US3799197A

US3799197A - Dual jack assembly for marine loading arms

Info

Publication number: US3799197A
Authority: US
Inventors: H Gibbons
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1972-04-03
Filing date: 1972-04-03
Publication date: 1974-03-26
Anticipated expiration: 1991-03-26

Abstract

A dual jack assembly for supporting the outboard end of a marine loading arm on the deck of a marine tanker to which it is connected during transfer of fluid between the tanker and a reservoir facility. The jack assembly comprises a pair of hydraulic motor-operated jacks secured to opposite ends of a saddle structure that serves the double function of attaching the assembly to the arm and transferring the arm''s moment load to the jacks. The jacks are oriented vertically, and each contains a helically threaded screw that is extended or retracted from a tubular housing in response to operation of the motor to which it is connected. The jacks are individually adjustable to compensate for different distances between the saddle structure and the tanker''s deck, and the lower end of each jack terminates in a ball joint that carries a foot-like base which adapts to the slope of the deck or other structure on which the jack is based.

Description

United States Patent [191 Gibbons [451 Mar. 26, 1974 DUAL JACK ASSEMBLY FOR MARINE LOADING ARMS Harold M. Gibbons, Long Beach, Calif.

[73] Assignee: FMC Corporation, San Jose, Calif.

[22] Filed: Apr. 3, 1972 [21] Appl. No.: 240,612

[75] Inventor:

[52] US. Cl 137/615, 248/49, 254/101, 254/102 [51] Int. Cl. F161 3/08 [58] Field of Search 248/49, 59, 157, 188.4; 254/98, 102, 101, 92; 137/615, 276; 415/66, 67

[56] References Cited UNITED STATES PATENTS 2,674,438 4/1954 Dalton 254/92 X 2,472,654 6/1949 Engelke 248/49 3,554,475 l/l97l Benno 248/59 X 2,739,788 3/1956 Weaver 254/102 3,472,474 10/1969 Fountain et 31.... 248/65 X 2,131,296 9/1938 Petsche et al 254/102 Primary ExaminerRoy D. Frazier Assistant Examiner-Rodney H. Bonck Attorney, Agent, or FirmW. W. Ritt, Jr.; C. E. Tripp 5 7] ABSTRACT A dual jack assembly for supporting the outboard end of a marine loading arm on the deck of a marine tanker to which it is connected during transfer of fluid between the tanker and a reservoir facility. The jack assembly comprises a pair of hydraulic motoroperated jacks secured to opposite ends of a saddle structure that serves the double function of attaching the assembly to the arm and transferring the arm's moment load to the jacks. The jacks are oriented vertically, and each contains a helically threaded screw that is extended or retracted from a tubular housing in response to operation of the motor to which it is connected. The jacks are individually adjustable to compensate for different distances between the saddle structure and the tankers deck, and the lower end of each jack terminates in a ball joint that carries a footlike base which adapts to the slope of the deck or other structure on which the jack is based.

10 Claims, 11 Drawing Figures PATENIEDMARZS 1914 3799197 sum 1 or s PATENTEOuanas I974 3799.197

sum 2 OF 5 I 66 6 v I I g I '18 22c 18 A *gpj, 543/; M I g;

PATENTEDIARZB I974 sum 3 or 5 TIB' q DUAL JACK ASSEMBLY FOR MARINE LOADING ARMS BACKGROUND OF THE INVENTION During transfer of petroleum or other fluid cargo between a reservoir facility and a marine tanker with a marine loading arm, such as that described in Bily US. Pat. No 3,382,893, issued May 14, 1968, various conditions arise which cause excessive moment loads to be imposed on the tankers manifold flange to which the arm is connected. The arms required to carry out this task with the giant modern supertankers are huge in size, having reaches up to 100 feet, diameters as great as 24 inches, and total weights of 30 or more tons. The moment loads imposed by the outboard end of these arms upon the tankers manifold can exceed the manifolds strength, such as when cast iron manifolds are involved, and this can result in failure of the manifold and potentially great spillage of the petroleum or other liquid being transferred. Although some manifolds are constructed of high strength steel, others of cast iron and other relatively low strength metals are still quite common, so that the problem of preventing manifold failure and cargo spillage is prevalent throughout the tanker industry.

