US2989948A - Air powered stapling machine - Google Patents

Description

June 27, 1961 w. A. FoRREsTER 2,989,948

AIR POWERED STAPLING MACHINE June 27, 1961 W. A. FORRE'STER AIR POWERED STAPLING MACHINE 4 Sheets-Sheet 2 Filed July 7, 1954 June 27, 1961 w. A. FoRREsTER 2,989,948

AIR POWERED STAPLING MACHINE Filed July 7, 1954 4 Sheets-Sheet 3 June 27, 1961 Filed July 7, 1954 l l i?. m5 w) 7;0 d77 101 im. /g In. `I l 118 l 19 1 12,2 ,07 m3 78 l W02 .5. 77 I 75 19 l Il i l I i,

4 Sheets-Sheet 4 United States Patent O 2,989,948 AIR POWERED STAPLING MACHINE William A. Forrester, Herrin, lll., assguor to International Staple and Machine Company, Herrin, Ill., a corporation of Pennsylvania Filed July 7, 1954, Ser. No. 441,773 30 Claims. (Cl. 121-21) This invention relates to uid operated motors, and in particular is concerned with a stapling machine having an air powered, single cycle motor. The single cycle motor is adapted to be actuated -by a trigger which initiates the cycle and is thereafter rendered inoperative by means associated with the air motor so that continued depression of the trigger does not produce a repeating of the motor operation.

The air powered motor which is used in this stapling machine has been particularly provided with power operating means whereby it is enabled to operate a piston in a reciprocable manner. The piston drives a staple driving blade and retractible anvil in a retractible anvil type of stapling machine such as that disclosed in the Schafroth Patent No. 2,469,054, assigned to International Staple and Machine Company. These machines are designed to operate from a reciprocable driving force Iwhich drives the staple driving blade and coordinately also drives the retractible anvils. The retractible anvils are caused to rotate about a pivot point by suitable linkages in such a manner that when the staples are driven thereagainst they are clinched to hold together the material being stapled.

By means of this invention, there has been provided an air powered motor which is adapted to be used in a retractible anvil stapling machine of the type described or any stapling machine which utilizes a reciprocable driving and actuating force. A signal feature of this invention resides in the association of the trigger mechanism Iwith the air powered motor and the oper-ating means for the driving blade such that an entire cycle of operation may be completed by merely depressing the trigger. Thus, the trigger need not be -released to complete the staple driving operation and retraction and only one initiating or triggering operation is required. It is always possible that the operator may ybe negligent or careless in an operation requiring more than one manipulation of a machine, so there is no possibility of faulty operation due to the single actuation required in this device. Another feature of 4the invention is a Valving arrangement that forces the air motor piston to a retracted position and maintains it there, except when there is intentional operation of the valve mechanism.

There has further been provided in this invention means for adjusting the degree of penetration of the retractible anvil into the material to be stapled together. This has been accomplished by providing an adjustment screw which elevates the staple driving works with respect to the base of `the machine which rests upon the workpiece. This adjustment includes a threaded penetration control screw which may be adjusted without interfering with the operation of the air powered motor in any way and presents an easily accessible penetration control mechanism.

Accordingly, it is an object of this invention to provide a uid operated motor having a single cycle which may be initiated by a depression of a trigger to drive an operating member, and wherein the completion of the cycle and retraction is effected by the movement of the driven member.

It is a further object of this invention to provide an air powered motor for a stapling machine having a single cycle, and wherein the depression of a trigger completes the external -force required to effectuate the full single cycle operation.

Mice

It is still another object of this invention to provide an air powered motor having a main valve and a poppet valve for use with a stapling machine wherein the actuation of the main valve is effected by a trigger to drive an operating member, and wherein the stapling operation is completed by the movement of the operating member so as to return the main valve to its original position in dependent of the release ofthe trigger.

Yet a further object of this invention is to provide an air powered motor having a single cycle for use with a stapling machine in which the driving force is eit'ected through the opera-tion of a driving piston in such a manner that at the end of the driving cycle there is a reduction of power applied by the piston to prevent too great a driving force being furnished to the staple. This reduction of power at the end of the driving operation greatly reduces the possibility of breakage in the staple clinching operation.

Another object of this invention is to provide anair powered motor having a trigger and associated cam mechanism for initiating the action of the motor and means on the cam for completing the cycle of the motor independent of any further actuation or release of the trigger.

A further object of this invention is to provide a retractible lanvil stapling machine having a penetration control mechanism wherein the extent of penetration of the retractible anvils into the material being stapled can be varied by a control screw.

Still another object of this invention is to provide a retractable anvil stapling machine powered by a uid motor having a penetration control device adapted to vary the penetration of the anvils into the material being worked upon in such a manner that a control screw can be adjusted to vary the starting elevation of the anvils without effecting the length of stroke of an operating member actuated by said motor.

Yet a further object of this invention is to provide a single cycle motor actuated by a single 'applied control force in which there is means for varying the length of stroke of an operated piston.

Still another object of this invention is to provide a retractible anvile stapling machine having a pneumatic motor wherein the penetration of the retractible anvils may be varied by a control screw which varies the elevation of the motor and its operating member and the retractible anvils associated therewith.

Still another object of this invention is to provide an air powered retractible anvil stapling machine which can be completely operated to effect the entire stapling opertion Iby a single depression of the trigger in such a manner that it may be operated by unskilled workmen with no opportunity for jamming.

Further objects of this invention will appear in the detailed description which follows and will be further apparent to those skilled in the art.

For the purpose of illustration, two forms of air powered motors are disclosed in a schematic manner. Both of these vmotors are adapted to be used with stapling machines and a preferred embodiment is shown with a complete stapling machine for the purpose of description. It is to be understood that these drawings are for the purpose of illustration of this invention and that the invention is not limited thereto.

In the drawings:

FIG. 1 is a view in side elevation of the stapling machine;

F-IG. 2 is a view in front elevation of the machine;

FIG. 3 is a sectional view in elevation taken along the axis of the machine;

FIG. 4 is an enlarged view in section showing the main valve of FIG. 3;

FIG. 5 is a plan view in section taken on the line 5-5 of FIG. 2;

FIG. 6 is an enlarged view in plan section showing the poppet valve;

FIG. 7 is a plan view of the valve casting;

FIG. -8 is a sectional view taken on the line 8--8 of FIG. 7 showing the main Valve -and port arrangement;

FIG. 9 is a fragmentary view in vertical section showing the port arrangement to the piston cylinder;

FIG. 10 is a view in section taken on the -line 10--10 of FIG. 7 showing the poppet valveA housing;

FIG. 11 is a view in section taken on the line 11-11 of FIG. l showing the main valve port arrangement;

FIG. -12 is a schematic View showing a slightly modified air motor;

FIG. 13 is a schematic view showing a further modication of the air motor;

FIG. 14 is a pictorial view of the trigger;

FIG. l5 is a sectional view of the stapling machine taken on line 15-15 of FIG. l.

