Abstract:
A handle for a hydraulically driven tool reduces the amount of heat transmitted to the user of the tool as a result of the high temperature fluid flowing through the inner body of the handle. The inner body is formed of a heat transmissive material which has at least one channel through which the fluid flows. The handle has a number of properties which reduces heat transmission to the user, including standoffs, ribs and fastener receiving extensions.

Description:
[0001]    This application is a continuation of U.S. Ser. No. 13/625,974, filed on Sep. 20, 2012 which claims the domestic benefit of U.S. provisional application Ser. No. 61/541,674, filed on Sep. 30, 2011, which disclosures are herein incorporated by reference in their entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure particularly relates to a handle for a hydraulically driven tool, such as a wrench or a drill, which reduces the amount of heat transmitted to the user of the tool. 
       BACKGROUND 
       [0003]    Existing hydraulic tools, such as hydraulic wrenches, generate heat as result of the use of high temperature hydraulic fluid passing through the tool. The user grips a grip which surrounds a metal valve body through which the high temperature hydraulic fluid passes. It is desirable to prevent the transfer of this heat to the user&#39;s hand. The prior art insulates the metal valve body with a PVC-based dip, which tends to be inadequate to prevent the passage of heat generated by the high temperature hydraulic fluid. In addition, the PVC-based dip is not very durable and is not easy to replace if the tool becomes damaged. 
         [0004]    Prior art tools have controlled flow in a circuit, and thus output motor torque in the circuit. A control for setting the torque to two discrete settings has been used in the prior art. This presents a disadvantage in that only two settings are provided. Other prior art tools have used a pressure compensated flow control mechanism with an infinite adjustment setting. Pressure compensated flow control mechanisms are costly to manufacture. 
         [0005]    A hydraulically driven tool is provided herein which provides improvements to existing tools and which overcomes the disadvantages presented by the prior art. Other features and advantages will become apparent upon a reading of the attached specification, in combination with a study of the drawings. 
       SUMMARY 
       [0006]    A handle for a hydraulically driven tool, such as a wrench or a drill, which reduces the amount of heat transmitted to the user of the tool is disclosed. The tool has a body formed of a heat transmissive material which has at least one channel through which a high temperature fluid flows. Heat is generated as a result of the fluid. The body includes a plurality of fastener receiving passageways therethrough; each passageway has a countersink provided at each end thereof. The handle is non-conductive and generally surrounds the body. The interior surface of the handle has a plurality of spaced apart standoffs extending therefrom. The standoffs contact the body and an air gap is formed between the interior surface and the body at locations where standoffs are not provided. This provides for a minimal amount of surface contact between the metal valve body and the non-conductive grip housing which reduces the amount of conduction from the heat transmissive body to the non-conductive handle, and thus to the user&#39;s hand which surrounds this area. In addition, the air gap allows air flow between the body and the handle for convection cooling of the body. The interior surface has a plurality of fastener receiving extensions, each having an aperture therethrough, which align with the respective passageways. The fastener receiving extensions seat within the countersinks and the fastener receiving extensions are smaller than the countersinks. As a result, the fastener receiving extensions do not contact the body to aid in minimizing the amount of heat transmitted to the handle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The organization and manner of the structure and operation of the disclosed embodiments, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, which are not necessarily drawn to scale, wherein like reference numerals identify like elements in which: 
           [0008]      FIG. 1  is a side elevational view of a tool which incorporates the features of the present invention; 
           [0009]      FIG. 2  is a cross-sectional view of the tool; 
           [0010]      FIG. 3  is a partial cross-sectional view of the tool; 
           [0011]      FIG. 4  is an alternate cross-sectional view of the tool; 
           [0012]      FIG. 5  is a perspective view of a grip assembly which forms a portion of the tool; 
           [0013]      FIG. 6  is an exploded perspective view of the grip assembly; 
           [0014]      FIG. 7  is a perspective view of a portion of a handle of the grip assembly; 
           [0015]      FIG. 8  is a side elevational view of the portion of the handle; 
           [0016]      FIG. 9  is a cross-sectional, perspective view of an inner body of the grip assembly; 
           [0017]      FIG. 10  is a side elevational view of the portion of the inner body; 
           [0018]      FIG. 11  is a side elevational view of a trigger spool assembly which forms a portion of the tool; 
           [0019]      FIG. 12  is a perspective view of a trigger spool which forms part of the trigger spool assembly; 
           [0020]      FIG. 13  is a perspective view of a bypass spool assembly which forms a portion of the tool; 
           [0021]      FIGS. 14 and 15  are cross-sectional views of the bypass spool assembly; 
           [0022]      FIG. 16  is a cross-sectional view of the tool; 
           [0023]      FIG. 17  is a perspective view of a work unit assembly which forms a portion of the tool; 
           [0024]      FIGS. 18-21  are various cross-sectional views of the tool; 
           [0025]      FIG. 22  is an exploded perspective view of a reversing spool assembly which forms a portion of the tool; 
           [0026]      FIG. 23  is a side elevational view of a reversing spool which forms a portion of the reversing spool assembly; and 
           [0027]      FIG. 24  is a cross-sectional view of the reversing spool assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    While the disclosure may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, a specific embodiment with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that as illustrated and described herein. Therefore, unless otherwise noted, features disclosed herein may be combined together to form additional combinations that were not otherwise shown for purposes of brevity. It will be further appreciated that in some embodiments, one or more elements illustrated by way of example in a drawing(s) may be eliminated and/or substituted with alternative elements within the scope of the disclosure. 
         [0029]    While the invention may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, a specific embodiment with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that as illustrated and described herein. Therefore, unless otherwise noted, features disclosed herein may be combined together to form additional combinations that were not otherwise shown for purposes of brevity. 
