Patent Publication Number: US-7722054-B2

Title: Chuck with torque indicator

Description:
CLAIM OF PRIORITY 
   This application is a continuation of U.S. patent application Ser. No. 10/834,403, filed Apr. 29, 2004, the entire disclosure of which is incorporated by reference herein. 

   FIELD OF THE INVENTION 
   The present invention relates generally to chucks for use with drills or with electric or pneumatic power drivers. More particularly, the present invention relates to a chuck of the keyless type which may be tightened or loosened by hand or actuation of the driver motor. 
   BACKGROUND OF THE INVENTION 
   Hand, electric and pneumatic tool drivers are well known. Although twist drills are the most common tools on such drivers, the tools may also comprise screw drivers, nut drivers, burrs, mounted grinding stones, and other cutting or abrading tools. Since the tool shanks may be of varying diameter or of polygonal cross section, the device is usually provided with a chuck adjustable over a relatively wide range. The chuck may be attached to the driver by a threaded or tapered bore. 
   A variety of chucks have been developed in the art. In an oblique jawed chuck, a chuck body includes three passageways disposed approximately 120 degrees apart from each other. The passageways are configured so that their center lines meet at a point along the chuck axis forward of the chuck. The passageways constrain three jaws that are moveable in the passageways to grip a cylindrical or polygonal tool shank displaced approximately along the chuck center axis. The chuck includes a nut that rotates about the chuck center and that engages threads on the jaws so that rotation of the nut moves the jaws in either direction within the passageways. The body is attached to the drive shaft of a driver and is configured so that rotation of the body in one direction with respect to the nut forces the jaws into gripping relationship with the tool shank, while rotation in the opposite direction releases the gripping relationship. The chuck may be keyless if it is rotated by hand. Various configurations of keyless chucks are known in the art and are desirable for a variety of applications. 
   SUMMARY OF THE INVENTION 
   The present invention recognizes and addresses considerations of prior art constructions and methods. In one embodiment of the present invention, a chuck has a generally cylindrical body having a nose section and a tail section, the tail section being configured to rotate with the drive shaft of the driver and the nose section has an axial bore formed therein. A plurality of jaws are movably disposed with respect to the body and are in communication with the axial bore. A nut is rotatably mounted about the body and is in operative communication with the jaws so that rotation of the nut in a closing direction moves the jaws toward the axis of the axial bore and rotation of the nut in an opening direction moves the jaws away from the axis. A generally cylindrical first sleeve is rotatably mounted about the body and is in driving engagement with the nut. The chuck also includes a tightening indicator having a first ring received intermediate the nut and the body and a second ring that rotates relative to the first sleeve over a limited arc. Additionally, one of the first ring and the second ring defines a ratchet and the other of the first ring and the second ring defines at least one deflectable pawl biased toward the ratchet. Moreover, the first ring is rotationally coupled to the second ring in the closing direction until the jaws clamp onto a tool shank; thereinafter, the first ring is rotationally fixed to the chuck body so that the second ring is rotatable relative to the first ring in the closing direction. 
   In another embodiment, a chuck has a generally cylindrical body having a nose section and a tail section, the tail section being configured to rotate with the drive shaft of the driver and the nose section having an axial bore formed therein. A plurality of jaws is movably disposed with respect to the body in communication with the axial bore. A nut is rotatably mounted about the body and in operative communication with the jaws so that rotation of the nut in a closing direction moves the jaws toward the axis of the axial bore and rotation of the nut in an opening direction moves the jaws away from the axis. A generally cylindrical sleeve is rotatably mounted about the body and in driving engagement with the nut. The chuck also has a tightening torque indicator having a plurality of equally spaced recesses that travel with one of the nut and the body and at least one deflectable pawl that travel with the other of the nut and the body. The at least one deflectable pawl is biased toward and received in one of the plurality of equally spaced recesses. Movement of the at least one deflectable pawl from the one of the plurality of equally spaced recesses to an adjacent one of the plurality of equally spaced recesses corresponds to a predetermined input torque on the nut that results in a predetermined output gripping force between the plurality of jaws. 
   The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended drawings, in which: 
       FIG. 1  is an exploded view of a chuck in accordance with an embodiment of the present invention; 
       FIG. 2  is a longitudinal view, in cross section, of the chuck shown in  FIG. 1 ; 
       FIG. 3A  is a partially exploded perspective view of the chuck shown in  FIG. 1  with the sleeve and nut shown in a clamped position; 
       FIG. 3B  is a partially exploded perspective view of the chuck shown in  FIG. 1  with the sleeve and nut shown in a released position; 
       FIG. 4  is an exploded view of a chuck in accordance with an embodiment of the present invention; 
       FIG. 5  is a longitudinal view, in cross section, of the chuck shown in  FIG. 4 ; 
       FIG. 6  is an exploded view of a chuck in accordance with an embodiment of the present invention; 
       FIG. 7  is a longitudinal view, in cross section, of the chuck shown in  FIG. 6 ; 
       FIGS. 8A and 8B  are bottom plan views of a chuck in accordance with an embodiment of the present invention; and 
       FIGS. 9A-9C  are bottom plan views of the chuck shown in  FIG. 6 . 
   

   Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to presently preferred embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope and spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
   Referring to  FIGS. 1 and 2 , a chuck  10  in accordance with the present invention includes a body  12 , a gripping mechanism, generally  14 , a front sleeve  18 , a nose piece  20 , a rear sleeve  24  and a nut  28 . In the embodiment illustrated, gripping mechanism  14  includes a plurality of jaws  26 . Body  12  is generally cylindrical in shape and comprises a nose or forward section  30  and a tail or rearward section  32 . An axial bore  34  formed in forward section  30  is dimensioned somewhat larger than the largest tool shank that chuck  10  is designed to accommodate. A threaded bore  36  ( FIG. 2 ) is formed in tail section  32  and is of a standard size to mate with a drive shaft of a powered or hand driver, for example a power drill having a spindle. The bores  34  and  36  may communicate at a central region of body  12 . While a threaded bore  36  is illustrated, such bore is interchangable with a tapered bore of a standard size to mate with a tapered drive shaft. Furthermore, body  12  may be formed integrally with the drive shaft. 
   Body  12  defines three passageways  38  that accommodate jaws  26 . Each jaw is separated from each adjacent jaw by an arc of approximately 120 degrees. The axis of passageways  38  and jaws  26  are angled with respect to the chuck center axis  40  such that each passageway axis travels through axial bore  34  and intersects axis  40  at a common point. Each jaw  26  has a tool engaging face  42  generally parallel to chuck axis  40  and threads  44  formed on the jaw&#39;s opposite or outer surface that may be constructed in any suitable type and pitch. Body  12  includes a thrust ring member  46  which, in a preferred embodiment, may be integral with body  12 . In an alternate embodiment, thrust ring member  46  may be a separate component from body  12  that is axially and rotationally fixed to the chuck body by interlocking tabs, press fitting or other suitable connection means. Thrust ring member  46  includes a plurality of jaw guideways  48  formed around its circumference to permit retraction of jaws  26  therethrough and also includes a ledge portion  50  to receive a bearing assembly as described below. 
   Body tail section  32  includes a knurled surface  52  that receives rear sleeve  24  in a press fit fashion. Rear sleeve  24  could also be retained through a press fit without knurling, by use of a key or by crimping, staking, riveting, threading or any other suitable method of securing the sleeve to the body. Further, the chuck may be constructed with a single sleeve having no rear sleeve, for example where the power driver to which the chuck is attached includes a spindle lock feature to enable actuation of the chuck by the single sleeve when the spindle is rotationally fixed by the spindle lock. 
   Nut  28 , which in the preferred embodiment is a split nut, defines female threads  54  located on an inner circumference of the nut and is received in a groove  56  formed in chuck body  12  proximate thrust ring member  46 . A bearing washer  62  and an annular bearing cage  58  are received between thrust ring  46  and nut  28 . Bearing cage  58  holds a plurality of balls  60  that permits the nut to rotate relative to the chuck body. 
   Nut  28  is shown in  FIG. 1  without serrations or knurling on its outer circumference. However, it should be understood that nut  28  may be formed with axially-aligned teeth, or other forms of knurling, on its outer circumference, and its outer edges may be provided with a small chamfer  66  to facilitate press fitting of the nut into a bore  68  of front sleeve  18 . Preferably, the front sleeve is molded or otherwise fabricated from a structural plastic such as a polycarbonate, a filled polypropylene, e.g., glass-filled polypropylene, or a blend of structural plastic materials. Other composite materials such as graphite filled polymerics may also be suitable in certain environments. As should be appreciated by one skilled in the art, the materials from which the chuck of the present invention are fabricated will depend on the end use of the chuck, and the above materials are provided by way of example only. 
   The outer circumferential surface of front sleeve  18  may be knurled or may be provided with longitudinal ribs  70  or other protrusions to enable the operator to grip it securely. In like manner, the circumferential surface of rear sleeve  24  may be knurled or ribbed as at  72  if desired. Front sleeve  18  is press fit to nut  28  to rotationally and axially secure the sleeve to the nut. The press fitting of nose piece  20  to body nose section  30  also helps to retain sleeve  18  against forward axial movement. Nose piece  20  may be coated with a non-ferrous metallic coating to prevent rust and to enhance its appearance. Examples of suitable coatings include zinc or nickel, although it should be appreciated that any suitable coating could be utilized. 
   Because sleeve  18  is rotationally fixed to nut  28 , the sleeve&#39;s rotation with respect to body  12  also rotates nut  28  with respect to the body, which moves jaws  26  axially within passageways  38  due to the engagement of jaw threads  44  and nut threads  54 . The direction of axial movement of jaws  26  depends on the rotational direction of sleeve  18  and nut  28  with respect to body  12 . If a tool, such as a drill bit, is inserted into bore  34 , the sleeve and nut may be rotated about chuck axis  40  in a closing direction  88  ( FIG. 3A ) so that jaws  26  move to a closed position wherein jaw tool engaging surfaces  42  grippingly engage the tool. Rotation of sleeve  18  and nut  28  about axis  40  in the opposite or opening direction  90  ( FIG. 3B ) moves the jaws axially rearward out of the closed position to an open position as illustrated in  FIG. 2 . 