Reference will now be had to FIGS. 1, 2 and 3 wherein the stapling machine of this invention is generally indicated at 20. The machine includes las its main elements a base 21, a handle 22, and an air motor 23. Also, a trigger mechanism 24 and penetration control assembly 25 are shown in FIGS. l, 2 and 3.

The hase 21 is illustrated as a casting, having two generally L-shaped side pieces 26 which are connected together at the bottom by braces 27. This arrangement provides an elongated, channel-shaped base, within the interior of which channel is positioned a conventional staple feeding mechanism generally indicated at 28 which, per se, forms no part of this invention. The L-shaped base members 26 provide uprights 30 that, as shown especially in FIG. l5, spread laterally and forwardly, as well as upwardly, from the horizontal base elements. On their forward -faces the two side elements 30 of the base receive two guide strips 31 that are secured to the Side elements 30 by screws 33. The guide strips present inwardly turned edges that constitute tracks for a vertically movable staple driving assembly to be described.

A penetration control bar 34, for a purpose to appear, extends across the yforward faces of the two uprights 30. It is secured at its ends by screws 35 that pass through the guide strips 31 and into the uprights 30. A magazine retaining rod 36 (lower right of FIG. 3) extends between the side pieces 26 to overlie the forward end of a cartridge of staples and guide the same adjacent the driving blade.

A motor supporting frame or chassis 40 fits between the guides 31 on the uprights 30 of the base. Viewed from the front (see FIG. 2, wherein it so appears but must not be confused with the track strips 31. Compare FIG. 15), it is in the shape of an open rectangle, and its sides are provided with grooves 41 to engage the track strips 3.1 and to be retained by them. The grooves and strips enable the chassis 40 to be adjusted vertically on the strips. The chassis 40 is also provided with slots 42 in it vertical side portions, to receive the control bar 34 and permit the chassis to move vertically over the control bar. As will appear, the chassis 40 supports the air motor 23 and the handle 22, so that when it is adjusted upwardly and downwardly the air motor and also the handle 22 move with it.

The bottom wall of the chassis 40 has a threaded opening 43 within which a penetration control screw 44 is received. This penetration control screw 44 is provided with a knurled upper ange 45 and a bottom ange 46 spaced .therefrom a distance equal to -the width of the penetration control bar, which ts therebetween, as shown in FIGS. 2 and 3. A knurled and threaded lock nut 47 is provided to fit against the bottom wall of the chassis to lock the penetration control screw in position.

The air motor, as best shown in FIGS. l, 2, and particularly FIG. 3, is formed from an aluminum casting 50 mounted on the chassis 40 (and forming a lower cylinder head and a valve-receiving member), a cylinder 51, an upper cylinder head 52, and the handle 22. Screws 521 having their heads above the upper cylinder head 52, and passing downwardly through the lower cylinder head 50, are threaded into the chassis 4% (the front screws) and the handle 22 (the rear screws) to secure these parts together.

The cylinder contains a piston 53 connected to a piston rod 54 extending through a central opening in the casting 50. The piston rod is connected at its lower end to a drive block 55. A spring 56 is situated within an upper recess 57 in the valve casting so as to contact the bottom of the piston 53 when it approaches its lowermost position in the cylinder.

The actual stapling mechanism of the machine includes a flanged drive blade `64I connected to the bottom of the drive block 55 through blade spacing shims 59. These shims control the tightness of the staple clinch through the relative positioning of the bottom of the blade with respect to'the retractible anvils at the limit of the downward operation of the mechanism, as will appear. 'l'he blade is adapted to contact the head of a staple, as shown in FIG. 3. The retractible anvil mechanism and linkage of the machine are portrayed in FIGS. 2 and 3 where it is seen that two links 62 are connected at their tops by pivots 621 to the forward Aface of the drive block 55 and are connected at their bottom by pivots 622 to rotatable anvils 63. The anvils 63 are adapted to be pivoted about pins 64 which are supported in the lower part of the chassis or frame 40. 'Ihese anvils have anvil portions 65 projecting from their back faces, and which when extended, directly underlie the driving blade so that in the stapling operation a staple is driven by the blade against the anvil arms and clinched in a manner such as that disclosed in the Schafroth Patent No. 2,469,054, or otherwise as is conventional in this art.

A stroke control screw 69, shown in FIG. 3, is provided at the bottom of the drive block 55. This screw is adjustable and forms the part of the drive block that contacts a dog 142 on the cam 131 of the trigger, as will be later described.

The air motor 23 has as its main control elements a main valve 70 having a vertical axis and a poppet valve 71 having a horizontal axis, as is best shown in FIGS. 3 and 5, respectively. In order to control the operation of the main valve, and through it the air motor, a trigger mechanism 24, as shown in FIG. 3, is provided, which will be more fully described hereinbelow. All of these control elements are situated within and supported by the handle 22, the valve casting 50, and the cylinder 51 as a complete unit which is secured to the chassis 40 and is adapted to move with it relatively to the base 21.

Within th'e handle 22, shown in FIG. 3, is an inlet 72 which is adapted to be secured to a source of high pressure air of the order of 50 p.s.i. This inlet communicates with an inlet high pressure chamber 73, shown in FIG. 4, which includes a valve seat 74 formed at the bottom of the valve casting 50. A passage 75 leads from valve seat 74 to an opposing valve seat 76. On the other side of the valve seat 76 is an exhaust chamber 77 which is in communication with passage 78 that finally registers with two exhaust ports 79 that open to below the valve casting 50.

Another passage 82 leads from the passageway 75 into the bottom of the cylinder 51 beneath the piston 53, as best shown in FIG. ll.

The main valve 70 is of the twin valve type having an upper valve 83 and a lower valve 84 connected together by a valve rod 85, as best shown in FIG. 4. This valve has at its bottom an operating rod 86 which is adapted to be operated by the trigger mechanism. Proper sealing is effected by means of an O-ring 90 which seals the inlet chamber 73 against leakage to the outside past the operating rod 86.

