US3055344A

US3055344A - Fastener applying implement

Info

Publication number: US3055344A
Application number: US16702A
Authority: US
Inventors: Edward I Fisher
Original assignee: Bostitch Inc
Current assignee: Bostitch Inc
Priority date: 1960-03-22
Filing date: 1960-03-22
Publication date: 1962-09-25
Anticipated expiration: 1979-09-25

Description

Sept. 25, 1962 E. l. FISHER 3,055,344

FASTENER APPLYING IMPLEMENT Filed March 22, 1960 3 Sheets-Sheet 1 .INVENTOR. ql N ATTORNEYS Sept. 25, 1962 E. FISHER 3,

FASTENER APPLYING IMPLEMENT Filed March 22, 1960 5 Sheets-Sheet 2 INVEN TOR.

E'W rdZJ Qefiez ATTORNEYS Sept. 25, 1962 E. l. FISHER FASTENER APPLYING IMPLEMENT 3 Sheets-Sheet 3 Filed March 22, 1960 m m m m ATTORNEYS stats This invention relates to improvements in fastener driving machines and appliances and more particularly to a piston driven implement actuated by pressure fluid, for example pneumatically by air pressure.

One object of the invention is to provide a machine of the type indicated which is simple in construction, compact in size, and of relatively light weight to render it usable as a portable implement.

Another object is to provide a machine of the type indicated embodying a piston reciprocated by pressure fluid, either pneumatic or hydraulic, for actuating the driving means under constant power throughout a complete driving stroke and its return to initial position.

Another object is to provide in a machine of the type indicated a main reservoir of large capacity for compressed air or other pressure fluid with manually operable means for controlling the pressure applied to the piston.

A particular object of the invention is to provide means for applying the pressure to the underside of the piston for returning it to first position after each driving stroke so as to avoid the use of a spring for raising the piston.

Another object is to provide means for returning the piston to first position after each driving stroke by applying pressure directly to the underside of the piston without the use of auxiliary means such as a supplemental piston connected to the main piston and operative in a separate cylinder.

Another object is to provide means accessible on the outside of the machine for adjusting the connection between the driver and the piston to vary the effective length of the driver in accordance with the type of work to be performed.

Another object is to provide a machine of the type indicated operated under constant power with maximum impact capacity for driving relatively large staples or similar fastening elements.

Further objects and advantages of the present improvements are set forth in the following specification or will be obvious to those skilled in the art; it being understood that the present disclosure is by way of example only to illustrate a preferred embodiment of the invention as shown by the accompanying drawings. In the drawings:

FIG. 1 is a side elevational view of the complete implement part-sectional in a plane intersecting the vertical axis of the machine and showing the driving piston as raised in normal relationship;

FIG. 2 is a similar sectional view of the fore part of the machine also showing the piston in raised relationship but with the exhaust valve at the bottom of the cylinder open for venting the pressure beneath the piston;

FIG. 3 is a similar sectional view of the fore part of the machine showing the piston depressed with the driver element at the end of its stroke and the manually operable control valve closed;

FIG. 4 is a transverse sectional view through the top 3,055,344 Patented Sept. 25, 1962 of the cylinder of the machine taken on line 4-4 of FIG. 1;

FIG. 5 is a transverse sectional view on line 5-5 of FIG. 1 showing the adjustable connecting means between the driver blade and the piston;

FIG. 6 is a bottom plan view of the base of the cylinder on line 6-6 of FIG. 1 showing the arrangement of the gland means through which the driver blade slides and also illustrating the under side of the exhaust valve which acts to vent the cylinder beneath the piston; and

FIG. 7 is an enlarged bottom plan view of the manual control poppet valve for admitting pressure into the bottom of the cylinder to raise the piston.

While the present invention is herein illustrated and described in the form of a portable, pneumatically-operated implement, it is to be understood that it may be embodied in other structures such as a stationary machine mounted on a suitable base or standard. As at present disclosed the implement may be employed in many different industries for fastening together various objects and articles by driving staples to attach the parts of automobile bodies, fastening the covers to boxes and cases, tacking or nailing sheathing and roofing to buildings, and for fastening together numerous other articles and objects.

