US2303666A

US2303666A - Pneumatic percussive tool

Info

Publication number: US2303666A
Application number: US407030A
Authority: US
Inventors: Eugene H Souter
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-08-15
Filing date: 1941-08-15
Publication date: 1942-12-01
Anticipated expiration: 1959-12-01

Description

Dec. 1, 1942. .E.. H. SOUTER PNEUMATIC PERCUSSIVE TOOL Filed Aug. l5, 1941 5 Sheets-Sheet l E wS,

Dea 1, 1942- E. H. souTER PNEUMATIC PERCUssIvE Toon Filed Aug. l5. 1941 5 Sheets-Sheet 2 De- 1, 1942 E. H. SOUTER PNEUMATIC PERCUSSIVE TOOL Filed Aug, 15. 1941 5 Sheets-Sheet 3 mm. R m@ ma TTU/@VEZ Dec. l, 1942. y E. H. SOUTER 2,303,556

PNEUMATIC PERCUSS IVE TOOL Filed Aug. 15, 1941 5 Sheets-Sheet 4 INVENTOR. 2/ e/fe M 50a/ef Dec. 1, 1942. E. H. souTER PNEUMATIC PERCUSSIV-E TOOL 5 Sheets-Sheet 5 Filed Aug. l5, 1941 www.

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R. m m V m 2/ ne .50a/ef' @Trae/ven Patented Dec. 1, 1942 PNEUMATIC PERCUSSIVE TOOL Eugene H. Sonter, Independence, Mo.

Application August 15, 1941, Serial No. 407,030

29 Claims.

This invention relates to pneumatic tools of the single action type wherein is provided a floating piston; an air storage chamber; and means for automatically moving the piston tothe point of beginning of its working stroke and instantaneously applying the full force of the air from said air storage chamber to drive the piston through its working stroke without the use of mechanical latches or the like.

This invention has for one of its important 4aims to provide a pneumatic percussive tool of simple, compact character, provided with an air storage chamber in communication with a cylinder wherein is floatingly disposed a piston hammer, the connection between the storage chamber and cylinder being controlled by a valve member reciprocable to and from a position wheremotive uid fromthe source of supply is admitted to start the piston hammer through its power stroke.

A still further object of this invention is to provide a tool of the aforementioned character having a manually manipulatable throttle valve, an air ow control valve, means for storing motive fluid until the piston hammer is positioned to start its travel through the power stroke, and means including said air flow control valve for forcing the piston hammer through its return stroke when a predetermined pressure in the motive fluid storage chamber has been reached, said air flow control valve beingy spring-loaded and adjustably mounted whereby the pressure within the said storage chamber and which is attained prior to the movement of the piston hammer through its return stroke, may be selectively varied and predetermined.

Specific details of construction, the relation of the many novel parts embodying the invention constitute additional objects, all of which will be made apparent during the course of thev fol-4 lowing speciication, referring to the accompanying drawings wherein:

Fig. l is a side elevational view of a pneumatic percussive tool having parts thereof broken away to reveal details of structure.

Fig. 2 is a longitudinal central sectional view throughthe tool taken on line II-II of Fig. l.

Fig. 3 is a similar sectional view but taken on a plane perpendicular to the plane of section shown in Fig. 2 and taken on line III-III of Fig. 2.

Fig. 4 is a transverse cross .sectional view through the tool taken on line IV-IV of Fig. 2 and looking in the direction of the arrows.

' Fig. 5 is a similar view taken on line V-V of Fig. 2 and looking in the direction of the arrows.

Fig. 6 is a transverse sectional view taken on line VI-VI of Fig. 2 looking in the direction of the arrows.

Fig. '1 is a' cross sectional view taken on line VII- VII of Fig. 1 looking in the direction of the arrows.

Fig. 8 is a sectional view through the tool taken 011 line VIII-VIII 0f 3 looking in the vdirection of the arrows.

Fig. 9 is a fragmentary detailed sectional view taken on line IX-IX of Fig. 3.

Fig. 10 is a fragmentary sectional view taken on line X-X of Fig. 3.

Fig. 1l is an irregular fragmentary, longitudinal sectional view taken on line Xl-XI of Fig. 8 and looking in the direction of the arrows.

Fig. 12 is a fragmentary longitudinal sectional -view taken on line XII-XII of Fig. 11.

Fig. 13 is a fragmentary detailed sectional view taken on line XIII-MII of Fig. 3.

Fig. 14 is a longitudinal central sectional view through a, pneumatic percussive tool made in accordance with a modified form ofthe invention.

Fig. 15 is a side elevational view of the tool embodying a modified form of the invention.

Fig. 16 is a sectional view through a portion of the tool taken on line XVI-XVI of Fig. 14.

Fig. 17 is a cross sectional view taken on line XVII-XVII of 1518.14.

Fig. 18 is a fragmentary sectional view through a portion of the tool taken on line XVIII- XVIII of Fis. 14.

Fig. 19 is a cross sectional view taken on line XIX-XIX of Fig. 14.

Fig. 20 is a fragmentary irregular sectional view taken on line XX-XX of Fig. 19.

Fig. 21 is a fragmentary detailed sectional view taken on line XXI-XXI of Fig. 19; and

`Fig. 22 is asimilar view taken on line XXII- XXlI of Fig. 19. i'

Tools of the character contemplated by this invention, illustrated in the accompanying drawings and about to be described in detail, are in demand for riveting, punching and other work involving quick, decisive hammer blows and where but a single impact can be employed to produce efficient results. Simplicity, positive action, compactness and low cost of manufacture are desirable requisites of pneumatic percussive tools and the two forms shown in the accompanying drawings meet the demands of the industry in these respects and embody the objects of the invention to such a degree as to teach one skilled in the art the advantages thereof.

