Abstract:
A self-tightening chuck mechanism is disclosed. The chuck mechanism has a jaw mechanism with a jaw elements which are slidably disposed within corresponding channels defined in a rotatable body. A threaded socket member, which is configured to be rotated in first or second directions relative to the jaw elements is rotatably disposed about and engaged with the jaw elements. An impact assembly is configured to interface with the threaded body to apply anti-rotational forces to the socket member to prevent rotation of the socket member to close the jaws when rotated in a first direction and open the jaws when rotated in a second direction. The thrust bearing is configured to apply a first set of forces to socket member when the socket member is relatively rotated in the first direction and a second set of forces when the socket member is rotated in a second direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/654,852, filed on Feb. 18, 2005 and U.S. Provisional 60/655,767 filed on Feb. 24, 2005. The disclosure of the above applications is incorporated herein by reference. 
     
    
     INTRODUCTION  
       [0002]     The present invention generally relates to a drill chuck for use with electric or pneumatic drill/drivers and more particularly to a drill chuck that employs an impacting ring to tighten or loosen the jaws of the drill chuck against the shank of a tool bit.  
         [0003]     Impact-type drill chucks, such as those which are described in U.S. Pat. Nos. 6,247,706 and 6,729,812, the disclosures of which are hereby incorporated by reference as if fully set forth in their entirety herein, employ an impacting ring that may be axially moved into a position where teeth on the impacting ring strike corresponding teeth that are formed on a socket that threadably engages the jaws of the drill chuck.  
         [0004]     With reference to  FIG. 1 , one such prior art drill chuck is generally indicated by reference numeral  1000 . The drill chuck  1000  includes a spindle  1020 , a plurality of jaw members  1022 , a threaded socket  1024 , a socket cover  1026 , an impact assembly  1028 , a cover shell or housing  1030 , and a sleeve  1032 .  
         [0005]     The spindle  1020  can have a forward section  1040 , a collar  1042  and a rearward section  1044 . The forward section  1040  can have a center through hole  1046  formed therein, while the collar  1042  can have a plurality of angularly disposed guide channels  1048  formed therethrough which intersect the center through hole  1046 . The rearward section  1044  can have a threaded hole  1050 , which is adapted to threadingly engage an output spindle of a power tool (not shown), and a snap ring groove  1051 .  
         [0006]     The jaw members  1022  can be slidably positioned in the guide channels  1048  and can each include a threaded surface  1052 , which is formed on an outer side, and a gripping surface  1054 , which is formed on a forward inner surface.  
         [0007]     The threaded socket  1024  can be disposed about the spindle  1020  and can have an internally tapered and threaded surface  1053  that is threadably coupled with the threaded surfaces  1052  of the jaw members  1022 . A plurality of recessed holes  1058  may be formed about the exterior of the threaded socket  1024 , while a plurality of socket teeth  1060  can be formed on the bottom surface of the threaded socket  1024 .  
         [0008]     The socket cover  1026  can be mounted about the forward section  1040  of the spindle  1020  and can contact the threaded socket  1024  on a side opposite the socket teeth  1060 . The impact assembly  1028  can include a spring  1070 , an impacting ring  1072  and a joint member  1074 .  
         [0009]     The impacting ring  1072  can include an annular body  1080 , one or more axially-extending guide members  1082  that can be coupled to the annular body  1080 , and a plurality of ring teeth  1092  that extend from a forward side of the annular body  1080 . The guide member  1082  can include a tooth-like projection  1086  having tapered sides  1088 . The ring teeth  1092  are configured so as to be capable of engaging the socket teeth  1060 , as will be described in detail, below.  
         [0010]     The spring  1070  can be disposed about the spindle  1020  and can abut joint member  1074  on the rearward side. The forward side of the spring  1070  can abut the rearward side of the body  1080  of the impacting ring  1072  and bias the impacting ring  1070  toward the threaded socket  1024 .  