As herein illustrated, the implement is of conventional design comprising a casing A having a head H containing the operating mechanism and surmounting the forward end of a magazine M of usual construction for containing inverted U-shaped fasteners such as wire staples S. The forward end of the magazine M is fastened to the base of the head H by suitable means with a nosepiece N formed with a slotted throat or guideway 11 in which the staple driver D reciprocates. The nosepiece N may form a part of a bifurcated bracket T having lateral flanges F at the top abutting a closure plate P at the base of the head H and suitably fastened thereto. The closure plate *P may be fastened to the bottom of the walls of the head H by screws 1 (FIGS. 1, 2) to provide for its removal for assembling the operating elements therein. The magazine M extends rearwardly from the nosepiece N and as usual is of U-shape formed of sheet-metal folded to provide a hollow structure. Fastened within the magazine M is a l-ongitudinally-extending core or support C on which the staples S are mounted to slide forwardly for feeding the foremost staple of the series into the throat or guideway n in which the staple driver D slides. A staple pusher J of usual construction is slidably mounted on the core C and urged forwardly by a suitable spring (not herein shown) for advancing the staples to deliver them singly to the driving means; these last-named elements of the machine not being described in detail herein as they form no part of the present invention.

The main casing A of the machine may be constructed as a casting comprising the vertical head H containing a cylinder 2 at the bottom surmounted by a generally flaring inner chamber or pressure fluid reservoir 3. The walls of the chamber 3 art the stop of the head are conrtinued rearwardly in the form of a hollow handle 4- by which the implement may be grasped in the hand for transporting it and holding its nose N against the work. Compressed air or other pressure fluid may be supplied to the reservoir 3 in the head H by connecting the end of the handle 4 to a hose [1 leading from a suitable source thereof. It is to be noted that the interior of the handle 4 opens into the pressure chamber 3 through an orifice 5 of relatively large area so that constant pressure is maintained within the reservoir. The casing of the implement may be constructed as a casting with the pressure chamber 3 and the interior of the handle 4 cored out "for the sake of economy in the cost of manufacture so that only the cylinder 2 for the piston needs to be machined to provide a smooth-walled bore.

The upper open end of the cylinder 2 is flanged inwardly at 8 and formed with interior groove 9 in which is mounted a flexible gasket 10. The cylindrical piston 7 is preferably of hollow construction, open at the top and closed at the bottom by a relatively thick wall 1'1. The lower wall 11 of the piston 7 is shouldered on the outside at 12 to project outwardly lior increasing its bottom area and thus provide a differential relationship with the area on its upper surface. A groove 13 is formed in the periphery of the projecting portion of the wall 11 and has a flexible gasket 14 held therein. A second gasket 15 mounted above the projecting rim 12 at the bottom of the piston 7 seats against the shoulder of the enlargement 12 with both gaskets in slid-able contact with the inner wall of the cylinder 2 to form a seal between the piston and the cylinder.

For different kinds of work it has usually been found of advantage to adjust the connection between the driver blade and piston for changing the relationship of the lower driving edge of the blade so as to regulate the extent of its driving stroke for inserting the staples into the work. That is to say, in certain kinds of work the staple crown is embedded slightly in the material of the work; whereas, in other cases the effective extent of the driver below the piston may be reduced in accordance with the type of operation being performed. In practically all machines now in use adjustment of the connection between the staple driver and piston to regulate the effective length of the driver has only been possible by opening the casing of the machine and disassembling parts of its mechanism. In the present improved construction, however, the head of the machine is entirely closed after the operating parts have been assembled therein and means conveniently accessible on the outside of the machine are provided for adjusting the driver blade vertically in relation to the piston without opening the oasing. The novel and ingenious means for effecting this advantageous result are constructed and arranged as next described.

