Device for positioning and stabbing casing from a remote selectively variable location

• US 4,921,386 A
• Filed: 06/06/1988
• Issued: 05/01/1990
• Est. Priority Date: 06/06/1988
• Status: Expired due to Term

• Current Assignee: Frank's Casing Crew & Rental Tools Incorporated (Frank's International N.V.)
• Original Assignee: Charlena Harrel, John Harrel
• Inventors: McArthur, James R.
• Primary Examiner(s): Werner, Frank E.
• Application Number:
  US07/203,252
• Time in Patent Office: 694 Days
• Field of Search: 414/732, 414/744.8, 414/738, 414/739, 414/735, 414/729, 414/22.68, 414/22.71, 414/753, 414/751, 414/745.1, 414/730, 414/22.63, 414/22.61, 414/22.58 , 414/22.51, 414/745.2, 175/52, 175/85, 901/39, 294/902, 294/88
• US Class Current: 414/22.51
• CPC Class Codes: E21B 19/14 Racks, ramps, troughs or bins, for holding the lengths of rod singly or connected; Handling between storage place and borehole E21B19/20, E21B19/22 take precedence
• CPC Class Codes: E21B 19/16 Connecting or disconnecting pipe couplings or joints E21B19/20 takes precedence

Abstract

A casing stabbing apparatus which includes a derrick bracket subassembly for attachment to a derrick, and a boom having an end pivotally connected to the bracket assembly for pivotation about a vertical axis and about a horizontal axis. A pair of arcuate casing gripping jaws is pivotally connected to the second end of the boom. A piston and cylinder assembly extends between the jaws to selectively converge and diverge the jaws. A second piston and cylinder assembly extends between the bracket assembly and the boom to elevate the boom by pivotation about a horizontal pivotal axis. A third piston and cylinder assembly extends between the bracket assembly and the boom to swing the boom laterally in pivotation about a vertical axis. A remote automatic control subassembly enables the casing stabbing operation to be carried out from a remote location by the use of a hand held wand.

Claims

1. A casing stabbing apparatus which comprises:

a derrick bracket subassembly adapted for attachment to a structural member of a well derrick;

a boom and jaw subassembly detachably connected to said derrick bracket subassembly and including;

an elongated, hollow, extensible boom having one end pivotally connected to said derrick bracket subassembly for pivotation about a vertical axis and about a horizontal axis;

a pair of arcuate casing engaging jaws pivotally mounted on the end of said boom opposite its end connected to said derrick bracket subassembly;

means for selectively pivoting said boom about said horizontal axis to raise and lower the end of said boom carrying said jaws;

means for selectively extending and retracting the boom, said means for selectively extending and retracting the boom comprising;

a boom extending piston and cylinder subassembly located in the boom and including;

a piston rod portion connected to one end portion of said boom; and

a cylinder having an end pivotally connected to said derrick bracket subassembly for pivotation about common horizontal and vertical axes with said boom;

a yawing piston and cylinder subassembly extending at an acute angle to the longitudinal axis of the boom and connected to a medial portion of the boom for pivoting the boom about an axis which is substantially vertical at a time when said boom extends substantially horizontally;

radially adjustable roller means carried on said arcuate jaws for selectively adjusting the diametric dimension defined inside said jaws to thereby facilitate stabbing casing sections of varying diametric sizes; and

a piston and cylinder subassembly connected between said jaws for pivoting said jaws in a converging or a diverging movement;

a limit switch subassembly positioned below said boom to be contacted during the downward pivotation of the boom to lower the end of said boom carrying said jaws, and at a time when said boom extends substantially horizontally;

deactivating means connected to said limit switch subassembly and to said means for pivoting the boom to raise and lower the boom for deactivating said pivoting means for raising and lowering the boom in response to a signal from said limit switch subassembly;

a remote control assembly detachably mounted on said boom housing subassembly, said remote control assembly including a plurality of electrically controlled hydraulic valves for selectively supplying hydraulic power fluid to said piston and cylinder subassemblies;

a portable hand control device remote from said hydraulic valves of the remote control assembly and having a plurality of hand maniputable electrical switches thereon;

a control cable connected between the portable hand control device and the remote control assembly for transmitting control signals from the portable hand control device to the remote control assembly;

a power cable connected to the remote control assembly for supplying electrical power thereto;

a hydraulic power fluid supply conduit connected to said remote control assembly for supplying hydraulic power fluid to said electrically controlled hydraulic valves; and

a hydraulic power fluid return conduit connected to said remote control assembly for receiving hydraulic power fluid discharged from said piston and cylinder subassemblies via said electrically controlled hydraulic valves.