One form of the invention illustratedin Figs.

1 to 13 inclusive, comprises a case 30 having a space 38 for compressed air or the motive iluid.

Case 30 is externally threaded as at 38 at one end and provided with a shoulder 40 for the mounting of a head. generally designated by the numeral 42, a packing 44 is interposed between shoulder 40 and the annular rim of head 42. The end of case 30 opposite to head 42 isvreduced in diameter and internally threaded as at 48 to receive externally threaded holder 48 for the floating work engaging member 80. A stop 52 in holder 48 circumscribes member 50 and serves to absorb such force as is imparted thereagainst by hammer 34 when it reaches the end of its power stroke and has engaged member 60. Vents 54 arranged in an annular. path in case 30, are close to holes 68, milled in the wall of cylinder 32. This cylinder 32 rests in case 30 and is held therein by spacer lugs 58 between internal annular head 80 oi head 42 and the end of case 30. and the external integral annular flange 62 engaged by packing 64 adjacent the end of case 30 opposite tovhead 42.

A collar 65 circumscribing cylinder 32 and having a nipple 68 thereon, is slidably mounted and secured as at 68 to connecting rods 10, journalled near their one end in flange 62. and near-their opposite ends in spacer lugs 58. Each connecting rod has a spring 12 associated therewith, as illustrated in Fig. 2, to yieldably maintain rods 10 of collar 65. and the hereinafter more fully described valve member 14, in the position shown in Figs. 2 and 3. The ends of connecting rods 10 opposite to those ends secured to collar 65, are fastened to valve member 14 through the medium of ears 16. Connecting rods 10 are housed within storage chamber 36 and therefore, their movement cannot be effected by the operator when the tool is held by gripping case 30.

A socket 1,8 formed in flange 62 slidably receives the free end of nipple 66 and is in communication with conduit 80 extending longitudinally within chamber 36 to connect-with way 82 drilled or otherwise formed in head 42. This way 82 interconnects chamber 84 of the air now control valve, which is broadly designated by the numeral 86. A passage 88 formed in head 42 interconnects storage chamber 36 and valve member 14. A port 30 also interconnects storage chamber 36 and valve chamber 84.

Air escape aperture 92 formed to connect cavity 64 in head 42 to the atmosphere is beneath grip 96 and therefore, completely out of the way of the operator.

Valve member 14 is reciprocably journalled in head 42 and moves to and fro in cavity 94 during the operation of the tool. Valve member 14 has a cavity 15 in one end thereof and a longitudinal axial bore 98 joined by a radial branch |00, which registers with duct |02 when valve member 14 is at one end of its path of travel. This duct |02 extends to and joins passage |04 interconnecting air flow control valve 66 vand a throttle valve generally designated by the numeral |06. Valve member 14 is circumscribed by a packing gland |08 held in place by ring I0 in screwthreaded engagement with the internally threaded annular stepped wall of head 42.

Cylinder 32 and valve member 14 are in longitudinal alignment and the former has a seat ||2 thereon in opposed relation with gasket ||4 carried by an enlarged part of valve 14 that is in the form of an annular channel-shaped ange ||8. The forward flanged portion oi valve 14 is positioned in storage chamber 38 where the motive huid in said chamber may'act upon the outer rear face of valve member 14 and also on the end thereof formed. by annular flange H8. Air ilow control valve 88 is integral with head 42 and the chamber 84 thereof, is desirably formed by drilling inwardly from one end after which plug ||l is placed. Piston |20 of air flow control valve abuts projection |22 on plug ||8 to always maintain a space for .the reception of motive fluid from passage 88. The other end of piston |20 has a socket |24 therein to receive one end of rod |28 about which is coiled spring |28 and over a portion whereof is mounted thimble |30. Rod |28 is screwthreaded along a portion of its length and a kerf |32 and a ilange |34 through the medium oi' which rod |26 may be rotated to move thimble |30 longitudinally therealong to increase or decrease the tension of spring |28 upon piston |20. Thus, as will be more fully hereinafter described, the pressure required to move piston |20 may be set by the operator.

A plug |36 journals the opposite end of rod |26 from that end in socket |24. Piston |20 has -an annular groove |38 therein and a reduced portion |40, which increases in depth as the end oi piston |20 is approached. Throttle valve |08 is adjacent to air flow control valve 86 and is likewise formed in head 42, and comprises a plunger |42, held in the position shown in Fig. 3, by spring |44 when the operator is not exerting inward force upon knob |46 of said plunger. Throttle valve |06 controls the passage of motive uid from any source of supply to air iiow control valve 86. A conventional tting |48 joins valve |06 with hose |50 and when plunger |42 is in the position shown in Fig. 1, the annular groove |52 thereof is in register with air intake port |54. In addition to passage |04 which interconnects throttle valve |06 and air control valve 86, there is provided a connecting opening |56, an exhaust port |58 connects throttle valve to the atmosphere, and a groove |60 communicates with passage |04 and opening |56, whereby they are always joined regardless of the position of plunger |42. A radial pin |62 on thimble |30 rides in longitudinal slot |64 of that part of head 42 which houses rod |26, spring |28 and thimble |30. The outer face of head 42 'adjacent to the slot |64 has indicia |66 imprinted thereon to indlcate the pressure at which air flow control valve 86 will operate to cause piston hammer 34 tomove to the point of beginning and through its power stroke. This pin |62 also serves to preclude rotation of thimble I 30as itis moved longitudinally.

