US2711661A - Power operated rotary impact wrench - Google Patents

Description

June 28, 1955 -E. H. SHAFF POWER OPERATED ROTARY IMPACT WRENCH Filed Oct. 29. 1955 2 Sheets-Sheet l f INVl2/TOR. IW'esf/Z 6 d .5- By- 7 ,4 TZQRNEY- b June 28, 1955 E. H. SHAFF POWER OPERATED ROTARY IMPACT WRENCH 2 Sheets-Sheet 2 Filed Oct. 29 1953 INVENTOR.

'57 .57 g ines/H Jfia/f I I 50 WW4 United States Patent rowan ornnaran noranv armor WRENCH Ernest H. Shafi, Lake Worth, Fla. Application Gctober 29, 1953, Serial No. 389,085

24 (Claims. or. s1 52.s

This invention, relates to improvements in a power operated rotary impact wrench. The principal objects of this invention are:

First, to provide an impact Wrench capable of applying high turning force to the work to which it is applied with relatively small power input to thewrench.

Second, to provide an impact wrench in which the coacti'ng' faces of the work driving element or anvil and the rotating impact member or hammer are engaged in straight abutting relation perpendicular to the path of movement of the hammer so thatthe full impact power of the hammer is applied on the anvil and so that the impacting'surfaces are not worn or distorted abrasion.

Third, to provide novel means for automatically dis,- engaging the impacting surfaces of a rotatable impact memberor hammerand a relatively stationary driven member or anvil without diminishing the force with which the hammer strikes the anvil. 7

Fourth, to provide novel magnetic means for returning a rotating impact member or hammer to anvil engaging positionafter the hammer has been disengaged from the anvil.

Fifth, to provide a novel and highly practical impact wreneh having a high torque rating.

Other objects and. advantages of the invention will be apparent from consideration of the following description and claims. The drawings, of which there are two sheets, illustrate three practical forms of the wrench. The preferred form of wrench is illustrated in Figs. 1 to 6 but the other forms of the wrench are also highly practical. ii

Fig, 1 is. a side elevational view of a wrench partially broken away in longitudinal cross section.

2 is a fragmentary transverse cross sectional view taken along the plane of the line 2-2 in Fig. 1 with the parts in the same relative position. i

Fig. 3. is a fragmentary longitudinal cross sectional view' similar to Fig. I but illustrates the parts in a different operative position. a I

Fig. 4- is a fragmentary transverse cross sectional view similar to Fig. 2 but illustrating the parts in the operative position shown in Fig. 3.

Fig. 5 is a fragmentary longitudinal cross sectional view takenalong the plane of the line 55 in Fig. 2.

Fig. 6 is a fragmentary longitudinal cross sectional view taken along the plane of the line 6 -6 in Fig. 4. v

Fig. 7 is a side elevational view partially broken away in cross section of a modified formof Wrench.

Fig. 8 is" an exploded view of elements of the wrench shown in Fig. 7 with portions of some elements broken away in longitudinal cross section. I

Fig. 9. is a plan view of the hammer retracting lever and drive member shown in Figs. 7 and 8. a M h Fig. 10 is a plan view of the, motor coupling drive member shown in Figs. 7' and 8. i i

Fig. 11 is a fragmentary transverse cross sectional view taken along the plane of the line 1111 in Fig. 7.

ant er lee Fig. 12 is a fragmentary cross sectional view taken along the plane of the line 12-42 in Fig. 7.

Fig. 13 is a fragmentary longitudinal cross sectional view through a further modified form of the wrench.

Fig. 14 is a fragmentary transverse cross sectional view taken along the plane of the line 14-14- in Fig. 13.

The first form of wrench illustrated in Figs. 1 to 6 includes a body having an upper casing 1 and a lower cylindrical housing 2 threadedly connected thereto. A handle grip 3 is connected to the casing and is provided with a trigger 4 for controlling the wrench. The casing 1 encloses a motor having a vertical shaft 5 projecting downwardly into the housing 2. Desirably the motor is of a reversible air operated type but the details of the motor are unimportant and so are not illustrated.

The lower end of the housing 2 is drawn into a neck 6 in which is journaled the spindle 7 of an anvil 8. An antifriction bearing for radially and axially supporting the anvil is indicated at 9. The lower projecting end of the spindle is squared or otherwise suitably shaped as at ill to receive socket wrenches or other tools. The spindle 7 is coaxial with the shaft 5 of the motor and is provided With a central recess 11 in its upper surface.

Positioned above the anvil 8 is a hammer carrier block 12 which is of solid cylindrical shape and provided with a depending pilot pin 13 received in the recess 11 to center the carrier with respect to the anvil.

