US3401917A

US3401917A - Hydraulic cylinder apparatus

Info

Publication number: US3401917A
Application number: US562400A
Authority: US
Inventors: Jr Robert E Bradbury
Original assignee: Offshore Co
Current assignee: SONAT OFFSHORE DRILLING Inc
Priority date: 1966-07-01
Filing date: 1966-07-01
Publication date: 1968-09-17
Anticipated expiration: 1985-09-17

Description

Sept. 17, 1968 Filed July 1, 1966 R. E. BRADBURY, JR

HYDRAULI C CYLINDER APPARATUS 5 Sheets-Sheet l I INVENTOR poggprf 5990609; UR.

A rmp/vc'vs R. E. BRADBURY, JR 3,401,917

HYDRAULIC CYLINDER APPARATUS Sept. 17, 1968 5 Sheets-Sheet 2 p fizg yroe J? oseer .Bmwumy IL i 1. 2 6y Anni/vars Filed July 1, 1966 P 1968 R. E. BRADBURY, JR 3,401,917

HYDRAULIC CYLINDER APPARATUS 5 Sheets-Sheet 5 Filed July 1, 1966 INVENTOR. Y a-w- 59906049 d2 By W W/ Anne/1m P 1968 R. E. BRADBURY, JR 3,401,917

HYDRAULIC CYLINDER APPARATUS Filed July 1, 1966 5 Sheets-Sheet4 Ti qAA.

] N VENTOR.

WEWE fiewaugyak A voe/veys Sept. 17, 1968 R E. BRADBURY, JR 3,401,917

HYDRAULIC CYLINDER APPARATUS 5 Shets-Sheet 5 Filed July 1, 1966 INXIENTOR. V W 99 4); 4

BY fi%/ Am /vars Ln J k fi Q 1.. 1 O 6 a. 5 m 8 g @m 5 United States Patent 3,401,917 HYDRAULIC CYLINDER APPARATUS Robert E. Bradbury, Jr., Houston, Tex., assignor to The Oifshore Company, Houston, Tex., a corporation of Delaware Filed July 1, 1966, Ser. No. 562,400 17 Claims. (Cl. 254-106) ABSTRACT OF THE DISCLOSURE The hydraulic cylinder apparatus includes a pin cylinder assembly secured within the pin engaging the support leg of the marine platform and fixed to the pin housing. The pin cylinder assembly operates to reciprocate the pin relative to the pin housing within a limited amount of space. Also, the components of the apparatus are of such weight as to be handled manually.

This invention relates to a hydraulic cylinder apparatus. More particularly, this invention relates to a hydraulic cylinder apparatus for a jacking assembly. Still more particularly, this invention relates to a hydraulic cylinder apparatus for a jacking assembly of a marine platform.

Marine platforms, such as a dock or an offshore oil well drilling barge, which are buoyant and are adapted to be towed or otherwise propelled to a marine site are frequently provided with a plurality of openings through which a corresponding number of supporting legs are arranged to be extended. The supporting legs are sometimes lowered into abutment with the marine bottom by a series of jack assemblies secured to the platform, which cooperate through reciprocally mounted support pins with apertured channels on the faces of the legs to lower the legs in a series of strokes. Subsequently and in like manner, the platform is sometimes raised on the legs above the water surface. Conversely, such jack assemblies are sometimes used to lower the platform on the legs to or below the water surface, as well as to raise the legs from the marine bottom in order to permit transportation of the platform to another site.

Heretofore, jack assemblies of the afore-described type for raising and lowering the legs of a marine platform as well as the platform have utilized hydraulic cylinder and piston devices to move the load-supporting pins into and out of the apertured channels on the legs. However, the hydraulic cylinder and piston devices have been fixed to the pins in a tandem relation, i.e., one behind the other. As a result, these hydraulic devices have occupied a relatively large space within the jacking assemblies and have also had a relatively large bulk and weight. Consequently, these hydraulic devices have been unwieldy and inconvenient for manual handling during installation and servicing. In addition, the load-supporting pins and pistons of these hydraulic devices have required an additional means for securing one to the other for proper cooperation in use. This has not only added to the cost of the hydraulic devices but has also allowed a transmission of forces through the securing means in the form of bending stresses, causing premature failure of seals for example. Use of an additional securing means has also increased the difiiculty of obtaining and maintaining proper alignment of the various cooperating members of hydraulic devices.

