Abstract:
A gate valve includes a gate and a drive train. The drive train includes a gate rod for linearly moving the gate, a translator operatively coupled to the gate rod for moving the gate rod linearly in response to rotational motion, and a coupling device connected to the translator for providing rotational motion. The gate valve also includes a fluid cylinder cooperatively coupled to the drive train for providing an assisting force to move the gate rod linearly and a rotary valve cooperatively connected to the coupling device and in a fluid flow path between the cylinder and a fluid pressure source. Torque applied to the coupling device moves the rotary valve to an open position to supply fluid pressure to the fluid cylinder.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates in general to valves, and in particular to valves with power assisted opening and closing. 
         [0003]    2. Description of the Prior Art 
         [0004]    It is often required that surface valves are manually operated. Significant forces may be needed to open and close gate valves, due to high friction as a result of differential pressure across the gate. Large gate valves used in the oil and gas industry in surface test trees and surface trees often require the use of handwheels and gearboxes to reduce the torque needed to manually open the valve. Alternatively remotely operated vehicles (ROVs) with torque tools may be used to open and close the valves. It would be advantageous to be able to open and close such valves by hand without using excessive force and with a minimal number of turns. 
         [0005]    Current practice is to install a valve with a fine pitch thread and a gearbox, if it is required that the valve be able to be opened and closed with minimal force exerted. However, this option would still require a great deal of strength, a large number of turns of the hand wheel and limits to the size, operating capacity and conditions of the valve. 
       SUMMARY 
       [0006]    Embodiments of this application use power assisted steering technology with a rack and rotary valve to assist the opening and closing of a valve, for example, for a gate valve in a surface tree. The output from the rotary valve rotates a valve stem and coupling. 
         [0007]    In an embodiment of the current application, a gate valve includes a gate and a drive train. The drive train includes a gate rod for linearly moving the gate, a translator operatively coupled to the gate rod for moving the gate rod linearly in response to rotational motion, and a coupling device connected to the translator for providing rotational motion. The gate valve also includes a fluid cylinder cooperatively coupled to the drive train for providing an assisting force to move the gate rod linearly and a rotary valve cooperatively connected to the coupling device and in a fluid flow path between the cylinder and a fluid pressure source. Torque applied to the coupling device moves the rotary valve to an open position to supply fluid pressure to the fluid cylinder. 
         [0008]    In alternative embodiments, the coupling device includes input and output couplings that are rotationally moveable relative to each other a fractional amount so that the rotation relative to each other causes the rotary valve to move to the open command position. A torsion bar may be disposed between the input coupling and the output coupling to prevent rotational movement between the input coupling and the output coupling until sufficient torque is applied to the input coupling to cause deformation of the torsion bar. The gate valve may include drive dogs mechanically connected between the input coupling and the output coupling that cause rotation in unison after the fractional amount has been reached. 
         [0009]    The translator may include a nut rod with external threads on an outer surface, a tubular drive with an internal bore, and a travel nut retained within the internal bore of the tubular drive, the travel nut comprising internal threads which engage the external threads of the nut rod, so that rotation of the coupling device causes axial movement of the gate rod. 
         [0010]    The cylinder may have an internal cavity comprising a nut end compartment and a gate end compartment. In some embodiments, the gate valve further includes a piston located within the cylinder, the piston separating the nut end compartment from the gate end compartment, so that a pressure differential between the nut end compartment and the gate end compartment will encourage the gate to move between the open and a closed position. An open port may be located in a side wall of the nut end compartment for supplying hydraulic fluid to and from the nut end compartment of the cylinder. A close port may be located in a side wall of the gate end compartment of the cylinder for supplying hydraulic fluid to and from the gate end compartment of the cylinder. 
         [0011]    In other embodiments, the gate valve may include a sleeve with a central bore, a cylindrical inner member rotatable within the sleeve to a fractional amount, an open port and a close port in the sleeve spaced circumferentially apart, a supply void on the inner member extending circumferentially and an input port in the sleeve between the open and close ports to supply hydraulic fluid to the supply void. Rotation of the inner member relative to the sleeve in the first direction provides unequal communication between the open and close ports and the supply void. The circumferential extension of the supply void may be less than the circumferential distance between the open and close ports. Rotation of the inner member relative to the sleeve to the fractional amount in the first direction may block fluid communication between the close port and the supply void and provides fluid communication between the open port and the supply void. There may be a return port on the sleeve and a return void extending circumferentially on the inner member in fluid communication with the return port. Rotation of the inner member relative to the sleeve in the first direction blocks fluid communication between the open port and the return void and provides fluid communication between the close port and the return void. 
