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Publication numberUS3917230 A
Publication typeGrant
Publication dateNov 4, 1975
Filing dateJan 24, 1972
Priority dateJan 24, 1972
Also published asCA979882A, CA979882A1
Publication numberUS 3917230 A, US 3917230A, US-A-3917230, US3917230 A, US3917230A
InventorsCharles D Barron
Original AssigneeByron Jackson Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Well drilling control system
US 3917230 A
Abstract
A well drilling control system in which the hoist mechanism which supports the drill string and which is also employed to move well bore and well head equipment between a floating barge and the well bore and bottom of the sea, is controlled by load sensing and movement sensing signalling transmitters to maintain a predetermined weight on the drill bit during drilling operations and to facilitate properly positioning, raising and lowering of well bore and well head equipment, notwithstanding movement of the floating barge vertically by wave action. A reverse drive mechanism drives the hoist mechanism in a direction to allow downward movement of the drill string, well bore or well head equipment when the acceleration of the barge is so rapid that the supported weight does not overcome the inertia of the drawworks.
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Description  (OCR text may contain errors)

United States Patent 1191 Barron Nov. 4, 1975 [54] WELL DRILLING CONTROL SYSTEM 3,675,900 7/1972 Barren et a1. 254/172 3,698,690 10/1972 Beaver [75] Inventorchifrles Barron Fountam Valley 3,738,614 6/1973 P61613611 254/187 Calif.

[73] Assignee: Byron Jackson Inc., Long Beach, Primary Examiner-Robert Spar Calif. I Assistant ExaminerKenneth Noland [22] Filed: Jan. 1972 Attorney, Agent, or FzrmJohn 0. Evans, Jr.

[21] Appl. No.: 220,284 [57] ABSTRACT A well drilling control system in which the hoist mech- [52] US. Cl 254/173 R; 175/27; 192/51 anism which supports the drill string and which is also [51] Int. C1. B66D 1/48 employed to move well bore and well head equipment [58] Field of Search 254/172, 187, 186, 173; between a floating barge and the well bore and bottom 175/27, 5; 192/51, 87.13, 87.16, 43, 3.27, of the sea, is controlled by load sensing and movement 3.22; 1661.5; 61/46.5 sensing signalling transmitters to maintain a predetermined weight on the drill bit during drilling operations [56] References Cited and to facilitate properly positioning, raising and low- UNITED STATES PATENTS ering of well bore and well head equipment, notwith- 2,949,038 8/1960 .lopson 192/51 standmg lmvemem of the floatmg barge vemFany by 2,950 086 8/1960 Abraham" 254,173 wave action. A reverse drive mechanism drives the 29771812 4/1961 Hoot 19251 hoist mechanism in a direction to allow downward 3,350,949 11/1967 Rapoza 192/51 movement of the drill g, w bore or well head 3,381,939 5/1968 Brown et a1. 254/172 equipment when the acceleration of the barge is so 3,469,821 9/1969 Gross et al 254/186 rapid that the supported weight does not overcome 3,550,735 12/1970 Olsen 192/51 the inertia of the drawworks 3,596,070 7/1971 McCool et al.... 235/151 3,624,783 11/1971 Chang 254/172 18 Claims, 9 Drawn: Figures U.S. Patent Nov. 4, 1975 Sheet 1 of 7 3,917,230

COOA/VT Sheet 2 of7 I 3,917,230

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US. Patent Nov. 4, 1975 Sheet40f7 -3,917,230

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US. Patent Nov. 4, 1975 Sheet 5 of7 3,917,230

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WELL DRILLING CONTROL SYSTEM BACKGROUND OF THE INVENTION In recent years it has become common practice to drill wells into the earth from floating or partially submerged barges or vessels which are anchored or otherwise held in place at the surface of the ocean or sea, at an offshore location. Such practice has involved procedures which are different and equipment which is different from the procedures and equipment used when drilling wells from a stable platform or from a landbased derrick, due to the inherent rise and fall of the vessel relative to the bottom of the sea or ocean floor.

In part, the problems of relative vertical movement of the floating vessel and the bottom of the sea or ocean floor have been alleviated by the development of underwater well head equipment. The use of such equipment involves setting a large casing or pipe in place in the ocean floor and attaching to such pipe a blowout preventer stack through which the well drilling string or pipe extends during the drilling operations, the pipe extending upwardly to the floating vessel or barge through the water. Thus, no relative vertical movement can take place between the blowout preventer and the well head, but the vessel and the drill string may move vertically with the waves, relative to the blowout preventer.

The problem of vertical movement of the drill string with the floating vessel is a problem which has been attacked by the use of bumper subs, which are specially constructed lengths of conduit telescopically engaged to enable the transmission of rotary movement to the drill bit from the drill string above the bumper sub. Bumper subs, however, are expensive and are a source of other problems such as leakage of drilling fluid and locking up so as to be no longer extensible, or other failure, which may cause improper drilling operations or shut down of the operations to enable repair or replacement of the bumper sub.

Customarily, when wells, such as oil or gas wells, are being drilled from a stable platform, say from a landbased derrick or a derrick which is supported fixedly on the ocean floor, well established drilling procedures are employed. In this connection, the weight of the bit on the bottom of the well bore is established by drill collars, which are heavy lengths of drill pipe located at the lower end of the drill string. The string of drill pipe extending upwardly from the drill collars to the kelly, which slidably engages in the kelly bushing rotated by the rotary table and is suspended by the hoist equipment in the derrick, may be many thousands of feet in length. Stating the matter simply, then, the total weight of the bit at the bottom of the well bore is the difference between the weight of the length of drill pipe which is supported in tension by the hoist equipment and the total weight of the drill string. Thus, the heavy drill collars are located at the lower end of the drill string and are relied upon to apply the desired weight to the bit, as may be determined by the nature of the subsuruface strata being drilled, both as to composition and angle, the condition of the bit, and the direction that drilling is progressing or is desired to progress. Such drill collars are also quite rigid and resist flexure or bending and may be stabilized in the well bore when desired.

Efficient drilling practice requires that the correct weight be maintained on the bit to produce the maxi- 2 mum correct drilling progress per unit of time. Control of the direction of drilling progress requires control of the weight on the bit. Thus, the weight on the bit should be fairly constant at aselected value, or the bit will be caused to wear excessively or the drill string may be deflected to an undesired angle, or drift from the desired angle.

Vertical movement of a floating vessel on which the drilling derrick and hoist equipment are mounted, however, causes vertical movement of the drill string, which with the usual equipment will cause changes in the weight of the bit, unless a bumper sub is employed and is properly telescoping. However, the bumper sub does not permit the weight on the bit to be changed, as may be required to improve the penetration rate of the drill or to cause the drilling direction to be changed or corrected, without round tripping the drill string to modify the drill collar weight below the bumper sub.

In addition, the vertical movement of the vessel or barge relative to the ocean floor poses problems of controlling the lowering of well head equipment, such as a blowout preventer stack, into position at the ocean floor. Such problems are caused because the vessel movement is superimposed on the motion of the equipment being raised and/or lowered relative to the ocean floor by the usual hoist equipment. I

In the treatment and logging of wells during completion or following completion, it sometimes becomes necessary to run into the well auxiliary equipment which must be located fairly precisely in the well bore and the position maintained during the treatment or the equipment must be moved at a predetermined rate. Well logging equipment, casing. perforating devices, well packers and formation testers are examples of such auxiliary equipment. In the use of the logging, perforating and testing equipment, the position must be maintained or known, but load or weight of the running in string is not significant. Vertical movement of the floating vessel renders difficult the effective application of the desired constant tension or weight to the running in string or the maintenance of a constant position of an auxiliary tool. 1

Efforts have been made to overcome such problems caused by the rise and fall of a floating vessel from which well drilling, completion and treating operations are performed by sensing the load of the drill string or tension of the supporting cable for the drill string and, in response to changes in load or line tension, varying or controlling the torque applied to the cable winding drum of the drawworks, in an effort to compensate for motion of the vessel in opposite vertical directions relative to the bottom of the water. However, such prior systems are relatively ineffective due to substantial inertia problems.

The drill string composed of heavy pipe may be long and have substantial weight and experience substantial friction in the well bore, between the neutral point and the hoist mechanism, resulting in the need for instantaneous sensing of changes in the vertical position of the vessel and correspondingly rapid correction or adjustment of the hoist mechanism, if the system is to be effective. On the other hand, when lowering the subsurface well head equipment, or raising the latter, and

when drilling at shallow depths, as well as when positioning treating or completing tools within the well bore, the inertia of the supported load and the hoist mechanism may be such that the rapid upward movement of the vessel is not instantaneously compensated for.

SUMMARY OF THE INVENTION The present invention involves the provision of hoist apparatus on a floating vessel with hoist controlling means whereby to compensate for vessel movement so that the load supported by the hoist equipment, either the drill string, running in string, or subsurface equipment being moved between the vessel and the ocean floor, does not experience the motion of the floating vessel caused by the rise and fall of the surface of the water.

The hoist mechanism of the typical drilling rig, including those on floating barges or vessels, comprises a derrick at the top of which is a crown block over which the fast line or working portion of a cable is reaved, the cable being also reaved on a traveling block. The working portion of the cable is taken up on and played out from the drum of a drawworks and the dead end of the cable is suitably anchored at the base of the derrick. The load, either the drilling string, well head equipment, or tool running string, to be lowered to the ocean floor or into the well bore is supported by a hook suspended beneath or otherwise connected to the traveling block. Thus, the present invention is directed towards controlling the hoist cable system in such a manner that the hook does not experience motion caused by vertical motion of the floating vessel, but only that motion which is caused by or allowed by the hoist system, so that the portion of the equipment supported by the hook or the load or weight on a drilling bit may be controlled and maintained constant.

