Abstract:
A uniquely designed torque wrench having a torque body, the torque body attached to a drive head, the drive head entering a contracted stated during extension of a rod of a hydraulic cylinder, and entering an expanded state during the retraction of the rod of a hydraulic cylinder.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation of U.S. patent application Ser. No. 13/568,217, filed Aug. 7, 2012, which is a non-provisional application of U.S. Provisional Application Ser. No. 61/611,791, filed Mar. 16, 2012, priority of which two applications are hereby claimed and which two applications are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    In one embodiment, the method and apparatus relate to torque tools. More particularly, in one embodiment is provided a method and apparatus wherein a ratcheting hydraulic torque wrench is used for tightening and loosening irregularly shaped items (e.g., non-nuts such as cylindrically or oblong shaped items which where a drive head frictionally connects to the item to be loosened or tightened providing a turning torque, and the amount of force of the frictional connects varies directly with the amount of turning torque provided by the wrench. 
         [0003]    In one embodiment the torque wrench is provided with a head having a gate that can be opened allowing the drive head to be connected to the item to be tightened or loosened along the longitudinal axis of the item. After the drive head is placed on the item it can be placed in a locked condition allowing the frictional drive mechanism to be engaged. 
         [0004]    One prior art wrench is the type shown in U.S. Pat. No. 6,279,427 titled “Crosshead Jam Nut Torque Wrench, which is incorporated herein by reference, and discloses a gated drive head. However, such gated drive head does not provide a frictional driving force which varies directly with the amount of turning torque supplied by the wrench. Also incorporated herein by reference is U.S. Pat. No. 5,097,730. 
         [0005]    While certain novel features of this invention shown and described below are pointed out in the annexed claims, the invention is not intended to be limited to the details specified, since a person of ordinary skill in the relevant art will understand that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation may be made without departing in any way from the spirit of the present invention. No feature of the invention is critical or essential unless it is expressly stated as being “critical” or “essential.” 
       BRIEF SUMMARY 
       [0006]    In one embodiment is provided torque wrench having a wrench body, the wrench body rotationally attached to squeezing frictional drive head, with the drive head having an expanding and contracting opening, for fitting over an item to be tightened or loosened, such as a joint of tubing or pipe wherein the drive head can enter a squeezing state and non-squeezing states. In one embodiment the squeezing and non-squeezing states are based on the direction of turn of the drive head relative to the torque body, with opposite relative rotations providing opposite squeezing states—squeezing versus non-squeezing. 
         [0007]    In one embodiment is provided a hydraulic cylinder secured between the wrench body and the squeezing drive head so that under hydraulic pressure, the head is both rotated and caused to squeeze causing frictional forces to be created between the squeezing drive head and the item to be tightened or loosened. In one embodiment the frictional forces create sufficient forces to rotate to the item to be tightened or loosened. 
         [0008]    In one embodiment is provided a hydraulic cylinder secured between the wrench body and the squeezing drive head so that under hydraulic pressure, the head is both rotated and caused to enter a squeezing state such squeezing state causing increased frictional forces to be created (relative to a non-squeezing state) between the squeezing drive head and the item to be tightened or loosened. In one embodiment the frictional forces create sufficient torsional forces to rotate to the item to be tightened or loosened. 
         [0009]    In one embodiment the drive head can comprise first and second portions which are pivotally connected to each other at a first end, and a turning torque placed on the first portion tends to cause the first portion to rotate in a first direction, a torque is also placed on the second portion tending to cause the second portion to rotate in a second direction, the second direction being in substantially the opposite direction as the first direction. 
         [0010]    In one embodiment the drive head can be provided with a gate portion which can be disengaged and opened, to define a gate which can allow item to be tightened or loosened to be positioned inside the interior of the drive head while the drive head remains between the longitudinal ends of the item to be tightened or loosened. The item to be tightened or loosened can be positioned within the interior of the open drive head, and the gate portion of the drive head placed in a squeezing state forming a frictionally squeezing drive head. 
         [0011]    In one embodiment is provided a fluid powered torque wrench having 
         [0012]    (a) a torque body; 
