US3465807A - Retractable rig for operating hatch covers - Google Patents

Description

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Sept. 9, 1969 u. J. BEAS RETRACTABLE RIG FOR OPERATING HATCH COVERS Filed Dec. 26, 1967 5 Sheets-Sheet l mvsmok. unamv J- BEAS ATTORNEYS.

Sept. 9, 1969 u. J. BEAS RETRACTABLE RIG FOR OPERATING HATCH COVERS' 5 Sheets-Sheet 2 Filed Dec. 26, 1967 INVENTOR. URBAN .1. 5545 BY 9{ &7

ATTOQNEYS.

Sept. 9, 1969 u. J. BEAS RETRACTABLE RIG FOR OPERATING HATCH COVERS Filed Dec. 26, 1967 5 Sheets-Sheet I u /////////rrI// FIGS FIG. 7

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INVENTOR. URBAN J 85115 7 ATTORNEYS.

Sept. 9, 1969 u. J. BEAS 3,465,807

RETRACTABLE RIG FOR OPERATING HATCH COVERS 5 Sheets-Sheet 4 Filed Dec. 26, 1967 FIG. 8

I/VVE'IVTUZ URBAN J. BEAS Sept. 9, 1969 u. J. BEAS 3,465,807

RETRACTABLE RIG FOR OPERATING HATCH COVERS Filed Dec. 26, 1967 5 Sheets-Sheet 2,-

A T TORNE Y5 Q o 2 L 5. i 3 8w: E

g 1 1 $2 $31 M Z U 1 81 mvv aw 3v Q\ L. W. O a

United States Patent U.S. Cl. 160-188 18 Claims ABSTRACT OF THE DISCLOSURE A retractable rig for operating hatch covers on cargo vessels, barges, or the like. The rig comprises a boom and linkage which are retractable when not in use. In a preferred embodiment, the rig is retractable into a channel in the hatch cover such that in the retracted position, the rig does not project above the surface of the hatch cover. A winch is provided to operate the boom and linkage and the winch is also preferably retractable below the surface of the hatch cover. Increased mechanical advantage is obtained by locating the effective axis of rotation of the boom forward of the axis of rotation of the hatch cover and by using a rope and pulley arrange ment as the linkage between the winch and boom.

This application is a continuation-in-part of Ser. No. 608,870, filed Jan. 12, 1967 and now abandoned.

This invention relates to a new and improved rig for operating hatch covers, and more particularly to a new and improved retractable rig for opening and closing hatch covers on cargo vsesels, barges, or the like.

Cargo-carrying vessels such as cargo ships, barges and the like, are commonly equipped with a hatch cover comprising a single section pivotally mounted along one edge of the hatchway, or a plurality of successive sections pivotally interconnected to comprise an accordion-like row with the end-most, or first, section pivotally connected on an edge of the hatchway, so that the hatchway may be opened by folding the sections against each other in succession. In applications, such as on cargo vessels, where space is not as critical, the hatch cover may be opened and closed by means of one of several systems. One such system utilizes motors associated with the hatch cover itself, whereby the hatch cover is opened and closed by energizing the motors from an electrical source of power located on the vessel. Another such system utilizes a power winch mounted on the deck of the vessel having a rope or the like secured to the hatch cover. Where the winch is not used exclusively to open and close the hatch cover, it is necessary to manually secure a rope to the cover each time it is opened. A further system utilizes the hoist associated with the power boom. All of the above systems generally utilize electrical power. In applications where electrical power is not available, manually operable winches permanently mounted on the deck may be provided. These manually operated winches suffered the disadvantage that mechanical advantage could only be ob stantial height above the deck.

Great interest is presently being shown in containerized cargo vessels wherein a plurality of barges are stacked one upon the other within the hold of the vessel. In order to maximize the number of barges that may be vertically stacked within a given hold depth, it is desirable that the vertical depth of an individual barge be utilized to the fullest extent for the storing of cargo. It is also desirable that the upper surface of the barge be as free as possible from projections or the like. It is also desirable to provide 3,465,807 Patented Sept. 9, 1969 a rig for opening and closing the hatch covers on the barge which is either operable manually or automatically by means of a suitable power means.