         [0012]    In other embodiments of the current application, a method for assisting in the operation of a gate valve having a linearly moveable gate includes (a) coupling a piston rod of a bi-directional hydraulic cylinder to the gate; (b) connecting a rotary to linear translator to the piston rod; (c) connecting an input coupling to the translator and providing the input coupling with a rotary valve that is connected between a hydraulic fluid source and the hydraulic cylinder; and (d) rotating the input coupling in a first direction which causes the translator to move the piston rod and gate to an open position. The rotation in step (d) also causing the rotary valve to direct fluid from the source to the cylinder to create an open assisting force on the piston rod. Rotating the input coupling in a second direction may cause the translator to move the piston rod and gate to a closed position and the rotary valve to direct fluid from the source to the cylinder to create a close assisting force on the piston rod. 
         [0013]    The rotary valve may have open command ports and close command ports, and the step of rotating the input coupling in a first direction may communicate the open command port with the source and restrict the close command ports from the source. The assisting force provided by the cylinder may be proportional to an amount of torque imposed on the input coupling. 
         [0014]    The input coupling may have an input portion and an output portion and step (d) initially causes the input portion to rotate a fractional amount relative to the output portion. The fractional amount of relative rotation may cause rotation of one component of the rotary valve relative to another component of the valve. After reaching the fractional amount, continued rotation of the input coupling may cause the input portion and output portion to rotate in unison. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    So that the manner in which the above-recited features, aspects and advantages of the invention, as well as others that will become apparent, are attained and can be understood in detail, a more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof that are illustrated in the drawings that form a part of this specification. It is to be noted, however, that the appended drawings illustrate only preferred embodiments of the invention and are, therefore, not to be considered limiting of the invention&#39;s scope, for the invention may admit to other equally effective embodiments. 
           [0016]      FIG. 1  is a sectional view of a power assisted system of an embodiment of the current application. 
           [0017]      FIG. 2A  is a sectional view of a drive nut assembly portion of the power assisted system of  FIG. 1 . 
           [0018]      FIG. 2B  is a cross sectional view of a travel nut of the power assisted system of  FIG. 2A  taken along the line  2 B- 2 B of  FIG. 2A . 
           [0019]      FIG. 3A  is a sectional view of a valve drive system of the power assisted system of  FIG. 1 . 
           [0020]      FIG. 3B  is a partial sectional view of a dog and dog recess of the power assisted system of  FIG. 3A  taken along the line  3 B- 3 B of  FIG. 3A . 
           [0021]      FIG. 3C  is a cross sectional view of the valve drive system of the power assisted system of  FIG. 3A  in a neutral position, taken along line  3 C- 3 C of  FIG. 3A . 
           [0022]      FIG. 3D  is a cross sectional view of the valve drive system of the power assisted system of  FIG. 3A  similar to  FIG. 3C , but with the system in an open position. 
           [0023]      FIG. 3E  is a cross sectional view of the valve drive system of the power assisted system of  FIG. 3A , similar to  FIG. 3C , but with the system in a close position. 
           [0024]      FIG. 4  is a schematic view of the hydraulic system of the power assisted system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Referring to  FIG. 1 , a power assisted valve system  10  of an embodiment of the current application is shown to include a valve member, which may be, for example, gate  12 , which moves along a central axis  14  of system  10 . A gate opening  16  through gate  12  will be in fluid communication with valve bore  18  when the gate  12  is in an open position and will block the flow of fluid through valve bore  18  when gate  12  is in a closed position. In alternative embodiments, valve system  10  may instead include alternative valve types that utilize axial movement to open and close. 
         [0026]    One end of output rod, or gate rod  20  is connected to an end of gate  12 . The other end of gate rod  20  is securely fastened to a piston  22  within cylinder  24 . Cylinder  24  is a tubular member with an internal cavity that contains piston  22 . A piston  22  is reciprocally carried within cylinder  24 , defining a chamber  28  between gate side  30  of piston  22  and gate end  32  of cylinder  24 . As piston  22  moves along axes  14  of system  10  within cylinder  24 , gate rod  20  also moves along axis  14  of system  10 , causing gate  12  to also move along axis  14  of system  10  between open and closed positions. When piston  22  moves axially away from gate end  32  of cylinder  24  and towards nut end  34  of cylinder  24 , gate  12  moves to a closed position. Conversely, when piston  22  moves axially away from nut end  34  of cylinder  24  and towards gate end  32  of cylinder  24 , gate  12  moves to an open position. 