Generally, the invention provides a hydraulic cylinder apparatus containing a pin-actuating means within a load supporting pin, which apparatus may be used in jacking assembly for raising and lowering the legs and barge of a marine platform. The pin-actuating means includes a pin cylinder assembly which is fixedly secured within the load-supporting pin, the pin being in turn reciprocally 3,401,917 Patented Sept. 17, 1968 mounted in the pin housing of the jacking assembly. It also includes a piston rod which is mounted Within the pin cylinder and fixedly secured to the pin housing, and hydraulic means for reciprocally moving the pin cylinder and load-supporting pin on the piston rod. The loadsupporting pin may be reciprocated by the hydraulic means into or from an apertured channel on a support leg of the marine platform so that the support leg can be moved relative to the barge generally in accordance with the jacking operation described in US. Patents Nos. 2,920,870 and 2,932,486 which issued on Jan. 12, 1960, and Apr. 12, 1960, respectively.

It is one object of this invention to provide a hydraulic cylinder apparatus which mounts a pin-actuating means within a load-supporting pin.

It is another object of the invention to provide a hydraulic cylinder apparatus having a pin-actuating means and a load-supporting pin which are of such weight and bulk that they can be manually handled for servicing or assembly.

It is another object of the invention to provide a hydraulic cylinder apparatus which requires a minimum amount of space for operation.

It is another object of the invention to provide a jacking assembly with a pair of opposed hydraulic cylinder apparatuses at two vertical planes to carry the weight of a barge of a marine platform as well as to support the legs of the platform.

It is another object of the invention to provide a hydraulic cylinder apparatus which is relatively inexpensive to manufacture and use.

It is another object of the invention to provide a hydraulic cylinder apparatus which is relatively easily repaired and serviced.

These and other objects and advantages of the invention will become more apparent from the following de tailed description of an embodiment of the invention taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a plan view of a preferred embodiment of a jacking assembly incorporating a pair of hydraulic cylinder apparatuses disposed about a marine platform support leg according to the invention;

FIG. 2 illustrates a partially broken-away vertical view of the hydraulic cylinder apparatuses of the jacking assembly of FIG. 1;

FIG. 3 illustrates an end view of a lower hydraulic cylinder apparatus of FIG. 2;

FIG. 4 illustrates a fragmentary cross-sectional view taken on line 4--4 of FIG. 3 of the hydraulic cylinder apparatus of FIG. 3 in extended position;

FIG. 4A illustrates a view similar to FIG. 4 of the hydraulic cylinder apparatus in retracted position;

FIG. 5 illustrates a fragmentary cross-sectional view of the pin cylinder and piston rod of a preferred embodiment of the hydraulic cylinder apparatus of the invention;

FIG. 5A illustrates a cross-sectional view taken on line 5A5A of FIG. 5;

FIG. 53 illustrates a view of a retaining ring on an end of the pin cylinder;

FIG. 6 illustrates a plan view of the pin housing for the hydraulic cylinder apparatus;

FIG. 7 illustrates a side view of the pin housing of FIG. 6; and

FIG. 8 illustrates a cross-sectional view of the pin housing taken on line -88 of FIG. 7. I

Referring to FIGS. 1 and 2, each support leg or caisson 10 passing through the barge 11 of a marine platform has a pair of elongated channel-shaped racks 12. secured along diametrically opposed portions of the outer surface of the leg or caisson. The web of each rack 12 has a series of vertically spaced apertures 13 which cooperate with a jacking assembly 14, in a manner as described in the two aforesaid US. patents, for mounting the leg relative to the barge 11.

