Abstract:
A motor driven ratchet wrench has a ratchet gear, oscillating pawl and pawl driver components situated in a sealed housing at the head end of the wrench. Premature wearing of parts is avoided as dirt cannot enter and lubricant does not escape. Frequent cleaning and relubrication is unnecessary. Internal components of the pawl, pawl driver and directional control for reversing the angular direction of the torque which is applied to threaded fasteners have configurations which enable the head end of the sealed wrench to be compact as is advantageous for use of the wrench is constricted locations.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims subject matter disclosed in U.S. Provisional Application No. 60/500,380 entitled “Power Ratchet Head” and which was filed on Sep. 5, 2003 by Kevin Brun. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT (Not Applicable)  
     BACKGROUND OF THE INVENTION  
       [0002]     This invention relates to ratchet wrenches for tightening and loosening nuts, bolts or other threaded fasteners. More particularly, the invention relates to ratchet wrenches which have pawl and ratchet means for applying a repetitive torque force to threaded fasteners in response to rotation of a motor driven crankshaft.  
         [0003]     Powered ratchet wrenches greatly facilitate automotive repair work, manufacturing procedures and various other operations where threaded fasteners must be engaged or disengaged. Among other advantages, the operator of the wrench need not exert the sizable force that may be needed to tighten or loosen a threaded fastener. The powered wrench may be used in constricted spaces where it may not be practical to pivot a wrench manually in order to engage or disengage the fastener.  
         [0004]     Powered ratchet wrenches greatly facilitate automotive repair work, manufacturing procedures and various other operations where threaded fasteners must be engaged or disengaged. Among other advantages, the operator of the wrench need not exert the sizable force that may be needed to tighten or loosen a threaded fastener. The powered wrench may be used in constricted spaces where it may not be practical to pivot a wrench manually in order to engage or disengage the fastener.  
         [0005]     Powered ratchet wrenches have a ratchet gear which is rotated through repetitive angular increments by pawl mechanism that oscillates in response to continuous turning of a crankshaft. The crankshaft is driven by a pneumatic or electrical motor. Many wrenches also have internal components which enable selectively reversing of the direction of rotation of the ratchet gear. In prior wrench designs some or all of these mechanisms are exposed to the external environment through various openings at the head end of the wrench. Dirt and other foreign materials can enter and contaminate the mechanism. Lubricant is free to escape. Consequently, frequent maintenance operations have been needed to clean and lubricate the mechanism and thereby avoid premature wearing of the wrench. This is a time consuming inconvenience.  
         [0006]     The mechanism at the head end of a powered ratchet wrench should be compact in order to permit entry of the end of the wrench into constricted spaces. This complicates efforts to provide mechanism which is not subject to the problem discussed above.  
         [0007]     The present invention is directed to overcoming one or more of the problems discussed above.  
       BRIEF SUMMARY OF THE INVENTION  
       [0008]     In one aspect the present invention provides a motor driven ratchet wrench having a head end housing attached to a handle and a ratchet gear situated at a first opening in the housing. The wrench further including output means for applying torque to external threaded fasteners in response to rotation of the ratchet gear, a crankshaft extending through a second opening in the housing and pawl and pawl driver means in the housing for rotating the ratchet gear in repetitive increments in response to continuous rotation of the crankshaft. A plurality of seals includes seals disposed at each opening in the housing thereby blocking entry of external substances into the housing and thereby retaining lubricant in the housing.  
         [0009]     The invention provides a powered ratchet wrench in which moving parts at the head end of the wrench are situated in a sealed housing. This prevents entry of dirt or other materials and assures retention of lubricant. Wearing of components of the wrench is greatly reduced without requiring frequent cleaning a lubrication of the tool. The invention provides pawl mechanism and pawl driver mechanism which can be contained in the sealed housing without requiring any unsealed openings in the housing.  
         [0010]     The invention, together with further objects and advantages thereof, may be further understood by reference to the following detailed description of the preferred embodiments and by reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0011]     In the accompanying drawings:  
         [0012]      FIG. 1  is a perspective view of a motor driven ratchet wrench, embodying the invention, as viewed from the back of the tool.  
         [0013]      FIG. 2  is a perspective view of the head end portion of the wrench of  FIG. 1  shown disengaged from the other portions of the tool.  
         [0014]      FIG. 3  is a perspective view of the head end portion of the wrench of  FIG. 1  as viewed from the front of the tool.  
         [0015]      FIG. 4  is a broken out section view of the handle, motor and gear housing portion of the wrench of the preceding figures.  
         [0016]      FIG. 5  is a longitudinal section view of the head end portion of the wrench of the preceding figures.  
         [0017]      FIG. 6  is an exploded perspective view of the head end portion of the wrench of the preceding figures as viewed from the back of the tool.  
         [0018]      FIG. 7  is an exploded perspective view of a ratchet gear and gear driving mechanism which appears in assembled form in  FIG. 6 .  
         [0019]      FIG. 8  is an exploded perspective view of the head end portion of the wrench of the preceding figures and is similar to  FIG. 6  except that the apparatus is shown as viewed from the front of the tool.  
         [0020]      FIG. 9  is an exploded perspective view of the ratchet gear and gear driving mechanism of  FIG. 7  as viewed from the front of the tool.  
         [0021]      FIG. 10  is a perspective view of a portion of the head end of the ratchet wrench of the preceding figures in which a directional control is shown separated from the housing for purposes of illustration.  
         [0022]      FIG. 11  is an exploded perspective view of the directional control of  FIG. 10 .  
         [0023]      FIG. 12  is a diagrammatic view depicting the installation of the directional control of  FIG. 10  into the head end housing of the ratchet wrench.  
         [0024]      FIG. 13  is a broken out view of the back of the head end housing of the wrench of the preceding figures in which the directional control is shown prior to installation of the shift lever assembly in the head end housing.  
         [0025]      FIG. 14  shows the structure of  FIG. 13  with the directional control installed in the head end housing.  
         [0026]      FIG. 15  is a side view of a ratchet lever assembly component of the apparatus of the preceding figures.  