2. A casing stabbing apparatus comprising:

an elongated, extensible boom;

a pair of arcuate jaws pivotally connected to one end of the boom and pivotally convergent with respect to each other for engaging a casing section, each of said jaws having a concave inner side;

a plurality of spaced roller elements mounted in each of said jaws on the concave inner side thereof, and each adjustable radially inwardly and outwardly on the respective jaws;

means for elevating the end of the boom carrying said jaws without elevating the opposite end of said boom;

means for laterally displacing the end of the boom carrying said jaws;

a boom housing subassembly pivotally receiving the end of said boom opposite its end to which said jaws are connected, and supporting said laterally displacing means;

trunnion means detachably and pivotally connected to, and supporting, said boom housing subassembly, said trunnion means comprising;

a base plate;

a trunnion pedestal extending upwardly from the base plate;

a horizontally extending lower trunnion plate secured to the top of the trunnion pedestal;

a horizontally extending upper trunnion plate rotatably secured to the upper side of said lower trunnion plate; and

means for selectively fixing said upper trunnion plate to said lower trunnion plate;

support plate means secured to the upper side of said horizontally extending upper trunnion plate for movement therewith, and including two horizontally spaced pairs of spaced clevis plates; and

means detachably connecting said boom housing subassembly to said support plate means for pivotation of the boom housing subassembly about a horizontal axis of pivotation, said means detachably connecting said boom housing subassembly to said support plate means comprising;

a facing plate;

an upper, horizontally extending plate joined edge-to-edge to said facing plate and extending normal thereto; and

a pair of horizontally spaced journal and clevis plates secured to said upper, horizontally extending plate, and each pivotally connected to one of the pairs of said clevis plates included in said support plate means, and each further including a portion pivotally journaled to said boom housing subassembly.

3. A casing stabbing apparatus as defined in claim 2 wherein said boom housing subassembly comprises:

a pair of spaced end plates;

journal shafts projecting horizontally from said end plates and through said last-mentioned portion of said journal and clevis plates to pivotally support said boom housing subassembly on said means detachably connecting said boom housing subassembly to said support plate means; and

a pair of spaced housing plates secured to said end plates and forming therewith a right parallelepiped open at one side and receiving through said open side said pivotally received end of said boom.

4. A casing stabbing apparatus as defined in claim 2 and further characterized as including a derrick bracket subassembly bolted to said trunnion means and adapted for attachment to a drilling derrick.

5. A casing stabbing apparatus as defined in claim 2 wherein each of said roller elements comprises:

a bar slidably mounted in one of said jaws for movement radially inwardly and radially outwardly in the respective jaw in which it is mounted;

a roller rotatably mounted in the radially inner side of said bar for undergoing rotation when said roller is in contact with a tubular member passed through, and engaged by, said jaws; and

means for adjustably fixing the bar at a selected radial position in the respective bar in which it is mounted.

6. A system for making up a vertically extending string of threadedly interconnected tubulars, including large diameter casing, by serially threaded interconnection of sections of tubulars in end-to-end vertically extending relation to each other comprising:

means for supporting a first section of tubular in a vertical orientation with the upper end stationary and the lower portion in a well bore;

a derrick erected above said supporting means and having sides, an upper end and a rig floor at which said tubular supporting means is located;

a travelling crown block supported in the upper end of the derrick and lowerable toward said tubular supporting means and said rig floor for suspending a second section of tubular above the rig floor; and

a tubular stabbing and positioning means demountably connected to a side of the derrick at a location which facilitates engaging a medial portion of said second section of tubular, said tubular stabbing and positioning means including;

a derrick bracket subassembly detachably secured to a side of said derrick; and

a boom and jaw subassembly pivotally connected to said detachably secured derrick bracket subassembly, said boom and jaw subassembly further including;

an elongated, extensible boom having a first end and having a second end pivotally connected to said detachably secured derrick bracket subassembly for pivotation about a vertical axis as said boom is yawed from side-to-side at a time when said boom extends substantially horizontally;

a yawing piston and cylinder subassembly connected to said boom and extending at an acute angle to the longitudinal axis of the boom for swinging said boom from side-to-side in pivotation about a pivotal axis which is substantially vertical at a time when said boom is substantially horizontal;

a boom extension piston and cylinder subassembly for selectively extending and retracting the boom to lengthen and shorten the boom;

