US2326347A - Impact tool - Google Patents

Description

Aug. 10, 1943. F. P. FORSS 2,326,347

IMPACT TOOL /illl INVENTOR. F/r/f/of A Fo/Pss W A BY @wam A TTORNEY.

F. P. FORSS IMPACT TOOL Filed Oct. 9, 1941 4 Sheecs-Sheet 5 IN VEN TOR.

F/P/r/f/o/f ,0, ,rags-S ATTORNEY.

Aug l0, 1943. F. P. FoRss 2,325,347

IMPACT TOOL Filed oct. 9, 1941 4 sheets-sheet 4 l! 1 f5 7K ./4/

A TTORNEY.

Patented Aug. 10, 1943 nvrPAc'r 'rooL Frithioi P. Forss, Aurora, ill., assignor to Indei pendent Pneumatic Tool Company, Chicago, Ill., a corporation of Delaware Application october 9, 1941, serial No. 414,228

ze claims. (c1. naz-4305) This invention relates to improvements in portable hand-held, self-contained motor driven impact tools for screwing up and removing nuts andv bolts by power.

The principal object and purpose of my invention is to provide a relatively light, but powerful impact tool of an extremely strong and sturdy construction throughout, designed for setting and removing in a minimum of time relatively large nuts and bolts up to 11A" bolt size asv employed in railroad shops, ship yards, constructors, automotive plants and other heavy industries, the tool having suiiicient power for driving larger size nuts and bolts in some kinds of work where the torsion requirements are not in the extreme.

A further object of the invention is to provide a tool in which the nut driving and nut removing operations are of the impact type, as distinguished from the ordinary power wrench, whereby no torque is transmitted to the operator in the work in a screwing up operation or loosening a tight or rusted nut in an unscrewing or removing operation.

A further object of the invention is to provide the impact members and the anvil jaws of relatively heavy section and slidably mount the impact members in slots in the hammer element for rectilinear movement whereby the impact members may be provided with relatively wide side surfaces substantially co-extensive with the side surfaces of the slots and the jaws to respectively support the impact members in the slots and have driving and impact engagement with the jaws throughout substantially the full length thereof.

A further object of the invention is to provide momentum means acting independently of the hammer element for automatically releasing the impact members from the anvil jaws following each blow delivering impact thereon by positively moving the impact members out of the orbital path of the jaws.

A further object of the invention is to provide said momentum means with recesses to receive and position the impact members in the orbital path of the jaws and cam means to move the impact members out of the path of the jaws in the rotation of the momentum means relatively to the hammer,

A further object of the invention is to provide coacting means between the hammer and the momentum means to impart rotation to the latter and to control the movement thereof in positionving the recesses and the cam means with respect to the impactmembers.

A further object of the invention is to utilize the co-acting elements on the hammer and the momentum means as a limiting stop to prevent overrunning of the hammer by the momentum means on the release of the impact members and retain the recesses and the cam means in proper positions with respect to the impact members and the anvil jaws..

A further object of the invention is to provide means for setting said co-acting elements for either direction of rotation.

And a further object of the invention is to provide a safety brake to stop the rotation of the motor when the throttle valve is closed and thereby give the operator complete control over the free spinning of a loose nut when removing the same to prevent the nut flying off the bolt on being unscrewed therefrom.

The invention consists further in the features hereinafter described and claimed.

In the accompanying drawings illustrating one embodiment of my invention- Fig. l is a longitudinal sectional view with parts in elevation of my improved impact tool;

Figs. 2 and 2A are similar sectional views of the tool on a larger scale than that employed in Fig. 1; Fig. 2 constituting a section of the lower portion of the tool containing the impact clutch and Fig. 2A beinga section of theupper portion.

of the tool containing the driving motor and control valves therefor, one section being a continuation of another from the dividing line A-A between them, the casing for the reversing valve which would appear in these views and 'also in Fig. 1 being omitted for clarity of illustration;

Fig. 3 is a. transversey sectional view taken on line 3-3 of Fig. 1 with the impact members in elevation and shown in driving and impact blow with parts in elevation and showing the cam ring y lifted to raise the stop b ar above the shorter lugs on the cam ring;

Fig. 9 is a transverse sectional view taken through the motor section of the tool on line 9-9 of Fig. 1;

Fig. 10 is a perspective View of the hammer element;

Fig. 11 is a similar view of the anvil element;

Fig. 12 is a similar view of the cam ring;

Fig. 13 is a fragmentary longitudinal sectional view with parts in elevation of the reversing valve to be herein described;

Fig. 14 is a transverse sectional view taken on line III-I4 of Fig. 1 to show the porting on the exhaust side of the tool;

Fig. 15 is a sectional view showing the portion 4 of the reversing valve in Fig. 14 turned to its reversing position;

Fig. 16 is a sectional view of the operating valve for the brake disc on a larger scale than employed in Figs. 1 and 2A; and

Fig. 17 is a diagrammatic view to be later referred to.

While the tool may be driven by any preferred form of motor, yet I have shown the tool in the present disclosure equipped with a pneumatically operated reversible motor of the rotary type having a revoluble rotor I and a surrounding stationary cylinder bushing 2. These parts are housed within the cylinder case 3 of the outer casing of the tool as shown in Figs. 1 and 9. I'he cylinder bushing 2 is held against rotation in the tool case by being keyed throughout its length to the cylinder case 3 and contains the rotor I in eccentric relation to the bushing 2 as shown in Figs, 9 and 14. It will be noted from these figures that the rotor I has peripheral contact with the inner cylindrical surface of the cylinder bushing 2 at one point in its circumference to divide the chamber formed by the cylinder bushing into high and low pressure sections, respectively, as in motor, devices of this character.'

Slidable blades 4, 4 are carried by the rotor I in radial slots 5, 5 therein and these slots are supplied at their bottom portions with the compressed air or other pressure fluid furnished to the tool to hold the outer edges of the blades at the proper points in contact with the inner cylindrical surface of the cylinder bushing 2. The porting arrangement for accomplishing this result is not shown, constituting no part of my present invention.

The trunnions or shaft extensions 6, 'I at the opposite ends of the rotor I are journalled in the tool assembly and extend through the upper and the lower centerplates 8, 9 which close the opposite ends of the cylinder bushing 2 as shown in Fig. 1. The centerplates 8, 9 are mounted in the cylinder case 3 and are held against rotation by dowel pins or otherwise. The shaft sections B, I of the rotor are journalled in anti-friction bearings ID, II supported in the tool assembly at the centerplates 8 and 9, respectively. 'Ihese bearings are of extremely heavy size.xparticular1y the escasa? lower bearing II which receives the more severe service being next' adjacent to the impact clutch mechanism to be presently described'. The lower shaft 'I has direct connection with the hammering element of said clutch.

