Abstract:
The present invention relates to an apparatus for use in field servicing a choke valve system. The apparatus is used for lifting, manipulating, and handling the heavy components of hydraulic choke valves. The apparatus includes an elongated track, a choke valve support structure, a trolley that selectably reciprocates along a length of the trolley, and an attachment mechanism for attaching a choke actuator to the trolley.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of pending U.S. patent application Ser. No. 10/832,779 (Attorney Docket Number PC-P006US) filed Apr. 27, 2004 by Robert F. Schmidt, et al. and entitled “Manipulator System for Servicing a Hydraulic Choke,” which claims priority to provisional U.S. Patent Application Ser. No. 60/508,177 filed Oct. 2, 2003 by Robert F. Schmidt, et al. and entitled “Manipulator System for Servicing a Hydraulic Choke.” 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an apparatus for use in servicing hardware used in the drilling and production of fluids from petroleum wells. More particularly, the present invention relates to a field servicing apparatus for lifting, manipulating, and handling the heavy components of hydraulic choke valves.  
         [0004]     2. Description of the Related Art  
         [0005]     Hydraulic choke devices are commonly used in the oilfield when drilling or treating wells. Herein, the term “hydraulic choke” is taken to refer to a device typically used as a pressure reducing valve with a variety of fluids, such as drilling mud, salt water, oil, gas, and other chemicals that are injected into or withdrawn from a well. “Hydraulic” does not herein refer to the choke actuation means. The service conditions for hydraulic chokes are typically severe, so that the units require frequent field servicing in order to minimize drilling or production downtime. Since the primary components of the choke system, namely the choke valve itself and its associated actuator, are very heavy and field working conditions are often difficult for handling the choke valve, an auxiliary manipulation means is needed to ease choke servicing.  
         [0006]     Manipulator devices are use for simplifying the servicing of blowout preventers. However, easy-to-use manipulators for hydraulic choke valves have not been available previously.  
         [0007]     Kunkle, U.S. Pat. No. 4,460,154, discloses a pair of telescoping tubes supported in a fixed relationship to a valve. One tube provides a mounting location for a linear actuator, while the other tube is stationary.  
         [0008]     Hewitt, U.S. Pat. No. 4,961,538, discloses a valve operation system wherein a linear actuator is provided with a rod in a housing. The system components are held in place by a mounting plate that may be secured to a number of different valves through a valve stem adaptor.  
         [0009]     Hewitt, in U.S. Pat. No. 4,611,617, discloses an apparatus mountable on an irrigation pipe for use in controlling valves within the pipe. The apparatus includes a mounting bracket attachable to the valve mechanism and mounting plates for various components of a drive mechanism, including an electric motor, a gear box, a main gear, and a drive chain.  
         [0010]     None of these references disclose equipment that will simplify the lifting and manipulation of the heavy components of a choke valve. Power Chokes of Cypress, Texas has used a primitive manipulator for choke valves based on horizontally telescoping support tubes, wherein one tube is mounted to the body of the choke valve and the other tube has its end attached to the separable actuator of the choke valve. The first tube is able to pivot about a nominally vertical axis to permit adjusting the actuator alignment relative to the choke valve. However, this apparatus requires that the tubes remain in the horizontal plane so that high side loads do not cause inadvertent misalignment. Further stick-slip motion of this Power Chokes actuator made manipulation difficult.  
         [0011]     A need exists for a simple to install, robust field service device for hydraulic choke valves which is insensitive to stick-slip behavior and misalignment.  
       SUMMARY OF THE INVENTION  
       [0012]     The invention contemplates a choke valve manipulator device comprising: a frame; a mounting means for attaching a choke valve to the frame; and a rotation means for rotating the choke valve about an axis of a horizontal plane; whereby the manipulator device supports the weight of the choke valve and eases access to the choke valve components whenever the choke valve is serviced.  
         [0013]     The invention further contemplates a choke manipulator device comprising: a frame; a mounting means for attaching a choke valve to the frame; and a tilt means for tilting the choke valve in a vertical plane; whereby the manipulator device supports the weight of the choke valve and eases access to the choke valve components whenever the choke valve is serviced.  
         [0014]     Additionally, the invention contemplates a choke manipulator device comprising: a frame having an elongated track; a choke valve attachment structure positioned on an underside of the track; a reciprocable trolley, wherein the trolley moves along a length of the track; a trolley actuator in communication with the trolley, the trolley actuator causing the trolley to move along the length of the track; and a choke actuator attachment mechanism positioned on an underside of the trolley; whereby when the trolley is moved the choke actuator attachment is moved in the same direction.  
         [0015]     Further, the invention contemplates a choke manipulator device comprising: a frame having an elongated track including two parallel mirror image channels; a choke valve attachment structure positioned on an underside of the track, the choke valve attachment structure rotatable about an axis of a horizontal plane; a reciprocable trolley having a plurality of mounted rollers, the rollers maintaining the trolley with the track; a trolley actuator in communication with the trolley, the trolley actuator causing the trolley to selectably reciprocate along a length of the track; and a choke actuator attachment mechanism positioned on an underside of the trolley; whereby whenever the trolley actuator moves the trolley the choke actuator attachment mechanism moves in the same direction as the trolley.  