         [0027]    A hydraulic pumping system will manage the flow of hydraulic fluids through hydraulic open port  36  and hydraulic close port  38  to create differential pressure between the nut side  40  and gate side  30  of piston  22  to urge piston  22  to move axially towards gate end  32  of cylinder  24  and gate  12  to move to an open position. This may occur, for example, by injecting hydraulic fluid into hydraulic open port  36 , removing hydraulic fluid through hydraulic close port  38 , or some combination thereof. 
         [0028]    Hydraulic fluid pumped into hydraulic open port  36  is contained within a nut end compartment  42  which is defined by the interior wall of cylinder  24 , the nut side  40  of piston  22  and nut end  34  of cylinder  24 . Pumping hydraulic fluid into open port  36  will urge piston  22  to move axially away from nut end  34  of cylinder  24  and towards gate end  32  of cylinder  24  such that gate  12  moves towards an open position. 
         [0029]    Hydraulic fluid pumped into hydraulic close port  38  is contained within gate end compartment  28 . A ring seal  44  is located between piston  22  and the interior wall of cylinder  24 , sealing nut end compartment  42  from fluid communication with gate end compartment  28 . Pumping hydraulic fluid into close port  38  will cause piston  22  to move axially away form gate end  32  of cylinder  24  and towards nut end  34  of cylinder  24  such that gate  12  moves towards a closed position. 
         [0030]    A mechanical device is used to cause piston  22  to move axially within cylinder  24 , and the hydraulic system assists in the movement. The mechanical device includes a square drive  46  located at a nut end of valve system  10 . Square drive  46  is a solid elongated member which may have a square, polygonal, or other geometric cross section. When square drive  46  is rotated, it causes a drive coupling  48 , to rotate. Drive coupling  48  is a tubular member with a bore  52 . Drive nut assembly  53 , as can be seen in more detail in  FIG. 2A , has a travel nut  50  secured within bore  52  of drive coupling  48 . In this example, travel nut  50  is fixed within bore  52  such that it cannot move axially or rotationally relative to drive coupling  48 . Internal bore  52  may be hexagonal in cross section, as can be seen in  FIG. 2B . In such an embodiment, the external shape of travel nut  50  will mate with and engage the hexagonal cross section of internal bore  52  so that relative rotational movement between travel nut  50  and internal bore  52  is limited. Travel nut  50  has internal threads  54  which engage external threads  56  located on an outer surface of an input rod, or nut rod  58  in proximity to a drive end of a nut rod  58 . 
         [0031]    Returning to  FIG. 1 , the other end of nut rod  58  is connected to piston  22 . As drive coupling  48  rotates, travel nut  50  will also rotate, but nut rod  58  does not rotate. Instead, the internal threads  54  engage external threads  56  ( FIG. 2B ), causing axial movement of nut rod  58 , which in turn causes piston  22  to move axially within cylinder  24  ( FIG. 1 ). Therefore, when square drive  46  is rotated, piston  22  will either move axially away from gate end  32  of cylinder  24  and towards nut end  34  of cylinder  24 , causing gate  12  to move to a closed position; or conversely, piston  22  will move axially away from nut end  34  of cylinder  24  and towards gate end  32  of cylinder  24 , causing gate  12  to move to an open position. Drive nut assembly  53  therefore acts as a translator to convert rotary motion of square drive  46  to linear movement of gate  12 . 
         [0032]    In situations where it is desirable for an operator to manually open and close gate  12 , embodiments of the current application also provide a means for hydraulically assisting the operator to do so. Turning to  FIG. 3A , in such an embodiment, square drive  46  may be fitted with a hand wheel. Square drive  46  is connected to a drive end of input coupling  60 . The opposite end of input coupling  60  houses a torsion bar  62  and drive dogs  64 . Both the torsion bar  62  and dogs  64  mate with output coupling  66 . Torsion bar  62  may be a solid length of metal, elastomeric or other material with elastic properties, with a square or other geometric shaped cross section. One end of torsion bar  62  is located within a recess in an end of input coupling  60 , which has a similar shaped and sized cross section to the cross section of torsion bar  62 . Similarly, the other end of torsion bar  62  is located within a recess of output coupling  66  which has a similar shaped and sized cross section to the cross section of torsion bar  62 . 
