Abstract:
A flat headed, reversible power ratchet of relatively small size which uses integral bosses and apertures in its housing to locate and control the movement of its yoke and driving gears on bosses integral to the housing with the driving gear mounted in a bore within the yoke, which has its pawls and pawl controls within the yoke adjacent the gear, and by utilizing a pair of linkages which pivot about the yoke and about the housing in overlapping arcs to stabilize the position of the directional controls during operations.

Description:
This invention relates to pneumatically operated ratchet tools. 
   BACKGROUND 
   There is a need for a low profile, compact, power ratchet tool adapted for use in small areas where the conventionally sized ratchets cannot provide ready access. U.S. Pat. No. 6,282,990 was issued to me for such a ratchet. My present invention represents a substantial improvement over the former in that it is more compact, has higher reversing reliability, fewer parts, greater efficiency, and is provided with a positive latching reversing control. 
   It is the object of this invention to provide a low profile flat head ratchet which is more compact, has higher reversing reliability in that the reversing directional controls lock into place, and has greater efficiency, 

   
     IN THE DRAWINGS 
       FIG. 1  is a perspective view of a preferred embodiment of my invention; 
       FIG. 2  is a perspective view of the interior of the upper housing; 
       FIG. 3  is a perspective view of the interior of the lower housing 
       FIG. 4  is an enlarged sectional view taken along lines  4 — 4  of  FIG. 1 : 
       FIG. 5  is a fragmentary sectional view taken along lines  5 — 5  of  FIG. 4 : 
       FIG. 6  is a fragmentary sectional view taken along lines  6 — 6  of  FIG. 4 ; 
       FIG. 7  is an bottom perspective view of my reverser; 
       FIG. 8  is an top perspective view of my reverser link; 
       FIG. 9  is an exploded view of my invention; and 
       FIG. 10  is an enlarged view of my pawl chamber  340 . 
   

   DESCRIPTION 
   Referring now in more detail by reference character to the drawings, which illustrate a preferred embodiment of my invention, A designates a reversible power ratchet having an upper housing  100  comprising an elongated shell  102  having an enlarged end  104 , an elongated flat top  106 , and an annular wall  108  at its other end. The enlarged end  104  is provided with three concentric annular sections  110 ,  112 ,  114  extending inwardly from the end  108  to the center of the housing  100 , the section  110  being the largest in radius and the section  114  being the smallest in radius. Provided on the inner wall of the flat top  106  near the end  108  are two downwardly extending, concentric, annular bosses  116 ,  118 , the boss  118  being closer to the top  102  and being larger in radius than the boss  116 . It should be here noted that there is substantial separation between the boss  118  and the inner wall  120  defined by the end of the section  114  for purposes presently more fully to appear. Centrally located on the top  106  is a bore  122  and located on the outer portion of the top  106  are two upwardly projecting stops  124 ,  126 . 
   The lower housing  200  similarly comprises an elongated shell  202  which is provided with an enlarged end  204 , an elongated flat bottom  206 , and an annular wall  208  at its other end. The enlarged end  204  is provided with three concentric annular sections  210 ,  212 ,  214  extending inwardly from the end  208  to the center of the housing  200 , the section  210  being the largest in radius and the section  214  being the smallest in radius. Provided on the inner wall of the flat bottom  206  near the end  208  is an upwardly extending annular boss  216  provided with a concentric bore  218  which extends through the boss  216  and the bottom  206 . It should be here noted that there is also substantial separation between the boss  216  and the inner wall  220  defined by the end of the section  214  for purposes presently more fully to appear. Centrally located on the bottom  202  between the boss  216  and the wall  220  is an outwardly projecting clearance dimple  222 . 
   The two housings  100 ,  200 , are sized and shaped for engaged attachment to each other in such manner that
         (a) the sections  110 ,  210 , define a smooth cylindrical threaded means for attaching the tool A to a conventional pneumatic motor (not shown),   (b) the sections  114 ,  214 , define a cylindrical passageway for a bell crank C to be driven;   (c) the bosses  116 ,  118 ,  216 , and the bore  218  are all coaxial; and   (d) the walls  120 ,  220 , are in alignment and define a chamber D within the combined housings  100 ,  200 .       

   Referring in detail to  FIG. 9 , mounted in the combined housings  100 ,  200  in the space defined by the sections  114 ,  214 , is a bearing  300 , in which is rotatably disposed a bell crank  302  provided at its driven end  304  with a bell crank ball  306 . Disposed in the space between the bell crank ball  304  and the bosses  116 ,  118 ,  216 , in the combined housings  100 ,  200 , is a yoke  310  having a bore  312  sized for pivotal disposition about the boss  118 . 