         [0030]    A fluid-operated tool  20 , such as a hydraulic wrench or drill, includes a fluid control system which provides for variable limitation of power output. The fluid control system provides multiple flow paths to provide for, among other things, selectable diversion of a portion of flow to a work unit assembly  22  of the tool  20 , and reversing the direction of the work unit assembly  22 . The tool  20  may be used by professional linemen who work outdoors under a variety of conditions, including blistering heat and intense cold. 
         [0031]    The tool  20  is a two-piece design formed of the work unit assembly  22  and a grip assembly  24 . The work unit assembly  22  has a series of ports  26 ,  28 ,  30 , see  FIG. 17 , which align with ports  32 ,  34 ,  36 , see  FIG. 5 , in the grip assembly  24 . O-rings  38  seal the connections between the ports  26 / 32 ,  28 / 34 ,  30 / 36 . 
         [0032]    The work unit assembly  22  includes an impact mechanism housing  40 , a motor housing  42  attached to the impact mechanism housing  40 , a gear motor  44  mounted in the motor housing  42 , and a chuck  46  attached to the gear motor  44  by a rotary impact mechanism  47 . A bit or other tool (not shown) is mounted to the chuck  46 . A plurality of channels  48 ,  50 ,  52 ,  54 ,  56 ,  58 , see  FIGS. 19-21 , are provided in the impact mechanism housing  40  to supply the gear motor  44  with hydraulic fluid as discussed in further detail herein. A motor reversing spool assembly  62 ,  FIGS. 21-24 , is mounted within channel  50  as discussed herein. 
         [0033]    As shown in  FIGS. 1-4 , the grip assembly  24  includes an inner valve body  64 , an outer grip housing  66   a,    66   b,  generally surrounding the inner valve body  64 , a trigger spool assembly  68  and a bypass spool assembly  70 . A plurality of channels  72 ,  74 ,  76 ,  78 ,  80   a / 80   b,    82 ,  84  are provided in the inner valve body  64  as discussed in further detail herein. The grip assembly  24  is attached to a supply (not shown) which provides hydraulic fluid to the tool  20 . 
         [0034]    The inner valve body  64  is formed of heat transmissive material, such as metal, preferably sand cast aluminum. The outer grip housing  66   a,    66   b,  which the user grips with his/her hand, is formed of a non-conductive material, preferably nylon, and includes first and second halves  66   a,    66   b.    
         [0035]    As shown in  FIG. 6 , the inner valve body  64  is formed of an elongated portion  86  which has a trigger spool platform  88  formed at the top end thereof, and a bypass valve platform  90  extending from the upper end of the trigger spool platform  88 . An axis  92  is defined through the centerline of the trigger spool platform  88  and extends from a front end  94  to a rear end  96  of the trigger spool platform  88 . 
         [0036]    As shown in  FIG. 2 , a pressure/pump port  98  and a return/tank port  100  are provided in the bottom end of the inner valve body  64 . An inlet channel  72  extends from the pressure/pump port  98  to a trigger spool channel  74  in which the trigger spool assembly  68  is mounted to provide for the flow of hydraulic fluid from the supply to the trigger spool channel  74 . An outlet channel  76  extends from the trigger spool channel  74  to the return/tank port  100  to provide for the flow of hydraulic fluid from the trigger spool channel  74  to the supply. The tool  20  is typically used in utility applications and is connected to a hydraulic power unit or auxiliary circuit in a boom truck or tractor via the ports  98 ,  100 . When the ports  98 ,  100  are not connected to the supply, suitable caps  99 ,  101  cover the ports  98 ,  100 . 
         [0037]    The trigger spool channel  74  extends along the axis  92  through the trigger spool platform  88 . The trigger spool channel  74  is generally cylindrical and extends from the front end  94  of the trigger spool platform  88  to the rear end  96  of the trigger spool platform  88 . A C-clip receiving groove  102 ,  FIG. 9 , is provided in the wall forming the trigger spool channel  74  proximate to the front end  94 . An enlarged O-ring receiving groove  104  is provided in the wall forming the trigger spool channel  74  proximate to the rear end  94 . The wall of the trigger spool channel  74  has an enlarged fluid chamber  106  provided at the junction between the trigger spool channel  74  and the inlet channel  72 ; an enlarged fluid chamber  108  provided at the junction between the trigger spool channel  74  and the outlet channel  76 ; and an enlarged fluid chamber  110  provided between and spaced from the enlarged fluid chamber  106  and the enlarged fluid chamber  108 . 
         [0038]    A bypass spool channel  78  extends parallel to the axis  92  through the bypass spool platform  90 . The bypass spool channel  78  is generally cylindrical and extends from a rear end  112  of the bypass spool platform  90  forwardly a predetermined distance. 
         [0039]    A transfer supply channel  80   a / 80   b  has a first portion  80   a  which connects the enlarged fluid chamber  110  of the trigger spool channel  74  to the bypass spool channel  78  and a second portion  80   b  which connects the bypass spool channel  78  to the outlet port  32  in the upper end of the grip assembly  24 . The outlet port  32  supplies fluid to the work unit assembly  22  of the tool  20 . 
         [0040]    A return transfer channel  82  connects port  34  to the enlarged fluid chamber  108  of the trigger spool channel  74  (see  FIG. 4 ); return transfer channel  84  connects port  36  to the enlarged fluid chamber  108  of the trigger spool channel  74  (see  FIG. 4 ). Ports  34 ,  36  receive fluid from the work unit assembly  22  as described herein. The bypass spool channel  78  is connected to the return transfer channel  82  at port  116 . 
