US2745528A - Reversible impact wrench - Google Patents

Description

May 15, 1956 Filed Jan. 5, 1953 L- A. AMTSBERG REVERSIBLE IMPACT WRENCH 3 Sheets-Sheet l INVENTOR a lssweA inmaszg ATTORNEY May 15, 1956 L. A, AMTSBERG 2,745,528

REVERSIBLE IMPACT WRENCH Filed Jan. 5, 1953 5 Sheets-Sheet 2 ATTO R N EY May 15, 1956 A. AMTSBERG 2,745,528

REVERSIBLE lMPACT WRENCH Filed Jan. 5, 1955 3 Sheets-Sheet 3 T1 1: .lEA

Fuu Z0140 INVENTOR [5575? AAnma-eg.

ATTO R N EY United States Pate'ntO REVERSIBLE IMPACT EVRENCH iLester A..Amtsberg, New Hartford, FN. Y.,"as signor to :Chicago Pneumatic Tool; Company,;New:York, N. Y.,

{a corporation. of New York Application January 5, 1953, SeriaiNo. 329,573

7.15 Claims. (Ci-f-192-r3il5) This invention relates to impactfclutches of the accumulator type in which the continuous rotation of a motor spindle is converted into a series of. rotational'impacts delivered by a hammer to an anvilgthe connection between the spindle and hammer comprising an accumulator which intermittently stores energy during the time when the hammer is stopped or is rotating slower than the spindle, and releasessuch energy to the hammer while .the latter is rotating faster than the spindle.

"The usual accumulator comprises a compression spring constantly pressing the hammer forwardly toward the anvil, and an arrangement of cam elements between the spindle and hammer, the cam elements being'disposed in ,a helical direction to convert the forward axial movement of the hammer into an additional forward driving movement, whereby the hammer alternatelyrotates.slower 'Ithanthe spindlewhile declutching, andfaster than the spindle during-its re-clutching movement. In order to "reducefriction the helical connection takesthej form of inclined: channels in'the spindle, forming an inner raceway, and cooperating with balls which also-roll in an outer ball raceway or groove in the hammer. For reversibility, the channels are made V shapeand the grooves 'in'the form of an inverted V, the sides or arms .of which merge; so that'oneare is eitectivewhen the wrench is driven clockwise and the other when the wrench isdriven ---counterclockwise. Such tools are employed for tightening'and loosening bolts, nuts, screws and'the' like,'.jbut

"also for other'uses where it is desired to obtain a rotary driving force in excessof that delivered by a continuously rotating spindle.

' -In a conventional impact wrenchas thus described, the

' angle of the helical cams, or of vthe arms of the V-shaped grooves, is-selected critically to bear a predetermined relationto the force of the spring, the speedof rotation of *the spindle and otherfactors, so that the hammer will complete its forward movement relative to the spindle at jprecisely-the same instant that thehammer jaw has com- '"pleted its movement of lost motion (usually"180),rela- *tive to the'anvil-andis-in position to deliver an impact to the succeeding-anvil 'jaw. Retarded forward movement would prevent thedevelopmentof the maximum hammer *'fspeed-,-and also Would-cause the-clutch jaws on teeth to i impact-under onlypartial engagement. Premature forward movement would attenuate the force of thejrota- "*tiveimpactby-permitting the hammer to deliver an impulse to the driving spindle, as there is"no;-'provision in the'prior-art -for permitting the hammer to continue-fror tating at fullspeed after it has reached the-extremebf its forward movement. In many instancesythe balls 'ride past the vertex of *theV-shaped races, causing the cam- :mingwzycle to reverse and the hammer to -start on its rrearward movement before the blow-is delivered. Such a a? reversal -is accompanied: by'reduction of speed-of the hammer as the latter releases some of its kinetioenergy -:.to're-.compress the spring. Thus the premature operation 2 of 'thetaccumulatorzresults :in' an attenuated blow; as well .as incomplete: engagement of the vclutchteeth.

'ice

*2 .An object of the present invention is to overcomethe disadvantages of conventional accumulator impact wrenches by permitting thehammer to continue rotating "at full speed, ;even 'after it has attainedits maximum forward position, if that event shouldoccur before the hamfiner-has advanced rotationally into re-engagement with the succeeding anvil jaw.

