Abstract:
A chuck including a body having a nose section with an axial bore formed therein, a plurality of jaws in communication with the axial bore, a sleeve rotatably mounted about the body in operative communication with the jaws, the sleeve defining an annular groove adjacent its rear perimeter, a rear cover defining an annular ridge that is received in the annular groove of the sleeve, and a bearing having a first race, a second race and at least one bearing element, wherein one of the first race and the second race defines a ratchet, wherein the other of the first race and the second race defines a pawl, the ratchet and the pawl are configured so that when the pawl engages the ratchet, the ratchet and pawl prevent the second race from rotating in the opening direction with respect to the first race.

Description:
CLAIM OF PRIORITY 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 61/702,777 filed Sep. 19, 2012, the entire disclosure of which is incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    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 
       [0003]    Both hand and electric or 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. 
         [0004]    A variety of chucks have been developed in the art. In an oblique jawed chuck, a chuck body includes three passageways disposed approximately 120° 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 which 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 onto 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. 
         [0005]    As well, many of these keyless chucks have been developed which include a locking feature that prevents inadvertent loosening, or possible opening, of the jaws. Many of these locking features require that an outer sleeve rotate relative to one or more spring-like pawls that are typically non-rotatably fixed to the nut. Through rotation of the sleeve relative to the pawls, the pawls can be made to either engage or disengage locking teeth that are fixed to the chuck body in some manner Because the sleeve must rotate relative to the pawls and nut, the sleeve cannot be press fit to the nut. Rather, the sleeve is typically, at least partially, supported on the pawls the sleeve operates. As noted, because the pawls must be movable radially inwardly and outwardly to function, they typically have a spring-like construction. Support of the outer sleeve on the spring-like pawls can lead to undesired radial motion, or wobbling, during normal operation of the chuck. 
         [0006]    To assist in preventing this undesired motion, some chucks include dust caps which are typically press-fit to a rear portion of the chuck body and have an outer perimeter that forms a gap with an inner surface of the rear perimeter of the sleeve. The size of this gap helps to limit the amount of radial motion of the sleeve relative to the chuck body. However, difficulties in manufacturing close tolerances between the outer perimeter of the dust cap and rear perimeter of the sleeve exist due to the size of the components. As well, it is not uncommon for the rear perimeter of the sleeves in these types of chucks to be slightly out-of-round due to the materials they are constructed from and the fact that the rear perimeter of the sleeve does not receive any direct structural support. 
         [0007]    The present invention recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods. 
       SUMMARY OF THE INVENTION 
       [0008]    One embodiment of a chuck in accordance with the present disclosure includes a generally cylindrical body having a nose section and a tail section, the tail section being configured to rotate with the drive shaft and the nose section having an axial bore formed therein, a plurality of jaws movably disposed with respect to the body in communication with the axial bore, a sleeve rotatably mounted about the body in operative communication with the jaws so that rotation of the sleeve in a closing direction moves the jaws toward the axis of the axial bore and rotation of the sleeve in an opening direction moves the jaws away from the axis, the sleeve defining an annular groove adjacent its rear perimeter, a rear cover defining an annular ridge extending radially outwardly from its annular outer surface, the annular ridge being received in the annular groove of the sleeve, and a bearing having a first race adjacent the body, a second race adjacent the sleeve and at least one bearing element disposed between the first race and the second race. One of the first race and the second race defines a ratchet, wherein the other of the first race and the second race defines a pawl, and the ratchet and the pawl are configured so that when the pawl engages the ratchet, the ratchet and pawl prevent the second race from rotating in the opening direction with respect to the first race. 
         [0009]    Another embodiment of a chuck in accordance with the present disclosure includes a body having a nose section and a tail section, the tail section being configured to rotate with the drive shaft and the nose section having an axial bore formed therein, a plurality of jaws movably disposed with respect to the body in communication with the axial bore, a sleeve rotatably mounted about the body in operative communication with the jaws so that rotation of the sleeve in a closing direction moves the jaws toward the axis of the axial bore and rotation of the sleeve in an opening direction moves the jaws away from the axis, the sleeve defining a recess adjacent its rear perimeter, a rear cover defining a projection extending radially outwardly from its annular outer surface, the projection being received in the recess of the sleeve, and a bearing having a first race adjacent the body, a second race adjacent the sleeve and at least one bearing element disposed between the first race and the second race, wherein one of the first race and the second race defines a ratchet. The other of the first race and the second race defines a pawl, and the ratchet and the pawl are configured so that when the pawl engages the ratchet, the ratchet and pawl prevent the second race from rotating in the opening direction with respect to the first race. 