two spaced arcuate jaws pivotally mounted on said first end of said boom for pivotation about parallel axes as said jaws are swung in a converging movement or in a diverging movement, each of said jaws having a concave inner side;

roller mounted on the concave inner sides of each of said arcuate jaws and facing each other across the space separating said jaws;

means for selectively varying the distance separating the rollers mounted on one jaw from the rollers mounted on the other jaw; and

plate means extending beneath said boom and said yawing piston and cylinder subassembly;

a boom raising piston and cylinder subassembly connected to said plate means at a location between the ends of the boom for raising and lowering the first end of said boom by pivotation of said boom about a horizontal axis when said plate means is moved upwardly by said boom raising piston and cylinder subassembly; and

hydraulic control means detachably mounted on said boom and jaw subassembly.

7. A casing stabbing apparatus as defined in claim 6 wherein said means for selectively varying the distance separating the rollers mounted on one jaw from the rollers mounted on the other jaw comprises:

a plurality of bars each slidably mounted in one of said jaws for movement radially inwardly and radially outwardly in the respective jaw in which it is mounted;

a roller rotatably mounted in the radially inner side of each of said bars for undergoing rotation when said roller is in contact with a tubular member passed through, and engaged by, said jaws; and

means for adjustably fixing each roller-carrying bar at a selected radial position in the respective jaw in which it is mounted, so that, by adjustable fixation, the roller rotatably mounted in the radially inner side of said jaw in which it is mounted can be adjustably set closer to, or farther from, the rollers carried on the other of said jaws.

8. A casing stabbing apparatus as defined in claim 6 wherein said means for selectively varying the space separating the rollers mounted on one jaw from the rollers mounted on the other jaw comprises a jaw converging piston and cylinder subassembly for pivoting said arcuate jaws about said parallel axes to selectively converge and open said jaws.

9. A casing stabbing apparatus as defined in claim 8 wherein said means for selectively varying the space separating the rollers mounted on one jaw from the rollers mounted on the other jaw further comprises:

a plurality of bars each slidably mounted in one of said jaws for movement radially inwardly and radially outwardly in the respective jaw in which it is mounted;

a roller rotatably mounted in the radially inner side of each of said bars for undergoing rotation when said roller is in contact with a tubular member passed through, and engaged by, said jaws; and

means for adjustably fixing each roller-carrying bar at a selected radial position in the respective jaw in which it is mounted, so that, by adjustable fixation, the roller rotatably mounted in the radially inner side of said jaw in which it is mounted can be adjustably set closer to, or farther from, the rollers carried on the other of said jaws from the respective jaw in which said adjustable affixed bars are mounted.

10. A system for making up a vertically extending string of threadedly interconnected large diameter casing sections by serially threaded interconnection of casing sections in end-to-end vertically extending relation comprising:

a rig floor including means for suspending a first section of casing in a vertical orientation below the rig floor with the upper end stationary;

a derrick erected above said supporting means and having sides and an upper end spaced vertically above the rig floor at which said supporting means is located;

a travelling crown block supported in the upper end of the derrick and lowerable toward said supporting means and said rig floor for suspending a second section of casing above the rig floor and above said first section of casing;

a casing stabbing and positioning means demountably connected to a side of the derrick at a location facilitating engagement by said stabbing and positioning means of a medial portion of said second section of casing, said casing stabbing and positioning means including;

a derrick bracket subassembly detachably bolted to a side of said derrick; and

a boom and jaw subassembly pivotally connected to said detachably bolted subassembly, said boom and jaw subassembly further including;

a boom housing subassembly;

an elongated, extensible boom having a first end and having a second end pivotally connected to said boom housing subassembly for pivotation about a vertical axis as said boom is yawed from side-to-side and at a time when said boom extends substantially horizontally;

a yawing piston and cylinder subassembly connected to said boom for swinging said boom from side-to-side in pivotation about a pivotal axis which is vertical at a time when said boom extends substantially horizontally;

a boom extension piston and cylinder subassembly for selectively extending and retracting the boom;

two spaced arcuate jaws pivotally mounted on said first end of said boom for pivotation about parallel axes as said jaws are swung in a converging movement or in a diverging movement, each of said arcuate jaws having a concave inner side;

rollers mounted on the concave inner side of each of said jaws and facing each other across the space separating said jaws;

means for selectively varying the space separating the rollers mounted on one jaw from the rollers mounted on the other jaw; and

a boom elevating piston and cylinder subassembly connected to said boom between the ends thereof for elevating and lowering the first end of said boom by pivotation of said boom about a substantially horizontal axis;