T he upper end of the hammer carrier is provided with a centering stud 14 that projects upwardly into an annular drive member or sleeve 15. The stud 14 is relatively rotatable with respect to the drive member 15 but the upper end of the drive member 15 is non-rotatably and drivingly engaged with the lower end of the motor shaft 5 as by the formation of flats on the shaft and the drive member.

The upper end of the anvil 3 within the housing 2 is externally conical as at 16 and is provided with a downwardly and outwardly inclined lobe 17 the side edges 18 of which are arranged in axially and radially extending planes which intersect the axis of rotation of the anvil. The faces 18 on the lobe 17 are arranged to be struck by coacti'ng faces formed on the sides of a depending projection 19 formed on the underside of a tubular hammer member 29. The lower end of the hammer member 20 is internally or concavely conical to embrace the conical end 16 of the anvil and the striker faces on the sides of the projection 19 are arranged in radially and axially extending planes which intersect the axis of rotation of the hammer carrier 12. The tubular hammer 20 is rotatably drivingly connected to the hammer carrier 12 by a transverse pivot pin 21. The interior of the tubular hammer 20 is cut away or relieved as at 22 to permit the hammer to tilt transversely to the axis of rotation of the hammer carrier sufficiently to disengage the striker faces of the projection 19 from the faces 18 on the lobe of the anvil by straight axial motion of the coacting impact faces. Fig. 1 illustrates the elements at the point of impact between the striker face on the hammer and one face of the lobe of the anvil. Fig. 3 illustrates the elements just after the impact surfaces have been disengaged.

In order to rotate the hammer 2'0 the upper end thereof is provided with diametrically opposed axially extending slots or notches 23 arranged in the same general plane as the pivot pin 21. The notches 23 receive radially projecting lugs 24 formed on the lower end of the drive sleeve 15. The relative sizes of the notches 23 and lugs 24 is such that the lugs do not interfere with tilting motion of the hammer as is shown in Figs. 5 and 6.

The lugs 24 and the point of engagement thereof with the hammer it? is spaced vertically above the pivot pin 21. Thus as the drive member or sleeve 15 and hammer 2t rotate the impact faces of the hammer and anvil into coacting relation as shown in Fig. l, the continued turningforce applied by the drive member and its lugs 24 applies a tilting force to the hammer above the pivot 21 and the hammer is automatically disengaged from the anvil after applying an impact blow thereto. The striker faces of the hammer iii) are then free to rotate over the lobe 17 of the anvil as is shown in Fig. 3. Continued rotation of the downwardly tilted edge of the conical under surfaces of the hammer causes the lobe 17 to engage the conical undersurface of the hammer and cammingly return the hammer toward the upright position illustrated in Fig. 1.

In order to speed the returning motion of the hammer 29 to upright position and to partially resist the tilting of the hammer there is provided in the upper end of the hammer a permanent bar magnet which is set radially into the wall of the hammer on the opposite side thereof from the striker projection 19 and opposite the drive member 15. The drive sleeve or member 15 and magnet 25 are mutually magnetically attractive so that as the lobe 17 starts to return the hammer to upright position the pull of the magnet on the sleeve 15 rapidly returns the hammer to an upright position ready for the next impact of the hammer against the anvil. The continuing attraction of the magnet 25 to the sleeve 15 assures that the hammer will not be tilted away from the lobe 17 until the full impact force of the rapidly rotating hammer has been imparted to the anvil.

The wrench will operate equally well in either direction of rotation and will deliver a sharp impact blow between the striker faces of the hammer and the impact faces of the lobe on the anvil. The coacting faces extend in perpendicular relationship to the path of travel of the hammer at the time of impact so that all the energy stored in the hammer during its rotation is transmitted to the anvil.

The modified form of wrench illustrated in Figs. 7 to 12 is provided with the same type of case 1A, housing 2A, handle 3A, and trigger 4A as the first form of the wrench. The casing 1A encloses a similar type of motor having a shaft 5A projecting downwardly into the casing. The anvil 26 is journaled in the lower end of the housing and is provided with a downwardly projecting spindle 27. The upper face of the anvil 26 is centrally recessed as at 28 coaxially with the motor shaft and is generally flat except for a raised segmental lobe 29 having radially and vertically extending impact surfaces 30 on its edges.