According to the present invention, a rig for opening and closing hatch covers is provided which is especially adapted for use in applications where space is critical such as barges stacked within a containerized cargo vessel. In general, the rig of the present invention comprises a retractable boom and linkage which are adapted to be stowed substantially horizontally when not in use. In a preferred embodiment, the boom and linkage are stowed within the hatch cover when not in use and a winch, operable either manually or automatically, is provided, associated with the boom. In such case, the winch is also preferably retractable and is stowed below the plane of the upper surface of the hatch cover. A self-operating energy accumulator device may also be provided to achieve greater mechanical advantage in opening the hatch cover. Further mechanical advantage may be obtained by locating the effective axis of rotation of the boom in advance of the axis of rotation of the hatch cover and by using a rope and pulley arrangement as the linkage between the boom and the winch.

It is thus an object of the present invention to provide a new and improved rig for operating hatch covers which may be simply and efiiciently operated.

It is a further object of the present invention to provide a new and improved rig for operating hatch covers which is easily extended or retracted and which occupies a minimum amount of space when in the retracted position.

It is yet another object of the present invention to provide a new and improved rig for operating hatch covers which may be operated either manually or automatically.

It is still another object of the present invention to provide a new and improved rig for operating hatch covers which, in conjunction with an energy accumulator device, is adapted to permit easy opening of comparatively heavy hatch covers.

It is also an object of the present invention to provide a new and improved rig for operating hatch covers which may be stored within and locked within a hatch cover in the open position when the hatch cover has been opened by external means.

Other and further objects of the present invention will be evident to those skilled in the art from the following description and drawings wherein:

FIG. 1 is a plan view of a preferred embodiment of the rig of the present invention in association with a hatch cover mounted on a barge;

FIG. 2 is a side elevational view of the embodiment of FIG. 1;

FIG. 3 is a side elevational view showing one part of the hatch cover retracted and the other part of the hatch cover extended but with the rig of FIG. 1 partially extended;

FIG. 4 is a partially sectional elevational view taken along line 44 of FIG. 1;

FIG. 5 is a partially sectional elevational view taken line 5-5 of FIG. 1;

FIG. 6 is a partially sectional elevational view taken along line 66 of FIG. 5;

FIG. 7 is a partially sectional elevational view taken along line 77 of FIG. 5;

FIGURES 8 and 8a are side elevational views of another embodiment of the rig of the present invention;

FIG. 9 is a partially sectional plan view of the rig of FIGS. 8 and 8a; and

FIG. 10 is a partially sectional elevational view taken along line 10-10' of FIG. 9.

Referring now to the figures, there is shown in FIGS. 1 and 2 a hatch cover generally connoted by the numeral 10 comprised of a plurality of sections 12, 14, 16 and 18. Sections 12 and 14 are pivotally connected together by hinges 20, as are sections 16 and 18. Paired sections 12, 14 and 16, 18 are respectively adapted to fold to a vertical position to the left and to the right when hatch cover 10 is fully opened.

Hatch cover 10 is pivotally mounted on coaming 22 of barge 26 by means of arms 24 rigidly connected to sections 12 and 18, arms 24, in turn, being pivotally mounted on brackets 27 rigidly secured to coaming 22. Energy accumulator devices 28, to be described in greater detail hereinafter, are also provided.

The opening and closing of hatch cover 10 is facilitated by means of wheels or rollers 30 respectively mounted adjacent the ends of sections 14 and 16. Wheels 30 are adapted to roll on tracks 32 provided on coaming 22. Tracks 32 have inclined portions 36 to facilitate the closing of hatch cover 10 through the operation of gravity thereon. As shown in FIG. 1, when hatch cover 10 is closed, wheels 30 mounted on section 16 are displaced laterally with respect to wheels 30 mounted on section 14.

A pair of retractable hatch cover operating rigs 38 and 38 are provided for opening and closing the halves of hatch cover 10. As shown more clearly in FIGS. 3 and 4, rig 38 comprises a boom 40 pivotally mounted at one end to the coaming of barge 26 by means of mounting bracket 42. Bracket 42 is mounted intermediate energy accumulator devices 28. Secured to the free end of boom 40 is a linkage 44 comprising rope 46 and bar 48. One end of rope 46 is secured to pin 50 positioned at the end of boom 40. The other end of rope 46 is secured to pin 52 mounted at the free end of bar 48. The other end of bar 48, in turn, is rotatably secured to member 54 of section 12.

As shown in FIGS. 1 and 4, section 12 is provided with a slot 56. When rig 38 is in its retracted position, boom 40 and linkage 44 rest within slot 56 below the upper surface of section 12. Supporting member 58 mounted on member 60 of section 12 supports boom 40 in the re-- tracted position. As shown in FIG. 4, the height of mount ing bracket 42 is preferably substantially equal to or less than the height of hatch cover 10, so that no portion of bracket 42 protrudes above the plane of the upper surface of cover 10.