         [0027]      FIG. 16  is a view of the back face of the ratchet lever assembly of  FIG. 15   
         [0028]      FIG. 17  is an exploded perspective view of the ratchet lever assembly of  FIGS. 15 and 16 .  
         [0029]     FIGS.  18  to  21  are sectional views of the head end of the wrench of the preceding figures as viewed from the back of the wrench and depicting successive stages in the operation of the pawl and ratchet mechanism.  
         [0030]     FIGS.  22  to  25  are broken out views of the head end of the wrench of the preceding figures as viewed from the front of the wrench and depicting successive stages in the operation of the directional control mechanism.  
         [0031]      FIG. 26  is a longitudinal section view of the head end of a second embodiment of the invention which has a modified form of directional control for selecting the angular direction of the rotary force that is applied to threaded fasteners.  
         [0032]      FIG. 27  is an exploded perspective view of the directional control of  FIG. 26 .  
         [0033]      FIGS. 28, 29  and  30  are broken out front views of the apparatus of  FIG. 26  illustrating successive stages in the operation of the modified directional control.  
         [0034]      FIG. 31  is a perspective view of a ratchet gear and ratchet lever assembly of a third embodiment of the invention as viewed from the back of the assembly.  
         [0035]      FIG. 32  is an exploded perspective view of the ratchet gear and ratchet lever assembly of  FIG. 31 .  
         [0036]      FIG. 33  is a perspective view of the ratchet gear and ratchet lever assembly of  FIG. 31  as viewed from the front of the assembly.  
         [0037]      FIG. 34  is an exploded perspective view of the ratchet gear and ratchet lever assembly of  FIG. 33 .  
         [0038]      FIG. 35  is a frontal view of the ratchet gear and ratchet lever assembly of FIGS.  31  to  34 .  
         [0039]      FIG. 36  is a side view of the ratchet gear and ratchet lever assembly of  FIG. 35 .  
         [0040]      FIG. 37  is a broken out perspective view of ratchet lever and pawl components of the ratchet gear and ratchet lever assembly of FIGS.  31  to  36 .  
         [0041]      FIG. 38  is an exploded perspective view of a directional control component of the ratchet gear and ratchet lever assembly of FIGS.  31  to  36 .  
         [0042]      FIG. 39  is a longitudinal section view of the head end region of the third embodiment of the invention.  
         [0043]     FIGS.  40  to  44  are broken out views of the head end region of the third embodiment of the invention depicting successive stages in the operation of the apparatus.  
         [0044]      FIG. 45  is a front view of the ratchet lever assembly of a fourth embodiment of the invention.  
         [0045]      FIG. 46  is a side view of the ratchet lever assembly of  FIG. 45   
         [0046]      FIG. 47  is an exploded perspective view of the directional control component of the fourth embodiment.  
         [0047]     FIGS.  48  to  50  are broken out front views of the head end region of the fourth embodiment illustrating stages in the operation of the apparatus.  
         [0048]      FIG. 51  is a perspective view of the ratchet lever assembly of a fifth embodiment of the invention as viewed from behind the assembly.  
         [0049]      FIG. 52  is an exploded view of the apparatus of  FIG. 51 .  
         [0050]      FIG. 53  is a perspective view of the ratchet lever assembly of  FIGS. 51 and 52  as viewed from the front of the assembly.  
         [0051]      FIG. 54  is an exploded perspective view of the apparatus of  FIG. 53 .  
         [0052]      FIG. 55  is a front view of the ratchet lever assembly of FIGS.  51  to  53 .  
         [0053]      FIG. 56  is a side view of the ratchet lever assembly of FIGS.  51  to  55 .  
         [0054]      FIG. 57  is a broken out perspective view depicting components of the ratchet lever assembly of a fifth embodiment of the invention.  
         [0055]      FIG. 58  is an exploded perspective view of a directional control component of the fifth embodiment of the invention.  
         [0056]      FIG. 59  is a broken out front view of the head end region of the fifth embodiment of the invention.  
         [0057]      FIG. 60  is a broken out perspective view of the head end region of the fifth embodiment of the invention as viewed at the back of the apparatus.  
         [0058]      FIG. 61  is a section view of the head end region of the fifth embodiment of the invention taken along the central plane of the apparatus.  
         [0059]     FIGS.  62  to  65  are broken out front views of the head end region of the fifth embodiment of the invention illustrating successive stages in the operation of the mechanism.  
         [0060]      FIG. 66  is a broken out perspective view of components of a sixth embodiment of the invention which has a modified form of directional control for selecting the angular direction of the rotary force that is applied to threaded fasteners.  
         [0061]      FIG. 67  is an exploded perspective view of a shift lever assembly of the sixth embodiment of the invention.  
         [0062]      FIG. 68  is a longitudinal section view of the head end of the sixth embodiment of the invention.  
         [0063]     FIGS.  69  to  72  are broken out front views of the head end region of the sixth embodiment illustrating successive stages in the operation of the apparatus.  
         [0064]      FIG. 73  is a perspective view of a another embodiment of the invention having a head end assembly which is interchangeable with differing head end assemblies and which can operate with different forms of electrical power supply.  
         [0065]      FIG. 74  is a perspective view of the embodiment of  FIG. 73  showing the interchangeable head end assembly removed from the tool and showing an alternate form of connection to an electrical power supply.  
         [0066]      FIG. 75  is a perspective view of the interchangeable head end assembly of  FIGS. 73 and 74  as viewed from the front of the assembly.  
         [0067]      FIG. 76  is a broken out side view of a central portion of the tool of FIGS.  73  to  75 .  
         [0068]      FIG. 77  is a longitudinal section view of the interchangeable head end assembly of the tool depicted in FIGS.  73  to  76 .  
         [0069]      FIG. 78  is a longitudinal section view of another interchangeable head end assembly for the tool depicted in FIGS.  73  to  76  which head end assembly has an angled configuration.  