A generally cylindrical hammer carrier 31 is provided with a depending pilot stud 32 received in the recess 23 and is provided with a coaxial recess 33 in its upper face relatively rotatably receiving a pilot portion 34 on the end of the motor shaft 5A. The upper face of the hammer carrier 31 is recessed as at 35 and the side of the hammer carrier defines a vertical groove 36 opening at its upper end to the recess 35. The groove 36 vertically slidably receives and radially retains the hammer 37 and the lower end of the hammer is provided with radially and axially extending striker surfaces 38 which are adapted to project downwardly below the hammer carrier and coact with the impact surfaces of the lobe on the anvil.

The upper end of the hammer 37 has an inwardly facing horizontal slot 39 formed therein which opens to the recess 35 on the top of the hammer carrier. A circular lever member 40 is positioned in the recess 35 and around the motor shaft 5A with a projecting edge or lip 41 extending into the slot 39. The undersurface of the lever 40 is angled as at 42 so that the lever may rock on the surface of the recess 35 to raise and lower the lip 41 and the hammer 37. Projecting from diametrically opposed sides of the lever 40 along the axis of rocking motion of the lever are lugs 43 which are drivingly engageably received in slots 44 provided therefor in the side walls of the recess 35 in the hammer carrier. A generally cylindrical drive member 4-5 projects through the lever 49 with sufllcient clearance so as not to interfere with the tilting of the lever 49. The drive member 45 is relatively non-rotatable and drivingly connected to the flat portion 46 of the shaft 5A. The upper end of the drive member 45 carries a semi-circular flange 47 having diametrically opposed drive faces 48 on its ends. The flange 47 and drive faces 48 engage and coact with the oppositely facing drive faces 49 formed on the top of the lever 40 by downwardly stepping or shouldering the top of the lever.

The drive faces 49 of the lever are positioned axially above the lugs 43 thereon so that drive forces applied to the faces 49 are displaced axially from the reaction forces applied to the lugs 43 by the hammer carrier. A tilting force is thus applied to the lever particularly when the hammer carried by the hammer carrier engages the lobe of the anvil and tends to stop rotation of the hammer carrier and the lugs 43. This tilting force raises the lip 41 of the lever and thereby raises the hammer 37 out of engagement with the lobe on the anvil so that the hammer and hammer carrier can continue their rotation.

In order to return the hammer 37 vertically downwardly in the slot 36, the upper face of the anvil 26 has a plurality of radially extending permanent horseshoe magnets 50 set therein between the impact faces of the lobe 29. The hammer 37 is made of magnetically attractive material and as the hammer is rotated over the magnets 50 by the hammer carrier the magnets draw the hammer downwardly for a succeeding blow on the lobe of the anvil. In order to increase the effectiveness of the magnets 50 in returning the hammer to striking position the upper face of the anvil 26 is cammed or raised upwardly as at 51 (see Fig. 8) on the opposite side of the anvil from the lobe 29. This reduces the spacing between the magnets and the rotating hammer to increase the pull of the magnets on the hammer. As in the first form of the wrench described the hammer, hammer carrier and drive mechanism will operate equally well in either direction of rotation. The impacting faces of the hammer and anvil are disposed perpendicular to the path of movement of the hammer at the point of impact for full utilization of the energy stored in the hammer and the hammer carrier.

Figs. 13 and 14 illustrate a modified manner of mounting the magnets which attract the hammer toward the anvil. Vertically extending bar magnets 52 are set into the bottom surfaces of the hammer 37B and the top surface of the anvil 26B is left flat between the sides of the lobe 29 thereon. The bar magnets 52 thus continually urge the hammer 37B downwardly toward the anvil. In order to reduce the downward attraction of the magnets and the downward pull on the hammer at the point of impact the top surface of the anvil 26B is drilled or otherwise cut away as at 53 on each side of r the lobe 29. This reduces the mass of metal opposed to the magnets at the point of impact and facilitates the disengaging lifting motion of the hammer by the lever 40. It should be understood that the hammer 37B and hammer carrier 31 shown in Figs. 13 and 14 are provided with the same type of driving and actuating structure as that shown in Figs. 7 to 12.