   Chuck  10  includes a tightening torque indicator comprising an annular ring  74  and an annular ratchet  80 . Annular ring  74  defines an inwardly extending flange  76  and has pawls  78  that are connected to the ring via spring tabs  82 . Spring tabs  82  bias the pawls radially outward from chuck axis  40  into engagement with annular ratchet  80 . Annular ratchet  80  defines forwardly extending tabs  84  and a plurality of teeth  83  formed on an inner circumference of the main ratchet band. Each of teeth  83  has a first side with a slope approaching 90 degrees and a second side having a lesser slope, which allows pawls  78  to slip over the teeth in one direction but not in the opposite direction. 
   Annular ring  74  is received on chuck body  12  intermediate bearing washer  62  and thrust ring  46 . Annular ratchet  80  is received about annular ring  74  and nut  28  so that grooves  86  ( FIGS. 3A and 3B ) formed on the inner circumference of sleeve  18  receive respective tabs  84 . The width of grooves  86  is larger than the width of tabs  84  so that sleeve  18  is rotatable over a limited angular distance relative to annular ratchet  80 . 
   To close the chuck from an open condition, and referring to  FIG. 3A , nut  28  is rotated via sleeve  18  in closing direction  88  so that jaws  26  are threadedly moved axially forward within passageways  38 . Because tabs  84  sit against the driving edges of grooves  86 , annular ratchet  80  rotates in conjunction with sleeve  18 . Annular ring  74  also rotates with sleeve  18  since pawls  78  rotationally fix annular ring  74  to annular ratchet  80 . Once jaws  26  clamp onto a tool shank, however, a corresponding axial force is increasingly exerted rearwardly through jaws  26  to nut  28 . The rearward axial force is transmitted through nut  28  to chuck body  12 , and in particular against thrust ring member  46 . Because annular ring flange  76  is intermediate bearing washer  62  and thrust ring ledge  50 , axial force is transmitted from nut  28  through annular ring flange  76  to thrust ring member  46 . This increases frictional forces between annular ring flange  76 , bearing washer  62  and thrust ring member  46  in a direction opposite to the direction that sleeve  18  and nut  28  are being rotated. Accordingly, the frictional forces restrain rotation of annular ring  74  with respect to body member  12 . Bearing  58 , however, permits sleeve  18  and nut  28  to continue to rotate relative to chuck body  12  and annular ring  74  in the closing direction. Additionally, since pawls  78  are deflectable and are generally disposed in alignment with the shallow slopes of the second side of teeth  83 , annular ratchet  80  continues to rotate with sleeve  18  relative to annular ring  74 . Thus, as annular ratchet  80  rotates, the distal ends of pawls  78  repeatedly ride over teeth  83 , producing an audible clicking sound as the pawl ends fall against each subsequent tooth&#39;s second side. Pawls  78  are generally perpendicular to the first sides of teeth  83  and do not deflect inward to permit rotation of annular ratchet  80  in a direction opposite to  88 . That is, until the jaws clamp onto a tool shank, annular ring  74  rotates with annular ratchet  80 . Once the jaws clamp onto a tool shank, annular ratchet  80  rotates in the closing direction relative to annular ring  74  but is blocked from rotating in opening direction  90 . 
   To open chuck  10 , and referring particularly to  FIG. 3B , sleeve  18 , and therefore nut  28 , are rotated in direction  90  opposite to direction  88 . Because pawls  78  and ratchet teeth  83  constrain annular ratchet  80  in the opening direction, ring  80  initially does not move, and tabs  84  therefore move through grooves  86 . This slight rotation of nut  28  relative to chuck body  12  causes jaws  26  to retract slightly in passageways  38  and thereby releases the axially rearward force that frictionally retains annular ring flange  76  between bearing washer  62  and thrust ring member  46 . As a result, annular ring  74  is once again rotatable with respect to the body. As the user continues to rotate sleeve  18  in opening direction  90 , tabs  84  abut the sides of grooves  86  so that sleeve  18  again drives annular ratchet  80  and annular ring  74 . 
   Depending on the frictional engagement between sleeve  18  and ratchet ring  80 , if sleeve  18  is thereafter rotated in the closing direction, tabs  84  may rotate through grooves  86  until the tabs abut the opposite sides of the grooves, and the chuck may then be operated in the closing direction as described above. In the presently illustrated embodiment, however, friction between sleeve  18  and ring  80  hold the sleeve and the ring together in the position shown in  FIG. 3B  as the sleeve is rotated in closing direction  88  ( FIG. 3A ) until the jaws close onto a tool shank. When this event stops rotation of ring  74 , pawls  78  hold ratchet ring  80  in position until grooves  86  in the still-rotating sleeve  18  pass over tabs  84 . When the following edges of grooves  86  engage tabs  84 , the sleeve again drives ring  80 , and the chuck operates as discussed above. 