         [0041]    As shown in  FIG. 6 , the inner valve body  64  has a pair of spaced apart fastener receiving passageways  118  extending through the trigger spool platform  88 , and another fastener receiving passageway  118  extending through the elongated portion  86  proximate to the bottom thereof. A countersink  121  is provided in each side of the inner valve body  64  at each end of the respective fastener receiving passageway  118 . 
         [0042]    The first and second halves  66   a,    66   b  of the grip housing are the mirror image of each other. The halves  66   a,    66   b  are designed to minimize the amount of heat transfer to the user of the tool  20  which results from the use of high temperature hydraulic fluid passing through the tool  20 . Halve  66   b  is shown in  FIGS. 7 and 8 . Each half  66   a,    66   b  has a wall  120  which mirrors the shape of half of the inner valve body  64 . Each wall  120  has an interior surface  122  which faces the inner valve body  64  and an exterior surface  124  which the user grasps with his/her hand. First, second and third fastener receiving extensions  126  extend from the interior surfaces  122  and each has an aperture  127  provided therethrough. A plurality of spaced apart standoffs  128  extend from the interior surfaces  122 . The standoffs  128  are preferably cross-shaped, however, other shapes are within the scope of the present invention. A plurality of spaced apart ribs  130  extend from the interior surfaces  122  at an upper end thereof. Each half  66   a,    66   b  can be formed by injection molding. 
         [0043]    When the halves  66   a,    66   b  are assembled with the inner valve body  64 , the halves  66   a ,  66   b  substantially cover the sides of the inner valve body  64 . The user grasps the area of the outer grip housing  66   a,    66   b  which surrounds the elongated portion  86  of the inner valve body  64 . The respective apertures  127  and passageways  118  align with each other such that the fastener receiving extensions  126  seat within the countersinks  121 , however, the fastener receiving extensions  126  are smaller than the countersinks  121  such that the fastener receiving extensions  126  do not contact the metal inner valve body  64 . The halves  66   a,    66   b  are assembled with the inner valve body  64  by a plurality of fasteners  132 , such as bolts, which pass through the apertures  127  and passageways  118 . The ribs  130  and the standoffs  128  contact the inner valve body  64 , and an air gap  129  is formed between the walls  120  and the inner valve body  64  at the points between the ribs  130  and the standoffs  128 . Preferably, the air gap  129  provides a spacing of  0 . 10 ″ between the walls  120  and the inner valve body  64 . Therefore, a minimal amount of surface contact is provided between the metal valve body  64  and the non-conductive grip housing  66   a,    66   b  which reduces the amount of conduction from the metal valve body  64  to the non-conductive grip housing  66   a,    66   b,  and thus to the user&#39;s hand which surrounds this area. In addition, the air gap  129  allows air flow between the inner valve body  64  and the grip housing  66   a,    66   b  for convection cooling of the inner metal valve body  64 . 
         [0044]    A soft grip material  67  preferably surrounds the halves  66   a,    66   b  of the grip housing. The soft grip material  67  helps to insulate the user from the heat generated by the hydraulic fluid. 
         [0045]    As shown in  FIGS. 3, 11 and 12 , the trigger spool assembly  68  includes a trigger spool  134  mounted in the trigger spool channel  74 , a spring assembly  136  for sealing the trigger spool  134  to the wall forming the trigger spool channel  74  and for biasing the trigger spool  134 , a trigger  138  attached by C-clips to the trigger spool  68  which extends from the trigger spool channel  74 , and a system adjusting spool assembly  140  provided in a rear end of the trigger spool  134 . The trigger  138  can be depressed by the user to move the trigger spool  134  backward and forward along the axis  92  in the trigger spool channel  74 . 
         [0046]    The trigger spool  134  is generally cylindrical. A first cylindrical section  146  of the trigger spool  134  extends rearwardly a predetermined distance from the front end  142 . An aperture  148  is provided through the first section  146  proximate to the front end  142  for connection of the trigger spool  134  to the trigger  138 . The first section  146  has a predetermined outer diameter which is smaller than the inner diameter of the trigger spool channel  74 . A flange  150  extends from the first section  146  at a position spaced from the front end  142 . The flange  150  has an outer diameter which is approximately the same as the inner diameter of the trigger spool channel  74 . A second section  152  extends from the rear end of the first section  146 . The second section  152  has an outer diameter which is approximately the same as the inner diameter of the trigger spool channel  74 . A third section  154  extends from the rear end of the second section  152 . The third section  154  has an outer diameter which is approximately the same as the first section  146  and thus is smaller than the inner diameter of the trigger spool channel  74 . A fourth section  156  extends from the rear end of the third section  154 . The fourth section  156  has an outer diameter which is less than the diameter of the second section  152 , but greater than the outer diameter of the third section  154 . A fifth section  158  extends from the rear end of the fourth section  156 . The fifth section  158  has an outer diameter which is approximately the same as the inner diameter of the trigger spool channel  74 , and is larger than the diameter of the fourth section  156 . 
         [0047]    A central bore  160 ,  FIG. 3 , extends from the rear end of the trigger spool  134  and extends axially forwardly through the fifth, fourth, third and second sections  158 ,  156 ,  154 ,  152 . The central bore  160  terminates in the second section  152 . The central bore  160  has a forward portion  162 , an intermediate portion  164  and a rearward portion  166 . The forward portion  162  extends through the second and third sections  152 ,  154  and is smaller in dimension than the intermediate portion  164  which extends through the fourth section  156  and part of the fifth section  158 . As a result, a seat  168  is formed between the forward and intermediate portions  162 ,  164  of the central bore  160 . A first set of four spaced apart passageways  170  extend radially outwardly from the forward portion  162  of the central bore  160  through the second section  152  of the trigger spool  134 . A second set of four spaced apart passageways  172  extend radially outwardly from the intermediate section  164  of the central bore  160  through the fourth section  156  of the trigger spool  134 . The rearward portion  166  of the central bore  160  is threaded and extends through the fifth section  158  of the trigger spool  134 . The rearward portion  166  of the central bore  160  is larger in dimension than the intermediate portion  164  of the central bore  160 , and as a result, a seat  173  is formed between the intermediate and rearward portions  164 ,  166 . The rear end  144  of the central bore  160  is open and thus is accessible to the user. 
