US3866493A

US3866493A - Air-operated hand tool

Info

Publication number: US3866493A
Application number: US456457A
Authority: US
Inventors: Chester A Ringerud
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-04-01
Filing date: 1974-04-01
Publication date: 1975-02-18
Anticipated expiration: 1992-02-18

Abstract

What is disclosed is an air-operated hand tool which utilizes pressurized air to drive a screw, set a nut, or perform other similar tasks. The tool is hand-held and its driving mechanism is activated when the tool is pressed against the screw, nut or other item being worked. The tool may also be utilized as a handoperated tool and allows instant conversion from the poweroperated mode to the hand-operated mode.

Description

Unlted States Patent 11 1 1111 3,866,493

Ringerud Feb. 18, 1975 AIR-OPERATED HAND TOOL 3,329.185 7/1967 Hcttich et al. 81/59.]

[76] Inventor: ChestenA. Ringerud, 5537 Dundee FOREIGN PATENTS OR APPLICATIONS Edma Minn 55436 1.949.415 3/1969 Germany 8l/57.ll [22] Filed: Apr. 1, 1974 pp NO I 456 457 Primary Examiner-James L. Jones, Jr.

57 ABSTRACT [52] U.S.Cl ..81/5711,8l/57.39,81/58.1 l 1 Int. Cl- What IS dlsclosed IS an alr-operated hand tool WhlCh [58] Field o{Search 81/57 H 5 31 57 39 utilizes pressurized air to drive a screw, set a nut, or 0 5 perform other similar tasks. The tool is hand-held and s I its driving mechanism is activated when the tool is d a ainst the screw nut or other item being [56] References Cited pregse g worked. The tool may also be utillzed as a hand- UNITED PATENTS operated tool and allows instant conversion from the ghitkledtge power-operated mode to the hand-operated modev ac 1n on... 2973,1376 3/1961 Nelson 81/524 R 8 Claims, 8 Drawing Figures 50 i n i V i h l 34 AIR-OPERATED HAND TOOL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to a hand tool for driving screws, setting nuts and performing similar tasks by using either pressurized air or manual effort as the driving force.

2. Description of the Prior Art Air driven hand tools have long been used to save time and reduce physical effort in performing tasks of a relatively simple and repetitive character. Such tools are found particularly useful in high volume assembly operations requiring the repetitious driving of screws and setting of nuts. The use of pressurized air to drive such tools allows the use of a common source of power with relatively simple driving mechanism contained within the tool itself. The pressurized air is usually distributed to individual tools through flexible hoses which attach to the tools.

The utilization of pressurized air to drive the tools and its control is effectuated by various means in the existing art. In certain instances the compressed air is converted into a rotary motion by the use of an air turbine (see Patents: E. R. Whitledge, U.S. Pat. No. 2,484,364; E. D. Burnett et al., U.S. Pat. No. 3,323,395; and R. C. Blackinton, U.S. Pat. No. 2,786,379). This method of providing a rotational movement from the pressurized gas uses a relatively large amount of pressurized air in the turning of the turbine blades. It may find limited application in instances where it is desired to conserve the energy being used to provide the pressurized air. An alternative type of device for providing a rotational movement from pressurized air is the use of a reciprocating piston in the tool. This concept has been used in U.S. Pat. No. 2,484,364 (Supra) and in U.S. Pat. No. 2,973,676 by G. R. Nelson.

There are two general means by which the rotary motion of these tools is controlled. The first is the use of a triggerlike device which controls the flow of air to the hand tool. (See U.S. Pat. Nos. 2,973,676 and 3,323,395. Supra). The use of such a trigger device may in some instances restrict the ease with which a tool is handled by making the modes of gripping the tool less versatile and perhaps interfering with the exertion of a firm grip upon the tool. An alternative means of controlling the application of power to the tool is the use of a pressure sensitive switching means. Such a means reacts to pressure being exerted upon the tool bit when in use. This pressure in turn activates a valve means to control the flow of compressed air to the tool (see U.S. Pat. No. 2,484,364, Supra).