         [0070]      FIG. 79  is an exploded perspective view of still another interchangeable head end assembly for the tool depicted in FIGS.  73  to  76  which head end assembly an output member of the box end socket type.  
         [0071]      FIG. 80  is an exploded perspective view of a component of the interchangeable head end assembly of  FIG. 79  which includes a box end socket, ratchet gear, pawl and pawl operating mechanism.  
         [0072]      FIG. 81  is an exploded perspective view of the interchangeable head end assembly of  FIGS. 79 and 80  as viewed from the back of the assembly.  
         [0073]      FIG. 82  is an exploded perspective view of a directional control component of the interchangeable head end assembly of  FIGS. 79, 80  and  81 .  
         [0074]      FIG. 83  is a top view of a component of the interchangeable head end assembly of FIGS.  79  to  82  which includes a ratchet gear, pawl and pawl operating mechanism.  
         [0075]      FIGS. 84 and 85  illustrate successive stages in the operation of the interchangeable head end assembly of FIGS.  79  to  83 .  
         [0076]      FIG. 86  is a perspective view of a modified ratchet lever component for the previously described embodiments in which the component has a two piece construction.  
         [0077]      FIG. 87  is an exploded perspective view of the modified component of  FIG. 86 .  
         [0078]      FIG. 88  is an exploded perspective view of an alternate construction for a ratchet gear and output member assembly for the previously described embodiments.  
         [0079]      FIG. 89  is a perspective view showing the structure of  FIG. 88  in assembled form.  
         [0080]      FIG. 90  is a perspective view of an alternate construction for a head end housing component of the previously described embodiments in which the housing has a three piece construction, the apparatus being viewed from the back of the housing.  
         [0081]      FIG. 91  is a perspective view of the head end housing of  FIG. 90  as viewed from the front of the housing.  
         [0082]      FIG. 92  is an exploded perspective view of the head end housing of  FIGS. 90 and 91 .  
         [0083]      FIG. 93  is a longitudinal section view of the apparatus of  FIG. 90 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0084]     Referring initially to FIGS.  1  to  3  of the drawings, externally visible features of the motor driven ratchet wrench  11  of this example of the invention include a sealed head end housing  12  which is attached to a handle  13  through a gearing housing  14  and a motor housing  16 . In this example, the means  17  for applying torque to threaded fasteners which are to be loosened or tightened is a square drive of the known form which is of square cross section at its outer end and on which standardized sockets of known form and differing sizes can be snap engaged. An on/off control  19  is situated on the underside of handle  13 . Control  19  is a manually operable electrical switch as the wrench  11  of this example has an electrical drive motor. Alternately, the wrench  11  may have a pneumatic drive motor in which case control  19  is a manually operable valve. A flexible electrical cord  21  extends from the end of handle  13  for connection to a source of electrical power. Alternately, a battery for powering the wrench  11  can be contained within handle  13 . Cord  21  is replaced with a flexible air conduit if the wrench  11  is powered by a pneumatic motor.  
         [0085]     A directional control  22  provides a manually operable means which enables the operator to select the angular direction of the force which the wrench  11  applies to a threaded fastener. Prior ratchet wrenches in which the directional control is attached to moving internal parts of the ratchet mechanism require an opening in the head end housing that is larger than the control itself in order to accommodate to the motion of the directional control. Sealing of the head end of the wrench  11  is facilitated in the present invention as the shift lever assembly  22  is seated in a conforming opening  23  the head end housing  12  rather than being carried by a moving part of mechanism which is within the housing. Thus the opening  23  need not be larger than diameter of the assembly  22  itself and can be provided with a seal as will hereinafter be described. Other aspects of the directional control  22  will also hereinafter be described.  
         [0086]     Referring jointly to  FIGS. 4 and 5 , drive motor  24  is disposed within motor housing  16  which may be an integral cylindrical extension of handle  13 . The front end of motor housing  16  is closed by a stepped annular coupler member  26  which is in threaded engagement with the motor housing. Gear housing  14  is a sleeve having a threaded back end engaged with the coupler member  26  and a threaded forward end which is engaged with a threaded connector portion  27  of the head end housing  12  of the wrench  11 .  
         [0087]     Bearings  28  and  29 , seated in motor housing  16  and coupler member  26 , journal the rotor shaft  31  of motor  24 . Shaft  31  extends forward to deliver rotary drive to planetary gearing  32  situated in gear housing  14 . Planetary gearing  32  functions in the known manner to effect a speed reduction accompanied by an amplification of torque force. A rotary crankshaft  33  extends forward from gearing  32  to transmit drive to mechanism in head end housing  12  which will hereinafter be described. An annular seal  34 , seated in coupler member  26 , encircles rotor shaft  31 . Seal  34  prevents loss of lubricant from the planetary gearing  32 .  
         [0088]     The internal constructions of the motor  24  and planetary gearing  32  may be of the conventional designs well understood by those skilled in the art.  
         [0089]     Referring to  FIGS. 5, 6  and  7 , head end housing  12  forms a sealed chamber  36  defined by a back wall  37 , sidewall  38  which is of semicircular shape at the forward end and a cover plate  39 . Cover plate  39  seats on a rear shelf  41  at the back of chamber  36  and two side shelves  42  at opposite sides of the chamber. Shelves  41  and  42  may be integrally formed portions of the head end housing  12 . Threaded bolts  43  engage in bores in shelves  41  and  42  to secure the cover plate  39  in place. Entry of foreign material into chamber  36  and loss of lubricant at the perimeter of cover plate  39  is prevented by another seal  44  which extends around the periphery of the cover plate and which is seated in a peripheral groove  46  in the side of the cover plate.  
         [0090]     Referring to  FIGS. 6, 7 ,  8  and  9 , a ratchet lever  47  is disposed in chamber  36  and contains a ratchet gear  48 . Square drive member  18  is seated in ratchet gear  48  in centered relationship therewith and extends out of the head end housing  27  through a circular opening  49  in cover plate  39 . An annular seal  51  encircles a circular shank  52  portion of square drive member  18 , within opening  49 , to prevent entry of foreign material and to retain lubricant in chamber  36 .  