         [0011]     A bearing ring  1100  and bearing washer  1102  can be disposed between the impacting ring  1072  and collar  1042  of the spindle  1020 . The cover housing  1030  can include a bottom cover shell  1110  and a top cover shell  1112 . The bottom cover shell  1110  can be generally container shaped, having a through opening for receiving the spindle  1020  and legs  1075  of the joint member  1074  therethrough. The bottom cover shell  1110  can include a plurality of grooves  1120  into which the guide members  1082  of the impacting ring  1072  can be received. Construction in this manner permits the impacting ring  1072  to move axially but not rotatably relative to the bottom cover shell  1110 , which is nonrotatably connected to the drill housing (not shown) via legs  1075  of joint member  1074 .  
         [0012]     The top cover shell  1112  can also be generally container shaped, having a through hole for receiving the spindle  1020  therethrough. The top cover shell  1112  can define a flange  1122 , which can abut the socket cover  1026  on a first side and the sleeve  1032  on an opposite side. The rear edge  1126 , of the top cover shell  1112  can define a plurality of shallow and deep locking recesses  1132  and  1134 , respectively, which are configured to receive the projections  1086  of the guide members  1082 .  
         [0013]     The sleeve  1032  can have a positioning member  1140  and a stop flange  1144 . The positioning member  1140  can have a cylindrical through-hole and a plurality of positioning ridges  1146  that extend radially inwardly so as to engage the forward section  1040  of the spindle  1020 . A bearing ring  1150  and bearing washer  1148  can be disposed between the stop flange  1144  and the flange  1122  on the top cover shell  1112 .  
         [0014]     When a drill bit  1160  is to be chucked in the drill chuck  1000 , the top cover shell  1112  of the housing  1030  is rotated to align the projections  1086  on a guide member  1082  with a plurality of deep locking recesses  1134  in the top cover shell  1112  so that the spring  1070  may urge the impacting ring  1072  forwardly so that the ring teeth  1092  engage the socket teeth  1060  to thereby resist relative rotation between the impacting ring  1072  and the threaded socket  1024 . Subsequent rotation of the spindle  1020  in a first rotational direction causes relative rotation between the spindle  1020  and the threaded socket  1024  that drives the jaw members  1022  toward the rotational axis of the spindle  1020  and tightens the jaw members  1022  against the shank  1162  of the drill bit  1160 . Continued rotation of the spindle  1020  and jaws  1022  will cause the socket  1024  to begin to rotate with the spindle  1020 , causing the socket teeth  1060  to ride over the ring teeth  1092  and urge the impacting ring  1072  in a rearward direction away from the threaded socket  1024 . Since the spring  1070  biases the impacting ring  1072  forwardly, the socket teeth  1060  will periodically strike the ring teeth  1092  as the threaded socket  1024  rotates. The impact of the socket teeth  1060  and the ring teeth  1092  will generate a torque that is applied to the threaded socket  1024  and that tends to further tighten the threaded socket  1024  against the jaw members  1022 .  
         [0015]     When the chuck  1000  is to be used in a drilling or driving operation, the top cover shell  1112  of the housing  1030  is rotated to align the projections  1086  on the guide members  1082  with the plurality of shallow locking recesses  1132  that are associated with the top cover shell  1112 . Thus aligned, impact ring  1072  is forced rearwardly so that the set of ring teeth  1092  are disengaged from the socket teeth  1060 . Accordingly, rotation of the socket  1024  is not inhibited by the teeth  1092  so that the socket  1024 , jaws  1022  and spindle  1020  will co-rotate.  
         [0016]     When the drill  1160  is to be removed from the chuck  1000 , the top cover shell  1112  of the housing  1030  is rotated to align the series of projections  1086  on a guide members  1082  with the plurality of deep locking recesses  1134  that are associated with the top cover shell  1112  so that the spring  1070  may urge the set of teeth  1092  that are formed on the impacting ring  1072  forwardly into alignment with socket teeth  1060  that are formed on the socket  1024  to thereby resist relative rotation between the impacting ring  1072  and the threaded socket  1024 . Subsequent rotation of the spindle  1020  in a second rotational direction opposite the first rotational direction causes the spindle  1020  and the socket  1024  to co-rotate such that the socket teeth  1060  periodically strike the ring teeth  1092 . Contact between the socket teeth  1060  and the ring teeth  1092  generates torque that is applied to the threaded socket  1024  in a manner that tends to loosen the socket  1024  from the jaws  1022  and then stop further rotation of the socket. As the spindle  1020  continues to rotate, relative rotation between the threaded socket  1024  and jaws  1022  will cause the jaws to loosen from the drill bit  1160 .  