A threaded cap 87 closes the top of the exhaust chamber 77 and has a central bore 88 to receive a valve guide pin 89. This provides for proper centering of the valve 70 when it is reciprocated in its operation. A valve spring 92 is seated within an annular recess 93 of the cap and bears against the upper side of valve 83 to maintain the valve in a normally unoperated position, shown in FIG. 4. In this position, the valve 83 is closed to exhaust against valve seat 76 and the valve 84 is opened to pressure with respect to the valve seat 74 so that the pressure port 82 conducts high pressure air from the inlet 72 to the bottom of the cylinder. It is evident that the two elements of the valve 70 can connect the bottom of the cylinder, by passage 82, alternately to pressure, when the valve 84 is open, or to exhaust when the valve 83 is open.

yThe secondary valve 71 has a similar operation with respect to the top of the cylinder. Its communicating ports are best shown in FIGS. 5, 6, 7, 10 and 1l. A pressure port 98, shown in FIG. ll, in the handle member 22 leads from pressure chamber 73 to a registering opening 100 in the valve casting 50 that opens into a poppet valve chamber 101 so that high pressure air is always in communication with some portion of this chamber. This chamber is closed at one end by an O-ring seal 102 which is prevented from popping out by a spring ring v103. The other end of the chamber 101 includes a valve seat 104 on the other side of which is a passage 105 leading to a valve seat 106.

At the other end of the valve casting 50 there is a poppet valve chamber 107 into which a portion of the exhaust passage 78 connects, so that the chamber 107 is always open to the exhaust ports 79. Situated medially of the valve 71 and communicating with the passage 105 is a port Y111 Iwhich passes up through a tube 112, shown in FIG. 9, exteriorly of the cylinder 5d, and continues through the upper cylinder head to the top of the piston 53. The upper and lower cylinder heads have lateral bosses between which the tube 112 is clamped.

In order to provide for communication of the outer part of the valve chamber 101 with the under side of the piston at the bottom of the cylinder, for a reason which will appear, the casting is provided with a port 113, as shown in FIGS. 7 and l0, which leads from the valve chamber 101 adjacent the sealing ring 102 to the cylinder 51 at bottom of the cylinder 51.

The valve 71, like the main valve 70, is also of the twin valve three-way type and has two valve members 115 and 116 cooperating with the valve seats 104 and 106, respectively. A valve rod 117 joins the two valves and is of a smaller diameter than passage 105 in order to provide for communication and passage of air therethrough. T'he valve member 115 of the poppet valve 71 is connected at its top to a valve piston 118 which is provided with an -ring seal 119 so as to divide the Valve chamber 101 into two compartments, the top part of which, in FIGS. 5, 6 and 7, constitutes a pressure chamber for operation of the valve piston f1-18.

The other end of the valve 71 has a spring 121 bearing against the exterior of valve member 116 at one end, and against a plate 122 at its other end. The plate 122 is held in the valve chamber 107 by a spring ring retainer 123. The spring 121 is -a compression spring and biases the valve 71 upwardly in opposition to the position shown in FIGS. 5 and 6. The position shown, however, is the normal position when the main valve 70 is in the unoperated position of FIG. 3.

It may be seen that the upper end of the cylinder 51 is alternately connected to pressure or exhaust by the valve 71. When that valve is as shown in FIGS. 5 and 6 the `top of the cylinder is exhausted, because the passage 1-11 is connected around the valve 116 to the exhausts 79; and, at the same time, the high pressure is cut off from the top of the cylinder. This condition continues so long as the pressure in the bottom of the cylinder 51 is high enough to act on the valve piston 118, via the passage 113, and force the valve down against the spring 121. 'Upon relief of pressure in the bottom of the cylinder, and in the valve pressure chamber, the spring 121 forces the valve 71 up in FIGS. 5 and 6, to close oi the exhaust and to admit high pressure to the top of the cylinder 51.

The trigger mechanism 24 which is used with the air motor is particularly shown in FIGS. 3 and 14. This trigger mechanism has as its component parts a trigger and a cam 13i1. 'Ihe trigger 130 has opposed side pieces 132 disposed in vertical relationship and connected together by a horizontal brace 133. The side pieces are pivoted about a pin 134 which is fitted within bifurcated portions 135 depending from the handle 22. A coil spring having two arms 136 and 137 is mounted around the pin 134 in such a manner that the arm 136 bears against the lower portion of the handle 2l2, and the arm 137 bears against the brace 133 to urge the spring to the unoperated position shown in FIG. 3.

The cam 131 is pivoted about a cam pin 140 connected between the trigger side pieces l132 so that the cam is in pivotable relation with respect to the trigger. The cam is biased in a counterclockwise manner (as the parts appear inFIG. 3) with respect to the trigger by a spring 141 which is connected at its lower end to a stud on the brace 133. The cam 131 is held in the biased position shown in FIG. 3 so that it bears against .the pin 134 in contacting relationship therewith through a dog 142.

The cam 131, besides being provided with dog 142, has an upper cam surface 143 which is contiguous with a vertical scar surface 144. The positional relationship is such that in the normal unoperated position the cam surface 143 is immediately below the valve operating member 86.

A diagrammatic illustration of the foregoing -air motor which 'may be used with the stapling machine 20, slightly modified for clarity of illustration, is shown in FIG. 12 and is generally indicated at 150. This air motor includes a valve casing 151 connected to the bottom of a cylinder 152 closed at the top by a cylinder head 153. Situated within the cylinder is a piston 154 connected to a piston operating rod 155.

The valve casing 151 includes a high pressure inlet 156 opening into a high pressure valve chamber 157. This valve chamber is in communication through a passage 158 with a poppet valve chamber 159.

A valve seat 161 is adapted to connect the valve chamber 157 with a passage 162 which is in communication through port 163 with .the cylinder 152 at the bottom side of the piston 154. The other end of the passage 162 is in communication with the Valve seat 164 opening into an exhaust chamber 165. The exhaust chamber 165 is connected to an exhaust port 166.

A main valve has valve members 171 and 172 connected together by a valve rod in such a manner that the valves cooperate, respectively, with valve seats 161 and 164. This valve is biased to the position shown in FIG. 12 by a spring 173 bearing at one end against a valve member v164 and at its other end against a piston cap 174. The lower end of the valve 170 has an operating rod which will be more fully described hereinbelow.

A poppet valve 1-80 is shown at the right hand side of FIG. l2 and is of the twin Valve piston operated type. The poppet valve chamber 159 is provided with a bore 181 for receiving the piston of the poppet valve and has an upper opening 182 in communication with the cylinder 152 at the bottom side of Ithe piston. A bleed port 183 is in communication with the bottom of the opening 182.

At the lower side of the poppet valve passage 159 is a valve seat 184 forming one end of a passage 185 which has at its other end a second valve seat 186. A port I187 medially connects the passage 185 with the cylinder 152 at the top side of the piston.