         [0010]    Yet another embodiment of a chuck in accordance with the present disclosure includes a body having a nose section and a tail section, the tail section being configured to rotate with the drive shaft and the nose section having an axial bore formed therein, a plurality of jaws movably disposed with respect to the body in communication with the axial bore, a nut 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 sleeve rotatably mounted about the body in operative communication with the nut, the sleeve defining an annular groove adjacent its rear perimeter, a rear cover received in the sleeve in a press-fit adjacent a rear perimeter of the sleeve, and a bearing having a first race adjacent the body, a second race adjacent the sleeve and at least one bearing element disposed between the first race and the second race. One of the first race and the second race defines a ratchet, wherein the other of the first race and the second race defines a pawl, and the ratchet and the pawl are configured so that when the pawl engages the ratchet, the ratchet and pawl prevent the second race from rotating in the opening direction with respect to the first race. 
         [0011]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and, together with the description, serve to explain the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A full and enabling disclosure of the present invention, including the best mode thereof to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, which makes reference to the accompanying figures, in which: 
           [0013]      FIG. 1  is a longitudinal view, partly in section, of a chuck in accordance with an embodiment of the present disclosure; 
           [0014]      FIG. 2  is an exploded view of a chuck as shown in  FIG. 1 ; 
           [0015]      FIG. 3  is an exploded view of the bearing and nut of the chuck as shown in  FIG. 1 ; 
           [0016]      FIG. 4  is a partial perspective view of the sleeve of the chuck as shown in  FIG. 1 ; 
           [0017]      FIG. 5A  is a partial perspective view of the bearing and sleeve of the chuck as shown in  FIG. 1 ; 
           [0018]      FIG. 5B  is a partial perspective view of the bearing and sleeve of the chuck as shown in  FIG. 1 ; 
           [0019]      FIG. 6  is a partial cross-sectional view of the chuck as shown in  FIG. 1 , taken along line  7 - 7 ; and 
           [0020]      FIG. 7  is an exploded view of a chuck in accordance with an alternate embodiment of the present invention. 
       
    
    
       [0021]    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 PREFERRED EMBODIMENTS 
       [0022]    Reference will now be made in detail to presently preferred embodiments of the disclosure, 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 disclosure without departing from the scope or 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 disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
         [0023]    Referring to  FIGS. 1 and 2 , a chuck  10  includes a body  14 , a nut  16 , an outer sleeve  18 , a rear cover  12 , a nose piece  20  and a plurality of jaws  22 . Body  14  is generally cylindrical in shape and comprises a nose or forward section  24  and a tail or rearward section  26 . Nose section  24  has a front face  28  transverse to the longitudinal center axis  30  of body  14  and a tapered surface  32  at its forward end. The nose section defines an axial bore  34  that is dimensioned somewhat larger than the largest tool shank that the tool is designed to accommodate. A threaded bore  36  is formed in tail section  26  and is of a standard size to mate with the drive shaft of a powered or hand driver (not shown). The bores  34 ,  36  may communicate at a central region  38  of body  14 . While a threaded bore  36  is illustrated, such bore could be replaced with a tapered bore of a standard size to mate with a tapered drive shaft. Furthermore, body  14  may be formed integrally with the drive shaft. 
         [0024]    Body  14  defines three passageways  40  to accommodate three jaws  22 . Each jaw is separated from the adjacent jaw by an arc of approximately 120°. The axes of passageways  40  and jaws  22  are angled with respect to the chuck center axis  30  such that each passageway axis travels through axial bore  34  and intersects axis  30  at a common point ahead of the chuck body. The jaws form a grip that moves radially toward and away from the chuck axis to grip a tool, and each jaw  22  has a tool engaging face  42  generally parallel to the axis of chuck body  14 . Threads  44 , formed on the jaw&#39;s opposite or outer surface, may be constructed in any suitable type and pitch. 
         [0025]    As illustrated in  FIGS. 1 and 2 , body  14  includes a thrust ring  46  that, in a preferred embodiment, may be integral with the body. It should be understood, however, that thrust ring  46  and body  14  may be separate components. Thrust ring  46  includes a plurality of jaw guideways  48  formed around its circumference to permit retraction of jaws  22  therethrough and also includes a ledge portion  50  to receive a bearing assembly as described below. Ledge portion  50  includes a first surface  47  and a second surface  49 . First surface  47  extends radially outwardly, and is perpendicular to, longitudinal center axis  30  of the chuck body. Second surface  49  extends axially along, and is concentric about, longitudinal center axis  30  of the chuck body. 