         [0017]     While such drill chucks have been shown to adequately hold drill bits and tool bits, difficulties have been noted with the aforementioned arrangements when such drill bits and tool bits are to be removed from the drill chuck. Specifically, the “loosening torque” that is generated is dependent upon a number of diverse variables, including the rotational speed of the spindle and differences between static and dynamic coefficients of friction.  
         [0018]     In some situations, the variables that dictate the amount of torque that will be generated can change significantly between the time at which the drill is tightened in the chuck and the time at which the user desires to loosen the drill from the chuck. For example, the rotational speed of the spindle  1020  may be relatively lower when the drill is to be removed from the drill chuck  1000 , as for example where the transmission of the drill or drill/driver has been shifted into a lower speed ratio or in the case of a battery operated tool, the battery has discharged to a point where it a relatively lower voltage input to the motor of the drill or drill/driver. In such cases, the operator may need to change the speed ratio of the drill or drill/driver into a higher speed ratio and/or replace or recharge the battery to remove the drill, which can be rather inconvenient.  
         [0019]     The difference between static and dynamic coefficients of friction, however, tends to be somewhat more problematic. As is known, the dynamic coefficient of friction for a given material combination tends to be lower than the static coefficient of friction for that material combination. Since the amount of energy that is available to rotate the socket  1024  is related to the amount of energy that is dissipated between socket  1024  and the jaws  1022  in the form of friction, lower friction losses between the socket  1024  and the jaws  1022  will result in more applied power to the socket  1024 .  
         [0020]     Unfortunately, the coefficient of friction between the socket  1024  and the jaws  1022  is lowest when the socket  1024  is already moving relative to the jaws  1022  (i.e., when the socket  1024  is rotating and the jaws  1022  are being driven against the drill  1160 ) and highest when the socket  1024  is stationary relative to the jaws  1022  (i.e., when the jaws  1022  are against the drill  1160  and the operator is attempting to rotate the socket  1024  relative to the jaws  1022 ). Where the difference between static and dynamic coefficients of friction is significant, drill chucks of the type that are disclosed in U.S. Pat. Nos. 6,247,706 and 6,729,812 may not release the drill from the chuck without the operator&#39;s use of tools, such as wrenches and lock-out tools, that permit the operator to manually release the drill bit from the drill chuck. As those of ordinary skill in the art know, the manual release of a drill bit from a drill chuck is inconvenient.  
       SUMMARY OF THE INVENTION  
       [0021]     To overcome the deficiencies of the prior art, a number of embodiments are disclosed wherein the length of the impact assembly spring can be varied automatically (for example as between tightening and loosening) or manually (for example as selected by the operator). By shortening or lengthening the impact assembly spring, which means to increase or decrease the compression of the spring, the force exerted by the spring upon the impact ring and hence the torque exerted upon the jaws by the threaded socket can be varied. For example, in a first embodiment a chuck mechanism is disclosed having a user tightenable jaw mechanism. This mechanism has a plurality of engageable jaws, which are coupled to a rotatable socket member. An impact assembly is configured to interface with the socket member to prevent rotation of the socket member relative to a tool body. Rotation of the jaws in a first direction allows the interaction of the jaws with the socket member to close the jaws. Likewise, the jaws open when they are rotated in a second direction. The impact assembly is formed of an annular impact ring, a spring, and a spring bearing member. A mechanism is provided which is configured to position the spring at a first length when the jaws are rotated relative to the socket member in a first direction and a second length when the jaws are rotated in a second direction. The variation of the spring length varies the force applied by the rotatable member to the jaws.  