The upper shaft 6 of the rotor is equipped with a governor valve to automatically control the amount of pressure fluid supplied to the motor in the operation of the tool in accordance with iis speed of rotation. 'I'his feature forms no part of my present invention, but as shown in Fig. 2A comprises generally an axially movable valve member I2 which controls a port I3 in a. bushing I4 xed in the handle section I5 of the tool in crossing relation to its main presure fluid supply passage I6. The latter connects into the bushing I4 through a port I'I therein beyond the limit of outward movement of the valve member I2. This member is moved inwardly by the live air pressure acting on its upper surface and is given outward movement to partially close the port I3 by pivoted weights I8, I8 carried by and rotating with the shaft section 6. These weights swing outwardly from the axis of the rotor in response to centrifugal force as the motor speed accelerates and move the valve member I2 to partially close the port I3 to reduce the amount of air pressure supplied to the motor when running at free speed. When under load, as when screwing up or unscrewing a nut or a bolt, the centrifugal force decreases and the fluid pressure on the valve member I2 moves it towards the shaft 6 to open the port I3 and supply a greater volume of live air to the motor to increase its driving power.

The handle section I5, which may be of the grip type as shown, is secured to the upper end tion I5 between its main supply passage I6 and the nipple 20. Said valve is movable to open position through a trigger element 22 pivoted on the handle section I5 and engageable by the operator from the outer side of the handle.

When the throttle valve 2| is unseated com- I pressed air is supplied to the tool motor through the passage I6 and the other passages connected therewith in the handle and cylinder sections I5 and 3, respectively. One of these passages in the handle section is shown at 23 in Fig. 2A. This passage surrounds the bushing I4 and connects with the port I3 therein. The passage 23 connects with a passage 24 'in the cylinder case 3 at one side of the reversing valve bushing 25 as shown in Fig. 9. When the reversing valve 26 in this bushing is turned to the full line position shown in Fig. 9, the ports 21, 2s in the bushing 25 connect the passage 24 with a passage 29 in the cylinder case 3 and leading to one or more ports 30 in the cylinder bushing 2. These ports 30 are spaced along the length of the cylinder bushing 2 and supply live air to the rotor I on the now high pressure side of the motor. The rotor I is now rotated in a clock-wise direction as indicated by the arrow a in Fig. 9-and the tool operates to screw up a bolt or nut as the case may be.

The exhaust from the motor at this time is from the low pressure side of the rotor through one or more ports 3| in the cylinder bushing 2 and connected with a. space 32 between the cylinder bushing and the cylinder case 3 at the side of the ports 3|. The exhaust ports 3| are distributed along the length of the Icylinder bushing 2 and the space 32 connects with an exhaust passage 33 in the cylinder case 3 as shown in Fig. 14. At this location the reversing valve bushing 25 has ports 34, 35, the former being connected with the passage 33 and the other being connected with the main exhaust outlet 36 of the tool in the cylinder case 3 as shown in Fig. 14. .At this port, the reversing valve 26 has a solid body portion 31 and a cut-away portion providing a recess 38 which when the valve is in the position shown in-full lines in Figs. 9 and 14 connects the exhaust passage 33 with the main exhaust outlet 36. At this-time the interior of the cylinder bushing 2 on the low pressure side of the rotor is also connected with the exhaust outlet 36 through ports 39 in the cylinder bushing 2 and a passage 40 in the cylinder case 3 as shown in Fig. 9. The reversing valve bushing 25 has ports 4|, 42 which connect the passage 40 with a passage 43 in the cylinder case 3 leading t'o the main exhaust outlet 36. The web portion 44 of the reversing valve 26 at the ports 4|, 42 divides them from the ports 21, 23 which are now supplying pressure fluid to the high pressure side of the motor to rotate it in a screwing up direction.

It will be noted that the ports 30 and 39 in the cylinder bushing 2 are on opposite sides of its line of contact with the rotor l. Hence, when the rotor l is being rotated to drive a bolt or nut, the ports 30 are the inlet ports on the high pressure side of the motor, while the ports 39 are on the exhaust side. The reverse relation exists when the reversing valvel26 is turned to reverse the direction of rotation of the motor as will be presently described. The ports 39 have the same arrangement and longitudinal spacing as the ports 30.

The cylinder bushing 2 has a second set of ports 45 Asimilar to the ports 3|. 'Ihe ports .45 are on the side of the cylinder bushing 2 oppo' site to the ports 3| and connect with a space 32a opposite to the space 32 and similar thereto. The space 32a is on the exhaust side of the motor when running in reverse and connects with an exhaust passage 46 in the cylinder case 3 as shown in Fig. 14. When the rotor is running in a screwing up direction the passage 46 is closed off from the exhaust 36 by the solid body portion 31 of the reversing valve 26 closing a port 41 in the valve bushing 25 and connected with the passage 46. The space 32a is separatedfrom the space 32 by rib formations on the outer side of the cylinder bushing 2 about the boundaries of the respective spaces. The axial ribs are marked b and c in Figs. 9 and 14.

When the reversing valve 26 is turned to the dotted line position d in Fig. 9 the inlet passage 24 is connected with the passage 49 and the ports 39 and pressure fluid is now supplied to the opposite side of the rotor to rotate the rotor in reverse direction or in a direction to unscrew a nut or bolt. At this time the motor exhausts through ports 45, space 32a, passage 46, ports 41 and 35 and main outlet 36 as indicated in Fig. 15. The interior of the cylinder 2 on the exhaust side of the motor also exhausts through ports 30, passage 29, ports Zilandv 42 and exhaust'v passage 43 as seen from Fig. 9. The space 32 and the passage 33 which are now on the high pressure side of the motor are closed to the exhaust ouuet as by the solid body portion 31 of the reversing valve 26 closing the port 34 as shown in Fig. 15.

The reversing valve 26 is in the form of a turning plug as best shown in Fig. 13. The web section 44 is between the solid body section 31 4 at thelower end of the plug and a circular top section 48. The sections 31 and 48 rotatably mount the plug in the bushing 25 and the upper end of the plug is provided with a shaft-like extension 49 to receive a manually operable turning lever 50. The latter is clamped to the plug for turning it from the outer side of the tool case. A spring pressed detent 5| carried by the handle section l5 and engageable with the shaft section 49 holds the valve plug 26 in either of its `\operative positions, that is, one for a clockwise rotation of the rotor and the other for a reverse rotation. For assembling and disassembling purposes the valve plug 26 and its extension 69 are made separate being connected by a tongue and slot arrangement as indicated in dotted lines in Fig. 13.