In accordance with the present invention, the. weight on the bit or the load or tension on a running in string is maintained at a selected, constant value by sensing the load on the hoist mechanism. The position of well head or auxiliary equipment is maintained by sensing the movement of the barge or vessel relative to the stationary well site or riser pipe to produce signals which may be compared with signals produced by movement of the block to control the hoist equipment in such a manner that the movement of the vessel caused by wave action is compensated for to maintain the desired position or movement by compensating for vessel movement.

Inasmuch as the mass of the drawworks, the hoisting block, hook, drill string, or well bore or well head equipment is substantial, the present invention provides a hoist control mechanism and system which is capable of rapid response to changes in movement of the vessel and/or load changes, as the case may be, notwithstanding the substantial inertia of the system.

In addition, the invention provides a down-drive or reverse drive for the drawworks, whereby to positively assist in playing line off the drawworks drum, when the weight of the supported load would otherwise be insufficient to overcome the inertia of the drawworks and accelerate the latter to compensate for vessel movement.

In the practice of the invention, the drawworks drum is driven by a slipping drive, the torque transmitting capacity of which, in a selected automatic mode of operation, is varied in a manner determined by the load supported by the hook, or by the position of the hook or traveling block, relative to the barge or vessel, vertical changes in the position of the barge or vessel with respect to the sub-surface well pipe, and the speed and direction of actual rotation of the drawworks drum on and from which the load supporting fast line is wound and unwound. Also drivingly connected with the drawworks drum is a slipping reverse drive controlled by hook load or changes in the hook or barge position to drive the drawworks drum'reversely and overcome inertia when the barge or vessel accelerates rapidly upwardly faster than the load can cause acceleration of.

the drawworks drum.

The position sensing means preferably include position sensing devices according to the application of.

US. patent Ser. No. 127,892, filed Mar. 25, 1971, such devices being adapted to produce an output pneumatic signal which varies depending upon a change in the position of a motion sensing drive member. To operate these devices, sensing lines or cables are interconnected between both the traveling block or hook and a take-up reel on thebarge or vessel, or other counterweight means, and a sensing line is interconnected between a take-up reel on the barge or vessel or other counterweight means, and a fixed location such as the well pipe or riser beneath the water.

The slipping drive means for the drawworks drum.

has other purposes which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view generally showing a drilling rigon a I vessel afloat on a body of water and a well head at the bottom of the water through which well drilling, testing, completion and treating operations are conducted;

FIG. 2 is an enlarged diagrammatic view generally illustrating the hoist and control mechanisms of FIG. 1; 9

FIG. 3 is a plan view illustrating the drawworks apparatus;

FIG. 4 is a view partly in elevation and partly in section, showing a typical slip clutch for use in the main drum drive and the reverse drum drive of the apparatus;

FIG. 5 is a longitudinal section, showing a typical line position sensor for use in the control system to sense vertical movement of the vessel relative to the well head equipment and to sense movement of the traveling block relative to the vessel;

FIG. 6 is a longitudinal section, showing the computing pneumatic relay which compares the position responsive signals from the position sensors; and

FIGS. 7a through 70, together constitute a schematic diagram of the control system for the apparatus, FIGS. 7b and 7c being downward continuations of FIG. 7a.

DESCRIPTION OF THE PREFERRED EMBODIMENT As seen in the drawings, with reference first to FIG. 1, the present inventioninvolves the apparatus useful in the drilling, testing, completion and servicing of a well W which is being or has been drilled into the earth through the ocean floor F. On the ocean floor is well head equipment H through which the well drilling and other operations are conducted, and extending from the well head, upwardly towards the surface of the water is a so-called riser or outer pipe R, as is custom- The well drilling and other operations are conducted from a floating barge or vessel V, or from a semi-submerged platform, as is well known. On the barge or vessel V is a derrick D having a crown block C over which extends a line or cable L constituting the fast-line of the usual hoisting system, the line L being pulled in or let out, as may be necessary, by means of a drawworks DW. Supported by the line L is a combination of a traveling block and hook T adapted to support a drill string or other pipe string S which extends downwardly through the usual rotary table RT, through the riser R and the well head equipment H into the well W.

The problem solved by the present invention involves relative vertical motion between the vessel V and the well head H and relative vertical motion between the traveling block and hook H, and the combined vertical motion between the vessel V, the traveling block and hook T and the well head H. During a well drilling operation, to maintain a known constant weight on the bit, the traveling block and hook T is lowered by the drawworks at a rate determined by the rate of penetration of the drill bit through the earth, under the control of the driller who observes the usual weight indicator, but if waves or other water influences cause the vertical motion of the vessel to be superimposed on the traveling block and hook T, the drill string S will be correspondingly reciprocated vertically and alternately reduce and increase the weight on the drill bit, so that the drilling progress will be erratic. Likewise, if vertical motion of the vessel V is superimposed on the positioning of the traveling block and hook T, when well treating or completing operations are being conducted which require locating a sub-surface tool in the well, or when the well head equipment H is being positioned in place, the proper positioning of the tool or well head equipment will be difficult.

Accordingly, the present invention involves controlling the drawworks DW in such a manner as to compensate for the motion of the vessel so that motion of the vessel is not superimposed on the traveling block and hook T. When the weight of the pipe string S is substantial, say when drilling, motion compensation is accomplished by sensing the load on the traveling block and hook T and adjusting the drawworks DW to take up or play out the line L as may be necessary to maintain a substantially constant condition. When the load on the traveling block and hook T is relatively light, say, when running the well head H into position, when round-tripping drill pipe, or when positioning a tool in the well W, motion compensation is accomplished by sensing the position of the traveling block T relative to the vessel V and sensing the position of the vessel V relative to the well head H, and adjusting the drawworks to take up or let out the line L as may be necessary to maintain a substantially constant condition of position or rate of movement of the traveling block T.

Since the drawworks machinery is massive, and since under some conditions of load on the line L and motion of the vessel V, the load cannot overcome the inertia of the drawworks sufficiently rapidly to pull line L therefrom during upward movement of the vessel V, the present invention involves, also, positively driving the drawworks in a reverse direction when necessary, to overcome inertia and reversely accelerate the motion of the line L at a rate corresponding substantially to the rate of upward movement of the vessel V.

Referring more particularly to FIG. 2, the apparatus will be seen to comprise load sensing means LS for sensing the load on the traveling block hook combination T. This load sensing means, in the illustrative embodiment is incorporated in the crown block C, by interposing a hydraulic load cell 1 between a lower fixed portion 2 and an upper movable portion 3 of the crown block support. The traveling block movement is sensed by a sensing line 4, suitably connected to the traveling block T and extending over a pulley 5 rotatably supported on the crown block support. This sensing line 4 is engaged with the traveling block movement sensing means TS, later to be described in detail, which is located at a convenient out-of-the-way location, the line 4 being wound on or unwound from take-up reel means 6. This take-up reel means, without need for further illustration or description, may be a simple spring rewound reel adapted to maintain the line 4 taught for engagement with the sensing means TS. Vertical movement of the vessel V relative to the well head H is sensed by vessel movement sensing means VS, corresponding to the sensing means TS, as will be later described. This sensing means VS is operated by a sensing 7 line 7 connected at 8 to a fixed location, specifically the riser pipe R which is a fixed upward extension of the well head H. The sensing line 7 engages the vessel movement sensing means VS and is wound on and unwound from take-up reel means 9 of the spring rewound type to maintain the sensing line 7 taught. Adjacent to the drawworks DW in a position convenient to the driller, is a control panel 10, from which the apparatus can be controlled and monitored in the manner hereinafter to be described, so. that the drawworks, now to be described, will be operated to pull in or play out the fast line L under the control of the load sensing means LS or under the control. of the traveling block position sensing means and the vessel position sensing means VS, and the related; regulating system hereinafter to be described, or under manual control.

Referring to FIG. 3, the drawworks DW is generally illustrated. Since under some conditions, say while drilling a deep well, the drawworks must support an extremely heavy string of drillpipe and drill collars, and since, in the motion compensating mode of operation, the entire load of the drill string or other load supported by the traveling block and hook T must be accelerated upwardly rapidly, the power system for the drawworks DW is selectively operable to utilize more or less of a plurality of prime movers or motors M. Electric motors M are preferred and are suitably mounted on the floor of the derrick outwardly spaced from the drawworks drum 11 with respect to the rotary table RT.

Without requiring illustration in detail of the various supporting means, the drum 11, on which the fast line L is wound is fixed on a rotatable shaft 12 on suitable bearings 13. At the opposite outer ends of the drum shaft 12 are left and right hand slip clutches SC, the details of which will be later described.