   In the embodiment illustrated in  FIG. 4 , chuck body  12  has been modified to receive a one piece nut  28 . Forward portion  30  of chuck body  12  has been narrowed to allow the one-piece nut to slip over the forward body section into operative engagement with jaws  26  and thrust ring  46 . That is, in assembling the chuck of  FIGS. 4 and 5 , annular ring  74 , bearing washer  62  and bearing retainer  58  are slipped onto chuck body  12  adjacent to thrust ring  46 . Next, jaws  26  are placed into respective passageways  38 , and one-piece nut  28  is placed into abutment with bearings  60 , so that the nut threads are in meshing engagement with the jaw threads. 
   A nut retainer  100  is received over forward body portion  30  in abutment with nut  28  to retain the nut in the axially forward direction. Nut retainer  100  includes a first generally cylindrical portion  102  that is press-fit onto the body and a second frusto-conical portion  104  that engages the nut while providing clearance for the jaws forward of the nut. Annular ratchet  80  is received about annular ring  74  so that pawls  78  engage teeth  83 . Front sleeve  18  is then loosely fitted over forward body section  30 . Drive ribs  19  (shown in phantom) formed on the inner circumference of front sleeve  18  engage drive slots  29  of nut  28 , and annular ratchet tabs  84  are received in grooves  86  so that front sleeve  18 , nut  28  and toothed ring  80  operate as described above. 
   A nose piece  20  is dimensioned and adapted to be press fitted onto the front of forward body section  30  to maintain front sleeve  18  on chuck  10 . It should be appreciated that nose piece  20  could also be secured by snap fit, threading, or the like. Nose piece  20  is exposed when the chuck is assembled and is preferably coated with a non-ferrous metallic coating to prevent rust and to enhance its appearance. In a preferred embodiment, such coating may be zinc or nickel; however, it should be appreciated that any suitable coating could be utilized. 
   Nose piece  20  serves to maintain front sleeve  18  in position on chuck body  10  and in driving engagement with nut  28 . In addition, nose piece  20  serves the dual purpose of providing an aesthetically pleasing cover for the nose portion that inhibits rust. This provides the advantage of an aesthetically pleasing appearance without the necessity to coat the entire chuck body  12  with a non-ferrous material. 
   The chuck of  FIGS. 4 and 5  operates substantially the same as the embodiment of  FIGS. 1 to 3 . Therefore, a discussion of the operation of the chuck and tightening indicator will not be repeated. 
     FIGS. 6 and 7  illustrate an embodiment of a chuck  10  having a sleeve  18   a  and an alternate tightening torque indicator. Parts of chuck  10  that have been changed from the previous embodiments have been assigned numerical labels ending with an “a”. Chucks having a single sleeve are generally used with drivers having a spindle lock so that the spindle can be rotationally fixed to the driver while the sleeve is rotated in the opening or closing direction. Spindle locks should be well understood in the art. Spindle locks do not form a part of the present invention and are not discussed in further detail herein. It should be understood, however, that the chuck of the embodiment shown in  FIGS. 6-9  would generally be used with a power driver having a spindle lock. 
   Chuck  10  has a body  12 , a gripping mechanism, generally  14 , sleeve  18   a , a nose piece  20 , a rear disc  25  and a nut  28 . Gripping mechanism  14  includes a plurality of jaws  26 . Body  12  is generally cylindrical in shape and comprises a nose or forward section  30  and a tail or rearward section  32 . An axial bore  34  formed in forward section  30  is dimensioned somewhat larger than the largest tool shank that chuck  10  is designed to accommodate. A threaded bore  36  ( FIG. 7 ) is formed in tail section  32  and is of a standard size to mate with a drive shaft of a powered or hand driver, for example a power drill having a spindle. The bores  34  and  36  may communicate at a central region of body  12 . While a threaded bore  36  is illustrated, such bore is interchangeable with a tapered bore of a standard size to mate with a tapered drive shaft. Furthermore, body  12  may be formed integrally with the drive shaft. 
   Body  12  defines three passageways  38  that accommodate jaws  26 . Each jaw is separated from each adjacent jaw by an arc of approximately 120 degrees. The axes of passageways  38  and jaws  26  are angled with respect to the chuck center axis  40  such that each passageway axis travels through axial bore  34  and intersects axis  40  at a common point. Each jaw  26  has a tool engaging face  42  generally parallel to chuck axis  40  and threads  44  formed on the jaw&#39;s opposite or outer surface that may be constructed in any suitable type and pitch. 
   Body  12  includes a thrust ring member  46  which, in a preferred embodiment, may be integral with body  12 . In an alternative embodiment, thrust ring member  46  may be a separate component from body  12  that is axially and rotationally fixed to the chuck body by interlocking tabs, press fitting or other suitable connection means. Thrust ring member  46  includes a plurality of jaw guideways  48  formed around its circumference to permit retraction of jaws  26  therethrough and also includes a ledge portion  50  to receive a bearing assembly as described below. 
   Body tail section  32  includes a knurled surface  52  that receives rear disc  25  in a press fit fashion. Rear disc  25  could also be retained through a press fit without knurling, by use of a key or by crimping, staking, riveting, threading or any other suitable method of securing the disc to the body. 