Another object is to --permit--the;hammerto; remain in its extreme forward position with-the ham'mer-jawsrotating in a'path which registers'with the anvil -jaws-dur ing a substantial partof the cycle of rotation ofthe clutch, thus insuring completeengagement of the jaws, andalso causing the-hammer to deliver blows in a rota-tional direction only. By-eliminating the axial component of-the blow --of the ha-mmer which occurs in conventional wrenches-when theha-mmer strikes while it is--st il1;-moving forward, the present invention tends}to reduce the -vibration transmitted to the wrench housing andtalso the shock to-"the operator.

A further'object of this invention is to prevent-any deleter-ious--effectsof improper timing ofthehamer when the-axial movement of the hammer on-the spindle is either premature or retarded in comparison with the 'rnove- ''ment of the hammer relative. to-the anvil.

Astill further object is to-permit use of-afstronger springand/ or; to-permit thearms of the helical cams or raceways to be constructed at-a -steeper;slope with a re sulting increase in theamount'of torqu'e capable --of delivery by the. clutch under: a continuous drive: and before any carnming occurs.

1 accompanying relative axial movement.

Another' feature of this invention. is a stacked arrangement of twosets of cams, one forright hand and-bne for left-hand rotation,-the ballsof-the -two sets-being spaced. axially, and valso at different distances irdmgthe axis of rotation, so that each arrn-of each raceway-can be -allotted sufiicient circumferential length-to accomplish the foregoing objects. Without confiictingwith 'the 'dimensi 'ons of: any other arm. because of. space limitations.

- Another object of theinvention isto provide animpact clutch which is rugged and.serviceable,reliable-in operation,-simple to manufacture and powerful foritssize and :weight.

- showing theimpact clutch and the clutch housing; the

- clutch being disengaged inresponse tofull load in-" the loosening direction;

Fig. 3 is a view similar to Fig.2 but with the cam sleeve 'in; elevation, the :clutch being disengaged in response to Fig. 4, is a longitudinal section of-ztheifront. part-of the ih mm l ig. 5- is;an; elevational view of the: front end ofgthe hammer;

Fig; 6 is an exploded view showinginperspective the anvil, hammer, cam sleeve and-'Jthe front part-of'the spindle;

.;-Fig.' 7 is a-zside elevation'ofthe cam sleeve; Fig. 8 is an elevational view of the rear: endofthecam sleeve;

Fig; 9 is an elevational viewofithe front endof-thecam sleeve;

Fig. is. a side elevation of the cam sleeve when turned 90 from the Fig. 7 position;

Fig. 11 is an enlarged longitudinal section of the cam sleeve looking in the same direction as Fig. 7;

Fig. 12 1s a cross-section through the spindle and hammer as indicated by arrows 12 in Fig. 1;

Fig. 13 is a cross-section through the spindle and anvil as indicated by the arrows 13 in Fig. 1;

Fig. 14 is a development showing the front end of the hammer and the two jaws on the anvil;

Fig. 15 is a diagrammatic view in development showing the path followed by a givenpoint on the hammer in its movements relative to the driving spindle; Fig. 16A is a development or diagrammatic view showing the relative positions of the spindle channels (dotted lines), cam sleeve (full lines) and hammer (broken lines), with the wrench under full load in a loosening direction of rotation, the spindle being displaced far to the right of the hammer, and the latter being lifted rearward relative to the spindle;

Fig. 16B is a development similar to Fig. 16A with the wrench driven in a loosening direction under no load or very light load, the spindle being displaced a short distance to the right of the hammer (as compared with its mean position) and the hammer being in forward position;

Fig. 160 is a development similar to Fig. 168, but with the wrench driving a very light load, or under no load, in the tightening direction, the spindle being displaced a short distance to the left of the hammer, and the latter still being in its forward position;

Fig. 16D is a development similar to Fig. 16C, with the wrench under full load in the tightening direction, the spindle being displaced far to the left of the hammer, the latter being lifted rearwardly of the spindle;

Figs. 2, 3 and 11 are drawn to a larger scale than that of Figs. 1, 4-10 inc., 12 and 13.