The impact clutch mechanism is located within the lowerl portion 52 of the tool casing below the driving motor, the casing 52 being secured to the lower end of they motor case 3 in any preferable manner as by bolts 53. The impact clutch comprises axially alined hammer and anvil elements 54, 55 as clearly shown in Figs. 2, 10 and 11.

The hammer element 54 is preferably a solid, one-piece drop forging of metal of the desired quality and is generally cylindrical in form as shown in Fig. 10. The upper cylindrical end portion 56 of the hammer element fits about and is connected to the lower end portion of the lower shaft section 1 of the rotor to be driven therebyas shown in Fig. 2. As indicated in Figs. 2 and 10, the hammer element 54 has a heavy,

splined connection with the shaft section 1 as at 51 to provide a direct drive connection between them.

The anvil element is also a one-piece drop forging of similar metal and, as shown in Fig. 11, comprises an upper or head portion 58 provided with a pair of upwardly extending jaws 59, 59 of relatively heavy section. These jaws are integral with the head section and are disposed in diametrically spaced relation as detailed in Fig. 11. The jaws 59 fit about the lower cylindrical body portion 60 of the hammer element 54 with sufficient clearance to permit free relative rotation of the hammer and anvil elements when disconnected by the impact members to be presently described. The anvil element 55 has a lower shaft or spindle portion 6| also integral with the head section 58 and rotatably mounted' in a bearing bushing 62 fitted against rotation in the extreme lower part of the tool casing 52 as shown in Figs. 1 and 2.

The extreme lower end portion 63 of the anvil spindle 6| extends out of the tool case 52 when the parts are assembled and is preferably made non-.circular in shape to receive and rotate a nut or bolt head engaging socket member 64 as shown in Fig. 2. The connection between the lower end of the spindle 6| and the socket 64 is releasableA comprising in the embodiment shown a cross-pin 65 fitting within line openings 66, 61 in the respective parts and normally held in its connecting relation by a split retainer ring 68 applied about the socket in the region of the pin as shown in Figs. 1 and 2. The connection referred to enables sockets of different nut or bolt sizes to be used with the tool. the socket engaging end 63 of the anvil spindle Bl is made to t all standard impact type sockets up to 1" square drive size.

As shown in Fig. 2, thc hammer element 54 bears against the anvil element 55 between its jaws 59. To provide a revoluble connection for the parts the lower end face 69 of the hammer elementis made radially fiat and circular and fits a complementary face on the upper surface of the anvil element at the base of the jaws 59. Interposed between the parts at this point of contact is a centering pin 1I. is cylindrical and fits within alined axial bores 12, 13 in the hammer and the anvil elements 54, 55, respectively, as shown in Fig. 2. The member 1I has an enlarged portion 14 in the hammer bore 13 to seat the pin between the hammer and anvil elements and to project the upper smaller end of the pin into the path of the impact elements 15, 15 with which the hammer 54 is provided. In this way the pin 1I provides a limiting stop for the impact members 15, the latter having notches 1|a at their lower inner edges to receive the pin 1| to retain as much mass as possible for the impact members for blow delivery purposes. The pin 1i also prevents the impact members coming into contact when moved inward to their fullest extent and hence, no opportunity is afforded for the impact members tobind or stick together.

This member In practice,

of rotationzs imparted to the anvil"`55 when the. impact ,members engage the surfaces- 59h ofthe jaws.

The y"cam ring-heretofore referred to is shown at 19.` This'ring is momentum operated and acts automatically in the operation of the tool to slide the impact members 15 backwardly into the slots 16 to release the impact members from the anviljaws 59 immediately following each hannner, blow of the impact members on the jaws. This occurs when the free turningv of the anvil by the rotating hammer is resisted by the nut or bolt in a screwing up or an unscrewing operation. The cam ring 19 has a oating or over-running mounting about the hammer 54 between the upper ends of the jaws 59 and an outwardly projectingl annular flange 80 on the hammer 54 above the slots 16. An. annular bearing member 52a in the housing 52 gives the ring 19 this support and position (See Fig. 2).

The cam ring 19 is also a drop forging, in onepiece of metal and comprises an annular body portion 8| having a circular opening 82 to fit about the cylindric body section 6U of the hammer 54. The cam ring 19 is provided on its inner side with a pair `of circumferentially extending recesses 83, 83 diametrically disposed and joined by arcuate sections 84, 84 of the same diameter as the opening 82. The purpose of the recesses 93 is to allow the impact members 15 to move outf wardly into the orbital path of the anvil jaws The impact members 15 are also drop forgings in the form of solid rectangular blocks of the desired heavy section and blow delivering metal. The impact members 15 are slidably mounted in slots 16, 16 in the hammer element 54, one for each impact member. The slots are radially disposed in respect to the axis of the hammer and constrain the impact members to a linear sliding movement, outwardly in response to centrifugal force and inwardly by the action of the cam ring thereon as presently described. The slots 1B are diametrically disposed and open into the hammer 'bore 12 so that the impact members 15 may be The slots 16 are disposed in the hammer 54 to extend above and below the upper end of the jaws 59 when the parts are assembled as shown in Fig. 2. With this arrangement, the lower body portions 11 of the impact members 15 are positioned to engage the jaws 59 when the impact members project into the orbital path of the jaws, whereas the upper portions 18 of the irnpact members are above the upper ends of the jaws for engagement by the cam ring heretofore referred to. The arrangement described is shown in Fig. 2. The lower body portions 11 of the impact members 15 have substantially flat striking surfaces 15a, 15b on their opposite sides to engage the substantially dat impact receiving surfaces 59a., 59o on the opposite sides of the jaws 59. With the striking and impact receiving surfaces so disposed, it will be seen that the impact members 15 may drive the anvil 55 in opposite directions. The anvil 55 is rotated clock-wise in a screwing `up operation when the impact members 15r engage the jaws at their impact re- `eiving surfaces 59a, whereas a reverse direction sired relationship between the recesses 83 and the impact members 15 and also imparts rotation to the cam ring. As long as the nut or bolt being driven is free to turn, the impact members 15 retain driving engagement with the anvil jaws, being held in that relation by the centrifugal force generated by the rapidly rotating hammer.

When the rotation of the anvil element 55 is arrested as heretofore mentioned, the camiing 19 continues to rotate by its momentum and forces the impact members 15 back into the slots 16 to release the drive of the hammer on the anvil element. This occurs because the cam surfaces 81 of the ring at the ends of the recesses 83 move the impact members 15 out of the rccesses. As the arcuate surfaces 84 of the cam ring pass over the outer ends of the impact members 15 the latter are retained within the outerv circumference of thehammer 54 and the latter is free to be driven by the motor relatively to the anvil 55. This carries the impact members 'l5 past the anvil jaws 59 as will be seen from Fig. 5 and the stopbar 85 picks up the `cam ring 19 to iposition the recesses 83 beyondthe jaws to again receive the impact members on freeing the jaws. The impact members 15 are now moved outwardly by centrifugal force into the spaces between the anvil jaws and the motor now operating at full speed carries the impact members with a striking blow against the side surfaces of the jaws towards which the movement is directed.