   Nut  28 , which in the preferred embodiment is a split nut, defines female threads  54  located on an inner circumference of the nut and is received in a groove  56  formed in chuck body  12  proximate thrust ring member  46 . A bearing washer  62  and an annular bearing cage  58  are received between thrust ring  46  and nut  28 . Bearing cage  58  holds a plurality of balls  60  that permits the nut to rotate relative to the chuck body. 
   Nut  28  is shown in  FIG. 6  without serrations or knurling on its outer circumference. However, it should be understood that nut  28  may be formed with axially-aligned teeth, or other forms of knurling, on its outer circumference, and its outer edges may be provided with a small chamfer  66  to facilitate press fitting of the nut into a bore  68  of sleeve  18   a . Preferably, the sleeve is molded or otherwise fabricated from a structural plastic such as a polycarbonate, a filled polypropylene, e.g., glass-filled polypropylene, or a blend of structural plastic materials. Other composite materials such as graphite filled polymerics may also be suitable in certain environments. As should be appreciated by one skilled in the art, the materials from which the chuck of the present invention is fabricated will depend on the end use of the chuck, and the above materials are provided by way of example only. 
   An outer circumferential surface of sleeve  18   a  may be knurled or may be provided with longitudinal recesses  72  or other protrusions  70  to enable the operator to grip it securely. Sleeve  18   a  is press fit to nut  28  to rotationally and axially secure the sleeve to the nut. The press fitting of nose piece  20  to body nose section  30  also helps to retain sleeve  18   a  against forward axial movement. Nose piece  20  may be coated with a non-ferrous metallic coating to prevent rust and to enhance its appearance. Examples of suitable coatings include zinc or nickel, although it should be appreciated that any suitable coating could be utilized. 
   Because sleeve  18   a  is rotationally fixed to nut  28 , the sleeve&#39;s rotation with respect to body  12  also rotates nut  28  with respect to the body, which moves jaws  26  axially within passageways  38  due to the engagement of jaw threads  44  and nut threads  54 . The direction of axial movement of jaws  26  depends on the rotational direction of sleeve  18   a  and nut  28  with respect to body  12 . If a tool, such as a drill bit, is inserted into bore  34 , the sleeve and nut may be rotated about chuck axis  40  in a closing direction  88  ( FIG. 6 ) so that jaws  26  move to a closed position wherein jaw tool engaging surfaces  42  grippingly engage the tool. Rotation of sleeve  18   a  and nut  28  about axis  40  in the opposite or opening direction moves the jaws axially rearward out of the closed position to an open position as illustrated in  FIG. 7 . 
   Chuck  10  includes a tightening torque indicator comprising an annular ring  74   a  and an annular ratchet  80   a . Annular ring  74   a  defines an inwardly extending flange  76  and has four pawls  78  that are connected to the ring via spring tabs  82 . Spring tabs  82  bias the pawls radially outward from chuck axis  40  into engagement with annular ratchet  80   a . Annular ratchet  80   a  defines forwardly extending tabs  84  and a plurality of recessed grooves  83   a  formed on an inner circumference of the main ratchet band. It should be understood that the chuck of the present embodiment can function with at least one pawl, but the optimum audible click is achieved with between preferably three or four pawls depending on the number of grooves  83   a . That is, the number of grooves is preferably an equal multiple of the number of pawls so that each pawl simultaneously engages a corresponding groove. 
   As described in more detail below, and similarly to the embodiments described above, ring  74   a  can rotate with respect to ratchet  80   a  when the chuck jaws tighten onto a tool. As also similar to the above embodiments, such relative rotation between the ring and the ratchet produces an audible “clicking” sound as pawls  78  move from one set of grooves  83   a  to a succeeding set. In the present embodiment, however, grooves  83   a  are spread apart from each other so that the first such audible indicator occurs at a point at which a gripping torque applied by the jaws to the tool has been achieved that is sufficient to secure the tool in the chuck for expected normal operation without slipping of the tool in the jaws. Thus, the first clicking sound following the jaws&#39; engagement of the tool notifies the user that the desired tightening torque has been achieved and that the user may therefore stop tightening the chuck. Of course, the level of desired gripping torque might vary among different circumstances. Once the desired grip torque is defined, however, the degree to which the sleeve should be rotated to achieve the desired grip torque, and therefore the angular spacing between the adjacent grooves  83   a  needed to provide the first audible click at the desired grip torque, depends upon the chuck&#39;s design and construction. 
   Generally, for a given chuck design and construction, there exists a linear relationship between input torque applied to the sleeve and nut after the jaws grip a tool and grip torque applied by the jaws to the tool. Thus, a given input torque can be expected to result in a predictable grip force. The tables below provide test results showing measured input torque and resulting output torque. 
   