Referring to Fig. l, the clutch housing 21 is provided at its rear end with a flange 22 perforated to receive bolts 23 (one being shown). The bolts extend through the flange, and through a gear ring 24, transfer plate 25 and into the motor housing 26, thus securing these parts together. The transfer plate supports a bearing 27 in which is mounted a rotor shaft 28 adapted to be driven in either direction of rotation by any suitable means, for example a conventional pneumatic or electric motor (not shown). The transfer plate 25 also carries a thrust bearing 29 which supports the rear end of the spindle 30. In order to provide a driving connection between the rotor shaft 28 and the spindle 30, the latter is recessed to receive a plurality of idler gears 31 each supported for rotation on an associated pin 32 carried by the spindle. The idlers mesh with the toothed end of rotor shaft 28 and with the gear ring 24 to form a planetary type, reduction gear, transmission in a manner well understood in the art.

The front end of the spindle 36 has a reduced cylindri cal extension or pilot portion 33 which is fitted for rotation in a bore 34 formed in the rear end of a tool head 35. The tool head has a cylindrical exterior which is mounted for rotation in a bushing 36 secured within the front end of the clutch housing 21. The front end of the tool head is shaped to provide a detachable driving connection with any suitabl implement such as a wrench socket .(not shown). The rear end of the tool head is integrally formed with an anvil portion 37 having circumferentially spaced jaws 33, two being shown, although it will be understood that the principle of this invention is also applicable to anvils having only one jaw or having more than two jaws.

Referring to Fig. 6, the anvil jaws 33 are arranged to be driven by, and to receive rotational impacts from, a pair of cooperating jaws 39 projecting forwardly from a hammer 40. The hammer, which is constructed with considerable mass and therefore inertia, is arranged rearwardly of the anvil and in surrounding relation to. the

spindle 30 and is rotatable coaxially with the spindle. Supporting the rear end of the hammer is a guide 41 which is apertured at itsinside to form a journal for rotation about the spindle 353 and which is flanged at itsperiphery to provide a sliding fit with a counterbore 42 at the rear end of the hammer 49.

For guiding its front end, the hammer is provided with a bore 43 (Figure 2) which has a sliding and rotating fit on a sleeve 44 which is bored to fit the cylindrical periphery of the spindle. The sleeve 44, hereinafter'referred to as the cam sleeve, is an important feature of this invention and is arranged to move relative to the spindle 30 in both circumferential and helical directions. In a similar manner the hammer 48 is arranged to move relative to the cam sleeve in both circumferential and helical directions. The cam sleeve serves as an intermediate driving member between the spindle and hammer.

The driving connection between spindle 30 and cam sleeve 44 comprises a pair of channels 45 on the periphery of the spindle, said channels being of arcuate section to serve as an inner ball raceway; a pair of balls 46 mounted therein; and a pair of grooves 47 at the forward end and inside edge of the cam sleeve, the grooves also being of arcuate section to serve as an outer race for the same balls. Referring to Figs. 1, 6 and 16A, eachrchannel 4'5 has a circumferential arm 45C extending for 20, and a helical arm 45H forming a continuation thereof but inclined with a left hand lead and extending from the short arm. Similarly, each groove 47 has a circumferential arm 47C and a helical arm 47H extending 20 and 55 respectively, the helical arm being inclined at the same angle of elevation as the corresponding arms 45H of the channels.

The driving connection between the cam sleeve 44 and the hammer 4% comprises a pair of grooves 48 at the rearward and outer edge of the cam sleeve, each of said grooves being of arcuate section to serve as an inner ball race; a pair of balls 49 mounted therein; and a pair of channels 50 formed on the inner wall of the hammer 40. Referring to Figs. 3, 7 and 16A, each groove 48 has a circumferential arm 48C extending for 30 and a helical arm 48H forming a continuation thereof but inclined with a right-hand lead and extending from the short arm. Preferably, the helical groove 48H at the outer and rear edge of the cam sleeve has the same degree of slope or angle of elevation as the helical arm of the forward and inner groove 47H, excepting of course that they are oppositely directed. Each hammer channel 50 is of arcuate section to serve as an outer race for balls 49 and has a circumferential arm WC and a helical arm 50H extending for 30 and 75 respectively, the helical arm being inclined at the same angle of elevation as the corresponding arm 43H in the associated cam sleeve grooves.