Operation Assuming that the parts o the tool are in the position shown in Fig. 3, and that the cycle of operation begins when the operator actuates throttle valve |06 by depressing plunger 42 thereof.

Piston hammer 34 may be at any station along the entire length of the cylinder 32 when this cycle of operation begins, but upon movement of plunger |42 to that position shown in Fig. l, where spring |44 is compressed, groove |52 will come into register with air intake port |54. Motive fluid being in most instances compressed air, will then enter the tool through hose |50, tting |48, intake port |54, groove |52 and then pass to the storage chamber 36 by way of passage |04, annular groove |36 of piston |20 and port 80.

When pressure in chamber 33 reaches a predetermined point, vestablished by the tension of spring |29 on piston |20, air enters chamber 04 behind piston through passage 33.. whereupon reduced portion is moved to'resister with and places in communication, connecting opening |56 and way 82 to direct air through conduit 30 to socket 13, nipple 63 and holes 56. formed in one end of the wall of cylinder 32. Hammer 34, therefore, is moved to the beginning point of its working stroke by air or motive iiuid of predetermined pressure in chamber 39. and vthe aforesaid parts directing said air against the forward end of hammer 34. As hammer 34 so moves, air from within cylinder 32 is adequately exhausted through bore 98 and air escape aperture 92.

It is conventional to maintain a pressure of anywhere from thirty to one hundred twenty pounds in chamber 36 during the commercial use of a percussive tool of the type embodying this invention. The pressure in chamber 36 is established and maintained for sending hammer 34 through its working stroke and after a desired predetermined pressure has been created in chamber 36 by the operation of the equipment, just above set down, groove |38 of piston |20 is in that position shown in Fig. 1, where air can no longer enter through port 90.

As was clarified during the description of the parts of the pneumatic percussive tool, the air pressure established in chamber 3'6, is determined by setting pin |62 at aposition on scale |66 that designates the pressure per square inch established in the storage chamber. Spring |26 has its tension varied by introducing a screwdriver into kerf |32 and turning rod |26 to move thimble |30 longitudinally thereof, untill the spring has been tensioned as desired.

With the pressure in chamber 36 so established,

of member 14. Piston 34 becomes the seal to preclude entrance of air into cylinder 32 and bore98 until it is forced forwardly, as laterdescribed.

As collar 65 moves rearwardly, the passage through nipple 66 is closed to interrupt the flow of air into cylinder 32 by virtue of moving the end of passage in nipple 06 out of register with hammer 34 will have a pressure built up in front 40 thereof to slightly move valve member 14 from seat H2, whereupon pressure in chamber 36 `will force valve member 14 back to theposition shown in Fig. 1. Obviously, such movement of valve member 14 is occasioned by the presentation to the pressure in chamber 36, of a greater surface against which the air in said chamber may act.

Hammer 34 has a portion of its length within cavity 15 and travels rearwardly with member 14. -As member 14 continues to increase its disstance from valve seat I I2, collar 65 will be drawn longitudinally along the outer face of the wall of cylinder 32 to open holes 56 to the atmosphere by way of vents 54. Such action is made positive through the medium of connecting rods 10, but the rearward movement of valve member 14 and collar -65 occurs only when the tension of springs 12 is overcome.

Air in chamber 36 is exerting pressure against the rear face of flange I6 and this pressure must also be overcome. 'The diameter of member 14 rearwardly of flange H6, may be, for example, 111g in., while the diameter of seat H2 is 11% in. The difference between-these diameters is-the element insuring an air-tight relation between seat ||2 and gasket H4.

Rearward movement of member 14 is caused by air exerting pressure against the face of ange H6 where gasket H4 is positioned. The effective area of this face is instantaneously increased when said gasket is moved from seat H2. The difference between the inside diameter of member 14 (diameter of cavity 15), and the outside diameter of member 14, rearwardly of flange H6,

is the element insuring quick rearward movement one of holes 56. ,The reason for providing a relaL tively deep socket 16 is to allow for the movement of collar 95, while nipple 66 remains in communication with conduit 00.

The parts of the tool are now in the position shown in Fig. 1, and piston 34 is .bridging the space between cylinder 32 and valve member 14.

When valve member 14 attains the position shown in Fig. -l, radial branch |00 from bore 08 is in register with one end of duct |02, the other end of which communicates with passage |04, establishing connection between throttle valve |06 and air ow control valve 86. Air, therefore, is directed against the rear end of hammer 34, which air originates at the source of supply of the motive fluid. Instantly upon the movement of piston 34, until the rear end thereof passes beyond the end of valve member 14, piston 34 will receive the full force of the motive uid under pressure in storage chamber 36., because said storage chamber is in direct connection with cylinder 32 through the space established between the end of cylinder 32, whereat is disposed seat ||2 and the proximal end of valve member 14. High velocity is therefore imparted to piston 34. Due to the relatively great effective area of the space between cylinder 32 and valve member 14, the full eiect of motive fluid pressure in chamber 36 is obtained and hammer 34 will be driven through its working stroke and lagainst the work engaging member 50 with that degree of velocity and force necessary to fulfill the exacting requirements of pneumatic percussive tools of the character here involved.

In some positions of the tool, piston 34 may move by gravity from within cavity 15, and air is introduced therebehind .to insure forward movement of the floating piston 34, regardless of the position of the tool with relation to gravity.

