US2576851A - Impact wrench - Google Patents

Description

J. P. NEWMAN Nov. 27, 1951 IMPACT WRENCH 2 SHEETSh-SHEET l Filed July 19, 1948 NIIIIIIIH I wv E .M M NE n 1N p. M l W. JY B Nm., 27, 1%?1 J. P. NEWMAN A21,576,85

IMPACT WRENCH Filed July 19, 1948 2 SHEETS--SHEET 2 /WTUQNES/S Patented Nov. 27, V1951 UNITED srrgg am@ ofFFICE This invention relates to a new and improved form of impact Wrench.

A particular object ci the invention is to provide a power driven impact wrench having means :for adjustment of the magnitude oi the blows or impacts delivered by the wrench.

Another object is to provide improved vstructure for alternately connecting and disconnecting the driven member from the power driven drive shaft.

Another object isto provide an impact Wrench having working parts which' are capable of 'economical manufacture in quantity and which may be readily disassembled for inspection, repair or replacement.

Further and morev detailed objects and advantages will appear herelnafter.

In the drawings:

Figure 1 is a side elevation partly in section showing a preferred embodiment of 'my invention.

Figure 2 is a front'elevation thereof.

ligure 3 is an axial sectional view vpartly broken away of that portion of the device indicated by the circle' 3--3`in Figure 1.

Figure 4 is a sectional view of a modified form of the device illustrated in Figure 3.

Figure 5 is a sectional elevation taken' substantially on the lines 54-5-as shown' in FigureS.

Figure 6 is a sectional view taken substantially on the lines 5-'-6 as shown in Figure'fl.

Figure 7 is an end View oi the adjusting wedge used in connection withmy invention.

Figure 8 is a side elevation of the*v adjusting wedge.v

Figure 9 is a side elevation of the cam member utilized in connectionwith that form-oi my invention shown in Figures 1 and 3.

Figure 10 is a rear elevation'thereof.

Figure 11 is a front elevation of the cam member.

Figure 12 kis a side elevation partly brokenv away of the driver member employed in that form oi' my invention shown in Figures 1 and 3.

Figure 13 is a front end elevation thereof.

Referringto the drawings, the impact Wrenchv embodying my invention may be provided with an electric motor I0 suitably mounted within a housing ll. A downwardly extending handle portion l2 on the housing Il is proportioned to be received Within the palm of the hand of the user, and a trigger element I3 pivotally mounted on the handle portion is adapted to operate a control switch (not shown) for regulating the operation of the electric motor I0. Electrical current rfor the `vmotor `may bey supplied through 7 Claims. (Cl. lim-30.5)

extends into the bearing sleeve 28.

the cable M. Aswitch leverlllmay` also be mountedon `the handle l2 for reversing the di# rection or the motor Viii-when desirech It is Irecognized that an -air driven motcrniay-besub'- stituted for the velectric motor if desired.,` since the type of' powermeans employed for turning the drive shaft doesnot constitute an important part of my'invention;

Reduction gearingmay be provided fordriving the drive' shaft'lt from the motor shaft il, and as shown in the drawings this gear-ing may include the small pinion gear lon theA motor shaft driving the larger gearllon thel countershait 2Q. A pinion 2l also xed on the countershaft it engages the largerfdriven'gear 22 which is fixed to the drive-shaft lli by any convenient means suchy as, for-example, the'key 23. The housing H provides suitable bearingsA for the motor shaft li and lfor-the vrearward-end of the drive shaft I6.-

A cylindrical housing extensionV orfshellis telescopcally received.V over -the forwardl projec' tion 25 ofthe housing ll and is releasably con-` nected'thereto by means oi-the spring urged de# tent-.26 which is received inalateral opening 2l in the shell 2li. The'forward projecting end of the shell 2t is' connected byany suitable means to the bearing sleeve 28.- Afdrive shaft i'extends axially through the shell 2li andY its outer rend-23 A* resilient drive sleeve it encircles the driveshaft lt-for a portion of its length and is connected :at its rearwardy end in vdriving relationship with the drive shaft it by means offthefpin connection 3l. by pins 32 to the hammer member 33 which is` rotatably mounted within the shell 2te The sleeve member'llispreferably constructed ofrubber or oi rubberlike material so that the-forward end oiV the sleeve and the hammer member 33 may be'drivenby the `shaft l but be capable of relative angular movement with respect thereto.

shuttle or locking dog may move radially withil respect to the shaft 16.1` Acompres'si'on spring:

3l' mounted in a cavity 3B and restingon a shoul der 39 within thelocking dog 'urges -a contact shoe4t into engagement vvith'the sh'aft*l6so"' The forwardend ofthe sleeve Sil lis connected.`

The hammer member 33 is provided with 'a- This lockingdog` is-v that the locking dog 35 is normally biased to move in a radial direction. The locking dog 35 is pro vided on its forward side with a cylindrical bore 4I. The cylindrical portion 42 of the cam member 43 is positioned eccentrically with respect to the bore 44 which receives the forward end of the drive shaft I6. This eccentric 42 is received within the bore 4I in the locking dog 35.