The staple driver D is in the form of 1a flat metal blade provided at the top with a transverse enlargement or cylindrical bead 16 engageable in a drilled hole 17 extending diametrically through a threaded stud or plug 20. The plug 20 is screwed into a bore 21 in the bottom wall 11 of the piston 7 with the flat portion of the driver engaging in a slot 22 below the hole '17. By the present improved construction relative turning motion between the piston 7 and the plug 20 will effect micrometer-like adjustment of the driver blade D to raise or lower its driving end in relation to the piston. The threaded plug 20 is formed with a disk-like head 23 connected to its upper portion by a square neck 24 (FIGS. 1, 5). The neck 24 of the plug 20 provides means cooperating with a hairpin-shaped pawl 25 arranged with its legs resiliently engaging its flat sides to act as detent means tor preventing unwarranted rotary movement of the piston 7. A relatively long pin 26 held in a drilled hole in the base 11 of the piston 7 projects upwardly therefrom through the pawl 25 to adapt it to engage with its legs for limiting the turning of the piston in the bore of the cylinder 2.

For rotating the piston 7 about its axis in the cylinder 2 to adjust the relationship of the driver thereto, manually operable means are provided accessible above the top of the head H in the form of a finger-grip 30. Fastened to the under side of the finger-grip 30 is a stud 32 (FIG. 1) by which it is rotatively mounted in a bore 33 in the top closure wall of the head H. The stud 32 is secured to the finger-grip 30 by its reduced knurled end 33 forced into a hole therein. Held in a slot in the periphery of the stud 32 is a flexible gasket 34 engaging the interior of the bore 33 for sealing the joint therebetween. The lower end of the stud 32 is formed with a disk-like head 35 engaging in a finished recess 36 on the under side of the top closure wall of the head H. A thin metal strip 37 is held in a transverse slot on the under side of the enlarged head 35 with its ends projecting radially therefrom to provide a key-like wrench. The projecting ends of the member 37 are adapted to engage in pairs of diametrically-opposed slo'ts 4t) and 4141 in the upper rim of the piston 7 to provide for turning the piston 7 about the screw-threaded plug 20 to adjust the vertical relationship between the driver D and piston; that is, for either increasing or decreasing the effective length of the driver to regulate the distance of its operating end from the piston. It is obvious that the driver blade D is prevented from turning when the piston 7 is rotated due to its engagement with the sides of the throat n in the nosepiece N. The operation of the above described means tor adjusting the connection between the driver blade D and the piston 7 is as next explained.

Assuming the piston 7 to be at the upper end of its stroke as shown in FIGS. 1 and 2, the finger-grip 30 will normally be raised with the key element 37 above the slots in the end of the piston 7. By simply pressing the finger-grip 30 downward the ends of its key 37 may be engaged with either pair of slots 40-40 or 41-41 in the upper rim of the piston 7; it being observed by reference to FIG. 4 that said slots are of somewhat greater extent than the width of the key 37 to render it convenient for engaging the key with the slots. For example, even though neither pair of slots may be in alinement with the ends of the key 37, a slight turning movement of the finger-grip 30 will position the key for engagement with one pair of slots as it is pressed downwardly by the operator. After the key 37 has been entered in the slots 40 40 or 41-41, as the case may be, the piston 7 may be rotated by the finger-grip, either clockwise or counter-clockwise, to a sufficient extent to effect the desired adjustment between the driver blade and piston. As the piston 7 is rotated the pin 26 in its interior will engage one or the other of the legs of the pawl 25 to swing the latter around until its legs come into engagement with certain of the opposite sides of the square neck 24 of the plug 20. With the adjustment completed the pawl 25 will act as detent means to prevent further unwarranted turning of the piston 7 in the cylinder 2; although a limited amount of rotary motion of the piston is permitted during its reciprocation as usually considered desirable.

It will be understood that the piston 7 may be rotated through an arc of from to 360, or even several turns more to efiect the desired extent of relative vertical adjustment between it and the driver blade D. In any case, the preferred practice is to rotate the piston until the opposite legs of the pawl 25 snap into engagement with certain of the opposed fiat sides of the neck 24 on the plug 20 to prevent it from further unwarranted turning. Even though this engagement is not completed the detent means still will act to prevent excessive rotary movement of the piston with respect to the threaded stud 20 which connects it with the driver blade D. Through this ingenious construction of the present improved micrometer adjusting means, the relationship between the driver blade D and piston 7 can be regulated with extreme accuracy without opening the head H or disassembling any parts of the machine.