'I'he poppet valve 180 has its twin valve members 190 and 191 adapted to cooperate with valve seats 184 and 186, respectively, through a valve rod which connects these valve members and extends upwardly of the valve member 184 to be iixedly connected to a piston 192. 'I'he valve seat 186 communicates with an exhaust chamber 193 (open to atmosphere) within which is supported a poppet valve spring 194 secured at its bottom end by a washer within the chamber.

Returning to the main valve 170 of the modiication in FIG. 12, it will be seen that the operating member 175 is provided with a detent groove 195. An operating handle l196 has detent balls 197 which are biased against the groove 195 by springs 198 so as to hold the handle 196 in the axial position with respect to the operating member 175, as shown in FIG. 12. However, a force may be applied to cause the balls 197 to ride out of the groove and change the axial relationship of the handlel with respect to the operating rod.

' It is quite -apparent that the connections and operations of the main valve 170 and the poppet valve 180 correspond to the connections and operations of the valves 70 and 7.1 previously described. The main valve 170 is operated by the detented handle 196 and the cap 174 instead of by the trigger arrangement, as wil-l appear.

In FIG. 13 is shown another modification of an air motor generally indicated at 200 wherein a valve housing 201 is situated exteriorly as a separate unit from a cylinder 202. The cylinder 202 contains a conventional piston '203 and piston rod 204 that may be used for actuating a crosshead and associated stapling parts, such as illustrated in FIGS. 1-11.

The valve housing 201 contains a high pressure inlet 205 which constantly communicates with a poppet valve chamber 206 and -a main valve chamber 207. EIn this modification the poppet valve is indicated generally at 208, and the main valve is indicated at 209. In the valve chamber 207 there is a lower valve seat 211 which leads into a valve passage 21i2. This valve passage 212 is in communication through a port 213 with the cylinder at the lower side of the piston. The valve passage 212 is also in communication through a port 214 with a poppet valve piston chamber 215. At the other end of the valve passage 2.12 is a valve seat 216 which is in communication with an exhaust chamber 217 and exhaust port '218.

The poppet valve chamber 206 previously described is provided with a valve seat 220 spaced from another poppet valve seat 221 by an intermediate valve passage 222 which is in communication with the top of the cylinder by a passage 2,23.

The main valve 209 is of the twin valve three-way type having an upper valve vmember 230 and a lower valve member 231 connected by an operating rod 232 which extends slidably through the valve housing to a solenoid coil 233. Biasing the valve 209 in such a manner that the valve 230 is normally closed against the valve seat 216, is a spring 234. The lower end of the valve 207 may be slidably sealed in the valve chamber with atmospheric pressure on the lower side. The poppet valve 208 is also of the twin valve threeway type having an upper Valve member 240 and a lower valve member 241 which is connected to a piston 242. This valve is provided with a valve spring 243 for biasing the poppet valve toward a reverse position to that shown in FIG. 13 when the main valve is operated.

The soft iron core of the solenoid includes the detent support 245 having spring-urged detent balls 246 engageable in a groove around the valve rod 232. Movement of the core by energization of the coil 233 lifts the detent balls and the valve rod when the balls are in the groove. The operating rod is provided with =a ange 247 upon which a valve return arm 24S may engage. One end of the arm 248 is pivoted to the supporting frame of the solenoid and the other end projects toward-the cylinder to be contacted by an adjustable contact nut 249 situated Operation It may be convenient to describe the operation of the machine by first referring to the diagrammatic showing o-f FIG. l2.

In the modified motor shown in FIG. l2, the air motor 150, like the motor 23, is adapted to be used with the identical stapling machine 20 or in conventional stapling machines having a fixed anvil as well as in other applications.

In the air motor 150, the main valve is maintained in the normally unoperated position shown, by the force of spring 173. This spring keeps the valve member 171 closed against its valve seat 164 and the valve member 172 open with respect to its valve seat 161. In this condition, high pressure air enters through inlet 156 and passes through the passageway 162 and the port 163 to the bottom of the cylinder below the piston. Simultaneously therewith, high pressure air is admitted to the top ofthe valve piston 192 in the chamber 182. The similarity of this to the principal drawings should be evident, and will be clear from the detailed description thereof, later given.

High pressure air above the piston 192 causes the poppet Valve to be maintained in the position shown in FIG. 12 such that the valve member 190- is closed against its valve seat 134, and the valve 191 is opened with respect to its valve seat 186. This connects the top of the cylinder to exhaust by the passages 187, 185, and 193. Accordingly, since the high pressure air ows to the bottom of the piston cylinder 152 and the top of the piston is open through the passage 187 to exhaust through the valve 191, the piston is kept in the raised position.

The motor is adapted to be operated by pushing upwardly on the operating handle 196 so that the valve 172 closes the flow of high pressure air through port 163 to the bottom of the piston. As this occurs, the valve member 171 is opened and the port 163 is thereby connected into the exhaust `chamber 165 and the exhaust port 166. As the pressure beneath the piston is reduced (also reducing pressure -above the valve piston 192), high pressure air passes through the conduit 158 to the piston 192 about its annular area through a loose fit with the bore 181. This applied force, together with the biasing action of the spring 194, pops the poppet valve up to open the valve member and close the valve member 191. Therefore, the high pressure air in the passage 158 passes through the valve member 190 and the passage 185, and upwardly through the passage 187 to the top of the piston 154.

Under this applied force at the top of the piston, the piston and piston rod will move downwardly until the bottom of the piston contacts the top of the piston cap 174, As this occurs, the piston cap moves downwardly also a limited amount until it pushes against the top of the valve rod 175. As the valve rod 175 is pushed downwardly, it will ride out of engagement with the detent balls 197 which are urged against their biasing springs 198 in such a manner that the groove 195 permits axial displacement. Thus, even if the operating handle is held up, the main valve and poppet valve will return to the original position shown in FIG. 12 to complete the cycle and return the piston 154 to .the'upward position.

After this has occurred, the operating handle 196 must be returned to the position shown in FIG. 12 to ready it for a new cycle and another `operation of the air motor. Thus, there has been provided in this motor a complete single cycle operation lwhich provides a safety feature against continued cycling, `and does not depend upon release of the handle or trigger element to stop the motor.

The foregoing explanation of FIG. 12 gives the general operation of the motor, wherein the main valve initiates the reversals, and the secondary valve responds to cylinder-bottom pressure conditions. The operation of the principal drawings will now be described.