         [0091]     The previously described crankshaft  33  extends into chamber  36  through an axially directed bore  53  in the connector portion  27  of the head end housing  12 . Referring again to  FIGS. 4 and 5 , another annular seal  54  is seated in connector portion  27  of the housing  12  and encircles the crankshaft  33  to isolate lubricant in chamber  36  from the lubricant in planetary gearing  32  in instances where different lubricants are present. For example, the planetary gearing  32  may contain oil while components in chamber  36  are lubricated with grease. The passage leading to chamber  36  which extends along motor shaft  31  and crankshaft  33  is also sealed by the previously described seal  34 . Thus seal  54  is not needed in instances where the same lubricant is used in the planetary gearing  32  and in chamber  36 .  
         [0092]     Referring to  FIGS. 3, 10  and  11 , directional control  22  has a cylindrical cap  56  which is seated in the opening  23  at the front face of head end housing  12 . A circular seal  57  is seated in a groove  58  that extends around the periphery of cap  56  thereby sealing chamber  36  at opening  23 .  
         [0093]     The above described seals  44 ,  51 ,  54  and  57  collectively seal all opening in the walls of the chamber  36  of the head end housing  12 . Ratchet lever  47  has a configuration which enables the lever and associated moving components to be wholly enclosed in the sealed chamber  36 .  
         [0094]     In this example, with reference to  FIGS. 6, 7 ,  15 ,  16  and  17 , the head end of the ratchet lever  47  has spaced apart coaxial ring portions  59  which are centered on the rotary axis of square drive  18  with the ratchet gear  48  being disposed between the ring portions in coaxial relationship with the ring portions. The circular curvature of the adjacent sidewall  38  of head end housing  12  and a similar curvature of the adjacent walls of shelves  42  prevent movement of the ring portions  59  other than rotational movement. Square drive  18  extends through the central openings  61  of the ring portions  59  and out of chamber  36  through the previously described opening  49  and seal  51 . External splines  62  on square drive  18  engage internal splines  63  of ratchet gear  48  to cause the square drive to rotate with the gear.  
         [0095]     An arm  64  of the ratchet lever  47  extends from the ring portions  59  towards crankshaft  33 . Referring to  FIGS. 5, 6  and  7 , a coupler cylinder  66  is situated in a conforming cylindrical cavity  67  in the end of arm  64 . A crankpin  68  at the end of crankshaft  33  extends into an opening  69  in the coupler cylinder  66 . Crankpin  68  extends in parallel relationship with the rotary axis of crankshaft  33  but is offset from that axis. Consequently, the motor driven rotation of the crankshaft  33  causes a repetitive limited angular oscillation or pivoting movement of the ratchet lever  47  about the axis of ratchet gear  48 .  
         [0096]     Referring to  FIGS. 5, 15 ,  16  and  17 , a slidable pawl  71  is carried by the ratchet lever  47  and causes repetitive turning of the ratchet gear  48  in a single direction in response to the angular oscillation of the ratchet lever  47 . Pawl  71  is disposed in a compartment  72  in the ratchet lever  47  which extends towards ratchet gear  48 . Pawl  71  has gear teeth  73  which intermittently engage the teeth of the ratchet gear  48  as will hereinafter be further described. A pin  74  extends from the pawl into a right angled guide slot  76  in the adjacent walls of compartment  72 . Referring again to  FIG. 8 , pawl biasing springs  75  in the directional control  22  exert spring forces on pin  74  which urge the pin towards one end of slot  76  when the control is set too cause clockwise rotation of the ratchet gear  48  and which urge the pin towards the opposite end of slot when the control is set to cause counter-clockwise rotation. The directional control  22  including pawl biasing springs  75  will hereinafter be further described.  
         [0097]     Operation of the pawl  71  and further structural detail of the mechanism will best be understood by reference to FIGS.  18  to  21  which show successive stages in a power stroke and a return stroke of ratchet lever  47 . At the beginning of the power stroke depicted in  FIG. 18 , pawl  71  is being urged to the position shown in the figure by the pawl biasing springs  75 . At this position the pawl  71  is forced into engagement with ratchet gear  48  as it is wedged between the gear and an adjacent obliquely angled wall  77  of compartment  72 . Thus the following pivoting motion of ratchet lever  47  forces ratchet gear  48  to rotate an incremental amount. At the end of the power stroke as shown in  FIG. 19 , lateral travel of crankpin  68  reverses and the ratchet lever  47  begins to pivot in an opposite direction. This allows pawl  71  to retract from the ratchet gear  48  as shown in  FIG. 20  as it the reversed motion of the oblique wall  77  does not act to wedge the pawl against the gear. Any drag force which the pawl  71  might exert on gear  48  at this stage is resisted by detent rods  78  which are urged against the teeth of the gear by coil springs  79 . At the end of the return stroke as shown in  FIG. 21 , pivoting movement of ratchet lever  47  reverses again causing reengagement of pawl  71  with gear  48  and a repetition of the cycle of operation described above. Consequently, gear  48  and thus square drive  18  is rotated in a single angular direction in a continuing series of intermittent movements.  
         [0098]     If the operator shifts the directional control to the alternate setting, biasing spring force urges pin  74  and thus pawl  71  towards the opposite end of angled guide slot  76 . Operation then proceeds essentially as described above except that the pattern of pawl  71  movement is reversed and ratchet gear  48  and square drive  18  are turned in an opposite rotational direction.  