         [0013]    (b) a drive head rotationally connected to the torque body; 
         [0014]    (c) a fluid cylinder operatively connected to the drive head and the torque body; 
         [0015]    (d) with the drive head having a relaxed state with an opening of a first size, for fitting over an item to be tightened or loosened such as a joint of tubing or pipe, 
         [0016]    (e) wherein the fluid cylinder during the process of causing rotation of the drive head in a first direction causes the drive head to enter a squeezing state wherein the opening reduces to a second size which is smaller than the first size, thereby causing frictional forces between the drive head and the item to be tightened or loosened during turning in the first direction, and 
         [0017]    (f) wherein the fluid cylinder in the process of causing rotation of the drive head in a second direction, which second direction is the opposite direction of the first direction, causes the drive head to enter a relaxed state wherein the frictional forces between the drive head and the item to be tightened or loosened are substantially reduced in relation to the frictional forces generated during the squeezing state. 
         [0018]    In one embodiment is provided a fluid powered torque wrench having 
         [0019]    (a) a torque body; 
         [0020]    (b) a drive head rotationally connected to the torque body; 
         [0021]    (c) a fluid cylinder operatively connected to the drive head and the torque body; 
         [0022]    (d) with the drive head having a relaxed state with an opening of a first size, for fitting over an item to be tightened or loosened such as a joint of tubing or pipe, 
         [0023]    (e) wherein the fluid cylinder during the process of causing rotation of the drive head in a first direction causes the drive head to enter a squeezing state wherein the opening reduces to a second size which is smaller than the first size, thereby causing frictional forces between the drive head and the item to be tightened or loosened during turning in the first direction, and 
         [0024]    (f) wherein the fluid cylinder in the process of causing rotation of the drive head in a second direction, which second direction is the opposite direction of the first direction, causes the drive head to enter a relaxed state wherein the opening is of a larger size than the second size. 
         [0025]    In one embodiment, the drive head, rotationally connected to the torque body, can comprise a four bar linkage mechanism comprising a fulcrum, link, first section, and second section wherein the first and second sections are pivotally connected to each other, the link is pivotally connected to the first section and fulcrum, and the fulcrum is pivotally connected to the second section. In one embodiment fluid rod/cylinder can be pivotally connected to fulcrum and wrench body. In one embodiment extension of rod relative to cylinder will cause the drive head to enter a contracting state and also cause rotation of drive head relative to wrench body in a first direction. In one embodiment retraction of rod relative to cylinder will cause the drive head to enter an expanding state (causing relative expansion of the cross sectional size of the interior space of drive had) and also cause rotation of drive head relative to wrench body in the second direction which is the opposite of the first direction, and also cause drive head to slide relative to item to be loosened or tightened (i.e., not turn item during a retraction stroke of rod relative to cylinder). In one embodiment such relative expansion of interior space limited/restricted to a maximum extent. In one embodiment during a retraction stroke, the maximum amount of relative expansion of interior space during an expansion stroke in percent area (compared to the cross sectional area of interior space&#39;s  395  size during extension stroke of rod  1100 ) is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, and 35 percent. In various embodiments the maximum amount of relative expansion is between about any two of the above specified relative percentages. 
         [0026]    In one embodiment the cross sectional area of the interior can be defined by the area circumscribed by the interior portions of the first and second sections of the drive head. Because there may be a gap between the ends of the interior portions of first and second sections of the drive head (such as when in an expanded state), the area circumscribed can be determined by extrapolating the end of the interior portion of the first section of the drive head onto the end of the interior portion of the second section of the drive head. Such extrapolation can be by a method of curve fitting such as using standard curve fitting (e.g., the best fit curve fit) considering the shape of the interior portion of the first section of the drive head and the shape of the interior portion of the second section of the drive head. Alternatively a straight line can be drawn between the ends of the interior portion of the first and second sections of the drive head. 