         [0022]     In another embodiment of the invention, a chuck mechanism has a plurality of engageable jaws that are coupled to a socket member. An intermittently engageable impact bearing is configured to restrict rotation of the socket member upon activation, when the socket member is being rotated with the engageable jaws. The impact bearing is formed of an impact assembly, a spring and a first spring bearing member. The impact assembly is formed of an impact bearing ring and a second spring bearing member. The second spring bearing member is configured to axial move to adjust the force supplied from the spring to the impact bearing ring from a first spring force to a second spring force. The second spring bearing member applies the first spring force when the socket member is coupled to the impact assembly and the socket member is rotated in a first direction and the second spring force when the socket member is rotated in a second direction.  
         [0023]     In another embodiment of the invention, a chuck mechanism is disclosed having a plurality of engageable jaw elements. The engageable jaw elements are drivable in first and second directions. A socket member is disposed about the engageable jaw elements. An impact assembly is disposed adjacent to the socket member and is configured to intermittently apply anti-rotational forces to the socket member. The impact assembly has a thrust bearing member, a spring, and a spring support member. The spring support member is axially movable from a first location to a second location. The spring has a first length when the spring support member is in its first location and a second length when the spring bearing member is in its second location. This variation of length changes the anti-rotational force applied to the socket member.  
         [0024]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0026]      FIG. 1  is an exploded view of a prior art chuck mechanism;  
         [0027]      FIG. 2  is an exploded view of the first embodiment to the present invention;  
         [0028]      FIGS. 3-6  are sectional views of the chuck shown in  FIG. 2 ;  
         [0029]      FIG. 7  is an exploded view of a second embodiment to the present invention;  
         [0030]      FIGS. 8 and 9  are sectional views of the chuck mechanism shown in  FIG. 7 ;  
         [0031]      FIG. 10  is an exploded view of a third embodiment to the present invention;  
         [0032]      FIGS. 11-13  represent sectional views of the chuck shown in  FIG. 8 ;  
         [0033]      FIG. 14  is an exploded view of a chuck according to another embodiment to the present invention;  
         [0034]      FIGS. 15 and 16  represent sectional views of the chuck shown in  FIG. 14 ; and  
         [0035]      FIG. 17  represents a sectional view of an alternate chuck design. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0037]      FIG. 2  represents an exploded view of a chuck mechanism  20  according to the teachings of first embodiment to the invention. The chuck  20  includes a spindle  22  defining a bit accepting through bore  24 , a jaw assembly  26 , a socket  28 , and an impact assembly  31 . Intersecting the through bore  24  are bit engaging jaw elements  32  of the jaw assembly  26 . The jaw elements  32 , which have a bit engaging surface  34  and a threaded drive surface  36 , are slidably positioned within angularly disposed channels  38 .  
         [0038]     The spindle  22  can have a forward section  35 , a collar  37  and a rearward section  39 . The forward section  35  can have a center bit accepting through bore  24  formed therein, while the collar  37  can have a plurality of angularly disposed channels  38  formed therethrough which intersect the center through bore  24 . The rearward section can have a threaded hole  41 , which is adapted to threadingly engage an output spindle of a power tool (not shown).  
         [0039]     The socket assembly or socket  28  is annularly disposed about the jaw elements  32 . The socket  28  preferably defines an interior threaded bore  40 , which is configured to interface with the threaded drive surface  36  of the jaw elements  32 . Under normal operation of the tool, the socket  28  co-rotates with the jaw elements  32  and therefore does not move relative to the jaw elements  32 . To tighten or loosen the jaw elements  32 , the jaw assembly  26  is rotated relative to the socket  28 . This can occur by holding the socket  28  fixed and rotating the jaw assembly  26 .  
         [0040]     The relative rotation of the jaw assembly  26  causes the jaw elements  32  to move together though guideways  38  when the jaw assembly  26  is rotated in a first or tightening direction with respect to the socket  28  and to disengage when the jaw assembly  26  is rotated in a second or loosening direction relative to the socket  28 . The socket  28  is formed of two rings ( 42  and  44 ). The first ring  42  having the interior threaded surface  40  and a ramp interface surface  51 . The second ring  44  having a ramped surface  50  configured to interface with the ramp interface surface  51  of the first ring  42  and a plurality of engagement teeth  52 .  
