NOV- 26, 1946- O ‘E. WQSTEVENS . 2,411,561 7 ’ BUCKING BAR CONTROL FOR RIVE'I'ING HAMMERS 7 ‘Filed Feb. 4, 1944 ’ v 2 Sheets-Sheet l INVENTOR fan/mm /1./ JTEVi/VJ. BYv _ - ATTORNEY v ’ Nov. 26, 1946. E. w. STEVENS _ 2,411,561 BUCKING BAR CONTROL‘ FOR RIVETING HAMMERS Filed Feb. 4, 1944 2 Sheets-Sheet 2 E R. gQ hm 13.? NM w% .. m“. mmum “x .15 E- -m._a"1-5: , @E ATTO R N EY Patented Nov. 26, 1946 2,411,561 UNITED STATES PATENT OFFICE} I 2,411,561 BUCKING BAR CONTROL FOR RIVETING HAMMERS Edward W. Stevens, Detroit, Mich, assignor to Chicago Pneumatic Tool Company, New York, N. Y., a corporation of New Jersey Application February 4, 1944, Serial No. 521,028 11 Claims. ' This invention relates to riveting apparatus assemblies fundamentally comprising a ?uid ac tuated tool and a bucking bar cooperating there with to set rivets, and more particularly to cer tain features of automatic bucking bar remote control mechanism for said tool. An object of the present invention is to intro duce an improvement related to the copending application Serial No. 467,531 of James A. Rob- erts, ?led December 1, 1942 for Bucking ‘bar con trol for riveting hammers, which has matured into Patent No. 2,375,691, granted May 8, 1945. The invention has a special but by no means ex clusive application to aircraft riveting tools suita ble for operation on light sheet metal. . (or. 78-48) 2 Fig. 4 is also an enlarged elevation of the bucking bar mechanism similar to that of Fig. 2 but showing the manual control lever‘in oper ated position and in released or neutralized con dition ; Fig. 5 is a transverse section of the mechanism of Fig. 4 as taken on line 5—-5; . Fig. ‘6 is another transverse section of the same taken on line 6-6 in Fig. 4; and Fig. 7 is a fragmentary perspective view of the manual operating lever of the same mechanism. In the riveting art- the use of riveting assem blies of the present kind requires the services of two operators on opposite sides of the work who are occasionally hidden from each other, ren The main object of this invention is therefore dering each operator incapable of noting directly to facilitate riveting by providing a bucking bar the movements of the other. In some assemblies mechanism for a ?uid actuated riveting hammer used'before the invention of Roberts in the co or other tool having direct manual control, with pending application, the throttle valve for the improved means governing the height of the 20 ?uid supply was arranged to be under the con heads of the rivets to be set and operating auto trol of a single operator, either the riveter or the matically to stop the hammer when the prede bucker, who would usually delay commencement termined height of a rivet has been produced. Another very important object is to increase of the hammering operation until certain that the other operator was ready. Occasionally it then happened that the hammer was started be fore the rivet was properly backed up or before the hammer was inproper operative position, which in either case would likely result in dam the, speed and uniformity of the‘ riveting opera tion by providing adjustable accurate control of the hammer from the bucking bar mechanism in such manner as to produce uniformly set rivets with substantial elimination of» damaged work. aged Work. It is also an object to have‘associated with a pneumatic hammer, a bucking bar mechanism or assembly provided with a member which not only governs the height of the heads of rivets to be set, but positively prevents production of ‘ ‘ satisfactory and rapid work, the present inven- I . tion is directed to improved means for positively determining a uniform height of the heads of the Other objects and the advantages inherent ‘in the invention and accruing'from its use in ac- ' tual practice will appear more fully in detail as this speci?cation proceeds. r ' ' involved is not onlyaffected by the speed of opera tion as ensured by effective cooperation between the two operators, but also by the uniformity in the height and-quality of the heads on the ?n ished rivets." If some. rivets are at ?rst not sum ciently set during operation, necessitating re Fig. l is a side elevation of a ?uid actuated hammer in operative position against a Work 7 , number of rivets are to- be set, the time element ' The invention is illustrated in the accompany ing drawings forming part hereof and in ‘which: operating position; rivets intended to be set. It is, of course, self-evident that when a large ' piece with a bucking bar mechanism operatively connected to the hammer and embodying c‘bn trol means for determining the height of the rivet heads intended to be set by the mentioned ap paratus, portions of the apparatus being shown in section to disclose details of construction while the manual control lever is illustrated in active _ engaged in ‘the work to see