         [0027]    In one embodiment, during a retraction stroke of rod relative to cylinder, the four bar linkage mechanism of drive head formed by lever fulcrum, link, first section, and second section will cause lever fulcrum to rotate relative to drive head (and relative to second section) causing interior space of drive head to enter an expanding state, and during extension of rod relative to cylinder, lever fulcrum will rotate in the opposite direction (compared to retraction of rod relative to cylinder) causing drive head to enter a contracted state. In one embodiment the maximum sweep (relative to drive head) of lever fulcrum during retraction and extension strokes of rod relative to cylinder in degrees about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, and 35 degrees. In various embodiments the maximum amount of relative rotation of lever fulcrum  600  is between about any two of the above specified relative degree measurements. 
         [0028]    In one embodiment during an extension stroke of rod relative to cylinder, the drive head has a maximum extension stroke area of contact with item to be tightened or loosened, and during a retraction stroke of rod relative to cylinder, drive head has a minimum retraction stroke area of contact with item  1300 . In one embodiment the maximum extension stroke area of contact is greater than the minimum retraction stroke area of contact. In various embodiments the extension stroke maximum area of contract is at least 1.1, 1.2, 1.3, 1.4, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 times the retraction stroke minimum area of contact. In various embodiments the ratio of these to areas is between any two of the above specified ratio measurements. 
         [0029]    In one embodiment, during a retraction stroke of rod relative to cylinder, the four bar linkage mechanism of drive head (formed by fulcrum, link; first section, and second section) will enter an expanding state where rotation of first section relative to second section about pivot point occurs in the opposite direction of rotation of the drive head during retraction. In one embodiment such relative expanding relative rotation between first section and second section is limited/restricted to a maximum extent. In one embodiment during a retraction stroke of rod relative to cylinder, the maximum amount of relative rotation between first section and second section in degrees is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, and 35 degrees. In various embodiments the maximum amount of relative rotation is between about any two of the above specified relative degree measurements. In one embodiment before reaching any maximum amount of relative rotation between first section and second section (with respect to the four bar link system), the increasing reaction forces arising from fulcrum lever attempting to expand first section relative to second section increase to such an extent that frictional forces between track and arcuate slot (along with possible frictional forces between first section and/or second section relative to item to be tightened or loosened) are overcome allowing drive head to rotate/ratchet back into an initial starting drive position to be ready for the next extension stroke of rod relative to cylinder. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
           [0031]      FIG. 1  is a side view of one embodiment showing the wrench mounted on an item to be loosened. 
           [0032]      FIGS. 1-5  show various sequences of using the wrench of  FIG. 1  to loosen a pipe, wherein  FIGS. 2 and 3  sequentially show extension of the hydraulic cylinder, and  FIGS. 4 and 5  sequentially show retraction of the hydraulic cylinder. 
           [0033]      FIG. 6  shows the wrench of  FIG. 2  being placed on a pipe to loosen or unscrew such pipe from a threaded connection. 
           [0034]      FIG. 7  shows the wrench of  FIG. 2  being placed on a pipe to tighten or screw in such pipe to a threaded connection. 
           [0035]      FIG. 8  is an exploded perspective view of the components of the wrench of  FIG. 1 . 
           [0036]      FIGS. 9-13  are various views of the body of the wrench of  FIG. 1 . 
           [0037]      FIGS. 14 ,  15 , and  16  are respectively perspective, front and rear views of the fulcrum lever for the wrench of  FIG. 1 . 
           [0038]      FIGS. 17-21  are perspective views of the first and second sections of the drive head of the wrench of  FIG. 1 . 
           [0039]      FIG. 22  is a perspective view of the drive head of the wrench of  FIG. 1  showing first and second sections along with the clamping/squeezing mechanism shown in a non-squeezing state, wherein the drive head is positioned to loosen an item. 
           [0040]      FIG. 23  is a front perspective view of the drive head of the wrench of  FIG. 1  showing first and second sections along with the clamping/squeezing mechanism. 
           [0041]      FIG. 24  is a rear perspective view of the drive head of the wrench of  FIG. 1  showing first and second sections along with the clamping/squeezing mechanism. 
           [0042]      FIG. 25  is a perspective view of the drive head of the wrench of  FIG. 1  showing the first and second sections along with the clamping/squeezing mechanism shown in a squeezing state, wherein the drive head is positioned to loosen an item. 
           [0043]      FIG. 26  is a perspective view of the drive head of the wrench of  FIG. 1  showing the first and second sections along with the clamping/squeezing mechanism shown in anon-squeezing state, wherein the drive head is positioned to tighten an item. 