To relieve shock and jar on the piston 7 as it descends in the cylinder 2 a resilient washer or bumper 50 is dis posed in the bottom of the cylinder seated on the closure plate P. The bumper may be constructed of rubber or other suitable resilient material with a central slotted opening 52 in alinement with a slot 53 in the plate P through which the driver slides. The opening 52 at the center of the bumper 50 is enlarged at the top and of peculiar formation with a relatively deep lip (FIG. 6) surrounding the driver blade D and having its marginal edge impinging resiliently thereagainst. This formation of the opening 52 for the driver blade D provides a gland for preventing escape of the air therethrough when pressure is applied to the bottom of the piston 7 for returning it to initial position at the upper end of the head H.

As will be seen by reference to the drawings, the upper chamber or reservoir 3 in the head H of the casing A is in direct communication with the hollow interior of the handle 4 through an unrestricted orifice 5 of relatively large area so that constant maximum pressure is supplied to the reservoir 3 at all times. It has been stated that the area on the bottom of the piston 7 is greater than the area on the upper surface of its bottom wall 11 so a differential pressure relationship normally maintains the piston at the upper end of its stroke when air is admitted into the cylinder 2 below the piston. For controlling the admission of pressure into the bottom of the cylinder 2, a poppet valve, indicated generally at 68' and next described, is provided in the handle 4 of the machine.

At the forward end of the handle 4 its bottom wall is formed with an inclined tubular valve casing 61 in which is mounted a closure element or poppet 62. Opening from the interior of the chamber '3 and handle 4- into the casing 61 is an inlet port '63 (FIG. 3), adapted to be closed by the enlarged head 64 of the poppet 62. The head 64 is grooved peripherally to receive a pair of resilient gaskets 65 and 66 on opposite sides of a flange 67. The lower portion of the poppet 62 is of triangular formation in cross-section, as shown most clearly in FIG. 7, to provide relief passages through the bore 71 of an annular member or collar 68 held in the interior of the easing 61 by means of a flat washer 69. The annulus 68 is formed with a peripheral groove in which a flexible gasket 70 is held for sealing the joint between the annulus 68 and the interior wall of the casing 61. It will be noted that the interior of the valve casing '61 is open to the atmosphere through the annulus 68 and a relatively large orifice 72 in the lower wall of the handle 4. The poppet valve 68 may be operated manually by means of a trigger 75 pivoted at 76 in a slot 77 in the bottom wall of the handle 4. The top of the trigger 75 is formed with a triangularlyshaped lug 78 adapted to engage the lower end of the poppet 62 to slide it upwardly in the casing 61 (FIG. 3) with the gasket 65 seating against the bottom rim of the port 63 to close the port. On the other hand, the gasket 66 acts to seat across the end of the bore 71 in the annulus 68 when the poppet is withdrawn to its normal relation ship as shown in FIG. 1. I

Leading downwardly from the interior of the valve casing 61 is a vertical duct 81 which opens into a supplemental valve chamber 82 formed by a circular casing 83 constructed integral with the wall of the cylinder 2 and projecting laterally therefrom above the magazine M. The chamber 82 is partially closed at the bottom by the plate P fastened to the base of the head H, but is provided with a relatively large circular orifice 84 for exhausting pressure from the lower end of the cylinder 2 into the atmosphere. For this purpose the wall of the cylinder 2 is provided at the bottom with an opening 85 communicating with the chamber 82.