A winch 62 mounted on collapsible winch supporting fixture 64 is provided with a rope 66, the end of which is secured to pin 68 mounted above pin 50 on the free end of boom 40. In the retracted position, the end of rope 66 lies within slot 56 of section 12.

Fixture 64 comprises members 70 and 72 pivotally mounted at their lower ends to the deck of barge 26, winch 62 being mounted at the end of member 70. When rig 38 is in the retracted position, member 70 is secured to the lower portion of member 72 so that winch 62 does not protrude above the plane of the upper surface of hatch cover (see FIG. 2). When rig 38 is in the extended position, however, member 70 is pinned to the upper portion of member 72 to facilitate operation of winch 62.

Operation of rig 38 in opening hatch cover 10 is as follows: When hatch cover 10 is closed, rig 38 is retracted with boom 40 and linkage 44 lying within slot 56. Fixture 64 is likewise retracted such that no portion of rig 38 projects above the upper plane of hatch cover 10. When it is desired to open hatch cover 10, fixture 64 is extended to raise winch 62. Winch 62 is then operated either manually or automatically to reel in rope 66, thereby to raise boom 40 and make taut linkage 44. This is shown more clearly on the right-hand side of FIG. 3, wherein hatch cover 10 is closed, but rig 38' has been extended.

Further operation of winch 62 to reel in rope 66 causes boom 40 to rotate, said rotation of boom 40 causing rotation of section 12 by means of linkage 44. Due to the hinged interconnection between sections 12 and 14, rotation of section 12 causes the hinged end of section 14 to be lifted, thereby to cause section 14 to be folded upon section 12 in a substantially vertical position. The free end of section 14 rolls along tracks 32, thereby facilitating the folding of hatch cover 10 out of the way of the hatchway of barge 26.

Chains 74 are provided to limit the rotation of section 12, chains 74 being secured at one of their ends to section 12 and at the other of their ends to the deck of barge 26. Latches 76, pivotally mounted on section 14, are adapted to latch on to latching pins 78 on section 12 when sections 12, 14 are in the stowed or open position. Latches 76 prevent closing of sections 12, 14.

Closing of hatch cover sections 12 and 14 is accomplished by first unlatching latches 76 from pins 78 and unreeling rope 66 through the operation of winch 62. Through the action of gravity, the weight of sections 12 and 14 causes section 14 to roll down inclined portions 36 of tracks 32. Further unreeling of winch 62 causes sections 12 and 14 to be extended to the closed position and thereafter lowering of linkage 44 and boom 40 into slot 56. Fixture 64 is then separately retracted, thereby completing the stowing of rig 38.

Energy accumulator devices 28 are preferably provided to reduce the mechanical power required of winch 62 to raise hatch cover 10. Referring more particularly to FIGS. 5, 6, and 7, section 12 is pivotally mounted on coaming 22 of barge 26 by means of arms 24 rigidly connected to the rear edge of section 12, mounting brackets 27 rigidly connected to coaming 22, and pivot pins 84 passing through bores in arms 24 and brackets 27. A torsion spring 86 is rigidly connected at one end to an arm 24 by means of socket 88 provided on arm 24. Spring 86 is rigidly mounted at its other end in a mounting bracket 90 comprising socket 92, and support member 94 mounted on coaming 22.

As shown more clearly in FIG. 6, torsion spring 86 comprises a plurality of flat strips or blades 96 assembled along their major faces in order to constitute a bundle of substantially rectangular and preferably square cross-section. As shown, six blades 96 comprise spring 86. However, it will be understood that any appropriate number may be used. The end of spring 86 is secured in socket 92 by means of four wedging blocks or like elements 98 disposed within socket 92. The other end of spring 86 may be mounted in socket 88 in similar manner.

As shown, torsion spring 86 is axially aligned with the pivotal axis of section 12. Spring 86 is so mounted with respect to section 12, as to be free of any torsional torque when cover 10 is stowed in the open position (in the position shown at the left of FIG. 3). When sections 12, 14 are moved to the closed position, torsion spring 86 is twisted through an angle of about 90 by the weight of said sections. The torque thus accumulated in spring 86 is subsequently available for mechanically assisting winch 62 during the next opening of cover 10. This mechanical assist provided by spring 86 reduces the mechanical power required from winch 62 in opening cover 10.