The external cylindrical surface 45 of the cam member 43 is rotatably received within the cylindrical bore 45 of the driver member 41. The driver member 41 is in turn rotatably mounted within the bearing sleeve 28. As shown clearly in Figures 12 and 13 the driver member 41 is provided with circumferentially spaced projections 48 and 49 on which are provided driving jaw surfaces 50, 5I, 52 and 53. The forward end of the driver member 41 projects from the bearing sleeve 28 and is provided with a noncircular portion 54. This noncircular portion 54 ordinarily is formed as a square. A conventional socket member 55 is provided with a square opening 56 for reception of the noncircular projection 54 and is also provided with the usual socket 51 for reception of a nut or bolt head. A retaining spring 53 may be mounted in a groove on the forward end of the driver 41 for frictional engagement with the socket member to retain the same in position.

The projecting end of the driver 41 is axially threaded as shown at 59 to receive a .set screw 6I). A central protrusion 6I on the set screw 6U contacts the end 62 of the adjusting wedge member 63. As shown in Figures 7 and 8, this adjusting wedge has a nose portion 64 constituting a cylindrical element cut away by a plane 65 on its lower side and having laterally extending ears 65 at its forward end. The ears 66 are received within the slot 61 formed in the forward end of the cam member 43 (see Figures 9 and 10). The set screw 66 may be adjusted axially so that the adjusting wedge member 63 has greater or less clearance along the plane B5 with the complementary inclined plane surface 58 formed near the forward end of the drive shaft I6. The set screw 601 can be threaded axially to take up all clearance between the surfaces 65 and 68 or it can be retracted to permit clearance to develop between these plane surfaces. It will be noted that the adjusting screw is readily accessible through the threaded opening 59 for adjustment of the clearance between the surfaces 65 and 58 without disassembling the parts of the impact wrench.

In operation the drive shaft I6 is turned byY the motor II] and reduction gearing. S0 long as no resistance to rotation is imposed bythe socket member 55 the drive shaft I6, hammer member 33, locking dog 35, cam member 43 and driver 41 rotate as a unit with respect to the shell 24 and bearing sleeve 28. When resistance to rotation of the socket member 55 is encountered the driver 41 slows down relative to the drive shaft I6. The

shuttle or locking dog 35 moves radially outwardly under action of the spring 31. As soon as its end surface 69 moves angularly out of engagement with the arcuate surface 10 defining the inner boundary of the lug 49 on the driver 41, the locking dog 35 is then in the position shown in phantom lines in Figure 13. Since the driver 41 is rotating slower than the hammer member 33 and locking dog 35, the locking dog moves angularly relative to the driver 41 until it contacts the jaw face 50 on the lug 48. This results in an impact which is transmitted to the driver 41 and socket member 55. The hammer member 33 changes its rate of angular rotation very rapidly,

and its rotating inertia therefore is available to produce the required shock or impact.

When the shuttle or locking dog 35 engages the jaw face 50 it acts as a key to connect the hammer member 33 solidly with the driver 41. Since the hammer member is driven by the resilient sleeve 30 it is enabled to slow down or stop momentarily while the rotation of the drive shaft I6 continues, the relative rotation being absorbed by the resilience of the rubber-like sleeve 30. Continued rotation of the drive shaft I6 acts to turn the cam member 43 relative to the locking dog 35, and the eccentric 42 then engages the cylindrical surface 4I within the locking dog to retract it toward the axis of the drive shaft I6. As soon as the locking dog is retracted toward a central position it ceases to engage the jaw face 50 and takes its position with its outer end 69 in engagement with the arcuate surface 1I within the lug 48. Resistance to rotation imposed by the socket member 55 will continue to cause relative turning motion between the driver 41 and the drive shaft I6 with the result that the spring 31 will shift the locking dog 35 within its groove 34 in the hammer member 33 and cause it to strike a blow against the jaw face 53 on the lug 49. If the socket member 55 is engaged in tightening a nut on a bolt the effect is to apply two separate impacts per revolution of the drive shaft I6. When the nut reaches its final tightened position the socket member 55 and driver 41 cease to rotate at all with the result that the hammer member 33 comes to a stop and accelerates rapidly twice during each revolution of the drive shaft I6. If it is desired to remove a tightened nut from a bolt, or if it is desired to tighten a nut having left-hand threads, the direction of the motor I0 is reversed by means of the switch I5 and in such cases the jaw faces 52 and 5I on the driver 41 become operative. The action of the shuttle or locking dog 35 and cam member 43 is substantially the same, however.