The use of compressed air to operate compact, handheld tools provides a relatively limited supply of power with which a nut or screw can be driven. This is due to the necessary limitation of tool part size and weight restrictions. In particular, the limited size and strength of the vein assembly in a turbine type tool and the limited size and strength of the piston means in a reciprocating piston tool limits the maximum amount of torque which such tools can produce. As a result, if in the operation to which the tool is being applied, a particularly difficult screwing or bolting operation arises for which the hand tool power is insufficient, a larger tool or a separate hand tool must be used to complete the task. This limits the versatility of existing air powered hand tools.

SUMMARY OF THE INVENTION The Applicants invention is an improved airoperated hand tool which has a manual operation capability. The tool is powered by pressurized air which enters the tool through a flexible hose. The pressurized air drives a reciprocating piston which in turn imparts a rotary motion to an interchangeable tool bit. The supply of pressurized air to the piston is controlled by a mechanical switch which opens and closes a flow-control valve in response to the tool bit being engaged and disengaged from a workpiece. This provides a simple means of turning the tool on and off without the use of a hand operated trigger or similar device.

The proposed invention has a unique manualoperation capability. At the end of the power stroke of the piston, a double clutch arrangement allows the tool bit to be turned by rotating the tool body by hand. In this manner the tool becomes a hand-tool which can be used to selectively tighten the workpiece or to com- 1 plete a task which the power operation was incapable of performing due to its limited torque capability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a preferred embodiment of the air-operated hand tool.

FIG. 2 is a cross-sectional view through a vertical plane of the embodiment illustrated in FIG. 1.

FIG. 3 is a sectional view as seen from the line 3-3 showing the double clutch arrangement.

FIG. 4 is a partial sectional view as seen from the line 4-4 showing the piston and tool body support members.

FIG. 5 is a sectional view as seen from the line 5-5 showing various passageways in the tool body.

FIG. 6 is a sectional view as seen from the line 6-6 showing various passageways in the tool body.

FIG. 7 is a detailed orthogonal view of the castellated gating ring.

FIG. 8 is a schematic diagram showing the various passageways and their interconnection.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein like refer ence numerals are used throughout the several views to indicate like elements of the invention, the air operated hand tool 1 includes a tool body 2. While various body contours are possible, in the preferred embodiment tool body 2 has the elongated cylindrical shape. This contour is intended to facilitate the random positioning of the tool 1 in the operators hand and to allow it to be tightly gripped for manual operation.

Power is provided to the tool 1 by pressurized air which is converted to a usable mechanical form of energy by means of a reciprocating non-rotary piston 20 which is sealably housed in a cylinder 10 in tool body 2. Attached to opposite ends of piston 20 are a first end plate 21 and a second end plate 22.

End plates

21 and 22 are used to hold

seals

23 and 24 in place on piston 20.

Seals

23 and 24 are fashioned of a flexible rubberlike material and are intended to prevent the movement of air from an area of high pressure at one end of the piston 20 to an area of low pressure at the opposite end. In the preferred embodiment, seals 23 and 24 can be removed for replacement by disengaging screws 22a which attach

end plates

21 and 22 to piston 20.

Non-rotating piston 20 reciprocates in opposite drive and return directions in cylinder in response to a pressure differential across its two ends, thus generating mechanical power from the pressurized air. This pressure differential is by the by selective introduction of pressurized air into one end of cylinder 10 and the simultaneous venting of air from the opposite end. A passageway network 32 (shown schematically in FIG. 8) is formed in tool body 2 to direct this flow of air. The detailed structure of passageway network 32 will be described later. The selective control of the air flow in the various passageways is provided by a valve means 85 and a valve control means also to be described later.