         [0033]    Output coupling  66  comprises a cylindrical tubular section  67  with a bore  68  and a solid stem section  70 . Input coupling  60  is located within the bore  68  of output coupling  66 . Stem section  70  of output coupling  66  is secured to drive coupling  48  in a manner which prevents relative rotation movement between output coupling  66  and drive coupling  48 . For example, an end of stem section  70  may be located within bore  52  of drive coupling  48  and stem section  70  may be bolted to drive coupling  48 . Therefore the valve drive system  77  comprises an input coupling  60 , output coupling  66 , housing  72  and base plate  76 . 
         [0034]    When no forces are being applied to valve system  10  to open or close gate  12 , torsion bar  62  maintains the relative rotational alignment between the input coupling  60  and the output coupling  66 . As square drive  46  is rotated, input coupling  60  rotates. If sufficient force is applied to input coupling  60 , torsion bar  62  will undergo elastic deformation and allow for relative rotational movement between input coupling  60  and output coupling  66 . 
         [0035]    Dogs  64  may be solid members that protrude from the bottom of bore  68  of output coupling  66  and engage dog recesses  65  in the end of input coupling  60 . Dogs may be formed of metal or other suitable material. As seen in  FIG. 3B , dogs  64  have sufficient clearance within recesses  65  to allow for a fractional amount of relative rotational movement between input coupling  60  and output coupling  66 , but not so much clearance to allow the torsion bar  62  to shear. The fractional amount of relative rotational movement will be sufficient to generate the open and close fluid flow paths as discussed in more detail herein. When the square drive  46  is rotated, after such clearance is overcome, dogs  64  will engage an interior side wall of recess  65  and will transmit the rotation of input coupling  60  to rotation of output coupling  66 , causing drive coupling  48 , to rotate and gate  12  to move towards either an open or closed position. 
         [0036]    A housing  72  surrounds the tubular section  67  of output coupling  66 . Housing  72  is a generally cylindrical member with an internal cavity  74 . Internal cavity  74  is open at a drive end and has a closure  79  at the other end. The tubular section  67  of output coupling  66  is located within internal cavity  74 . The open drive end of housing  72  is secured to a base plate  76 , which is stationary. For example, housing  72  may be bolted to base plate  76 . Closure  79  has an opening through which the stem  70  of output coupling  66  protrudes. Bottom seal  78  is disposed between output coupling  66  and housing  72 , sealingly engaging both the output coupling  66  and housing  72 , creating a seal between output coupling  66  and housing  72 . Cylindrical bearing element  80  maintains a coaxial relationship between output coupling  66  and housing  72 . 
         [0037]    Housing  72  includes ports  82 ,  84 ,  86 ,  88  which pass though a side wall of housing  72 . The valve drive system  77  includes a supply hydraulic fluid flow path. Housing supply port  86  is axially aligned with output supply port  90 , which passes through a side wall of the tubular section  67  of output coupling  66 . If housing supply port  86  is not rotationally aligned with output supply port  90 , an annular supply or gallery groove  92  within internal cavity  74  of housing  72  will allow for fluid communication between housing supply port  86  and output supply port  90 . Supply groove  92  has a width that is substantially similar to that of the diameter of both housing supply port  86  and output supply port  90  ( FIG. 3A ). Ports  82 ,  84  are spaced apart from each other along the axis of output coupling  66 , as shown in  FIG. 3A . Although illustrated in  FIG. 3C  as being at different circumferential locations relative to housing supply port  86 , ports  82 ,  84  may be axially aligned with housing supply port  86 . 
         [0038]    As shown in  FIG. 3C , housing open port  82  and housing close port  84  optionally may be aligned with an output open port  94  and output close port  96 , respectively, extending through the side wall of output coupling  66 . Output open port  94  and output close port  96  are spaced circumferentially apart from each other, such as about 80°. If housing open port  82  is not rotationally aligned with output open port  94 , an annular open gallery groove  98  within internal cavity  74  of housing  72  will allow for fluid communication between housing open port  82  and output open port  94 . Open groove  98  has a width that is substantially similar to that of the diameter of both housing open port  82  and output open port  94 . If housing close port  84  is not rotationally aligned with output close port  96 , an annular close gallery groove  100  within internal cavity  74  of housing  72  will allow for fluid communication between housing close port  84  and output close port  96 . Close groove  100  has a length that is substantially similar to that of the length of both housing close port  84  and output close port  96 . 