The slip clutches SC are adapted to drive the drum in a direction to wind the line L on the drum-or to allow the line to be played off of the drum, depending uponthe adjustment of the torque transmitting capacity of the slip clutches. Drive means for the slip clutch SC at the right hand side of the drum 11 include the right hand three motors M which through the usual drive chains 14R and sprockets drive a countershaft 15R. This countershaft 15R is selectively drivingly connectable through chains 16R and sprockets of different drive ratios to a right hand transmission shaft 17R, the respective drive chains 16R and their sprockets on the transmission shaft 17R being selectively coupled to the latter by suitable clutches 18R, so that the transmission shaft 17R can be driven at any of the three selective low, intermediate and high ranges. The transmission shaft 17R drives a chain 20R which engages the drive sprocket 21R of the right hand slip clutch SC to transmit rotation through the clutch to the drum shaft'l2.

correspondingly, the left hand slip clutch SC is driven by the left hand three motors M by means of left hand drive chains and sprockets 14L, a left hand countershaft 15L, transmission chains 16L and companion transmission sprockets, connected to the transmission,

shaft 17L by selective clutches 18L, to drive the drive chain 20L for the left hand slip clutch sprocket 21L. It will be understood, withoutrequiring specific illustration, that the right hand and left hand drives for the drum 11 can be controlled and operated in unison, and that the transmission means enable high speed drum rotation to low speed rotation at a range of load capacity which will enable the drum L to hoist the substantial weight encountered during the well drilling and other operations, at a rate equal to the desired movement of the traveling block and hook combination T, plus the vessel movement in a downward direction, under the control of the slip clutches SC which drive the drum and which are in turn adjusted, as required, by means of this system and according to the method hereinafter described.

However, when the .vessel V moves upwardly at a rapid rate, the drawworks DW, as thus far described, must also allow the fast line L to play off of the drum 1 1 at a rate equal to the desired motion of combined traveling block and hook T, plus the movement of the vessel. Even though the control system, later to be described, may be capable of quickly controlling the slip clutches SC to minimize the torque transmitting capac-. ity of the clutches, so that the drum 1] is relatively free, the mass of the drum 11 in the usual drawworks is so great that the inertia may not be overcome by the supported load sufficiently rapidly to enable full compensation for the vessel movement. The steeper the incline of an ocean wave and the more rapid the rate of travel of the wave, the greater the acceleration problem.

Accordingly, in accordance with the invention, the present drawworks, also includes a reverse drive means RD for the drum 11, whereby to overcome the inertia of the drum and accelerate it as may be necessary, to fully compensate for the vessel movement upwardly, so that such upward motion will not be superimposed on the desired motion of the load supported by the traveliii' g block and hook T.

reverse drive means RD, as specifically illusarea, is driven by the right hand transmission shaft 17R, but, if preferred, may be otherwise driven, saybe a separate power source; Since the transmission shaft 17R is shown as the input drive shaft, the reverse drive DR has a reversing gearset 22 to drive a reverse drive output shaft 23 oppositely" from the shaft 17R. Driven 1 by the output shaft 23 is another slip clutch SC corre- I sponding, in general, with the clip clutches SC which drive the drum shaft 12, but of smaller size, sincethe torque capacity of the reverse drive means RD need not be as greatas the torque capacity of the drum drive. The output of the. slip clutch SC of the reverse drive means RD is connected by. a drive chain 24 and companion sprockets to the drum shaft 12 to drive the lat--' ter in the reverse direction when the drum slip clutches SC are comparatively disengaged under the control of the motion andloadsensing means, later to be described, but when the drum slip clutches SC are engaged to wind in the fast line L, the slip clutch SC of the reverse drive means is. comparatively released.

Various slipping drives may be employed at the locations of the respective slip clutch means, or otherwise, but preferably the slipping drives comprise slip clutches 33 on bearings 33a. Affixed to the sprocket 21, is a disc 34 which is in turn affixed by fasteners 35 to the outer periphery of the back-up plate 36 of the slip clutch means SC.

The slip clutch means SC includes an outer annular body 37 to which an annular flange 38 is connected by fasteners 39 in opposed relation to the plate 36. lnternally thereof, the body '37 has a splined connection 40 with the outer periphery of an axially shiftable clutch f pressure plate 41.-Between the clutch plates 36 and 41 is a clutch friction disc 42 having friction facing 43 on opposite sides thereof and having, as at 44, a splined connection with a hub 45 which is disposed upon the shaft end 33 and is keyed thereto by a key 46. Thus, ro-

tation from the sprocket 21 will be transmitted to the drum shaft 12 when the slip clutch means SC is engaged to transmit rotation from the clutch body 37 and its plates 36 and 41 to the friction disc 42.

Engagement of the slip clutch means SC is accomplished by an annular expansible actuator tube 47 having an air inlet 48. The actuator tube 47 engages an annular body of insulating material 49 interposed between the tube 47 and the clutch pressure plate 41. Each of the clutch plates 36 and 41 has a number of annular, radially spaced and concentric coolant passages 36a and 41a to which a coolant is supplied to dissipate the heat of friction caused by slippage of the clutch SC.

These passages 36a and 41a are defined respectively by the plate 36b and a wear disc 41b carried by the plate 41, the friction material on the friction disc 42 being engaged with the wear discs 36b, 41b.

Such cooled, slip clutches are well known, and generally are provided with'a coolant circulating system including astationary coolant" connector 51 through which coolant flows toand from a rotary connector 52 which is connected, as by fasteners 52a, to the clutch flange 38 and whichhas conduit means 53 for supplying coolant to the passages 36a-and 410, as well as conduit means for the returriflow of coolant to the connec- 9 tor 51 and thence to a heat exchanger. Preferably, in order to more effectively cool the clutch, it is constructed in accordance with the aforementioned application for patent. In addition, the rotary connector 52 provides a connection for air conduit means 54 which leads to the air inlet 48 for the clutch actuator tube 47 from a stationary air inlet fitting 55. As is well known, the torque transmitting capacity of such slip clutches varies with the pressure of air in the actuator tube 67.

Thus,'the tension applied to the line L will be determined by the magnitude of the air pressure supplied to the actuator tube 47 through the coupling 55 of the respective slip clutches under the control of the system to be more fully described below.

The typical and preferred line position sensing means VS and TS is shown in greater detail in FIG. 5. It comprises an elongated housing 81 having at one end a closure or cap 82 and having at the other end an assembly which provides an air inlet or supply port 84, an outlet 85 for a controlled air pressure signal, a port 86 for bias pressure fluid, and a port 87 communicating with the atmosphere.

Included within the assembly are actuator means generally denoted at 88, fluid pressure responsive piston means 89 operatively connected to the actuator means 88, orifice means 90 operable in response to the application of fluid pressure to the piston means 89 and to the application of force from the actuator means 88 for opening and closing the orifice means 90, and combined inlet and outlet valve means 91 for controlling the flow of air from the supply port 84 to the outlet port 85 and for controlling the exhaust of air from the outlet port 85 to the atmosphere through the port 87.

In general, it is the purpose of the position sensing pneumatic control device to regulate the output signal pressure to a constant value which is determined by the net force applied to the piston means 89, whereby the orifice means 90 is either opened or closed for a period sufficient to balance the piston means 89, so that the pressure drop through the orifice means 90 remains constant, resultingn in a constant output signal pressure at the port 85 which leads to the computer relay or transmitter, as will be later described.

More particularly, the actuator means 88 comprises a shaft 92 which extends longitudinally of the housing 81 and has an end cap 82 through a suitable bearing 94 and a suitable seal 95. Disposed upon the shaft 92 within the housing 81 is a spring seat 96 having a reduced central section 97 on which is piloted the upper end of a coiled compression spring 98. The shaft 92 is threaded as at 99, and the spring seat 96 and the reduced pilot portion 97 thereof are complementally threaded, whereby rotation of the shaft 92 will effect longitudinal movement of the spring seat 96 on the shaft, since the seat 96 is held against rotation by a key 100 carried thereby and extending into a lateral slot 101 in the housing 81. At its inner end, the spring 98 seats on a spring seat 103 having a reduced pilot portion 104. This spring seat 103 is connected by fasteners 105 to the circular upper body portion 106 of the piston 107 of the piston means 89, the seat 103 and the body 106 being held in axially spaced relation by tubular spacers 108 interposed therebetween and through the fasteners 105 extend. The lower end of the shaft 92 extends through the seat 103 and is journalled in a bearing 109 which is mounted in a supporting spider 110 having circumferentially spaced openings 111 to 10 accommodate the spacers 108, whereby the piston means 89 is axially movable.

The assembly also comprises, in addition to the spider 110, an annular spacer 112, an annular cylinder 113 for the piston 107 and an annular cylinder 114 which houses a piston 115, an annular body 116 containing the nozzle means 90, and an end member 117. The spider 1 10, spacer 112, cylinders 113 and 114, annular body 116, and end member 117 are interconnected together and to the cylindrical body 81 by tiebolts or the like, requiring no illustration.

Between the spacer 112 and the cylinder 113 is clamped the outer marginal portion of a diaphragm 119, and between the cylinder 113 and the cylinder 114 is clamped the outer marginal portion of another diaphragm 120. Still another diaphragm 121 has its outer marginal portion clamped between the cylinder 114 and the annular body 116. In the illustrative embodiment, the upper body portion 106 of the piston 107, the piston 107 and the piston are interconnected by a stern 122 having an enlarged head 123 at one end which clamps the inner periphery of the diaphragm 121 against the adjacent portion of the piston 1 15, and a nut 124 is threaded onto the other end of the stem 122 to effectively clamp the piston 107 and its upper body portion 106 together. The inner periphery of the diaphragm 119 is like-wise clamped between the upper body portion 106 and the piston 107, and the inner periphery of the diaphragm is clamped between the piston 107 and the piston 1 15. Thus, the piston means 89 comprises both the piston 107 and the piston 115.