The anvil 55 being still held against'rotation by the tightened or previously tightened nut or bolt is partially turned by this blow and the nut or bolt is further tightened or loosened as the case Y may be. At the time of striking or impact, theV members 15 and the hammer 54 come to an abrupt stop. In fact, the impact members 15 heavy rotational hammer blows are struck in rapid succession against the anvil jawsV 59 to eiectively tighten or loosen the nut or bolt depending on the direction of rotation of the tool motor.

The recesses 83 open downwardly through the lower side of the cam ring 19 to t over the upper end portion 18 of the impact members 15. This is shown in Fig. 2. The outer end portions of the impact members at the cam ring are rounded or curved as indicated at e, e in Figs. 3 and 5 for ease in passing over the cam surfaces of the cam ring and the anvil jaws 59. The recesses 83 in the cam ring 19 have the same circumferential extent for systemetrical action on opposite sides of the ring. Y

The anvil jaws 59 are so proportioned and arranged that the hammer 54 may rotate through a full half revolution in moving an impact mem# ber from one jaw to the next in striking a blow. This is due to the fact that the circumferential distance from the impact receiving surface of one jaw 59 in the direction of rotation is approximately 180 to 4the impact receiving surface of the next jaw. This is indicated in the diagram in Fig. 17. Hence, when an impact member 15 is movedby the cam ring to release an anvil jaw as shown in Fig. 5, the hammer 54 in carrying said impact member to the next jaw travels a full half revolution. With this arrangement relatively heavy and solid blows may be delivered to the anvil because of the fact that the hammer may accelerate and come to full speed before delivering its blow. This accleration of the hammer also has the advantage of enabling the hammer to overtake the cam ring to insure having the recesses 83 in the cam ring properly located to receive the impact members as soon as theyV are canied free of the jaws.

The stop bar 86 is carried by the hammer 54 in a cross-slot 88 therein above the slots 16 as best shown in Figs. 2 and 10. The slot 88 extends completely through the hammer body in the same position as the slots 16 and is directly above the same. The slot 88 while it extends above and below the flange 88 terminates at its bottom slightly above the upper surface of the cam ring 19. This positions the bar 86 just above the upper surface of the cam ring and locates its end portions 86a, 86h in the path of a series of upright lugs 89, 98 on the cam ring and projecting above the same. The lugs 89, 98 are diametrically and .alternately arranged with a 45 degree spacing between them as shown in Fig. 4. The lugs 89 are slightly longer than the lugs 98. This terminates the upper ends of the lugs 98 just below the flange 88 on the hammer. The lugs 89 extend to about the upper surface of this ange, the inner upper edges of said lugs being recessed as at 98a to accommodate the flange 88 as shown in Fig. 12. l

The bar 86 drives the cam ring 19 through the longer lugs 89. the shorter lugs 98 serving as stops to prevent overrunning of the cam ring when acting under momentum. When the tool is rotated forwardly, the bar acts on one side of the lugs 89 as shown in Fig. 4. When rotating the tool in reverse the bar drives through the opposite sides of the lugs 89. To adjust the bar 86 to operate on either side of the lugs 89, it is necessary to shift the bar with respect to the lugs. The shifting mechanism is automatic in action and is constructed as follows:

Surrounding the hammer 54 in the region of the bar 86 is a shifter ring 9|. This ring :lits over the opposite ends of the bar 86 and has an inwardly directed annular flange 92. The latter, as shown in Fig. 8, extends under the outer end portions of the bar 86 and lifts the bar when the ring 9| is raised axially upward as illustrated in Fig. 8. This movement carries the bar 86 above the upper ends of the shorter lugs 98 and permits the bar to be rotated with the hammer over the shorter lugs to operate on the desired operative sides of the longerlugs 89. Hence, for a forward or screwing up rotation the bar 86 engages the side surfaces 89a of the lugs 89 as shown in Fig. 4, while for a reverse rotationthe bar 86 engages the opposite surfaces 89h of the lugs 89. In a reverse rotation of the tool the impact members 15 drive against the impact receiving surfaces 59h and the clutch releases through the reverse action of the cam ring 19. i

The shifter ring 9| holds the bar 89 against endwise displacement, the outer annular wall 93 of said ring being over the outer ends of the bar as shown in Figs. 1, 2, 4, 5 and 8. To assemble the parts, the shifter ring 9| has a slot 94 in its annular wall 93 to pass the bar 89 when the slot and the bar are brought to register. Thisslot is shown in Figs. 4 and 6. A split spring band 95 is located within the shifter ring 9| to partially close the slot 94 to retain the bar 89 within the ring. At least one end of the band 95 is bent at right angles to stop the ends of the band at the slot 95 and to also permit the band being pulled out or threaded into the slot when applying or removing the band.

The lifting mechanism for the shifter ring 9| comprises a plurality of circumferentially spaced piston element 96, 96 as shown in Figs. 1, 2, 7 and 8. The pistons 96 are mounted in downwardly directed cylinders 91 provided on the lower centerplate 9 of the motor assembly. The ring 9| is secured to the piston elements 96 by screws 98, the latter extending through holes 99, 99 in the top wall |88 of the shifter ring. The heads of the screws 98 engage against the under side of the wall |88 and raise the shifter ring 9| when the pistons 96 are moved upwardly. When the shifter ring is lowered as shown in Fig. 2, it may rest on a flange 52h provided in the casing section 52.