         [0039]    The valve drive system  77  additionally includes a return hydraulic fluid flow path. Housing return port  88  is axially aligned with output return port. If housing return port  88  is not rotationally aligned with output return port  102 , an annular return gallery groove  104  within internal cavity  74  of housing  72  will allow for fluid communication between housing return port  88  and output return port  102 . Return groove  104  has a width that is substantially similar to that of the diameter of both housing return port  88  and output return port  102 . 
         [0040]    A supply void  106  is located on the outer surface of the input coupling  60 . It is a shallow recess located axially beneath output supply port  90 . As shown in  FIG. 3C , the circumferentially extending width of supply void  106  is such that when no mechanical forces are being applied to valve system  10  to open or close gate  12 , the supply void  106  extends to, but not beyond, a near edge of output open port  94  and output close port  96 . The circumferential width of supply void  106  is approximately the circumferential distance between the edges of output open port  94  and output close port  96 . The length of supply void  106  is such that it extends axially from the housing open port  82  to the housing close port  84 , but does not reach the housing return port  88 . 
         [0041]    A return void  108  is located on the outer surface of the input coupling  60 . It is a shallow recess located on the opposite side of input coupling  60  as supply void  106 . The width of return void  108  is such that when no forces are being applied to valve system  10  to open or close gate  12 , the return void  108  extends to, but not beyond a near edge of both the output open port  94  and output close port  96 . The length of return void  108  is such that it extends axially from the housing open port  82  to the housing return port  88 . 
         [0042]    Turning now to  FIG. 4 , a hydraulic system  110  includes a pump  112  for supplying hydraulic fluids to output supply port  90 . Hydraulic fluids can be drawn from a reservoir  114  which contains hydraulic fluids that exit through output return port  102 . Open hydraulic flow line  116  fluidly connects output open port  94  and open port  36  in cylinder  24 , which is in fluid communication with nut end compartment  42  of cylinder  24 . Close hydraulic flow line  120  fluidly connects output close port  96  and close port  38 , in cylinder  24 , which is in fluid communication with gate end compartment  28  of cylinder  24 . Returning to  FIG. 3A , a secondary return port  126  is in fluid communication with return void  108 . Secondary return port  126  extends through an opposite side wall of the tubular section  67  of output coupling  66  than output return port  102  and is axially aligned with output return port  102 . 
         [0043]    In operation, when no rotational forces are being applied to valve system  10  to open or close gate  12 , hydraulic fluid traveling into housing supply port  86  ( FIG. 3A ) will flow through output supply port  90 , either directly, if supply ports  86 ,  90  are rotationally aligned, or by way of annular supply groove  92  if they are not. As seen in  FIG. 3C , hydraulic fluid passing through output supply port  90  will enter supply void  106 . Torsion bar  62  maintains the rotational alignment of input coupling  60  and output coupling  66  such that no hydraulic fluid enters output open or close ports  94 ,  96 . In alternative embodiments, torsion bar  62  maintains the rotational alignment of input coupling  60  and output coupling  66  such that equal amounts of hydraulic fluid enter output open and close ports  94 ,  96 . Therefore a supply flow path of the valve drive system  77  will include housing supply port  86 , annular supply groove  92 , output supply port  90 , and supply void  106 . 
         [0044]    As seen in  FIG. 4 , the hydraulic fluid may then be contained in reservoir  114  for continued use by hydraulic system  110 . Therefore a return flow path of the valve drive system  77  will include return void  108 , secondary return port  126 , annular return groove  104 , and housing return port  88 . 
         [0045]    If an operator wishes to open or close the valve, the operator rotates square drive  46 . In the embodiment of  FIG. 3A , a counterclockwise rotation will open the valve and a clockwise rotation will close the valve. Torsion bar  62  will twist and allow for some relative rotational movement between input coupling  60  and output coupling  66 . As input coupling  60  rotates relative to output coupling  66 , supply void  106  located on output coupling  66  will rotate relative to the output open and close ports  94 ,  96 . 