More particularly, the piston 107 has an enlarged portion 125 which is exposed to the pressure in a chamber 126 provided in the cylinder 113 between the diaphragms 119 and 120. The piston 115 is exposed to the pressure in a chamber 127 provided in the annular body 116 across substantially the entire cross-sectional area of the piston 1 15. Within the cylinder 1 14, the piston 115 is disposed in a chamber 128 which is vented to the atmosphere through radial ports 129.

Interposed between the annular body 116 and the end member 117, and clamped at its outer margin is a double diaphragm assembly including an upper diaphragm 130 and a lower diaphragm 131 spaced apart by an outer marginal spacer 132 in which is formed one or more of the radial ports 87, previously referred to, which communicate the space between the diaphragms 130 and 131 with the atmosphere. In the annular body 116 above the upper diaphragm 130 is a chamber 134 and centrally of the body 1 16 is a threaded bore having therein a nozzle 136 of the nozzle means 90, the port through which communicates with the chamber 134, and the outlet of which is opposed by a nozzle seat 137 suitably carried by the lower end of the stem 122. Air is supplied to the chamber 134 and thence to the nozzle 136 from the supply port 84 through a passage 138 which extends through the margin of the diaphragms 130 and 131 and the spacer 132 and connects with a passage 139 leading into the chamber 134. Disposed in the passage 139 is a flow restrictor 140 having a reduced passage therethrough. This flow restrictor is replaceable through an opening in the body 116 which is closed by a threaded closure plug 141 At the outer side of the diaphragm 131 in the end member 127 is a chamber 142 which communicates with the outlet port 85. The outlet port 85 also communicates through a 1 1 passage 143 with the chamber 127 in the body 116 below the diaphragm 121.

The inlet and outlet valve means 91, previously referred to, includes a valve seat 144 carried by a plate 145 below the diaphragm 131 and having a valve port 146 leading from the outlet chamber 142 into the space between the diaphragms 130 and 131. A coiled compression spring 145a is provided, beneath the plate 145 which applies a normal inward bias to the diaphragm 131 and to the outlet valve seat 144. A valve stem 147 is reciprocably mounted in a port 147a in the end member 117, which port leads from the inlet 84 to the outlet 85. The stem is normally biased inwardly by a coiled compression spring 148 which seats in a plug 149 in the end member 1 17 and acts inwardly on a spherical valve head 150 to bias the same against an inlet valve seat 151.

As previously indicated, the position sensing pneumatic control device functions to regulate the output signal pressure at the port 85 to a value which is proportional to sensed movement. Accordingly, the outer end 93 of the shaft 92, in the illustrative embodiment, has mounted thereon the sheave or roller 152 which is engaged by the sensing cable or line 4 or 7, of the sensing means VS and TS, to effect rotation of the shaft 92 in response to relative movement between such line 4 or 7 and the sensing unit. The sheave or roller 152 is of such diameter that maximum line motion will not cause rotation beyond the adjustment limits of the screw shaft 92. Alternatively, a reduction gear means may be employed to reduce the rotation of the shaft 92 per revolution of the sheave 152. Movement of the sensing line is transmitted to the shaft 92 to effect rotation of the latter in one direction or the other depending upon the direction of movement of the line 4 or 7, which depends on the direction of relative movement of the load and the vessel. It is apparent that rotation of the shaft 92 in one direction or the other will impose more or less compression on the spring 98 to provide more or less force acting on the piston means 89 which will either cause the nozzle seat 137 to close the nozzle 136 or to open the nozzle 136 for communication with the chamber 127, and hence the discharge or signal output port 85. Such spring force is opposed by the pressure of air in the chamber 127 acting on the cross-sectional area of the piston 115 and the pressure of fluid in the chamber 126 acting on the effective area of the piston 107. Thus, the fluid admitted through the port 86 to the chamber 126 may be supplied from a remote set point to modify operation of the sensing unit so that the signal output pressure is at a desired level, as will be later described, or the chamber 126 may be exposed to atmosphere.

With the foregoing details in mind, the operation of the motion sensor is such that the spring 98 is operative to apply a variable force in a direction tending to move the piston means 89 downwardly. Opposing the force derived from the actuator means is the force derived from the application of pressure either atmospheric or from a remote set point to the bias chamber 126, which pressure is effective over the area of the enlargement 125 of the piston means 89 to provide a force tending to move the piston means 89 upwardly. Also providing a force tending to move the piston means 89 upwardly is the pressure in the piston chamber 127 which acts upon the piston 115 of the piston means 89, the other side of the piston 115 being exposed to the atmosphere in the chamber 128.

rows, into the piston chamber 127. When the device is. in the condition shown in FIG. 5, the effective signal outlet pressure at the outlet is the same as that in the piston chamber 127, and under the condition shown the pressure at the outlet 85 will remain constant, un-

less the force derived from the actuator means 88 is varied, or the force derived from the remote set point pressure is varied, as will be later described.

Assuming that the force derived from the actuator means tending to shift the piston means 89 downwardly is reduced, the net force acting on the piston means will cause the piston means to move upwardly, allowing greater flow from the pilot pressure chamber 134 into the piston chamber 127. Such action will result in an instantaneous decrease inthe pivot pressure in the chamber 134. As a consequence, pressure applied to the diaphragm 131 and the force of the spring 145a will move the exhaust valve seat 144 upwardly away from the end of the valve stem 147, to allow the greater exhaust of fluid pressure from the outlet chamber 142 and the piston chamber 127 through exhaust port 87, until the device again assumes the condition shown in FIG. 5 at which valve means 91 is at equilibrium and the necessary volume of air is permitted to flow through the port 146. At this time, the pressure at the outlet 85 will again be stabilized at a value determined by the fluid pressures acting on the actuator means 88 and the decreased spring force of the spring, and the signal outlet pressure will be at a lower value.

Assuming that the force derived from the actuator means tending to move the piston means 89 downwardly is increased, overcoming the effect of the signal outlet pressure in the chamber 127, then the orifice closure disc 137 will engage the end of the orifice means 136, thereby shutting off the passage of air from the pilot pressure chamber 134 into the piston chamber 127. Under these circumstances, the pilot pressure in the pilot chamber 134 will build up, forcing the diaphragm 130 and the diaphragm 131 downwardly,

thereby unseating the valve 150, so that inlet pressure will transfer through port 147a of the inlet-outlet valve means 91, resulting in an increase in the signal outlet pressure in the outlet chamber 142 and in the piston chamber 127 which will be effective to again condition the apparatus as shown in FIG. 5, so that the pressure at the outlet 85 again remains constant, but greater.

It will now be understood that variation of the remote set point pressure in the chamber 126 will have the same effect as variation of force derived from the actuator means. In other words, as the remote set point pressure is increased, the force tending to move the piston means 89 upwardly will also be increased, but if the remote set point pressure is decreased, the force tending to move the piston means 89 upwardly will be de-. creased.

The supply of air to the chamber 126 of the sensing unit of the vessel or reference position sensing means VS, through the port 86 is shown in FIG. 7a, as being via a conduit 86a leadingfrom a suitable valve 86b which controls the pressure derived from a source conduit 86c which leads from a suitable pressure source, not shown. The outlet port 85 is in communication with a conduit 85a which leads to a computer relay or pressure transmitter CR, hereinafter to be described. On the other hand, the chamber 126 of the sensing unit of the load position or traveling block position sensing means TS, communicateswith atmosphere through the port 86, unless a bias pressure other than atmosphere pressure is desired to modify the operation of the system. In any case, the outlet 85 of this sensing unit is connected by a conduit 85b to a proportional controller, later to be described, and to the computing relay or transmitter CR.

The computer relay or transmitter CR is provided to compare the position signals received from the position sensors VS and TS and another signal representing drum speed, as will be later described, to produce a resultant output control pressure signal. As seen in FIG. 6, the computer relay CR comprises a support 200 adapted to be mounted at a suitable location. Carried by the support 200 is an end cup 201 having a marginal flange 202 for connecting the cup 201 with an assembly which comprises a stack of discs 203, 204, 205, 206 and 207 and a body 208, all connected at the outer peripheries by a suitable number of tie bolts, one of which is shown at 209. The disc 203 includes a rigid central section 203' and a flexible annular diaphragm 203" supporting the central section. Each of the discs 204, 205, 206 and 207 correspondingly comprises a rigid central section 204 to 207 and an annular diaphragm 204" to 207". Intermediate, the discs 203 to 207 are annular, outer peripheral spacers 210 and central spacers 211. The outer spacers 210 are connected in the assembly by the tie bolts 209. The central spacers 211 are interconnected at the respective central sections 203 to 207 by a pin 212 having a head 213 at its lower end and a nut 214 at its upper end for clamping the central disc sections and central spacers together.

Air under pressure is supplied to the computer means CR above and below the stack of diaphragms and be tween the diaphragms from various sources, whereby to provide an output pressure signal which is a function of the various input signals and the constant force of an adjustable coiled spring K which is disposed in the cap 201 and seats, at one end, on a seat 215 above the disc section 203 and, at the other end, on a spring seat 216 carried by an axially shiftable adjuster pin 217. The pin 217 is shiftable by an adjuster screw 218 threaded in a nut 219 which is suitably affixed to the support 200. Below the disc 207 is anofller coiled spring K which seats at one end in a seat 208' and engages at its other end beneath the disc section 207' in opposition to the spring K. Thus, the spring K is adjustable to provide a selected force on the stacked disc sections 203 to 207, determined by the relationship between springs K and K.