A small shaft or spindle 86 projects down into the chamber 82, being held axially thereof by means of its reduced threaded end 87 passing through a hole in the top of the casing 83 and secured by a nut 88. Mounted to slide vertically on the spindle 86 within the chamber 82 is a valve closure 90 in the form of a relatively thick disk. A resilient gasket 91 held in an inner groove near the top of the bore in the valve closure 90 acts to seal the joint between the closure and the spindle 86. The valve closure 90 is also formed near the top with a relatively large peripheral groove 92 for containing an annular gasket 93. The gasket 93 is of bifurcated form in cross section, being provided with two resilient lips 95, the outer one of which engages the interior wall of the casing 83 to seal the joint at this point while adapting the closure to slide up and down on the spindle 86. At the bottom of the closure element 90 is a deeper peripheral groove holding a flat washer or resilient gasket 96 with its outer rim projecting beyond the periphery of the closure to adapt it to seat against the rim of the exhaust orifice 84 in the bottom of the chamber 82 (FIG. 1). With the parts in position as last explained, the lower end of the duct 81 opens into the chamber 82 and the pressure fluid is free to flow past the gasket 93 by compressing its lips to pass downwardly into the bottom of the cylinder 2 through the opening 85 in the side thereof. Having now described the construction and arrangement of the various parts of the machine, its method of operation is explained as follows.

It will be understood that the operating mechanism of the machine is assembled within the head H through its bottom opening before the closure plate P and the magazine M are attached thereto. Therefore, no opening is necessary at the top of the head for assembling the operating parts therein as in conventional machines at present in use. It is also to be noted that the parts of the poppet valve 60 may be assembled through the opening in the bottom of the handle 4 before the trigger 75 is pivoted in position. Moreover, in the present improved construction, access may be had to the means for adjusting the connection between the driver and piston to vary the extent the driver blade D projects downwardly from the piston 7 in accordance with difierent requirements of the work. The method of adjusting the relationship between the driver blade and piston has been explained in detail and therefore needs no further mention at this point.

Assuming that the magazine M is charged with staples S, herein shown are of large size for industrial use; and that the reservoir in the handle 4 is connected by the hose h to a suitable source of pressure fluid such as compressed air, the implement may be grasped in one hand for transporting it to the work. Normally, the piston 7 will be in its uppermost position (FIG. 1) with the driver D raised above the top of the foremost staple S in the guideway or throat n at the forward end of the magazine M. The piston 7 is normally sustained in its raised position by pressure thereunder admitted into the bottom of the cylinder 2 as the inlet port 63 of the poppet valve 60 is held open. That is to say, pressure from the reservoir 3 and handle 4 flows through the inlet port 63 past the poppet 62 and thence from the valve 60 down through the duct 81 into the supplemental valve chamber 82. From the chamber 82 the air flows past the valve closure 90 which remains seated around the exhaust orifice 84. Consequently, the air or other pressure fluid is admitted into the lower end of the cylinder 2. through the opening 85 at the bottom thereof and applied against the under side of the piston 7 to act on the larger area thereof for causing the differential relationship to sustain the piston raised. The machine may be applied to position above the work by holding its nose N thereagainst; or in other cases, the implement may be tilted and placed in position with the nose against a vertical or inclined face of the work.

After the implement has been applied to the work it is only necessary to operate the valve 60 by placing the forefinger under the trigger 75 and lifting it for sliding the poppet 62 upwardly. This action causes the head of the poppet 62 to be seated for closing the inlet port 63 (FIG. 3) to cut ofl? the flow of air to the under side of the piston 7. At this juncture the pressure in the supplemental valve chamber 82 above the valve closure 98 is released to flow upwardly through the duct 81 and down through the outlet passage 71 in the valve 60 and exhaust to the atmosphere. Consequently, the pressure in the upper reservoir 3 acting on the piston 7 will drive it downwardly in the cylinder 2. Meanwhile, as the piston 7 is driven downwardly the pressure therebeneath will be forced out through the opening 85 at the bottom of the cylinder 2 and acting against the bifurcated gasket member 93 it will force the valve closure 90 upwardly, thereby opening the exhaust orifice 84 to allow pressure to escape therethrough to the atmosphere. Through this method of operation the pressure beneath the piston 7 is immediately relieved and the piston is rapidly driven downward to operate the driver D with a sharp impact against the staple for separating it from the stick to which it is connected and driving the full length of its legs into the work. The machine may thus be operated continuously to apply staples or other fastening means at a rapid rate until the charge of fasteners in the magazine is exhausted.