I have thus described three highly practical arrangements of my wrench mechanism. In each form of the wrenches described the magnetic attraction of a magnet is utilized to return the rotating hammer into striking position after the hammer has been disengaged from the anvil. The striking faces are disposed perpendicular to their path of motion and in each form of the Wrench the hammer is disengaged from the anvil by a tilting force created by axially offset application of driving and reaction forces in the driving connection to the hammer. This tilting or disengaging force is accentuated in all forms of the wrench by the impact of the hammer on the anvil so that while the hammers strike firmly and squarely against the anvil they are immediately and auto- 3 matically disengaged therefrom to permit substantially continuous rotation of thehammer. I have not attempted to describe all possible variations of the wrench structure as it is believed that such changes as may be desired may be made by others without further description and without departing from the spirit of the invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An impact wrench comprising, a housing having an air motor in the upper'end thereof, an anvil having a spindle journaled in the lower end of said housing coaxially with the shaft of the motor, a rotatable hammer carrier positioned between said shaft and said anvil and having portions maintaining axial alignment therewith, said carrier having an axially extending segmental slot formed therein, a magnetically attractive hammer ,slidable in said slot and having radially and axially extending striker faces on its lower end parallel with the axis of, rotation of said carrier, a lobe on the top of said anvil having axially and radially extending surfaces parallel to the axis of rotation of said carrier and cooperative with said striker surfaces in the lowered position of said hammer, the top of said carrier having a recess formed therein opening to the side of said hammer, the top of said hammer having a horizontal slot formed therein opening to said recess, a round lever embracing the shaft of said motor and rockably positioned in said recess with an edge portion engaged in the slot in said hammer, lugs on the opposite sides of the hammer engaging portion of said lever and rotatively driv- .2"

ingly engaged with said carrier, axially extending surfaces on the top of said lever and facing the hammer engaging portion thereof from each side of said motor shaft and axially spaced from said lugs, a drive member nonrotatably connected to said motor shaft and having diametrically spaced axially and radially extending drive surfaces cooperative with said surfaces on the top of said lever, and radially extending magnets mounted in the top of said anvil on the opposite side thereof from said lobe, the top of said anvil between the ends of the lobe being cammed upwardly and downwardly.

2. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing coaxially with the shaft of the motor, a rotatable hammer carrier positioned between said shaft and said anvil and havingportions maintaining axial alignment therewith, said carrier having an axially extending segmental slot formed therein, a magnetically attractive hammer slidable in said slot and having radially and axially extending striker faces on its lower end parallel with the axis of rotation of said carrier, a lobe on the top of said anvil having axially and radially extending surfaces parallel to the axis of rotation of said carrier and cooperative with said striker surfaces in the lowered position of said hammer, the top of said carrier having a recess formed therein opening to the side of said hammer, the top of said hammer having a horizontal slot formed therein opening to said recess, a round lever embracing the shaft of said motor and rockably positioned in said recess with an edge porin the top of said anvil on the opposite side thereoff'rom said' lobe.

3. An impact wrench comprising, a housing having an air. motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing, a

rotatable hammer carrier positioned between said shaft and said anvil, said carrier having an axially extending segmental slot formed therein, a magnetically attractive hammer slidable in said slot and having radially and axially extending striker faces on its lower end, a lobe on the top of said anvil having axially and radially extending surfaces cooperative with said striker surfaces in the lowered position of said hammer, the top of said carrier having a recess formed therein opening to the side of said hammer, a round lever embracing the shaft of said motor and rockably positioned in said recess with an edge portion vertically drivingly engaged with said hammer, lugs rotatively drivingly engaged between said lever and, hammer carrier and positioned on the opposite sides of the hammer engaging portion of said lever, axially extending surfaces on the top of said lever and facing the hammer engaging portion thereof from each side of said motor shaft and axially spaced from said lugs, a drive member on said motor shaft and, having diametrically spaced radially extending drive surfaces cooperative with said surfaces on the top of said lever, and radially extending magnets mounted in the top of said anvil on the opposite side thereof from said lobe.

4. An impact wrench comprising, a housing having an air motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing, a rotatable hammer carrier positioned between said shaft and said anvil, said carrier having an axially extending segmental slot formed therein, a magnetically attractive hammer slidable in said slot and having radially and axially extending striker faces on its lower end, a lobe on the top of said anvil having axially and radially extending surfaces cooperative with said striker surfaces in the lowered position of said hammer, a round lever embracing the shaft of said motor and rockably positioned with anedge portion vertically drivingly engaged with said hammer, lugs rotatively drivingly engaged between said lever and hammer carrier and positioned on the opposite sides of the hammer engaging portion of said lever, axially extending surfaces on the top of said lever and facing the hammer engaging portion thereof from each side of said motor shaft and axially spaced from said lug a drive member on said motor shaft and having diametrically spaced radially extending drive surfaces cooperative with said surfaces on the top of said lever, and a magnet mounted in the top of said anvil on the opposite side thereof from said lobe.

5. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spindle jonrnaled in the lower end of said housing, a rotatable hammer carrier positioned between said shaft and said anvil, said carrier having an axially extending slot formed therein, a hammer slidable in said slot and having radially and axially extending striker faces on its lower end parallel with the axis of rotation of said car rier, a l'obe on the top of said anvil having axially and radially extending surfaces parallel to the axis ofrotation of said carrier and cooperative with said striker surfaces in the lowered position of said hammer, a lever embracing the shaft of said motor and rockable axially with respect thereto, a rockably swingable edge portion of said hammer having a driving engagement with said hammer, means forming a rotary driving engagement between said hammer carrier and said lever, axially extending surfaces on said lever and facing the hammer engaging portion thereof from each side of said motor shaft and axially spaced from said means, a drive mem her on said motor shaft and having diametrically spaced drive surfaces cooperative with said surfaces on said lever, and a magnet mounted to attract said hammer toward said anvil on the opposite side thereof from said lobe. i

6. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spin- 76 die journaled in the lower end of said housing, a rotatable hammer carrier positioned between said shaft and said anvil, said carrier having an axially extending slot formed therein, a hammer slidable in said slot and having axially extending striker faces on its lower end, a lobe on the top of said anvil having axially extending surfaces parallel to the axis of rotation of said carrier and cooperative with said striker surfaces in the lowered position of said hammer, a lever embracing the shaft of said motor and rockable axially with respect thereto, a rockably swingable edge portion of said lever having a driving engagement with said hammer, means forming a rotary driving engagement between said hammer and said lever, axially extending surfaces on said lever and facing the hammer engaging portion thereof from each side of said motor shaft and axially spaced from said means, a drive member on said motor shaft and having diametrically spaced drive surfaces cooperative with said surfaces on said lever, and a magnet mounted to attract said hammer toward said anvil on the opposite side thereof from said lobe.

7. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing coaxially with the shaft of the motor, a rotatable hammer carrier positioned between said shaft and said anvil and having portions maintaining axial alignment therewith, said carrier having an axially extending slot formed therein, a hammer slidable in said slot and having radially and axially extending striker faces on its lower end parallel with the axis of rotation of said carrier, a lobe on the top of said anvil having axially and radially extending surfaces parallel to the axis of rotation of said carrier and cooperative with said striker surfaces in the lowered position of said hammer, the top of said carrier having a recess formed therein opening to the side of said hammer, the top of said hammer having a horizontal slot formed therein opening to said recess, a round lever embracing the shaft of said motor and rockably positioned in said recess with an edge portion engaged in the slot in said hammer, means on the opposite sides of the hammer engaging portion of said lever and rotatively drivingly engaged with said carrier, axially extending surfaces on the top of said lever and facing the hammer engaging portion thereof from each side of said motor shaft and axially spaced from said means, a drive member nonrotatably connected to said motor shaft and having diametrically spaced axially and radially extending drive surfaces cooperative with said surfaces on the top of said lever and magnets mounted in the bottom of said hammer to attract said hammer downwardly to said anvil, the face of said anvil being cut away adjacent the sides of said lobe to reduce magnetic attraction at those points.

8. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing, a rotatable hammer carrier positioned between said shaft and said anvil, said carrier having an axially extending slot formed therein, a hammer slidable in said slot and having axially extending striker faces on its lower end, a lobe on the top of said anvil having axially extending surfaces cooperative with said striker surfaces in the lowered position of said hammer, a lever embracing the shaft of said motor and rockably positioned on said carrier with an edge portion engaged with said hammer, means on the opposite sides of the hammer engaging portion of said lever and rotatively drivingly engaging said lever with said carrier, axially extending surfaces on the top of said lever and facing the hammer engaging portion thereof from each side of said motor shaft and axially spaced from said means, a drive member on said motor shaft and having diametrically spaced axially extending drive surfaces cooperative with said surfaces on the top of said lever, and a magnet mounted in the bottom of said hammer to attract said hammer downwardly to said anvil.

9. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing, a rotatable hammer carrier positioned between said shaft and said anvil and having portions maintaining axial alignment therewith, said carrier having an axially extending slot formed therein, a hammer slidable in said slot and having radially and axially extending striker faces on its lower end parallel with the axis of rotation of said carrier, a lobe on the top of said anvil having axially and radially extending surfaces parallel to the axis of rotation of said carrier and cooperative with said striker surfaces in the lowered position of said hammer, the top of said carrier having a recess formed therein opening to the side of said hammer, the top of said hammer having a horizontal slot formed therein opening to said recess, a round lever embracing the shaft of said motor and rockably positioned in said recess with an edge portion engaged in the slot in said hammer, means on the opposite sides of the hammer engaging portion of said lever and rotatively drivingly engaged with said carrier, axiaily extending surfaces on the top of said lever and facing the hammer engaging portion thereof from each side of said motor shaft and axially spaced from said means, and a drive member on said motor shaft and having diametrically spaced axially and radially extending drive surfaces cooperative with said surfaces on the top of said lever.

10. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing, a rotatable hammer carrier positioned between said shaft and said anvil, said carrier having an axially extending slot formed therein, a hammer slidable in said slot and having radially and axially extending striker faces on its lower end, a lobe on the top of said anvil having axially and radially extending surfaces cooperative with said striker surfaces in the lowered position of said hammer, a lever embracing the shaft of said motor and rockably supported with an edge portion engaged with said hammer, means on the opposite sides of the hammer engaging portion of said lever and'rotatively drivingly engaged with said carrier, axially extending surfaces on the top of said lever and facing the hammer engaging portion thereof from each side of said motor shaft and axially spaced from said means, and a drive member on said motor shaft and having diametrically spaced axially and radially extending drive surfaces cooperative with said surfaces on the top of said lever.

11. An impact wrench comprising, a housing having a motor and an anvil mounted in spaced relation therein, a hammer member rotatably mounted in said housing and having striker surfaces cooperative with said anvil, a drive member rotatably drivingly connected between said hammer member and the shaft of said motor, one of said members being tiltable transversely of its axis of rotation to shift said striker surfaces axially out of engagement with said anvil, said tiltable member having torque force applying areas spaced transversely with respect to its tilting axis and parallel thereto whereby rotary torque force and reaction force applied to the tubular member create a tilting force in said member, and a magnet positioned to draw said hammer to anvil engaging position after the hammer has rotated past anvil engaging position.

12. An impact Wrench comprising, a housing having a motor and an anvil mounted in spaced relation therein, a hammer member rotatably mounted in said housing and having striker surfaces cooperative with said anvil, and a drive member rotatably drivingly connected between said hammer member and the shaft of said motor, one of said members being tiltable transversely of its axis of rotation to shift said striker surfaces axially out of engagement with said anvil, said tiltable member having torque force applying areas spaced transversely with respect to its tilting axis and parallel thereto whereby rotary torque force and reaction force applied to the tubular member create a tilting force in said one member.

13. In an impact wrench having a drive shaft and an anvil spaced axially from said shaft, means for driving said anvil from said shaft comprising a drive element rotatable with said shaft and having transversely projecting drive surfaces on diametrically opposed sides thereof, a tiltable member embracing said drive element and having transversely spaced driven faces coacting with said drive faces, impact means connected to said tiltable memher and movable axially of said shaft into and out of rotatable impacting relation to said anvil by tilting motion of said tilting member, a support for said tiltable member relatively non-rotatably and angularly drivingly connected thereto along a line spaced axially below and generally parallel to the line of said driving and driven surfaces to locate the tilting axis of said tiltable member in spaced relationship to the plane in which rotative force is applied thereto whereby rotative driving and reaction forces on said tiltable member create a tilting force thereon, and magnetic means opposing the tilting force created in said tilting member.

14. In an impact wrench having a drive shaft and an anvil spaced axially from said shaft, means for driving said anvil from said shaft comprising a drive element rotatable with said shaft and having transversely projecting drive surfaces on opposed sides thereof, a tiltable member embracing said drive element and having transversely spaced driven faces coacting with said drive faces, impact means connected to said tiltable member and movable axially of said shaft into and out of rotatable impacting relation to said anvil by tilting motion of said tilting member, and a support for sad tiltable member relatively non-rotatably and angularly drivingly connected thereto along a line spaced axially from and generally parallel to the line of said driving and driven surfaces to locate the tilting axis of said tiltable member in spaced relation ship to the plane in which rotatve force is applied thereto whereby rotative driving and reaction forces on said tiltable member create a tilting force thereon.

15. An impact wrench comprising, a: housing having an air motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing coaxially with the shaft of said motor, a tubular hammer in said housing having an internally conical lower surface with an inclined projection with radially and axially extending striker surfaces on the sides thereof opposed to the end of said anvil, the upper end of said anvil having an externally conical surface with an inclined lobe on one side, the sides of said lobe lying in planes, parallel to the axis of rotation of said anvil and being cooperative with said striker surfaces, a hammer carrier rotatively centered with said anvil and positioned within said hammer, a pivot rotatively drivingly connecting said carrier with said hammer and permitting tilting of said hammer about an axis transverse to the axis of rotation of said anvil, said pivot being located above said lobe and extending transversely with respect thereto, a drive member non-rotatably connected to said shaft and positioned within the upper end of said hammer and having diametrically spaced axially and radially extending drive surfaces drivingly engageable with the surface of notches formedin the interior of said hammer above said pivot, and magnets set radially in the top of said hammer on the opposite side thereof from said striker surfaces to attract the top of the hammer to said drive member and tilt said hammer and striker surfaces into coacting relation to the lobe on said anvil.