         [0041]     The impact assembly  31  is rotationally fixed to the body of the tool and is configured to prevent or resist rotation of the socket  28  to drive the jaws  32 . The impact assembly  31  has an impact ring  54 , which has a plurality of engagement teeth  57  that are configured to interface with the corresponding engagement teeth  52  of the second ring  44 . The impact assembly  31  also has a spring  58  and a spring bearing element  60  which are configured to apply axial forces to the impact ring  54 .  
         [0042]     As best seen in  FIG. 3  (wherein some details of the  FIG. 2  embodiment have been omitted), when chucking a tool bit as described for the prior art, upon rotation of the jaw assembly  26  in the first or tightening direction, the threaded engagement between the jaws  32  and first ring  42  will initially cause first ring  42  to also rotate in the first direction. Second ring  44 , however, will be restrained from rotation by the engagement between teeth  52  and teeth  57 . Thus, first ring  42  will rotate relative to second ring  44  and ramped legs  51  will slide into the deep end  53  of ramped surface  50 . When ramped legs  51  are in the deep end of ramped surface  50  there can be no further relative rotation between first ring  42  and second ring  44 . At that point the impact ring  54  effectively engages first ring  42  via teeth  52  and  57  and via second ring  44 . Since first ring  42  is then prevented from rotating, there will be relative rotation between first ring  42  and jaw assembly  26  causing jaws  32  to move inward as described for the prior art. When the jaws  32  contact the shank of the bit and can no longer move axially the orbiting jaws  32  will then force first ring  42  to rotate, which in turn will cause second ring  44  to rotate.  
         [0043]     As shown in  FIG. 4 , during chucking, continued rotation of the jaw assembly  26  in the first or tightening direction will cause the rotationally coupled rings  42  and  44  to operate as in the prior art and will induce the reciprocating and impacting movement of impact ring  54  as previously described. In this preferred embodiment, however, the sloped interface  50  allows the interface ring  44  to move axially away from the spring bearing element  60  thus allowing the spring  58  to lengthen. This results in the spring  58  applying a smaller force to the impact ring  54  of the impact assembly  31 . This in turn results in a reduced tightening torque applied to the jaw elements  32  and bit interface when the jaw elements are engaging a bit.  
         [0044]     As best seen in  FIG. 5 , during unchucking of a drill bit, upon rotation of the jaw assembly  26  in the second or loosening direction, the threaded engagement between the jaws  32  and first ring  42  will initially cause first ring  42  to also rotate in the second direction. Second ring  44 , however, will be restrained from rotation by the engagement between teeth  52  and teeth  57 . Thus, first ring  42  will rotate relative to second ring  44  and ramped leg  51  will slide into the shallow end  55  of ramped surface  50 . When ramped legs  51  are in the shallow end of ramped surface  50  there can be no further relative rotation between first ring  42  and second ring  44 . At that point impact ring  54  effectively engages first ring  42  via teeth  52  and  57  and via second ring  44 .  
         [0045]     As seen in  FIG. 6 , continued rotation of the jaw assembly  26  in the second or loosening direction will cause rotationally interlocked first ring  42  and second ring  44  to initially rotate along with the jaw assembly  26 . Rotation of second ring  44  will cause the socket teeth  52  to ride over the ring teeth  57  and urge the impacting ring  54  in a rearward direction away from the threaded socket  28 . Since the spring  58  biases the impacting ring  54  forwardly, the socket teeth  52  will periodically strike the ring teeth  57  as the threaded socket  28  rotates. The impact of the socket teeth  52  and the ring teeth  57  will generate a torque that will eventually overcome the static friction between the first ring  42  and jaws  32 , at which point the first ring will break free of the jaws. Further rotation of the jaw assembly  26  will result in relative rotation between jaws  32  and first ring  42 , since rotation of first ring  42  is resisted via the interlocked second ring  44 , teeth  52  and  57 , and impact ring  54 . The continued relative rotation between rotating jaws  32  and nonrotating first ring  42  will cause the jaws to move axially rearward and outward, thus releasing the bit from the chuck. Advantageously in this embodiment, since second ring  44  was forced rearward when ramped leg  51  moved to the shallow end  55  of ramped surface  50 , spring  58  is compressed relative to its condition during chucking/tightening as described above. This results in the spring  58  applying a larger force to the impact ring  54  of the impact assembly  31  during unchucking. This in turn results in an increased loosening torque applied to the jaw elements  32  and bit interface when the jaw elements  32  are disengaging a bit.  