         [0099]     The directional control  22  at different stages of operation is depicted in FIGS.  22  to  25 . Cap  56  of the directional control has a radial extending lever  81 , situated outside of head end housing  12 , which the operator may turn to the orientation shown in  FIGS. 22 and 23  in order to select rotation of the square drive  18  in a first angular direction. Turning of lever  81  to the orientation shown in  FIGS. 24 and 25  reverses the angular motion of square drive  18 . Protrusions  82  on the outside surface of head end housing  12  demark the range of turning of lever  81  between the two positions described above. Referring to  FIGS. 22 and 11  in conjunction, the pawl biasing springs  75  are angled wire springs attached to pedestal supports  83  within cap  56 . Each spring  75  is positioned to urge pawl pin  74  in an opposite direction. A first of the springs  75  acts on the pawl pin  74  when lever  81  of the directional control is oriented as shown in  FIGS. 22 and 23 . This positions the pawl  71  at one side of guide slot  76  as has been described with reference to FIGS.  18  to  21 . The other spring  75  acts on the pawl pin  74  when lever  81  is turned to its other position as shown in  FIGS. 24 and 25 . This positions the pawl  71  at the other side of guide slot  76  to reverse the rotation of square drive  18  in the manner previously described. Stops  85  in caps  56  are positioned to prevent both springs  75  from acting on pawl pin  74  at the same time.  
         [0100]     Referring jointly to  FIGS. 10, 12  and  14 , an arcuate lip  84  extends outward from the base of cap  56  of directional control  22  at the portion of the cap that is opposite from lever  81 . Lip  84  fits into a conforming arcuate groove  86  which partially encircles opening  49  at the base of the opening in order to retain directional control  22  in place. Groove  86  is longer than lip  84  by an amount sufficient to enable the above described turning of cap  56  between the two settings of the control. As shown in  FIG. 10 , the directional control  22  assembly can be fitted into place at opening  49  by tilting the control as it is being inserted into the opening.  
         [0101]     As has been described with reference to FIGS.  22  to  25 , the direction in which the ratchet gear  48  is turned depends on the direction of the spring force which is applied to the pawl pin  74 . Manual pivoting of the directional control  22  reverses this spring force. FIGS.  26  to  30  depict a second embodiment of the directional control  22   a  which has a different internal construction but accomplishes the same result of applying a selectively reversible spring force to pawl pin  74 .  
         [0102]     Referring to  FIGS. 26 and 27 , directional control  22   a  has a cylindrical cap  56   a  encircled by an annular seal  57   a  and having a radially directed lever  81   a  and a retainer lip  84   a  which are similar to the previously described portions of the first embodiment. Cap  56   a  contains a rectangular plunger  87  which is slidable in a rectangular slot  88  formed in the cap. One end of a compression spring  89  urges plunger  87  against pawl pin  74  and the other end of the spring acts against a detent ball  91 . Plunger  87  and slot  88  are oriented to cause the spring force to urge pawl pin  74  towards one end of the angled pin guide slot  76  when lever  81   a  is turned to the first setting shown in  FIG. 28 . The spring  89  is compressed, as shown in  FIG. 29 , while lever  81   a  is being moved away from the first setting as pawl pin  74  can only move along the guide slot  76 . When lever  81   a  reaches its second setting as shown  FIG. 30  the spring  89  is able to extend and urge the pawl pin  74  towards the other end of the angled guide slot  76  thereby reversing the rotational direction of the ratchet gear in the manner previously described. Spring  89  urges detent ball  91  into a pocket  92  in the wall of opening  49  when the lever  81   a  is at either of its two settings to create a force which tends to resist movement of the lever away from the selected setting.  
         [0103]     The pawl  71  of the previously described embodiments of the invention may be described as a sliding bi-directional pawl as it is shifted in a lateral direction to reverse the rotation of the output of the wrench. FIGS.  31  to  34  depict a third embodiment of the invention having what may be termed a pivoting bi-directional pawl  71   b.  Referring initially to FIGS.  31  to  34  in particular, the ratchet lever  47   b  is similar to the corresponding component of the previously described embodiments except that it has a circular chamber  93  in which the pawl  71   b  is disposed. Ratchet gear  48  and square drive  18  are similar to the corresponding components of the previously described embodiments. Directional control; has a modified configuration which will hereinafter be described.  
         [0104]     Referring jointly to FIGS.  35  to  39 , pawl  71   b  is cylindrical and conforms in shape with chamber  93  except that two spaced apart bands of gear teeth  96  extends along the portion of the surface of the pawl that faces ratchet gear  48 . The pawl  71   b  may be rotated within chamber  93  to bring either band of gear teeth  96  into position for engaging the ratchet gear  48 . A compression spring  97  is disposed in a radial bore  98  in pawl  71   b  and acts against a detent ball  99  situated at the outer end of the bore. Bore  98 , spring  97  and ball  99  are positioned to enable travel of the ball along a detent guide slot  101  which is recessed in the wall of chamber  93 . Slot  101  limits rotation of pawl  71   b  to an orientation at which a first of the bands of gear teeth  96  is positioned to engage ratchet gear  48  and a second orientation at which the other of the bands of gear teeth is positioned to engage the gear  48 . A linear rib  102  extends across the front surface of pawl  71   b  to enable manual turning of the pawl as will hereinafter be further described.  
         [0105]     The directional control  22   b  of this embodiment has a modified cylindrical cap  56   b  with a radial extending lever  81   b  and, together with an annular seal  57   b,  is seated in opening  49  of the head end housing in the same manner as the corresponding component of the previously described embodiments. Another compression spring  103  and detent ball  104  are seated in a radial bore  106  in cap  56   b.  A linear channel  107  extends diagonally across the inner face of cap  56   b  along the rib  102  of pawl  71   b.  Channel  107  is broader than rib  102  to enable limited rotation of pawl  71   b  without interference from the cap.  