a limit switch subassembly positioned below said boom to be contacted during the downward pivotation of the boom to lower the end of said boom carrying said jaws, and at a time when said boom extends substantially horizontally; and

means connected to said limit switch subassembly and to said means for pivoting the boom to elevate and lower the boom for deactivating said pivoting means in response to a signal from said limit switch subassembly;

a remote control assembly detachably mounted on said boom and jaw subassembly, said remote control assembly including a plurality of electrically controlled hydraulic valves for selectively supplying hydraulic power fluid to said piston and cylinder subassemblies;

a portable hand control device having a plurality of hand maniputable electrical switches thereon;

a control cable connected between the portable hand control device and the remote control assembly for transmitting the control signals from the portable hand control device to the remote control assembly;

a power cable connected to the remote control assembly for supplying power thereto;

a hydraulic power fluid supply circuit connected to said remote control assembly for receiving hydraulic power fluid to said electrically controlled hydraulic valves; and

a hydraulic power fluid return conduit connected to said remote control assembly for receiving hydraulic power fluid discharged from said piston and cylinder subassemblies via said electrically controlled hydraulic valves.

11. A casing stabbing apparatus as defined in claim 10 wherein said limit switch subassembly comprises:

an adjusting screw adjustable in a vertical direction; and

a switch connected to said adjusting screw for actuation when a downwardly acting force is applied to said adjusting screw at the end of the downward pivoting movement of said boom.

12. A casing stabbing apparatus as defined in claim 10 wherein said means for selectively varying the space separating the rollers comprises:

a plurality of bars each slidably mounted in one of said jaws for movement radially inwardly and radially outwardly in the respective jaw in which it is mounted;

a roller rotatably mounted in the radially inner side of each of said bars for undergoing rotation when said roller is in contact with a tubular member passed through, and engaged by, said jaw; and

means for adjustably fixing each roller-carrying bar at a selected radial position in the respective bar in which it is mounted, so that by adjustable fixation, the roller rotatably mounted in the radially inner side of the respective jaw can be adjustably set closer to, or farther from, the rollers carried on the other of said jaws from the respective jaw in which said adjustably affixed bars are mounted.

13. A casing stabbing apparatus as defined in claim 12 wherein said means for selectively varying the space separating the rollers mounted on one jaw from the rollers mounted on the other jaw comprises a jaw converging piston and cylinder subassembly for pivoting said arcuate jaws about said parallel axes to selectively converge and open said jaws.

14. A system for making up a vertically extending string of threadedly interconnected elongated tubulars, including large diameter casing, by threadedly serial interconnection of sections of tubulars in end-to-end, vertically extending relation comprising:

means for supporting a first section of an elongated tubular in a vertical orientation with the upper end stationary;

a derrick erected above said supporting means and having sides, an upper end and a rig floor at which said supporting means is located;

a travelling crown block supported in the upper end of the derrick and selectively lowerable toward said supporting means and said rig floor for suspending a second section of an elongated tubular above the rig floor;

a second section of a tubular having its upper end connected to, and suspended from, said travelling crown block;

a tubular stabbing and positioning means demountably connected to a side of the derrick at a location between said first tubular section supporting means a rig floor therebelow and said travelling crown block thereabove, said stabbing and positioning means engageable with a medial portion of said second elongated tubular section, said tubing stabbing and positioning means including;

a derrick bracket subassembly detachably connected to a side of said derrick, said derrick bracket subassembly including;

a derrick bracket subassembly detachably connected to a side of said derrick, said derrick bracket subassembly including;

an elongated, vertically extending support plate having an upper edge; and

a horizontally extending lower support plate having a horizontal side edge secured to said upper edge of said vertically extending support plate and projecting normal to said vertically extending support plate;

a boom and jaw subassembly detachably connected to said detachably connected derrick bracket subassembly, said boom and said jaw subassembly further including;

an elongated, vertically extending face plate having an upper edge and bearing flatly against the upper surface of said horizontally extending lower support plate;

a vertically extending, clevis plate secured to, and projecting upwardly from, said upper, horizontally extending plate;

means detachably interconnecting said horizontally extending upper plate of said boom and jaw subassembly to said horizontally extending lower support plate of said derrick bracket subassembly whereby said boom and jaw subassembly can be detached from said derrick bracket subassembly without detaching said derrick bracket subassembly from said derrick;