         [0016]     In addition, the invention contemplates a method for servicing a choke valve system, said method comprising the steps of: (i) positioning a choke valve manipulation device close to the choke valve system to be serviced, the choke valve manipulation device comprising: a frame having an elongated track, a choke valve attachment structure positioned on an underside of the track, a reciprocable trolley, wherein the trolley moves along a length of the track, a trolley actuator in communication with the trolley, the trolley actuator causing the trolley to move along the length of the track, and a choke actuator attachment mechanism positioned on an underside of the trolley; (ii) attaching a choke valve to the choke valve attachment structure; (iii) aligning the choke actuator attachment mechanism with a choke actuator connected to the choke valve; (iv) attaching the choke actuator to the choke actuator attachment mechanism; (v) disconnecting the choke actuator from the choke valve; (vi) activating the trolley actuator to cause the trolley to move away from the choke valve to separate the choke valve from the choke actuator; and (v) evaluating an interior component of the choke valve system for replacement or repair.  
         [0017]     The foregoing has outlined rather broadly several aspects of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed might be readily utilized as a basis for modifying or redesigning the structures for carrying out the same purposes as the invention. It should be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:  
         [0019]      FIG. 1  is a profile view of the first manipulator embodiment assembled onto a choke valve assembly;  
         [0020]      FIG. 2  is an oblique view from above and to the side of the first manipulator embodiment corresponding to  FIG. 1 ;  
         [0021]      FIG. 3  is a longitudinal centerline cross-sectional view of the first embodiment of the manipulator assembly corresponding to  FIG. 1 ;  
         [0022]      FIG. 4  is an oblique view of the trolley subassembly of the first embodiment from above and to the side;  
         [0023]      FIG. 5  is a side profile view of the trolley subassembly of  FIG. 4 ;  
         [0024]      FIG. 6  is a plan view of the trolley subassembly of  FIG. 4 ;  
         [0025]      FIG. 7  is a longitudinal centerline cross-sectional view of the first embodiment of the manipulator assembly corresponding to  FIG. 1  and showing the choke actuator separated from the choke valve body and supported by the trolley;  
         [0026]      FIG. 8  is an oblique view from the rear quarter of the second manipulator embodiment assembled onto a choke valve assembly;  
         [0027]      FIG. 9  is a profile view of the second manipulator embodiment shown in  FIG. 8  assembled onto a choke valve assembly;  
         [0028]      FIG. 10  is an oblique exploded view of the second manipulator embodiment wherein the relatively rotatable components are displaced from each other for exposure of their working mechanisms;  
         [0029]      FIG. 11  is an oblique view of the trolley of the second manipulator embodiment; and  
         [0030]      FIG. 12  is a profile view of the second manipulator embodiment shown in  FIG. 9 , with the trolley and the disconnected actuator displaced from the choke in the axial direction. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]     The present invention provides a device for manipulating choke valve components during field service. The described manipulator is easily installed in the field and permits the easy and safe disassembly and reassembly of the choke valve components.  
         [0032]     Referring now to the drawings, and initially to  FIG. 1 , it is pointed out that like reference characters designate like or similar parts throughout the drawings. The Figures, or drawings, are not intended to be to scale. For example, purely for the sake of greater clarity in the drawings, wall thickness and spacing are not dimensioned as they actually exist in the assembled embodiment.  
         [0033]     Typical materials of construction of the choke valve manipulator are high strength low alloy steel or mild steel. In the case of plain bearings, bronze or a lubricious plastic such as Delrin™ or Teflon™, is generally used. FIGS.  1  to  7  illustrate a first embodiment  10  of a choke valve manipulator system.  
         [0034]      FIG. 1  shows the choke valve manipulator system  10  assembled to the choke valve  201  and an adjoined electrically/manually powered actuator  203 . The trolley subassembly  39  of the manipulator system  10  is shown in more detail in  FIGS. 4, 5 , and  6 .  FIG. 7  shows the manipulator of the first embodiment supporting the choke actuator, where the actuator 203  has been separated from the choke valve body  201 .  
         [0035]     Referring to FIGS.  1  to  3 , the basic manipulator assembly  10  is shown in, respectively, profile, oblique, and longitudinal vertical cross-sectional views. The major components of the manipulator assembly include the track  11 , the trolley subassembly  39  composed of a first trolley  40  and second trolley  60 , and the supporting means for the manipulator including members  90 ,  91 , and  92 .  
         [0036]     The track  11  is composed of two horizontal mirror image channels. The righthand channel  12  and the lefthand channel  13  have an extended linear section with a distal 90° arcuate curved end segment and vertical webs. To strengthen the track  11  in order to support the heavy loadings on the track, vertical flat plate stiffeners  14  are welded to the upper surface of each of the channels  12  and  13  in line with their webs. The stiffeners  14  are coped on their lower sides to conform to the upper surfaces of channels  12  and  13 , while the upper corner of the stiffeners at the straight end of the track  11  has a large chamfer. The stiffeners  14  add both strength and rigidity to the track assembly  11 .  