When piston 34 moves through its working stroke, as just set down, air in cylinder 32 is exhausted to the atmosphere through holes 56 and vents 54 with suicient speed and in suilicientl volume to reduce to the greatest possible minimum, any back pressure against piston 34 as it is being driven toward member 50. Only atmospheric pressure exists in front of piston 34 when it starts its Working stroke, due to the aforesaid opening of holes '56 by movement of collar 64, 'which'exhausted air under pressure that served to drive piston 34 toward the point where `its working stroke begins. l

Being a percussive tool of the single shot type,

i it must be assumed in normal operation and for purpose-of this disclosure, that-the operator will immediately release his hold upon plunger |42 when piston 34 has struck member 50. So long as plunger |42 is depressed, however, no loss of motive fluid through bore 98 from chamber 36 can occur due to the aforesaid supply of motive fluid from the source to bore 98 through branch |00 and duct |02. This supply is in excess of the exhausting capacity of bore 98. When plunger |42 has returned to the normal point of beginning, illustrated in Fig. 3, through the force of spring |44, its groove |52 will register with exhaust port |58, extending outwardly through the V head 42. 'I'his port |58 therefore, functions to:

Such exhausting or lowering o! the pressure in storage chamber 36. does not occur until motive iluid in chamber 36 has escaped through bore 98 and aperture 92 to a sufficient degree to permit spring |28 to move piston |20 back to its normal position, shown in Fig. 3. Such action will bring groove |38 into a position interconnecting port 98 and passage |04.

If the operator does not release plunger |42 immediately upon completion of the working stroke oi piston 34, pressure in chamber 36 will be again built up to a point overcoming spring |28 to move piston |20 forwardly, placing out of register groove |38, port 60 and passage |04. In A..

such condition, air must be exhausted through bore 98 to. a suilicient degree to allow spring |28 to return piston to normal position. When the air is so exhausted, springs 12 exerting their force upon rods 10, will return member 14 to a position where its gasket ||4 is again against seat ll2.

The pneumatic percussive tool, illustrated in Y Figs. 14 to 23 inclusive, embodies a modified form of the invention but has an operating head thereon substantially similar to the tool previously described and shown in Figs. 1 to 13 inclusive.

It is desirable to provide pneumatic tools having relatively short working strokes to accomplish some results. and since the compressors normally employed do not provide line pressures high enough to allow short strokes of the piston hammer, means is provided in the form of the invention about to be described, for further compressing the air or motive fluid immediately prior to its introduction to that part of the device where the piston hammer is located. Suchcompression is accomplished through the force exerted by air or the motive fluid derived from the commercial type compressors.

Case 224 is T-shaped and the stem thereof has a storage and compression chamber 226, a compressor cylinder 228, and a

piston having heads

230 and 232 on the ends respectively of piston rod 234. As illustrated in Fig. 14, head 230 is relatively small in diameter as regards head 232. A removable end wall 236 permits introduction of the piston.

The head of T-shaped case 224 has a cylinder 238 formed therein and a piston hammer 240 iloatingiy received thereby. This piston 240 lll moves through a forward path of travel which is Y hereinafter designated as the power stroke, and through a rearward path of travel, which is herein designated the return stroke.

A holder 242 in screwthreadedl engagement with porting holder 242, is normally closed by a valve "member 254. This valve member has a gasket 256 for direct engagement with seat 258 projecting from the end of the cylinder. An air escape aperture 260 in cap 262 is adjacent tobore264 formed axially through valve member 264 at one eng thereof. while cavity 266 is at the opposite en v A radial branch 266 communicates with bore` 264 `and has its outer end in connection` with an annular grove 288, which grooveregisters with duct 210 .under certain conditions to be hereinafter described. This duct 210 has one end in connection with air storage and compression chamber.

A throttle valve.I broadly designated by the numeral 212, comprises a plunger 214 with two annular grooves 216 and 218 respectively therein. Trigger 280 bears against one end of plunger 214 to move the same against spring 282 when the tool is to be operated. The cavity 284 forming a part of throttle valve 212, has an exhaust port 286 extending to the atmosphere therefrom. An air-flow control valve, generally designated by the numeral 288. is integral with case 224 and comprises a piston 230 having two

grooves

232 and 294 respectively therein.

Rod 286 circumscribed by spring 238 is adjustably mounted for rotation in control valve 226, and thimble 300 in screwthreaded engagement with rod 286, moves longitudinally therealong as the rod is rotated-thus, the thimble is actuated to vary the tension of spring 288 and the pressure at which the tool will operate is designated on a scale 302, adjacent slot 304, through which passes pin 306 extending radially from thimble 300.

Passage 808 provided in case 224 joins valve 288 with compression chamber 226 and conduit 3|0 formed in case 224, interconnects valve 288 with the annular groove 8I2 formed in collar 250. It is through this conduit that air passes tomove piston240 through its return stroke.

Both valve 212 and 288, as illustrated, are in the normal position where the tool is not in operation but is joined to a source of motive iluid or compressed air through the medium of hose 3|4 and tting 3|6. A main air duct 3|8 extends from fitting 3 i 6 to a point adjacent to the throttle valve 212 where it joins way 320, charging duct 322 and passage 324, all of which are intersected by plunger 214. Way 320 extendsfrom throttle valve 212 to the inner end of compression cylinder 228. 'I'he charging duct 322 extends to storage and compression chamber 226 to charge the same, and passage 324 extends to air control valve 266 where two

lateral branches

326 and 328 join

passages

330 and 332 respectively. Passage 330 is in connection with conduit 3|0 (see Fig. 18), and passage 332 extends through case 224 to a. point always behind head 232 (see Fig. 20). An exhaust 334 to the atmosphere extends from -throttle valve 212 and an extension 336 on way 320 likewise leads to the atmosphere and serves as an exhaust.