l6. An impact wrench comprising, a housing having an air motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing coaxially withthe'shaft of said motor, a tubular hammer in said housing having an internally conical lower surface with an inclined projection with radially and axially extending striker surfaces onthe sides thereof opposed to the endof said anvil the upper end of said anvil having anexternally conical surface with an inclined lobe onone side, the sides, of said lobe lying in planes parallel to the axis of rotation of said anvil and being cooperative with said striker surfaces, a hammer carrier rotatively centered with said anvil, a pivot rotatively drivingly connecting said carrier with said hammer and permitting tilting of said hammer about an axis transverse to the axis of rotation of saidanvil, saidpivot being located above said lobe and extending transversely with respect thereto, a drive member non-rotatably connected to said shaft and positioned within the upper end of said hammer and having diametrically spaced axially and radially extending drive surfaces drivingly engageable with surfaces formed in the interior of said hammer above said pivot, and magnetsiset in the top of said hammer on the opposite side thereof from said striker surfaces to attract the top of the hammer to said drive member and tilt said hammer and striker surfaces into coacting relation to the lobe on said anvil.

17. An impact wrench comprising, a housing having an air motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing coaxially with the shaft of said motor, a tubular hammer in saidhousing having an internally conical lower surface with an inclined projection. with radially and axially extending striker surfaces on the sides thereof opposed to the end of said anvil, the upper end of said anvil having an externally conical surface with an inclined lobe on one side, the sides of said lobe lying in planes parallel to the axis of rotation of said anvil and being cooperative with said striker surfaces, a hammer carrier rotatively centered with said anvil and positioned within said hammer, a pivot rotatively drivingly connecting said carrier with said hammer and permitting tilting of said hammer about an axis transverse to the axis of rotation of said anvil, said pivot being located above said projection and extendirrg transversely with respect thereto, a drive member nonrotatably connected to said shaft and positioned within the upper end of said hammer and having diametrically spaced radially extending drive surfaces drivingly engageable with the surface of notches formed in the interior of said hammer above said pivot, said drive surfaces extending parallel to said pivotand being spaced therefrom, and a magnet set radially in the top of said hammer on the opposite side thereof from said striker surfaces to attract the top of the hammer to said drive member and tilt said hammer and striker surfaces into coacting relation to the lobe on, said anvil.

18. An impact wrench comprising, a housing having an air motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing, a tubular hammer in said housing having an inclined projection with radially and axially extending striker surfaces on the sides thereof opposed to the end of said anvil, the upper end of said anvil having an inclined lobe on one side, the sides of said lobe lying in planes parallel to the axis of rotation of said anvil and being cooperative with said striker surfaces, a hammer carrier positioned within said hammer, a pivot rotatively drivingly connecting said carrier with said hammer and permitting tilting of said hammer about an axis transverse to the axis of rotation of said anvil, said pivot being located above said projection and extending transversely with respect thereto, a drive member non-rotatably connected to said shaft and positioned within the upper end of said hammer and having diametrically spaced radially extending drive surfaces drivingly engageable with the surface of notches formed in the interior of said hammer above said pivot, said drive surfaces extending, parallel to said pivot and being spaced therefrom, anda magnet set radially in the top of said hammer on the opposite side thereof from said striker surfaces to attract the top of the hammer to said drive member and tilt said hammer and striker surfaces into coacting relation to the lobe on said anvil.

19. An impact wrench comprising, a housing having an air motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing, a tubular hammer in said housing having an internally conical lower surface with a projection with radially and axially extending striker surfaces on the sides thereof opposed to the end of said anvil, the upper end of said anvil having an externally conical surface with a lobe on one side,'the sides of said lobe being cooperative with said striker surfaces, a hammer carrier positioned within said hammer, a pivot rotatively drivingly connecting said carried with said hammer and permitting tilting of said hammer about an axis transverse to the axis of rotation of said anvil, said pivot being located above said projection and extending transversely with respect thereto, a drive member on said shaft having a radially extending drive surface drivingly engageable with the surface of a notch formed in said hammer above said pivot, and a magnet set in the top of said hammer on the opposite side thereof from said striker surfaces to attract the top of the hammer to said shaft and tilt said hammer and striker surfaces into coacting relation to the lobe on said anvil.

