arcuate path such that the trigger rod 40 becomes .;~
: lodged in the lower relief 62 of the safety member
interlock portion 42. At the same time, the upward ~::
movement o~ the upper surface 34 o~ the trigger actuat- :
ing portion 24 results in the displacement of the pin 30
upwardly such that the spring 36 associated with the
trigger valv~ 32 is compressed. Once the force being ~
: ex~rted on the pin 31 through the spring 36 exceeds the :-
amount of pressure exerted on the ball valve 65 by the . .-:
air pressure in the air inlet 68, the trigger valve ball
65 will move away ~rom the trigger valve 0-ring seal 66
and into a position sealing of~ the air inlet 68. With
the air line 70 now in communication with an air exhaust ,~
port 72 and with the air inlet 68 so sealed, the air in
the line 70 is exhausted to atmosphere through the air
exhaust port 72 such that a driving stroke of the fas-
tener driving tool 10 is initiated. A ~astener then i8
' ,
~2~7
13- :
driven into a workpiece on which the workpiece engaging
portion 20 is lodgedO
As long as the trigger 16 remains in its ~ully
operativ~ position illustrated in FIG. 4 o~ the draw-
ings, the trigger valve 32 remains closed preventing areturn stroke of the fastener driving tool 10 such that
another driving stroke o~ the fastener driving tool 10
cannot be initiated. on the other hand~ the trigger 16
may be released by the operator so a~ to be in the po i-
tion disclosed in FIG. 3 i~ the saPety member 18 remainsin its fully actuated posi ion illustrated in FIG. 3 of
the drawings. Another driving stroke then can be initi-
ated by the operator again depressing the trigger 16. ..
~owever, the recoil and shock that is exerted
against the fastPner driving tool lO as a result of the
driving of a fastener into a workpi ce h~s a tendency to :~
rai~e the fastener driving tool lO away ~rom the work-
piece such that the sa~ety member 18 moves slightly away
~rom its fully operative po ition. In addition, the
operator tends to slightly relax his grip on the trigger
member 16 due to this recoil. As a result, the fastener :
driving tool 10 i~ placed in a transition mode that is
illustrated in FIGS. 5 and 8 of the drawings wherein the
trigger membsr 16 i~ shown as having been moved slightly
away from it fully actuated position and the safety
membar 18 iS shown as having likewise moved slightly ;
away from its fully operative position. In this transi-
tion mode, the trigger rod 40 is positioned somewhere
between the lower relief 62 and the middle or transitory
relie~ 60. Even though the trigger 16 has moved
slightly away ~rom it~ fully actuated or operative posi-
tion, the force exerted by the springs 36 on the pin 31
is su~icient to maintain the trigger valve ball 65
against the air inlet 68 notwithstanding the air pres-
sura being applied against the ball valve 65 ~rom theair inlet 68. Consequently, the fa tener driving tool
10 i8 not returned to its static mode so that a return
, ~ . . . .
. . .. .
, , . ,
,, ; . : : - '.: ,~ ~:
';,,~ ' ' . ' ''"'' ' .
~ ~ ",. .
:
,
~ 2 ~ ~ 2 ~ 9 7
ol4-- . .
~troke of the fastaner driving tool 10 cannot be accom-
plished and another driving stroke will not be
initiated.
As the fastener driving tool 10 moves further
away ~rom the workpiece, the spring 44 associated with
the sa~ety member 18 moveis the ~aPety member 18 ~urther
away Prom its fully operative position (see, for
example) FIG. 6 of the drawings). When the safety mem- . :
ber 18 movas to thi~ position, the trigger ~od 40 is
expo~ed to the relie~ 60 and the trigger 16 can be moved
by the spring 38 towards its fully inoperative position.
Even thou~h the trigger rod 40 is disposed in the relief
60, the trigger 16 is preventad from returning to its ~ .
~ully inoperative positionO Nevertheless, the movement : .
of the trigger 16 to the transition position illustrated
in FIG. 6 is su~Picient to relax the ~orce being applied
to the trigger valve ball 65 by the biasing spring 36.
In response to this diminished force, the air pressure
in the air inlet 68 is sufficient to move the trigger
valve ball 65 against the 0-ring seal 66 and the trigger ~:
valve 32 again is opened. With the trigger valve 32 so
open, the pneumatic circuit between the air inlet 68 and :
the air line 70 i8 reestablished so that a return stroke
o~ the fa tener driving tool 10 is initiated and the ~
25 fastener driving tool 10 again is set in its static . - ;
mode. I~ the trigger 16 were prevented ~rom moving away
fro~ it~ ~iring position as long as the saPety member 18
i8 not returnea to its fully inoperative position, a ;
~ast~ner may be inadvertently ejected from the fastener
30 driving tool 10 if the high air pressure source is ~
disconnected from the fastener driving tool 10 and later `
reconnected. This inadvertent driving of a fastener
will not occur as long as the trigger 16 is allowed to
return to the transition position illustrated in FIG. 6
o~ the drawings such that the ~astener driving tool 10
i8 reset to it static mode even though the safety member ~.
. , ~ .
9 7
-15-
~8 ha~ not been returned to it~ full inoperative
pa~ition.
However, th~ repo3itioning of the trigg~r 16
in the transition positlon illustrated in FIG. 6 of the
drawing~ doe~ not p~rmit another driving stroke to be
initiated a~ long as the safety m~b~r 18 is in thi~
transitiv~ position because as long a3 the trigger rod
40 i~ di~po~ed in the middle reli~ 60, the trigger rod
40 i~ blocked by th~ æa~ety member interlock portion 42 - . .:
and th~ trigger 16 cannot b~ depre~.ed again to initiate
anothçr driving stroke o~ the fastener driving ~ool 10. ~ .
It i~ only when th~ safety me~ber 18 again is returned ~:
to it~ ~ully operative po~ition as, for example, illus-
trate~ in FIG. 3 of the drawings, that the triggex rod
40 is exposed to the lower relie~ area 62 and the trig-
ger 1~ can be depressQd for ini~iation o~ another driv~
ing stroke.
Many modifications a~d variations of the
present invention are possible in li~ht of the above
teachingsO Thus, it is to be understood that, within
the scope o~ th~ appended claim~, the invention may be
practiced oth-r th~n a~ speci~ically dcs~ribed above.
~ '
. .
..
~. . .
. ~ . , .