Operation With the parts of the pneumatic percussive tool in the position shown in Figs. 14 to 22 inclusive, the operator need but move trigger 286 in the direction of the arrow, shown in Fig. 14, to cause piston 240 to move through its power stroke.- When trigger 280 is so moved, plunger 214 oi throttle valve 212 will move against spring 282 where motive iiuid or compressed air, as said iluid will hereinaiter be designated, will pass from the source of supply through hose 3|4, iitting 3|6 and air inlet channel- 3|8 to passage 324 by way of groove 218 in plunger 214.

Groove 216 in plunger 214 will interconnect extension 336 and exhaust port 286 to remove air from compression cylinder 228 that is in front of head 232. Duct 322 is at the same time, closed to impound the air that has entered storage chamber 226 therein and permit compression thereof. As pressure in chamber 226 is built up piston 298 is forced, by air entering therebehind through passage 388, against spring 2.98 to interconnect branch 326 and passage 338. .This action supplies air to conduit 3I8 and drives piston 248 toward member 254. As the piston so moves, air is exhausted through bore 264 and to atmosphere through aperture 268. Air from chamber 226 is exhausted, to allow springs 342 to return valve member 254 to its seat, through bore 264 and aperture 268.

As valve member 254 was moved from seat 258 of cylinder 238 by piston 248, collar 258 was drawn by connecting rods 348 to a position where holes 252 were opened and conduit 3I8 closed. Such action was against thev force of springs 342. Air in chamber 226 is exerting pressure against the rear face of member 254 that is disposed in that portion of chamber 226 in case 224, and this pressure must also be overcome. The diameter of member 254 rearwardly of that enlarged portion holding gasket 256, is less than the diameter of seat 258. The difference between these diameters is the element insuring an air-tight relation between seat 258 and gasket 256.

Rearward movement of member 254 is caused by air exerting pressure against the face of gasket 256 and that portion of member 254 in the plane with said face. The effective area of this face is instantaneously increased when said gasket is moved from seat 258. The difference between the inside diameter of member 254 (diameter of cavity 255), and the outside diameter of member 254 rearwardly of the enlarged portion, is the element insuring quick rearward movement of member 254. Piston 248 becomes the seal-to preclude entrance of air into cylinder 238 and bore 264 until it is forced forwardly as later described.

As piston 248 moved through its power stroke, the air within cylinder 238 was exhausted through holes 252 and to the atmosphere by way of vents 248, through which the air that moved piston 248 through its return stroke, was exhausted as soon as the piston reached a position against valve member 254 and when said member had suiciently moved to open said holes 252.

When the single shot action just above set out is complete. the operator will obviously, release trigger 288 and allow plunger 214 to return to the position shown in Figs. 14 and 20. Groove 216 will then interconnect way 328 and main channel 3|8 to introduce into cylinder 228, in front. of head 232, a supply of air from the source to drive the double headed piston back to the point of beginning, shown in Fig. 14. Simultaneously with this action, air from in front of head 232 must be and is exhausted through passage 332 and branch 344 to exhaust port 334 that is rendered accessible through the cavity forming a part of throttle valve 212, from which plunger 214 has passed to uncover the same, and thus, allowing air to escape from in front of head 232 to the atmosphere as said head is driven to its point of beginning.

The air which returns the piston to its point of beginning enters compression cylinder through both way 328 and duct 322 until head 238 reaches the position shown in Fig. 21, whereupon air emanating from duct 322 will remain in storage chamber 226 to again charge the same.

Having thus described the invention, what isclaimed as new and desired to. be secured by Letters Patent is:

1. In a pneumatic percussive tool of the character described having a cylinder and a piston freely movable in the cylinder through a power stroke and a return stroke, a storage chamber for motive :duid in communication with the cylinder at an end thereof; a valve member movable to and from a normal position interrupting the flow of the fluid from said storage chamber to the cylinder at said one end; and means for supplying motive fluid to the other end of the cylinder to force the piston through its return stroke when a predetermined pressure is reached in the storage chamber.

2. In a pneumatic percussive tool of the character described having a cylinder and a piston freely-movable in the cylinder through a power stroke and a return stroke, a storage chamber for motive fluid in communication with the cylinder at an end thereof; a valve member movable to and from a normal position interrupting the flow of the uid from said storage chamber to lthe cylinder at said one end; and means for 4 supplying motive fluid to the other end of the cylinder to force the piston through its return stroke when a predetermined pressure is reached in the storage chamber, said valve member being moved from the normal position by the piston the other end of the cylinder to force the piston throughits return stroke when a predetermined pressure is reached in the storage chamber, said valve member being moved from the normal position by the piston as it approaches the end of its return stroke,4 said valve member having a bore therein in connection with the source of supply of motive fluid when at the end of its path of travel from the normal position to start the piston through its power stroke.

4. In a pneumatic percussive tool of the character described having a cylinder and a piston freely movable lin the cylinder through a power stroke and a return stroke, a storage chamber for motive fluid in communication with the cylinder at an'end thereof; a valve member movable to and from a normal position interrupting the iiow of the uid from said storage chamber to the cylinder at said one end; and means for supplying motive iiuid to the other end of the cylinder to force the piston through its return stroke when a predetermined pressure is reached in the storage chamber, said valve member being moved from the normal position by the piston as it approaches the end of its return stroke, said valve member having a cavity formed therein in alignment with the cylinder, the piston having a portion in the cavity and a portion thereof in the cylinder when at the end of its return stroke.