Each cylinder 91 is provided with a pair of ports |8|, |82. These ports are axially spaced, the port |8| being adjacent to the upper end of the cylinder and the port |82 being adjacent to the lower end of the cylinder. The lower port |82 connects with a live air channel |83 formed in the cylinder case 3 on the outer side of the centerplate 9 as shown in Figs. 1 and 2. A passage |84 in the cylinder case 3 connects the channel |83 with a space |85 between the cylinder bushing 2 and the cylinder case 3 as shown in Figs. l and 9.v This space extends to adjacent the upper end of the cylinder bushing 2 and is connected by a passage in the case 3 with a passage |01 inthe handle vsection I5. sage |01 has direct connection with the live air supply passage l0 in the handle as shown in Figs. 1 and 2A. With this arrangement when the throttle valve 2l is unseated, live air is supplied to the cylinders 91 through the lower ports |02 and the pistons 99 are moved upwardly to lift the bar v09. The pistons 99 have lower `pressure areas |00 for this action as shown in Figs. 1, 2 and 8. The pistons 9 5 may be moved upwardly because the upper ends of the cylinders 91 are normally open to the exhaust on the low pressure side of the motor through the upper ports |0| and the connected arcuate slot |09 in the upper surface of the centerplate 9 within the diameter of the cylinder bushing 2 as shown in Fig. 9. This slot extends on opposite sides of the center line of the rotor I, and" hence has portions on the low and the high pressure sides of the motor in either direction of rotation. With this arrangement, while the cylinders 91 may exhaust in the upward movement of the pistons 96, live air may also enter into the upper ends of the cylinders from the high pressure side of the motor and act on the larger upper pressure areas of the pistons 96 to immediately move the pistons 96 downwardly to lower the ring 9| to its normal position. This action occurs rapidly on each unseating of the throttle valve 2| and the position of the bar 05 is not changed as to the lugs on the cam ring unless the motor is set for a reverse rotation. 'I'he upper ports IOI are connected with the slot |09 by a channel ||0 about the outer edge of the centerplate 9 as shown in Fig. 2. This channel like the channel |03, extends to all of the cylinders 91 with which the device'is provided. They are three in number in the embodiment disclosed as will be seen from Fig. 7.

The brake device to prevent over-running or spinning of the rotor I when the power is cut off, comprises a brake disc III overlying the upper wall |00 of the shifter ring 9| and seated on a shoulder ||2 on the hammer 54 at the base of its upper cylindrical portion 56 as clearly shown in Fig. 2. This disc III is held from rotation with the hammer 54 by the pistons 96 and a plunger ||3. The pistons 90 extend through openings in the disc as shown. The plunger |I3 is slidably mounted above the disc III in a cylinder I.|4 in the centerplate 9 as shown in Figs. 1,12y and 8. The plunger I|3 has a reduced lower end portion ||5` to extend downwardly through an opening I I6 in the disc |II to hold the disc against rotation and to provide a shoulder to press the disc against its seat II2 on the hammer 54. The shift ring 9| has a hole I|1 to receive the lower end of the plunger II 3 when the ring is lifted. This allows for close spacing of the parts for compactness in construction.

The action of the plunger I |3 is controlled automaticallyvby a valve IIB shown in-Figs. 1, 2A

and 8, but detailed in Fig. 16. This valve is in the portion of the cylinder bushing 2 at one of the rib sections b. The lower end of the passage |23 is connected with the cylinder ||4 by a port |24 in the lower centerplate Sas shown in Figs. l and 8. The valve member ||8 is provided on its outer side with upper and lower annular channels |25, |28, respectively. The bushing ||9 is provided with an upper port |21 which connects with the upper channel |25 when the valve member II8 is in its uppermost position as shown in Figs. 2A and 16. Port |21 connects with a live air supply passage |28 through a port |29 both in the handle section I5 as shown. It will be noted that the passage |28 is connected into the air supply for the tool on the advance side of the throttle valve 2|. Hence, as soon as the tool is connected to the air supply live air is immediately conveyed'to the valve member I|8 through the passage I 28 and ports |29 and 21. This subjects the pressure areas |30, I3| on the valve to live air pressure and the valve member II8 is moved upwardly to register its port |32 with the channel |25. Port |32 connects with the bore |20 in the valve member and pressure fluid is now supplied to the cylinder |I4 through the passage |23. The plunger 3 is now forced downwardly by live air pressure and passes the disc I I against the seat |I2 on the hammer 54 to stop its rotation. s

The upward movement of the valve member I8 is stopped by contact of the upper end of said valve member II8 with a shoulder |33 about a port |34 in the handle section I 5 above the valve bushing ||9. The port |34 connects with the supply passage I6 in the handle I5 and subjects the upper closed end ofthe valve member ||8 to live air pressure on opening the throttle valve 2 I. As the upper end of the valve has a greater pressure area than the shoulders |30, I3I, the valve member I|8 is moved downwardly as soon as the throttle valve is unseated. This moves the port |32 out of register with the channel |25 and carries said port into register with the channel |26. The bore |20 of the valve member ||8 is now open to the exhaust ports which are provided for the valve and the pressure of the plunger ||3 on the disc |||y is released freeing the `motor of the brake.

The exhaust ports referred to comprise ports |35, |36 in valve bushing 9 and a registering port |31 in the handle section I5 as shown in Fig. 16.

'Ihe statements of operation employed throughout the foregoing description of the structure of the tool and its parts are believed to present a full description of the operation and use of the tool. summarized briefly, however, the operation of the tool is as follows:

To screw up a nut or a bolt to a tight seat, f

the tool is held in the hands of the operator by the handle-section |5 and a dead handle, if one is provided at the side of the tool, and its socket E4 is applied over the nut or bolt to be driven indicated at I 38 in Fig. 1. The motor is then set in operation by opening the throttle valve 2| to supply compressed air to the motor. The reversing valve 26.at this time is set towards the right to rotate the motor in a forward or screwing up direction. On opening the throttle valve 2|, the live air acts on the brake controlling valve ||8 to automatically relieve the motor of the holding effect of the brake disc ||I and the tool motor rotates to speed. The hammer 54 being directly connected with rotor lI rotates at the same speed as the rotor and the impact members I are moved by centrifugal force into the orbital path of the anvil jaws 59. As soon as the impact members engage the jaws 59 the anvil element 55 is connected to the hammer and the two rotate in unison to screw up the nut or bolt to its seat. The cam ring 'I9 is picked up by the rotatingr hammer 54 through the ystop bar 8'6 and the lugs 89 and rotation is imparted to the cam ring with the outer ends of the impact members 'I5 within the recesses 83 of the ring. 'I'his connection is retained until the nut or bolt seats against the Work, whereupon' further rotation of the anvil element 551s arrested and the cam ring 'I9 continues to rotate by its momentum to withdraw the impact members 'I5 from the anvil jaws 59. This releases the connection between the hammer and the anvil elements I and the hammer is free to be rotated by the tool motor. Inthis relative rotation the motor speeds up, catching up with the cam ring and setting the recesses 83 to vagain receive the impact members as soon as they are carried past the anvil jaws. Centrifugal force again operates to slide the impact members I5 into the spaces between the anvil jaws and a positive, direct heavy rotational hammer blow is struck by the impact members against the anvil jaws next to be engaged. This turns the anvil element with suicient torque to further tighten up the engaged nut or bolt. The operation repeats as long as the tool remains engaged with the nut or bolt and a series of direct, positive heavy rotational hammer blows are imparted in rapid succession against the anvil jaws to adequately tighten the nut or bolt in the continued rotation of the tool motor. When the nut or bolt has been tightened to the extent desired, the tool is removed from the work and engaged with the next bolt or nut to be driven.