The forward set of balls 46 are kept in place by a ball retainer 51 (Figs. 1, 2, 3 and 13), which is of generally cylindrical shape, in closely spaced surrounding relation to the cam sleeve 44. At its front end, the retainer has an integral disc portion 52 which is apertured to fit the pilot portion 33 of the spindle and which is seated between the rear face of the anvil 37 and a forwardly facing shoulder 53 on the spindle 30.

The hammer 40 is urged at all times toward the anvil 37, and is normally maintained in driving engagement therewith by means of a compression spring 54 surrounding the spindle 30. The front end of the spring seats against a washer 55 which abuts against the front end of the counterbored portion 42 in the hammer. The rear end of the spring is seated against the hammer guide 41 which in turn is supported by a thrust washer, 56 mounted on the spindle and resting against a shoulder 57 on said spindle.

new-52s .Withfihe' hammer-40 in its extreme forward-positionkin which the hammer jaws or teeth-.39cotnpltely'mesh with the teeth 38 on the driven anvil-"'37. The'pressure of spring .54 causes the hammer to'seat on the outer rear "-set of-balls 49 insuch a manner that'the latter-are maintained in the circumferential arms'SOC and 48C of the -ball races-in the hammer and cam s'leeve respectively.

The-spring pressure is transmitted through the cam-sleeve 44 thus causing the latter to seat on the i'n'nerfront-set of 'balls 46 in such a manner that the latter are maintained in the circumferential arms 47C and'45C of theball races in the cam sleeve 44 and spindle '30 respectively. The

position of the spindle with relation to 'the hammer would be as illustrated in Fig. 163 or in Fig. 16 C, or in some 1 intermediate position. The spindle'may'be turned relative to the hammer, between the limits illustrated in Figs. 16B

and 160 without imparting rotation or axial movement to the hammer. During this period of lost motion, the spindle may turn as much as 40 relative to the cam sleeve 44,

"representing the combined lengths'of circumferential arms 45C and 47C; and the cam sleeve may turn asmuch'as 60 -"relative to the hammer'40 representing the combined lengthof circumferential arms" 48C and'SOC; making a total lost motion of 100 between the spindle and hammer.

In'operation, let it be assumed that-the .parts are as shown in Fig. l with the rotative position of the spindle somewhere intermediate those shown in Figs. 16B and "16C and that the motor has started to supply torque to l the spindle 30 in a direction to tighten a'bolt or nut,

that is, in a clockwise directionlooking forward. The spindle turns relative to the cam sleeve 44, and the latter turns relative to the hammer 50 until the lost motion (amounting to 100 or less) is taken up, whereby the.

"until =-.the;hammer :islifted' completely; :out yofsdriving prezzlationxto the anvil: as shownin Fig. '3. iThe-relati'veiangular and axial positions of the hammer; ballsrcam sleeve and spindle are then approximatelysas. shown -.in.;-I6D.

It will be understood that ina'wrench-ofthistype, the driving @spindle rotates continuously while :rthe :hainmer rotates intermittently, beingbr'ought to a full stop,-:orrto an-qextremely low:speed, just-before declutching occurs.

In .?the 'present-iinventionyas well -.as in prior impact wrenches of thezaccumulator-type; the release o'frtheidriving connection between the 'hamrnerand anvil is immediately followed by an acceleration of the hammer,irstarting from rest: (or substantially -so) and continuing iuntilithe instantaneous angular-speed of the hammer far'exceeds that-of the continuously rotating-2' spindle. During the first part of the acceleration period, 'thespring'is further compressed, due to the factthat the spindle-is'ro'tating faster than the hammer, the force of the-rspring'being balanced by the axial component of the torque 'delivered through the ball raceways 50H ami- 48H,which torque is" being'employed to accelerate the hammer. "Themaxi- "mum lift of -the hammer away from the anvil occurs-at the instant that'the hammer speed catches up to that -of the -spindle, and thereafter the hammer reverses its movement relative to the spindle, with the hammer chan- -nels'--50H riding forward on the balls 49 andthe latter riding forward 'on the-cam grooves48H, the parts thusapproaching the postion shown in Fig/16C.