           [0044]      FIG. 27  is a perspective view of the drive head of the wrench of  FIG. 1  showing the first and second sections along with the clamping/squeezing mechanism shown in a squeezing state and with an item to be tightened positioned in the interior of the drive head. 
           [0045]      FIGS. 28 and 29  are schematic diagrams of the four bar linkage system for the squeezing drive head of the wrench of  FIG. 1  shown respectively in expanded and squeezed or compressed states. 
           [0046]      FIG. 30  is a force diagram of the wrench of  FIG. 1 . 
           [0047]      FIG. 31  shows an alternative embodiment of the wrench of  FIG. 1 , wherein the drive head includes one or more frictionally enhancing elements. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0048]    Detailed descriptions of one or more preferred embodiments are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in any appropriate system, structure or manner. 
         [0049]      FIG. 1  is a side view of one embodiment showing the wrench  10  mounted on an item  1300  to be loosened.  FIGS. 1-5  show various sequences of using wrench  10  to loosen a pipe  1300 , wherein  FIGS. 2 and 3  sequentially show extension (schematically indicated by arrow  304 ) of the hydraulic cylinder  1000 , and  FIGS. 4 and 5  sequentially show retraction (schematically indicated by arrow  304 ′) of the hydraulic cylinder  1000 . 
         [0050]      FIGS. 1-3  show various sequences of using wrench  10  to loosen a pipe  1300 . In  FIG. 1  rod  1100  is fully retracted. In  FIG. 2 , rod  1100  is partially extended. In  FIG. 3 , rod  1100  is almost fully extended. 
         [0051]      FIGS. 4 ,  5 , and then 1 show various sequences of using wrench  10  to tighten a pipe  1300 . In  FIG. 1  rod  1100  is fully retracted. In  FIG. 4 , rod  1100  is beginning to retract. In  FIG. 5 , rod  1100  is continuing to retract. In  FIG. 1  rod  1100  is fully retracted, and is now fully retracted and ready for the next extension cycle. 
         [0052]      FIG. 6  shows wrench  10  being placed on a pipe  1300  to loosen or unscrew such pipe from a threaded connection.  FIG. 7  shows wrench  10  being placed on a pipe  1300  to tighten or screw in such pipe to a threaded connection. A user can place wrench  10  on an item in the desired configuration to loosen or tighten such item. 
         [0053]      FIG. 8  is an exploded perspective view of the major components of wrench  10 . 
         [0054]    Generally, torque wrench  10  can include a wrench body  100  having a cooperating drive head portion  390  on a first end  110  and a rear body portion on its second end  120 . Wrench body  100  can also include a hydraulic cylinder  1000  and piston rod  1100  for providing reciprocating motive force between body  100  and drive head  390 . 
         [0055]      FIGS. 9-13  are various views of the body  100  of wrench  10 . Body  100  can comprise first end  110 , second end  120 , and generally arcuate slot  130 . 
         [0056]      FIGS. 14 ,  15 , and  16  are respectively perspective, front and rear views of the fulcrum lever  600  for wrench  10 . Fulcrum lever  600  can comprise first end  610 , second end  620  with first and second prongs  624 , 628  spanning the second end  620 . On first end can be pivot point/opening  612 . On first and second prongs  624 , 628  can be pivot points/openings  625 , 628 . Between opening  612  and openings  625 , 629  can be pivot point/opening  640 . 
         [0057]      FIGS. 17-21  are perspective views of the first  400  and second  500  sections of drive head  390 . First section  400  can comprise first end  410  with pivot point/opening  414 , second end  420  with pivot point/opening  424 , and handle  450 . Second section  500  can comprise first end  510 , second end  520  with pivot point/opening  524 , track  570 , and arm  550  with pivot point/opening  560 . Pivot point  424  can be pivotally connected to pivot point  524 . 
         [0058]      FIG. 22  is a perspective view of drive head assembly  390  of wrench  10  showing first  400  and second  500  sections along with the clamping/squeezing mechanism (lever  600  with links  700 , 720 ) shown in anon-squeezing state, wherein the drive head  390  is positioned to loosen an item  1300  (item  1300  is not shown in  FIG. 16  however).  FIGS. 23 and 24  are respectively front and rear perspective views of drive head  390  showing first  400  and second  500  sections along with the clamping/squeezing mechanism. 