Air pressure is supplied to a chamber VSl in the cup 201, from the vessel reference position sensing means VS via conduit 85a, by suitable means, such as an inlet fitting 220, to provide a downward force on the effective piston area of the central section 203' of disc 203. In order to increase the magnitude of the force derived from air pressure supplied to the computer CR from this position sensor means via conduit 85a, a branch conduit from conduit 85a leads to a chamber VS2 defined between the diaphragms 203" and 204", say through a pressure inlet 221, so that such pressure also acts downwardly on the effective annular piston area of the central section 204' of the disc 204, which extends radially beyond the spacer 211 thereabove.

Below the annular piston area of the disc section 204 is a chamber TS having an inlet 222 to which pressure fluid is supplied, via conduit b, at a value determined by the load or traveling block position sensing means TS, the pressure in chamber TS acting upwardly on the effective annular piston area of the disc section 204 in opposition to the downward force derived from pressure in the chambers VSl and VS2.

Between the discs 205 and 206 is defined a pressure chamber A to which air is supplied through an inlet 223 via a conduit 223a, at a pressure determined by the speed of rotation of the winch drum, under the control of a speed responsive means, as will be hereinafter described. The disc section 206' provides an annular piston area projecting radially outwardly of the spacer 211 thereabove, this piston area being responsive to pressure in chamber A to provide a downward force. Below the disc section 206' is another chamber B exposed via a port 224 to atmosphere but to which air may be supplied at some other pressure, if desired, representing load on the line L. Such pressure acts upwardly on the effective annular piston area of the disc section 206.

Below the disc 207, and in the body 208, is a chamber X which constitutes an output chamber communicating with an outlet port 225 via porting 226. The pressure in the chamber acts upwardly on the lower disc section-207', and this pressure is derived from an inlet conduit 227a connected to an inlet port 227, and under the control of the computer CR, an output signal is transmitted to control the system, as will be later described.

Interposed between the body 208 and an end member 228 having the ports 225 and 227 therein, and clamped at its outer margin, is a double diaphragm assembly 229 including an upper diaphragm 230 and a lower diaphragm 231 spaced apart by an outer marginal spacer 232 in which is formed one or more radial outlet ports 232a, which communicate the space between the diaphragrns 230 and 231 with the atmosphere. In the body 208 above the upper diaphragm 230 is a threaded bore having therein a nozzle 236, the port through which communicates with the chamber X, and the outlet of which is opposed by a valve head 237 suitably carried by the lower end of the stern 212. Air is supplied to the chamber 234 and thence to the nozzle 236 from the supply port 227 through a passage 238 which extends through the margin of the diaphragms 230 and 231 and the spacer 232 and connects with a passage 239 leading into the chamber 234. Disposed in the passage 239 is a flow restrictor 240 having a reduced passage therethrough. This flow restrictor is replaceable through an opening in the body 208 which is closed by a threaded closure plug 241. At the underside of diaphragm 231 in the end member 228 is a chamber 242 which communicates with the output port 225. The output port 225 also communicates through the passage 225, previously referred to, with the chamber X in the body 208 below the piston or disc section 207.

Inlet and outlet valve means are provided to control the admission of fluid from the inlet 227 to the chamber 242 and the exhaust of such fluid through the vent port 232a. This valve means includes a valve seat 244 carried by a plate 245 below the diaphragm 231 and having a valve port 246 leading from the outlet chamber 242 into the space between the diaphragms 230 and 231. A coiled compression spring 2450 is provided beneath the plate 245 and applies a normal upward bias to the diaphragm 231 and to the outlet valve seat 244.

A valve stem 247 is reciprocably mounted in a port 247a in the end member 228, which port leads from the inlet 227 to the outlet chamber 242. The stem is normally biased inwardly by a coiled compression spring 248 which seats in a plug 249 in the end member 228 and acts inwardly on a spherical valve heat 250 to bias the same against an inlet valve seat 251.

As previously indicated, the computer means CR functions to regulate the output signal pressure at the port 225 to a value which is proportional to the input signals from the sensing means VS and TS, as well as the input signal representing speed of the drum 1 1, and in addition, the computer may be adjusted to modify the output pressure by varying either the effective constant force of spring K or the reference set point pressure in the chamber B. Thus, as will be understood, the output pressure in chamber X is determined by the various pressures in the various chambers VSl, VS2, TS, A and B, acting on the various piston areas of the discs 203 to 207. The equation may be stated:

where VS 1 and VS2 are the pressure derived from the vessel position sensing means VS tending to close the nozzle 236, TS is the pressure'derived from load position sensing means TS tending to open the nozzle 236, A is the pressure derived from the speed of the drum 1 l tending to close the nozzle 236, B is the atmospheric pressure tending to open the nozzle 236, and K is the spring constant.

The effective signal outlet pressure in the outlet chamber 242 is a function of the reduction in the inlet pressure caused by the passage of air from the inlet 227 through the flow restrictor 240 into the pilot pressure chamber 234, and the reduction in pressure resulting from the passage of air from the pilot pressure chamber 234 through the orifice means 236, as indicated by the arrows, into the pressure chamber X. When the device is in the condition shown in FIG. 6, the effective signal outlet pressure at the outlet 225 is the same as that in the chamber X, and, under the condition shown, the pressure at the outlet 225 will remain constant, unless the force derived from any of the position sensing means VS or TS, drum speed, or the reference pressure at chamber B is varied, and, accordingly, as will be later more fully described, the actuating pressure supplied to the clutches SC which drive the drum 11 will remain constant.

Assuming that the force tending to shift the stacked disc section causes the valve head 237 to move upwardly allowing greater flow from the pilot pressure chamber 234 into the chamber X, such action will result in a decrease in the pilot pressure in the chamber 234. As a consequence, pressure applied to the diaphragm 231 and the force of the spring 245a will move the exhaust valve seat 244 upwardly and off of the end of the valve stem 247 to allow the exhaust of fluid pressure from the outlet chamber 242 and the chamber X through exhaust port 232a between the diaphragms 230 and 231, until the device again assumes the condition shown in FIG. 3 at which the exhaust valve port 246 is again closed. At this time, the pressure at the outlet 225 will again be stabilized at a lower value, determined by the change in forces acting on the stack of disc sections 203 to 207.

Assuming that the net force tending to move the stacked discs 203 to 207 downwardly is increased, overcoming the effect of the signal outlet pressure in '16 the chamber X, then. the orifice valve 237 will close the orifice means 236, thereby shutting off the passage of air from the pilot pressure chamber 234 into the chamber X. Under these circumstances, the pilot pressure in the pilot chamber 234 will-build up, forcing the diaphragm 230 and the diaphragm 231 downwardly,

thereby unseating the valve 250, so that inlet pressure will transfer through port 247a of the inlet-outlet valve means, resulting in an increase in the signal outlet pressure in the outlet chamber 242 and in the chamber X, which will be effective to again condition the apparatus as shown in FIG. 6, so that the pressure at the outlet 225 again remains constant, but greater.

The controlling system of FIGS. 7a through 7c will now be described. At this point, it will be understood that the pressure in the chambers VSl and VS2 of the computing relay CR is determined not only by the position of the sensing line 7, resulting in the transmitting of r a pressure from the sensing unit of the vessel portion sensing means VS to the chambers VSl and VS2 related to position sensing line movement, but also by the variable pressure in chamber 126 of this sensing means VS supplied via conduit 86a, resulting in more or less force applied to the piston means 89 to oppose the force of the spring 88. Thus, by manipulating the supply valve 86b, the outlet signal pressure supplied from the unit of the position sensor VS, is adjusted to modify the outlet signal pressure in the chamberX of the computing relay CR, so that the signal supplied from the latter is varied to adjust the drum clutches SC and move the load or allow the load to move relative to the vessel V. Y

The output signal of the computer CR is also, as pre-. viously indicated, variable by the speed of the rotation of the drum 11. Thus, a pneumatic speed sensing transmitter device AS is driven by the drum 11, and produces at an outlet conduit 223a a signal derived from a source 223b, of a magnitude determined by winch speed. Such pneumatic transmitters are well known and may be a Foxboro Type 16A. Such output signal is applied through the conduit 223a to the inlet 223 of the computer CR and into chamber A.

A conduit 300 leads from the outlet port 225 of the More particularly, the controller PC may be Model I 50 Controller of Moore Products Co.,,of Spring House, Pennsylvania, or a Model 2516 Controller of Fisher Governer Company of Marshalltown, Iowa, as exam-. ples, the controller, generally shown in FIG. 7b, being the latter and more specifically illustrated in Bulletin D-2506A of that company.

The controller PC is supplied a reference pressure at an inlet 304 from the conduit b connected to the outlet from the sensing unit of the load or traveling block position sensing means TS, the same reference pressure being suppliedto the chamber TS of the computer or. transmitter means CR. The-pressure signal from the. chamber X of the computer. CR is admitted to a bellows 3070f the controllerPC which acts downwardly on a plate 308. Pressure supplied to the inlet 304 from the load position sensing means TS causes an increase in pressure in a bellows 309 which is opposed to the bellows 307 and acts upwardly on the plate 308. The posi- 7 tion of the plate 308 relative to a nozzle 310, to which controlled fluid pressure is supplied from they source inlet 303, is determined by the difference in pressures in the bellows 307 and 309. If the output pressure from the load position sensing means TS increases, the pressure increases in bellows 309 causing the plate 308 to move closer to the nozzle 310, restricting flow through the nozzle to cause an increase in the pressure in a chamber 311 of a control valve 312, causing an increased downward force on a diaphragm assembly comprising spaced diaphragms 313 and 314, which carries a valve seat 315, the passage through which communicates with the atmosphere through a port 316 between the diaphragms 313 and 314. The valve seat 315 engages and pushes downwardly, under the circumstances now being described, on an inlet and outlet valve having a head 317 for closing the exhaust passage through the valve seat 315 and a head 318 which is moved away from a seat 319 to allow increased supply pressure into the valve outlet chamber 230 which acts on the diaphragm 314 until the valve seat 315 is again moved upwardly to allow return upward movement of the inlet-outlet valve head 318 towards its seat.