The movement of piston in a drive direction drives a tool bit 50 by means of a drive shaft 40 and a chuck assembly 60. Drive shaft 40 is mounted in tool body 2 by means of bearings 41-43 and extends through a cylindrical bore which extends longitudinally and coaxially through piston 20. In the preferred embodiment bearings 41 and 42 are roller bearings and bearing 43 is an oilite type rotational bearing. O-ring 44 provides a seal around drive shaft 40.

To impart the reciprocating motion of piston 20 to drive shaft 40, a series of helical lands 40a and grooves 40b on the surface of drive shaft 40 are utilized as a power train. Lands 40a and grooves 40b engage matching lands 30a and grooves 30b formed in the surface of cylindrical bore 30 which extends through piston 20. As piston 20 moves axially in cylinder 10, lands 30a and grooves 30b bear against the lateral surfaces of lands 40a and grooves 40b on drive shaft 40 to impart a rotational motion to drive shaft 40.

The rotational drive of drive shaft 40 is communicated indirectly to tool bit 50 by means of chuck assembly 60. Chuck assembly 60 consists of a drive portion 61 and a socket portion 62. Both portions are rotatable in tool body 2. In addition, socket portion 62 can move axially with respect to drive portion 61. This axial independence of socket portion 62 from drive portion 61 is provided by means of peg-like guide rails 63 which interconnect drive portion 61 and socket portion 62. These guide rails 63 allow the communication of rota tional movement to socket portions 62 from drive portion 61 while allowing an axial sliding of socket portion 62 without a corresponding axial sliding of drive portion 61. The desirability of this axial independence is related to a valve control means to be described later.

A tool bit 50 is removably inserted into chuck socket portion 62 by means of a socket recess 64 in socket portion 62. The tool bit 50 is held in place in recess 64 by means of a ball-detent device 51 located in socket portion 62. The ball-detent 51 is of a conventional design. While FIG. 2 shows tool bit 50 to be a Phillipstype screwdriver bit, any suitable bit such as a straight edge screwdriver or a nut socket may be used in its place.

Socket portion 62 of chuck 60 is supported in tool body 2 by bearings 62a and 62b. In the preferred em bodiment, bearing 62a is rotational oilite type bearing and bearing 62b is an oilite type thrust bearing. Where desirable, other types of bearings may be used to support socket portion 62.

Rotational movement of drive shaft 40 in one direction is imparted to chuck 60 by means of two cylindrical cup-

roller clutches

71 and 72. Clutch 71 communicates the rotational movement of drive shaft 40 to chuck 60 and clutch 72 communicates the rotational movement of tool body 2 to chuck 60. This is the es sence of the manual operation capability of hand tool 1. Additionally, the clutch 72 holds the chuck 60 against reverse rotation during movement of the piston 20 in the return direction of its reciprocatory movement. By means of

clutches

71 and 72 the tool bit 50 can be rotated either by the power drive of drive shaft 40 or by hand turning of tool body 2.

FIGS. 2 and 3 show the mounting arrangement of

clutches

71 and 72 in tool body 2.

Clutches

71 and 72 are mounted coaxially forming a cylindrical bearing layering, with drive shaft 40 extending through the center of clutch 71. Cylindrical chuck drive portion 61 is mounted between

clutches

71 and 72. Thus clutch 72 is interspaced between tool body 2 and chuck drive portion 61 to communicate rotational movement of tool body 2 to chuck drive portion 61 and clutch 71 is interposed between drive shaft 40 and chuck drive portion 61 to communicate the rotational movement of drive shaft 40 to chuck drive portion 61.

Clutches

71 and 72 each have a drive rotational direction and a non-engaging rotational direction. In the drive rotational direction, a turning of one race of the clutch transmits a rotational motion to the other race of the clutch. In the non-engaging rotational direction, a turning of one race merely free wheels the other race with no motion imparted to the other race. To accomplish the desired manual operation capability of hand tool 1, the drive rotational direction of clutch 71 is opposed to the drive rotational direction of clutch 72. This permits the tool body 2 to drive the tool bit 50 independent of movement of drive shaft 40 and vice versa.