         [0037]     The channels  12  and  13  are spaced apart parallel with their flanges projecting inwardly. Multiple angle crossmembers  16  are placed on top of the upper flanges and welded horizontally and perpendicularly to those upper flanges of the channels  12  and  13  in order to tie the channels together. For example, three crossmembers  16  are used in the track  11  as illustrated in  FIGS. 2 and 3 . One crossmember  16  is positioned adjacent to the start of the arcuate portion of the channels  12  and  13 , another crossmember  16  is adjacent to the righthand end of the straight portion of the track  11 , and a third crossmember  16  is spaced a short distance inwardly away from the second crossmember.  
         [0038]     The vertical flange of each angle crossmember  16  has a central horizontal hole at approximately midheight to accommodate the trolley actuator screw  24 . Additionally, on each side of the central hole at the same height and equispaced from the central hole is located a mounting hole for the attachment of a plain bearing  17 . Plain bearing  17  is typically a rectangular prismatic block with a central horizontal hole for journaling the actuator screw  24 . Whenever the bearing  17  has its central hole aligned with that of a crossmember  16 , the mounting holes match the mounting holes of the angle crossmembers  16 . Bearing retainer screws  18  and bearing retainer nuts  19  are used with the mounting holes of the crossmembers  16  and the bearings  17  to coaxially attach the bearings  17  to the crossmembers  16 .  
         [0039]     The trolley actuator screw  24  is a long right circular cylindrical rod with a male threaded central section, a short reduced diameter first end having a male thread at its distal end, and an elongated reduced diameter shank  26  at the other end. The extreme end of the shank  26  has a flat offset from the cylindrical screw axis so that the actuator screw handwheel  38  can be attached. The diameters of the said first end of the screw  24  and its shank  26  are the same and are a slip fit to the bearings  17 .  
         [0040]     The trolley actuator screw  24  is mounted in the set of bearings  17  so that the first end of the screw  24  is supported in the bearing  17  near the arcuate end of the track  11  land the shank  26  at the opposite end of the screw  24  is supported in the other two bearings  17 . The actuator screw  24  is retained in place by actuator screw retainer nut  25  that is attached to the thread at the first end of the actuator screw  24 .  
         [0041]     A rectangular prismatic driven nut  30  has a central horizontal through hole  31  which is drilled and tapped with a female thread mateable with the male thread of the trolley actuator screw  24 . The driven nut  30  is threadedly engaged with the screw  24  between the first and third bearings  17  of the track  11 . A horizontal drilled and tapped hole with its axis intersecting the axis of threaded hole  31  is located on each of the lateral sides of driven nut  30 . The drilled and tapped lateral holes in driven nut  30  are used to attach the driven nut  30  to the trolley subassembly  39  and to prevent the rotation of driven nut  30 . A conventional handwheel  38  is attached to the actuator screw  24  adjacent the straight end of the track  11  by means of the flat on the shank  26  of the screw.  
         [0042]     The trolley actuator screw  24  is axially fixed with the nut  25 , yet turning the handwheel  38  will rotate the screw  24 . As the handwheel  38  rotates the actuator screw  24 , the nonrotating driven nut  30  is selectably caused to reciprocate along the threaded axis of the screw  24 .  
         [0043]     The trolley subassembly  39 , shown in detail in FIGS.  4  to  6 , consists of a first trolley  40 and a second trolley  60 , which are linked to pivot about a central horizontal axis  70 . The trolley assembly  39  is mounted to reciprocate within track  11  between the inwardly facing flanges of the track. The trolley assembly  39  can be caused to enter the arcuate end of the track  11  and is limited in its travel by a travel stop bar  34 . The travel stop bar  34  is a threaded right circular cylindrical rod which extends from righthand channel  12  across the track  11  to lefthand channel  13 . The travel stop bar  34  is mounted horizontally and extends through coaxial corresponding transverse holes located near the upper arcuate end of channels  12  and  13 . The travel stop bar  34  is retained in position by a travel stop bar nut  35  on each of its external ends.  
         [0044]     The first trolley  40  is configured to support the choke actuator  203  under the track  11 . The second trolley  60  contributes vertical support to the first trolley  40  and, because it is attached to the driven nut  30 , serves to transmit horizontal positioning loads to the first trolley  40 .  
         [0045]     First trolley  40  consists of a backbone plate body  41  with mounted vertical restraint rollers  44  and horizontal restraint rollers  45  to maintain and control the position of the trolley  40  within the guiding track  11 . The first trolley body  41  is a thick horizontal plate having a generally rectangular outline with a reduced width central “waist” and lightening holes. Transverse horizontally drilled and tapped holes are located slightly below midheight near the four corners of the body  41 . Each of these holes serves to mount a horizontal support roller  44  on a shaft provided by a roller mounting screw  46 .  