     
       
         
             
          
             
                 
             
             
               Test Results of Input Torque and Corresponding Output Torque 
             
          
         
         
             
             
             
             
          
             
                 
               Chuck Number 1 
               Chuck Number 2 
               Chuck Number 3 
             
          
         
         
             
             
             
             
             
             
             
          
             
                 
               Input 
               Output 
               Input 
               Output 
               Input 
               Output 
             
             
                 
               Torque 
               Torque 
               Torque 
               Torque 
               Torque 
               Torque 
             
             
               Measurement 
               (lbs-in) 
               (lbs-in) 
               (lbs-in) 
               (lbs-in) 
               (lbs-in) 
               (lbs-in) 
             
             
                 
             
          
         
         
             
             
             
             
             
             
             
          
             
               1 
               29 
               42 
               20 
               32 
               40 
               50 
             
             
               2 
               32 
               46 
               22 
               40 
               38 
               53 
             
             
               3 
               29 
               42 
               21 
               38 
               40 
               54 
             
             
               4 
               31 
               47 
               20 
               36 
               35 
               51 
             
             
               5 
               30 
               45 
               20 
               38 
               35 
               53 
             
             
               6 
               29 
               40 
               21 
               35 
               38 
               56 
             
             
               7 
               29 
               39 
               20 
               33 
               38 
               55 
             
             
               8 
               32 
               44 
               20 
               36 
               34 
               54 
             
             
               9 
               32 
               48 
               20 
               36 
               35 
               55 
             
             
               10  
               31 
               44 
               20 
               38 
               35 
               51 
             
             
               Avg. 
               30.4 
               43.7 
               20.4 
               32.7 
               36.8 
               53.2 
             
             
                 
             
          
         
       
     
   