Attempts to overcome this problem by counterbalancing the loading arm have enjoyed some success, but these couhterbalancing systems are huge in size and weight, and also are quite expensive. Furthermore, unless the loading arm can be counterbalanced while it is full of fluid, the weight of just the fluid can be sufficient to cause failure of the manifold. On the other hand, if the loading arm is counterbalanced when in a full condition, it is so out of balance when empty that it can constitute a real hazard to maneuvering it in and out of its stowed position.

Providing adjustable counterweights that can be hydraulically repositioned to change their counterbalancing moment while the arm is connected to the tanker manifold, thereby balancing the arm in both the empty and the full condition, is a solution to the problem. However, the equipment required to implement this solution is rather elaborate and expensive, and it can cause additional problems if for any reason it fails to function properly.

Accordingly, one object of the present invention is to provide an apparatus for supporting the outboard end of a marine loading arm on the deck or other sufficiently strong structure of a marine tanker while the arm is engaged with the tankers manifold flange.

Another object of the present invention is to provide a jack-type support for the outboard end of a marine loading arm that can be adjusted to compensate for unequal distances between the tankers manifold flange and the deck beneath it.

Still another object of the present invention is to provide a dual jack assembly for transferring the downward movement existing at the outboard end of a marine loading arm to the deck or other adequate support structure of a marine tanker instead of to the tankers manifold to which the arm is coupled.

Yet another object of the present invention is to provide a hydraulically powered, dual jack assembly for the outboard end of a marine loading arm, the assembly having a hydraulic system facilitating individual manipulation of the two jacks.

A further object of the present invention is to provide a dual jack assembly with feet or base members that automatically compensate for uneven deck or other surfaces on which the assembly is standing.

SUMMARY OF THE INVENTION The present invention comprises a dual jack assembly for mounting on the outboard end of a marine fluid loading arm, the assembly functioning to transfer the downward moment existing at that end of the arm to a tankers deck or other sufficiently strong foundation instead of to the tankers manifold to which the arm is coupled. The assembly comprises a pair of hydraulically powered screw jacks positioned vertically at opposite ends of a saddle structure that functions to support the arm and transfer its moment load to the jacks, and also to removably secure the assembly in rotatable manner about the arm s outer surface. Each jack is provided with its own hydraulic motor that rotates a helically threaded screw for extending and retracting the jacks leg with respect to the tubular housing in which the leg is slidably fitted. The bottom end of each leg carries a foot attached to it by a ball joint, enabling the foot to adjust to the slope of the tankers deck or other surface on which it rests. The two motors are interconnected by a hydraulic circuit that facilitates their operation separately and in unison, thereby assuring that both jack legs can be extended into full contact with the deck, etc., after the loading arm is coupled to the tankers manifold.

- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic representation in perspective of a double counterbalanced marine loading arm located on a wharf. with a dual jack assembly according to the present invention attached to the outboard end of the arm just behind its terminal flange.

FIG. 2 is a view like FIG. 1, illustrating the marine loading arm connected to a manifold flange of a marine petroleum tanker alongside the wharf.

FIG. 3 is a front elevation of the dual jack assembly of the present invention, on an enlarged scale, with the loading anns terminal flange removed and the jack assembly in retracted condition.

FIG. 4 is a longitudinal section of one of the jacks of the dual jack assembly of FIG. 3, on an enlarged scale.

FIG. 5 is an enlarged view taken along the line 55 of FIG. 4.

FIG. 6 is an enlarged view taken along the line 6-6 of FIG. 4.

FIG. 7 is an enlarged view taken along the line 7-7 of FIG. 4.

FIG. 8 is a fragmentary view of the upper portion of FIG. 4, showing the jack in partially extended condition.

FIG. 9 is a fragmentary view in perspective of the upper end of the jacks drive nut and the upper stop member on the jacks screw as they appear when the jack is in fully retracted condition.

FIG; 10 is a fragmentary view in perspective of the jacks drive nut and the lower stop member on the jacks screw as they appear when the jack is in fully extended condition.