The jacking assembly 14 includes a pair of vertically spaced yokes 15 each of which envelopes the leg 10 as shown in FIG. 1, and each of which carries a pair of diametrically disposed hydraulic cylinder apparatuses 18 in confronting relationship to the apertured racks 12 on the leg 10. Each yoke 15 comprises a pair of semi-circular members 16, 16' which have respective centers 17, 17' offset from each other (FIG. 1). Oflsetting the

centers

17, 17 of the

semi-circular members

16, 16 of yokes 15, decreases the overall dimensions of yoke 15 and thereby results in a saving in both space and cost of materials. Oifsetting the centers also provides a larger area of contact between

members

16 and 16 and hydraulic cylinder apparatuses 18, thereby providing a more satisfactory distribution of stresses between the

yoke members

16, 16 and apparatuses 18, and thereby also providing increased surfaces for the securing, as by welding, of

members

16, 16 to apparatuses 18. Each yoke member 16, 16' is square in cross-section and comprises a plurality of plates secured to one another as by welding. Members 16, 16' further comprise a plurality of spaced, internal stitfeners 90, and member 16 includes a plurality of spaced brackets 91 for holding hydraulic piping 92 in place within yoke 15. The hydraulic piping 92. extends from the hydraulic cylinder apparatuses 18 through member 16 to T-connectors 93, and then to a means 94 for controlling the flow of hydraulic fluid into piping 92 and the return of fluid therefrom.

Yokes 15 are operatively connected to each other by a pair of telescoping hydraulic side jacks 19, each of which is secured between and to a pair of vertically aligned hydraulic cylinder apparatuses 18. Side jacks 19 and hydraulic cylinder apparatuses 18 are preferably actuated and controlled through a control system as disclosed in copending application of Robert E. Bradbury, Jr. for Jacking Apparatus and Controls, filed on even date herewith. Upon actuation, side jacks 19 move the yokes 15 and consequently the hydraulic cylinder apparatuses 18, in a stepwise fashion vertically along the racks 12 on the leg 10 to raise or lower the leg 10 through the barge 11, or to raise or lower the barge 11 on the leg 10.

Barge 11 is provided with a pair of shock absorbers 20 on its deck 21 for abutting the lower hydraulic cylinder apparatuses 18 when they are in the position shown in dashed-lines in FIG. 2, as well as a pair of shock absorbers 22 mounted at a point 23 which is fixed in position relative to deck 21 for abutting the upper hydraulic cylinder apparatuses 18. Relative movements of barge 11 with respect to leg 10 are obtained generally as described in the aforesaid two US. patents.

Referring to FIGS. 3 and 4, each hydraulic cylinder apparatus 18 includes a pin housing 24 secured, as by bolts 25, to a side jack 19 and, as by welding, to members 16, 16' of yoke 15. Each hydraulic cylinder apparatus 18 further includes a load-supporting or load-engaging pin 26 slidably mounted concentrically within the pin housing 24, a pin cylinder assembly 27 fixedly mounted concentrically within a load-supporting pin 26, and a piston rod 28 fixedly mounted by a bracket 29 to the pin housing 24. To provide preferable conditions of bearing stress distribution between the racks 12 and the loadsupporting pins, each hydraulic cylinder apparatus 18 is secured to a side jack 19 at a slight downward angle to a horizontal plane passing through the leg 10.

A pair of fixed angle guide brackets 30 are aflixed to one end of each pin housing 24 and disposed about an apertured channel-shaped rack 12 on leg 10 for guiding the hydraulic cylinder apparatus 18 along the apertured member 12 during operation of the jacking assembly 14. In addition, each pin housing 24 is formed with a central bore 31 having a pair of spaced annular bearing lands 32 for slidably guiding pin 26 concentrically therein. Further, an arcuate shaped rotation keeper 33 is secured, as by welding, in the forward end of the bore 31 near the guide bracket end of pin housing 24, to prevent outward movement of pin 26 and to maintain proper alignment between pin 26 and a limit switch assembly 78 more fully described below. Keeper 33 also serves to limit rotational movement of pin 26 and to limit sideways movement of pin 26 to the extent of the clearance 95 between pin 26 and keeper 33.

The load-supporting pin 26 is formed with an enlarged body portion 34 slidably disposed in the bearing lands 32 having a central counterbore 35 at one end and a reduced stub shaft portion 36 of preferably square or rectangular cross-sectional shape at the other end. Pin 26 is preferably of tempered steel. The stub shaft portion 36 of pin 26 is centrally located on the pin to project into an aperture 13 of channel-shaped rack 12 on leg 10 when pin 26 is extended. The apertures 13 of rack 12 are of greater dimensions than the stub shaft portion 36 of pin 26 and provide clearances for the stub shaft portion 36 during movement of pin 26. However, when in loadsupporting position, the stub shaft portion 36 will be in contact with the upper or lower side wall of the aperture 13.