The stapling machine in its unoperated position, shown in FIGS. 3, 4, 5, 6 and 7, has its piston maintained in the elevated position by a combination of actions. Thus, the main valve 70 is kept in the position shown in FIG. 3 by the force of spring 92 and by static air pressure which closes valve 83 against valve seat 76 and opens valve 84 to valve seat 74. The poppet valve 71 in FIGS. 5 and 6 is maintained in -its position by the application of air pressure rather than spring pressure.

To explain more fully, high pressure air enters the handle 22 (as from a flexible hose connected to a source of high pressure air) through the inlet 72, and then passes through the valve 84, shown in FIGS. 3 and 4, into the passage 75 and through the port 82, shown in FIGS. 8 and ll, to the bottom of the cylinder. This establishes a region of high pressure in the bottom of the cylinder. At this time the poppet valve 71 is in the position of FIGS. 5 and 6, because cylinder-bottom pressure acts by the passage 113 into the pressure chamber of the valve piston 118 to drive the valve against the force of the spring 121. The top of the cylinder is in communication (FIGS. 5, 6 and 9), by the port 111, through the passage 105, the valve seat 106, the valve chamber 107, and the passage 7S, with the exhaust passage 79. Hence because of high pressure below it and exhaust pressure above it, the piston is maintained in this raised position. The poppet valve 71 is kept in the position shown in FIG. 5, so long as the high pressure remains in the bottom of the cylinder 51, or, in other words, until the main valve 70 is shifted to its upper position. It will be noted that the lower side of the piston 118 is also under a high pressure condition through port 100 and passage 98 which lead to chamber 73 which is under the same high pressure as that at the bottom of the cylinder, but since there is a restricted annular area on the lower side of the piston as contrasted with the upper side, this force and the spring 121 are overriden by high pressure acting on the entire outer surface of the piston 118. Thus, the valve 115 is urged against valve seat 104, and conversely the valve 116 is kept open with respect to its valve seat 106.

The stapling machine can be operated by actuating the trigger mechanism 24 by placing a finger under the brace or transverse part 133 and rocking the trigger 130 in a clockwise manner about the pivot 134. When this is effected, the cam surfaced 143 of the cam 131 rides under the bottom of the main valve operating member 86, and elevates the valve 70 to close the valve 84 and open the valve 83. It will be noted that the cam member cannot give or further rotate counterclockwise about its pivot since the dog 142 contacts the underside of the pin 134; and it cannot rotate clockwise since the cam pivot 140 is to the right (in FIG. 3) of the valve rod 86, and thus there is a iirm (though sliding) contact with the bottom of the operating member. The spring 141 aids in holding the cam 131 against clockwise movement about its pivot 140.

As the main valve 70 moves upwardly, it closes its valve member 84 against the valve seat 74 and thus cuts ott high pressure through the port 82 to the bottom of the cylinder and piston. As this occurs, simultaneously the valve member 83 is opened away from its valve seat 76 so that the port 82 is opened to exhaust chamber 77 and therethrough to the passage 78 and the exhaust ports 79, which establishes a region of low pressure or exhaust beneath the piston. This region of low pressure is then simultaneously established through the port 113 to the exterior of the poppet valve piston 118.

Under this situation, the lower side of the piston 118 of the poppet valve 71 in the annular area is under high pressure through the passage 100 communicating with the high pressure chamber 73, and this causes the poppet valve 71, under the combined action of the differential air pressure and spring 121, to reverse the valve posi- 10 tion. Thus, the valve member 115 is opened from its valve seat 104 and the valve member 116 is closed against the valve seat 106. Therefore, high pressure can pass from the passage 100 through the inside of the valve chamber 101, through the passage 105 and the passage 111, to the top of the piston through the cylinder head. The reversal of the pressure condition upon the piston, whereby a high pressure is established at the top of the piston, thus causes the piston to move downwardly with great force and to effectuate the stapling operation.

When the piston 53 is caused to move downwardly, the piston rod 54 is driven thereby. After accelerating to a substantial speed, the piston drives the driving blade against a staple, to hammer the staple'legs downwardly through the material being stapled. At the same time, the descending driving block or crosshead 55 lowers the pins 621 at the top of the links 62, thereby spreading the pivots 622 that join the links 62 with the tops of the anvil arms 63. This drives the pointed anvils 65 through the material in an arcuate manner in the direction of the indicated arrows. This causes a penetration of the rotary anvils into the material being stapled so that the staple is driven thereagainst and clinched in the usual manner in this type of stapling action.

As the piston is driven downwardly, it comes to a point where just prior to the end of its downward movement it contacts the upper end of the spring 56. This cushions the applied force to the driving blade 60 and the links 62. This cushioning prevents overclinching and breaking of staples and anvils through too great an application of power, and is a safety feature of this invention.

Also, as the piston 53 is lowered, the control screw 69 which is attached to the bottom of the driving block 55, as shown in FIG. 3, will contact the dog 142 of the cam. This contact causes the cam to rotate in a clockwise fashion about its pivot pin against the biasing action of the spring 141 in such a manner that the cam surface 143 rides oli the bottom of the valve operating member 86. When this occurs, the valve is no longer upwardly opposed against the force of the return spring 92, and, accordingly, the valve is returned to the position shown in FIG. 3, This reestablishes the region of high pressure through valve 84 into port 82 to the bottom of the piston, which returns the poppet valve 71 to the illustrated position. The return of the two valves 70 and 71 causes a return of the piston to the upward position to complete the stapling cycle. The return of the piston and its piston rod 54 similarly withdraws the driving blade 60 and the links which operate the rotary anvils.

It will be noted that at the end of this operation, after the piston has returned to its original position, if the trigger is still held in operated position, the cam 131 is prevented from returning to the position shown in FIG. 3 by the contacting of the vertical sear surface 144 with the side of the valve operating member adjacent its end.

55 This prevents a new operation of the main valve 70 since the cam surface 143 is held out of contact with the operating rod 86. Thus, a continued cycling is prevented from occurring. This is normally to be avoided, since obviously a repeated stapling operation over the same spot would be undesirable. However, it is contemplated that under appropriate -circumstances where either the stapling machine is moved or the workpiece is moved, the vertical sear 144 may be removed so that a continued operation of the trigger would return the cam surface 143 to the bottom of the operating member and cause a repeated cycling operation of the air motor.

Where it is desired to adjust the limits of eiective stroke of the driving blade 60, the drive block control screw 69 may be adjusted toward or away from the block. This will reduce the distance between the head of the screw and the dog 142, or increase the distance and, accordingly, the length of stroke, depending on whether the screw is screwed into or out of the block.