FIG. 1 1 is a diagrammatic representation of one type of hydraulic system that can be employed for operating the dual jack assembly of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In reference first to FIGS. 1 and 2, the preferred embodiment of the present invention comprises a dual jack assembly designed for attachment to the outboard end of a marine loading arm 22 that is shown mounted on a wharf 24 for transferring fluid between a marine tanker 26 and a reservoir facility (not shown). The illustrated marine loading arm 22 comprises an inner fluid-conducting boom section 22a pivotally mounted on a riser 22r for movement with respect thereto about a horizontal axis A and a vertical axis B, an outer fluid-conducting boom section 22b pivotally connected to the inner boom section 220 for movement with respect thereto about another horizontal axis C, and a fluid-conducting coupling assembly 22c at the outer end of the outer boom section 22b for connecting the loading arm in fluid-tight manner. to the manifold flange 28 of the tanker 26.

The loading arm 22 is of the double counterbalanced type, including a primary counterweight 30 mounted on a rearward strut-like extension of the inner boom section 22a for counterbalancing the entire arm about the horizontal axis A at the riser 22r, and a counterweight 32 pivotally mounted about the risers horizontal axis A for counterbalancing the outer boom section 22b and its coupling assembly 22c about the horizontal axis C when the outer boom section is not in a vertical attitude. Such type of loading arm and its counterbalancing system are described at length in Bily U.S. Pat. No. 3,340,907, and since the details thereof are not critical to the present invention a further description of its structure is deemed not necessary for a clear and complete understanding of the present invention.

Referring now to FIGS. 3 and 4, the dual jack assembly 20 comprises a pair of

individual jacks

34,36 fixed in vertical orientation to opposite ends of a support structure 38. This support 38 includes a transverse lbeam element 40, and an arcuate saddle element 42 secured to the l-beam by upright struts 43. The support 38 functions not only to transfer the downward move ment load of the loading arm to the

jacks

34,36, and through them to the tankers deck on which they stand, but also to cooperate with an arcuate strap member 44 to removably attach the entire jack assembly 20 to the coupling assembly 226.

Solely for illustrative purposes, the dual jack assembly 20 is shown positioned on the coupling 22c just behind its terminal flange 46 (FIGS. 1 and 2), with the saddle 42 and the strap 44 fitting in a groove 50 (FIG. 3) in the couplings outer surface. It should be understood, however, that if desired the jack assembly 20 also can be attached to the couplings swivel joint 56 (FIG. 3) that is located behind the couplings terminal flange 46.

A pair of bolts 52 (FIG. 3) provide a means for securing the strap 44 to cars 54 fixed to the outer surfaces of the

jacks

34,36, so that the jack assembly 20 can be quickly and easily removed from the loading arm should repair or replacement become necessary. Preferably the strap 44 is secured just tight enough to be snug, but loose enough to allow the jack assembly 20 to rotate relative to the coupling 22c, should that for any reason be necessary. It should be noted that the vertical support provided by the dual jack assembly 20 is centrally positioned beneath the coupling 220, so that no lateral or twisting moment is imparted to the arm as would occur if but a single jack were mounted on one side of the coupling.

As seen best in FIG. 4, each jack includes an outer tubular housing 60, a tubular leg 62 slidably received in the housing 60, a helically-threaded screw 64 extending downwardly inside the leg 62, a hydraulic powered motor 66 (67 for jack 36), and a foot 68 connected to the leg 62 by a ball joint 70. The housing 60 is welded or otherwise fixed to the transverse l-beam 40, and the ears 54 to which the strap 44 is bolted are welded or otherwise fixed to the housing at a suitable height above the I-beam.

Each of the

hydraulic motors

66,67 is secured to a bearing housing 72 by means of cap screws 74, and the bearing housing 72 is in turn secured by cap screws 76 to an annular flange 78 welded or otherwise fixed to the upper end of the jacks housing 60. Each hydraulic motor also has a shaft 80 (FIG. 4) that is non-rotatably connected, i.e., splined, keyed, etc., to a screw shaft 82 that is welded or otherwise fixed to the upper end of the helically-threaded screw 64. A radial bearing 84 and a thrust bearing 86 are provided between the shaft 82 and the bearing housing 72. Accordingly, when the hydraulic motors are operated, each shaft 80 causes the shaft 82 to which it is connected to rotate, thereby also rotating the related screw 64. However, during this rotation the housing 60 remains stationary.