As noted earlier, piston 20 reciprocates axially in cylinder 10 in response to a pressure differential maintained across the two ends of piston 20. The selective flow of air to and from cylinder 10 which is necessary to maintain this pressure differential is accomplished by means of the passageway system 30 shown schematically in FIG. 8. This passageway system is comprised of three

interconnected passageways

31, 32 and 33. The general purpose of passageway 33 is to serve as an air flow distribution point and it contains an air flow control valve which will be described later. The general purpose of passageway 31 is to carry pressurized air from its source to passageway 33 where it is distributed. Passageway 32 is intended to carry pressurized air through tool body 2 to cylinder 10 and to then exhaust air from cylinder 10 through tool body 2 to the outside air.

Passageway 31 is formed by channels or openings in tool body 2 and communicates pressurized air from a conduit 34 to passageway 33. As is shown in FIG. 2, conduit 34 is a flexible hose or similar structure carrying pressurized air to tool body 2 from a pressurized air source (not shown).

Passageway 32 comprises several interconnected portions designated 32i a, 32d, 32e, 32f, 32g and 32h. These passageway portions are shown schematically in FIG. 8 and in their structural positions in FIGS. 2, 4, 5, and 6. Portions 32g and 32d serve to supply pressurized air to one end of piston 20 in cylinder 10 and to simultaneously vent air from the opposite end of piston 20. This provides the pressure differential across piston 20 which is its motivating force. In the preferred embodiment, passageways 32d and 32g consist of hollowed out portions of tool body 2 and a hollow bolt 32g respec tively. The hollow bolt 32g may serve the dual function of providing passageways and also holding various portions of tool body 2 together when assembled. Passageways 32a and 322 communicate between passageway 33 and chamber 3211 which joins with passageway 32fwhich exits from body 2 to the outside air. Chamber 32h is a baffle to the flow of gas through passageways 32a and 32e and thus acts as a muffler chamber. While FIGS. 2 and 8 show exhaust passageway 32f as .a single bore, multiple bores may also be used. In addition, an exhaust line (not shown) could be attached to passageway 32f to carry exhaust gas from the working area. Thus, passageways 32a and 32e vent air out of cylinder 10 through passageway 33 on the exhaust stroke of piston 20.

Passageway 33 is a hollowed out area of body 2 and serves as a common confluence point of passageway 31 and portions of passageway 32. It is the purpose of passageway 33 to house a valve means 85 which selectively directs air flow through the various passageways mentioned. In particular, the valve means is intended to selectively direct pressurized air from supply passageway 31 to either end of cylinder 10 and to simultaneously vent air from the opposite end of cylinder 10 to the at mosphere.

Valve means 85 consists primarily of a reversing spool 81 which is sealably and slidably located within passageway 33. Reversing spool 81 has an uneven contour which forms two circumferential channels 81a and 81b. Surrounding reversing spool 81 is a stacked array of O-rings 82 and castellated gating rings 83 positioned in passageway 33 by spacers 84 (see detail FIG. 7). The O-rings and gating rings are alternately positioned. The openings in the gating rings 83 adjoin

respective passageways

32a, 32g, 31, 32d and 322, where they enter passageway 33. Thus, the openings in the gating rings 83 serve as extensions of the aforementioned passageways. The O-rings 82 serve as barriers between these various passageways. The flow in

passageways

32a, 32g, 31, 32d, and 32e can be selectively joined when the circumferential channels 81a and 81b are in various selected positions. This is possible because channels 81a and 81b are wide enough to extend between any two adjacent gating rings and their associated passageways. Thus, air flowing to one of the gating rings is directed to another gating ring by means of either of channels 8111 or 81b. In this manner, reversing spool 81 serves as an air flow control valve in passageway 33.