         [0026]    Nose piece  20  retains nut  16  against forward axial movement. The nose piece is press fit to body nose section  24 . It should be understood, however, that other methods of axially securing the nut on the body may be used. For example, the nut may be a two-piece nut held on the body within a circumferential groove on the outer circumference of the body, such as by a band holding the two pieces together. 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. 
         [0027]    Outer sleeve  18  is secured from movement in the forward axial direction by an annular shoulder  91  on nose piece  20 . A frustoconical section  95  at the rearward end of the nose piece facilitates movement of jaws  22  within the chuck. As well, the outer circumferential surface of outer sleeve  18  may be knurled or may be provided with longitudinal ribs  77  or other protrusions to enable the operator to grip it securely. 
         [0028]    Additionally, the inner surface of outer sleeve  18  defines an annular groove  23  adjacent its rear perimeter  25 . Annular groove  23  is configured to receive an annular ridge  19  extending radially outwardly from an outer annular wall  17  of rear cover  12 . Rear cover  12  includes an inner annular wall  15  that defines a bore  21  that is configured to be slidably and rotatably received about rearward section  26  of chuck body  14 . After outer sleeve  18  has been positioned over chuck body  14  and retained in the forward axial direction by nose piece  20 , rear cover  12  is pressed into the rear perimeter  25  of outer sleeve  18  until annular ridge  19  is received in annular groove  23  in a snap-fit. So positioned, rear cover  12  serves to maintain the circular shape of rear perimeter  25  of outer sleeve  18 . As well, the reduced size of bore  21  and rear portion  26  of the chuck body, as opposed to the outer perimeter of a dust cover and rear perimeter of a sleeve on a typical chuck, allow for improved accuracy of manufacturing a gap between bore  21  and the rear portion of chuck body  14  to the desired tolerances. As such, since the gap between annular inner wall  15  and the outer surface of rear portion  26  can be manufactured with increased accuracy, unwanted radial motion of outer sleeve  18  relative to chuck body  14  can be reduced, as compared to typical locking chucks. 
         [0029]    The outer sleeve may be molded or otherwise fabricated from a structural plastic such as polycarbonate, a filled polypropylene, for example a glass filled polypropylene, or a blend of structural plastic materials. Other composite materials such as, for example, graphite filled polymerics may also be suitable in certain environments. Additionally, the outer sleeve may be fabricated from various metals. As should be appreciated by one skilled in the art, the materials for 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. 
         [0030]    Nut  16  has threads  56  for mating with jaw threads  44 . Nut  16  is positioned about the body in engagement with the jaw threads so that when the nut is rotated with respect to body  14 , the jaws will be advanced or retracted depending on the nut&#39;s rotational direction. 
         [0031]    As illustrated in  FIG. 3 , the nut&#39;s forward axial face includes recesses  62  that receive respective drive dogs  64  ( FIG. 2 ) extending from the inner surface of outer sleeve  18 . The angular width of the drive dogs is less than that of the recesses, resulting in a slight range of relative rotational movement, for example between 6° and 10°, between the nut and the outer sleeve. 
         [0032]    Nut  16  also defines a plurality of grooves formed as flats  68  about the nut&#39;s outer circumference. Flats  68  receive respective tabs  70  extending forward from an inner race  72  of a bearing assembly  74 . The engagement of tabs  70  and flats  68  rotationally fix the inner race to the nut, although it should be understood that there may be a slight rotational tolerance between the two. 
         [0033]    Inner race  72  receives a plurality of bearing elements  76 , in this case bearing balls, disposed between it and an outer race  78  seated on thrust ring ledge  50  ( FIG. 1 ). Outer race  78  is rotationally fixed to body  14  by a plurality of tabs  80  that extend inwardly from an inner periphery  81  of outer race  78 . The plurality of tabs  80  is received in corresponding grooves  82  defined by second surface  49  of the thrust ring ledge  50 . 
         [0034]    Outer race  78  also includes a ratchet. In the illustrated embodiment, the ratchet is formed by a plurality of sawtooth-shaped teeth  84  disposed about the inner circumferential surface of the outer race. A first pawl  86  extends from one side of each tab  70  and is biased radially outward from the inner race, thereby urging a distal end  88  of each first pawl  86  toward the outer race ratchet. 