each other or to ob serve any special precautions-in order. to produce too ?at or small rivet heads even when the buck ing bar is held adjacent to the work for an un usually long time. I l While the invention of said Roberts is designed to eliminate the mentioned disadvantages and facilitate the operation of setting a rivet to such an extent that ‘it is unnecessary for the‘operators peated operation to bring them to uniform height 50 with the rest, time is lost, and if set too much, they are defective and damage has resulted. The present invention is designed to ensure that at all times the heads of the rivets will be set to a uniform height. - Fig. 2 is an enlarged side elevation, for the Hence, referring again to the drawings, a riv most part in section, showing the bucking gbar 55 eting assembly comprises a pneumatic hammer, mechanism with the manual control lever in ini tial starting position ready to initiate a cycle of operation; ‘ ‘ generally indicated at 8 of a type favored in the aircraft industry for setting small aluminumand' alloy rivets, The hammer assembly includes a Fig. 3*is an end view of the same device as ' cylinder 9 with an offset rigid handle iii and‘ 60 houses a ?uid operated motor provided with a seen from the right in Fig. 2; 2,411,561 3 'reciprocable piston H and means for directing pressure fluid alternately to the ends thereof, while the handle is formed with an air inlet port l2 and throttle means operating under the control of a trigger is. The piston ll acts as a hammer, delivering impacts to an anvil or rivet set M which extends beyond the front end of the cylinder for engagement with the work. The work or work piece, in this instance, is repre 4 unseats valve 24, whereupon air from inlet port l2 and passage 20 is allowed to ?ow through bushing 23 and into passage 2| whence it flows to the motor to initiate operation of the hammer. Air under pressure is supplied to the inlet port 12 through a ?tting in the form of an aux iliary valve housing 30 introduced between the inlet port l2 and a hose line 3| to facilitate control of the operation of the hammer by means sented by a pair of overlapping plates generally 10 of the invention. The auxiliary housing 39 has indicated at l5 (hereinafter termed “the work”) which are fastened together by rivets to form part of an airplane skin covering. Guide holes are ?rst provided in the work to receive rivets IS, the same being disposed with preformed 15 heads contacting with the work l5 on one side thereof and having shank portions projecting a tubular portion 32 extending into the inlet port I2 in threaded connection with a bushing 33. The body of thesame housing 30 de?nes a cham— ,‘ber 34 receiving air from the hose line 31 and communicating with the interior of tubular por tion 32 by way of a passage 35. Controlling the flow of air from chamber 34 to passage 35 is an auxiliary throttle valve 36, which has a valve through to the opposite side. According to one head 31 disposed within chamber 34 while the method of riveting, anvil or rivet set I4 is pressed against the preformed head on the rivet While 20 valve stem 38 thereof extends through passage 35 and into a split projection 39 on the housing. the shank portion is engaged on the opposite The head 31 of valve 36 is adapted to occupy or side of the work and during operation set as engage with avalve seat 49 on the peripheral shown at I‘! by a bucking bar it of a bucking edge of passage 35 and thereby cut off the flow of mechanism generally indicated at l9. When the fluid from chamber 34 to tubular portion 32 and 25 hammer is then started, percussive impulses are inlet port l2. rl‘he supply of air to the hammer delivered to the work through the anvil l4 and is therefore under the dual control of the throt are sustained by the bucking bar it‘. As forward tle valve 24 and the auxiliary valve 36, either pressure is exerted by the bucking bar through or both of which when closed will cut off the out the operation the reaction of the hammer blows serves to upset the shank of the rivet, a 30 supply of fluid from the motor and so prevent operation of the hammer. The two valves 24 ?at or oval head being thereby formed on the and 36 are actually arranged in series and thus side of the work opposite to that occupied by the preformed head. It is important that the skin surface of the provide the dual control of the operation. The opening of valve 35 is accomplished by re work be not marred or scratched by a premature 35 mote control from the bucking bar l8 by means of a Bowden type ?exible cable 4! extending be hammer action. Thus care must be exercised tween the hammer 8 and the bucking mechanism by the separate operators holding the hammer 19 and made up of a wound sheath 42 and an and the bucking mechanism that the ends of the inner wire or core 43 slidable within said