         [0048]    The trigger spool  134  is mounted in the trigger spool channel  74  such that the front end of the trigger spool  134  extends outwardly from the front end of the tool  20  and connects to the trigger  138 . The spring assembly  136  seats between the flange  150  and the front end  94  of the trigger spool platform  88 . The spring assembly  136  includes a C-clip  174  which seats within the corresponding C-clip receiving groove  102  in the trigger spool channel  74 , a washer  176  which seats against the C-clip  174 , a spring  178  seated between the washer  176  and the flange  150 , and a rubber O-ring  180  which seats around the first section  146  between the flange  150  and the second section  152 . The trigger spool  74  can move axially along the trigger spool channel  74  by compressing the spring  178 . 
         [0049]    As shown in  FIG. 3 , the system adjusting spool assembly  140  is mounted within the trigger spool  134 . The system adjusting spool assembly  140  includes an adjusting spool  182  which seats within the intermediate and rearward sections  164 ,  166  of the central bore  160  and is sealed thereto by a rubber O-ring  183 . A C-clip  184  seats within a sloped recess  186  provided in the wall forming the rearward section  166 . A user can adjust the position of the adjusting spool  182  by screwing the adjusting spool  182  forward to move the adjusting spool  182  along the trigger spool channel  74  until ball  194  seats on seat  168 , or can be screwed in reverse until the adjusting spool  182  backs onto C-clip  184 . The C-clip  184  holds the adjusting spool  182  in position and prevents the removal of the adjusting spool  182  from the central bore  160 . A rubber O-ring  190  and back up ring  192  seat around the fifth section  158  and seat within the enlarged O-ring receiving groove  104 . The system adjusting spool assembly  140  includes a ball  194  which seats within the fourth and fifth sections  156 ,  158  of the central bore  160 . The ball  194  abuts against the forward end of the adjusting spool  182 . The ball  194  is moved by the user adjusting the position of the adjusting spool  182 . The ball  194  can be moved to seat against the seat  168 , thus closing the fluid communication between the forward portion  162  and the intermediate portion  164  (and thus the radial passageways  172 ), or can be moved away from the seat  168 , thus opening the fluid communication between the forward portion  162  and the intermediate portion  164  (and thus the radial passageways  172 ). 
         [0050]    When the trigger  138  is not depressed, the first set of passageways  170  are in alignment with the inlet channel  72  to receive hydraulic fluid. If the tool  20  is to be operated in an open-center configuration, the system adjusting spool assembly  140  is adjusted to move the ball  194  away from the seat  168 . As a result, the hydraulic fluid can continuously flow from the supply, through the inlet channel  72 , through the first set of passageways  170 , through the forward portion  162  of the central bore  160 , past the seat  168 , into the intermediate section  163  of the central bore  160 , through the second set of passageways  172  and into the return channel  76 . If the tool  20  is to be operated in a closed-center configuration, the system adjusting spool assembly  140  is adjusted to move the ball  194  against the seat  168 . As a result, the hydraulic fluid cannot flow into the intermediate section  163  of the central bore  160  and through the second set of passageways  172 . 
         [0051]    The bypass spool channel  78  is generally cylindrical and extends from a front end  196  of the bypass spool platform  90  to a rear end  198  of the bypass spool platform  90 . The front end of the bypass spool channel  78  is closed by an adjusting spool  200  as shown in  FIG. 16 . The rear end of the bypass spool channel  78  is open. 
         [0052]    The bypass spool assembly  70 , see  FIGS. 13 and 14 , includes a bypass spool  202  which is seated in the bypass spool channel  78 , and a knob  204 . The bypass spool  202  is generally cylindrical and has first and second opposite ends  206 ,  208 . The second end  208  of the bypass spool  202  extends outwardly from the bypass spool channel  78  and the knob  204  is mounted thereon by suitable means. A central bore  210  extends rearwardly from the first end  206  of the bypass spool  202  a predetermined distance. The open end of the central bore  210  is in fluid communication with the transfer channel  80   a,    80   b.  First and second passageways  212 ,  214 ,  FIGS. 14 and 15 , extend radially outwardly from the central bore  210  proximate to, but spaced from, the first end  206  thereof. The passageways  212 ,  214  are perpendicular to each other. The first passageway  212  has a smaller diameter than the second passageway  214 . The bypass spool  202  is sealed to the bypass spool channel  78  by a pair of spaced apart O-rings  216 . The bypass spool  202  can be rotated to be in one of three discrete positions within the bypass spool channel  78  by a user grasping the knob  204  and rotating it. In a first position, neither radial passageway  212 ,  214  aligns with the port  116  (which connects the bypass spool channel  78  to the return transfer channel  82 ) and hydraulic fluid does not flow through the central bore  210  to either radial passageway  212 ,  214 . This configuration provides for high revolutions per minute (rpm) of the gear motor  44  as the all of the hydraulic fluid flows to the work unit assembly  22 . In the second position, radial passageway  212  aligns with the port  116 , and hydraulic fluid flows through the central bore  210 , to the first, smaller radial passageway  212 , through port  116 , through the return channel  82 , through enlarged chamber  108 , and into return channel  76 . This configuration provides for medium revolutions per minute (rpm) of the gear motor  44  as most of the hydraulic fluid flows to the work unit assembly  22 , but some of the hydraulic fluid is diverted to the return channel  76 . In the third position, radial passageway  214  aligns with the port  116 , and hydraulic fluid flows through the central bore  210  to the second, larger radial passageway  214 , through port  116 , through the return channel  82 , through enlarged chamber  108 , and into return channel  76 . This configuration provides for low revolutions per minute (rpm) of the gear motor  44  as most of the hydraulic fluid is diverted to the return channel  76 , and some of the hydraulic fluid flows to the work unit assembly  22 . The work assembly unit  22 , is connected to the rotary impact mechanism  47 . Therefore, the hydraulic motor work assembly revolutions per minute (rpm) will govern the output torque of the tool  20 . 