Referring to FIGS. 3, 4, 5, 5A and 5B, pin cylinder assemby 27 is fixedly mounted, as by bolts 37, to one end of pin 26 for concentric disposition within bore 35 (FIG. 4). The pin cylinder assembly 27 includes a cylindrical barrel 38 (FIG. 5) which is closed at one end by a cap 39 secured thereto as by welding and which is provided at the other end with internal threading 40 to threadably engage an externally threaded mounting collar 41. An O-ring seal 42 is interposed between barrel 38 and mounting collar 41 to seal the mating surfaces against a flow of fluid. In addition, a pair of lock screws 43 are mounted in barrel 38 to thread into mounting collar 41 to prevent loosening of the collar 41 from the barrel 38.

The mounting collar 41 includes a radial flange portion 44 which is provided with a series of holes 45 for the passage of the bolts 37, and an internal annular bearing surface 46 for the piston 28 concentric to the external threads 47. Bearing surface 46 is formed, for example, of a A inch brass "bearing sleeve. The flange 44 has an annular retaining ring 48 secured to the exterior face of the flange as by circumferentially spaced bolts 49 for retaining a seal packing 50 between the flange portion 44 of collar 41 and the piston rod 28 to prevent a flow of dirt, fluid or corrosive material between the pin cylinder assembly 27 and piston rod 28. Retaining ring 48 is provided with a bearing surface 51 such as a 34 inch brass bearing sleeve for slidably mounting the pin 28 therein, and a wiper-scraper member 97.

A shock absorber assembly 52 is positioned about the flange portion 44 of mounting collar 41 to absorb shock loading between the pin cylinder assembly 27 and pin 26, and to provide a controlled amount of freedom for piston rod 28 in the event of a slight misalignment of piston rod 28 with respect to pin. cylinder assembly 27. The shock absorber assembly 52 includes a annular pad 53 of resilient material on each side of flange 44, and an annular metal retaining ring 54. Ring 54 and pads 53 are apertured in conformity (FIG. 5B) with flange 44 to permit passage of bolts 37 therethrough for securing the shock absorber assembly 52 in position.

Piston rod 28 (FIGS. 5 and 5A) is slidably mounted within the bearing surfaces 46, 51 of the cylinder pin assembly 27 in spaced relation to the barrel 38. The piston rod 28 has an annular land 55 near its forward end, which is spaced from the mounting collar 41. The land 55 has a bearing surface 56 formed for example of a inch brass sleeve, which slidably engages the interior wall of the barrel 38 so as to define a chamber 57 between the cylinder pin assembly 27 and the piston rod 28. In addition,

a cup-shaped member 58 is secured, as by bolts 59, to the end of the piston rod 28 to form a chamber 60 with the cap 39 which is coaxial with the piston rod 28. Cupshaped member 58 is provided with a circumferential bearing surface 61, for example a inch brass sleeve, which slides on the interior wall of the barrel 68. Cup shaped member 58 and land on the piston rod 28 retain a seal 62 between the barrel 38 and piston rod 28 to prevent flow of fiuid between chambers 57 and 60. Seal 62 may be a chevron packing, piston rings or an equivalent sealing means.

Piston rod 28 is further formed with a pair of internal passages 63, 64. One of the passages 63 communicates between chamber 57 and a port 100 at the external end of the piston rod 28, and the other passage 64 communicates between chamber and port 101 at the end of the piston rod.

Referring to FIGS. 3, 4 and 5, the external end of the piston rod 28 is formed with a shoulder portion 65, and

a reduced cylindrical portion 66 to fit within an aperture H 67 of mounting bracket 29. The reduced portion 66 is provided with a slotted keyway '68 which receives a suitable key (not shown) on mounting bracket 29 for aligning piston rod 28 in pin cylinder assembly 27. The reduced portion 66 is also threaded at the end to receive a threaded nut 69 which abuts bracket 29 to fixedly secure piston rod 28 in place.

The mounting bracket 29 is generally U-shaped with a pair of flanged legs 70 which are secured, as by bolts 71, to the pin housing 24 to maintain piston rod 28 and pin housing 24 in a fixed relation.