sheath. rivet are initially properly engaged before the The cable at one end is received in the split hammer is started. As a matter of precaution, projection 39 of housing 30 and at its other end the apparatus is designed to guard against mis extends through a similar split clamping pro operation resulting from a lack of such engage jection 44 on the bucking bar ?tting in a trans ment by placing the compressed air supply under verse bore 45 in said bar. Clamping screws 46 the control of both the riveter and the bucker. ‘and 41 in the respective split projections 33 and The piston I I can therefore not begin reciproca 44 serve to clamp the ends of the cable within tion until the operators of the hammer and the two implements. The core 43 is movable bucking bar mechanism signify by releasing the air supply that their respective implements are in effective working position. Important as the features just mentioned may be for proper opera tion, it should be noted that it is a prominent feature of the invention to make it wholly un necessary for the bucker to observe any special care in order to produce a uniform height of rivet head on all rivets set when using the pres ent bucking bar mechanism. The air inlet port I2 is part of a pressure ?uid supply pasageway including passages 29 and 2l communicating through a bore 22. Within said bore 22 is a bushing 23 having ports registering respectively with passages 29 and 2 I . Communi cation between passages 29 and 2| is controlled by a trigger operated throttle valve 24 in bushing 23, said valve being pressed by a spring 25 to a seat 26 between the ported areas of the bushing and so normally prevents the flow of fluid to the passage 2! and thereby to the hammer cylinder. Valve 24 has a stem 2‘! extending upward through and beyond the bushing ,23, the upper end of the stem underlying one arm of a lever 28 which is pivotally mounted at 29 within a re cess in the handle it and is operatively engaged with the trigger l3. When the trigger is shifted rearward by the pressure of the ?nger of an operator the lever 23, rocking upon its pivot 29 ‘longitudinally within its sheath and arranged with one end projecting beyond the sheath, where it is secured to the stem 38 of valve 36 by soldering, brazing or Welding. The other end of the same core projects upwardly in a counter bore 48 in the bucking bar and is capped by a plunger 49 secured thereto and located in said counterbore and normally projecting a short dis tance above the bucking bar. The counterbore 48 is of greater diameter than the bore 45 re ceiving the end of the cable sheath and forms a casing for a compression spring 5i surround ing the cable core beneath plunger 49 and tend ing to hold the latter resiliently in the raised initial position shown in Figs. 1 to 3 and causing a pull to be exerted on said cable core, thereby maintaining the auxiliary throttle valve in hous ing 39 normally closed. The means included in the bucking bar mecha nism‘or assembly for depressing the plunger and thereby opening the auxiliary throttle valve to allow pressure ?uid to enter inlet port l2 from chamber 34 primarily consists of a manual oper ating lever 52 preferably formed of sheet metal of inverted U-shaped cross section with the sides 53, 53 bent down from the top web portion 54 and terminating in a pair of lugs 55 at the forward 75 end thereof, pivotally mounted in a pair of op 2,411,561 posite side recesses 56 on a pivot pin 51 in the bucking bar l8. Within the sides 53, 53 of lever 52 is a movable escape or release slide member 58. This latter is made of a metal strip bent back on itself to form upper and lower slide strips 59, SI connected at oneend by a web portion 62 and shiftably mounted upon a pair of cross rods 63 in such fashion as to straddle the latter, the slide member 58 being slidable longitudinally within . ‘6 latter, a set screw '81 in said post serving to fix the adjustable screw 85 in any attained position of adjustment. Thus, ‘when the'bucker is about to bring the bucking bar against the rivet ‘It, the ?rst portion 7 of the bucking mechanism which will make con tactvwith the work as already explained is the end of the sleeve 14, and although the latter projects - a distance beyond the working end 75 of the sides 53 and top 54 of said manual lever. To the 10 bucking bar, it is obviously quite simple for the » rear or ‘outer end Ell of the manual lever 52 is bucker to locate said end of the bar on the rivet ?xed an interior guide rod ‘65 extending longi without loss of time .or exercise ‘of vgreat ‘care. tudinally forward in substantial parallelism with When the device is moved toward the work I5 the-‘top and sides toward the pivoted end of the suf?ciently to bring end 15 of bucking bar I8 into manual lever and projecting slidably into the 15 actual contact with the rivet as shown in Fig. 