         [0053]    As a result of this structure, the bypass spool assembly  70  is formed from a movable bypass spool  202  which form a valveless conduit. The bypass spool  202  is adapted for diverting a portion of the inlet flow from entering the work unit  22  directly to a return flow from the work unit  22 . The bypass spool  202  is movable about an axis generally orthogonal to an axis of movement of a motor reversing spool  230  discussed herein. 
         [0054]    As shown in  FIGS. 2 and 18 , the gear motor  44  includes a pair of gears  218 ,  220  which drive a shaft  222  that drives the chuck  46  by known means. The gears  218 ,  220  seat within a gear chamber  224  formed between the impact mechanism housing  40  and the motor housing  42 . The gears  218 ,  220  intermesh with each other and can be driven clockwise or counterclockwise in order to drive the chuck  46  in a clockwise or counterclockwise direction. First and second motor ports  226 ,  228  feed hydraulic fluid into the gear chamber  224  as discussed herein. 
         [0055]    As shown in  FIG. 3 , the impact mechanism housing  40  has a pressure supply channel  48  which extends from the inlet port  26  to a reversing spool channel  50  in which the motor reversing spool assembly  62  is mounted. As shown in  FIGS. 19 and 20 , the impact mechanism housing  40  further has a first transfer channel  52  extending from the reversing spool channel  50  to the first motor port  226 , and a second transfer channel  54  extending from the reversing spool channel  50  to the second motor port  228 . A first return channel  56  extends from the reversing spool channel  50  to the port  28  and connects with port  34  and first return transfer channel  82  in the grip assembly  24 . A second return channel  58  extends from the reversing spool channel  50  to the port  30  and connects with port  36  and second return transfer channel  84  in the grip assembly  24 . 
         [0056]    The motor reversing spool assembly  62 , which is shown in  FIGS. 22-24 , includes a reversing spool  230  having first and second ends  232 ,  234  and a central bore  236  extending from the first end  232  a predetermined distance, a spring biased relief valve assembly  238  mounted within the central bore  236 , a first handle  239  provided at the first end  232  of the reversing spool  230  which closes the open end of the central bore  236 , and second handle  241  provided at the second end  234  of the reversing spool  230 . Rubber O-rings and back-up rings  240 ,  242  seal the reversing spool  230  to the wall that forms the reversing spool channel  50 . The relief valve assembly  238  limits the torque of the gear motor  44 , and always dumps flow to port  30  when the relief valve assembly  238  is activated. 
         [0057]    The reversing spool  230  is generally cylindrical. A first section  244  extends from the front end  232  and has a predetermined outer diameter which is smaller than the inner diameter of the reversing spool channel  50 . A flange  246  extends from the first section  244  at a position spaced from the end  232  to provide a means for attaching the handle  239 . A second section  248  extends from the rear end of the first section  244 . The second section  248  has an outer diameter which is approximately the same as the inner diameter of the reversing spool channel  50 . A third section  250  extends from the rear end of the second section  248 . The third section  250  has an outer diameter which is less than the diameter of the second section  248  and thus is smaller than the inner diameter of the reversing spool channel  50 . A fourth section  252  extends from the rear end of the third section  250 . The fourth section  252  has an outer diameter which is the same as than the diameter of the second section  248 . A fifth section  254  extends from the rear end of the fourth section  252 . The fifth section  254  has an outer diameter which is the same as the third section  250 . A sixth section  256  extends from the rear end of the fifth section  254 . The sixth section  256  has an outer diameter which is the same as than the diameter of the second section  248  and the fourth section  252 . A seventh section  258  extends from the rear end of the sixth section  256 . The seventh section  258  has an outer diameter which is the same as the third and fifth sections  250 ,  254 . An eighth section  260  extends from the rear end of the seventh section  258 . The eighth section  260  has an outer diameter which is the same as than the diameter of the second, fourth and sixth sections  248 ,  252 ,  256 . The eighth section  260  has a groove  261  therein into which an O-ring is seated. A ninth section  263  extends from the eighth section  260  and has a flange  265  extending therefrom at a position spaced from the end  234  to provide a means for attaching the handle  241 . 
         [0058]    A first portion  262  of the central bore  236  extends from the first end  232  of the reversing spool  230  and extends axially forwardly through the first, second, third and fourth sections  244 ,  248 ,  250 ,  252 . A second portion  264  of the central bore  236  starts at the end of the first portion  262  and extend through the fifth portion  254 . The first portion  262  is larger in dimension than the second portion  264 . As a result, a seat  266  is formed between the first and second portions  262 ,  264 . A first set of diametrically opposed passageways  268   a,    268   b  extend radially outwardly from the first portion  262  through the third section  250 . A set of four spaced apart passageways  270  extend radially outwardly from the second portion  264  through the fifth section  254 . The reversing spool  230  is mounted in the reversing spool channel  50  such that the ends  232 ,  234 , and thus the handles  239 ,  241 , extend outwardly from the sides of the tool  20 . 