5. In a pneumatic percussive tool of the character described having a cylinder and'a piston freelymovable in the cylinder through a power stroke and a return stroke, a storage chamber for motive iiud in communication with the cylinder at an end thereof; a valve member movable to and from a normal position interrupting the flow of the fluid from said storage chamberto the cylinder at said one end; and'means for supplying motive fluid to the other end of the cylinder to force the piston through its return stroke when a predetermined pressure is reached in the storage chamber, said valve member being y moved from the normal position by the piston as it approaches the end of its return stroke, said valve member having a cavity formed therein in alignment with the cylinder, the piston having a portion in the cavity and a portion thereof in the cylinder when at the end of its return stroke, said piston when in such position serving to bridge the distance between the cylinder and said valve member.

6. In a pneumatic percusslve tool of the character described, a case having .a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke, a storage chamber for motive iiuid in communication with the cylinder at one end thereof; inlet holes formed at the other end of the cylinder; a valve normally in position to supply motive iluid to the storage chamber; means for conveying motive fluid from the valve to the inlet holes to move the piston through its return stroke when the said valve is in a certain position; and a passage provided in the case, interconnecting the storage chamber and said valve to operate the latter when a predetermined Vpressure is reached in the storage chamber, said valve being in the said certain position to cause return of the piston when the predetermined pressure is attained.

7. In a pneumatic percussive tool of the character described, a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke. a storage chamber for motive fluid in communication with the cylinder at one end thereof; inlet holes formed at the other end of the cylinder; a valve normally in position to supply motive fluid to the storage chamber; means for conveying motive fluid from the valve to the inlet holes t move the piston through its return stroke when the.

said valve is in a certain position; a valve member movable to'and from a normal position interrupting the flow of the iiuid from said storage chamber to the cylinder at said one end; a passage provided in the case, interconnecting the storage chamber and said valve to operate the latter when a predetermined pressure is reached in the storage chamber; a closure for the inlet holes; and structure interconnecting the valve member and said closure to shift the latter to a position closing the holes when the valve member is moved from its normal position.

8. In a pneumatic percussive tool of the character described, a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke. a

said member to the other end of its kpath of travel; and means operable when the valve member reaches its said other end of its path of travel for supplying motive uid to the cylinder to start the piston through its power stroke.

9. In the pneumatic Apercussive tool o'f the character described, a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke, a storage chamber for motive fluid in communication with the cylinder at one end thereof; a reciprocable valve member in the storage chamber, in alignment with the cylinder and closing said one end thereof when at one end of its path of travel; means for supplying motive fluid to the cylinder to move the piston through its' return stroke and against the valve member to initially shift the same to a position where fluid pressure in the storage-chamber will force the said member to the other end of its path of travel; and means operable when the valve member reaches its said other end of its path of travel for supplying motive fluid to the cylinder to start the piston through its power strolre,y said valve member being formed to isolate a portion of the piston from the action of the motive fluid in the storage chamber until after the piston has started through its power stroke.

10. In a pneumatic percussive tool of the character described, a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke, a

l storage chamber for motive uid in communicastorage chamber for motive' fluid in communication with the cylinder at one end thereof; a reciprocable valve member in the storage chamber, in alignment with the cylinder and closing said one end thereof when at one end of its path of travel; means for supplying motive fluid to the cylinder to move the piston through its return stroke and against the valve member to initially shift the same to a position where fluid pressure in the storage chamber will force the tion with the cylinder at one end thereof: a reciprocable valve member in the storage chamber, in augment with the cylinder and closing said one end thereof when at one end of its path of travel; means for supplying motive iiuid to the cylinder to move the piston through its return stroke and against the valve member to initially shift the same to a position where fluid pressure in the storage chamber will force the said member to the other end of its path of travel; and means operable when the valve member reaches its said other end of its path of travelfor supplying motive iiuid to the cylinder to start the piston through its power stroke, said case being provided with holes for exhausting air from the other endof the cylinder as the piston travels through its power stroke, said holes having a closure there:

for movable to a position opening the holes when the said valve member returns to said Vone end of its path of travel. Y

11. In a pneumatic percussive tool of the char-.- acter described, a case having a cylinder thereinv and a piston freely movable in the cylinder throngh a power stroke and a return stroke, a storage chamber for motive iiuid in communication with the cylinder at one end thereof; a

reciprocable valve member in the storage chamber, in alignment with the cylinder and closing said one end thereof when at one end of its path of travel; means for supplying motive fluid to the cylinder to move the piston through its return stroke and against the valve member to initially shift the same to a position where fluid pressure in the storage chamber will force the said member to the other end of its path of travel; and means operable when the valve member reaches its said other end of its path of travel for supplying motive huid to the cylinder to start the piston through its power stroke. said case being provided with holes for exhausting air from the other end of the cylinder as the piston travels through its power stroke, said holes having a closure therefor movable to a position opening the holes when the said 4Valve member returns to said one end of its path of travel, said valve member and closure having means for yieldably holding the same 'in position where the valve member is closing the said one end of the cylinder and the closure is closing the said holes.

12. In a pneumatic percussive tool of the character described, a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke,

a storage chamber for motive fluid in communication with the cylinder at one end thereof; a

reciprocable valve member in the storage chamber, in alignment with the cylinder and closing said one end thereof when at one end of its path of travel; means for supplying motive fluid to the cylinder to move the piston through its `return stroke and against the valve member to initially shift the same to a position where fluid pressure in the storage chamber will force the said member to the other end of its path of travel; means operable when the valve member reaches its said other end of its path of travel for supplying motive fiuid to the cylinder to` start the piston through its power stroke; a throttle valve for causing motive fiuid to enter the storage chamber when in one position; and an exhaust port controlled by the throttle valve and serving to exhaust uid from the storage chamber when in another position where the flow of motive fluid to the said chamber is interrupted.