The magnitude of the individual impacts transmitted to the driver 41 may be varied by adjusting the screw 60. This serves to adjust the amount of clearance provided between the surface 65 on the wedge member 63 and the surface 68 on the end of the drive shaft I5. In effect this produces a lost motion connection between the drive shaft I6 and the cam member 43. and this in turn changes the extent of relative angular movement permitted between the drive shaft I6 and the hammer member 33. The rubber-like sleeve 35 is therefore wound up to a greater angular extent when the wedge member 68 is retracted than when it is advanced. The rearward end of the rubber-like sleeve member 30 turns at a uniform angular rate with the drive shaft I6 since it is connected to it by drive pin 3l. The forward end, however, which is connected to the hammer member 33 turns nonuniformly and the extent of angular movement with respect to the shaft depends on the point in the operating cycle at which the cam 43 moves the locking dog 35 to release the driving connection between the hammer member 33 and the driver member 41. Thus, by turning the set screw to increase the clearance between the surfaces 65 and 58, a heavier impact is transmitted to the driver 41. Conversely adjustment of the screw 6D in a direction to reduce the amount of clearance between the surfaces 65 and 68 reduces the magnitude of the individual impacts. This is a highly desirable feature since it enables the imamai 5x pact wrench assembly to be used over ak wide range of sizes of bolts and nuts..

Should it be necessary or desirable to inspect the operating parts of the impact wrench assembly, the spring urged detent 26 is manually depressed to permit the shell 24 and associated parts contained therein to be moved axially away from the motor and gear housing I I.' The drive pin 3| remains in the drive shaft I0 and the sleeve 30 with its driving slots 30a for the pin 3| remains with the shell 24.

In the modied form of my invention shown in Figures 4 and 6, the radially movable shuttle 35 is replaced by an axially movable clutching dog |00. This clutching dog is mounted in a radial slot |0| formed in the end face of the hammer member 33a. The cam member 43 is replaced by the cam member |02 and the driver member 41a is provided with jaw faces |04. A coil spring encircles a portion of the drive shaft Mia. This spring engages the central boss portion |00 of the clutching dog |00 at one end and engages a collar |01 at the other end. The collar |01 is fixed on the shaft I 6a. The resilient sleeve 30a may be substantially identical to the sleeve 30 described in connection with the other figures. The shell 24a and bearing sleeve 28a. likewise may be identical to those previously described.

The cam member |02 is rotatably mounted within the driver member 41a and receives the adjusting wedge 03a in a manner similar to that previously described. The rearward end face |08 of the cam member |02 comprises a plane radial surface which is interrupted for a portion of its periphery by a raised eminence or cam nose |09. This raised eminence is symmetrical in that it slopes equally on both sides to a central high point. A counterbore I I0 is provided in the cam member |02 to receive the forward end of the boss |03 of the clutching dog when the dog is in its forward operative position. A rounded surface 1||| is provided on the clutching dog which is adapted to ride on the cam surface |09 and on the radial surface |08. Relative angular movement between the hammer member 33a and the cam member |02 causes the clutching dog |00 to move axially along the drive shaft I6a. The clutching dog |00 is moved to the left as shown in Figure 4 under action of the compression spring |05 and is moved to the right by the engagement of the cam surface |09 with the follower surface I. In operation the drive shaft I0a, sleeve 30a, hammer member 33a, cam member |02 and driver 41a rotate as a unit so long as no resistance to rotation is imposed upon the noncircular projection 54a. When such resistance is encountered the driver 41a slows down or stops. The clutching dog |00 is carried around with the hammer member 33a and the follower returns down the slope of the cam surface |09 and onto the radial surface |08. This brings the radially extending ear I I2 of the clutching dog |00 into engagement with one of the jaw faces |04. An impact results on the driver 41a. The hammer member 33a is then solidly connected with the driver ila through the sides of the slot |0I, clutching dog |00 and jaw face |04. The hammer member 33a remains at rest or rotates at a slower speed than the shaft Ia while the cam member |02 rotates to bring the raised eminence or nose |09 into contact with the follower portion |I I and thus move the clutching dog back into the bottom of the slot I0| and out of engagement with the jaw face |04. The end 'of the drive shaft' 16a is slanted' on an inclined plane surface 68a for engagement with the corresponding plane surface 65a on the adjusting wedge 63a. Movement of the adjusting screw 60a has the eff-ect of varying the magnitude of the individual impacts delivered to the driver 41 in the same lmanner as described above.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth, but my invention is of the full scope of the appended claims.