         [0059]    The spring biased relief valve assembly  238  is mounted in, and extends substantially the entire length of, the first portion  262  of the central bore  236 . The spring biased relief valve assembly  238  includes a spring  272  sandwiched between a pair of pins  274 ,  276 . Pin  274  abuts against the handle  239  and against a first end  278  of the spring  272 . Pin  276  abuts against a second end  280  of the spring  272 . Pin  276  has a shaft  282  which seats within the coils of the spring  272  and an enlarged cone-shaped head  284  which extends outwardly from the second end  280  of the spring  272 . A front surface  285  of the cone-shaped head  284  can be biased via the spring  272  to be in engagement with the seat  266  of the central bore  236 . A rear surface  287  of the cone-shaped head  284  is in engagement with the second end  280  of the spring  272 . The front surface  28  mated with seat  266 , and the rear surface  287  each define an area. Instead of being cone-shaped, other forms may be provided, for example, a stepped shape. 
         [0060]    A flange  286 ,  FIG. 3 , is retained by the underside of the impact mechanism housing  40  and extends into bypass spool channel  78  to prevent the removal of the bypass spool  202  from the bypass spool channel  78 , when connected to grip assembly  24 . 
         [0061]    Now that the specifics of the components of the tool  20  have been described, the method of using the tool  20  will be described. 
         [0062]    As discussed above, the tool  20  can be used in an open-center configuration or a closed-center configuration. To operate the tool  20  in an open-center configuration, the system adjusting spool assembly  140  is adjusted to move the ball  194  away from the seat  168 . As a result, the hydraulic fluid can continuously flow from the supply, through the inlet channel  72 , through the first set of passageways  170 , through the forward portion  162  of the central bore  160 , past the seat  168 , into the intermediate section  164  of the central bore  160 , through the second set of passageways  172  and into the return channel  76  even when the trigger  138  is not depressed. If the tool  20  is to be operated in a closed-center configuration, the system adjusting spool assembly  140  is adjusted to move the ball  194  against the seat  168 . As a result, the hydraulic fluid cannot flow into the intermediate section  164  of the central bore  160  and through the second set of passageways  172 . 
         [0063]    The user must then determine whether the tool  20  is be used to rotate the chuck  46  in a clockwise direction (thus using motor port  226 ), or a counterclockwise direction (thus using motor port  228 ). The motor reversing spool assembly  62  controls the direction the gear motor spins by diverting flow to either motor port  226 ,  228 . The motor port  226 ,  228  which is not pressurized dumps flow to one of ports  28 ,  30 , depending upon which motor port  226 ,  228  is pressurized. 
         [0064]    Operation of the tool is first described with the tool  20  placed into the configuration to rotate the chuck  46  in a counterclockwise direction, thus using motor port  226  as the supply to the gear chamber  224 . To do so, the reversing spool  230  is pushed until the handle  239  contacts the side of the impact mechanism housing  40 . Supply channel  48  aligns with the fifth section  254  of the reversing spool  230  and the radial passageways  270 . The fifth section  254  of the reversing spool  230  also aligns with transfer channel  52  which feeds fluid into motor port  226 . Motor port  228  feeds fluid into transfer channel  54 . 
         [0065]    In either the open-center configuration or the closed-center configuration, when the trigger  138  is depressed, the trigger spool  134  moves axially along the trigger spool channel  74  toward the front end of the tool  20 . The third section  154  of the trigger spool  134  aligns with the inlet channel  72  (the radial passageways  170  are moved out of alignment such that fluid cannot flow through the trigger spool  134 ), and the third and fourth sections  154 ,  156  span between the enlarged fluid chambers  106  and  110  to allow fluid communication between the enlarged fluid chambers  106  and  110 . The fifth section  158  aligns with the enlarged fluid chamber  108  and the return channel  76 . 
         [0066]    The hydraulic fluid flows from the supply, through port  98 , through the supply channel  72 , into enlarged fluid chamber  106 , between the third and fourth sections  154 ,  156  of the trigger spool  134  and the wall of the supply channel  72 , and then into enlarged fluid chamber  110 , through transfer channel  80   a,  into bypass spool channel  78 , into transfer channel  80   b , through ports  32  and  26 , into supply channel  48 , and into reversing spool channel  50 . In the configuration to rotate the chuck  46  in a counterclockwise direction, transfer channel  52  aligns with radial passageways  270 ; transfer channel  54  aligns with radial passageways  268   a,    268   b.  As a result, hydraulic fluid flows from supply channel  48 , around the fifth section  254  of the reversing spool  230  and through the radial passageways  270  and the second portion  264  of the central bore  236 , through transfer channel  52  and through motor port  226  to supply hydraulic fluid to the gear chamber  224  to rotate the gears  218 ,  220 , and thus the chuck  46 . Hydraulic fluid flows out of the gear chamber  224 , through motor port  228 , through transfer channel  54 , around the third section  250  of the reversing spool  230  and through the radial passageway  268   a  into first portion  262  of the central bore  260  and through the radial passageway  268   b,  to the return channel  58 . Hydraulic fluid then flows through ports  30 ,  36 , into return transfer channel  84 , into fluid chamber  108 , around fifth section  158  of trigger spool  134 , into return channel  76 , through port  100  to return to the supply. 
         [0067]    The relief valve assembly  238  is provided within the reversing spool  230  and limits the torque of the gear motor  44 . When resistance is seen by the gear motor  44 , the pressure from the hydraulic fluid builds in the second portion  264  of the central bore  236 . When enough pressure builds, the head  284  of the pin  276  unseats from seat  266  and fluid flows past the head  284  into the first portion  262  of the central bore  236  and out the radial passageways  268   a,    268   b , to the return channel  58  (that is, the fluid flows from the pressure side of the reversing spool  230  to the side exposed to the return channel  58 ). The pressure at which hydraulic fluid will be diverted by is determined by the force of the spring  272  and pressure in the return channel  58 . 