         [0059]    Drive head  390  can comprise first section  400 , second section  500  pivotally connected to first section  400 , and fulcrum lever  600  which is pivotally connected to second section  500  via arm  550  and pivot point  640 , and pivotally connected to first section  400  through pivoting links  700 , 720 . In one embodiment squeezing head  390  comprises first section  400 , second section  500 , fulcrum lever  600 , and at least one link  700  (preferably with second link  720 ). Preferably first  400  and second  500  sections are arcuate in shape. First section  400  can be pivotally connected to second section  500 , and when connected define an expandable and shrinkable interior space  395 . Fulcrum lever  600  can be pivotally connected to arm  550  of second section  500 . Links  700  and  720  can be pivotally connected to first section  400  at first end  410  through opening  414 , and also be pivotally connected to fulcrum lever  600  at second end  620  respectively at openings  628  and  625 . In this manner of connection fulcrum  600 , links  700 , 720 ; first section  400 , and second section  500  form a four bar linkage system allowing drive head to have shrinking and expanding interior space  395  with the fulcrum lever  600  being the driving link. 
         [0060]      FIG. 25  is a perspective view of the drive head  390  showing the first  400  and second  500  sections along with the clamping/squeezing mechanism shown in a squeezing state, wherein the drive head  390  is positioned to loosen an item  1300 . 
         [0061]      FIG. 26  is a perspective view of the drive head  390  of wrench  10  showing first  400  and second  500  sections along with the clamping/squeezing mechanism shown in a non-squeezing state, wherein the drive head  390  is positioned to tighten an item.  FIG. 27  is a perspective view of the drive head  390  of wrench  10  showing the first  400  and second  500  sections along with the clamping/squeezing mechanism shown in a squeezing state and with an item  1300  to be tightened positioned in the interior of the drive head. 
         [0062]    As indicated in  FIGS. 1-5  wrench  10  can include hydraulic cylinder  1000  which houses a piston internally on a rod  1100  with the hydraulic cylinder being  1000  fluidly powered with a pair of hydraulic lines (lines are not shown for clarity but a person of ordinary skill in the art would understand the operation of a hydraulic cylinder/piston arrangement) so that as hydraulic fluid is pumped into cylinder  1000  via a first line of the pair of hydraulic lines, the piston and rod  1100  is moved outwardly from the cylinder  1000  and the arm member  550  is moved in the direction of arrow  308  thus imparting rotation to drive head  390 , and as hydraulic fluid is pumped into cylinder  1000  (in the opposite direction as the first line) via a second line of the pair of hydraulic lines, the piston and rod  1100  is retracted inwardly into the cylinder  1000  and the arm member  550  is moved in the opposite direction of arrow  308  thereby resetting drive head  390  for another movement cycle. 
         [0063]    Drive head  390  can be slidably connected to body  100  via cooperation between track  570  of second section  500 , and arcuate slot  130  of body  100 . 
         [0064]    As sequentially shown in  FIGS. 1-3 , the extension turning mechanics of drive head  390  can occur as follows. Rod  1100  extending in the direction of arrow  304  imposes a force on first portion  610  of fulcrum lever  600  (in the direction of arrow  304 ) creating a turning torque on drive head  390  (in the direction of arrow  308 ) because fulcrum lever  600  is pivotally connected to drive head  390  through arm member  550 . Rod  1100  imposing a force on first portion  610  of fulcrum lever  600  also creates a turning torque (in the direction of arrow  312 ) on fulcrum lever  600  about its pivot point on arm member  550  (located at opening  640 ), which in turn creates a pulling force on links  700 , 720  (in the direction of arrow  316 ), which in turn cause a pulling force on first section  400  (in the direction of arrow  316 ), which in turn causes a torsional turning torque on first section relative to second section about their pivot point  420 , 520  (in the direction of arrow  324 ). The torsional force of first section  400  relative to second section  500  (in the direction of arrow  324 ) along with the pulling force on first section  400  (in the direction of arrow  320 ) causes first section  400  to close relative to second section  500  (schematically indicated by arrows  328 ) causing a frictional force to be generated between an item to be loosened or tightened  1300  and drive head  390  which frictional force allows drive head  390  to actually turn item  1300  (in the direction of arrows  310 ) as track  570  of second section  500  moves within arcuate slot  130  of body  100  (in the direction of arrow  308 ). 
         [0065]    As sequentially shown in  FIGS. 4 ,  5 , and then 1, the retraction ratcheting mechanics of drive head  390  can occur as follows. Rod  1100  retracting in the direction of arrow  304 ′ imposes a force on first portion  610  of fulcrum lever  600  (in the direction of arrow  304 ′) creating a turning torque on drive head  390  (in the direction of arrow  308 ′) because fulcrum lever  600  is pivotally connected to drive head  390  through arm member  550 . Rod  1100  imposing such force on first portion  610  of fulcrum lever  600  also creates a turning torque (in the direction of arrow  312 ′) on fulcrum lever  600  about its pivot point on arm member  550  (located at opening  640 ), which in turn creates a pushing force on links  700 , 720  (in the direction of arrow  316 ′), which in turn cause a pushing force on first section  400  (in the direction of arrow  316 ′), which in turn causes a torsional turning torque on first