1, rear end or web 62 of the‘ release slide member the sleeve 14 will be pushed in upon the bucking through an aperture 66 and supporting a coil bar against the resistance of spring ‘l1, and when the operator of said device depresses the manual lever52 from the position of Figs. 1 to 3 to that of latter forward. Upon the underside of the lever 20 Figs. 4 and 5, the contact of the lower strip 6| of is ?xed an inflexible plate 68 serving to assist in release slide member 58 within or beneath the retaining the release slide member in place and manual lever with the plunger or cap 49 will cause more de?nitely to press upon the upper end of a the latter to be depressed, and this in turn imme lever return plunger 69 located in a limited bore diately opens the auxiliary valve 36 in casing 30 ‘H in the bucking bar and provided with a com of the hammer. spring '6'! bearing against the rear end of, said releaseslide member and thus tending to urge the The trigger operated throttle pression spring 12 tending to raise said plunger 25 valve 24 having already been opened by the riv against said lever plate and thereby raise the eter, as, already stated, the opening of valve 316 lever to normal starting position in which the just mentioned immediately allows pressure ?uid plunger cap 49 upon the cable core 43 is also in to ?ow to the piston ll of the hammer, and start normal raised position with the auxiliary throt ' ' I 30 actual operation of the latter. tle valve 36 closed. During this operation, as the riveting rapidly In the lower strip H of the release slide mem proceeds, the sleeve is gradually pushed further ber is an aperture or gap 13 which is adapted to in upon the bucking bar by the latter following register with the upper end of the cable cap as in up the progressive shortening of the rivet until a manner now to be explained. When the riveter 35 the rivet has been completely set as shown at IT or hammer operator has placed the hammer 8 in in Fig. 4. Such rearward movement 'of the sleeve operative position against the head of a rivet it and then manually presses the trigger or plunger 13 and thereby opens the throttle valve 24, the hammer will not begin to operate until certain 40 other conditions are also present. . - is continuously transmitted to the release slide member 58 within lever 52 in opposition to spring 6’! of the. latter and produces a corresponding rearward travel of said member 58 until the aper ture “E3 in the bottom of the same begins to regis ter‘with the cable plunger 49. At this instant the When the bucker who handles the bucking mechanism is about to cooperate with the riveter mentioned plunger, urged by its spring'5l, im to set a rivet, he places the end of the bucking bar mediately rises up into the aperture 13 directly l8 more or less accurately against the shank end 4-5 above the same and by correspondingly pulling of rivet l6. ‘During this movement a sleeve 14 on the‘ cable core 43, effects instant closure of adapted to surround the rivet ?rst engages auxiliary valve 36 in the hammer assembly and against the work l5 and is resiliently retracted stops operation of the hammer. The time of sub upon the bucking bar by pressure until the lat sequent closure of the throttle valve 24 by release ter makes contact with rivet it in‘ a manner and 50 of the'trigger l3 by the rivet is of minor impor for a purpose now to be explained. The men- ' tance in the cycle of operation just described, and tioned sleeve is slidably mounted on the forward the two devices are therefore shifted by both op working end 15 of the bucking bar and has an erators to a new rivet for setting the same in a expanded rear portion ‘i6 surroundinga'spring' new cycle of operation. 7 Tl engaging forwardly at one end against a The hammering operation is thus terminated. shoulder 18 in said sleeve and rearwardly against automatically when the front end 15 of the buck a shoulder 79 on said bucking bar at the other bar,l8 approaches within a predé'termined dis end and resiliently urging the sleeve forward to tance, of the work, I5 and of the front extremity project beyond end or forward portion 15 of the of sleeve 14., This-distance, which corresponds bucking bar. 7 . 