During the same time that pressure is increasing in the chamber 320, such pressure is supplied to the outlet 302, and, thus, to the clutches SC for the drum 11 via a conduit 325, as well as to an adjustable proportioning valve 321, in the controller TC, and, depending on the adjustment of the latter, to an adjustable re-set control valve 322 which controls the build up of pressure in a bellows 323. This bellows 323 acts downwardly on the plate 308 tending to move the latter away from the nozzle 310 to decrease pressure at the outlet 302 and in control valve chamber 320, and is opposed by the upward action of a bellows 324 to which pressure is supplied from the valve 322 at a slower rate, depending on the adjustment of the valve 322, until the plate 308 is moved toward the nozzle to again increase pressure at the outlet 302 and in the valve chamber 320.

If a change in the system causes a decrease in pressure at the inlet 304 to the controller PC, then, the reverse action will occur in the controller, the tendency being in either case to attempt to return to a pre-established, constant pressure at the outlet 302, which pressure is a function of the outlet pressure from chamber X of the above-described computer means CR and the signal pressure from the load position sensing means The outlet pressure from the controller means PC is supplied via the conduit 325 to cause actuation of the clutches SC for the drum 11, but preferably a typical booster 326 is employed, whereby the actual pressure source (not shown) for the clutches includes an inlet to the booster 326 from a relatively high pressure source and the pressure in conduit 325 acts on the usual pilot valve of the booster, so that the outlet 328 of the booster is at a greater pressure than the signal pressure from the controller PC. In addition, it is preferred that a selector valve 329 be provided, so that the air connector 55 of the clutches SC for the drum 11 may be connected either to the booster outlet 328 or, altematively, to a separate source conduit 330 including a manual control valve 330a for operating the clutches SC to drive the drum 1] independently of the control system.

For convenience, a gauge panel G is preferably provided, as seen in FIG. 7a, whereby to indicate the effective pressures determined by the vessel motion sensing line and load position line sensing means VS and TS, respectively, and the ultimate clutch actuating pressure supplied to the slip clutches for the drum 11, such gauges being designated by the legends VES. POS.. LOAD POS., and DRUM CLUTCHES.

The VES. POS. gauge is connected to the output of the position sensing means VS by a conduit 400 which joins with the conduit a leading to the computer chambers VS1 and VS2. The LOAD POS. gauge is connected by a conduit 401 to the conduit 8512 which leads to both the inlet 304 of the controller PC and to the chamber TS of the computer or transmitter CR. The DRUM CLUTCHES gauge is connected by a conduit 406 with the respective air inlet connectors 55 of the clutches SC for the drum 11 and the outlet 328 of the pneumatic booster 326. Other gauges may be employed if desired to show other pressures, such as the pressure derived from the speed of the winch, and the bias pressure supplied to the sensing means TS.

From the foregoing, it is clearly believed that the operation of the present invention, as thus far described, involves the controlling of the slip clutch drive means for the winch drum 11 to apply a tension to the line L, controlled such that the tension is maintained substantially constant at a value established by the bias pressure supplied to the bias chamber 126 of the reference position sensing means VS1, but the air pressure supply to the clutches SC for the drum 11 is, in the automatic mode, controlled by changes in load line 4 position or vessel line 7 position sensed by the sensing means TS and VS, respectively, whereby, when the vessel V moves relative to the well head H, a reference signal proportional to the movement is supplied in the chambers VS1 and VS2 of the computer CR, varying the output signal pressure in the chamber X of. the computer which is transmitted to the inlet 301 of the proportional controller PC, which varies the actuating pressure supplied to the actuators of the clutches SC for the drum 1 l, to cause the load to move, thus operating the load position sensing means TS until a change in the pressure supplied to chamber TS of the computer CR equals the pressure change caused by movement of the vessel position sensing means VS. Thus, the load is caused to move substantially synchronously with the vessel V, unless the bias pressure supplied to the chamber 126 of the vessel position sensing means VS is varied at the valve 86b, to move the load in one direction or the other relative to the vessel V, so long as the weight of the load can overcome drawworks inertia when the vessel moves upwardly.

The speed signal pressure transmitted to the chamber A of the computer means CR is selected at some constant value when the winch is stationary, and the speed responsive means AS produces an increasing pressure signal as the velocity of the load increases upwardly and a decreasing pressure signal as the velocity of the load increases downwardly. During load movement, the transmitter AS continuously supplies a changing pressure to the chamber A of the computer CR, which changes the computer output signal to the controller PC to assist in controlling overshooting the end points of the load motion. In addition, the doubling of the effect of the reference line position pressure signal supplied to the computer means CR in a pair of chambers VS1 and VS2, causes the signal supplied to the control- 19 ler PC to be greater than would be the case if the signal to the controller at the reference inlet 301 were supplied directly from the sensing means TS.

It will also be understood, that if load control is desired, to limit load on the drawworks, a load responsive signal may be transmitted to the chamber B of the computer means CR to produce an output signal which is determined by load on the line L adding a force to the computer means CR supplementing the forces derived from load movement.

In any event, when the load and motion conditions are such that the line L should be pulled from the drum 11 at a rapid rate, the system, as thus far described, will function to minimize the pressure applied to engage the slip clutches SC for the drum 11. At this time it is desired that the slip clutch SC of the reverse drum drive means RD be forced into engagement to assist in overcoming the drum inertia. To accomplish this function, a second proportional controller PC2 is employed to produce an output pressure for operating the slip clutch for the reverse drive means RD which increases as the output pressure from the proportional controller PC decreases.

This second controller PC2 is, in general, similar in structure and functional characteristics to the controller PC. However, the controller PC has the adjustable reset valve 322 which is not necessary in the controller PC2, and its function is to produce a reverse output signal as a function of the input signals from the relay CR and the traveling block position sensing means TS, as compared with the output from the controller PC.

More particularly, the controller PC2 may be a Moore Model 50X proportional. controller. or a Fisher proportional controller, as shown. In the schematic illustration of FIG. 7b, it will be seen that the outlet conduit 300 from the computer CR has a branch 300' connecting the outlet port 225 of the computing relay means CR to the control pressure inlet 304, and the conduit 85b leading to the controller PC from the position sensing means TS has a branch 85b leading to the inlet 301' of the controller PC2, whereby the pneumatic pressure at the outlet 302' supplied from a source (not shown) through an inlet 303', is determined by the inlet pressures at the inlets 301 and 304 and is proportional to the output from the computer CR and the load position sensing means TS, so that the slip clutch SC of the reverse drive RD is adapted to apply a controlled constant torque to the drum 1] which is a function of the output signal pressure of the computer or transmitter means CR and which increases as the output from the first controller PC decreases, and vice-versa.

The pressure signal from the chamber X of the computer CR is admitted to a bellows 309' of the controller PC2 which acts upwardly on the plate 308. Pressure supplied to the inlet 301 from the load position sensing means TS causes a change in pressure in a bellows 307' which is opposed to the bellows 309' and acts downwardly on the plate 308. The position of the plate 308 relative to a nozzle 310 to which controlled fluid pressure is supplied from the source inlet 303, is determined by the difference in pressures in the bellows 307 and 309'. If the output pressure from the load position sensing means TS increases, the pressure increases in bellows 307 causing the plate 308' to move from the nozzle 310, allowing greater flow through the nozzle to cause a reduction in the pressure in a chamber 311' of a control valve 312, causing a decreased downward 20 force on a diaphragm assembly comprising spaced diaphragms 313' and 314', which carries a valve seat 315', the passage through which communicates with the atmosphere through a port 316- between the diaphragms 313 and 314'. The valve seat 315' moves upwardly,

under the circumstances now being described, relative to an inlet and outlet valve having ahead 317 opening the exhaust passage through the valve seat 315 and a head 318 which is moved toward a seat 319' to reduce supply pressure into the valve outlet chamber 320' which acts on the diaphragm 314' until the valve seat 315' is again moved downwardly and causes downward movement of the inlet-outlet valve head 318' relative to its seat.

During the same time that pressure is decreasingin the chamber 320, such pressure is supplied to the out-.

put 302, and, thus, to the clutch SC for the reverse drive RD via a conduit 325 as well as to an adjustable proportioning valve 321 and, depending on the adjustment of the latter, a bellows 323. This bellows 323 acts downwardly on the plate 308 tending to move the latter away from the nozzle 310 to decrease pressure at the outlet 302 and in control valve chamber 320 and is opposed by the upward spring action of a bellows 324 which is vented to atmosphere.

If a change in the system causes a decrease in pressure at the inlet 304' to the controller PC2, then, the reverse action will occur in this controller, the ten-- dency being in either case to return to a zero pressure at the outlet 302, which decreasing pressure is a function of the outlet pressure from chamber X of the above-described computer means CR and the signal pressure from the load position sensing means TS which is in the reverse direction as compared with the output pressure from controller PC.