After each operation of the staple driving means the trigger 75 is released to cause the poppet 62 to slide downwardly for opening the inlet port 63 at the upper end of the valve casing 61. Pressure from the reservoir 3 and the interior of the handle 4 will once again flow down through the duct 81 to force the valve closure 96 down in the supplemental valve to seat it for closing the exhaust orifice 84. Therefore, with the exhaust orifice 8 5 closed the air will flow into the bottom of the cylinder 2 for raising the piston and again sustaining it in its uppermost position as shown in FIG. 1. As the piston 7 ascends to carry the driver blade D upwardly in preparation for another driving stroke, the sides of the driver are maintained in contact with the resilient lips 55 to seal the opening 52in the bumper 50 so that leakage of pressure at this point is prevented.

It will be observed from the foregoing specification that the present invention provides an extremely simple form of construction of the machine with its operating mechanism contained in a light-weight, compact casing herein shown in the form of a manually transportable element. On the other hand, it is to be understood that the present disclosure is intended to illustrate one preferred form of the invention by way of example as the improvements may be embodied in other constructions such as a stationary machine for use on a bench or other support.

While the present improvements are shown and described as embodiment in apreferred form of construction, it is to be understood that various modifications may be made therein without departing from the spirit or scope of the invention as set forth in the accompanying claims. Therefore, without limiting myself in this respect, I claim:

1. In a piston-operated machine, a casing having a reservoir for pressure fluid and a cylinder in communication therewith, a piston reciprocable in said cylinder, said piston having a greater area on its under side than on its upper side opposed to pressure in said reservoir, a valve having an inlet port opening into said reservoir and an exhaust passage leading to the atmosphere, means connecting the interior of said valve with a supplemental valve having a passage in communication with one end of said cylinder, said supplemental valve having an exhaust orifice opening into the atmosphere, manually operable means for closing the inlet port in the first named valve and opening the exhaust passage therefrom to drive the piston in an operative stroke, and a valve closure in said supplemental valve actuated by fluid pressure from said first named valve when its inlet port is open to close the exhaust orifice in said supplemental valve and admit pressure into the end of the cylinder for returning the piston to initial position after each driving stroke.

2. In a piston-operated machine, a casing having a reservoir for pressure fluid and a cylinder in communication therewith, a piston reciprocable in said cylinder, said piston having a greater area on its under side than the area on its upper side to provide differential force potentials, a valve adjacent said reservoir provided with an inlet port communicating therewith and an exhaust passage opening therefrom into the atmosphere, manually operable means for closing said inlet port in said valve and simultaneously opening said exhaust passage therefrom, a supplemental valve having a passage leading from the interior of said first named valve and an exhaust orifice opening into the atmosphere, said supplemental valve having a passage opening into one end of said cylinder for admitting fluid pressure from the first named valve to normally maintain said piston in inactive relationship, and a valve closure in said supplemental valve actuated by fluid pressure from said first named valve to maintain the exhaust orifice in said supplemental valve closed and the passage into the cylinder open to admit fluid pressure thereinto for returning the piston to initial position after each operative stroke when said inlet port in the first named valve is opened.

3. In a piston-driven machine, a casing having a reservoir for pressure fluid and a cylinder in communication therewith, a piston reciprocable in said cylinder, said piston having a greater area on one side than its area opposed to the fluid pressure in said reservoir to provide a differential relationship therebetween, a driver element connected to said piston, a valve having an inlet port leading from said pressure chamber and an exhaust passage opening into the atmosphere, a supplemental valve having an opening into one end of said cylinder, a passage leading from said first named valve into said supplemental valve for transferring pressure thereto, an exhaust orifice in said supplemental valve opening into the atmosphere, manually operable means for closing the inlet port in said first named valve and opening the exhaust passage therefrom, and a valve closure in said supplemental valve normally operable by pressure through the passage leading from said first named valve to close the exhaust orifice in said supplemental valve and admit pressure through the opening leading into the end of the cylinder for sustaining the piston in initial relationship until the inlet port in said first named valve is closed.