section relative to second section about their pivot point  420 , 520  (in the direction of arrow  324 ′). The torsional force of first section  400  relative to second section  500  (in the direction of arrow  324 ′) along with the pushing force on first section  400  causes first section  400  to open relative to second section  500  (schematically indicated by arrows  330 ) minimizing any a frictional force between item to be loosened or tightened  1300  and drive head  390  which allows drive head  390  to turn relative to item  1300  (in the direction of arrow  308 ′) as track  570  of second section  500  moves within arcuate slot  130  of body  100 —without turning item  1300  for the next extension cycle of rod  1100  (this relative movement of drive head  390  and item  1300  is called the ratcheting movement of drive head). 
         [0066]      FIG. 2  is a side view showing rod  1100  extending in the direction of arrow  304  causing drive head  390  to enter a contracting/squeezing state thereby causing plurality of gripping inserts  490 , 590  to frictionally connect with item  1300 , thereby causing item  1300  to turn in the direction of arrow  310  (with arrow  1310  schematically indicating a position of a point on item  1300 ).  FIG. 3  is a side view showing rod  1100  continuing to extend in the direction of arrow  304  with drive head  390  remaining a contracting/squeezing state thereby causing plurality of gripping inserts  490 , 590  to remain frictionally connected with item  1300 , thereby causing item  1300  to continue to turn in the direction of arrow  310  (with arrows  1310  and  1312  now schematically indicating the relative rotation of item  1300 ). In this manner, during an extension stroke of rod  1100  item,  1300  can be turned relatively (e.g., from arrow  1310  to arrow  1312 ). When rod  1100  is retracted (in the direction of arrow  304 ′), drive head  390  will enter an expanded state (schematically indicated by plurality of arrows  330  in  FIG. 4 ) allowing drive head  390  to rotatively slide relative to item  1300  in the direction as arrow  308 ′ setting up the next extension cycle for rod  1100 . In similar manner drive head  390  can ratchet back and forth over item  1300 —turning item  1300  when drive head is in a contracted/squeezing state (i.e., when rod  1100  is extending in the direction of arrow  304  with squeezing/contracting schematically indicated by plurality of arrows  328  in  FIG. 2 ), and slipping over item  1300  when drive head  390  is in an expanded state (i.e., when rod  1100  is retracting in the direction of arrow  304 ′ with expansion schematically indicated by plurality of arrows  330  in FIG.  4 )—while the drive head  390  remains closed in both the squeezing/contracted and expanded states. 
         [0067]      FIGS. 28 and 29  are schematic diagrams of the four bar linkage system for the squeezing drive head  390  shown respectively in expanded ( FIG. 28 ) and squeezed or compressed ( FIG. 29 ) states. For purposes of clarity first  400  and second  500  are shown as straight lines (instead of their actual arcuate shapes). In  FIG. 28  first section  400  and second section  500  links make an angle  396 . In  FIG. 29 , this angle is reduced to  396 ′ as pivot point  612  of fulcrum lever  600  is moved in the direction of arrow  312  (by extension of rod  1100 ) from  FIG. 28  to  FIG. 29 . Similarly, retraction of rod  1100  moves pivot point  612  of fulcrum lever  612  in the opposite direction of arrow  312 ′ in  FIG. 29  to its position shown in  FIG. 28 . Moving pivot point  612  from its position in  FIG. 28  to its position in  FIG. 29  causes first and second sections  400 , 500  to close in (Reducing angle  396  to angle  396 ′). On the other hand, moving pivot point  612  from its position shown in  FIG. 29  to its position shown in  FIG. 28  causes first and second sections  400 , 500  to open in (enlarging angle  396 ′ to angle  396 ). Such reduction and enlargement of angle  396  allows drive head  395  to clamp on and turn an item  1300  (during extension of rod  1100 ), and also unclamp and slip over (during retraction of rod  1100 ) thereby allowing drive head to ratchet back from an extended to not extended position without having to be removed from an item  1300  being turned, and without having to open up drive head  390  (i.e., drive head  390  remains a closed head during both extension and retraction of rod  1100 ). 
       Force Analysis in Drive Head 
       [0068]      FIG. 30  is a force diagram of wrench  10 . For force imposed by rod  1100  on fulcrum lever  600  at  612  is directly related to the resulting force imposed at  624 , 625  by fulcrum lever  600  on links  700 , 720  and following the following formula where: 
         [0069]    F1=the force imposed by rod  1100  on fulcrum lever  600 . 
         [0070]    F2 is the resulting force imposed at  624 , 625  on links  700 , 720 . 
         [0071]    A1 is the angle between rod  1100  and fulcrum lever  600 . 
         [0072]    A2 is the angle between fulcrum lever  600  and links  700 , 720 . 
         [0073]    D1 is the distance between opening  612  and opening  640 . 
         [0074]    D2 is the distance between openings  624 , 625  and opening  640   
         [0000]    
       