         [0046]    Therefore, as seen in  FIGS. 3A and 3D , the rotation of square drive  46  in a counterclockwise motion will cause the valve drive system  77  to move to an open command position. Counterclockwise rotation of square drive  46  will cause supply void  106  to rotate counterclockwise relative to output ports  90 ,  94 ,  96  such that supply void  106  will rotate counterclockwise relative to output coupling  66  so that the circumferential length of supply void  106  will be in fluid communication with both output supply port  90  and output open port  94  but not output close port  96 . Again, hydraulic fluid is pumped by pump  112  ( FIG. 4 ) into housing supply port  86  will travel through output supply port  90 , either directly if the supply ports  86 ,  90  are rotationally aligned or by way of annular supply groove  92  if they are not, and reach supply void  106 . 
         [0047]    In this case, some of the hydraulic fluid in supply void  106  will travel into output open port  94  and into housing open port  82 , either directly if the open ports  82 ,  94  are rotationally aligned, or by way of annular open groove  98 . As seen in  FIG. 4 , hydraulic fluid will then travel through open hydraulic flow line  116  to open port  36  and enter nut end compartment  42  of cylinder  24 . The extra hydraulic pressure in nut end compartment  42  of cylinder  24  will encourage piston  22  to move axially away from nut end  34  of cylinder  24  and towards gate end  32  of cylinder  24  such that gate  12  ( FIG. 1 ) moves towards an open position. Therefore the open flow path of the valve drive system  77  will include supply void  106 , output open port  94 , annular open groove  98 , and housing open port  82  and rotating square drive  46  can activate, or select, the open flow path of valve drive system  77 . 
         [0048]    In this manner, as an operator rotates square drive  46 , the hydraulic system ( FIG. 4 ) will assist with the opening of the valve so that the operator himself does not have to apply all of the force to square drive  46  to overcome all of the forces required to move gate  12  to an open position. In the event the hydraulic system failed, as the operator rotates square drive  46 , after the clearance of the dogs  64  between input coupling  60  and output coupling  66  is overcome, dogs  64  engage the side walls of recess  65  ( FIG. 3B ) and will mechanically transmit the rotation of input coupling  60  to rotation of output coupling  66 , causing drive coupling  48  to rotate. As seen in  FIG. 2A , as drive coupling  48  rotates, travel nut  50  rotates and the internal threads  54  of travel nut  50  engage the external threads  56  of nut rod  58 . This causes axial movement of nut rod  58  which in turn causes gate  12  to move to an open position. 
         [0049]    Therefore both the continued rotation of square drive  46  and the hydraulic system  110  are working to move the gate  12  to an open position. In order for the hydraulic system  110  to provide assistance, the operator only needs to apply sufficient force to cause supply void  106  to rotate counterclockwise relative to output ports  90 ,  94 . The greater the torque applied to square drive  46 , the greater the relative rotation between void  106  and output ports  90 ,  94 , causing more hydraulic fluid to be directed into the output open port  94  and providing more assistance to the operator e in moving gate  12  to an open position. 
         [0050]    As piston  22  moves towards gate end  32  of cylinder  24 , hydraulic fluid in gate end compartment  28  will be forced out close port  38 , through close hydraulic flow line  120  and into output close port  96 . Returning to  FIGS. 3A and 3D , hydraulic fluid will reach output close port  96  either directly from housing close port  84 , if close ports  84 ,  96  are rotationally aligned, or by way of annular close groove  100  if they are not. Because input coupling  60  has rotated counterclockwise relative to output coupling  66 , return void  108  is now in fluid communication with output close port  96 . Hydraulic fluid can therefore travel from output close port  96  and into return void  108  where it then pass though secondary return port  126  through annular return groove  104  and exit the housing  72  though housing return port  88 . As seen in  FIG. 4 , the hydraulic fluid may then be contained in holding tank  114  for continued use by hydraulic system  110 . 
         [0051]    If the operator desires to move gate  12  towards a closed position, the operator would instead rotate square drive  46  in a clockwise motion. Looking at  FIG. 3A  and  FIG. 3E , the rotation of square drive  46  in a clockwise motion will cause the valve drive system  77  to move to a closed command position. Rotation of square drive  46  in a clockwise motion will cause supply void  106  to rotate clockwise relative to output ports  90 ,  94 ,  96  such that supply void  106  will be in fluid communication with both output supply port  90  and output close port  96  but not output open port  94 . Again, hydraulic fluid is pumped by pump  112  ( FIG. 4 ) into housing supply port  86  will travel through output supply port  90 , either directly if the supply ports  86 ,  90  are rotationally aligned or by way of annular supply groove  92  if they are not, and reach supply void  106 . 