4. In a pneumatically operated machine, a casing having a head with a reservoir for compressed air therein, a cylinder extending longitudinally of said head with its upper end in communication with said reservoir, a piston reciprocable in said cylinder, said piston having a greater area at one end than its area opposed to the air pressure in said reservoir, a valve adjacent the top of said cylinder with an inlet port opening into said air reservoir and an exhaust passage leading to the atmosphere, a poppet in said valve movable to close said inlet port and simultaneously open said exhaust passage, a duct opening from the interior of said valve and extending downwardly therefrom, a supplemental valve at the end of said duct adapted to receive air pressure from said first named valve when its inlet port is open to thepressure in the reservoir, said supplemental valve having an opening leading into the end of said cylinder and an exhaust orifice opening into the atmosphere, and means for manually operating said first named valve to close its inlet port and open its exhaust passage, whereby to release perssure against the valve closure in the supplemental valve to cause pressure from the cylinder to open the exhaust orifice therein for relieving pressure against the piston in its descent during an operative stroke.

5.'In a fastener applying machine, a casing having a pressure fluid reservoir therein, a cylinder in said casing in communication wtih said reservoir, a piston reciprocable in said cylinder by pressure from said reservoir, said piston having a greater area on one side than its area opposed to the pressure in said reservoir to provide a differential relationship therebetween, a driver reciprocable by said piston, a poppet valve having an inlet port in communication with said pressure reservoir and an exhaust passage opening into the atmosphere, said poppet valve connected to a duct leading toward the bottom of said cylinder, a supplemental valve at the end of said duct having an opening leading into the bottom of said cylinder and an exhaust orifice opening into the atmosphere, a valve closure in said supplemental valve movable to open the exhaust orifice thereof, or to alternately close said exhaust orifice, and manually operable means for actuating said poppet valve to close its inlet port and open its exhaust passage to cause the pressure from the bottom of the cylinder to actuate said closure for opening the exhaust orifice in said supplemental valve during the descent of the piston.

6. In a fastener applying machine, a casing having a head with a reservoir for pressure fluid in the upper portion thereof, a cylinder in said head in communication with said fluid pressure reservoir, a piston reciprocable in said cylinder, a driver connected to said piston for reciprocation thereby, a poppet valve having an inlet port leading from said fluid pressure reservoir and an exhaust opening communicating with the atmosphere, a poppet in said valve slidable to close said inlet port and uncover the exhaust opening to the atmosphere, manually operable means for actuating said poppet to close said inlet port, a supplemental valve at the bottom of said head having an opening leading into said cylinder and an exhaust orifice communicating with the atmosphere, a duct leading from said poppet valve and opening into said supplemental valve, a closure in said supplemental valve movable under pressure through said duct to close said exhaust orifice, said valve closure movable in the opposite direction to open said exhaust orifice when said piston descends in the cylinder to release back pressure thereon, said poppet being normally held in position in the first named valve with the inlet port open to pressure from said reservoir and the exhaust opening closed whereby pressure flowing through said duct is admitted to the bottom of said cylinder for raising the piston due to the differential relationship between its under side and its side opposed to the force of pressure in the reservoir.

7. In a fastener applying machine having a head with a pressure fluid chamber therein, a cylinder in communication with said pressure chamber and extending downwardly therefrom, a piston reciprocable in said cylinder, said piston provided with a greater area on its under side than the area thereabove opposed to the force of pressure in said chamber, a driver connected to said piston for reciprocation thereby, a valve adjacent said pressure chamber with an inlet port leading therefrom, said valve having an exhaust opening communicating with the atmosphere and normally closed when said inlet port is open, a duct leading from said valve downwardly at the side of said cylinder, a poppet slidable in said valve to close said inlet port and open said exhaust opening to the atmosphere, a trigger for manually operating said poppet, a supplemental valve at the end of said duct for receiving pressure fluid from the first named valve when said inlet port is open, an exhaust orifice in said supplemental valve for releasing pressure to the atmosphere, an opening leading from said supplemental valve into the bottom of said cylinder, and a valve closure in said supplernental valve normally operated by pressure from said first named valve to close the exhaust orifice to the atmosphere, said valve closure being operated by pressure from the bottom of the cylinder during the descent of the piston to open the exhaust orifice in the supplemental valve.