Where it is desired to vary the degree of penetration of the rotary anvils into the material being worked upon,

the penetration control nut 45 may be operated. First the lock nut 47 is loosened. Then, since the nut 45 has a right hand thread, a clockwise movement Of the nut will cause the chassis 41) to be elevated on the track or guides 31 relative to the base or frame 21. This Will raise the handle and power mechanism of the stapling mechanism above the base of the machine. Consequent- 1y, the penetration of the anvils below the bottom of the base will be lessened. Conversely, a greater penetration can be efectuated by a counterclockwise movement of the nut 45, The penetration bar allows relative movement of the housing 40 with respect to it by virtue of the slots 42 in the housing through which the control bar passes at its ends adjacent its connection to the base.

yIn the modification of FIG. 13, there is shown the air motor generally indicated at 200 in which the valve housing 201 may be situated entirely exteriorly of the cylinder 202. This permits easy maintenance and replacement of parts, as well as providing for a simplified construction. In this embodiment of the invention, the main valve 209 is kept in the normally unope'rated position shown in FIG. 13 by the biasing action of spring 234 and the application of pressure against the inside of valve 231. This seats the valve member 23@ against its valve seat 216 and opens valve member 231 with respect to its valve seat 2.11.v The main Valve then allows high pressure from the inlet 205A to be passed by port 213 into the bottom of the cylinder 202 underneath the piston 203. Under this condition, high pressure air likewise flows past the valve member 231 to the passage 214 te be admitted to the bottom of the piston 242 in piston chamber 215. Pressure therein causes the upward seating of the valve 208 so that its valve member 241 is seated against its valve seat 220. This opens the valve member 240 with respect to its Valve seat 221, which is in communication through the passage 223 with the top of the piston. Therefore, since the valve 240 is open to the exhaust chamber 217, the top of the piston is exhausted through the exhaust port 218 and the piston is maintained in its upward position shown in FIG. 13.

The air motor 200 is adapted to be operated by energization of the solenoid 223. When this occurs the detent mechanism 245 is pulled upwardly by magnetic force, and with it the valve rod is also moved upwardly against the force of the spring 234. The detent force is greater than the force of the spring 234. When the foregoing occurs, the valve member 231 of the main Valve 209 is closed so that high pressure air no longer is admitted to the bottom of the piston 203 nor to the bottom of piston 242. Simultaneously, the valve member 216 is opened so that both the bottom side of the power piston 203 and the valve piston 242 are opened through the valve 230 into the exhaust chamber 217 and out exhaust port 218.

As this occurs, the combined force of the poppet valve spring 243 and the high pressure through inlet 205 acting on the annular area of the valve piston 242 pops open the poppet valve 208. This opens valve member 241 to the oW of high pressure air into the passageway 222 and closes the valve member 240 against its valve seat 221. Thus, high pressure air will flow through passage 222 and upwardly in passage 223 to the top of the power pisto-n 203 and cause it to move downwardly.

As the piston 203 moves downwardly, it carries with it the standard 250 until the adjustable contacting nut 249 contacts the freely pivoted arm 248. When this occurs, the arm 248 is forced against the flange 247 on the main valve rod and overrides the ball detent mechanism biasing force so that the valve rod moves downwardly with respect to said detent balls 246. Thus, the contacting nut 249 causes the valve rod to return the valve 209 to its original position in which it is maintained by high pressure air' and the return spring 234. Continued energization of the solenoid no longer effects the operation of the motor. The solenoid `must be deenergized to permit the recoupling of the detent mechanism 245 with the valve rod,

12 after which the above described operation may be repeated.

Either one of the described modifications of the air motors 150 and 200 may be utilized with the stapling machine 20 or any other type of stapling machine. It is further apparent that either one of these air motors or air motor 23 may be used in other applications where a single cycle motor is desired. These motors are of particular advantage where it is desired to have a complete reciprocating cycle of a piston operating member which is 'effectuated by only a single control force. Thus, the control force need only be initiated and its reversal is not needed to complete the cycle. This feature is of great advantage in many operations, as will be apparent to those skilled in the art, since the control force need not be gauged or timed for successful consummation of the cycling operation.

Various changes and modifications of this invention may lbe made in addition to those above described, as will be apparent to those skilled in the art. Such changes and modifications will Abe within the teachings of this invention, as defined by the scope of therclaims appended hereto.

What is claimed is: y

1. In ya'staple machine having a piston, piston rod and a connected staple driving blade, the improvement comprising a fluid operated motor for driving the piston rod connected with said driving blade means, including a trigger cooperating with a valve for actuating said motor and moving said piston rod through a staple driving operation, motor reversing means adapted to cooperate with said piston rod at the end of the staple driving cycle to reverse the `direction of operation of said piston rod and return the driving blade to complete a full cycle, said last named means including a cam connected with said trigger, and having means cooperating with said piston rod at the end of the blade driving operation to reverse the direction of said piston rod.

2. In a staple machine having a piston, a piston rod and a connected staple driving blade, the improvement comprising a fluid operated motor for driving the piston rod connected with said driving blade, said motor having a main valve movable between first and second limiting positions, a poppet valve movable between third and fourth limiting positions responsive to changes in fluid pressure determined by the position of said main valve, trigger means for moving said main valve from said rst position to said second position to actuate said motor through a staple driving operation, and means operatively associated with said piston rod for completing the cycle of said driving blade by returning it independently of continued actuation of Vsaid trigger.

3. In a staple machine having a staple driving element, a fluid motor for driving the element, valve mechanism for controlling the motor, said valve mechanism having manually movable means to operate the motor in a driving direction to drive the element and said valve mechanism lbeing returnable to reverse the motor to return the element to starting position, yieldable connections between the manually movable means and valve mechanism, means operated by the motor upon movement to driving position to overcome the yieldable connections and return the valve mechanism, despite retention of the movable means in its valve-displacing position.

4. In a staple machine having a piston, piston rod and a connected staple driving blade, the improvement comprising a fluid operated motor for driving the piston rod connected with said driving blade, said motor having a main valve movable between first and second limiting positions, a poppet valve movable between third and fourth limiting positions responsive to the position of said main valve, trigger means for moving said main valve from said first position to said second position to actuate said motor through a staple driving operation, means operatively associated with said piston rod for completing the cycle of said driving blade by returning it independently of continued actuation of said trigger, said last named means being adapted to cooperate with said piston rod at the end of the staple driving operation and return said main valve to the iirst position independently of continued operation of said trigger, said means further including a cam having means thereon for moving said main valve to its second position when the trigger is depressed, and means for disengaging the trigger action independently of continued operation through disengagement of the cam with said main valve for returning said main valve to its first position.