The outlet pressure from the controller means PC2 is supplied via the conduit 325' to cause actuation of the reverse drive clutch SC, but preferably a typical volume and ratio booster 325' is employed, whereby the pressure source (not shown) is connected to the inlet to the booster 326 from a relatively high pressure source,

and the pressure in conduit 325 acts on the usual pilot The output from the reverse controller PC2 is supplied to the reverse drive slip clutch SC through a mode selector valve means MS which will be hereinafter more fully described, and in addition, the controlled 1 reverse clutch operating pressure from the controller PC2 may be shutoff by a selector valve 329' and operating pressure supplied to the booster 326' via a conduit 330' under the control of a manual valve 3300.

It will now be understood, that when the selector valves 329 and 329 of the main drum clutch control system and the reverse clutch control systems are in the positions to allow automatic control, the clutches SC will be operated essentially in the following manner.

The traveling block or load position sensing means TS produces a reference signal representing relative motion of the load with respepct to the well head H;

while the vessel motion sensing means VS produces a reference signal representing motion of the vessel V relative to the well head H. These reference signals are compared in the computer means CR, and also the drum speed signal is added or substracted in the computer means CR, and an output signal is produced which adjusts the controller PC and the controller PC2, so that the pressure supply to the slip clutches SC for the drum 11 and the pressure supply for the slip clutch SC for the reverse drive RD are proportionally and inversely varied. When the drawworks machinery DW must be accelerated to compensate for downward vessel motion, the pressure supplied to the slip clutches SC for the drum 11 is increased to increase the torque transmitting capacity and overcome inertia; and, at the same time, operating pressure of the slip clutch SC for the reverse drive RD is reduced to minimize resistance to rotation of the drum 11 in the normal, load lifting direction. However, when the reverse vessel motion occurs and the vessel is accelerating upwardly, the clutch operating pressure supplied to the clutches SC for the drum 11 is reduced as required to allow the load to remain in the same position relative to the well head H, as line is pulled from the drum 1 1. At the same time, there is a proportional increase in the actuating pressure supplied to the slip clutch SC of the reverse drive RD, so that the drum 11 is positively reversely driven, overcoming the drum clutches SC and drum inertia, so that the line L will be played off the drum 11 at the necessary rate to compensate for upward vessel motion.

The foregoing control means is essentially position responsive, i.e., the slip clutches SC for the 'drum 11 and the slip clutch SC for the reverse drive RD. are adjusted or maintained constant depending upon relative movement between the load, the well head, and the vessel. Therefore, the system, as thus far described, is adapted to be utilized mainly during operations when the load is relatively light, say, when round tripping a string of drill pipe, shallow drilling, positioning tools in the well, lowering the well head, etc.

The invention also contemplates a load responsive system, in which the clutches SC are controlled in response to the load on the hoist mechanism and sensed at the crown block C by the load sensing means LS, in cluding the load cell 1 which may be the well known type adapted to produce a hydraulic pressure indicative of the applied load or compression of the cell.

Here again, the purpose is to reversely drive the drum 11, but in response to variations in the load applied to the load cell 1, which controls the torque transmitting capacity of the slip clutches SC.

Referring to FIG. 70, it will be seen that the output from the load cell 1 is conducted by a conduit 331 to a pneumatic controller or transmitter C3 to control the output pressure at an outlet 332 derived from a, source and applied at an inlet 333, so that the output pressure is adjusted to a valve determined by the load applied to the load cell 1.

Hydraulic pressure actuates a Bourdon tube 334 in the transmitter or controller C3 to move a plate 335 towards or away from a noule 336. A valve assembly 337 has an outlet chamber 338 communicating with the nozzle 336, and source pressure is supplied to the chamber 338 below a double diaphragm assembly including a diaphragm 339 and a diaphragm 340. An outlet chamber 341 communicates through a valve seat 342, which is carried by the diaphragms with an exhaust outlet 343 between the diaphragms 339 and 340, and a spring 344 normally biases the seat 342 .away from an inlet and outlet control valve 345 which is shiftable by the pressure in chamber. 338 acting on the diaphragm 339 and by the seat to a position allowing the flow of air from a valve inlet chamber 346 into the valve outlet chamber. On the other hand, if pressure in chamber 341 increases, the diaphragm 340 moves the seat 342 downwardly to allow pressure to discharge to atmosphere from the chamber 341 through the valve seat 342 and the exhaust port 343. Output pressure from chamber 341 of the valve 337 is supplied through a variable proportionin g valve 347 to an upper bellows 349 which acts downwardly on the beam 335, and below the beam 335 is a bellows 350 acting upwardly and supplied with a set point pressure at an inlet 351 through a variable pressure regulator 352. Such controllers or transmitters are well known, and the one illustrated is a Fisher Model 4151 transmitter, the purpose of which is to provide an output pressure signal at the outlet 332 which is determined by the magnitude of the load supported by the crown block C, and which signal is applied to a proportional reset controller PC4 and to a proportional controller PCS. The controller PC4 maintains an output pressure for operating or engaging the main drum clutches SC, while the controller PCS maintains an output pressure for operating the clutch SC of the reverse drive RD, whereby the respective drum clutches and reverse drive clutch are reversely operated to compensate for vessel motion in response to theload on the crown block C.

The proportional reset controller PC4 is the same as the aforementioned proportional reset controller PC, and, therefore, the same reference characters are applied and its mode of operation will be understood from the description above. Likewise, the proportional controller PCS is the same as the proportional controller PC2, and, therefore, the same reference characters are applied and its mode of operation will be understood from the description above.

In the present case, however, the input to the inlet 301 of the controller PC4 is from a manually operable set point regulator valve 400a, and the input to the inlet 304 is from the load responsive controller or transmitter PC3. Thus, the output from the controller PCS is determined by the relationship of the load responsive input signal and a set-point pressure which is variable by the driller to effect the desired load motion, up or down, and the variable set-point pressure may be observed on a LOAD REF. gauge. When the input signal from the load responsive controller PC3 increases, the output pressure from the controller PC4 will increase and be maintained constant, and vice-versa. The output from the outlet 3020f the controller PC4 is supplied to a volume and ratio booster 401a which determines the pressure applied to the main or drum clutches SC from the source inlet to the booster.

To control the reverse clutch SC for the reverse drive RD, the input signals to the proportional controller PCS are reversed, as compared with the controller PC4. More particularly the load signal from the transmitter PC3 is applied to the inlet 301' of the controller PCS and the set point pressure from the regulator 400a is applied to the inlet 304, so that the pressure at the outlet 302' of the controller PCS is also determined by the relationship between the load pressure signal from the transmitter PC3 and the setpoint pressure, but reversely proportional, as compared with the output from the controller PC4. Thus, the output from the reverse clutch controller PCS will decrease when the output from the controller PC4 increases, and vice-versa, so that when the main or drum clutches SC are released,

23 the reverse drive clutch SC will be more tightly engaged. To amplify the output signal from the controller PCS, it is connected to a pneumatic relay 402a and a volume and ratio booster 403a which controls the source pressure to the reverse, slip clutch.

The output from the boosters 401a and 403a are connected to the respective slip clutches SC, respectively, through the above-mentioned mode selector valve MS, which is operable to selectively connect the position sensing control system of FIGS. 7a and 7b, or the load sensing control system of FIG. 70 to the clutches SC. Moreover if desired, the mode selector ,valve could also incorporate another position for manual operation in lieu of the separate selector valves 329 and 329, previously described. It will also be understood, that if desired or necessary, the set point pressure applied to the controllers PC4 and PCS may be varied by utilizing a computer, such as the relay CR to compute load motion and drum rotation to establish a variable input signal to the controllers PC4 and PCS.

I claim: 7

1. In apparatus for supporting and moving well equipment from a floating vessel relative to the well, a drawworks including a fast line drum for taking up and playing out a load supporting line, first slipping drive means of variabletorque capacity for driving said drum in a direction to wind the line thereon, said first slipping drive means including an unidirectional source of power and adjustable torque capacity continuously slipping drum clutch means interposed between said source of power and said drum, the line being unwound from said drum when the tension in the line produces countertorque in said slipping drum clutch means that exceeds its momentary torque capacity, additional reverse drive means, including adjustable torque capacity continuously slipping reverse clutch means, for driving said drum in a direction to playout the line therefrom, and control means for increasing the torque capacity of said slipping reverse clutch means when the torque capacity of said first slipping drum clutch means is reduced, said first slipping drive means including a source of power and adjustable torque capacity slipping drive clutch means interposed between said source of power and said drum, and said additional reverse drive means including adjustable torque capacity slipping reverse clutch means, and control means for increasing the torque capacity of said reverse slipping clutch means when the torque capacity of said slipping drum clutch means is reduced, said control means including sensing means responsive to movement of said equipment relative to said vessel, sensing means responsive to movement of said vessel relative to the well, and means operable by said sensing means to oppositely adjust the torque capacity of said drum clutch means and said re verse clutch means.

2. In apparatus for supporting and movingwell equipment from a floating vessel relative to the well, a drawworks including a fast line drum for taking up and playing out aload supporting line, first slipping drive means its momentary torque capacity, additonal reverse drive means, including adjustable torque capacity continuously slipping reverse clutch means, for driving said drum in a direction to play out the line therefrom, and control means for-increasing the torque capacity of said slipping reverse clutchmeans whenthe torque capacity of said first slipping drum clutch means is reduced, said first slipping drive means including a source of power and adjustable torquecapacity slipping drum clutch means interposed between said source of power and said drum, and said additional reverse drive means in cluding adjustable torque capacity slipping reverse clutch means, and control means for increasing the torque capacity of said reverse slipping clutch means when the torque capacity of said slipping drum clutch means is reduced, said control means including load sensing means responsive to the load of said equipment, and means operable by said load sensing means to oppositely adjust the torque capacity of said drum clutch means and said reverse clutch means.