As shown in FIG. 1, a pair of energy accumulator devices 28 are provided for each half of cover 10, an individual device 28 being provided for each pivotal connection of a section of cover 10 to coaming 22 of barge 26. Each accumulator device 28 is preferably substantial ly identical to that described hereinabove with respect to FIGS. 5, 6, and 7, and is connected to an appropriate section of cover 10 in similar manner.

As is also shown in FIG. 1, a separate rig 38 is provided for each half of cover 10. Although rig 38 has been described hereinabove more particularly with respect to sections 12 and 14, it will be understood that rig 38' associated with sections 16 and 18 is preferably substantially identical in structure and operation.

Dogs 100 provided along the edges of the sections of cover 10 are adapted to be acted upon by closing devices (not shown) which maintain cover in the closed position during transit.

Referring now to FIGURES 8-10, there is shown another embodiment of the retractable rig of the present invention. According to this embodiment, a retractable rig 110 is provided comprising a boom 112 and linkage 114. As described hereinabove, boom 112 is preferably pivotally mounted on a bracket 115 substantially midway the width of hatch cover 10. Boom 112 comprises members 116 and 118, member 116 being pivotally connected to member 118 by pin 120. The other end of member 118 is pivotally connected to bracket 115 by pin 122. As will be described in greater detail hereinafter, the pivotal axis A of member 118 about bracket 115 is positioned above the pivotal axis B of hatch cover section 12 about brackets 27.

A sheave or pulley 124 is pivotally connected at the free end of member 116 of boom 112 by means of pin 126. An idler pulley 128 is pivotally mounted on boom memher 116 below sheave 124. Rope 66, wound about winch 64, is passed around sheave 124 and anchored to the deck of barge 26 by means of bar 130, which is secured at one end to the free end of rope 66 and pivotally mounted at the other end to the deck of barge 26.

Linkage 114 comprises members 136, 138, and 140, and is connected between the free end of boom member 116 and member 134 of batch cover section 12. Member 136 is comprised of a pair of parallelly arranged members 136a and 136b. Members 136a and 136b are pivotally connected at one end to the free end of boom 112 and at the other end to linkage member 138. In like manner, linkage member 140 comprises a pair of parallelly arranged members 140a and 140b, which are pivotally connected at one end to member 138, and at the other end to member 134 of batch cover section 12. As shown more particularly in FIGS. 9 and 10, members 136 and 138 are spaced apart by a distance somewhat greater than the thickness of member 138, such that when rig 110 is in the retracted position, stowed within hatch cover section 12, member 138 will telescope partially into member 136, In similar manner, members 140a and 14017 are spaced apart for a portion of their length a suflicient distance to permit telescoping of member 138, as well as member 136 thereinto, when rig 110 is retracted.

A pair of locking studs 142 and 144 are provided on boom member 116 and a pair of complementary locking studs 146 and 148 are provided within channel 150 of hatch cover section 12. Studs 142 and 144 are respectively spaced horizontally from studs 146 and 148 and as will be described in greater detail hereinafter, studs 142 and 144 will engage studs 146 and 148 when hatch cover sections 12 and 14 are raised to an open position by external means, thereby securing rig 110 within section 12.

Mounted on the deck of barge 26 is a support 152. Support 152 is positioned at the pivotal connection of boom members 116 and 118, and is adapted to support member 118 in a substantially horizontal position, as well as to provide a pivot point for member 116 when rig 110 is extended to open hatch cover sections 12 and 14.

In operation, reel 64 is cranked to reel in rope 66. By having rope 66 passed over sheave 124, and anchored to the deck of barge 126, the mechanical advantage of the rig is increased over the rig described hereinabove and shown in FIGURES 1-4, where rope 66 was merely attached to the end of the boom. In the arrangement shown, the advantage is increased twofold. The mechanical advantage may be increased even further by using additional sheaves which are mounted on the boom and/or the deck, and about which rope 66 is passed. For example, if an additional sheave is secured to the barge deck and rope 66 is passed about sheave 124, about the additional sheave secured to the deck, :and the end of the rope is secured to the boom, the mechanical advantage will be increased three-fold. In this manner, heavier hatch covers may be raised with no increase in force applied to the winch.

As described hereinabove, rope 66 passes over idler pulley 128 when rig is retracted. As rope 66 is reeled in, thus causing member 116 to pivot on support 152, the angle formed between rope 66 and member 116 will increase, until the point is reached where rope 66 will no longer be in contact with idler pulley 128. This point will be reached before hatch cover section 12 is caused to be lifted, so that during the lifting operation, rope 66 will be substantially linear between reel 64 and sheave 124.