Reversing spool 81 has a first and a second position in passageway 33. Its first position is a biased position. Referring to FIG. 8 where reversing spool 81 is shown in its first position, channel 81b communicates pressur ized air from passageway 31 to cylinder 10 by means of passageway 32d and simultaneously channel 81a communicates exhaust air from cylinder 10 through passageways 32g, 32a, 32h and 32]". This flow of air urges piston in its exhaust direction of movement in cylinder 10. When reversing spool 81 is in its second position channels 81a and 81b are in a different location and pressurized air moves into cylinder 10 through the passageways which serve as exhaust passageways when reversing spool 81 was in its first position. This movement of air forces piston 20 in its power stroke direction. It is thus seen that the control of the position of reversing spool 81 in passageway 33 controls the application of power to the hand tool 1.

To control the movement of reversing spool 81 a valve control means 95 is utilized. The two major components of valve control means 95 are an elongated rod 90 which extends through tool body 2 and bears against reversing spool 81 at one of its ends and a helical coil spring 91 which is housed in tool body 2 and bears against the opposite end of reversing spool 81. It is the purpose of helical coil spring 91 to hold reversing spool 81 in its biased first position. Elongated rod 90 extends through tool body 2 from reversing spool 81 to a position adjacent to chuck socket portion 62. Control rod 90 is slideably located within a hollow bolt 93 which also serves to secure portions of tool body 2 together after assembly.

Elongated rod 90 moves in response to axial movement of chuck socket portion 62 and in so doing bears against reversing spool 81 urging it from its biased position to its second position. As was noted earlier, chuck socket portion 62 moves axially when tool bit 50 engages a work piece. Movement of reversing spool 81 varies the position of channels 81a and 81b relative to

passageways

32a, 32g, 31, 32d and 32e thereby chang ing the communication of air flow in the various passageways. Thus by pressing tool bit 50 against a work piece, valve control means 95 is activated and it in turn changes the position of reversing spool 81 to control the flow of pressurized air to and from cylinder 10.

The operation of hand tool 1 can be briefly summarized as follows. When tool bit 50 of the air operated hand tool 1 engages a work piece, pressure is exerted on the tool bit 50. This pressure causes the axial movement of the socket portion 62 of chuck 60. This motion in turn urges an elongated control rod 90 in an axial direction within tool body 2. Attached to elongated control rod 90 is a reversing spool 81 which is part of a valve means 85. The function of valve means 85 is to control the flow of pressurized air which moves a piston to provide power for the hand tool 1. Pressurized air which enters the tool body 2 through a flexible hose 34 and then through a passageway 31, is directed by reversing spool 81 through selected portions of passageway system 30 to and from piston cylinder 10. This movement of pressurized air causes a pressure differential across piston 20 which in turn urges the piston in a power direction.

As the piston 20 moves in this power direction, it imparts its axial movement to a drive shaft 40 which extends through piston 20. The axial movement of piston 20 imparts rotational motion to drive shaft 40 by means of matching sets of lands and grooves 30a30b and 40a40b which form a power train between piston 20 and drive shaft 40. Thus, as piston 20 moves in cylinder 10 on its power stroke, it causes drive shaft 40 to rotate. The rotation of drive shaft 40 is communicated to a chuck which holds tool bit 50. Drive shaft 40 is operatively connected to chuck 60 by means of a cylindrical cup roller clutch 71.

When piston 20 reaches the ends of its stroke in cylinder 10, the motion of drive shaft 40 ceases and the tool bit 50 is no longer turned by the application of pressurized air. If the workpiece is only partially driven, pressure thereon is relieved, by easing pressure of the tool against the workpiece sufficiently to impart relative movement to the reversing spool 81 to cause the piston 20 to partake of return movement to the opposite end of the cylinder 10. During this movement of the piston 20, the tool bit 50 is held against reverse rotation by the clutch 72. The reversing operation may be repeated until the workpiece is seated. When the workpiece being acted upon by tool bit 50 has been properly seated in place, the function of the hand tool 1 is completed. However, if the limited torque provided by hand tool 1 has been insufficient to properly seat the workpiece being acted upon, the hand tool 1 may be used as a manually operated tool. This is accomplished by merely rotating the tool body 2 while the tool bit 50 is still engaged in the workpiece. The hand rotation of tool body 2 engages a second cylindrical cup roller clutch 72 which is operatively connected to chuck 60.