20. An impact wrench comprising, a housing having an air motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing, a

ibular hammer in said housing having a projection with radially and axially extending striker surfaces on the sides thereof opposed to the end of said anvil, the upper end of said anvil having a lobe on one side, the sides of said lobe being cooperative with said striker surfaces, a hammer carrier positioned within said hammer, a pivot rotatively drivingly connecting said carrier with said hammer and permitting tilting of said hammer about an axis transverse to the axis of rotation of said anvil, said pivot being located above said projection and extending transversely with respect thereto, a drive member on said shaft having a radially extending drive surface drivingly engageable with the surface of a notch formed in said hammer above said pivot, and a magnet set in the top of said hammer on the opposite side thereof from said striker surfaces to attract the top of the hammer to said shaft and tilt said hammer and striker surfaces into coacting relation to the lobe on said anvil.

21. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing coaxially with the shaft of said motor, a tubular hammer in said housing having an internally conical lower surface with an inclined projection with radially and axially extending striker surfaces on the sides thereof opposed to the end of said anvil, the upper end of said anvil having an externally conical surface with an inclined lobe on one side, the sides of said lobe lying in planes parallel to the axis of rotation of said anvil and being cooperative with said striker surfaces, a hammer carrier rotatively centered with said anvil, a pivot rotatively drivingly connecting said carrier with said hammer and permitting tilting of said hammer about an axis transverse to the axis of rotation of said anvil, said pivot being located above said projection and extending transversely with respect thereto, and a drive member non-rotatably connected to said shaft and positioned within the upper end of said hammer and having diametrically spaced axially and radially extending drive surfaces drivingly engageable with surfaces formed in the interior of said hammer above said pivot, said drive surfaces being positioned on a line generally parallel to said pivot and being located thereabove, said lobe on said anvil being relatively and cammingly engageable with the conical interior surface of said hammer to return the hammer from tilted position to upright striker surface and lobe engaging position.

22. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing, a tubular hammer in said housing having an internally conical lower surface with an inclined projection with radially and axially extending striker surfaces on the sides thereof opposed to the end of said anvil, the upper end of said anvil having an externally conical surface with an inclined lobe on one side, the sides of said lobe being cooperative with said striker surfaces, a hammer carrier rotatively centered with said shaft, a pivot rotatively drivingly connecting said carrier with said hammer and permitting tilting of said hammer about an axis transverse to the axis of rotation of said shaft, said pivot being located above said projection and extending transversely with respect thereto, and a drive member on said shaft and positioned at the upper end of said hammer and having a radially extending drive surface drivingly engageable with surfaces formed on said hammer above said pivot, said drive surface extending generally parallel to said pivot and being located thereabove, said lobe being rotatively and cammingly engageable with the tilted under surface of said hammer to swing said hammer toward erect striker surface and lobe engaging position.

23. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing, a tubular hammet in said housing having a projection with radially and axially extending striker surfaces on the sides thereof opposed to the end of said anvil, the upper end of said anvil having a lobe on one side, the sides of said lobe being cooperative with said striker surface, a hammer carrier rotatively centered with said shaft, a pivot rotatively drivingly connecting said carrier with said hammer and permitting tilting of said hammer about an axis transverse to the axis of rotation of said shaft, said pivot being located above said projection and extending transversely with respect thereto, and a drive member on said shaft and positioned at the upper end of said hammer and having a radially extending drive surface drivingly engageable with surfaces formed on said hammer above said pivot, said drive surface extending generally parallel to said pivot and being located thereabove, said lobe being rotatively and cammingly engageable with the tilted under surface of said hammer to swing said hammer toward erect striker surface and lobe engaging position.

24. An impact wrench comprising, a housing having a motor in the upper end thereof, an anvil having a spindle journaled in the lower end of said housing generally aligned with the shaft of said motor, a tubular hammer in said housing having a projection with axially extending striker surfaces on the sides thereof opposed to the end of said anvil, the upper end of said anvil having a lobe on one side, the sides of said lobe lying in planes parallel to the axis of rotation of said anvil and being cooperative with said striker surfaces, means retaining said hammer between said motor and said anvil and permitting tilting of said hammer about an axis transverse to the axis of rotation of said anvil, and a drive member non-rotatably connected to said shaft and positioned adjacent to the upper end of said hammer and having diametrically spaced axially and radially extending drive surfaces drivingly engageable with surfaces formed on the upper end of said hammer, said drive surfaces being positioned on a line generally transverse to the line of said striker surfaces, said drive surfaces being slidably engaged with said hammer to permit tilting of the hammer.

References Cited in the file of this patent UNITED STATES PATENTS 2,219,883 Amtsberg Oct. 29, 1940 2,581,033 Larson et al. Jan. 1, 1952 2,684,738 Kaplan July 27, 1954

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