3. In apparatus for supporting and moving well equipment from a floating'vessel relative to the well, a drawworks including a fast line drum for taking up and playing out a load supporting line, first slipping drive means of variable. torque capacity for driving said drum in a direction to wind theline thereon, said first slipping drive means including a unidirectional source of power and adjustable torque capacity continuously slipping drum clutch means interposed between said, source of power and said drum, the line being unwound from said drum when'the tension in the line produces countertorque in said slipping drum clutch means that exceeds its momentary torque capacity, additional reverse drive means, including adjustable torque capacity continuously slipping reverse clutch means for driving said drum in a direction to play out the line therefrom, and control means for increasing the torque capacity of said slipping reverse clutch means when'the torque capacity of said first slipping drum clutch means is reduced, saiad first slipping drivemeans including a source of power and adjustable torque capacity slipping drum clutch means interposed between said source of power and said drum, and said additional reverse drive means including adjustable torque capacity slipping reverse clutch means, and control means for increasing the torque capacity of said reverse slipping clutch means when the torque capacity of said slipping drum clutch 7 means is reduced, said control means including load sensing means responsive to the load of said equipment, and means operable by said load sensing means to oppositely adjust the torque capacity of said drum clutch means and said reverse'clutch means, and means. for selectively rendering one of said sensing means operative and the other inoperative.

4. In apparatus for supporting and moving well equipment from a floating vessel relative to the well, a drawworks including a fast line drum for taking up and play.- ing out a load supporting line, first slipping drive means of variable torque capacity for driving said 'drum in a direction to wind the line thereon, said first slipping drive means including a unidirectional source of power and adjustable torque capacity continuously slipping drum clutch means interposed between said source of power and said drum, the line being unwound'from said drum when the tension in the line produces countertorque in said slipping drum clutch means that exceeds its momentary torque capacity, additional reverse drive means,-including adjustabletorque capacity continuously slipping reverseclutch means, for driving said

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2949038 *Jun 5, 1958Aug 16, 1960Howard B JopsonReversible transmission
US2950086 *Dec 9, 1957Aug 23, 1960Nat Supply CoDrilling control
US2977812 *Nov 10, 1958Apr 4, 1961Bendix CorpActuator with dither in neutral
US3350949 *Jul 28, 1965Nov 7, 1967 Electromechanical actuation apparatus
US3381939 *Jan 24, 1966May 7, 1968BrownHydraulic draw works with automatic power output control
US3469821 *Mar 20, 1967Sep 30, 1969Us NavyDepth control system for towed body
US3550735 *Sep 23, 1968Dec 29, 1970Hyster CoFluid pressure reversing clutches and brake for winch
US3596070 *Dec 8, 1969Jul 27, 1971Us NavyWinch control system for constant load depth
US3624783 *Jun 12, 1970Nov 30, 1971Santa Fe Int CorpMotion control system
US3675900 *Mar 16, 1970Jul 11, 1972Byron Jackson IncMotion compensating hoist
US3698690 *Dec 31, 1970Oct 17, 1972Koontz Machine & Welding IncHydraulically operated winch
US3738614 *May 13, 1971Jun 12, 1973E PetersonHoisting apparatus employing unitary clutch and brake assembly
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4147330 *Aug 16, 1977Apr 3, 1979A/S NormarMethod for setting down or taking up a load from or upon a loading location by means of a crane and an apparatus for carrying out the method
US4177973 *Mar 6, 1978Dec 11, 1979Ederer IncorporatedCable drum safety brake
US4200052 *Dec 14, 1977Apr 29, 1980The Secretary of State for Industry in Her Britannic Majesty's Government of the United Kingdon of Great Britain and Northern IrelandSystems for controlling the position of a moored floating vessel
US4324387 *Jan 30, 1980Apr 13, 1982Twin Disc, IncorporatedPower delivery system having a pressure modulated hydrodynamic retarder for controlling a load
US4502666 *Mar 22, 1983Mar 5, 1985Les Cables De LyonHaulage machine for hauling an elongate cylindrical unit
US4518153 *Jun 27, 1984May 21, 1985Ederer IncorporatedSafety mechanism for hoisting drums
US4875530 *Mar 24, 1989Oct 24, 1989Parker Technology, Inc.Automatic drilling system
US5123630 *Jun 11, 1990Jun 23, 1992William L. WatsonPortable winch
US6595494 *Apr 27, 2000Jul 22, 2003Huisman Special Lifting Equipment B.V.Hoisting device, with compensator built into hoisting cable system
US6868902Jan 13, 2003Mar 22, 2005Itrec B.V.Multipurpose reeled tubing assembly
US6871609Aug 28, 2003Mar 29, 2005Itrec B.V.Multipurpose tower for monohull
US6901998Mar 17, 2003Jun 7, 2005Itrec B.V.Method for using a multipurpose system
US6926103Mar 12, 2003Aug 9, 2005Itrec B.V.Splittable block on a derrick
US6926259 *Mar 12, 2003Aug 9, 2005Itrec B.V.Hoist system
US6926260May 5, 2003Aug 9, 2005Itrec B.V.Compensation and hoisting apparatus
US6932553Mar 17, 2003Aug 23, 2005Itrec, B.V.Multipurpose unit for drilling and well intervention
US6966106Jan 13, 2003Nov 22, 2005Itrec B.V.Method and apparatus for transporting and running tubulars
US6988459Oct 15, 2004Jan 24, 2006Itrec B.V.Multipurpose tower for monohull with moveable hatch
US7083004Oct 15, 2003Aug 1, 2006Itrec B.V.Cantilevered multi purpose tower and method for installing drilling equipment
US7178788 *Nov 5, 2004Feb 20, 2007Eagle Rock Manufacturing, LlcEven reeving system for a top drive earth drilling machine
US7264228 *Sep 9, 2005Sep 4, 2007J. R. Clancy, Inc.Counterweight assisted winch
US7275733 *Sep 19, 2006Oct 2, 2007J.R. Clancy, Inc.Compact drive for a counterweight assisted winch
US7556240 *Jul 7, 2009Mw Industries, Inc.Rig drawworks
US7559380Jul 14, 2009Eagle Rock Manufacturing, LlcTraveling swivel frame assembly with fixed brackets
US7584809May 10, 2007Sep 8, 2009Eagle Rock Manufacruting, LlcMobile transport rig with four axels
US7644784Jan 12, 2010Eagle Rock Manufacturing, LlcTransport watercraft
US7900893 *Nov 18, 2008Mar 8, 2011Schlumberger Technology CorporationElectronic control for winch tension
US8087461 *Jan 3, 2012Schlumberger Technology CorporationLogging while producing apparatus and method
US8280636 *Oct 2, 2012Key Energy Services Inc.Method and system for controlling a well service rig based on load data
US20040089215 *Aug 28, 2003May 13, 2004Joop RoodenburgMultipurpose tower for monohull
US20040151549 *Oct 15, 2003Aug 5, 2004Joop RoodenburgCantilevered multi purpose tower
US20050051072 *Oct 15, 2004Mar 10, 2005Joop RoodenburgMultipurpose tower for monohull with moveable hatch
US20070045600 *Sep 19, 2006Mar 1, 2007J.R. Clancy, Inc.Compact Drive for a Counterweight Assisted Winch
US20070063175 *Sep 9, 2005Mar 22, 2007J.R. Clancy, Inc.Counterweight Assisted Winch
US20090084543 *Sep 24, 2008Apr 2, 2009Peter FitzgeraldLogging while producing apparatus and method
US20090127525 *Nov 18, 2008May 21, 2009Lucas TeurlayElectronic Control for Winch Tension
US20110214856 *Sep 8, 2011Key Energy Services, Inc.Method and system for controlling a well service rig based on load data
US20140174725 *Dec 20, 2012Jun 26, 2014Schlumberger Technology CorporationDownhole Cable Sensor
Classifications
U.S. Classification254/270, 254/900, 254/340, 254/367, 254/337, 254/358, 254/274, 254/903, 175/27, 192/51
International ClassificationB66D1/50, E21B19/09
Cooperative ClassificationE21B19/09, B66D1/50, Y10S254/90, Y10S254/903
European ClassificationB66D1/50, E21B19/09
Legal Events
DateCodeEventDescription
Jan 17, 1989ASAssignment
Owner name: VARCO INTERNATIONAL, INC., A CA. CORP., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:HUGHES TOOL CONPANY-USA;REEL/FRAME:005013/0843
Effective date: 19880929
Aug 18, 1988ASAssignment
Owner name: HUGHES TOOL COMPANY-USA, 5425 POLK AVE., HOUSTON,
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BAKER HUGHES INCORPORATED;REEL/FRAME:004944/0763
Effective date: 19880718
Owner name: HUGHES TOOL COMPANY-USA, A DE CORP.,TEXAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BAKER HUGHES INCORPORATED;REEL/FRAME:4944/763
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BAKER HUGHES INCORPORATED;REEL/FRAME:004944/0763
Aug 8, 1988ASAssignment
Owner name: BAKER HUGHES INCORPORATED, TEXAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:HUGHES TOOL COMPANY;REEL/FRAME:005050/0861
Effective date: 19880609
Feb 22, 1983ASAssignment
Owner name: HUGHES TOOL COMPANY, P.O. BOX 2539, HOUSTON, TX. 7
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BJ-HUGHES INC.,;REEL/FRAME:004098/0273
Effective date: 19821231