   As shown above, the output gripping force of a chuck is generally proportional to the torque exerted on the nut through the sleeve as the sleeve is rotated in the closing direction once the jaws contact the tool shank. The proportional relationship between input torque and grip force for a given chuck depends upon design and construction factors, including but not limited to the thread pitch of the jaws and the nut, lubrication between the chuck&#39;s moving parts, finishes on the surfaces of the moving parts, the bearing system employed, the area of contact between abutting surfaces that move relative to each other, and the angle of the jaw passageways relative to the central axis of the body. Consequently, varying one or more of the above chuck characteristics can result in an increase or decrease in the ratio of input torque to output gripping force. 
   Thus, where the relationship between input torque and output grip force is known for a given chuck arrangement, the desired angular spacing between grooves  83   a  can be determined by measuring the rotation of the sleeve and nut needed to achieve an input torque that corresponds to the desired grip force. For example, with a tool shank placed in axial bore  34 , sleeve  18   a  may be rotated until the jaws engage the shank and the nut stops rotating relative to chuck body  12 . A torque wrench is then attached to sleeve  18   a , and the sleeve is rotated by the torque wrench in the closing direction until the input on the torque wrench reads approximately the target input torque. The angle between the torque wrench starting point and ending point is equal to the angular rotation the sleeve and nut must rotate to produce the required input torque to result in the desired output gripping force. For the chuck embodiment illustrated in  FIGS. 6-7 , the angular rotation is approximately 30 degrees ( FIG. 7 ). The last step is to determine the number of times the measured angle divides into 360 degrees. In the present example, 30 degrees goes into 360 degrees twelve times. Thus, annular ratchet  80   a  is formed with twelve recessed grooves  83   a  equally spaced about the inner circumference of the ratchet. 
   Of course, it is possible, and in fact likely, that the measured angle will not divide into 360 degrees by a whole number. In that event, the number of grooves is preferably at most the next lowest whole number. For example, assume that the angle measured by the torque wrench to achieve the desired grip is 25 degrees. Twenty five degrees divides into 360 degrees 14.4 times. At most, 14 grooves should preferably be provided in the sleeve. Fourteen grooves provide the spacing closest to that which corresponds to the desired input torque and gripping force. More than 14 evenly distributed grooves would result in a first click prior to the point at which the desired input and grip torque are achieved. Fewer than 14 evenly-spaced grooves would result in the user applying more torque than necessary to achieve the minimum desired grip torque, but such arrangements may be desirable. For example, the number of grooves  83   a  should be a whole multiple of the number of pawls  78  so that all pawls simultaneously engage respective grooves. Thus, assume in the above example that it is desired to have four pawls. Four does not divide evenly into 14, and the number of grooves would preferably be adjusted downward to 12 grooves, the first whole multiple of four that is less then 14. Thus, referring to  FIG. 8A , chuck  10  has 20 equally spaced grooves. Thus, the chuck required no more than 18 degrees of angular rotation to result in 20 equally spaced recessed grooves on ratchet  80   a . The chuck shown in  FIG. 8B  has 16 equally spaced grooves. Thus, the chuck required no more than 22.5 degrees of angular rotation to result in 16 equally spaced recessed grooves on ratchet  80   a.    
   Annular ring  74   a  is received on chuck body  12  intermediate bearing washer  62  and thrust ring  46 . Annular ratchet  80   a  is received about annular ring  74   a  and nut  28  so that grooves (not shown) formed on the inner circumference of sleeve  18   a  receives respective tabs  84 . The width of the grooves is larger than the width of tabs  84  so that sleeve  18   a  is rotatable over a limited angular distance relative to annular ratchet  80   a.    