         [0035]    Each tooth  84  has a first side with a slope approaching 90°. The second side has a lesser slope. First pawl  86  is deflectable and is generally disposed in alignment with the slope of the second side. Thus, rotation of inner race  72  in a direction  90  with respect to outer race  78  moves first pawl distal ends  88  repeatedly over teeth  84 , causing a clicking sound as ends  88  fall against each subsequent tooth&#39;s second side. This configuration of teeth  84  and first pawl  86 , however, prevents the inner race&#39;s rotation in an opposite direction  92 . Application of rotational force to the inner race in this direction forces distal ends  88  into the steep-sloped first sides of teeth  84 . Since first pawl  86  is generally perpendicular to the first sides, it does not deflect inward to permit rotation. 
         [0036]    As discussed below, direction  90  corresponds to the chuck&#39;s closing direction, while direction  92  corresponds to the chuck&#39;s opening direction. Accordingly, when first pawls  86  engage ratchet teeth  84 , the teeth permit the inner race&#39;s movement in the chuck&#39;s closing direction  90  but prevent its movement in the opening direction  92 . 
         [0037]    A second deflectable pawl  94  extends to the other side of each tab  70 . Like first pawls  86 , each second pawl  94  is biased radially outward. Unlike first pawls  86 , however, second pawls  94  do not engage the outer race ratchet. 
         [0038]    First and second pawls  86  and  94  include tabs  96  and  98  at their distal ends, respectively. Referring also to  FIG. 4 , an inner circumferential surface of outer sleeve  18  defines first and second recesses  100  and  102 . During the chuck&#39;s operation, each tab  98  is received in one of these recesses, depending on the sleeve&#39;s rotational position with respect to the nut, as discussed in more detail below. The sleeve also defines a third recess  104  and a cam surface  106 . Also depending on the sleeve&#39;s rotational position, each tab  96  is received either by cam surface  106  or by recess  104 . The sleeve includes a pair of recesses  100  and  102  for each tab  98  and a recess  104  and cam surface  106  for each tab  96 . 
         [0039]      FIG. 5B  illustrates the disposition of pawls  86  and  94  when sleeve  18  is in a first (disengaged) of two positions with respect to nut  16  ( FIG. 2 ), while  FIG. 5A  illustrates these components when the sleeve is in a second position (engaged) with respect to the nut. For ease of illustration, both figures omit the nut. However, referring to  FIG. 2  and to the sleeve&#39;s second position as shown in  FIG. 5A , each drive dog  64  is disposed against or adjacent to a side  108  of the gap  62  in which is it received. Each of the sleeve&#39;s recesses  102  receives tab  98  of one of the second pawls  94 , and each recess  104  receives tab  96  of one of the first pawls  86 . Accordingly, the distal end  88  of each first pawl  86  engages ratchet teeth  84 , and inner race  72  can rotate only in closing direction  90  with respect to outer race  78 . 
         [0040]    Referring now to  FIG. 5B , when inner race  72  moves in opening direction  92  with respect to the outer race, each tab  98  moves out of its recess  102  and into its recess  100 , as indicated by arrow  108 . Each tab  96  rides up and out of its recess  104  onto its cam surface  106 , as indicated by arrow  110 . As indicated by arrow  112 , this pushes each deflectable first pawl  86  radially inward, thereby disengaging distal ends  88  from ratchet teeth  84 . Thus, the inner race is free to rotate with respect to the outer race in either direction. 
         [0041]    As described in more detail below, when outer sleeve  18  rotates in opening direction  92  so that the inner race moves from the engaged position shown in  FIG. 5A  to the disengaged position shown in  FIG. 5B , drive dogs  64  move within grooves  62  of nut  16  ( FIG. 2 ) so that each drive dog is against or immediately adjacent to a side  110  of the groove. 
         [0042]    In operation, and referring to  FIGS. 2 ,  3 ,  5 A and  5 B, nut grooves  62  receive drive dogs  64  when the chuck is between fully opened and fully closed positions so that the drive dogs are adjacent groove sides  110 . Inner race  72  is disposed with respect to outer race  78  so that tabs  96  and  98  are received by cam surface  106  and recess  100 , respectively. That is, outer sleeve  18  is in the first position with respect to the nut. In this condition, tabs  98  and recesses  100  rotationally fix inner race  72  to outer sleeve  18 . Since inner race  72  is rotationally fixed to nut  16  by tabs  70  and flats  68 , an operator rotating outer sleeve  18  rotationally drives the nut through inner race  72 , thereby opening or closing the jaws. When the operator rotates the outer sleeve/bearing inner race/nut in the closing direction (indicated by arrow  90  in  FIG. 3 ) to the point that the jaws tighten onto a tool shank, the nut is urged rearward up the jaw threads, thereby pushing the nut against inner race  72 , bearing elements  76 , outer race  78  and thrust ring  46 . The rearward force creates a frictional lock between the nut and inner race  72  that further rotationally fixes two components. 