         [0046]      FIG. 7  represents an exploded view of the chuck assembly  70  according to another embodiment of the invention. Disposed about the spindle  22  and jaw elements  32  is a single piece socket  28 . The socket  28  defines a threaded through bore  40  which is configured to interface with the threaded drive surface  36  of the jaw elements  32 . The socket  28  has an interface surface  72  having a plurality of ramp engagement teeth  74 . As described above, an impact assembly  80  is configured to apply relative anti-rotational forces to the socket  28 . The impact assembly  80  has a impacting ring  82 , and first and second spring interface members  84  and  60 . Further disposed between the socket  28  and the impacting ring  82  is a biasing spring  29  that functions to separate the components when the drill is in drive mode.  
         [0047]     When a drill bit is to be chucked in the chuck assembly  70 , the top cover shell  112  of the housing is rotated to align the projections  86  on second spring interface members  84  with a deep locking recess  134  in the top cover shell  112 . The spring  58  urges the impacting ring  82  through spring interface member  84 , forwardly so that the ring teeth  71  engage the socket teeth  74 . The engagement of the ring teeth  71  engages the socket teeth  74  thereby resisting relative rotation between the impacting ring  82  and the threaded socket  28 . As the spring constant of biasing spring  29  is lower than spring  58 , it is compressed.  
         [0048]     As best seen in  FIG. 8 , subsequent rotation of the spindle  22  in a first rotational direction causes relative rotation between the spindle  22  and the threaded socket  28  that drives the jaw members  32  toward the rotational axis of the spindle  22  and tightens the jaw members  32  against the shank of the drill bit. Relative rotation of the impacting ring  82  in the first tightening direction with respect to the first spring interface member  84  causes the impacting ring  82  and the first spring interface member  84  to move together. This allows the spring member  58  to lengthen and reduces the force applied by the spring  58  to the impacting ring  82  and, therefore, the amount of force applied by the impacting ring  82  on the socket  28 . This reduces the amount of forces applied by the jaw drive&#39;s relative rotation with respect to the jaw elements  32  when the jaw elements are engaging a bit.  
         [0049]     The first spring interface member  84 , which is rotationally fixed, has a ramp surface  88  that interfaces with a corresponding ramp surface  89  on the impacting ring  82 . The ramped surface can be of the form of a recess (as shown in  FIGS. 8 and 9 , or a projection as shown in  FIG. 7 ). In this regard, the ramp surface  88  between the impacting ring  82  and the first spring interface member  84  are configured to allow restricted relative rotation therebetween.  
         [0050]     As previously described, continued rotation of the spindle  22  and jaws  32  will cause the socket  28  to begin to rotate with the spindle  22 , causing the socket teeth  74  to ride over the ring teeth  71  and urge the impacting ring  82  and first spring interface member  84  in a rearward direction away from the threaded socket  28 . Since the spring  58  biases the impacting ring  82  forwardly, the socket teeth  74  will periodically strike the ring teeth  71  as the threaded socket  28  rotates. The impact of the socket teeth  74  and the ring teeth  71  will generate a torque that is applied to the threaded socket  28 .  
         [0051]     As best seen in  FIG. 9 , during unchucking of a drill bit, upon rotation of the jaws  32  and spindle  22  in the second or loosening direction, the impacting member  82  is rotated in the second direction, the first spring interface member  84  is moved away from the impacting ring  82 , causing compression of the spring  58 . Due to the initial frictional forces, the socket teeth  74  may be caused to ride over the ring teeth  71  and urge the impacting ring  82  and first spring interface member  84  in a rearward direction away from the threaded socket  28 . Since the spring  58  biases the impacting ring  82  forwardly, the socket teeth  74  will periodically strike the ring teeth  71  as the threaded socket  28  rotates. The impact of the socket teeth  74  and the ring teeth  71  will generate a torque that is applied to the threaded socket  28 . This increases the force applied from the spring  58  to the impacting ring  82 . This in turn increases the amount of forces applied by socket  28  relative rotation with respect to the jaw elements  32 .  