         [0106]      FIG. 40  depicts the above described components of the third embodiment at the start of a power stroke. One of the sets of pawl teeth  96  engages the ratchet gear  48  and turns the gear as the ratchet lever  47   b  is pivoted by turning of crankshaft  33  in the previously described manner. Detent  99  is situated at one end of slot  101  and prevents rotation of the pawl  71   b  relative to chamber  93  at that stage.  FIG. 41  depicts the components at the end of the power stroke at which time the ratchet lever  47   b  begins its opposite pivoting movement or return stroke.  FIG. 42  depicts the components during the return stroke of the lever  47   b.  Pawl  71   b  can rotate out of engagement with ratchet gear  48  at this stage as detent  99  can travel along slot  101  to accommodate to the pawl rotation. The detents  78  which act against the ratchet gear  48  inhibit any turning of the ratchet gear  48  at this stage. Thus repeated oscillation of lever  47   b  causes a repetitive incremental turning of ratchet gear  48  in s single direction  
         [0107]      FIG. 43  depicts the position of the directional control  22   b  during the power stroke described above. At the beginning of the power stroke, the bar  102  of pawl  71   b  is aligned with the channel  107  of the directional control  22   b.  Channel  107  is sufficiently broad that it does not interfere with the small pivoting movements of bar  102  that are required during the power strokes and return strokes.  FIG. 44  depicts the structure of  FIG. 43  at a time when the operator is manually pivoting lever  81   b  to change the direction of rotation of the output of the wrench. The walls of channel  107  force turning of the pawl bar  102  and thus the pawl  71   b  to travel the pawl detent ball  99  towards the opposite end of slot  101 . The initial part of this travel causes compression of pawl detent spring  97 . Force exerted by the compressed spring  97  then aids in turning the pawl  71   b  during the final part of this travel. The turning of the pawl  71   b  causes the other set of pawl teeth  96  to engage the ratchet gear  48 . Operation then proceeds as described above except that the ratchet gear is turned in an opposite direction.  
         [0108]     The third embodiment described above with reference to FIGS.  31  to  34  has a cylindrical pivoting pawl  71   b  with a spring  97  and detent ball  99  that urge the pawl towards a selected one of two alternate angular positions in order to determine the direction of rotation of the ratchet gear  48 . The spring force may be applied to the pawl in a different manner as in the fourth embodiment of the invention shown in FIGS.  45  to  50 . Referring initially to  FIGS. 45 and 46 , the cylindrical pivoting pawl  71   c  may be similar to the pawl of the third embodiment except that it has no diagonally directed bar and instead has a pin  108  which protrudes out of the ratchet lever chamber  93  that contains the pawl. As in the third embodiment, pawl  71   c  has two spaced apart sets of teeth  96  and the pawl is turnable between two different angular orientations at each of which a different one of the sets of teeth is positioned to engage the ratchet gear  48  during the power strokes of the ratchet lever  47   c.    
         [0109]     Referring to  FIG. 47 , the directional control  22   c  of the fourth embodiment has a circular cap  56   c  seating an annular seal  57   c  and having a radially extending shift lever  81   c  and a retainer lip  84   c  which are similar to the corresponding components of the previously described embodiment. A plunger  109  is slidable along a rectangular guide slot  110  which extends diagonally within cap  56   c  at the underside of the cap  56   c.  A compression spring  111  extends from a detent ball  112  at the periphery of cap  56   c  into a bore  113  in plunger  109 .  
         [0110]     Referring jointly to  FIGS. 48, 49  and  50 , cap  56   c  seats in the previously described manner in the circular opening  49  in the sealed head end housing  12  and is manually turnable to either of two different angular orientations to select the direction of rotation of the ratchet gear. Pockets  114  in the wall of opening  49  seat the detent ball  112  at each of these two orientations of the cap  56   c.  At either orientation, spring  111  pressure causes plunger  109  to exert a force against pawl pin  108  which rotates the pawl to bring one of the two sets of pawl teeth  96  into position for engaging ratchet gear  48  during power strokes of the ratchet lever in the manner previously described with reference to the third embodiment of the invention. During manual turning of the directional control  22   c,  as shown in  FIG. 50  in particular, spring  111  compresses to allow travel of detent ball  112  from one of the pockets  114  to the other.  
         [0111]     FIGS.  51  to  65  depict a fifth embodiment of the invention which is basically of the pivoting pawl type described above with reference to the third and fourth embodiment while having a modified directional control  22   d  and a modified form of pawl pin  116  for applying spring pressure to the pawl in a selected one of two different directions in order to rotate the ratchet gear  48  in a selected direction. Referring to FIGS.  51  to  54  in particular, ratchet lever  47   d  has a modified internal configuration, which will be hereinafter described, to accommodate to the differing pawl pin  116 . Ratchet gear  48 , square drive  18  and other components may be similar to those previously described.  
         [0112]     The pawl pin  116  has front and back cylindrical bearing surfaces  117  and  118  respectively separated by a center section  119  of square cross section which extends through a conforming square opening  221  in pawl  71   d.  Opposite arms of an angled bar  222  extend laterally from the front end of pawl  71   d  to receive spring pressure as will hereinafter be described.  
         [0113]     Referring to  FIGS. 55, 56  and  57  in conjunction, bearing surfaces  117  and  118  of pawl pin  116  seat in conforming openings  223  and  224  in ratchet lever  47   d.  This positions the angled bar  222  of pawl pin  116  adjacent to the front surface of ratchet lever  47   d  and positions pawl  71   d  for engaging and disengaging ratchet gear  48  in the previously described manner as ratchet lever  47   d  is oscillated.  
         [0114]     Referring jointly to FIGS.  58  to  61 , the directional control  22   d  of the fifth embodiment has an arm  226  which extends radially from the cylindrical cap  56   d.  A bore  227  extends diagonally through cap  56   d  including arm  226 . A slidable rod  228  is disposed in the bore and extends out of arm  226 . A compression spring  229  in bore  227  urges rod  228  towards arm  226  and reacts against a detent ball  231  situated at the end of the bore that is opposite from arm  226 .  