         [0043]    The wedge between the nut threads  56  and jaw threads  44  increasingly resists the nut&#39;s rotation. When the operator continues to rotate outer sleeve  18 , and the resistance overcomes the hold provided by tabs  98  in recesses  100 , outer sleeve  18  rotates with respect to nut  16  and inner bearing race  72 . This moves drive dogs  64  from sides  110  of grooves  62  to sides  108  and pushes tabs  98  out of recesses  100  into recesses  102 . Simultaneously, cam surfaces  106  rotate away from tabs  96  so that the tabs are released into recesses  104 , thereby engaging distal ends  88  of first pawls  86  with ratchet teeth  84 , as shown in  FIG. 5A . At this point, inner race  72 , and therefore nut  16 , is rotationally locked to outer race  78 , and therefore body  14 , against rotation in the chuck&#39;s opening direction  92 . That is, the nut is rotationally locked to the chuck body in the opening direction  92 . Since the nut&#39;s rotation with respect to the body is necessary to open the chuck, this prevents inadvertent opening during use. 
         [0044]    Inner race  72 , and therefore nut  16 , may, however, still rotate with respect to outer race  78 , and therefore body  14 , in the chuck&#39;s closing direction  90 . During such rotation, sleeve  18  drives nut  16  through drive dogs  64  against groove sides  108 , as well as through inner race  72 . This continues to tighten the chuck and, as described above, produces a clicking sound to notify the operator that the chuck is in a fully tightened position. 
         [0045]    To open the chuck, the operator rotates outer sleeve  18  in the opposite direction. Outer sleeve  18  transfers this torque to inner race  72  at the engagement of tabs  96  and  98  in recesses  104  and  102 , respectively. Because first pawls  86  engage outer race  78 , which is rotationally fixed to the body, through the ratchet teeth, the inner race cannot rotate with the outer sleeve. Thus, upon application of sufficient torque in the opening direction  92 , outer sleeve  18  moves with respect to the inner race and the nut. This moves tabs  96  back up onto cam surfaces  106 , thereby disengaging distal ends  88  of first pawls  86  from ratchet teeth  84 . Tabs  98  move from recesses  102  into recesses  100 , and drive dogs  64  move from sides  108  to sides  110  of grooves  62 . Thus, the sleeve moves to its first position with respect to the nut, as shown in  FIG. 5B , and the inner race and the nut are free to rotate with respect to the outer race and chuck body. Accordingly, further rotation of sleeve  18  in opening direction  92 ,moves jaws  22  away from the chuck axis, thereby opening the chuck. 
         [0046]    Referring now to  FIG. 7 , chuck  10  is shown with alternate embodiment of an outer race  78   a  for use in bearing assembly  74 . In contrast to the earlier described embodiment, outer race  78   a  does not include a plurality of tabs extending inwardly from an inner periphery  81  though. As well, second surface  49  of ledge portion  50  of chuck body  14  does not define a plurality of recesses. Rather than rotationally fixing outer race  78   a  to chuck body  14  with tabs and corresponding recesses, frictional forces are used to selectively fix outer race  78   a  to chuck body  14  while operating the chuck, as described below. 