parts attain the position shown in' Fig. 16C. Thereupon,

and assuming that there is no appreciable resistance to the rotation of the tool head 35, the parts of the clutch, including the spindle 30, the two sets of balls,- the hammer and the anvil, all rotate in unison, the direction-being indicated by the arrow'in Fig. 16C. Now assuming that the tool head encounters a substantial and increased resistance to rotation, due to the frictional engagement between the threads of the driven nut and the associated bolt; the torque reaction is transmitted through the clutch .to. thespindle, causing the delivered torque to rise correspondingly. At this stage of operation, the parts are still substantially as shown in Fig. 16C and the rear balls 49 are driven by the inclined races 48H which in turn drive the hammer 40 along the inclined.

races or channels 50H. The driving force being trans- ,mitted through the balls 49 is thus resolved into two components, one in a rotational or tangential direction and the other being directed axially to tend to declutch the hammer or move it rearward. Now, the spring 54 is under pre-compresson with a force of say pounds, and as long as the axial component of torque reaction i-is-less than the spring force, the parts continue rotating inunisonin the relative position shownin Fig. 16C

- and the clutch teeth 38 and 39 remain fully meshed.

'When the tool head meets a predetermined high resistance, for example when the driven nut, bolt or screw becomes seated, the risein torque reaction is accompanied 1 by a corresponding rise in declutching component sufiicient to' balance, and then overcome, the following force of the spring. At this point, the spindle 30, along-with the cam sleeve 44, moves from the postion shown in Figs. 1 and 16C toward the postion shown in Figs.,3 and 16D, thereby causing the helical grooves 48H to ride overthe -balls49, and the latter to'ride over the helical-channels 50H .as-the balls lift'the hammer rearwardly in opposition .to the force of-the spring. As the spring is further compressed, it increasesiits holding force, but -this is quickly overcome by the rapidly risingtorquereaction along with a corresponding increase in the .declutching'component' forcescont'rolling the position of the hammer.

' immediately prior to the time that theparts are restored to-the Fig. 16C position, the hammer is'rotating'- much 'fa'ster'than the spindle and at-its maximum speed/"If --the hammer'jaws 39 at this time should happento becor'ne realighedin driving relation with the anvil jaws 38," they would deliver a rotational impact' to the anvil with "the maximum force permitted by the clutch. *dn 'thisrespect, the actionwould not'bemuch difii'erent from that o'f a conventional clutch that happens to deliver a perfectly timed blow. 'The present'intiention, however, permits the maximum blow to be delivered without requiring" perfect timing or a perfect balance between the various In-accordance with this invention, the hammer isp'ermitt'ed to continue rotating at substantially'its maximum specdeven after it has attained its ext'reme forward position asshown in Figs. land 16C. -Should that event occur"-hefore the hammer jaws reach the anvil jaws, the hammencon'tinues to rotate ahead of the driving spindle" 30 for a maximum lost motion period of 100, providing ample tolerance so that-the hammeris certain to deliver-a rotative impact to the anvil d'ur'ingthis period.

In practice, the speed of the spindle is so correlated with respect to the-force of 'the spring, angle 'of the grooves; and the hammer characteristics, that' the'impact- --ing jaWS on the hammer ordinarily strike the anvil jaws after the balls 49 have started to roll along the circumferential raceways 48C and'StlC, and long before-the other pair of balls has run to the end of the circumfer- =ential 'raceways 45C and 47C. In thisway, imperfect Throughout .the time that'thewrench operates inza'tighta oning-direction, the cam sleeve 4 4 does not;move;appre ciably, if mall, with respect to the spindle 3.0. ;;Duri-ng -suchoperation,.thehelical raceways 45H ,and 47H-hetween the .spindle and cam;.sleeve .do not functiom'and the same is true of the circumferential raceways 45C and 47C unless they are brought into action'when the impacts against the anvil are unusually retarded with relation to the axial movement of the hammer.