   The end  314  of the yoke  310  away from the boss  118  is U-shaped and sized for accepting the bell crank ball  304  so that the yoke  310  will be pivoted back and forth about the boss  118  in the conventional manner as the bell crank  302  is rotatably driven. On opposing sides of the bore  312 , the yoke  302  is provided with a pair of complementary pawl chambers  320 ,  340  each respectively adapted to house a pawl  322 ,  342 . Immediately adjacent to and in communication with the pawl chamber  320  is a spring chamber  324  in which is disposed a U-shaped spring  326  having a flat face  328  which is seated in spring chamber  324  and a V-shaped other face  330  which presents an outwardly directed bias to the pawl  322 , urging the pawl  322  into the bore  312 . Similarly, immediately adjacent to and in communication with the pawl chamber  340  is a spring chamber  344  in which is disposed a U-shaped spring  346  having a flat face  348  which is seated in spring chamber  344  and a V-shaped other face  350  which projects into the pawl chamber  340 . 
   The pawl chamber  320  is slightly deeper in depth than the spring chamber  324  and is provided with a short wall section  332  where it intersects the spring chamber  324 . The pawl chamber  320  is also provided with an arcuate end  334 , the arc of which is substantially greater than 180 degrees, and at its other end opens into the bore  312 , all for purposes presently more fully to appear. Similarly, the pawl chamber  340  is slightly deeper in depth than the spring chamber  344  and is provided with a short wall section  352  where it intersects the spring chamber  344 . The spring chamber  340  is also provided with an arcuate end  354 , the arc of which is substantially greater than 180 degrees, and at its other end opens into the bore  312 , all for purposes presently more fully to appear. The spring chambers  324 ,  344 , and the pawl chambers  320 ,  340 , each extend downwardly from the top  360  of the yoke  312 . 
   Rotatably disposed in the bore  312  is a drive gear  400  provided at its end near the boss  118  with an axially extending annular recess  402  and at its other end with a square socket attachment post  404  which extends through the bore  218  for conventional attachment of sockets (not shown). Disposed between the end of the boss  118  and the base  406  of the recess  402  is a washer sandwich  408  comprising a wave washer  410  disposed between an upper friction washer  412  and a lower friction washer  414 . The drive gear  400  also includes a diametrically reduced intermediate segment  416  which is sized for close fitting but freely movable disposition in the bore  218 . It should be here noted that the gear  400  is provided with gear teeth constructed at angles which will enable efficient engagement with the pawls  322 ,  342 , (similar to the teeth on the gear described in U.S. Pat. No. 5,738,192 issued to me on Apr. 14, 1998 for Power Tool Drives), and similarly the teeth on each of my pawls  322 ,  342 , are constructed of differing size and height as described in said patent. It should also be here noted that the axial length of the bore in my yoke  312  is longer than the axial length of my drive gear  400  such that the pawls  322 ,  342 , will extend above the upper surface of the yoke  300  as the drive gear  400  is rotated in the bore  312 . It should be also noted that the orientation of the pawl chambers  320 ,  340 , and the pawls  322 ,  342 , respectively is similar to the orientation of the pawls and pawl chambers described in U.S. Pat. No. 5,738,192 such that once contact is made between either pawl and the teeth in drive gear  400 , the teeth of the pawl will slip into full engagement with the teeth in the drive gear  400  and the pawl will backload itself snugly against the yoke  300 , whereby to maximize torque while minimizing friction. 
   Control of the direction of driven rotation of the drive gear is achieved through a reverser system which includes a reverser  500 , a reverser link  502  and a reverser lever  504 . The reverser  500  comprises a substantially flat plate  510  having a centrally located bore  512 , an arcuate end  514 , and an opposing V-shaped end  516  provided with a upwardly extending cylindrical member  518 . Near the end  516  and projecting downwardly therefrom is a pawl selector  520  having a pair of flat spaced shoulders  522 ,  524 , disposed within the bore of the yoke  312 , near the pawl chambers  320 ,  340 , respectively. The selector  520  extends radially outwardly from the center of the bore  512  and is provided with an annular outer shoulder  526  comprising an annular arc concentric with the bore  512 . The bore  512  of the reverser  500  is snugly but movably disposed around the boss  118  between the yoke  310  and the upper housing  100 . The reverser  500  is sized so that it will rest on the top  360  of the yoke  312  with the annular member  520  projecting into the bore  312 . 