5. In a staple machine having a piston, piston rod and a connected staple driving blade, the improvement comprising a uid operated motor for driving the piston rod connected with said driving blade, trigger means iucluding a trigger for actuating said motor through a staple driving operation, means operatively associated with said piston rod for completing the cycle of said driving blade by returning it independently of continued actuation of said trigger, and means for varying the distance of the stroke through which said piston rod operates.

6. In a staple machine having a piston, piston rod and a connected staple driving blade, the improvement comprising a fluid operated motor vfor driving the piston rod connected with the driving blade, motor actuating means for actuating said motor and piston rod through a staple driving operation, and motor reversing means adapted to cooperate With said piston rod at the end of the staple driving cycle to reverse the direction of operation of said piston rod and return the driving blade to complete a full cycle, said last named means including biased detent means in said motor actuating means cooperating with said piston rod at the end of the blade driving operation to disengage the motor actuating means and return the piston rod to its original position.

7. In a staple machine having a piston, piston rod and a connected staple driving blade, the improvement comprising a fluid operated motor for driving the piston rod connected with the driving blade, motor actuating means for actuating said motor, said motor having a main valve movable between first and second limiting positions, a poppet valve movable between third and fourth limiting positions responsive to the position of said main valve, said motor actuating means being adapted to move said main valve from said first position to said second position to actuate said motor throught a staple driving operation, and means operatively associated with said piston rod for completing the cycle of said driving blade by returning it independently of continued actuation of said trigger, said last named means being adapted to cooperate with said piston rod at the end of the staple driving operation and return said main valve to the first position independently of continued operation of said motor actuating means, and including a piston adapted to operate said main valve to its first position.

8. In a staple machine having a piston, piston rod and a connected staple driving blade, the improvement comprising a uid operated motor for driving the piston rod connected with the driving blade, motor actuating means for actuating said motor and piston rod through a staple driving operation, motor reversing means adapted to cooperate with said piston rod at the end of the staple driving cycle to reverse the direction of operation of said piston rod and return the driving blade to complete a full cycle, said last named means including biased detent means in said motor actuating means operatively cooperating with said piston rod at the end of the blade driving operation to disengage the motor actuating means and return the piston rod to its original position, said motor actuating means further including a solenoid which is adapted to attract said detent means upwardly, and an operating rod biasedly held by said detent means.

9. In a staple machine having a piston, piston rod and a connected staple driving blade, the improvement das comprising a fiuid operated motor for driving the piston rod connected with the driving blade, motor actuating means for actuating said motor, said motor havinga main valve movable between first and second limiting positions, a poppet valve movable between third and fourth limiting positions responsive to the position of said main valve, said motor actuating means being adapted to move said main valve from said first position to said second position to actuate said motor through a staple driving operation, means operatively associated with said piston rod for completing the cycle of said driving blade by returning it independently of continued actuation of said trigger, said last named means being adapted to cooperate with said piston rod at the end of the staple driving operation and return said main valve to the first position independently of continued operation of said motor actuating means, said motor actuating means further including a solenoid which is adapted to attract said detent means upwardly, and an operating rod biasedly held by said detent means, and said motor reversing means including a movable contact element carried by said piston rod, which element is adapted to contact said operating rod at the end of the staple driving operation lto return said main valve against the force of the detent and said solenoid to its first position.

10. A uid operated motor having a piston rod and a piston, said motor having trigger means including a trigger for actuating said motor and piston rod through a driving operation, motor reversing means adapted to cooperate With said piston rod at the end of the driving cycle to reverse the direction of operation of said piston rod and return the motor to complete a full cycle, said last named means including a cam operatively associated with said trigger, and said cam having means cooperating with said piston rod at the end of the driving operation to reverse the direction of said piston rod.

l1. A fluid operated motor having a piston rod and a piston, said motor having a main valve movable between first and second limiting positions, a poppet valve movable between third and fourth limiting positions responsive to changes in uid pressure determined by the position of said main valve, trigger means for moving said main valve from said firstV position to said second position to actuate said motor through a driving operation, means operatively associated with said piston rod for completing the cycle of said driving operation by returning it independently of continued actuation of said trigger, said last named means being adapted to cooperate with said piston rod at the end of the driving operation and return said main valve to the first position independently of continued operation of said trigger, said means further including a cam having means thereon for moving said main valve to its second position when the trigger is depressed, and means for disengaging the trigger action independently of continued operation for returning said main valve to its lirst position.

12. A uid operated motor having a piston rod and a piston, said motor having trigger means including a trigger for actuating said motor through a driving operation, means operatively associated with said piston rod for completing the cycle of said driving operation by returning said piston rod at the end of its drawing stroke independently of continued actuation of said trigger, and means for varying the distance of the stroke through which said piston rod operates.

13. A uid operated motor having a piston rod and a piston, said motor having means for actuating said motor and piston rod through a driving operation, and motor reversing means adapted to cooperate with said piston rod at the end of the driving cycle to reverse the direction of operation of said piston rod to complete a full cycle, said last named means including biased detent means in said motor actuating means operatively cooperating with said piston rod at the end of the driving operation to disengage the motor actuating means and return the piston rod to its original position.

14. A iiuid operated motor having a piston rod and a piston, said motor having means for actuating said motor and piston rod through a driving operation, motor reversing means adapted to cooperate with said piston rod at the end of the driving cycle to reverse the direction of operation of said piston rod and return the piston rod to complete a full cycle, said last named means including biased detent means in said motor actuating means cooperating with said piston rod at the end of the driving operation to disengage the motor actuating means and return the piston rod to its original position, said motor actuating means further including a solenoid which is adapted to attract said detent means upwardly, and an operating rod biasedly held by said detent means.

15. A iiuid operated motor having a piston rod and a piston for actuating said motor, said motor having a main valve movable between rst and second limiting positions, a poppet valve movable between third and fourth limiting positions responsive to the position of said main valve, said motor actuating means being adapted to move said main valve from said rst position to said second position to actuate said motor through a driving operation, means operatively associated with said piston rod for completing the cycle of said power means by returning it independently of continuedV actuation of said trigger, saidV last named means being adapted to cooperate with said piston rod at the end of the driving operation and return said main valve to the first position independently of continued operation of said motor actuating means, said motor actuatingV means further including a solenoid which is adapted to attract said detent means upwardly, and an operating rod biasedly held by said detent means, and said motor reversing means including a movable contact element carried by said piston rod, which element is adapted to contact said operating rod at'the end of the driving operation to return said main valve against the force of the detent and said solenoid to its first position.