         
           
             
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         [0075]    During any one extension stroke of rod  1100 , A1 and A2 will vary. Additionally, the ratio of D1/D2 can be varied as desired by changing the lengths of fulcrum lever  600 . 
         [0076]    The amount of turning torque applied to drive head  390  is the product of F1 times the perpendicular distance from rod  1100  to the center of rotation of drive head  390  times the frictional coefficient between the drive head and item  1300 . 
         [0077]    The amount of turning torque applied by drive head  390  to item  1300  to be loosened or tightened will be equal to the average squeezing radial force applied by drive head  390  times the frictional coefficient between drive head  390  and item  1300  to be loosened or tightened. The average squeezing radial force is equal to the F2 times the perpendicular distance between F2 and pivot point  420 . 
         [0078]    In one embodiment, during an extension stroke of rod  1100 , interior space  395  of drive head  390  will attempt to contract in size. Such contraction can be caused by fulcrum lever  600  pulling on links  700 , 720  (such as in the direction of arrow  316 ) which tends to cause first link  400  to rotate relative to second link  500  in the direction of arrow  324  about pivot point  424 , 524 . 
         [0079]    In one embodiment, during a retraction stroke of rod  1100 , interior space  395  of drive head  390  will attempt to expand in size. Such expansion can be caused by fulcrum lever  600  pushing links  700 , 720  (such as in the opposite direction of arrow  316 ) which tends to cause first section  400  to rotate relative to second section  500  in the opposite direction of arrow  324  about pivot point  424 , 524 . 
       Relative Rotation of First and Second Section in Retraction Versus Extension Modes 
       [0080]    In one embodiment, during a retraction stroke of rod  1100 , the four bar linkage mechanism of drive head  390  (formed by fulcrum  600 , links  700 , 720 ; first section  400 , and second section  500  form a four bar linkage system) will enter an expanding state where rotation of first section  400  relative to second section  500  about pivot point  424 , 524  occurs in the opposite direction of arrow  324 . In one embodiment such relative expanding relative rotation between first section  400  and second section  500  is limited/restricted to a maximum extent. In one embodiment during a retraction stroke of rod  1100 , the maximum amount of relative rotation between first section  400  and second section  500  in degrees is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, and 35 degrees. In various embodiments the maximum amount of relative rotation is between about any two of the above specified relative degree measurements. In one embodiment before reaching any maximum amount of relative rotation between first section  400  and second section  500  (with respect to the four bar link system), the increasing reaction forces arising from fulcrum lever  600  attempting to expand first section  400  relative to second section  500  increase to such an extent that frictional forces between track  570  and arcuate slot  130  (along with possible frictional forces between first section  400  and/or second section  500  relative to item  1300 ) are overcome allowing drive head  390  to rotate/ratchet back into an initial starting drive position to be ready for the next extension stroke of rod  1100 . 
         [0000]    Relative Sizes of Interior Space In Retraction versus Extension Modes 
         [0081]    In one embodiment, during a retraction stroke of rod  1100 , the four bar linkage mechanism of drive head  390  (formed by fulcrum  600 , links  700 , 720 ; first section  400 , and second section  500  form a four bar linkage system) will enter an expanding state where rotation of first section  400  relative to second section  500  about pivot point  424 , 524  occurs in the opposite direction of arrow  324  and increases the interior space  395  of drive head  390  compared to the size of the interior space  395  during a retraction stroke. In one embodiment such relative expansion of interior space  395  is limited/restricted to a maximum extent. In one embodiment during a retraction stroke of rod  1100 , the maximum amount of relative expansion of interior space during an expansion stroke in percent area (compared to the cross sectional area of interior space&#39;s  395  size during extension stroke of rod  1100 ) is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, and 35 percent. In various embodiments the maximum amount of relative expansion is between about any two of the above specified relative percentages. In one embodiment before reaching any maximum amount of relative rotation between first section  400  and second section  500  (with respect to the four bar link system), the increasing reaction forces arising from fulcrum lever  600  attempting to expand first section  400  relative to second section  500  increase to such an extent that frictional forces between track  570  and arcuate slot  130  (along with possible frictional forces between first section  400  and/or second section  500  relative to item  1300 ) are overcome allowing drive head  390  to reset by rotating/ratcheting back into an initial starting drive position to be ready for the next extension stroke of rod  1100 . 
         [0082]    In one embodiment the cross sectional area of the interior space  395  can be defined by the area circumscribed by the interior portions of the first  400  and second  500  sections of the drive head  390 . Because there may be a gap between the ends  410 , 510  of the interior portions of first  400  and second  500  sections of the drive head  390  (such as when in an expanded state), the area circumscribed can be determined by extrapolating the end  410  of the interior portion of the first section  400  of the drive head  390  onto the end  500  of the interior portion of the second section  500  of the drive head  390 . As shown in  FIG. 17  such extrapolation can be by a method of curve fitting such as using standard curve fitting (e.g., the best fit curve fit  396 ) considering the shape of the interior portion of the first section  400  of the drive head  390  and the shape of the interior portion of the second section  500  of the drive head  390 . Alternatively a straight line  397  can be drawn between the ends of the interior portion of the first  400  and second  500  sections of the drive head  390 . 
       Relative Rotation of Lever Fulcrum to Drive Head in Retraction Versus Extension Modes 
       [0083]    In one embodiment, during a retraction stroke of rod  1100 , the four bar linkage mechanism of drive head  390  (formed by fulcrum  600 , links  700 , 720 ; first section  400 , and second section  500  form a four bar linkage system) will cause lever fulcrum  600  to rotate relative to drive head (and relative to pivot arm  550  of second section  500 ) causing interior area  395  of drive head to enter an expanding state, and during extension of rod  1100  lever fulcrum  600  will rotate in the opposite direction (compared to retraction of rod  1100 ) causing drive head  390  to enter a contracted state. In one embodiment the maximum sweep (relative to drive head  390 ) of lever fulcrum  600  during retraction and extension strokes of rod  1100  in degrees is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, and 35 degrees. In various embodiments the maximum amount of relative rotation of lever fulcrum  600  is between about any two of the above specified relative degree measurements. 
       Changes in Contact Area Between Drive Head and Item to be Tightened or Loosened During Extension and Retraction 
       [0084]    In one embodiment during an extension stroke of rod  1100  drive head  390  has a maximum extension stroke area of contact with item  1300 , and during a retraction stroke of rod  1100  drive head  390  has a minimum retraction stroke area of contact with item  1300 . In one embodiment the maximum extension stroke area of contact is greater than the minimum retraction stroke area of contact. In various embodiments the extension stroke maximum area of contract is at least 1.1, 1.2, 1.3, 1.4, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 times the retraction stroke minimum area of contact. In various embodiments the ratio of these to areas is between any two of the above specified ratio measurements. 
         [0085]    As shown in  FIG. 31 , in one embodiment first section  400  and/or second section  500  can include a frictionally enhancing elements  430 ,  530 . Frictionally enhancing elements  430 ,  530  can be constructed of materials having high coefficients of frictions (such as rubber) and can be relatively flexible compared to the materials from which first  400  and second  500  sections are constructed. It has been found that during an initial extension stroke of rod  1100  drive head may start to slide over item  1300  before lever fulcrum  600  can cause drive head  390  to squeeze against item  1300  enough to create large frictional forces between contracting drive head  390  and item  1300 . In this case frictional enhancing members  430  and/or  530  can be used to create initial frictional forces until fulcrum lever  600  can cause drive head  390  to create greater frictional forces between plurality of gripping inserts  490 ,  590  and item  1300 . Frictional enhancing elements  430 , 530  are preferably flexible and can be compressed relatively easily as drive head  390  closes with an extension stroke of rod  1100 . 
         [0086]    The following is a list of reference numerals: 
         [0000]    
       