Since the rotational direction of cup roller clutch 72 is opposite that of clutch 71, the power rotation of chuck 60 by drive shaft 40 is not communicated to tool body After the proper amount of hand turning has been imparted to the workpiece, the hand tool 1 is disengaged from the workpiece by withdrawing tool bit 50. This releases the pressure on elongated control rod 90 which allows the reversing spool 81 to return to its biased position. In this biased position, the communication of flow between the various passageways causes pressurized air to flow into cylinder in such a way as to urge piston in an exhaust direction which returns it to its starting position. Piston 20 then is maintained in this position by the application of pressurized air until the tool bit 50 again engages work which will then restart the cycle by urging reversing spool 81 from its biased position.

What is claimed is:

1. An air-operated hand tool, which is also capable of manual operation, having a rotary output, said tool comprising:

a. a tool body;

b. means defining a hollow cylinder within said tool body;

c. a piston sealably located in said cylinder and mounted for reciprocal movement in said cylinder, said movement having a power direction and an exhaust direction; said piston having opposed first and second ends and having a longitudinally extending cylindrical bore extending axially through said piston between said first and second ends, said piston being moveable in said cylinder when subjccted to air pressure on one end different from the air pressure on the second end;

d. air conduit means for directing pressurized air flow from a source to said cylinder and for venting air from said cylinder to cause movement of said piston;

e. drive shaft having a generally cylindrical outer surface and extending coaxially through said longitudinal bore in said piston, said drive shaft being rotatably moveable;

f. power train means for converting reciprocatory motion of said piston into rotary motion of said drive shaft;

g. tool bit for engaging a work piece;

h. rotatable chuck means carried by said body for holding said tool bit in axial alignment with said drive shaft;

. power drive clutch means for operatively connecting said drive shaft with said chuck means to permit power rotation of said tool bit; and

j. manual drive clutch means for operatively connecting said tool body with said chuck means to thereby permit the tool bit to be rotated by manual rotation of said too] body.

2. The air-operated hand tool of claim 1 wherein said air conduit means comprise means for defining a first, second and third passageway; said first passageway directing pressurized air flow from a source to said third passageway; said third passageway placing certain of said second passageway portions in communication with one another and in communication with said first passageway; said second passageway comprising a plurality of interconnectable passageway portions for directing pressurized air flow to said cylinder from said third passageway and for venting air from said cylinder.

3. The air-operated hand tool of claim 2 wherein said power train means comprise a first helical channel formed in the cylindrical surface of said drive shaft forming a first combination of lands and grooves and a second helical channel formed in the surface of the longitudinal bore in said piston forming a second combination of lands and grooves; said first combination operatively engageable with said second combination to urge said drive shaft into rotational movement in response to axial movement of said piston.

4. The air-operated hand tool of claim 3 wherein said chuck means comprise a socket portion rotatable and slideable in said tool body and a drive portion rotatable in said tool body; said socket portion engageable with said tool bit and rotatably connected with said drive portion such that rotation of said drive portion operatively rotates said socket portion; said socket portion slideably moveable in said tool body in response to pressure applied to said tool bit.

5. The air-operated hand tool of claim 4 wherein said power drive clutch means comprise a cylindrical cuproller clutch for operatively connecting said drive shaft with said chuck drive portion to transmit the rotational movement of said drive shaft to said chuck drive portion; said power drive clutch having a drive rotational direction and a non-engaging rotational direction.