A pair of suitable

hydraulic fittings

72, 73 are fitted as by threading within the

ports

100, 101 at the end of the piston rod 28 and to the hydraulic piping 92 to provide for the escape from and entry of hydraulic fluid into the chambers 57, 60 from hydraulic control means 94. A

hydraulic control system as described in the aforementioned copending patent application is preferably used with the apparatus of this invention.

Referring to FIGS. 6, 7 and 8, pin housing 24 is preferably formed of one piece of metal with a plurality of circumferentially spaced threaded holes 74 in its top surface to receive the bolts 25 securing the hydraulic cylinder apparatus 18 to the side jacks 19, and With two sets of linearly aligned threaded holes 75 in a side surface to receive the bolts 71 securing the mounting bracket 29. In addition, the pin housing 24 is provided with a fluid port means 76 for introducing lubricating means such as grease between the pin housing 24 and pin 26. Further, the side surface is provided with a set of threaded holes 77 for receiving a limit switch assembly 78, which provides a means for indicating when pin 26 of the hydraulic cylinder apparatus 18 is fully expanded, fully retracted or in an intermediate position.

Referring to FIGS. 3 and 4, limit switch assembly 78 includes a limit switch 79, for example, a National Acme Limit Switch SL4-N-W with D-1260 lever, which is mounted on a bracket 80 secured, as by bolts 81, to the pin housing 24 to cooperate with a lug 82 mounted, as by a bolt 83, to a bracket 84 having a base 85 secured to the pin 26, as by bolts 86. Lever 87, which has a roller at its end, is positioned in the path of the leg 84 as well as the base 85 to be moved into a series of angular positions relative to the limit switch 79 which correspond to particular positions of expansion and retraction of the pin 26 relative to the leg 10.

It will be noted that welding is generally not required to secure the members of the pin cylinder assembly 27 to one another, or to secure the pin cylinder assembly 27 to pin 26. It is one feature of this embodiment of this invention that it is possible to minimize the use of welding, if so desired, and thereby avoid undesirable side effects of welding such as thermal distortion of components, which sometimes results in prior hydraulic cylinder assemblies.

Considering now examples of operation of this embodiment of the invention, in order to lower barge 11 on leg 10 when the leg is supported on the marine bottom with the pins 26 of the lower pair of hydraulic cylinder apparatuses 18 positioned in respective apertures 13 of the racks 12 on leg 10 and the upper pair of hydraulic cylinder apparatuses 18 abutting the shock absorbers 22 at the fixed point 23, the upper pins 26 are first inserted into respective apertures 13 in the rack 12. Thereafter, with the load of the barge 11 supported on the upper pins, the lower pins are retracted from the racks. Thereafter, the telescoping jacks 19 are expanded from an initial closed position to a fully opened position to increase the spacing between the yokes 15, for example, from an initial spacing of about 12 feet to a spacing of about 18 feet. When the retracted lower pins 26 are aligned with a lower set of apertures 13 in the racks 12 (FIG. 2), the pins 26 are inserted into the racks and positioned in loadsupporting relation against the lower side wall of the apertures 13'. Next, the upper pins 26 are retracted and the jacks 19 telescoped together to lower the barge 11 on the leg 16. Subsequent lowering of the barge 11 is carried out by repeating these steps.

Referring to FIGS. 4, 4A and 5, each hydraulic cylinder apparatus 1 8 is operated in the following manner. With the pin 26 retracted out of a rack 12 (FIGS, 4A and 5) a quantity of pressurized hydraulic fluid is introduced into chamber 60 through port 101 and hydraulic piping 92. After chamber 60 is filled with fluid, further introduction of fluid causes the pin cylinder assembly 27 to move along the piston rod 28 while any fluid in chamher 57 is expelled through port as chamber 57 is reduced in size. Since the pin cylinder assembly 27 is fixed to the pin 26, pin 26 also moves relative to the piston rod 28 so that the stub shaft portion 26 of pin 26 enters an aperture 13- of the rack 12. Fluid is continuously introduced under pressure until the stub portion 36 of pin 26 is fully inserted in the rack 12 as indicated by contact of the pin 26 with the keeper 33 as well as by a control signal corresponding to a set position of the lever 87 of the limit switch 79.