13. In a pneumatic percussive tool of the character described, a case having a cylinder therein and a piston freely movable in the cylinder through a. power stroke and a return stroke, a storage chamber for motive fiuid in communication with the cylinder at lone end thereof; inlet holes formed at the other end of the cylinder; a valve normally in position to supply motive fluid to the storage chamber; means for conveying I motive fluid from the valve to the inlet holes to move the piston through its return stroke when passage provided in the case, interconnecting the storage chamber and said valve to operate the latter when a predetermined pressure is reached in the storage chamber; a closure for the inlet hOleS;

member and said closure to shift the latter to closin the holes when the valve memlaael-(issu'rorwed frorgn its normal position, said structure comprising rigid parts insuring unitary movement of the valve member, and spring yieldably holding the unitary struct-ure at one en f trave Gillis Iliiahpieumatic percussive tool of the character described, a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke, a storage chamber for motive fiuid in communication with the cylinder at one end thereof; a valve member movable to and from a position interrupting the flow of motive fluid from the storage chamber to the cylinder disposed in the storage chamber; and means for moving the piston against the valve member, said cylinder having fa'ce opposed to the valve seat and a second face and structure interconnecting the valve an annular seat, said valve member having a ,against which motive fluid acts to maintain the first mentioned face against the seat.

15. In a pneumatic percussive tool of the character described. a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke, a

storage chamber for motive iluidin communication with the cylinder at one end thereof; a valve member movable to and from ra position interrupting the flow of motive fluid from `the storage chamber to the cylinder disposed in the storage chamber; and means for moving the piston against the valve member, said cylinder having an annular seat, saidn valve member having a face opposed to the valve seat and a second face against which motive fluid acts to maintain the first mentioned face against the seat, said first mentioned face being of greater area than the lsecond face, said annular seat lserving to isolate a part of the area of the first mentioned face, when the valve is seated, and leave exposed in the storage chamber a smaller area thereon than the area of the second mentioned face whereby the valve member is maintained seated by motive fluid in the storage chamber until displaced from its said seat.

16. In a pneumatic percussive tool of the character described, a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke, a storage chamber for motive fluid in communication with the cylinder at one end thereof; a valve member movable to and from a position interrupting the fow of motive fluid from the storage chamber to the cylinder disposed in the storage chamber; and means for moving the piston against the valve member, said cylinder having an annular seat, said valve member having a face opposed to the \valve seat and a second face against which motive fluid acts to maintain the first mentioned face against theseat, said first mentioned face being of greater area than the second face, said annular seat serving to isolate a part of the area ofthe first mentioned face, when the valve is seated, and leave exposed in the storage chamber a smaller area thereon than the area of the second mentioned face whereby the valve member is maintained seated by motive fluid in the storage chamber until displaced from its said seat. said means for moving the piston against the valve member being sufficiently forceful to carry the latter from .the said seat.

17. In a pneumatic percussive tool of the character described, a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke, a storage chamber for motive fluid in communication with the cylinder at one end thereof; a valve member movable to and from a position interrupting lthe flow of motive fluid from the storage chamber to the cylinder disposed in the storage chamber; and means for moving the piston against the valve member, said cylinder having an annular seat,said valve member having a face opposed to the valve seat and a second face against which motive fluid acts to maintain the vfirst mentioned face against the seat,'said first mentioned face being of greater area than ythe second face, said annular seat serving to isolate a part of the area of the first mentioned face, when the valve is seated, and leave exposed in the storage chamber a smaller area thereon than the area of the second mentioned face whereby thevalve member is maintained seated by motive fluid in the storage chamber until displaced from p its said seat, said means for moving the piston against the valve member being sumciently forceful to carry the latter from the said seat, said valve member being provided with a bore for exhausting air from the cylinder as the piston is moved toward the valve member.

18. In a pneumatic percussive tool of the character described, a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke, a storage chamber for motive fluidi in communication with the cylinder at one end thereof; a valve member movable to and from a position interrupting the flow oil motive uid from the storage chamber to the cylinder disposed in the storage chamber; and means for moving the piston against the valve member, said cylinder having an annular seat, said valve member having a face opposed to the valve seat and a second face against which motive uid acts to maintain the `first mentioned face against the seat, said first mentioned face being of greater area than the second face, said annular seat serving to isolate a part of the area of the first mentioned face,

when the valve is seated, and leave exposed in the storage chamber a smaller area thereon than the area of the second mentioned face whereby the valve member is maintained seated by motive fluid in the storage chamber until displaced from its said seat, said 'means for moving the piston against the valve member being sufficiently forceful to carry the latter from the said seat, said piston serving to preclude entrance of motive iluid into the cylinder after the valve member has been moved from against the seat and while all the area of the rst mentioned face is exposed to the action of motive fluid in the storage chamber.