I claim:

i. In an impact wrench, the combination of a drive shaft; a driver member mounted co--l axially of the drive shaft; power means for rotating the drive shaft; a hammer lmember rotatably mounted coaxially of the drive shaft; a resilient driving member adapted to rotate the hammer member and driven from the drive shaft; a movabie ciu-tch element slidably lmounted with respect to the hammer member and constrained to rotate therewith; the drive member being provided-with a jaw face; a cam member; means including relatively adjustable elements forming an angular lost motion connection whereby the cam member may be driven from the drive shaft; resilient means acting to move the clutch element into engagement with the jaw face; and cooperating parts on the cam member and clutch element for moving the latter in a direction in opposition to said resilient means.

2; In an impact wrench, the combination of a drive shaft; a driver member mounted coaxially of the drive shaft; power` means for rotating the drive shaft; a hammer member rotatably mounted coaxially of the drive shaft; a rubberlike sleeve member adapted to rotate the hammer member and driven from the drive shaft; a mowy able clutch element slidably mounted with respect to the hammer member and constrained to rotate therewith; the driver `member being provided witha jaw face; a cam member; meansv including relatively adjustable elements forming an angular lost motion connection whereby the cam member may be driven from the drive shaft; resilient means acting to move the clutch element into engagement with the jaw face; and cooperating parts on the cam member and clutch element for moving the latter in a direction'in opposition to said resilient means.

3. In an impact wrench, the combination of: a drive shaft; a driver member mounted coaxially of the drive shaft and provided with a noncircular projecting end; a hammer member rotatably mounted coaxially of the drive shaft; a resilient driving member adapted to rotate the hammer member and driven from the drive shaft; a movable clutch element slidably mounted with respect to the hammer member and constrained to rotate therewith; the driver member being provided with a jaw face, a cam member; means including relatively adjustable elements forming an angular lost motion connection whereby the cam member may be driven from the drive shaft, one of said elements being accessible through the projecting end of the driver member; resilient means acting to move the clutch element into engagement with the jaw face; and means on the cam member for moving the clutch element in a direction in opposition to said resilient means.

4. In an impact wrench, the combination of z a drive shaft; a driver member mounted coaxially of the drive shaft and provided with a nonatraen circular projecting end; a hammer member rotatably mounted coaxially of the drive shaft and provided with a radial slot; a resilient driving member adapted to rotate the hammer member and driven from the drive shaft; a movable clutch element slidably mounted in the hammer member slot; the driver member being provided with a jaw face; a cam member; means including relatively adjustable elements forming an angular lost motion connection whereby the cam member may be driven from the drive shaft, one of said elements being accessible through the projecting end of the driver member; resilient means acting to move the clutch element into engagement With the jaw face; and means on the cam member for moving the clutch element in a direction in opposition to said resilient means.

5. In an impact Wrench, the combination of: a drive shaft having a plane surface inclined with respect to the shaft axis; a driver member mounted coaxially of the drive shaft and provided with a noncircular projecting end; a hammer member rotatably mounted coaxially of the drive shaft; a resilient driving member adapted to rotate the hammer member and driven from the drive shaft; a movable clutch element slidably mounted with respect to the hammer member and constrained to rotate therewith; the driver member being provided with a jaw face; a cam member; means including an adjustable wedge element adapted to cooperate with the said plane end surface on the shaft to form an angular lost motion connection whereby the cam member may be driven from the drive shaft; resilient means acting to move the clutch element into engagement with the jaw face; and means on the cam member for moving the clutch element in a direction in opposition to said resilient means.

6. In an impact wrench, the combination of a power driven shaft; a driver member and a hammer member each rotatably mounted coaxially of the shaft; a resilientdriving member encircling the shaft and adapted to rotate the hammer member upon rotation of the shaft; a radially movable clutch element slidably mounted with respect to the hammer member and constrained to rotate therewith; the driver member being provided with a jaw face; a cam member; means whereby the cam member may be driven from the drive shaft; resiilent means acting to move the clutch element radially into engagement with the jaw face; and cooperating parts on the cam member and clutch element for moving the latter away from the face in opposition to said resilient means.

7. In an impact wrench, the combination of: a drive shaft; a driver member mounted coaXially of the drive shaft; power means for rotating the drive shaft; a hammer member rotatably mounted coaxially of the drive shaft; a rubber-like sleeve adapted to rotate the hammer member and driven from the drive shaft; a radially movable clutch element slidably mounted with respect to the hammer member and constrained to rotate therewith; the driver member being provided with a jaw face; a cam member; means whereby the cam member may be driven from the drive shaft; a spring carried on the clutch member and acting against the drive shaft to move the clutch element radially outwardly into engagement with the jaw face; and an eccentric on the cam member for moving the clutch element radially inwardly in opposition to said spring.

JOHN P. NEWMAN.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,061,843 Meunier Nov, 24, 1936 2,158,303 Pott May 16, 1939

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