         [0046]     A rectangular prismatic flat crossbar  42  is transversely mounted underneath body  41  at about midlength of the body. The crossbar  42  is attached to the body  41  by hex screws  47  engaged into drilled and tapped holes in the body. The crossbar  42  mounts a vertical restraint roller  45  on each side of the body  41 . A vertical restraint roller  45  is mounted at each end of the upper side of the crossbar  42  by a vertical roller mounting screw  46  that passes through a drilled and tapped hole in the crossbar  42 .  
         [0047]     Dependent plates  43  are Y-shaped with the arms of the Y up and clearance holes at the upper tips of the Y and a pair of bolt holes at the bottom. The central notch of the Y permits the plates  43  to clear the crossbar  42 . The holes at the upper end of the Y are positioned to be a slip fit to the horizontal roller mounting screws  46  and are positioned thereon. At the left end of the first trolley  40  as shown in the figures, each dependent plate  43  is spaced away from the body  41  by a short right circular cylindrical tubular second cylindrical spacer  49 , which is concentrically mounted on a horizontal roller mounting screw  46 . At the right end, each dependent plate is spaced away from the body  41  by an intertrolley connector link having the same thickness as the cylindrical spacer  49 . Each horizontal roller mounting screw  46  at the right end of the body  41  passes through, from its hex head end, a vertical support roller  44 , a dependent plate  43 , and an intertrolley connector link  62 . The coaxial righthand horizontal roller mounting screws  46  on body  41  provide a horizontal rotational axis for flexing in the vertical plane of the trolley assembly  39 .  
         [0048]     A large crossbar  50 , used to support the choke actuator  203 , is a thick rectangular prismatic plate mounted horizontally at the bottom ends of the Y of the spaced apart parallel dependent plates  43  by mounting screws  52  engaged in the bottom holes of the plates  43  and drilled and tapped horizontal holes in crossbar  50 . Crossbar  50  has on its center vertical transverse plane two symmetrically spaced apart vertical hanger screw holes  51  which correspond to similar drilled and tapped holes in bosses  206  on the upper surface of the choke valve actuator  203 . Hanger screw holes  51  mount downwardly extending actuator hanger screws  94  for attaching to the actuator.  
         [0049]     The second trolley  60  is very similar to first trolley  40  in construction, but with the following differences. The body  61  of second trolley  60  is similar to that of the body  41  except for a short rectangular horizontal prismatic protrusion on its righthand end centerline. The protrusion has opposed horizontal coaxial drilled and tapped holes for mounting a pair of link attachment screws  65 . Additionally, spaced toward the center of body  61  from the lefthand mounting holes for the horizontal axis vertical support rollers  44  and their roller mounting screws  46  is another pair of opposed horizontal coaxial drilled and tapped holes for mounting a pair of link attachment screws  65 .  
         [0050]     The first and second trolleys are linked together with a horizontal intertrolley connection link  62 . The intertrolley connection link  62  is rigidly mounted to the body  61  on each lefthand lateral side by a link attachment screw  65  and a roller mounting screw  46 . The intertrolley connection link  62  is a vertical rectangular flat plate which is horizontally elongated to extend leftward beyond body  61  and has three horizontal through holes. The leftmost through hole is journaled on a righthand horizontal roller mounting screw  46  of trolley  40  and the middle hole is a slip fit onto the lefthand horizontal roller mounting screw  46  of trolley  60 . The righthand hole is a slip fit for a link attachment screw  65  as described above. This arrangement of the horizontal intertrolley connection link  62  permits the first and second trolleys to pivot about horizontal axis  70  that is coaxial with the horizontal axis of the righthand vertical support rollers  44  of trolley  40 . The lefthand vertical support roller screw  46  of second trolley  60  has a second cylindrical spacer  49  located between the roller  44  and link  62 . The righthand vertical support roller screws  46  spaces the roller  44  outwardly from body  61  by a first cylindrical spacer  48  that is similar to the second spacer  49 , but longer.  
         [0051]     A rectangular elongate attachment link  66  having a horizontal through hole at each end is positioned in the vertical plane and lapped onto each side of the rightward protrusion of body  61 , where it is journaled at one end by a screw  65 . The other end of each attachment link  66  is journaled on a second screw  65  that is mounted in one of the horizontal transverse holes in driven nut  30 . This arrangement permits the relative alignment of second trolley  60  to vary with regards to the axis of actuator screw  24  as the track  11  departs from being parallel to screw  24 .  
         [0052]     A support structure, as shown in  FIG. 7 , is provided to rigidly mount the track  11  with its trolley assembly  39  to the choke valve  201 . Symmetrically positioned and transversely mounted by welding to channels  12  and  13  underneath track  11  at their righthand ends are a pair of channel crossmembers  90 . The webs of channels  90  are vertical and parallel and their flanges face inwardly in an opposed fashion. Parallel to and symmetrically spaced apart from the longitudinal centerline of track  11  are elongate rectangular choke mounting bars  91 , which are attached by welding symmetrically to the outer ends of the lower flanges of crossmembers  90 . The distal ends of the bars  91  have vertical holes mounting downwardly extending choke mounting screws  92 . The hole pattern in the bars  91  corresponds to an array of drilled and tapped mounting holes in the upper surface of choke valve  201 .  