         [0052]    In this case, some of the hydraulic fluid in supply void  106  will travel into output close port  96  and into housing close port  84 , either directly if the close ports  84 ,  96  are rotationally aligned, or by way of annular close groove  100 . As seen in  FIG. 4 , hydraulic fluid will then travel through close hydraulic flow line  120  to close port  38  and enter gate end compartment  28  of cylinder  24 . The extra hydraulic pressure in gate end compartment  28  of cylinder  24  will encourage piston  22  to move axially towards nut end  34  of cylinder  24  and away from gate end  32  of cylinder  24  such that gate  12  ( FIG. 1 ) moves towards an closed position. Therefore the close flow path of the valve drive system  77  will include supply void  106 , output close port  96 , annular close groove  100 , and housing close port  84  and rotating square drive  46  can activate, or select, the close flow path of valve drive system  77 . 
         [0053]    In this manner, as an operator rotates square drive  46  in a clockwise motion, the hydraulic system ( FIG. 4 ) will assist with the closing of the valve so that the operator himself does not have to apply all of the force to square drive  46  to overcome all of the forces required to move gate  12  to a closed position. Returning to  FIG. 1 , as the operator rotates square drive  46 , after the clearance of the dogs  64  between input coupling  60  and output coupling  66  is overcome, dogs  64  will be engaged and will transmit the rotation of rotation of input coupling  60  to rotation of output coupling  66 , causing drive coupling  48  to rotate. As seen in  FIG. 2A , as drive coupling  48  rotates, travel nut  50  rotates and the internal threads  54  of travel nut  50  engage the external threads  56  of nut rod  58 . This causes axial movement of nut rod  58  which in turn causes gate  12  to move to a closed position. 
         [0054]    Therefore both the continued rotation of square drive  46  and the hydraulic system  110  are working to move the gate  12  to a closed position. In order for the hydraulic system  110  to provide assistance, the operator only needs to apply sufficient force to cause supply void  106  to rotate clockwise relative to output ports  90 ,  96  and the greater the torque applied to square drive  46 , the greater the relative rotation between void  106  and output ports  90 ,  96 , the more hydraulic fluid will be directed into the output close port  96  and the more assistance the operator will receive in moving gate  12  to a closed position. 
         [0055]    As piston  22  moves towards nut end  34  of cylinder  24 , hydraulic fluid in nut end compartment  42  will be forced out open port  36 , through open hydraulic flow line  116  and into output open port  94 . Returning to  FIGS. 3A and 3E , hydraulic fluid will reach output open port  94  either directly from housing open port  82 , if open ports  82 ,  94  are rotationally aligned, or by way of annular open groove  98  if they are not. Because input coupling  60  has rotated clockwise relative to output coupling  66 , return void  108  is now in fluid communication with output open port  94 . Hydraulic fluid can therefore travel from output open port  94  and into return void  108  where it then pass though secondary return port  126  through annular return groove  104  and exit the housing  72  though housing return port  88 . As seen in  FIG. 4 , the hydraulic fluid may then be contained in reservoir  114  for continued use by hydraulic system  110 . 
         [0056]    In order to maintain the open, close, supply and return hydraulic flow paths fluidly separated from each other, separations seals  128  are located between the outer diameter of tubular section  67  of output coupling  66  and the internal cavity  74  of housing  72 . Separation seals are annular seals and are situated on both sides of each of the housing ports  82 ,  84 ,  86 ,  88 . Additional bottom seals are located in the output coupling bore  68  at the junction of the tubular section  67  and stem of output coupling  66  and are in sealing engagement with both output coupling  66  and input coupling  60 . At the open end of the tubular section  67  of output coupling  66 , bearing elements  132  and  134  maintain a coaxial relationship between input coupling  60 , output coupling  66  and housing  77 . At the closed end of the tubular section bearing element  79  maintains a coaxial relationship between the input coupling  60  and the output coupling  66 . 
         [0057]    Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the invention. Accordingly, the scope of the present invention should be determined by the following claims and their appropriate legal equivalents. 
         [0058]    The singular forms “a” “an” and “the” include plural referents, unless the context clearly dictates otherwise. Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur. Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range. 
         [0059]    Throughout this application, where patents or publications are referenced, the disclosures of these references in their entireties are intended to be incorporated by reference into this application, in order to more fully describe the state of the art to which the invention pertains, except when these reference contradict the statements made herein.