   The reverser link  502  comprises an elongated element  530  provided at one end with an aperture  532  sized in width for accepting the annular member  518  and in length for allowing linear movement of the member  518  in the aperture. The link  502  is provided at its other end with an upwardly projecting square post  534  and an annular section  536  sized for snug but movable disposition in the bore  122  of the upper housing  100 . The reverser lever  504  comprises an arm  540  and a downwardly extending post  542  having a cavity  544  sized for tight disposition about the post  534 . The annular member is snugly but slidably disposed in the aperture  532  for purposes presently more fully to appear. 
   The stops  124 ,  126 , are located on the upper surface of the housing  100  in such position that when the arm  540  of the reverser lever  504  is against the stop  124 , the shoulder  526  of the reverser  500  retains the pawl in the pawl chamber while the flat shoulder of the reverser  500  is presented to the other pawl chamber whereby the pawl is allowed access to the drive gear. Similarly, when the arm  540  of the reverser lever  504  is against the stop  126 , the shoulder  526  of the reverser  500  retains the pawl in the pawl chamber while the flat shoulder of the reverser  500  is presented to the other pawl chamber whereby the pawl is allowed access to the drive gear. Thus it should be apparent that the position of the reverser lever  504  with respect to the stops  124 ,  126 , controls the direction of driven rotation of the drive gear  400 . It should be here noted that the arc is which the annular member  518  moves as it is pivoted about the boss  118  and the arc in which the aperture  532  moves as the lever  504  is pivoted are overlapping arcs which overlap in the center of the pivotal movements whereby to require a slight but positive manual force to move the lever  504  into a selected position. 
   Operation: 
   In operation, the operator selects the direction of desired driven rotation and places the reverser arm  504  against the selected stop  124  or  126 . It should be here noted that as the post  542  is pivotally moved, the element  530  moves in an arcuate path and causes the plate  510  also to move in an arcuate path. The elliptical bore  532  is sized to permit the element  530  and the plate  510  to move freely without interference, but is sized in width to restrict the movement of the annular member  518  to a linear movement within the bore  532 . This restricted movement causes the arm  504  to be held firmly in place snugly in place against the particular stop  124  or  126  against which it is positioned, thereby preventing accidental disengagement of the reverser. By selecting the stop  124 , the arcuate member  520  of the reverser  500  will be positioned across the pawl chamber  340  and the pawl  342  will be thereby prevented from engaging the drive gear  400 . At that same time, the other end of the member  520  will not impede movement of the pawl  322  into engagement with the drive gear, and as the bell crank C is driven, the pawl  322  will drive the gear  400  in the chosen direction in the conventional manner. Similarly, by selecting the stop  126 , the arcuate portion  520  of the reverser  500  will be positioned across the pawl chamber  340  and the pawl  342  will be thereby prevented from engaging the drive gear  400 . At that same time, the opposing end of the member will not impede movement of the pawl  322  into engagement with the drive gear  400  as the bell crank C is driven, and the pawl  322  will drive the gear  400  in the opposing direction in the conventional manner. To applicant&#39;s knowledge and belief, this is the first positive locking mechanism ever developed for a reversible float head ratchet. 
   It should also be here noted that each of the springs  326 ,  346 , are sized in length such that spring bias is presented to the respective pawls  322 ,  342 , as they are urged toward engagement with the teeth of the gear  400  and that upon a tooth of the selected pawl engaging a gear tooth, the bias provided by the spring  326 ,  346 , is removed from the respective pawl and the shape of the tooth leads the respective pawl into complete engagement with the gear teeth. This unique and novel feature eliminates most of the wear on the pawl teeth and gear teeth caused by the return stroke of the yoke and greatly enhances the life of the tool. In addition, the individual teeth of the pawl and drive gear  400  become fully nested before driving force is applied causing the application of greater driving force to the drive gear and thereby increasing torque. The combination of the pawls having different sized teeth, and the gear teeth being constructed at the angles as described in my U.S. Pat. No. 5,738,192 together with the removal of spring bias during the major portion of the forward and return strokes of the yoke, greatly increases the life expectancy of the tool by a factor of at least four. 
   It should be apparent that changes and substitutions in the unique and novel arrangement, combination, assembly and interaction of the various parts and components shown and described herein may be made without departing from the nature and principle of my invention.