The leg 62 is provided with a longitudinal groove 62a (FIG. 4) along its outer surface that accepts an antirotation guide member 90 that extends inwardly from, and is bolted or otherwise secured to, the lower end of the housing 60. Thus the housing 60, which remains stationary with respect to the coupling assembly 22c, prevents the leg 62 from rotating when the hydraulic motor is operating.

A drive nut 92 is welded or otherwise flxed to the upper end of the leg 62, and is provided with inner helical threads that mesh with the outer helical threads on the screw 64. Since the leg 62 is incapable of rotation, the drive nut 92 likewise cannot rotate. Therefore, as the screw 64 rotates the drive nut 92 is caused to move along the screw 64, carrying with it the leg 62.

Since the threads on the screw 64 and the drive nut 92 are left handed, when the screw is rotated clockwise as viewed from above, i.e., in the direction of the arrow in FIG. 9, it causes the drive nut to move downwardly, thereby extending the leg 62 and the foot 68 from the housing 60. In corresponding manner, when the motor is reversed to rotate the screw 64 counterclockwise, i.e., in the direction of the arrow in FIG. 10, the drive nut is caused to move upwardly in the housing 60, thereby retracting the leg 62 and the foot 68.

A stop (FIGS. 5 and 9), bolted or otherwise secured to the shaft 82, cooperates with an axially extending stop element 102 on the top of the drive nut 92 to prevent further upward movement of the nut with respect to the screw 64 when the jacks leg 62 is fully retracted. Similarly, the lower end of the screw 64 (FIGS. 6 and 10) is provided with a radially extending stop element 104 that cooperates with a stop 106 on the lower end of the drive nut 92 to prevent further downward movement of the nut with respect to the screw when the jacks leg 62 is in its fully extended position. Accordingly, it is seen that maximum movement of the drive nut 92 along the screw 64 is restricted to the limits established by the stops 100,106 and the cooperating stop elements 102,104, thereby preventing over-extension or retraction of the leg 62 with respect to the housing 60. It should, however, be understood that downward movement of the nut 92, and therefore also the leg 62, will cease when the foot 68 comes to rest on the tankers deck or other supporting surface, even though the nut has not reached the lower end of the screw 64. This result is achieved by the use of highslip type motors at 66,67, and the particular manner by which they are interconnected, as described below. Hence the dual jack assembly 20 adapts itself to any spacing between the tankers manifold and the deck, within of course the limits of extension of its legs.

The

hydraulic motors

66,67 for the

jacks

34,36 preferably are connected in series in a hydraulic circuit diagrammatically illustrated in FIG. 11, thus assuring that the travel of each leg 62 will be equal. This hydraulic circuit comprises a conventional three-way valve 110 for starting and stopping the motors and controlling the direction of flow of hydraulic fluid under pressure through them, and a pair of needle valves or other variable orifice devices 112,114, each of which is connected in parallel with the inlet and outlet ports of its respective motor, to regulate the quantity of flow through the motors for balancing their operation.

The

motors

66,67 are of the high-slip type, so that if the tankers deck, etc., is uneven the motor of the first leg to contact the deck will stall and pass enough fluid to facilitate continued operation of the other motor until the second leg also comes to rest against the deck. Furthermore, during retraction of legs that have become out of phase, for example as above where one leg reaches the deck before the other, the motor which first stalls when its leg reaches its upper limit of travel, i.e., when its stop 100 and stop element 102 come into contact, will allow sufficient passage of fluid to the other motor so that the other leg also can be fully retracted. This feature is especially important where the deck or other supporting surface beneath one of the jacks is not spaced from the tankers manifold the same as that beneath the other jack.

The

motors

66,67 are operated with hydraulic pressure preferably sufficient to assure that the jacks provide a small upward force on the loading arms coupling assembly 220 before the motor stall. When the valve 110 is closed, the jacks will then remain in position to support the weight of the coupling and the loading arm, and transfer this weight in a balanced manner to the deck or other structure with which the feet 68 are in contact.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

I claim:

I. A marine loading arm including a fluid-conducting boom section adapted for coupling to a manifold flange of a marine tanker, and a jack assembly mounted on the boom section for supporting the loading arm on the tanker, said jack assembly comprising:

a. a pair of screw jacks, each jack having a housing,

a leg extensible from and retractile into said housing, and a helical screw for extending and retracting said leg with respect to said housing;

b. power means for rotating the helical screws;

c. first means for securing the jacks to each other in spaced, generally parallel relationship; and

d. second securing means cooperating with the first securing means to mount the jack assembly on the loading arm.