In order to retract the pin, 26, hydraulic fluid is introduced under pressure into the reduced chamber 57 through port 100 and hydraulic piping 92 to move the pin cylinder assembly 27 on piston rod 28 so as to reduce chamber 60 while expelling fluid from chamber 60 through port 101. As a result, the pin 26 is retracted from the rack 12.

This embodiment of the invention provides a hydraulic cylinder apparatus of reduced bulk and Weight which takes up a limited space within a jacking assembly of a marine platform. The reciprocating pin of the apparatus is sufficiently sturdy so as to carry the component of weight of a leg or barge, depending on the sequence of jacking operations, when only two such pins are used to support the leg or barge. In addition, the apparatus is adapted to be handled manually for service, installation and repair. For example, when it is desired to replace either packing 50, packing 62 or O-ring 42, first nut 69 and then bracket 29 is removed. Bolts 37 are then removed to permit disassembly of annular pads 53 and an nular retaining ring 54. Then cylinder 28 is removed and bolts 49 and mounting collar 41 are disassembled. The person servicing the assembly then has access to O-ring 42 as well as to packing 50 and packing 62. During the described sequence of disassembly, not only can each of the members removed be handled manually by one person, but, in addition, the weight of the members being disassembled does not have to be supported by the person disassembling the appartus until the member is actually being detached and removed.

Although this invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example, and that changes may be made in the details of construction and arrangement of parts without departing from the spirit and scope of the invention. For example, although the invention has been described with reference to a barge having tubular support legs, it is apparent that it may also be used with legs having other Cross-sections, such as with legs having a rectangular or triangular crosssection and with lattice-type legs. Also, although the invention has been described with reference to jacking assemblies which cooperate with apertured channel-like members on the support legs and which have yokes which envelope the support legs, it is apparent that the hydraulic cylinder apparatus of this invention may also be used with other types of marine jacking assemblies as Well as in other environments.

What is claimed is:

1. A hydraulic cylinder apparatus for engaging a support leg of a platform having associated therewith spaced vertically aligned apertures comprising (1) a pin housing,

(2) a load-engaging pin slidably mounted in said pin housing for engagement within one of the apertures associated with the support leg, and

(3) means mounted within said load-engaging pin and fixedly secured to said pin housing for reciprocating said pin in said pin housing relative to the apertures associated with the support leg.

2. A hydraulic cylinder apparatus as set forth in claim 1 wherein said means is mounted concentrically within said pin.

3. A hydraulic cylinder apparatus as set forth in claim 1 wherein said means includes a pin cylinder assembly fixedly secured in concentric relation in one end of said pin and a piston rod slidably mounted concentrically in said pin cylinder assembly, said piston rod being fixedly secured to said pin housing whereby said pin cylinder assembly is moveable relative to said piston rod.

4. A hydraulic cylinder apparatus for a support leg of a marine platform having a spaced vertically aligned aperture associated therewith comprising (1) a pin housing,

(2) a load-engaging pin which is slidably mounted on said pin housing and which has a stub shaft portion extending from one end thereof for engagement in one of the apertures associated with the support leg,

(3) a means mounted concentrically within said loadsupporting pin and fixedly secured to said pin housing for reciprocating said pin in said pin housing, said means including (a) a pin cylinder assembly fixedly secured in concentric relation within the other end of said load-supporting pin in coaxial alignment with said stub shaft portion, and

(b) a piston rod slidably mounted concentrically in said pin cylinder assembly and fixedly secured to said pin housing,

whereby said pin cylinder assembly is movable relative to said Piston rod.

5. A hydraulic cylinder apparatus as set forth in claim 4 wherein said stub shaft portion is square-shaped in cross section.

6. A hydraulic cylinder apparatus as set forth in claim 4 wherein said pin cylinder assembly and said piston rod define a first chamber radially therebetween and a second chamber coaxially therebetween for receiving pressurized fluid therein.

7. A hydraulic cylinder apparatus as set forth in claim 6 wherein said piston rod includes a pair of internal fluid passages each of which communicates between one of the chambers and the exterior of said piston rod for passing pressurized fluid therethrough.

8. A hydraulic cylinder apparatus as set forth in claim 4 which further includes a shock absorber assembly between said pin and said pin cylinder assembly at said other end of said pin for absorbing shock therebetween.