a vertically extending, adjustable leveling screw movably mounted on said vertically extending face plate below said upper edge thereof and selectively adjustable in a vertical direction relative to said vertically extending face plate, and to said upper horizontally extending plate;

a boom housing subassembly including an open sided box;

a pair of horizontally spaced clevis plates secured to said horizontally extending upper plate and projecting upwardly therefrom adjacent opposite ends of said boom housing subassembly;

means pivotally supporting the open sided box of said boom housing subassembly between said horizontally spaced clevis plates for pivotation about a horizontal axis;

an elongated, extensible, selectively variable length boom having a first end and having a second end pivotally connected to the inside of said open sided box for yawing side-to-side pivotation about a vertical axis;

plate means secured to said open sided box and projecting outwardly therefrom beneath said elongated boom in a plane extending substantially parallel to the axis of said boom, said plate means extending over said vertically extending adjustable leveling screw, and contacting said leveling screw at its upper end when said boom housing subassembly is pivoted in said clevis plates to a position in which said extensible boom extends substantially horizontally;

a yawing piston and cylinder subassembly connected to said open sided box and a point on said boom intermediate the ends of said boom for swinging said boom from side-to-side in a yawing movement about said vertical axis inside said open sided box and from side-to-side across the upper side of said plate means;

a boom extension piston and cylinder subassembly connected to said boom for selectively extending and retracting the boom to lengthen and shorten the boom;

two spaced arcuate jaws pivotally mounted on said first end of said boom for pivotation about horizontally spaced, parallel axes as said jaws are swung in a converging movement, or in a diverging movement, each of said jaws having a concave inner side;

rollers mounted on the concave inner sides of each of said arcuate jaws and facing each other across the space separating said jaws;

means for selectively varying the distance separating the rollers mounted on one jaw from the rollers mounted on the other jaw; and

an elongated boom raising piston and cylinder subassembly connected at one point to said plate means extending outwardly from said open sided box at a location on said plate means spaced laterally from said boom, and said boom raising piston and cylinder being connected at a second point of connection to said clevis plate extending outwardly from said upper, horizontally extending plate whereby said boom can be raised and lowered without any interference by said yawing piston and cylinder subassembly, and said yawing piston and cylinder subassembly can move said boom from side-to-side freely and without interference, by said boom raising piston and cylinder subassembly;

a remote control assembly detachably mounted on said boom housing subassembly, said remote control assembly including a plurality of electrically controlled hydraulic valves for selectively supplying hydraulic power fluid to the several piston and cylinder subassemblies;

a portable hand control device remote from said hydraulic valves and having a plurality of hand maniputable electrical switches thereon;

a control cable connected between the portable hand control device and the remote control assembly for transmitting the control signals from the portable hand control device to the remote control assembly;

a power cable connected to the remote control assembly for supplying power thereto;

a hydraulic power fluid supply circuit connected to said remote control assembly for supplying hydraulic power fluid to said electrically controlled hydraulic valves; and

a hydraulic power fluid return conduit connected to said remote control assembly for receiving hydraulic power fluid discharged from said piston and cylinder subassemblies via said electrically controlled hydraulic valves.

15. A system as defined in claim 14 and further characterized as including means at opposite ends of said elongated vertically extending support plate for elevating and lowering said derrick bracket subassembly into and down from said derrick.

16. A system for making up a vertically extending string of threadedly interconnected large diameter elongated casing sections by threaded serial interconnection of the elongated sections of casing in end-to-end, vertically extending relation to each other comprising:

means for supporting a first elongated section of casing in a vertical orientation with the threaded upper end thereof stationary and the lower end portion in a well bore;

a derrick erected above said supporting means and having sides, an upper end and a rig floor at which said casing supporting means is located;

a travelling crown block supported in the upper end of the derrick for suspending a second elongated section of casing above the ring floor and selectively lowerable toward said supporting means and said rig floor;

a second elongated section of casing having its upper end connected to, and suspended from, said travelling crown block;

a casing stabbing and positioning means demountably connected to a side of the derrick at a location between said first casing section supporting means at said rig floor and said travelling crown block, said casing stabbing and positioning apparatus engageable with a medial portion of said second casing section, said casing stabbing and positioning means including;

a bracket subassembly detachably connected to the side of said derrick at a location opposite the medial portion of said second casing section, said derrick bracket subassembly including;

an elongated, vertically extending support plate having a substantially horizontally extending upper edge and having a first apertured lifting area at one end thereof, and a second apertured lifting area at the opposite end thereof; and