60 to the height of the completed rivet, remains uni To prevent accidental loss or undue displace form'in successive operations as long, as the ele ment of the sleeve, a retaining pin at is secured . ments of the device remain in their adjusted in the forward portion 75 ofthe bucking bar with position. To increase (or decrease) the ‘height the upper end extending into a longitudinal slot 82 in said sleeve and thus limiting movement of 6.5 of thef?nished rivet, the adjustable screw 85 is turned to a more rearward (or more forward) the latter to the extent allowed by the pin in said position in post 84. , , / . slot. An aperture 83 in the bottom of the sleeve A slightly different starting of the cycle is not affords access in one position of the latter to the only possible but occurrence thereof is also likely lower end of the pin when the same is to here moved for repairs or replacement of parts. Upon 70 to be more or less frequent, for it may well be that the bucker is ready before the riveter and the rear of the enlarged portion 76 of the sleeve ‘i4 by haste or misinterpretation of a signal and is ?xed a screw post 84 in which is mounted an with .the bucking mechanism in position, may de adjustable screw 85 adapted to engage against the press the manual operating lever 52 to open valve forward end 86 of the release slide member :58 in 36 in the hammer mechanism before the latter manual operating lever ~52 in all positions of the 75 is in position and thetrigger is ‘pressed. by “the 2,411,561 riveter to open throttle valve 24. Depressing said operating lever will not alone cause operation of the hammer, and will thus not occasion pre mature movement of any part of the assembly nor cause damage to the work piece involved, but actual operation is merely delayed until the riv eter has the hammer anvil in place on the rivet 8 ated hammer, supply means for conducting pres sure ?uid to said hammer, a control valve asso ciated with said hammer for controlling the ?ow of the ?uid through said supply means to the hammer, actuating means for said control valve including a ?exible cable comprising a core and a sheath surrounding the same, the core being movable with reference to the sheath upon the application of pressure to an end thereof having hammer will operate and the cycle will proceed 10 one actuating portion thereof extending into and be completed as previously described. cooperative relation with said valve and having Manifestly, modi?cations are possible and may another actuating portion associated with the be resorted to, and parts may be altered in size bucking bar and movable with respect thereto, or form and used without others, within the scope operable means upon said bucking bar for impart of the invention as de?ned in the appended ing movement to said actuating means and there claims. by opening said control valve, and a movable What is claimed is: releasing member supported upon said bucking 1. A riveting assembly, comprising a ?uid pres— bar automatically effective during operation to sure operated hammer, a bucking bar, said ham disable said operable means and release the mo mer and said bar being carried by separate oper ators and adapted to engage a rivet on opposite 20 tion transmitting means and thereby cause said control valve to be closed upon completion of a sides of the work, and means causing the opera predetermined'amount of set upon said rivet. tion of said hammer to be under the control of 4. A riveting assembly, comprising a ?uid pres the hammer operator in dependence upon inde sure operated hammer, a bucking bar, said ham pendently operable remote control from the buck: mer and said bar being carried by separate oper ing bar in order to prevent damaging the rivet ators and adapted to engage a rivet on opposite or the work by premature hammer operation, said sides of the work, supply means for conducting means comprising a ?rst ?uid pressure control pressure ?uid to said hammer, a throttle valve valve and local means associated with the ham associated with said hammer for controlling the mer for opening said valve at will, a second ?uid pressure control valve in series with said ?rst 30 ?ow of ?uid through said supply means, an aux iliary valve for controlling the ?ow of ?uid valve and capable of being opened independently through the same supply means, said valves coop of the operation of the first valve, and mechani erating to cut off the ?ow of ?uid to said ham cal operating means on said bucking bar capable mer when either or both of said valves are closed, of becoming automatically effective during oper local operable means associated with said ham ation to close said second valve upon production mer for controlling said throttle valve, actuating of a predetermined amount of set upon said means for said auxiliary valve including a ?ex rivet, said mechanical operating means on said ible motion transmitting means having one actu bucking bar acting through a ?exible cable com ating portion extending into cooperative relation prising a sheath attached at one end to said with said auxiliary valve and having another hammer and at the other end to said bucking bar actuating portion associated with the bucking and containing a movable core extending into bar and movable with respect thereto, operable cooperative relation at one end with said aux means upon said bucking bar for operating said iliary valve and at the other end extending to motion transmitting means and thereby opening said hammer. 