For a reverse rotation, as when unscrewing a tight or rusted bolt or nut, the reversing valve 26 is set towards the left before applying the socket 54 of the tool to the selected -nut or bolt. 'I'he throttle valve 2| is then unseated as before and the impact members 'I5 connect the anvil 55 with the rotating hammer 54. If the nut or bolt is so tight that it does not respond immediately to the torque of the tool motor, the impact members are withdrawn from the anvil jaws by the action of the cam ring 19, now operating in reverse, and a series of positive, direct, rapid rotational hammerheavy blows are imparted to the anvil jaws as the impact members move into and out of the spaces between the jaws. These blows soon break the nut or bolt loose and the motor is then free to rapidly unscrew the nut by reason of the clutched engagement between the hammer and the anvil.

As soon as the nut is free, the operator may control the spinning of the motor by opening and closing the throttle valve ZI. On closing the valve 2|, the live air pressure supplied to the tool at thesupply-hose presses the brake plunger H3 against the brake disc II I and stops the rotation of the hammer and the connected anvil. In this way the tool is under full and complete control and the operator can prevent a nut from flying olf a bolt when unscrewed. This feature is of particular value when removing large nuts overhead.

As heretofore stated the tool is relatively light in weight, for ease in handling and manipulation, yet suiliciently strong, rugged and powerful for heavy duty operations. The impact members 15 and the anvil jaws 59 are of relatively heavy solid section to electively drive the anvil element by the hammer element when the two are in clutch and to withstand the direct, positive heavy rotational hammer blows which the im' pact members impart to the anvil jaws when the anvil element is held against free rotation. With the impact members 15 in rectangular solid block form and slidablymounted for rectilinear movement in slots in the hammer element, relatively wide surfaces are provided on the opposite sides of the impact members to adequately'support them within the slots against the blow delivering impacts and to positively and directly engage the impact receiving surfaces of the jaws throughout the full extent thereof both axially and radially. 'I'his makes for positive and eertaln action at all times and the power factor of the tool is enhanced in tightening up nuts and bolts and in removing tight or rusted ones. It will be noted fiom Fig. 17 that the co-acting surfaces of the impact members and the anvil jaws are in parallelism when the parts are engaged.

The momentum acting cam ring 1S is important in that the releasing of the impact members I5 from the anvil jaws 59 is handled independently of the hammer and anvil elements. With this arrangement, a more direct and solid -blow can be struck by the impact members due to the fact that the releasing is handled by the floating or over-running cam independently of springs which would break or a slipping action which loses eiectiveness by wear as in tools as heretofore designed and constructed. Moreover, with an over-running cam ring the releasing action is positive and sure and the impact members are moved completely back in their slots to free the anvil jaws immediately following a blow delivering impact thereon.

The shifting means being responsive to the pressure iiuid supplied to the tool automatically sets the'stop bar 86 or equivalent means carried by the hammer by merely turning the reversing valve 26 for the selected direction of rotation for the hammer.

The brake feature is also important as above indicated and there is considerable advantage in having the impact members 'I5 held from rotation with the hammer by the side walls of the slots in which the impe-ct members are reciprocably mounted. It is to be understood that the brake device operates in either direction of rotation of the motor. The key between the cylinder bushing 2 and the cylinder case 3 will be Yseen at |39 in Figs. 9, 13 and 14. Other and furtherv advantages of my improved construction will be apparent to those skilled in the art to which the' invention appertains. in the manner required for effective operation and the cylinder bushing and rotor blades will be lubricated automatically from an oil reservoir contained within the handle section I5.

The details of construction and arrangement of parts shown and described may be variously changed and modified Without departing from the spirit and scope of my invention, except as pointed out in the annexed claims.

I claim as my invention: l. An impact clutch comprising a rotatable hammer, a rotatable anvil having spaced jaws,"

The tool Will be lubricated tracting means receiving rotation from the hammer and movable by momentum relatively thereto in its direction of rotation upon the termina.- tion of an impact to automatically move the impact members out of the orbital path of the jaws, and means for driving the hammer.

2. An impact clutch comprising a rotatable hammer, a rotatable anvil having spaced jaws, reciprocable impact members slidably carried by the hammer in slots therein and movable by centrifugal force into the orbital path of the jaws to deliver a succession of impacts to said jaws in the rotation of the hammer relatively to the anvil, revolvable retracting means rotatable independently of the hammer in its direction of rotati'on upon the termination of an impact to automatically slide the impact members back into the slots and out of the orbital path of the jaws, and means for driving the hammer.

3. An impact clutch comprising a rotatable hammer, a rotatable anvil having spaced jaws, reciprocable impact members slidably carried by the hammer in slots therein and movable by centrifugal force into the orbital path of the jaws to deliver a succession 'of impacts to said laws in the rotation of the hammer relatively to the anvil, revolvable retracting means rotatable independently of the hammer in its direction of rotation upon the termination of an impact to automatically slide the impact members back into the slots and out of the orbital path of the jaws, said slots holding the impact members against rotation with respect to the hammer, and means for driving the hammer.

4. An impact clutch comprising a rotatable hammer, a rotatable anvil having spaced jaws, reciprocable impact members slidably carried by the hammer in slots therein and movable by centrifugal force into the orbital path o1' the jaws to deliver a. succession of impacts to said jaws in the rotation of the hammer relatively to the anvil, revolvable retracting means receiving rotation from the hammer and rotatable by momentum with respect thereto upon the termination of an impact to automatically slide the impact members back into the slots and out of the orbital path of the jaws, and means for driving the hammer.

5. An impact clutch comprising a rotatable hammer, a rotatable anvil having spaced jaws. reciprocable impact members slidably carried by the hammer in slots therein and movable by centrifugal force into the orbital path of the jaws to deliver a succession of impacts to said jaws in the rotation of the hammer relatively to the anvil, revolvable retracting means receiving rotation from the hammer and rotatable by momentum relatively to the hammer upon the termination of an impact to automatically slide the impact members back into the slots and out of the orbital path of the jaws, said impact members having relatively wide side surfaces substantially co-extensive with the side surfaces of the slots and the jaws,'respectively, to engage the impact members with the slots and jaws throughout approximately the full height thereof, and means for driving the hammer.