8. In a machine of the type indicated, a casing having a head with a pressure chamber therein, a cylinder in said head having an opening at the top in communication with said pressure chamber, a piston reciprocable in said cylinder and constructed with a greater area on its under side than its area opposed to the pressure from said chamber, a valve in said casing, an inlet port in said valve opening from said pressure chamber, an exhaust passage in said valve opening into the atmosphere, a duct leading from said valve toward the bottom of the cylinder, a poppet automatically operable in said first named valve to open its inlet port and close its exhaust passage for transmitting pressure through said duct, said duct opening into a supplemental valve having an opening leading into one end of said cylinder and an exhaust orifice open to the atmosphere, a closure member in said supplemental valve normally operated by pressure admitted through said duct to close said exhaust orifice and admit pressure into the end of said cylinder for maintaining said piston raised, and manually operable means for operating said poppet to close the inlet port in said first named valve and open its exhaust passage to release the pressure to the atmosphere whereby pressure above the valve closure in the supplemental valve is released to cause said closure to be actuated to open said exhaust orifice and relieve the pressure against the piston during its descent in said cylinder.

9. In a machine of the type indicated, a casing having a head with a pressure fluid reservoir at its upper end, a cylinder in the lower part of said head having an opening at the top exposed to the pressure in said reservoir, a piston reciprocable in said cylinder, said piston having a greater area on its under side than the area thereabove opposed to the force of the pressure fluid in said reservoir, a driver connected to said piston for reciprocation thereby, a valve in said casing having an inlet port opening from said pressure chamber in the head and an exhaust opening leading to the atmosphere, a duct connected to said valve and extending downwardly alongside said cylinder, said duct open at the bottom for communication with a supplemental valve, said supplemental valve having an exhaust orifice and an opening leading into the bottom of said cylinder, a valve closure slidably mounted in said supplemental valve, said valve closure adapted to seat across the exhaust orifice to close it and to be raised to open the exhaust orifice, a gasket of bifurcated crosssection held in a peripheral groove in said valve closure for engagement with the interior Wall of said supplemental valve, and manually operable means for actuating said poppet to close the inlet port in the first named valve and open the exhaust passage therefrom whereby pressure above said closure in the supplemental valve is exhausted through said first named valve to unseat said closure and open said exhaust orifice as the piston descends in said cylinder.

10. An apparatus of the type indicated comprising a reservoir for pressure fluid, a cylinder in communication with said reservoir, a piston slidable in said cylinder by said pressure fluid, said piston formed with its area opposed to pressure in said reservoir of less extent than the area on its opposite side to provide a dilferential relationship between potential forces for respectively moving said piston in opposite directions, a control valve having a port in communication With said reservoir and an exhaust orifice leading to the atmosphere, means for simultaneously opening said port and closing said exhaust orifice, a second valve connected to receive pressure fluid from said control valve, said second valve provided with a passage leading into one end of said cylinder and an exhaust orifice, and means operative by pressure fluid fed from said control valve to said second valve to close its exhaust orifice and open its passage into the end of the cylinder for returning the piston to first position after a driving stroke.

11. In combination, a reservoir for pressure fluid, a cylinder in communication with said reservoir, a piston reciprocable in said cylinder by said pressure fluid, said piston having a lesser area opposed to pressure in said reservoir than the area on its opposite side to provide a diflerential relationship between force potentials for respectively moving said piston in opposite directions, a control valve having a port for receiving pressure fluid from said reservoir and an exhaust orifice for venting such pressure to the atmosphere, means for closing said exhaust orifice and opening said port, a second valve connected to receive pressure fluid from said control valve, said second valve provided with a passage opening into one end of said cylinder and an exhaust orifice opening into the atmosphere, and means operative by pressure fluid fed from said control valve to close the exhaust orifice in said second valve and open the passage into the end of the cylinder for reversing the stroke of said piston.

2,101,159 Stevens Dec. 7, 1937 12 Clark May 6, Chilton Oct. 27, Julifs June 29, Julifs Aug. 31, Faccou Jan. 3, Chellis Aug. 13, Osborne Oct. 7, Doyle July 12,

FOREIGN PATENTS Great Britain Aug. 26,