         [0053]     An alternative embodiment of the choke manipulator  300  is shown in FIGS.  8  to  12 . the choke manipulator  300  can be both rotated in the horizontal plane and reciprocated toward and away from the choke valve body  201 . Referring to FIGS.  8  to  10 , the basic manipulator assembly  300  is shown in an oblique, side profile, and oblique exploded views. The major components of the manipulator assembly include track  311 , the trolley assembly  340 , and the supporting means for the manipulator  300 , which consists of members rotator base  359  and choke mounted base  363 . The actuator  203  is supported by an actuator hanger  367 , which is dependent from the trolley  340  and is rotatable about a vertical axis.  
         [0054]     The track  311  is composed of horizontal mirror image righthand and lefthand straight channels,  312  and  313  respectively, which have vertical webs. Vertical stiffeners for the track  311  are not shown in this case, but could be included readily in a manner similar to that used with plates  14  on the track  11  of the first manipulator embodiment  10 . The channels  312  and  313  are spaced apart parallel with their flanges projecting inwardly. A generally rectangular transverse plate  315  is coped to fit between the flanges of channels  312  and  313  and welded at the outer end of the track  311  to rigidize the track and provide an end stop.  
         [0055]     Multiple angle crossmembers  16  are placed on top of the upper flanges and welded horizontally and perpendicularly to those upper flanges of the channels  12  and  13  to tie the channels together to form a track. For example as shown in  FIGS. 9 and 10 , two crossmembers  16  are used. One crossmember  16  is placed adjacent the lefthand end of the channels  312  and  313  and another crossmember  16  is placed at the righthand end of the channels.  
         [0056]     The vertical flange of each angle crossmember  16  has a central horizontal hole at approximately midheight to accommodate the actuator screw  324 . Additionally, on each side of the central hole at the same height and equispaced from the central hole is located a mounting hole for the attachment of a plain bearing  17 . Plain bearing  17  is a rectangular prismatic block with a central horizontal hole for journaling the actuator screw  324  and mounting holes matching those of the angle crossmembers  16  when the bearing has its central hole aligned with that of the crossmembers. Bearing retainer screws  18  and bearing retainer nuts  19  are used with the mounting holes of the crossmembers  16  and the bearings  17  to coaxially attach the bearings to the crossmembers.  
         [0057]     Actuator screw  324  is a long right circular cylindrical rod with a male threaded central section, a short reduced diameter first (lefthand) end having a male thread at its distal end, and a short reduced diameter shank  326  at its second end. The extreme end of the shank  326  has a flat offset from the cylindrical screw axis so that shaft coupling  328  can be attached. The diameters of the first end of the screw  324  and the shank  326  are generally about the same and are a slip fit to the bearings  17 . The screw  324  is mounted in the set of bearings  17  so that the first end of the screw is supported in the bearing near the outer end of the track  311 , while the shank  326  of the screw is supported in the other bearing  17 . Actuator screw  324  is retained in place by actuator screw retainer nut  25  being attached to the thread at the first end of the actuator screw  324 .  
         [0058]     A rectangular prismatic driven nut  330  has a central horizontal through hole  331  which is drilled and tapped with a female thread mateable with the male thread of actuator screw  324 . The driven nut  330  is threadedly engaged with the screw  324  between the bearings  17  of the track  311 . Horizontal through holes with their axes parallel to and laterally offset from the axis of threaded hole  331  are located in driven nut  330 . The drilled and tapped holes in driven nut  330  are used to prevent its rotation.  
         [0059]     A conventional handwheel  38  is attached to the worm gear reduction gear box  380  by means of a second coupling  328  so that the axis of the handwheel projects horizontally transverse to the axis of the track  311 . The output shaft of the reduction gearbox  380  projects horizontally parallel to and in the direction of the longitudinal axis of track  311 . Reduction worm gear box  380  is attached to actuator screw  324  adjacent the inner end of the track  311  by means of the coupling  328  on the adjacent second end of the actuator screw.  
         [0060]     Although the nut  25  axially fixes the screw  324 , the screw  324  can be rotated by handwheel  38  acting through gearbox  380  so that nonrotating driven nut  330  can be selectably caused to reciprocate along the axis of the screw. Gearbox  380  is mounted on bracket angle  381 , which is transversely mounted by welding at the extreme righthand end of track  311  by its vertical downwardly projecting flange and with its long flange horizontal and projecting to the right. The horizontal flange of bracket angle  381  is drilled for mounting gearbox  380  by means of multiple screw and nut pairs  382 . The horizontal flange of bracket angle  381  is at approximately the same height as the upper flange of the channels  312  and  313 .  