2. A riveting assembly, comprising a ?uid pres 45 said valve, and a movable contacting member mounted on said bucking bar for engaging against sure operated hammer, a bucking bar, said ham the work in the vicinity of the rivet to be set, mer and said bar being under separate control and a shiftable releasing member engaged by a and adapted to engage a rivet on opposite sides portion of said contacting member and capable of the work, supply means for conducting pres of neutralizing said operable means and releas sure ?uid to said hammer, a throttle valve asso 50 ing said motion transmitting means and there ciated with said hammer for controlling the ?ow by cause the auxiliary valve to be closed upon oc of pressure ?uid through said supply means, an currence of a predetermined relative change in auxiliary‘ valve for controlling the ?ow of ?uid position between said bucking bar and contact through the same supply means, said valves coop ing member caused during operation due to the erating to cut off the ?ow of ?uid to said ham 55 progressive shortening of the rivet by the produc head and then presses the trigger l3, when the mer when either or both of said valves are closed, tion of a predetermined amount of set upon said local operable means associated with said ham rivet. ber for controlling said throttle valve, actuating 5. A riveting assembly, comprising a ?uid pres means for said auxiliary valve including a ?ex ible cable sheath extending between said ham 60 sure operated hammer, a bucking bar, said ham mer and said bar being carried by separate op mer and said bucking bar and containing a mov able core operable at one end as a movable plung er from said bucking bar and at the other end erators and adapted to engage a rivet on oppo site sides of the Work, supply means for conduct ing pressure ?uid to said hammer, a throttle valve extending into cooperative relation with said auxiliary valve, operative means upon said buck 65 associated with said hammer for controlling the ?ow of ?uid through said supply means, an aux ing bar for moving said core and thereby open iliary valve for controlling the flow of ?uid ing said auxiliary valve, and movable means through the same supply means, said valves co associated with said bucking bar capable of be operating to cut off the flow of fluid to said ham coming automatically e?ective to neutralize said operative means and release said core in order to 70 mer when either or both of said valves are closed, local operable means associated with said ham cause said auxiliary valve to be closed upon com mer for controlling said throttle valve, actuating pletion of a predetermined degree of set upon means for said auxiliary valve including a ?exi said rivet. ble motion transmitting means having one end 3. In a riveting assembly, a bucking bar adapt ed for cooperation with a ?uid pressure oper 75 portion extending into cooperative relation with 2,411,561 . - ’ 9 said auxiliary valve and having the other end portion associated with the bucking bar and mov~ able with respect thereto, manually operable means upon said bucking bar including a depress a . 10 means for said auxiliary valve including a ?exible motion transmitting means having one end por tion extending into cooperative relation with said auxiliary valve and having the other end por ible member-mounted in effective position to move a GI ' tion associated with the bucking bar and mov said other end portion of said motion transmit ting means to open the auxiliary valve, resilient able With respect thereto, manually operable means upon the bucking bar including a depress means tending to return said depressible member ible ‘lever pivotally mounted in a position effec to initial position when released, a movable con tact member slidably mounted upon said bucking 10 tive to move said other end portion of said mo tion transmitting means to open the auxiliary bar for engaging against the Work, and a shift valve, resilient means tending to return said mo able releasing member associated with said de tion transmitting means in closing direction to pressible member and engaged by a portion up initial position of said auxiliary valve, a movable on said contact member in effective position to contact member including a sleeve slidably mount be shifted relatively to said depressible member ed on said bucking bar, resilient means tending and neutralize the latter with consequent release to cause a portion of said sleeve to project be of the motiontransmitting means and corre yond the working end of the bucking bar to make sponding closure of the auxiliary valve upon 00 direct contact with the work, resilient means also currence of a predetermined relative change in tending to returnsaid lever to initial position position between said bucking bar and contact 20 when released, a shiftable releasing member slid member due to the progressive shortening of the v rivet caused during operation by production of a predetermined amount of set upon said rivet. 