2. A marine loading arm according to claim 1 wherein the power means comprises a pair of hydraulic motors, one secured to the housing of each jack, and means interconnecting each motor with the helical screw of its respective jack.

3. A marine loading arm according to claim 2 wherein the interconnecting means of each jack comprises a motor shaft rotatable with respect to the jack housing, and a screw shaft non-rotatably secured to the motor shaft and the helical screw.

4. A marine loading arm according to claim 1 wherein the first securing means comprises a rigid beam member fixed at each end to the jack housings, and a saddle member fixed to the beam member in an upwardly oriented manner when the assembly is positioned in its functional orientation.

5. A marine loading arm according to claim 4 wherein the second securing means comprises an elongated strap removably securable at each end to the jack housings, the strap cooperating with the saddle member to removably secure the assembly to the loading arm.

6. A marine loading arm according to claim 1 wherein each extensible leg has an inner and an outer end, a drive nut threaded about the screw-shaft and fixed to the inner end of the leg, and a foot member pivotally connected to the legs outer end.

7. A marine loading arm according to claim 6 including anti-rotation guide means extending between each jack housing and its extensible leg, whereby when the screw is rotated with respect to its housing the extensible leg is prevented from rotating.

8. A marine loading arm according to claim 7 including stop means on the screw shaft cooperating with stop means on the drive nut to preclude over-extension and over-retraction of the leg with respect to the housing.

9. A dual jack assembly adapted for supporting the outboard end of a marine loading arm, comprising:

a. a pair of screw jacks, each jack having a housing,

b. power means for rotating the helical screws, said power means comprising a pair of hydraulic motors, one secured to the housing of each jack, and means interconnecting each motor with the helical screw of its respective jack, said motors being connected in series into a source of pressurized hydraulic fluid, said power means further comprising a variable orifice flow control means connected across the fluid inlet and outlet of each motor;

10. A dual jack assembly according to claim 9 wherein the motors are of the high-slip type facilitating continued but slow rotation of one motor after rotation of the other motor has terminated.

UNITED STATES PATENT OFFICE QER'HFEATE OF CORRECTIQN PATmr NO. 3,799,197

DATED March 26,1974

iNVENTORt'S) HAROLD M. GIBBONS it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: 6

Column 3 lines 42-43 change "move-ment" to moment Signed and gals this 9 fifth of August 1975 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN AINSII'MR ffifl ('nmmixsr'unvr uj'lulcnrs and Trulz'murkx

Claims

1. A marine loading arm including a fluid-conducting boom section adapted for coupling to a manifold flange of a marine tanker, and a jack assembly mounted on the boom section for supporting the loading arm on the tanker, said jack assembly comprising: a. a pair of screw jacks, each jack having a housing, a leg extensible from and retractile into said housing, and a helical screw for extending and retracting said leg with respect to said housing; b. power means for rotating the helical screws; c. first means for securing the jacks to each other in spaced, generally parallel relationship; and d. second securing means cooperating with the first securing means to mount the jack assembly on the loading arm.

6. A marine loading arm according to claim 1 wherein each extensible leg has an inner and an outer end, a drive nut threaded about the screw shaft and fixed to the inner end of the leg, and a foot member pivotally connected To the leg''s outer end.

9. A dual jack assembly adapted for supporting the outboard end of a marine loading arm, comprising: a. a pair of screw jacks, each jack having a housing, a leg extensible from and retractile into said housing, and a helical screw for extending and retracting said leg with respect to said housing; b. power means for rotating the helical screws, said power means comprising a pair of hydraulic motors, one secured to the housing of each jack, and means interconnecting each motor with the helical screw of its respective jack, said motors being connected in series into a source of pressurized hydraulic fluid, said power means further comprising a variable orifice flow control means connected across the fluid inlet and outlet of each motor; c. first means for securing the jacks to each other in spaced, generally parallel relationship; and d. second securing means cooperating with the first securing means to mount the jack assembly on the loading arm.