a horizontally extending lower support plate having a horizontal side edge secured to said upper edge of said vertically extending support plate and projecting normal to said vertically extending support plate;

a boom and jaw subassembly detachably and movably connected to said detachably connected derrick bracket subassembly, said boom and jaw subassembly including;

an elongated, vertically extending face plate having a horizontally extending upper edge and having an exposed forward side face and bearing flatly against said vertically extending support plate;

a horizontally extending upper plate having a horizontal side edge secured to said upper edge of said vertically extending face plate, and lying flatly against the upper surface of said horizontally extending lower support plate;

a vertically extending boom lift clevis plate secured to, and projecting upwardly from, said horizontally extending upper plate;

means detachably interconnecting said horizontally extending upper plate of said boom and jaw subassembly to said horizontally extending lower support plate whereby said boom and jaw subassembly can be detached from said derrick bracket subassembly without detaching said derrick bracket subassembly from said derrick, and the boom and jaw subassembly and the derrick bracket subassembly can be raised and lowered independently of each other within the derrick to and from the rig floor;

a vertically extending, selectively adjustable leveling and stop screw movably mounted on the exposed forward side surface of said vertically extending face plate below said upper edge thereof, and selectively adjustable in a vertical direction relative to said vertically extending face plate, and said horizontally extending upper plate;

a boom housing subassembly including an open sided box;

a pair of horizontally spaced clevis plates secured to said upper, horizontally extending plate and projecting upwardly therefrom adjacent opposite ends of said boom housing subassembly;

means pivotally supporting said open sided box of said boom housing subassembly between said horizontally spaced clevis plates for pivotation of the box and boom housing subassembly about a horizontal axis;

an elongated, extensible, selectively variable length boom having a first end and having a second end pivotally connected to the inside of said open sided box for yawing side-to-side pivotation about a vertical axis and for pivotation with said boom housing about said horizontal axis;

plate means secured to said open sided box and projecting outwardly therefrom beneath said boom in a plane extending substantially parallel to the longitudinal axis of said elongated boom, said to said horizontal pivotal axis, said plate means extending over said vertically extending adjustable leveling screw, and contacting said leveling screw at its upper end when said boom housing subassembly is pivoted in said clevis plates to a position in which said extensible boom extends substantially horizontally;

a yawing piston and cylinder subassembly connected between said open sided box and a point on said boom intermediate the ends of said elongated boom for and extending at an acute angle to said boom for swinging said boom from side-to-side in a yawing movement about said pivotal axis inside said open sided box, and from side-to-side across the upper side of said plate means;

a boom extension piston and cylinder subassembly connected to said boom for selectively extending and retracting the boom to lengthen and shorten the boom without interference with said yawing piston and cylinder subassembly, or the operation thereof;

two spaced arcuate jaws pivotally mounted on said first end of said boom for pivotation about horizontally spaced, parallel axes as said jaws are swung in a converging movement, or in a diverging movement, each of said jaws having a concave inner side;

rollers mounted on the concave inner sides of each of said arcuate jaws and facing each other across the space separating said jaws;

a jaw opening and closing piston and cylinder subassembly for opening and closing the jaws by pivotation of said jaws about said horizontally spaced, parallel axes; and

an elongated boom raising piston and cylinder subassembly connected at one point to said plate means extending outwardly from said open sided box at a location on said plate means spaced laterally from said boom, and said boom raising piston and cylinder subassembly being connected at a second point of connection to said boom lifting clevis plate which extends upwardly from said horizontally extending upper plate whereby said boom can be raised and lowered without any interference by said yawing piston and cylinder subassembly and said yawing piston and cylinder subassembly can move said boom from side-to-side freely and without interference by said boom raising and lowering piston and cylinder subassembly;

a remote control assembly detachably mounted on said boom housing subassembly, said remote control assembly including a plurality of electrically controlled hydraulic valves for selectively supplying hydraulic power fluid to the several piston and cylinder subassemblies;

a portable hand control device remote from said hydraulic valves and having a plurality of hand maniputable electrical switches thereon;

a control cable connected between the portable hand control device and the remote control assembly for transmitting the control signals from the portable hand control device to the remote control assembly;

a power cable connected to the remote control assembly for supplying power thereto;

a hydraulic power fluid supply circuit connected to said remote control assembly for supplying hydraulic power fluid to said electrically controlled hydraulic valves; and

a hydraulic power fluid return conduit connected to said remote control assembly for receiving hydraulic power fluid discharged from said piston and cylinder subassemblies via said electrically controlled hydraulic valves.