         [0115]     Directional control  22   d  and an annular seal  57   d  are fitted into a conforming opening  49   d  in the front wall of head end housing  12  in the previously described manner. Arm  226  and rod  228  fit into a recess  232 , formed in the inside surface of the front wall of the housing  12 , which enables the rod to bear against the previously described angled bar  222  of pawl pin  116 . One of two spaced apart pockets  233  in the wall of opening  49   d  seats detent ball  23  when directional control  22   d  is turned to either of its two settings. This resists turning of the directional control  22   d  by reactive forces produced by the pawl mechanism  
         [0116]     FIGS.  62  to  65  show the pawl and ratchet and directional control components of the fifth embodiment at successive stages of operation.  FIG. 62  depicts the components at the beginning of a power stroke with directional control  22   d  turned to the setting which causes counterclockwise rotation of ratchet gear  48  and square drive  18 . A first set of the pawl teeth  96  engages ratchet gear  48  during the power stroke to cause an increment of rotation of the gear as ratchet lever  47  is pivoted in the previously described manner. The contour of the opening  93   d  in which pawl  71   d  is situated keeps the pawl from turning out of engagement with gear  48  at this time.  FIG. 63  depicts the same mechanism at the end of the power stroke. Rod  228  and spring  229  continue to apply pressure to bar  222  of the pawl pin  116  at this time but the contour of opening  93   d  allows pawl  71   d  to turn out of engagement with ratchet gear  48  during the subsequent return movement of ratchet lever  47   d  as shown in  FIG. 64 .  FIG. 65  depicts the mechanism after the operator has turned directional control  22   d  to its alternate setting. Pressure from rod  228  and spring  229  now acts to bring the other set of pawl teeth  96  into position for engagement with the ratchet gear  48 . Continued oscillation of the ratchet lever  47   d  then turns ratchet gear  48  in an opposite direction.  
         [0117]     FIGS.  66  to  72  depict a sixth embodiment of the invention having a pivoting pawl  71   e  that is compatible with the sealed head end housing  12 . The sixth embodiment may be similar to the fifth embodiment as described above except that the pawl  71   e,  pawl pin  116   e  and ratchet lever  47   e  have modified configurations. In particular pawl  71   e  has a recess  234  which extends into the region of the pawl that is opposite from the two sets of pawl teeth  96 . The bar  222   e  which extends across the top of pawl pin  116   e  is straight instead of being angled as in the previous instance. A compression spring  236  and a detent ball  237  are disposed in a bore  238  in ratchet lever  47   e  that extends away from the center of the back wall of the pawl chamber  238  of the lever.  
         [0118]     The directional control  22   e  of the sixth embodiment is of the previously described form having a linear channel  107   e  which extends diagonally across the underside of the cap  56   e.    
         [0119]     Referring to  FIG. 69  and  70 , the pawl recess  234  has two pockets  241 , one of which seats detent ball  237  when pawl  71   e  is turned to produce counter-clockwise rotation of ratchet gear  48  and the other of which seats the ball when the pawl is pivoted to its alternate setting. Under either condition, spring  236  and ball  237  exert pressure on the pawl  71   e  which urges the pawl towards engagement with the ratchet gear  48 .  
         [0120]      FIG. 69  depicts the mechanism at the beginning of a power stroke of ratchet lever  47   e.  The adjacent back wall  242  of pawl chamber  238  forces pawl  71   e  to turn with the lever  47   e  and thereby turn the ratchet gear  48 . As shown in  FIG. 70 , pawl  71   e  is free to turn slightly in a reverse direction, to disengage from gear  48 , during the return stroke of the lever  47   e.    
         [0121]      FIG. 71  depicts directional control  22   e  during the mode of operation described above. Channel  107   e  of the directional control  22   e  is sufficiently broad that it does not interfere with the small oscillation of pawl pin bar  222   e  that occurs as the ratchet lever  47   e  oscillates. When the operator turns the directional control  22   e  to its alternate setting, as shown in  FIG. 72 , the walls of channel  107   e  force turning of bar  222   e.  This shifts the pawl to its alternate position and reverses the rotation of ratchet gear  48 .  
         [0122]     Referring to FIGS.  73  to  75 , the wrench  11   f  may be designed to enable interchanging of one type of head end assembly  243  with a head end assembly of a different type. For example, the previously described head end assemblies have output elements of the square drive form on which separate sockets can be fitted. Replaceable head end assembly  243  of this example is of the box end type which has an output element  18   f  that is formed as a socket for directly engaging a threaded fastener. Except as hereinafter described, the pawl and other internal components of the replaceable head end assembly  243  and the directional control  22   f  of head end assembly  243  may be of any of the previously described forms.  
         [0123]     To enable interchanging, the replaceable head assemblies  243  have an adapter  244  of square cross section which is fitted into a conforming hollow receiver  246  that extends forward from the planetary gear housing  14   f  of the tool. Crankshaft  33   f  is elongated in order to extend through the nested adapter  244  and receiver  246  and to engage the planetary gearing in the previously described manner. Referring jointly to  FIGS. 76 and 77 , the nested adapter  244  and receiver  246  are latched together by a spring loaded plunger  247  which protrudes from a side of adapter  244 . Plunger  247  can be depressed in order to insert the adapter  244  into receiver  246  and then snaps outward into an aperture  248  in the sidewall of the receiver when the adapter and receiver are fully nested. The plunger  247  can be depressed again in order to separate the adapter  244  and receiver  246  when a particular head assembly  243  is to be replaced with another.  
         [0124]     Referring to  FIG. 78 , a replaceable head assembly  243   g  can be angled to enable operation in confined spaces where threaded fasteners may not be accessible with a straight head assembly. For this purpose, the adapter  244   g  can be angled relative to the head end housing  12   g  and the components within the housing without interfering with operation of the components in the previously described manner.  
         [0125]     Referring to  FIG. 74, 76  and  FIG. 78  in conjunction, versatility of the angled head end assembly  243   g  can be enhanced by providing plunger engaging apertures  248  in more than one wall of the adapter receiver  246 . In this example each of the four walls of the receiver  246  has an aperture  248  for seating the plunger  247  of the adapter  244 . The head end assembly  243   g  can then extend from the handle at any selected one of four different angles depending on which is appropriate for a particular work site.  
         [0126]     Referring to  FIGS. 73 and 74  in particular, the powered ratchet wrench  11   f  of this example has a receptacle  249  at the end of the handle  13  that is shaped to receive and seat a battery  250  as shown in  FIG. 73 . Alternately, as shown in  FIG. 74 , the battery may be replaced with an electrical cord  21   f  having a plug  251  shaped to seat in receptacle  249 . Cord  21   f  may connect with any suitable external power source. In this example the end of cord  21   f  has an adapter  252  of the known kind that can be plugged into the cigarette lighter socket of an automobile. In either case, spring clips  253  on the plug or battery snap engage in slots  254  in the wall of receptacle  249 . Contacts  256  in the receptacle provide for electrical connection of switch  19   f  to the power source.  