         [0047]    In operation, and referring to  FIGS. 3 ,  5 A,  5 B, and  7 , nut grooves  62  receive drive dogs  64  when the chuck is between fully opened and fully closed positions so that the drive dogs are adjacent groove sides  110 . Inner race  72  is disposed with respect to outer race  78   a  so that tabs  96  and  98  are received by cam surface  106  and recess  100 , respectively. That is, outer sleeve  18  is in the first position (disengaged) with respect to the nut. In this condition, tabs  98  and recesses  100  rotationally fix inner race  72  to outer sleeve  18  and outer race  78  is free to rotate about body  14 . Since inner race  72  is rotationally fixed to nut  16  by tabs  70  and flats  68 , an operator rotating outer sleeve  18  rotationally drives the nut through inner race  72 , thereby opening or closing the jaws. When the operator rotates the outer sleeve/bearing inner race/nut in the closing direction (indicated by arrow  90  in  FIG. 3 ) to the point that the jaws tighten onto a tool shank, the nut is urged rearward up the jaw threads, thereby pushing the nut against inner race  72 , bearing elements  76 , outer race  78   a  and thrust ring  46 . The rearward force creates a frictional lock between the nut and inner race  72  that further rotationally fixes two components. Additionally, the rearward force increases the frictional forces between the rear surface of outer race  78   a  and first surface  47  of ledge portion  50 , in a direction opposite to the direction that outer sleeve  18  and nut  16  are being rotated. Eventually, the frictional forces restrain rotation of outer race  78   a  with respect to body  14 . Bearing balls  76 , however, permit sleeve  18  and nut  16  to continue to rotate relative to body  14  and outer race  78   a  in closing direction  90 . 
         [0048]    The wedge between nut threads  56  and jaw threads  44  increasingly resists the nut&#39;s rotation. When the operator continues to rotate outer sleeve  18 , and the resistance overcomes the hold provided by tabs  98  in recesses  100 , sleeve  18  rotates with respect to nut  16  and inner bearing race  72 . This moves drive dogs  64  from sides  110  of grooves  62  to sides  108  and pushes tabs  98  out of recesses  100  into recesses  102 . Simultaneously, cam surfaces  106  rotate away from tabs  96  so that the tabs are released into recesses  104 , thereby engaging distal ends  88  of first pawls  86  with ratchet teeth  84 , as shown in  FIG. 5A . At this point, inner race  72 , and therefore nut  16 , is rotationally locked to outer race  78   a,  and therefore body  14 , against rotation in the chuck&#39;s opening direction  92 . That is, the nut is rotationally locked to the chuck body in the opening direction. Since the nut&#39;s rotation with respect to the body is necessary to open the chuck, this prevents inadvertent opening during use. 
         [0049]    Inner race  72 , and therefore nut  16 , may, however, still rotate with respect to outer race  78   a,  and therefore body  14 , in the chuck&#39;s closing direction  90 . During such rotation, sleeve  18  drives nut  16  through drive dogs  64  against groove sides  108 , as well as through inner race  72 . This continues to tighten the chuck and, as described above, produces a clicking sound to notify the operator that the chuck is in a fully tightened position. 
         [0050]    To open the chuck, the operator rotates outer sleeve  18  in the opposite direction. Sleeve  18  transfers this torque to inner race  72  at the engagement of tabs  96  and  98  in recesses  104  and  102 , respectively. Because first pawls  86  engage outer race  78   a,  which is rotationally fixed to the body by frictional force, through the ratchet teeth, the inner race cannot rotate with the sleeve. Thus, upon application of sufficient torque in opening direction  92 , outer sleeve  18  moves with respect to the inner race and the nut. This moves tabs  96  back up onto cam surfaces  106 , thereby disengaging distal ends  88  of first pawls  86  from ratchet teeth  84 . Tabs  98  move from recesses  102  into recesses  100 , and drive dogs  64  move from sides  108  to sides  110  of grooves  62 . Thus, the outer sleeve moves to its first position with respect to the nut, as shown in  FIG. 5B , and the inner race and nut are free to rotate with respect to outer race  78   a  and chuck body. Accordingly, further rotation of outer sleeve  18  in the opening direction moves jaws  22  away from the chuck axis, thereby opening the chuck. As well, as nut  16  is rotated in the opening direction  92  and rearward force on jaws  22  is relieved, the frictional forces locking outer race  78   a  to first surface  47  are reduced to the point that outer race  78   a  is free to rotate about the chuck&#39;s body. 
         [0051]    In an alternate embodiment of the chuck, inner periphery  81  of outer race  78   a  and second surface  49  of ledge portion  50  are sized such that outer race  78   a  is received about body in a press-fit. This embodiment functions in a manner similar to that shown in  FIG. 2 , and previously described. As such, a description of the operation is not repeated here. 
         [0052]    While one or more preferred embodiments of the present disclosure have been described above, it should be understood that any and all equivalent realizations of the present disclosure are included within the scope and spirit thereof. Thus, the depicted embodiment(s) are presented by way of example only and are not intended as limitations. It should be understood that aspects of the various one or more embodiments may be interchanged either in whole or in part. Therefore, it is contemplated that any and all such embodiments are included in the present disclosure as may fall within the literal or equivalent scope of the appended claims.