         [0061]     The trolley subassembly  340 , shown in detail in  FIG. 11 , is very similar to the first trolley  40  of the first embodiment  10  of the present invention and uses most of the same components. The trolley subassembly  340  is mounted to reciprocate within track  311  between the inwardly facing flanges of the track. Trolley  340  is configured to support the actuator  203  of the choke under the track  311 . Trolley  340  consists of a backbone plate body  41  mounting horizontal  45  and vertical  44  restraint rollers to maintain and control the position of trolley  340  within the guiding track  311 . First trolley body  41  is a thick horizontal plate having a generally rectangular outline with a reduced width central “waist” and lightening holes.  
         [0062]     Transverse horizontally drilled and tapped holes are located slightly below midheight near the four comers of the body  41  and each serves to mount a vertical support roller  44  on a shaft provided by a roller mounting screw  46 . A rectangular prismatic flat crossbar  42  is transversely mounted underneath the body  41  at about midlength of the body  41 . Two hex screws  47  engaged into drilled and tapped holes in the body  41  support the crossbar  42 . In a drilled and tapped hole in the crossbar on the upper side of each of the upper outer tips of the crossbar  42 , a vertical roller is mounted on the crossbar  42  by a mounting screw  46  that also supports a coaxial horizontal support roller  45 .  
         [0063]     Dependent plates  43  are Y-shaped with the arms of the Y up and clearance holes at the upper tips of the Y and a pair of bolt holes at the bottom. The central notch of the Y permits the plates  43  to clear the crossbar  42 . The holes at the upper end of the Y are positioned to be a slip fit to the horizontal roller mounting screws  46  and are positioned thereon. At both the left end and right end of trolley  340 , the dependent plate  43  is typically spaced away from the body  41  by a short right circular cylindrical tubular second cylindrical spacer  49 , which is concentrically mounted on a horizontal roller mounting screw  46  as shown in  FIG. 6 .  
         [0064]     The actuator support crossbar  350  is a thick rectangular prismatic plate. The crossbar  350  is mounted horizontally at the bottom ends of the Y of the spaced apart parallel dependent plates  43  by means of mounting screws  52  engaged in the bottom holes of the plates  43  and drilled and tapped horizontal holes in crossbar  350 . Crossbar  350  has on its center a vertical hanger screw hole  351 . The hanger screw hole  351  mounts downwardly extending actuator hanger  367  for attaching to the choke actuator  203 .  
         [0065]     Transverse vertical attachment link  356  is a rectangular plate with a pair of through holes at its lower end symmetrically spaced apart from the plate vertical longitudinal midplane. A clearance through hole for the actuator screw  324  is located near the upper end of plate  356  on the vertical longitudinal midplane. Laterally offset equally to each side of the clearance hole in plate  356  are two through holes that are aligned with the bolt holes in driven nut  330  and with which the driven nut is attached to plate  356  using screw  18  and nut  19 . In addition, the transverse face of the trolley body  41  has two horizontal drilled and tapped holes at midheight of the body plate  41 .and equispaced from the longitudinal centerplane of the body  41 . The spacing of these holes in body  41  is the same as that of the lower holes in plate  356  and link attachment screws  357  are engaged through these holes to attach link plate  356  to the body  41  of trolley  340 .  
         [0066]     Rotator base  359 , shown in  FIG. 12 , is attached to the bottom side of track  311  at its righthand end and serves to provide a rotatable support between the track assembly  311  and the choke valve  201 . As seen in FIGS.  8  to  10 , the rotator base  359  has a rotator upper plate  360 , worm gear  361 , rotator keeper nut  362 , rotator keeper washer  396 , rotator top bearing  397 , and rotator bottom bearing  398 .  
         [0067]     The rotator upper plate  360  is a thick horizontal plate with one circular end and the other end squared. On the centerline of the circular portion of plate  360  and extending downwardly from the lower surface of the plate is worm gear  361 . Worm gear  361  has a large diameter worm gear located on an upper cylindrical portion and a downwardly extending concentric reduced diameter right circular cylindrical lower hub joined to it by a transverse shoulder. The lower end of the hub of worm gear  361  has an upwardly extending drilled and tapped hole on its axis that is engagable by rotator keeper screw  362 .  
         [0068]     The rotator top bearing  397  is a transversely flanged thin walled right circular cylindrical tube having a bore which has a close slip fit to the lower hub of the worm gear  361  and a flange diameter the same as that of the toothed portion of worm gear  361 . The bearing  397  is generally made of a lubricious plastic or a bearing bronze. The rotator bottom bearing  398  has the same outer diameter as the flange of bearing  397  and the same inner diameter as bearing  397 . Rotator bottom bearing  398  is a thin annular ring typically made of the same material as that of the rotator top bearing  397 .  
         [0069]     The thick right circular cylindrical washer  396  has the same outer diameter as lower bearing  398  and a central clearance hole for accommodating rotator keeper screw  362 . Rotator top bearing  397  is mounted on the hub of worm gear  361  with its flange abutting the downward facing shoulder of the gear. The lower bearing  398  is mounted on the upper surface of washer  396  and both are clamped to the lower end of the worm gear  361  by screw  362 . The spacing between the flange of bearing  397  and the upper face of bearing  398  is slightly more than the thickness of the plate  365 .  