6. An impact clutch comprising a rotatable r hammer, a rotatable anvil having spaced jaws,

reciprocable impact members slidably carried by the hammer in slots therein and movable by centrifugal force into the orbital path of the jaws to deliver a succession of impacts to said jaws in the rotation of the hammer relatively to the anvil, a momentum acting ring element about to deliver a succession ofimpacts to said jawsY in the rotation of the hammer relatively to the anvil, a momentum acting ring element about the hammer and receiving rotation therefrom, said ring having recesses and cam surfaces therebetween for cooperation with said impact members, said recesses serving to receive and position the impactmembers in the orbitalpath of the jaws and said cam surfaces serving in the rotation of th ring by momentum relatively to the hammer upon the termination of an impact to slide the impact members back into the slots and out of the path of the jaws, and means for driving the hammer. v

8. An impact clutch comprising a rotatable hammer, a rotatable anvil having spaced jaws, reciprocable impact members slidably carried by the hammer in slots therein and movable by centrifugal force into the orbital path of the jaws to deliver a succession of impacts to said jaws in the rotation of the hammer relatively to the anvil, a momentum acting ring element about the hammer and receiving rotation therefrom, .said

ring having recesses and cam surfaces thereber atively to the hammer when retracting the impact members and to position the recesses opposite the impact members when free of the jaws.

9. An impact clutch comprising a, rotatable hammer, a rotatable anvil having spaced jaws, reciprocable impact members slidably carried by the hammer in slots therein and movable by cend trifugal force into the orbital path of the jaws to deliver a series of impacts on said jaws in the rotation of the hammer relatively to the anvil, a momentum acting ring element about the hammer at Said impact members, said ring having recesses and cam surfaces therebetween for cooperation with the impact members, said recesses serving to receive and position the impact mem bers in the orbital path of the jaws and said cam surfaces serving in the rotation of the ring by momentum relatively to the hammer to slide the impact members into the slots and out of the path of the jaws upon the termination of an impact thereon, means for driving the hammer, spaced lugs on the ring, and a cross-bar carried by the hammer and engageable with said lugs for controlling the rotation of the ring in positioning the recesses and the cam surfaces with respect to the impact members.

10. An impact clutch comprising a rotatable hammer, a rotatable anvil having spaced jaws,

said hammer having a pair of upper and lower slots, reciprocable impact members slidably mounted in one of the slots and movable by centrifugal force into the orbital path of the jaws to deliver a series of impacts on said jaws in the rotation of the hammer relatively to theanvil, a momentum acting ring element about the hammer at the impact members, said ring having cam means to positively slide the impact members back into the slots and out of the orbital path of the jaws in the rotation of the ring by momentum relatively to the hammer upon the termination of an impact on the jaws, means for driving the hammer, spaced lugs on the ring, and a bar carried by the hammer in the other of the slots' and engageable with the lugs to control the rotation of the ring in positioning the recesses and the cam surfaces with respect to the impact members and the jaws.

11. An impact clutch comprising a rotatable hammer, a rotatable anvil having spaced jaws having impact receiving surfaces on the opposite sides thereof, impact members movably carried by the hammer and movable by centrifugal force into the orbital path of the jaws to deliver a series of impacts on said jaws in the rotation of the hammer relatively to the anvil, said impact members having striking surfaces on their opposite sides to strike the impact receiving surfaces of .the jaws in either direction of rotation of the hammer, a momentum acting ring element about the hammer and receiving rotation therefrom, said ring having cam elements acting on the impact members in the rotation of the ring by momentum relatively to the hammer to move the impact members out of the orbital path of the jaws upon the termination of an impact thereon,`

means for driving the hammer in either direction, and shiftable means for setting the ring for action onthe impact members in either direction of rotation of the hammer.

12. A portable power driven impact tool of the character described comprising in combination, a reversible pneumatic motor, a rotatable hammer driven by said motor, an anvil rotatably mounted with respect to the hammer and having spaced jaws having impact receiving surfaces on their opposite sides, impact members movably carried by the hammer and having striking surfaces on the opposite sides thereof, said impact members being movable by centrifugal force into the orbital path of the jaws to deliver a series of impacts on the jaws in either direction of rotation of the hammer relatively to the anvil, automatic retracting means acting independently of the hammer upon termination of an impact to move the impact members out of the orbital path of'the jaws, and means operable by the iluid pressure supplied to the motor for setting the retracting means for action on the impact members in either direction of rotation of the hammer.

13. In a portable power operated impact tool comprising in combination, a reversible pneumatic motor, a rotatable hammer driven by said motor, an anvil rotatablymounted in respect to the hammer and having spaced jaws having impact receiving surfaces on their opposite sides, impact members movably carried by the hammer and having striking surfaces on the opposite sides thereof, said impact members being movable by centrifugal force into .the orbital path of the jaws to deliver a series of impacts on said jaws in either direction of rotation of the hammer relatively to the anvil, revoluble retracting means receiving rotation from the hammer and rotatable by momentum relatively thereto upon termination of lan impact to automatically move the impact members out of the orbital path of the Jaws, and a shifter mechanism operable by the pressure fluid supplied to the motor for setting .the retracting means for action on the impact members in either direction of rotation ofthe hammer.

14. In a portable power operated impact tool of the character described comprising in combination, a reversible pneumatic motor, a rotatable hammer driven by said motor, an anvil rotatably mounted in respect to the hammer and having spaced jaws having impact receiving surfaces on their opposite sides, impact members movably carried by the hammer and having striking surfaces on the opposite sid'es thereof, said impact members being movable by centrifugal force into the orbital path of the jaws to deliver a series of impacts on said jaws in either direction of rotationof the hammer relatively to the anvil, a momentum acting ring element about the hammer and receiving rotation therefrom, said ring having means operable in the rotation of the ring by momentum in either direction relatively to the hammer to move the impact members out of the path of the jaws upon termination of an impact thereon, and a shifter mechanism operable by the pressure uid supplied to the motor for setting the ring for action on the impact members in either direction of rotation of the hammer.

15. In a portable power driven impact tool of the character described comprising in combination, a pneumatically operated motor, a hammer driven thereby, an anvil rotatably mounted with respect to the hammer and having spaced jaws, impact members movably carried by the hammer and movable by centrifugal force into the orbital path of the jaws to deliver a series of impacts on said jaws in the rotation of the hammer relative tothe anvil, means acting in response to the rotation of the hammer to move the impact members out of the orbital path ofthe jaws upon the termination of an impact thereon, a brake element engageable with the hammer, and piston means operable by the pressure fluid supplied to the motor for pressing the brake element against the hammer for stopping the rotation of the motor on turning oi the supply of pressure fluid thereto.

16. In a portable power driven impact tool of the character described comprising in combination, a pneumatically operated motor, a hammer driven thereby, an anvil rotatably mounted with respect to the hammer, an impact clutch for imparting a series of rotational hammer blows to the anvil in the rotation of the hammer relatively to the anvil, a braking element engageable with the hammer, piston means, a main passage for supplying pressure ud to the motor for rotating the same, a throttle valve in said passage, and supplemental supply passages connecting the piston means with the main supply passage on opposite sides of the throttle valve to operate the piston means in one direction to press the braking element against the hammer for holding the motor from rotation on closing the throttle valve and releasing the braking action on the hammer on opening the throttle valve.