         
               
             
               
               
             
               
               
             
           
               
                   
               
               
                 LIST FOR REFERENCE NUMERALS 
               
             
          
           
               
                 (Part No.) 
                 (Description) 
               
               
                   
               
             
          
           
               
                 10 
                 improved torque wrench 
               
               
                 50 
                 base 
               
               
                 100 
                 wrench body 
               
               
                 110 
                 first end 
               
               
                 120 
                 second end 
               
               
                 130 
                 arcuate slot 
               
               
                 300 
                 squeezing substantially circular head portion 
               
               
                 304 
                 arrow 
               
               
                 308 
                 arrow 
               
               
                 310 
                 arrow 
               
               
                 312 
                 arrow 
               
               
                 316 
                 arrow 
               
               
                 320 
                 arrow 
               
               
                 324 
                 arrow 
               
               
                 328 
                 arrows 
               
               
                 330 
                 arrows 
               
               
                 390 
                 drive head 
               
               
                 395 
                 interior space 
               
               
                 396 
                 first curve 
               
               
                 397 
                 line 
               
               
                 400 
                 first arcuate section 
               
               
                 410 
                 first end 
               
               
                 414 
                 opening 
               
               
                 420 
                 second end 
               
               
                 424 
                 opening 
               
               
                 430 
                 friction element 
               
               
                 450 
                 handle 
               
               
                 470 
                 fastener 
               
               
                 490 
                 plurality of gripping inserts 
               
               
                 500 
                 second arcuate section 
               
               
                 510 
                 first end 
               
               
                 520 
                 second end 
               
               
                 524 
                 opening 
               
               
                 530 
                 friction element 
               
               
                 550 
                 arm member 
               
               
                 560 
                 opening 
               
               
                 570 
                 track 
               
               
                 590 
                 plurality of gripping inserts 
               
               
                 600 
                 fulcrum lever 
               
               
                 610 
                 first end 
               
               
                 612 
                 opening 
               
               
                 620 
                 second end 
               
               
                 624 
                 prong 
               
               
                 625 
                 opening 
               
               
                 628 
                 prong 
               
               
                 629 
                 opening 
               
               
                 640 
                 opening 
               
               
                 660 
                 fastener 
               
               
                 670 
                 fastener 
               
               
                 700 
                 first link 
               
               
                 704 
                 first end 
               
               
                 708 
                 second end 
               
               
                 720 
                 second link 
               
               
                 724 
                 first end 
               
               
                 728 
                 second end 
               
               
                 750 
                 fastener 
               
               
                 760 
                 fastener 
               
               
                 762 
                 fastener 
               
               
                 1000 
                 hydraulic cylinder 
               
               
                 1010 
                 first end 
               
               
                 1020 
                 second end 
               
               
                 1030 
                 fastener 
               
               
                 1100 
                 rod 
               
               
                 1110 
                 first end 
               
               
                 1120 
                 second end 
               
               
                 1124 
                 arrows 
               
               
                 1200 
                 hydraulic line 
               
               
                 1210 
                 hydraulic line 
               
               
                 1300 
                 pipe 
               
               
                 1310 
                 arrow 
               
               
                   
               
             
          
         
       
     
         [0087]    All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. 
         [0088]    It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention set forth in the appended claims. The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.