6. The air-operated hand tool of claim 5 wherein said manual drive clutch means comprise a cylindrical cuproller clutch for operatively connecting said tool body with said clutch drive portion to transmit the rotational movement of said tool body to said chuck drive portion; said manual drive clutch having a drive rotational direction and a non-engaging rotational direction, said drive rotational direction opposed to the drive rotational direction of said power drive clutch such that rotation of said drive shaft is not transmitted to said tool body.

7. The air-operated hand tool of claim 6 wherein valve means are provided for selectively controlling the flow of pressurized air from said first passageway into said second passageway and for selectively placing portions of said second passageway in communication with certain other portions to control the reciprocation of said piston; said valve means comprising a reversing spool sealably and slideably located within said third passageway; said reversing spool having a first and second position, said first position being a biased position which permits said reversing spool to join the flow in said first and second passageways and portions thereof such that said piston is urged in said exhaust direction; said second position permitting said reversing spool to join the flow in said first and second passageways and portions thereof such that said piston is urged in said power direction.

8. The air-operated hand tool of claim 7 including a valve control means for urging said valve means from said biased first position to said second position in response to said tool bit being pressed against said work 10 socket portion; said rod urging said valve from said first position to said second position in response to axial movement of said chuck socket portion caused by prespiece; said control means comprising an elongated rod 5 Sure exfirted upon said tool bit slideably extending from said valve to said chuck UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT I 3 866 493 DATED .Feb. 18, 1975.

INVENT0R(5) 1 CHESTER A. RINGERUD it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: Column 3, Line 5 "by th by" should be: --created by the- Column 4, Line 58 "32 i a,." should be --'-32a- Attest:

Signed and sealed this 13th .day of May 1.9 75.

(SEAL) I c MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks

Claims

1. An air-operated hand tool, which is also capable of manual operation, having a rotary output, said tool comprising: a. a tool body; b. means defining a hollow cylinder within said tool body; c. a piston sealably located in said cylinder and mounted for reciprocal movement in said cylinder, said movement having a power direction and an exhaust direction; said piston having opposed first and second ends and having a longitudinally extending cylindrical bore extending axially through said piston between said first and second ends, said piston being moveable in said cylinder when subjected to air pressure on one end different from the air pressure on the second end; d. air conduit means for directing pressurized air flow from a source to said cylinder and for venting air from said cylinder to cause movement of said piston; e. drive shaft having a generally cylindrical outer surface and extending coaxially through said longitudinal bore in said piston, said drive shaft being rotatably moveable; f. power train means for converting reciprocatory motion of said piston into rotary motion of said drive shaft; g. tool bit for engaging a work piece; h. rotatable chuck means carried by said body for holding said tool bit in axial alignment with said drive shaft; i. power drive clutch means for operatively connecting said drive shaft with said chuck means to permit power rotation of said tool bit; and j. manual drive clutch means for operatively connecting said tool body with said chuck means to thereby permit the tool bit to be rotated by manual rotation of said tool body.

5. The air-operated hand tool of claim 4 wherein said power drive clutch means comprise a cylindrical cup-roller clutch for operatively connecting said drive shaft with said chuck drive portion to transmit the rotational movement of said drive shaft to said chuck drive portion; said power drive clutch having a drive rotational direction and a non-engaging rotational direction.

6. The air-operated hand tool of claim 5 wherein said manual drive clutch means comprise a cylindrical cup-roller clutch for operatively connecting said tool body with said clutch drive portion to transmit the rotational movement of said tool body to said chuck drive portion; said manual drive clutch having a drive rotational direction and a non-engaging rotational direction, said drive rotational direction opposed to the drive rotational direction of said power drive clutch such that rotation of said drive shaft is not transmitted to said tool body.

8. The air-operated hand tool of claim 7 including a valve control means for urging said valve means from said biased first position to said second position in response to said tool bit being pressed against said work piece; said control means comprising an elongated rod slideably extending from said valve to said chuck socket portion; said rod urging said valve from said first position to said second position in response to axial movement of said chuck socket portion caused by pressure exerted upon said tool bit.