17. An impact clutch comprising a reversible rotatable hammer, a rotatable anvil having spaced jaws having impact receiving surfaces on their opposite sides, impact members movably carried by the hammer and movable by centrifugal force into the orbital path of the jaws to deliver a series of rotational impacts on said jaws in the rotation of the hammer relative to the anvil, said impact members having striking surfaces on the opposite sides thereof to strike the impact receiving surfaces of the jaws in either direction of rotation of the hammer, a ring element about the hammer at said impact members, said ring element having means acting in the rotation of the ring element by momentum relative to the hammer upon the termination of an impact to automatically move the impact members out of the orbital path of the jaws to release the hammer from the anvil, spaced driving and stop lugs on the ring element, a drive bar carried by the hammer and engageable with the drive lugs to impart rotation to the ring element and with the stop lugs to limit the extent of rotation of the ring element following the withdrawal of the impact members from the anvil jaws, a shift ring for lifting the drive bar out of the path of the stop lugs to set the bar for driving against either side of the drive lugs, means for driving the hammer, and means for raising and lowering the drive bar.

18. In an impact tool of the character dev.scribed comprising in combination, a reversiblepneumatic motor, a hammer driven by said motor, a rotatable anvil having spaced jaws having impact receiving surfaces on their opposite sides, impact members movably carried by the hammer and movable by centrifugal force into the orbital path of the jaws to deliver a series of impacts on said jaws in the rotation of the hammer relative to the anvil, said impact members having striking surfaces on the opposite sides thereof to strike the impact receiving surfaces of the jaws in either direction of rotation of the hammer, a ring element about the hammer at said impact members, said ring element having means acting in the rotation of the ring element by momentum relative to the hammer upon the termination of an impact to automatically move the impact members out of the orbital path of the jaws to release the hammer from the anvil, spaced driving and stop lugs on the ring element1 a drive bar carried by the hammer and engageable with the drive lugs to impart rotation to the ring element and with the stop lugs to limit the extent of rotation of the ring element following the withdrawalof the impact members from the anvil jaws, a shift ring for lifting the drive bar out of the path of the stop lugs to set the bar for engaging either side of the drive lugs,and means responsive to the pressure uid supplied to the motor for raising and lowering the drive bar.

19. 'I'he combination as defined in claim 18 characterized by the fact that piston means operable by the pressure fluid supplied to the motor serve to raise and lower the drive bar.

20. The combination as defined in the claim 18 characterized by the fact that piston elements are in cylinders carried by the lower centerplate for the motor and operable by the pressure fluid supplied to the motor serve to raise the orbital path of the jaws to deliver a series of rotational blow impacts to said jaws in the rotation of the hammer relatively to the anvil, automatic retracting means acting in response to the rotationof the hammer for sliding the impact members back into the slots and out of the orbital path of the laws upon the termination of an impact, a centering element between the hammer and anvil and providing a limiting stop for the impact members, and means for driving the hammer.

22. An impact clutch comprising axially alined rotatable hammer and anvil elements, the latter having spaced jaws, reciprocable impact members slidably carried by the hammer in slots therein and movable by centrifugal force into the orbital path of the jaws to deliver a series of rotational blow impacts to said jaws in the rotation of the hammer relatively to the anvil, automatic retracting means acting in response to the rotation of the hammer for sliding the impact members back into the slots and out of the orbital path of the jaws upon the termination of an impact, a centering element between the hammer and anvil and providing a limiting stop for the impact members, said impact members having recesses at their inner ends to reing the hammer.

23. In a portable power driven impact tool of the character described comprising in combination, a pneumatically operated rotary motor, rotatably mounted hammer and anvil elements, the hammer element being connected to the motor for rotation thereby, centrifugally operable clutch means interposed between said elements for releasably connecting the same and for imparting a series of rotational hammer blows to the anvil in the rotation of the hammer by the motor relatively to the anvil, a brake disc about the hammer and engageable with a seat thereon, piston means for pressing the disc against said seat, means for supplying a motive fluid under pressure to the motor and to the piston means for operating the same, and valve means for controlling the supply of motive fluid to the motor and to the piston means, respectively, to release the brake disc from said seat on turning on the motivefluid to the motor and for pressing the disc against said seat to stop the rotation of the hammer and the motor on turning off the motive iluid thereto.

n 24. A revolvably acting impact clutch comprising a rotatable hammer, a rotatable anvil having spaced jaws, impact members movably carried by the hammer and movable by centrifugal force into the orbital path of the jaws to releasably connect the hammer to the anvil and to deliver a succession of rotational impacts to said jaws in the rotation of the hammer relatively to the anvil, revolvable retracting means for the impact members receiving rotation from the rotary motion imparted to the clutch and rotatable independently of the hammer about the axis thereof upon the termination of an impact to automatically move the impact members out of the orbital path of the jaws, and means for imparting rotary motion to the clutch.

25. A revolvably acting impact clutch comprising a, rotatable hammer, a rotatable anvil having spaced jaws, impact members movably carried by the hammer and movable by centrifugal force into the orbital path of the jaws to releasably connect the hammer to the anvil and to deliver a succession of rotational impacts to said jaws in the rotation of the hammer relatively to the anvil, a revolvable retracting element for the impact members rotatable relatively to the hammer about the axis thereof and receiving rotation fromrthe rotary motion imparted to the clutch, said element having cam means acting on the impact members in the rotation of the element independently of and in the direction of rotation of the hammer upon the termination of an impact to automatically move the impact members out of the orbital path of the jaws, and means for imparting rotary motion to the clutch.

26. In a portable power driven impact tool of the character described comprising in combination, a power operated rotary motor, an impact clutch vhaving a rotatable hammer connected to the motor for rotation thereby, an anvil rotatably mounted with respect to the hammer and having spaced jaws, impact members movably carried by the hammer and movable by centrifugal force into the orbital path of said jaws to releasably connect the hammer to the anvil and to deliver a series of rotational hammer blows to said jaws in the rotation of the hammer relatively to the anvil, and means for automatically retracting the impact members from the jaws upon the termination of an impact thereon, a brake mechanism for the motor, power means for applying and releasing said brake, means for conveying a motive uid to the motor and to the brake operating means, respectively, manually operable means for turning on and oi the power supply to the motor, and

means responsive to the power fluid supplied to the tool to control the operation of the brake operating means, said power iiuid responsive means acting to automatically release the brake on turning on of the power supply to the motor and applying the brake to stop the rotation of the motor on turning off of the power supply thereto.

FRITHIOF P. FORSS.

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