vAssume now, that the wrench is driven in a direction to loosen the nut, which direction is indicated by arrows in Figs. 2 and 1613. Upon application of the tool head 35 to the driven bolt, and upon starting the rotation of the spindle 30, the clutch parts are quickly moved to the Fig. 16B position after having been in an original position intermediate to the one therein shown and the one shown in Fig. 160. Since it is assumed that the driven bolt offers maximum resistance from the start, the clutch will not remain long in the Fig. 16B position, but the helical raceways 45H on the spindle will ride along the forward balls 46 and cause the latter to ride along the helical raceways 47H in the cam sleeve. The parts then move to the position shown in Figs. 2 and 16A whereupon the cam sleeve 44 and the hammer 40 are forced rearwardly against the pressure of spring 54 to disengage the clutch. The disengagement is followed by acceleration of the hammer and re-engagemcnt in a manner similar to the successive release and re-engagement during the tightening operation as previously described. It is, therefore, not necessary to describe the loosening operation in detail as it will be understood that the helical raceways 451-1 and 47H perform the same declutching and accelerating function in the loosening direction of rotation that the helical raceways 4821 and 501-1 perform during the operation in the tightening direction. It should be noted that the cam sleeve 44 forms in eifect a part of the spindle when the wrench is used for tight- 1 ening, and a part of the hammer when the wrench is rotated in the opposite direction for loosening.

Referring now to Fi 15, the broken line A-BC-D represents the path of a given point on the hammer in hammer accompanied by rotational displacement (relai tive to the spindle) when the wrench is used for a loosening operation and represents in development the path taken by a point on the hammer as the clutch parts v move from the Fig. 16B to the Fig. 16A position. v a like manner the section CD represents the displacement of the hammer in moving from the Fig. 16C to the Fig. 16D position. If the clutch were designed to permit the balls to run to the extreme end of their helical raceways, the inclined line B-A in Fig. would be extended beyond the point A to the point AA, and the line C-D would be extended beyond the point D to the point DD. It should be noted that the points AA and DD are 360 apart or twice the distance between one hammer jaw and the next, or between any one raceway and the corresponding point on the other raceway in the same path. This wide spread is permitted by stacking the raceways in different axial positions, and along different diameters. In prior art clutches of this type there was scarcely sufficient space for the line sections corresponding to AAB and CDD, because there was only one set of balls, both located in the same axial position and at the same distance from the center. In the present invention the stacked arrangement of the two sets of ball cams makes it possible to provide the dwell of 100 represented by the line B-C in Fig. 15. Because of this generous dwell the present device can tolerate a large degree of premature forward re-clutching movement of the hammer in response to spring pressure. Therefore it is now possible to employ a relatively heavy spring without damaging etfects. The advantage of the heavier spring is that it increases the constant or non- As an opposite direction of rotation.

alternative to the use of a relatively heavy spring,'the

angle of inclination of the ball raceways could be increased, thus forming a steeper cam and a lower component of declutching force for a given torque. The advantages of insured full engagement and higher run-up torque may be attained by a combination of a stronger spring and steeper cam both of which tend to cause premature (but permissive) axial re-clutching movement of the hammer.

The dimensions of the raceways 45, 47, 48 and 50, as mentioned in the foregoing description of an illustrative embodiment are not critical but may be varied widely as a matter of convenience in design. Thus in a commercial form of the present device the various arms of the ball raceways are dimensioned as follows: H, 96"; 45C, 18"; 47H, 64; 47C, 12; 48H, 91; 48C, 17; 50H, 69; 56C, 13. All four helical races in that structure are inclined with a lead of .984 inch.

What is claimed is:

1. An impact clutch comprising an anvil, a hammer for driving the anvil with a series of rotational impacts and arranged rearwardly of the anvil, a driving spindle, the anvil, hammer and spindle being coaxially rotatable in unison under some conditions of operation, but capahie of rotating at dilferent speeds, a spring arranged to exert forward pressure on the hammer tending to move the latter into driving engagement with the anvil, and a driving connection between the spindle and hammer, said connection having a helically arranged portion to cause the hammer to rotate faster than the spindle as his moved forwardly, thereon, said driving connection also having a circumferentially arranged portion to permit the hammer to rotate faster than the spindle after it has completed its forward axial movement.