         [0068]    Therefore, when the reversing spool  230  is set to drive the tool  20  in reverse (counterclockwise), the rear surface  287  of the head  284  of the relief valve assembly  238  is exposed to the channel  54  from the gear chamber  224 . The channel  54  usually has some residual back pressure built up as a result of being used to return hydraulic fluid through the circuit to the supply. This pressure built up in the channel  54  acts on the rear surface  287  which creates a force. The pressure side force on the front surface  285  of the head  284  created by the pressure on that side must counteract this pressure on the rear surface  287  to unseat the head  284  and relieve the pressure. After leaving the area around the third section  250  of the reversing spool  230 , fluid flows to the trigger spool  134  where the fluid is drained out of the tool  20 . Once the pressure is relieved, the spring  272  expands to reseat the head  284  against the seat  266 . The relief valve  238  can be activated and closed as many times during operation as is necessary. 
         [0069]    The above operation assumes that the bypass spool  202  is in the position where no flow of hydraulic fluid is being diverted therethrough. In the situation where the bypass spool  202  is turned to the second position, radial passageway  212  aligns with the port  116  and hydraulic fluid flows through the central bore  210 , to the first, smaller radial passageway  212 , through port  116 , through the return channel  82 , through enlarged chamber  108 , and into return channel  76 . This configuration provides for medium revolutions per minute (rpm) of the gear motor  44  as most of the hydraulic fluid flows to the work unit assembly  22 , but some of the hydraulic fluid is diverted to the return channel  76 . In the situation where the bypass spool  202  is turned to the third position, hydraulic fluid flows through the central bore  210  to the second, larger radial passageway  214 , through port  116 , through the return channel  82 , through enlarged chamber  108 , and into return channel  76 . This configuration provides for low revolutions per minute (rpm) of the gear motor  44  as most of the hydraulic fluid is diverted to the return channel  76 , and some of the hydraulic fluid flows to the work unit assembly  22 . In this tool  20 , the bypass operation takes place in the line of flow before the hydraulic fluid reaches the motor reversing spool assembly  62 . The bypass valve assembly  70  connects the pressure side of the circuit to the return side of the circuit. The bypass valve assembly  70  regulates the revolutions per minute (rpm) of the gear motor  44  by diverting flow that would normally pass the motor reversing spool assembly  62  and power the gear motor  44 . By bypassing flow directly to the supply between the trigger spool assembly  68  and the motor reversing spool assembly  62 , the flow used to the power the gear motor  44  is reduced, thus reducing the revolutions per minute (rpm) of the gear motor  44 . In this tool  20 , speed regulates torque. 
         [0070]    Operation of the tool is now described with the tool  20  placed into the configuration to rotate the chuck  46  in a clockwise direction, thus using motor port  228  as the supply to the gear chamber  224 . To do so, the reversing spool  230  is pushed until the handle  241  contacts the side of the impact mechanism housing  40 . Supply channel  48  remains aligned with the fifth section  254  of the reversing spool  230  and the radial passageways  270 . Since the position of the reversing spool  230  has been shifted, the fifth section  254  of the reversing spool  230  now also aligns with transfer channel  54  which feeds fluid into motor port  228 . Transfer channel  52  aligns with the seventh section  258  of the reversing spool  230 . The radial passageway  268   b  remains aligned with the return channel  58 , but are not aligned with the channel  54 . 
         [0071]    In either the open-center configuration or the closed-center configuration, when the trigger  138  is depressed, the trigger spool  134  moves axially along the trigger spool channel  74  toward the front end of the tool  20 . The third section  154  of the trigger spool  134  aligns with the inlet channel  72  (the radial passageways  170  are moved out of alignment such that fluid cannot flow through the trigger spool  134 ), and the third and fourth sections  154 ,  156  span between the enlarged fluid chambers  106  and  110  to allow fluid communication between the enlarged fluid chambers  106  and  110 . The fifth section  158  aligns with the enlarged fluid chamber  108  and the return channel  76 . 
         [0072]    The hydraulic fluid flows from the supply, through port  98 , through the supply channel  72 , into enlarged fluid chamber  106 , between the third and fourth sections  154 ,  156  of the trigger spool  134  and the wall of the supply channel  72 , and then into enlarged fluid chamber  110 , through transfer channel  80   a,  into bypass spool channel  78 , into transfer channel  80   b , through ports  32  and  26 , and into supply channel  48 . Hydraulic fluid flows from supply channel  48 , around the fifth section  254  of the reversing spool  230  and through the radial passageways  270  and the second portion  264  of the central bore  236 , through transfer channel  54  and through motor port  228  to supply hydraulic fluid to the gear chamber  224  to rotate the gears  218 ,  220 , and thus the chuck  46 . Hydraulic fluid flows out of the gear chamber  224 , through motor port  226 , through transfer channel  52 , around the seventh section  258  of the reversing spool  230 , to the return channel  58 . Hydraulic fluid then flows through ports  30 ,  36 , into return transfer channel  84 , into fluid chamber  108 , around fifth section  158  of trigger spool  134 , into return channel  76 , through port  100  to return to the supply. 
         [0073]    When resistance is seen by the gear motor  44 , the pressure from the hydraulic fluid builds in the second portion  264  of the central bore  236 . When enough pressure builds, the head  284  of the pin  276  unseats from seat  266  and fluid flows past the head  284  into the first portion  262  of the central bore  236  and out the radial passageways  268   a,    268   b,  to the return channel  58  (that is, the fluid flows from the pressure side of the reversing spool  230  to the side exposed to the return channel  58 ). The pressure at which hydraulic fluid will be diverted by is determined by the force of the spring  272 . Once the pressure is relieved, the spring  272  expands to reseat the head  284  against the seat  266 . The relief valve  238  can be activated and closed as many times during operation as is necessary. 