6. In a riveting assembly, a bucking bar adapt ed for cooperation With a ?uid pressure operated hammer, supply means for conducting pressure fluid to said hammer, a valve for controlling the ?ow of ?uid through the supply means, actuat ably lmounted ‘on‘said lever so as to partake of the pivoting movements thereof and normally al low the lever upon depression thereof to impart movement to the motion transmitting means and thereby cause opening of the auxiliary valve, and a projecting portion upon said slidably mounted , sleeve engaging said releasing member at least in depressed. position of said lever and capable tion transmitting means having one end portion 30 of neutralizing the effect of said lever in said depressed position with consequent release of the extending into cooperative relation with said motion transmitting means and closure of the valve and having the other end portion associated auxiliary valveupon occurrence of a predeter with the bucking bar and movable with respect mined change in relative positions between said thereto, manually operable means upon the buck_ ing means for said valve including a ?exible mo ing bar including a depressib-le lever pivotally mounted in a position e?ective to move said other sleeve. and bucking bardue to the progressive shortening of the rivet caused during operation by production of a predetermined degree of 'set end portion of said motion transmitting means‘ ' upon said rivet. ‘ ' to openthe valve, resilient means tending to return 8.'A riveting assembly according to claim 7, ' said motion transmitting means in closing direc tion to initial position of said valve to close the an in which the releasing member is disposed with in a porticnof, and carried by, the pivotally latter, a movable contact member slidably mount mounted lever and has one end thereof directed ed on said bucking bar, resilient means tending toward the pivoted end of the lever and engaged to cause said contact member to'project beyond by the projecting sleeve portion serving as a re the working end-of the bucking bar to make cli action point for shifting said member. rect contact with the work,'said depressible le- ' 9. A riveting assembly according to claim '7, ver also tending to be returned to initial posi in which the releasing member has‘one vend there tion when released, and a shiftable releasing mem of disposed adjacent to the pivoted end of the ber associated with said depressible lever and lever and engaged by the projecting sleeve por engaged by a portion upon said contact member tion serving as a reaction point for shifting said in effective position to be shifted relatively to member, and in which resilient means carried said lever in order to neutralize the latter with by the lever serves to urge said releasing member consequent release of the motion transmiting resiliently toward said projecting sleeve portion. means and closure of the valve upon occurrence 10. A riveting assembly according to claim '7, during operation of a predeterminedv relative change in positions between said bucking bar and ‘ contact member due to the progressive shortening of‘ the rivet caused by the production of a ?nished settingupon saidrivet. ' > > , ' » in which the releasing member normally forms the means upon the pivoted lever which directly engages with a projecting portion upon the end 7 of the motion transmitting means,’ and in which said releasing member has a gap portion which 7. A riveting assembly, comprising ‘a ?uid pressure operated hammer, a bucking bar, vsaid 60 registers with said projecting portion upon the end of said motion transmitting means in shifted hammer and said bar being carried by'separate operators and adapted to engage a rivet on cp posite sides of the work, supply means for con ducting pressure ?uid to said hammer, a throttle valve associated with said hammer for control ling the ?ow of ?uid through said supply means; an auxiliary valve for controlling the ?ow of ?uid through the same supply means, said valves co operating to cut off the ?ow'of ?uid to the ham mer when either or both of said valves are closed, local operating means associated with said ham mer forcontrolling said throttle valve, actuating - position of said releasing member, said gap por tion releasing said motion transmitting means and allowing the same by entrance of the project ing end thereof into said gap portion to return to 'initial position and close the auxiliary valve. 11. A riveting assembly according to claim 7, in which stop means are included for limiting movement of the sleeve to a predetermined range, and in which the projecting portion on said sleeve includes an adjustable abutment member. EDWARD w. STEVENS.