         [0070]     The rotator assembly  359  is assembled by the welding of the worm gear  361  to the rotator upper plate  360 . The upper surface of the rotator upper plate  360  is welded to the bottom of the righthand end of the track assembly  311  so that the horizontal track centerline intersects the vertical centerline of the rotator assembly and the track extends in the direction of the squared end of the rotator upper plate  360 .  
         [0071]     The choke mounted base subassembly  363  has a horizontal rectangular upper pivot plate  365 , two transverse riser plates  364 , and two choke mounting bars  366 . This subassembly mounts a handwheel driven worm  383  which is engaged to the worm gear  361  of the rotator base  359 . Thick upper pivot plate  365  has a large circular through hole to journal bearing  397  of the rotator base  359 . The lower side of the flange of bearing  397  and upper side of bearing  398  then can be supported on the upper and lower surfaces of the upper pivot plate  365 , respectively.  
         [0072]     A pattern of small vertical drilled and tapped holes is offset to one side of the pivot plate from the large through hole in the central portion of the plate. This hole pattern is for mounting the pillow blocks  385 . The rectangular transverse riser plates  364  are attached to the lower transverse face of plate  365  by welding. A first riser plate  364  is attached to plate  365  with its outer transverse face flush with the transverse lefthand face of the plate  365 . The second riser plate  364  is positioned parallel to the first symmetrically about the large center through hole, so that it is inward to the left from the righthand transverse edge of plate  365 .  
         [0073]     The choke mounting bars  366  are rectangular cross-section bars with symmetrically placed vertical through holes at their ends for accommodating choke attachment screws  392 . The choke mounting bars  366  are welded horizontally transverse to and below the riser plates  364  at the outer ends of the riser plates  364 . When assembled, the hole pattern in the choke mounting bars  366  corresponds to an identical pattern of drilled and tapped holes on the upper side of the body of choke valve  201  so that screws  392  can be used to attach the choke mounted base  363  to the choke.  
         [0074]     A helically toothed worm  383  is concentrically mounted on an elongate cylindrical worm shaft  384  and supported by two bearing pillow blocks  385 . One pillow block is positioned adjacent a first end of the shaft  384 , while the other pillow block is set back from the second end of the shaft. The second end of the shaft  384  has a flat provided whereby another handwheel  38  can be mounted at the second end for selectably driving the shaft. The height of the pillow blocks  385  is such that, when the pillow blocks  385  are mounted onto the upper surface of plate  365  by screws  386 , the worm  383  is properly positioned vertically with respect to worm gear  361  of the rotator base  359 . The transverse positioning relative to the centerline of worm gear  361  of the mounting holes for the pillow blocks  385  on plate  365  is such that the worm  383  and the worm gear  361  are suitably meshed. The worm shaft  384  extends laterally sufficiently beyond the side of choke mounted base  363  that its handwheel  38  is freely accessible and the rotator base  359  is able to rotate through a large arc.  
         [0075]     The actuator hanger  367  has a stepped vertical shaft with a large transverse flange  370  at its lower end. The upper end of hanger  367  has a male thread, below which is a concentric cylindrical shank. A transverse flange joins the lower end of the round cylindrical shank to the relatively larger diameter main round cylindrical body of the actuator hanger  367 . Two diametrically opposite vertical holes are drilled in the flange  370  at the lower end of hanger  367  so that screws  94  can be used to engage the threaded holes in the bosses  206  of the choke actuator  203 . Hanger washer  368  is a round disk washer with a central hole to accommodate the threaded section and the shank of hanger  367 . The outer diameter of the washer  368  is generally the same as the diameter of the main cylindrical body of hanger  367 .  
         [0076]     Two thin flat annular bearing washers  369  are generally fabricated from a lubricious plastic or bearing bronze. The outer diameter of the bearings  369  correspond to both the outer diameter of hanger washer  368  and of the main round cylindrical body of the actuator hanger  367 . The threaded portion and shank of actuator hanger  367  are assembled into the hanger screw hole  351  of the trolley  340  with a bearing  369  on each side of the actuator support crossbar  350  and the lower bearing abutting the transverse shoulder of the hanger, washer  368  on top of the upper bearing  369 , and hanger nut  371  and hanger jam nut  372  engaged with the thread of hanger  367  to retain the bearings  369  and washer  368  in place. The nuts  371  and  372  are not made up so tightly that the hanger  367  cannot be readily rotated.  
         [0000]     Operation of the Invention  
         [0077]     The arrangements shown in the drawings of this document can be varied somewhat from what is shown herein without departing from the spirit of the present invention. Likewise, the operational sequence can be varied somewhat from what is described herein without departing from the spirit of the invention.  