16. In a machine of the kind described: a cylinder and a piston reciprocable between first and second ends of the cylinder; a valve device having a dual valve movable to a iirst position wherein it connects the second end of the cylinder to a high pressure fluid passage, and movable to a'second position wherein it connects the second end of the cylinder to exhaust; means to move the valve, including a yieldable means urging it toward its iirst position to port high pressure fluid, and a uid pressureresponsive wall connected to the valve to move it to its second position to port the second end of the cylinder toV exhaust; the pressure-responsive wall being subjected to iiuid pressures corresponding to those in the first end of the cylinder, the yieldable means having a force to displace the valve Vagainst exhaust pressures on the wall, but yieldable to pressures on the wall corresponding to piston-moving pressures in the iirst end of the cylinder; and means to connect the irst end of the cylinder to the high pressure fluid passage and to exhaust.

17. In a iluid motor: a cylinder, a piston reciprocable Vin the cylinder; and valve mechanism for controlling admission and emaust of iiuid lto the opposite ends of the cylinder, the mechanism including a main valve and a secondary valve; lthe main Valve being oppositely movable to a first position wherein it ports one end of the cylinder to a high pressure inlet, and to a second position wherein it ports the Isame one end of the cylinder to exhaust; the secondary valve being also oppositely movable to -a first position wherein it ports the other end of the cylinder to exhaust, and to a second position wherein it ports the said other end of the cylinder to the high ypressure inlet; means to move the secondary valve from its second position -to its first position, including a iuid pressure-responsive device connected to operate the valve, and having passage means connected to subject it to fluid pressure conditions corresponding to those in the said one end of the cylinder so that when the fluid pressure conditions in the said one end of the cylinder are high, the valve will be moved to its iirst position; and yieldable means to urge the secondary valve into its second position when fluid pressure conditions in the said one end of the cylinder are low.

18. The fluid motor of claim 17, wherein the main valve has yieldable means normally urging it into its rst position; and means to displace it to its second position.

19. The fluid motor of claim 18, wherein the last- Vnamed displacing means includes a device displaceable to move the main valve into its second position, said device having a relasable connection with the valve; and means operable by the piston as it reaches its second position to cause release of the connection and return of the main valve to its rst position under action of the yieldable means.

20. The motor of claim 19, wherein the displaceable device includes a trigger, a cam movable by the trigger and adapted to engage the main valve -to displace it, the releasable connection comprisinga movable mounting ,for the cam whereby it may move relatively to the trigger,

away from the valve; and the means operable by the piston lincluding a part on the piston engageable with a part on the cam to move the latter away from the valve.

2l. The motor of claim 18, wherein the displacing means comprises a. power device, a releasable connection between the power device and the main valve, the connection providing for movement of lthe valve upon operation of the power device, but being releasable to enable the valve to be moved independently from the power device.

22. The mechanism of claim 20, wherein the cylinder includes two cylinder heads and a cylindrical element between them; one of the cylinder Vheads having two cylindrical passages therein, and the two valves being reciprocably mounted for valving movements in the cylindrical passages.

23. The mechanism of claim 19', wherein there is a base and a chassis; the cylinder, piston and valves being securely mounted on the chassis; and a handle also securely mounted on the chassis, the device displaceable to move the main valve comprising a trigger mounted on the handle so that the piston may-be caused to operate by a user holding the machine by the handle and operating the trigger.

24. The mechanism of claim 23 wherein the chassis is adjustably mounted on the base so that the end position of operation of the piston, relatively to the base, is adjustable.

25. The mechanism of claim 23, wherein there are driving means connected to the piston for driving objects supported on the base to positions determined by the extreme position of .the piston relatively to the base, and means to adjust the position of the chassis relatively to the base, to thereby adjust the extreme driven position of the piston, and of the object driven thereby.

26. The combination of claim 25, wherein the base includes pants engageable ito rest upon a surface, and upright parts, the chassis including a chassis part mounted slidablfy upon the upright parts of the base; displacement means interengageable between the base and chassis movaible to displace the chassis slidably on the base, and means to secure the chassis against further such movement.

27. The combination of claim 23, wherein the base includes an elongated horizontal portion engageable -to rest upon a surface, and upright parts at one end thereof, the chassis being attached to the upright parts, and the handle extending back over the horizontal portion of the base, and the cylinder being mounted with its piston rod movable between the upright parts of the base and the handle.

28. In a machine of the kind described, a base having a Work-engaging surface, a chassis, a cylinder yand piston therein, Valve means for controlling operation of the piston, mechanism to operate the valve means, and a handle, the chassis, cylinder, valve means, the mechanism to operate the valve means, and handle all being connected together into a subassembly that is adjustably mounted on the base; and means to adjust the subassembly on the base ltoward and from the Work-engaging surface.

29. 'I'he machine of claim 28, wherein the piston moves toward and from the Work-engaging surface and has a piston rod and article-driving means connected to it, and means on lthe base to hold articles tobe disposed in the path of the driving means.

30. The combination of claim 28, wherein the piston has article-driving means and article-receiving means connected to it to be driven by piston movement toward the work-engaging surface; the base having upright parts extending perpendicularly to the Work-engaging surface, upon which vthe chassis is mounted, the article-driving and article-receiving means being mounted behind the chassis, and the handle projecting generally parallel to the Workengagng surface beyond Lthe articledriving means, and spaced from the base.

References Cited in the le of this patent UNITED STATES PATENTS Curtis May 18, Curtis May 18, Burger Apr. 8, Hanna May 9, Emst Sept. 19, Boynton July 24, Muir June 17, Shaft Aug. 1, Larson Dec. 23, Schairoth May 3, Mothorn Nov. 15, Schafroth Nov. 22, Van Sittert May 8, Wandel June 26, Fischer Nov. 6, Lang Nov. 6, Iuilfs Feb. 19, Dupre Aug. 18, Aldrich May 3, Schafroth et a1. Nov. 1, Faccou Ian. 3, Schafroth Nov. 20, Faccou Ian. 7,

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No., 2,989,948 June 2L, 1961 William A. Forrester It is hereby certified that error appears injbhel above numbered patent requiring correction and that the said Letters"L Patent should read as 'corrected below Column 2,: line 42, for "'anvile" read anvil column 3, line 18, after "trgger;" insert and --g line 58, for "it," read its column 6, line 10, after "its" insert main column 9, line 48 for "surfaced" read surface --g column 13, line 47, for "throught" read JEhrough column 16, line 15, for "relasable" read releasable.

Signed and sealed this 28th day of November 1961.

' (SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer i Commissioner of Patents USCOMM-DC-

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