   To close the chuck from an open condition, and referring to FIGS.  7  and  9 A- 9 C, nut  28  is rotated via sleeve  18   a  in closing direction  88  so that jaws  26  are threadedly moved axially forward within the jaw passageways. Because tabs  84  sit against the driving edges of the sleeve grooves, annular ratchet  80   a  rotates in conjunction with sleeve  18   a . Annular ring  74   a  also rotates with sleeve  18   a  since pawls  78  rotationally fix annular ring  74   a  to annular ratchet  80   a . Once jaws  26  clamp onto a tool shank, however, a corresponding axial force is increasingly exerted rearwardly through jaws  26  to nut  28 . The rearward axial force is transmitted through nut  28  to chuck body  12 , and in particular against thrust ring member  46 . Because annular ring flange  76  is intermediate bearing washer  62  and thrust ring ledge  50 , axial force is transmitted from nut  28  through annular ring flange  76  to thrust ring member  46 . This increases frictional forces between annular ring flange  76 , bearing washer  62  and thrust ring member  46  in a direction opposite to the direction that sleeve  18   a  and nut  28  are being rotated. Accordingly, the frictional forces restrain rotation of annular ring  74   a  with respect to body member  12  ( FIG. 9A ). 
   Referring to  FIG. 9B , however, bearing  58  permits sleeve  18   a  and nut  28  to continue to rotate relative to chuck body  12  and annular ring  74   a  in the closing direction. Additionally, since pawls  78  are deflectable and are generally disposed in alignment with the shallow sloped walls of recessed grooves  83   a , annular ratchet  80   a  continues to rotate with sleeve  18   a  relative to annular ring  74   a . Thus, as annular ratchet  80  rotates the distal end of pawls  78  ride over the flat inner surface of annular ratchet  80   a  between adjacent recessed grooves. Referring to  FIG. 9C , once the desired input torque has been applied to the sleeve/nut combination, each pawl  78  simultaneously enters a corresponding recessed groove  83   a  adjacent to the starting recessed groove, thereby producing an audible clicking sound indicating that the proper output gripping force has been achieved. That is, in the illustrated embodiment, in order for the audible click to occur, the sleeve/nut/annular ratchet combination must be rotated 30 degrees from the point where the jaws engaged the tool shank in order for the pawls to move from one recessed groove to the next adjacent groove. 
   To open chuck  10 , and referring particularly to  FIGS. 9A-9C , sleeve  18   a , and therefore nut  28 , are rotated in an opposite direction to direction  88 . Because pawls  78  and recessed grooves  83   a  constrain annular ratchet  80   a  in the opening direction, ring  80   a  initially does not move, and tabs  84  therefore move through the sleeve grooves. This slight rotation of nut  28  relative to chuck body  12  causes jaws  26  to retract slightly in passageways  38  and thereby releases the axially rearward force that frictionally retains annular ring flange  76  between bearing washer  62  and thrust ring member  46 . As a result, annular ring  74   a  is once again rotatable with respect to the body. As the user continues to rotate sleeve  18   a  in the opening direction, tabs  84  abut the sides of the sleeve grooves so that the sleeve again drives annular ratchet  80   a  and annular ring  74   a.    
   If sleeve  18  is thereafter rotated in the closing direction, friction between sleeve  18  and ring  80  hold the sleeve and the ring together in the position they were in the opening direction until the jaws close onto a tool shank. When this event stops rotation of ring  74 , pawls  78  hold ratchet ring  80  in position until grooves  86  in the still-rotating sleeve  18  pass over tabs  84 . When the following edges of grooves  86  engage tabs  84 , the sleeve again drives ring  80 , and the chuck operates as discussed above. 
   It should be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention. For example, the tightening torque indicator shown in  FIGS. 6-8  can be employed in the dual sleeve shucks shown in  FIGS. 1-5 . It is intended that the present invention cover such modifications and variations as come within the scope and spirit of the appended claims and their equivalents.