         [0078]     The operation of the first embodiment  10  of the present invention is as follows. The manipulator  10  is mounted to drilled and tapped holes in the upper surface of the choke valve  201  by means of screws  92  engaged through the vertical holes in the ends of the choke mounting bars  91 . The track  11  is then positioned so that it extends outwardly on the actuator  203  side of the choke  201  and is aligned with the axis of the choke. The arrangement of the trolley assembly  39  is such that the lower surface of its actuator support crossbar  50  is coplanar with the top surfaces of the bosses  206  of the choke actuator  203 .  
         [0079]     The handwheel  38  is rotated, thereby causing driven nut  30  and trolley assembly  39  to move along track  11  until the holes  51  in the actuator support crossbar  50  are aligned with the corresponding holes in the bosses  206  of the choke actuator  203 . Screws  94  are then engaged with the choke actuator by means of the holes in the bosses  206  so that the trolley assembly  39 , the track  11 , the track support members  90  and  91 , and the rigidly mounted choke  201  are supporting the choke actuator  203 . At this point, the attachment nut  204 , which connects the choke actuator  203  and the internal valve components of the choke valve  201  to the choke valve body at its lefthand neck, is disconnected.  
         [0080]     The handwheel  38  is then rotated so that the trolley assembly  39  and its attached actuator  203  and the internals of the choke valve  201  are withdrawn axially from choke body cavity. If it is desired to service these withdrawn components horizontally, then the trolley  39  is not moved onto the arcuate portion of the track  11 . However, if it is desired to rotate the actuator  203  so that components do not readily drop out of the actuator housing during service, the trolley can be shifted sufficiently so that the first trolley  40  moves well up into the arcuate portion of the track, thereby tilting the lefthand, cover end of the actuator upwardly. The trolley assembly  39  is prevented from excessive outward travel by travel stop bar  34 . The reassembly of the choke system uses a reverse procedure to the disassembly described above.  
         [0081]     The operation of the second embodiment  300  of the present invention is as follows. The manipulator  300  is mounted to drilled and tapped holes in the upper surface of the choke valve  201  by means of screws  392  engaged through the vertical holes in the ends of the choke mounting bars  366 . The track  311  is then positioned so that it extends outwardly on the actuator  203  side of the choke  201  and aligned with the axis of the choke. The arrangement of the trolley assembly  340  is such that the lower surface of its actuator support crossbar  350  is coplanar with the top surfaces of the bosses  206  of the choke actuator  203 .  
         [0082]     The first handwheel  38  is rotated causing driven nut  330  and trolley assembly  40  to be driven through gearbox  380  and the actuator screw  324  and to move along track  311  until the holes in the flange  370  of the actuator hanger  367  are aligned with the corresponding holes in the bosses  206  of the choke actuator  203 . Screws  94  are then engaged with the actuator  203  by means of the holes in the bosses  206  so that the trolley assembly  340 , the track  311 , the rotator base  359 , the choke mounted base  363 , and the rigidly mounted choke  201  are supporting the actuator  203 . At this point, the attachment nut  204 , which connects the actuator  203  and the internal valve components of the choke valve  201  to the choke valve body at its lefthand neck, is disconnected.  
         [0083]     The first handwheel  38  is then again rotated so that the trolley assembly  340  and its attached actuator  203  and the internals of the choke valve  201  are withdrawn axially from choke body cavity. If it is desired to rotate the choke actuator  203  in the horizontal plane so that components are more readily accessible, the actuator hanger  367  can be directly rotated.  
         [0084]     Alternatively, the second handwheel  38  can actuate the worm  383  to drive worm gear  361  and rotate rotator base  359  and its attached track  311 . Both rotational methods can be used together to achieve a desired alignment. Choke reassembly uses a reverse procedure of the disassembly described above.  
         [0085]     Advantages of the Invention  
         [0086]     The first embodiment  10  of the present invention permits servicing of the choke valve  201  and the choke actuator  203  at the height of the choke valve axis, which is normally an easier working position than at ground level. Additionally, it is very advantageous to be able to tilt the actuator upwardly so that its internal components are not so easily dropped during servicing.  
         [0087]     The second embodiment  300  of the present invention permits the actuator  203  and the internals of the choke valve  201  to be swiveled in the horizontal plane so that they can be placed in a more conveniently accessible position. This is an important advantage when the choke is located in the middle of a complex flow manifold where conventional access would be problematic.  
         [0088]     A common advantage to both embodiments  10  and  300  of the present invention is the reduced susceptibility to stick-slip movement of the trolley supporting the actuator  203  and the choke valve  201  components. This improvement is due to the screw drive and the gear drive arrangements for the manipulators, since these operational means are much smoother, stiffer, and more forceful than manually urging the suspended choke system components to new positions.  
         [0089]     A further important advantage is that the mechanical advantage of the screw and/or gear drives of the present manipulators permits controlled movement of the suspended components of the choke even when the movements are not in a very level position. A common advantage for both types of manipulator is that is markedly eases the assembly and disassembly and servicing of the typically heavy components of the choke valve, leading to reduced strain and injury in service personnel and to reduced choke valve system component damage due to dropped or impacted components.  
         [0090]     These and other advantages will be obvious to those skilled in the art. Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.