         [0074]    When the reversing spool  230  is positioned to drive the tool  20  forward (clockwise) the fluid return channel switches and therefore, motor  44  does not drain fluid behind the relief valve  238 . The fluid drains directly to the return channel  56  and proceeds to enlarged fluid chamber  108 . Since there is a pressure drop (Δp) from the loss of energy of the fluid between these locations, the pressure around the trigger spool  134  in chamber  108  is less than the pressure in the area around the reversing spool  230  in channel  56 . The channel  58  is exposed to the rear surface  287  of the pin  276  on the opposite end of the reversing spool  230 . Since fluid does not pass behind the pin  276  from the motor  44 , the pressure behind the pin  276  is the same as the pressure in the chamber  108  around the trigger spool  134 . 
         [0075]    The above operation assumes that the bypass spool  202  is in the position where no flow of hydraulic fluid is being diverted therethrough. In the situation where the bypass spool  202  is turned to the second position, radial passageway  212  aligns with the port  116  and hydraulic fluid flows through the central bore  210 , to the first, smaller radial passageway  212 , through port  116 , through the return channel  82 , through enlarged chamber  108 , and into return channel  76 . This configuration provides for medium revolutions per minute (rpm) of the gear motor  44  as most of the hydraulic fluid flows to the work unit assembly  22 , but some of the hydraulic fluid is diverted to the return channel  76 . In the situation where the bypass spool  202  is turned to the third position, hydraulic fluid flows through the central bore  210  to the second, larger radial passageway  214 , through port  116 , through the return channel  82 , through enlarged chamber  108 , and into return channel  76 . This configuration provides for low revolutions per minute (rpm) of the gear motor  44  as most of the hydraulic fluid is diverted to the return channel  76 , and some of the hydraulic fluid flows to the work unit assembly  22 . In this tool  20 , the bypass operation takes place in the line of flow before the hydraulic fluid reaches the motor reversing spool assembly  62 . The bypass valve assembly  70  connects the pressure side of the circuit to the return side of the circuit. The bypass valve assembly  70  regulates the revolutions per minute (rpm) of the gear motor  44  by diverting flow that would normally pass the motor reversing spool assembly  62  and power the gear motor  44 . By bypassing flow directly to the supply between the trigger spool assembly  68  and the motor reversing spool assembly  62 , the flow used to the power the gear motor  44  is reduced, thus reducing the speed output of the gear motor  44 . 
         [0076]    Therefore, the same relief valve  238  is capable of being activated to relieve pressure when the gear motor  44  is being operated to drive the tool  20  in reverse (counterclockwise) and to drive the tool  20  forward (clockwise). In reverse, a higher pressure is provided behind the head  284  of the relief valve  238  because the head  284  is exposed to the pressure of the fluid as it directly leaves the channel  54 . In the forward operation, the relief valve  238  is not exposed to the return flow from the gear motor  44 . Therefore, the rear surface  287  of the relief valve  238  is only exposed to pressure in the channel  58  which is equal to pressure in chamber  108  since it is not exposed to channel  54 . Since the pressure on the channel  58  is less in forward operation than in reverse, the orientation for reverse operation causes the relief valve  238  to have a higher pressure on the rear surface  287  than in the forward orientation. This provides a higher force on the rear surface  287  in that orientation and therefore, a higher pressure is needed in second portion  264  of the central bore  236  to open the relief valve  238 . When the reversing spool  230  is positioned to drive the tool  20  forward (clockwise), the pressure needed to unset the pin  276  is less than in the reverse (counterclockwise). This is done by exposing the dumping side of the relief valve  238  to different pressures, thus in the reverse (counterclockwise) rotating position, more pressure works on the rear area of the pin  276 . Thus, more pressure must work on the front surface  28  to unseat the pin  276 . This is useful when hydraulic motor torque differential settings are needed in forward and reverse. 
         [0077]    As a result of the structure of the tool  20 , the trigger spool assembly  68  is downstream of the inlet port  98  and controls the flow of fluid to the work unit  22 . The bypass valve assembly  70  is disposed downstream of the trigger spool assembly  68 . The motor reversing assembly  62  is disposed downstream of the bypass valve assembly  70 . 
         [0078]    While several components are referred to as a “spool” in the preferred embodiment disclosed herein, the spools may be any component, such as, in non-limiting embodiments, a valve, that otherwise provides for the functions described herein. Similarly, other “spools” disclosed herein may be suitably replaced by other components, such as other types of valves. 
         [0079]    In addition to the foregoing aspects of the fluid control system described, it is within the teachings herein to include diversion from the flow of oil at selected locations for other purposes. That is, in addition to the features above, the fluid control system  1  may contain bleeder valves or other features that provide oil supply for such purposes as tool lubrication. 
         [0080]    One skilled in the art will recognize that the invention disclosed herein is not limited to use in a variable torque impact wrench. For example, the fluid control system disclosed herein may be used in wrenches, grinders, drills, chain saws, pole saws, circular saws, pruners, tampers, and other tools having similar power requirements. As another example, features of the present invention could be used in a pneumatic tool rather than a hydraulic tool. Therefore, it is within the teachings contained herein to use this invention, and variations thereof, in other applications. 
         [0081]    While particular embodiments are illustrated in and described with respect to the drawings, it is envisioned that those skilled in the art may devise various modifications without departing from the spirit and scope of the appended claims. It will therefore be appreciated that the scope of the disclosure and the appended claims is not limited to the specific embodiments illustrated in and discussed with respect to the drawings and that modifications and other embodiments are intended to be included within the scope of the disclosure and appended drawings. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the disclosure and the appended claims.