19. In a pneumatic percussive tool of the cliaracter described, a case having a cylinder therein and a piston freely movable in the cylinder through a power stroke and a return stroke, a storage chamber for motive iluid in communication with the cylinder at one end thereof; a valve member movable to and from a position interrupting the iiow of motive duid` from the storage chamber to the cylinder disposed in the storage l acter described having a cylinder and a piston chamber; and means for moving the piston 'the area of the second mentioned face whereby the valve member is maintained seated by motive fluid in the storage chamber untildisplaced from its said seat, said means for moving the piston against the valve member being suiilciently forceful to carry the latter from the said seat, said piston serving to preclude the entrance of motive freely movable in the cylinder through a working stroke and a return stroke; a storage chamber for motive fluid in communication with the cylinder at one end thereof; a valve member movable to and from a normal position interrupting the flow of the fluid from said storage chamber to the cylinder; a throttle valve for admitting uid under pressure to the tool from a source of supply; a fluid flow control valve; and means operable by fluid from the source of supply for raising the pressure of the motive fluid 'in the storage chamber prior to its entranceinto the cylinder to drive the piston through its working stroke.

21. In a pneumatic percussive tool of the character described having a cylinder and a piston freely movable in the cylinder through a working `operable by fluid from the source of supplyfor raising the pressure of the motive fluid in the storage chamber prior to its entrance into the'\ cylinder to drive thepiston through its working stroke, said duid flow control valve being spring loaded and connected to the storage chamber and the valve member by parts of the tool to cause movement of the valve member from its said normal position when the fluid in the vstorage chamber reaches a predetermined pressure.

22. In a pneumatic percussive tool of the character described having a cylinder and a piston freely movable in the cylinder through a working stroke and a return stroke; av storage chamber for motive fluid in communicationwith the cylinder at one end thereof; a valve member movable to and from a normal position interrupting the ow of the iiuid from said storage chamber to the cylinder; a throttle valve for admitting fluid under pressure to the tool from a source of supply; a fluid flow control valve; passages formed in the case for supplying fluid 'to the other end of the cylinder to force the piston through its return stroke; and means operable by fluid from the source of supply for raising the pressure of the motive uid in the storage chamber prior to its entrance into the cylinder.

23. In a pneumatic percussive tool of the character described having a cylinder and a piston freely movable in the cylinder through a working stroke and a return stroke; a storage chamber fluid into the cylinder after the valvemember has been moved from against the seat and while all the area of the first mentioned face is exposed to the'action of motive uid in the storage chamber, said valve member being in connection with a source of motive fluid to project the piston into the cylinder a sumcient distance to receive the full eiIect of motive fluid in the storage chamber when moved a distance from the seat.

20. In a pneumatic percussive Ytool of the charfor motive fluid in communication with the cylinder at one end thereof; a valve member movable to and from a normal position interrupting the flow of the uid from said storage chamber to the cylinder; a throttle valve for admitting fluid under pressure to the tool from a source of supply; a iluid flow control valve; passages formed in the case for supplying fluid to the other end of the cylinder to force the piston through its return stroke; and means operable by fluid from the source of supply for raising the pressure of the motive uid in the storage chamber prior to its entrance into the cylinder, said piston serving to open the valve member as it approaches the end of its return stroke.

24. In a pneumatic percussive tool of the character described having a cylinder and a piston freely movable in the cylinder through a working stroke and a return stroke; a storage chamber determined pressure.

inder at one end thereof; a valve member'mov` able to and from a normal position interrupting the flow of the fluid from said storage chamber to the cylinder; a throttle valve for admitting fluid under pressure to the tool from a source of supply; a uid ow control valve; passages formed in the case for supplying iiuid to the other end of the cylinder to force the piston through its return stroke; and means operable by uid from the source of supply for raising the pressure of the motive fluid in the storage chamber prior to its entrance into the cylinder, said uid flow control valve being adapted to automatically move to a position interconnecting the passages supplying iiuid to return the piston when the fluid in the storage chamber reaches a pre- 25. In a pneumatic percussive tool of the charactexdescribed having a cylinder and a piston freely movable in the cylinder through a working stroke and a return stroke; a storage chamber for motive uid in communication with the cylinder at one end thereof; a valve member movable to and from a normal position interrupting the iiow of the fluid from said storage chamber to the cylinder; a throttle valve for admitting fluid under pressure to the tool from a source of supply; a fluid iiow control valve; passages` formed in the case for supplying uid to the other end o! the cylinder to force the piston through its return stroke; and means operable 'v by 'fluid from the source of supply for raising the raising the pressure when the fluid in the storage chamber reaches a predetermined pressure.

26. In a pneumatic percussive tool of the character described having a cylinder and a piston freely movable in the cylinder through a Working stroke and a return stroke; a storage chamber for motive uid in communication with the cylinder at one end thereof; a valve member movableto and from a normal position interrupting the now of the uid from said storage chamber to the cylinder; a throttle valve for admitting uid under pressure to the tool from a source of supply; a fluid flow control valve; a compression cylinder in alignment with the storage chamber; and a piston having a head movable in the storage chamber and a head of relatively large diameter in the compression cylinder; said case having passageways interconnecting the throttle valve and the storage chamber and compression cylinder for movingthe piston to raise the pressure of themotive iiuid in the storage chamber prior to its entrance into the cylinder to drive the pressure of the motive fluid in the storage chaml ber prior to its entrance into the cylinder, said duid ow control valve being adapted to automatically move to a position interconnecting the passages supplying fluid to return the piston and to interrupt the ilow of fluid to the means for piston through its working stroke.

2'7. A pneumatic percussive tool ofthe character described in claim 26, wherein the aligned storage chamber and compression cylinder having' their axes perpendicular to the longitudinal axis of the cylinder through which the piston travels.

28. A pneumatic percussive tool of the character set forth in claim 20, wherein the storage chamber extends radially from the cylinder.

29. A pneumatic percussive tool of the character set forth in claim 20, wherein the storage chamber and means for raising the pressure of themotive uid therein are in alignment and extend substantially .radially from the cylinder through which travels the said piston.

EUGENE SOUTER.