2. An impact tool comprising a rotatable anvil, a rotatable hammer for driving the anvil with a succession of impacts, said hammer being arranged rearwardly of the anvil, a rotatable driving spindle, yieldable means urging the hammer forwardly relative to the spindle and anvil, and a driving. connection between the spindle and hammer, said driving connection including an intermediate sleeve, cooperating ball raceways carried by the intermediate sleeve, hammer and spindle respectively, each raceway having a helical arm communicating at one end with a circumferential arm, and a ball mounted in the cooperating raceways and movable in the circumferential and helical arms thereof, thereby connecting the hammer to the spindle for swivel movement in the extreme forward position of the hammer, but for relative helical movement when displaced from. the forward position 3. A rotary impact tool accorchng to claim 2, wherein the intermediate sleeve is carried by the spindle in one direction of rotation thereof, one of the racewaysconsisting of a channel formed in the hammer, and the other of said raceways consisting of a groove formed in the sleeve.

4. A rotary impact tool according to claim 2, wherein the intermediate sleeve is carried with the hammer in one direction of rotation thereof, one of the raceways consisting of a channel carried by the spindle, and the other of said raceways consisting of a groove formed in said sleeve.

' 5. A torque responsive clutch device comprising a driven element, a driving element rearwardly thereof, said elements having releasable inter-engaged teeth, a spring urging the driving element forwardly into engaged position, but yieldable in response to load, a continuously rotatable driving spindle coaxial with both clutch elements, a sleeve interposed between the spindle and driving element, said sleeve having a helical driving connection with the spindle, and also having a helical driving connection with the clutch driving element, said sleeve being carried by the spindle in one direction of rotation and being carried with the clutch driven element in the 6. A reversible rotary impact tool comprising a driving spindle, an intermediate driving member, a rotatable hammer, a spring urging the hammer axially relative to the spindle, cam means between the spindle and the intermediate member, and other cam means between the intermediate member and hammer, both cam means arranged for converting axial movement of the hammer relative to the spindle into relative rotary movement of the hammer relative to the spindle.

7. A reversible rotary impact tool according to claim 6, in which one of said cam means forms a left hand helix, and the other of said cam means forms a right hand helix, said intermediate member being carried by the spindle when the tool is impacting in one direction of rotation and being carried with the hammer when the tool is impacting in the other direction.

8. A reversible rotary impact tool according to claim 6, in which the cam means connecting the spindle to the intermediate member is axially spaced with relation to the cam means which connects the intermediate member to the hammer.

9. A reversible rotary impact tool according to claim 6, in which the cam means connecting the spindle to the intermediate member has a different diameter than the cam means connecting the intermediate member to the hammer.

10. A reversible rotary impact tool according to claim 6, in which the cam means connecting the spindle to the intermediate member is spaced both axially and radially with reference to the cam means which connects the intermediate member with the hammer.

11. A reversible rotary impact tool according to claim 6, in which the intermediate member comprises a sleeve arranged in surrounding relation to the spindle, said sleeve being surrounded by the hammer, said sleeve being generally of cylindrical shape, and having helical grooves at its front and rear ends forming part of the cam means aforesaid.

12. A reversible rotary impact tool according to claim 6, in which one of said cam means comprises a ball mounted in cooperating helical raceways formed in the spindle and intermediate member.

13. A reversible rotary impact tool comprising a driving spindle, a rotatable impact hammer mounted on said spindle for relative helical movement, a spring interposed between the spindle and hammer for urging latter axially, cam means connecting the spindle to the hammer and cooperating with the spring to convert relative forward movement of the hammer into relative clockwise movement, separate cam means interposed between the spindle and hammer and cooperating with the spring to convert relative forward movement of the hammer into relative counterclockwise movement, said cam means comprising a segment of a right hand helix, and a segment of a left hand helix, the two oppositely directed segments being spaced at different positions along the axis of the spindle in order to enable them to have greater length without interference with each other.

14. A reversible impact tool according to claim 13, in which the helical segments are of arcuate cross-section to form ball raceways.

15. A reversible impact tool according to claim 14, in which each raceway is formed in two connecting arms, one arm consisting of the helical raceway aforesaid, and the other arm extending circumferentially.

References Cited in the file of this patent UNITED STATES PATENTS 1,855,456 Miller Apr. 26, 1932 2,160,150 Jimerson et al. May 30, 1939 2,518,049 Mosier Aug. 8, 1950 2,539,678 Thomas Jan. 30, 1951

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