         [0127]      FIGS. 79, 80  and  81  illustrate a suitable internal construction for a head end assembly  243  in which the output member is a box end socket  256  of the type discussed above. The cylindrical box end socket  256  is seated in the head end of the ratchet lever  47   h  in coaxial relationship with ratchet gear  48   h  and has external splines  257  which engage internal splines  258  of the ratchet gear. The central portion of socket  256  at which the external splines  257  are located is a band of greater diameter than the end regions of the socket thereby enabling retention of the socket between the previously described ring portions  59  of the ratchet lever. The pawl driving mechanism within head end assembly  243  may be similar to the corresponding components of any of the previously described embodiments of the invention.  
         [0128]     As the head end assembly  243  of this example is of the replaceable type, it is provided with an adapter  244  of the previously described form which includes a laterally protruding spring loaded plunger  247  for engaging the adapter with the other components of the tool as previously described. As best seen in  FIG. 81  in particular, ratchet lever  47  and box end socket  256  are retained in place by a cover plate  39  which seats against shelves  41  and  42  in the head end housing  12  in the previously described manner. The housing  12  contains seals  44 ,  51 ,  54  and  57  at the previously described locations to prevent entry of foreign material and to retain lubricant. The front surface of head end housing  12  of this example differs from the housings of the previously described embodiments in that it has an additional circular opening  259  into which the box end socket  256  extends in order to expose the socket at both the front and the back of the tool. Another circular seal  261  is seated in opening  259 .  
         [0129]     This particular example of the invention has a pawl of the type previously described with reference to the third embodiment of the invention as shown in FIGS.  31  to  34 . Thus the pawl  71   b  has a diagonally extending bar  102  which is selectively turned between two angular orientations in order to select the direction of rotation of the output member of the wrench. Referring again to FIGS.  79  to  81 , the directional control  22   h  of this example which enables manual turning of the bar  102  from outside of the sealed head end housing  12  has a construction that differs from the corresponding component of the third embodiment.  
         [0130]     In particular, with reference to FIGS.  82  to  85  in conjunction, the cylindrical cap  56   h  of directional control  22   h  is similar to that of the previously described embodiment except that it has a pin  262  which protrudes from the underside of the cap to interact with the bar  102  of pawl  71   b.  As in the previous instance, cap  56   h  is encircled by a seal  57 , has a radially extending lever  81  for facilitating manual turning of the cap and a compression spring  103  and detent ball  104  are disposed in a radial bore  106  in the cap. Pockets  92 , shown in  FIGS. 84 and 85 , seat the detent ball  104  when the cap  56   h  is turned to either of its angular orientations. Turning of the cap  56   h  from one of these orientations to the other causes pin  262  to turn bar  102  sufficiently to reverse the direction of rotation of the ratchet gear  48   h  in the previously described manner.  
         [0131]     Specific examples of ratchet gear driving mechanism have been described above that can be contained in a sealed head end housing. It should be recognized that variations of the design of various components are possible. For example,  FIGS. 86 and 87  depict an alternate construction in which the ratchet gear  48   j  and the square drive  18   j  are a single integral output element  263 . In order to assemble the integral output element  263  into the ratchet lever  47   j,  the ratchet lever is formed as a two piece component. The back portion  264  of the ratchet lever  47   j  which is situated behind the ratchet gear  48   j  is a removable plate that is secured to the front portion  266  of the ratchet gear by screws  267 . The removable back portion  264  does not include the wall  268  of the cavity  67   j  in which coupler cylinder  66   j  oscillates. Wall  268  remains integral with front portion  266  of the ratchet lever  47   j  to provide an uninterrupted bearing surface for the coupler cylinder  66   j.  The two piece ratchet lever  47   j  may otherwise be similar to the corresponding component of previously described embodiments of the invention.  
         [0132]      FIGS. 88 and 89  depict an alternate construction in which the ratchet gear  48   k  and square drive  18   k  are again separable components and are engaged with each other by a pair of pins  269  instead of by splines as in previously described embodiments. Pins  269  are disposed in bores  271  that are located to be partially in square drive  18   k  and patially in the ratchet gear  48   k.  Thus the pins  269  function as keys which force the ratchet gear  48   k  and square drive  18   k  to rotate together.  
         [0133]     FIGS.  90  to  93  depict an alternative construction for the sealed head end housing  12   m  in which the housing has three separable component layers held together by screws  272 . In particular, the portion of the housing which is behind the ratchet lever  47   m  is a separable back plate  273  and the portion of the housing which is in front of the lever is a separable front plate  274 . Plates  273  and  274  seat against a center layer  276  and seals  277  are situated between the back and front plates and the center layer. Components such as the ratchet lever  47   m,  ratchet gear  48   m,  pawl  71   m  and crankshaft  33   m  are contained within the center layer  276  and may be similar to the corresponding components of any the previously described embodiments of the invention such as, in this particular example, the embodiment of  FIG. 27  to  FIG. 30 .  
         [0134]     An advantage of the three piece sealed head end housing  12   m  of FIGS.  90  to  93  is that the center layer  276  may be formed of a material that differs from the material that the front and back plates  273  and  274  are formed of which is typically steel. Although not apparent in the drawing, dimensional tolerances can be selected so that the curved surfaces  278  of front and back plates  273  and  274  that contact square drive  18   m  function as the bearing surfaces for the square drive. The center layer  276  of the housing can then be formed of a lighter and less wear resistant material such as a high impact plastic.  
         [0135]     While the invention has been described with reference to certain particular embodiments for purposes of example, many other variations and modifications of the sealed powered ratchet wrench are possible and it is not intended to limit the scope of the invention except as defined by the following claims.