9. A hydraulic cylinder apparatus as set forth in claim 4 which further comprises a plurality of seals between said pin cylinder assembly and said piston rod for preventing passage of fluid therebetween.

10. A hydraulic cylinder apparatus as set forth in claim 4 which further includes a U-shaped mounting bracket secured to said pin housing and said piston rod.

11. A hydraulic cylinder apparatus for a support leg of a marine platform having a spaced vertically aligned apertures associated therewith comprising (1) a pin housing,

(2) a load-supporting pin which is slidably mounted in said pin housing and which has a load-supporting portion extending from one end thereof for engagement in one of the apertures associated with the support leg,

(3) means mounted within said load-supporting pin and fixedly secured to said pin housing for reciprocating said pin in said pin housing, said means including (a) a pin cylinder assembly fixedly secured within the other end of said load-supporting pin,

(b) a piston rod slidably mounted on said pin cylinder assembly and fixedly secured to said pin housing, and cooperating with said pin cylinder assembly to define a first chamber and a second chamber therebetween for receiving pressurized fluid therein, and having a pair of internal fluid passages each of which communicates between one of the chamber and the exterior of said piston rod for passing pressurized fluid therethrough,

(4) a shock absorber assembly between said pin and said pin cylinder assembly at said other end of said pin for absorbing shock therebetween, and

(5) a plurality of seals between said pin cylinder as sembly and said piston rod for preventing passage of fiuid therebetween.

12. A hydraulic cylinder apparatus as set forth in claim 11 further comprising a limit switch assembly having a limit switch secured to said pin housing and a lug secured to said pin, said limit switch including a lever mounted in the path of movement of said lug for indicating the position of said pin during movement thereof.

13. A jacking assembly for a support leg of a marine platform said support leg having associated therewith spaced vertically aligned apertures comprising (1) a pair of vertically spaced yokes,

(2) a pair of hydraulic cylinder apparatuses mounted in diametric opposition on each of said yokes, each of said apparatuses including a pin housing, a loadsupporting pin slidably mounted in said pin housing for insertion in the apertures associated with said support leg, and means mounted within said pin and fixedly secured to said pin housing for reciprocating said pin in said pin housing, and

(3) a pair of vertically disposed telescoping jacks each of said jacks being connected to respective said hydraulic cylinder apparatuses of each of said yokes for moving said yokes relative to each other whereby said jacking assembly is movable along the support leg.

14. A jacking assembly as set forth in claim 13 wherein each of said yokes is formed of a pair of semi-circular members, each of said semi-circular members having a center which is ofiset from the center of the other of said semi-circular members.

15. A jacking assembly as set forth in claim 13 wherein each of said apparatus is mounted at a slight downward angle relative to a horizontal plane passing through the support leg.

16. A jacking assembly as set forth in claim 13 wherein said means is mounted concentrically within said pin,

17. A jacking assembly for a support leg of a marine platform said support leg having associated therewith spaced vertically aligned apertures comprising (1) a pair of vertically spaced yokes,

(2) a pair of hydraulic cylinder apparatuses mounted in diametric opposition on each of said yokes, each of said apparatuses including (a) a pin housing,

(b) a load-supporting pin which is slidably mounted in said pin housing and which has a load-supporting portion extending from one end thereof for insertion in the apertures associated with said support leg,

(0) means mounted within said load-supporting pin and fixedly secured to said pin housing for reciprocating said pin in said pin housing, said means including (i) a pin cylinder assembly fixedly secured within the other end of said load-supporting pin,

(ii) a piston rod slidably mounted on said pin cylinder assembly and fixedly secured to said pin housing, and cooperating with said pin cylinder assembly to define a first chamber and a second chamber therebetween for receiving pressurized fluid therein, and having a pair of internal fluid passages each of which communicates between one of the chambers and the exterior of said piston rod for passing pressurized fluid therethrough,

(d) a shock absorber assembly between said pin and said pin cylinder assembly for absorbing shock therebetween, and

(e) a plurality of seals between said pin cylinder assembly and said piston rod for preventing passage of fluid therebetween, and

References Cited UNITED STATES PATENTS 904,528 11/ 1908 Hamilton et al. 3,007,317 11/1961 Suderow 61-46.5 3,257,099 6/ 1966 Merritt 254105 OTHELL M. SIMPSON, Primary Examiner.