         [0052]     The impact of the socket teeth  74  and the impacting teeth  71  will generate a torque that will eventually overcome the static friction between the socket  28  and jaws  32 , at which point the socket  28  will break free of the jaws  32 . Further rotation of the jaw spindle  22  and jaws  32  will result in relative rotation between jaws  32  and impacting ring  82 , since rotation of impacting ring  82  is resisted via the first spring interface member  84 , teeth  52  and  57 . The continued relative rotation between rotating jaws  32  and non-rotating impacting ring  82  will cause the jaws  32  to move axially rearward and outward, thus releasing the bit from the chuck.  
         [0053]     When the drill bit is to be normally driven in forward or reverse by the chuck assembly  70 , the top cover shell  112  of the housing is rotated to decouple the projections  86  on second spring interface members  84  from the deep locking recess  134  in the top cover shell  112 . This compresses spring  58  and allows spring  29  to urge the impacting ring  82  rearward so that the ring teeth  71  disengage the socket teeth  74  to thereby allowing rotation of the threaded socket  28  with the jaw elements  32 .  
         [0054]     With general reference to  FIGS. 10 and 14 , which represent chuck mechanisms  90  according to another embodiment of the invention. An impact assembly  92  is configured to apply rotational forces to the socket  28  to tighten or loosen the jaws depending on the rotational direction as described above.  
         [0055]     The impact assembly  92  is formed of an impacting ring  94 , a spring  58 , and a spring support member  96 . As previously mentioned, the impacting ring  94  has a plurality of ramp engagement teeth  98  configured to interface with the corresponding teeth  100  formed in the socket  28 . The spring support member  96  is axially moveable with respect to the socket  28  to alter the compression of the spring  58 . As best seen in  FIG. 11 , the spring support member  96  can be located in a first location which compresses the spring  58  to a first length allowing the spring to apply a first force on the impacting ring  94 . Alternatively, the spring support member  96  can be located in a second location (see  FIG. 12 ), which compresses the spring  58  to a second length, to apply a second force on the impacting ring  94 . As described, the first force being less than the second force.  
         [0056]     Annularly disposed about the spring support member  96  is a threaded member  102  which can be provided to allow a user to manually adjust the axial position of the spring support member  96 . Thus, rotation of the threaded member  102  allows the user to manually adjust the forces applied from the impact assembly  92  onto the socket  28  and jaw elements  32  to either tighten or loosen the jaw elements  32  with respect to the tool bit.  
         [0057]     As best seen in  FIGS. 14-17 , the spring support member  96  can alternatively be coupled to an annularly disposed housing  104  via a pair of support cam pins  106 . The support cam pins  106  are disposed within a pair of cam slots  108  formed in the support housing  104 . Rotation of the spring support member  96  in a first and forward direction places the cam pins  106  of the spring support plate in a first forward axial location, thus placing a first force on the impacting ring  94 .  
         [0058]     When the spring support member  96  is rotated into a second or reverse direction, the cam pins  106  of the spring support member  96  are positioned into a second location  110 , thus decreasing the amount of force applied by the springs  58  through the impacting ring and socket  28  onto the threads of the jaw elements  32 . As best seen in  FIG. 17 , the housing can optionally have a cam slot which allows complete disengagement of the impacting ring  94  from the socket  28 . In this way, the spring support  96  can be used to engage or disengage the self-tightening feature of the chuck.  
         [0059]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. For example, it is envisioned that mechanisms can vary the amount of force applied to the thrust bearing to the self-tightening chuck assembly depending upon whether the chuck is loosening or tightening jaws. These include varying the slope of the ramps of the interface between the thrust bearing and the jaw drive. Additionally, it is envisioned that the spring assembly can be formed of a plurality of spring elements, the actuation of which dependent upon whether the tool is in a drive, tight, or loose configuration. Such variations are not to be regarded as a departure from the spirit and scope of the invention.