As member 116 is caused to pivot, linkage 114 is extended, until such point when members 136, 138, and are aligned. At this point (see right-hand side of FIG. 8) linkage 114 is fully extended and further rotation of member 116 acts to raise cover section 12 by means of linkage 114.

Member 116 is rotated until sections 12 and 14 are substantially vertical and have reached the open position (see left-hand side of FIG. 8). As described hereinabove, chains 74 are provided to limit the further rotation of section 12, and latches 76 pivotally mounted on section 14 are adapted to latch onto latching pins 78 on section 12 to prevent closing of sections 12 and 14.

When it is desired to close sections 12 and 14, latches 76 are disengaged from pins 78, and rope 66 is unreele Through the action of gravity, the weight of sections 12 and 14 causes section 14 to roll down inclined portions 36 of tracks 32. After sections 12 and 14 have been extended to the closed position, further unreeling of rope 66 causes linkage 114 to telescope into channel of section 12, and to cause boom member 116 to also telescope into channel 150. As described hereinabove, energy accumulator means 28 are preferably provided to reduce the mechanical power required of Winch 64 to raise hatch cover 10.

By shifting the effective pivot point of the boom, i.e., the pivot point of boom member 116, forward of the pivot point of the hatch cover, increased mechanical advantage is obtained, thus further reducing the force of the winch required to open the hatch cover.

As described hereinabove, external means such as a dockside crane may be provided to open hatch cover 10. In such cases, it is desirable that rig 110 be retained within slot 150 of section 12 when the cover is fully opened. Due to the tendency of member 116 to fall out of slot 150 when section 12 is in a vertical position, locking studs 142, 144, 146, and 148 are provided, and the pivotal axis of member 118 is displaced above the pivotal axis of the hatch cover. As cover 12 is rotated, the weight of member 116 will maintain it in channel 150, and will cause member 116 to remain substantially linearly aligned with member 118 and to pivot about bracket 115. However, as cover 12 is raised, there will be a relative sliding movement between boom member 116 and the hatch cover section, so that locking studs 142 and 144 slide under studs 146 and 148. When cover 12 is raised to its full vertical position, locking studs 142 and 144 will have reached the positions shown in dotted lines in FIG. 9 and will be substantially opposite studs 146 and 148. Thus boom 112 will be locked within cover section 12.

Although preferred embodiments of the rig of this invention have been shown and described hereinabove, it will be understood that modifications thereof within the knowledge of those skilled in the art may be made and are still considered to be within the scope of the present invention. Thus, although the boom (40, 112) has been shown pivotally mounted on coaming 22 midway of section 12, the boom may also be mounted anywhere along the lateral width of coaming 22 with the linkage (44, 114) suitably connected to section 12. Moreover, it is not required that boom 40 be mounted on coaming 22 substantially at the pivotal axis of section 12. Thus boom 40 could also be mounted behind coaming 22 on the edge of barge 26. In like manner, although the boom and linkage have been shown and described as retracting into a slot formed in section 12 in order to dispose them below the surface of cover to provide a minimum of height of barge 26, it will be understood that where height limitations are not as critical, the boom and linkage could also rest on the upper surface of cover 10, thus obviating the necessity for a slot in section 12. Although only a single boom and linkage assembly has been shown and described as associated with each hatch cover half, two or more boom and linkage assemblies operated individually or in tandem may also be provided in place thereof.

It will also be understood that although linkage 44 has been shown and described as comprising a rope and bar connected together, bar 48 could be eliminated, with a single rope, chain or the like, extending between boom 40 and section 12. In such a case, it is desirable that some means be provided to cause the rope to fall into slot 56 when boom 40 is lowered thereinto. Such rope slackening means are well known in the art, and could, for example, be a guide rope. Similarly, linkage 114 may comprise more or less than the three members shown in FIGS. 8-40. In this application, the term linkage is meant to refer to any means such as ropes, chains, etc., for connecting the boom to the hatch cover section.

Although a specific form of mounting fixture for winch 62 has been described and shown, it will be understood that any suitable mounting fixture could be provided, and still be considered within the present invention. Although it is desirable that the mounting fixture for winch 62 be collapsible, this is not required and a fixture rigidly mounting winch 62 to barge 26 may be used. It will also be understood that winch 62 may be operated manually or operated automatically by means of a suitable power drive.

Although the rig has been described as associated with an energy accumulator device, it will be understood that rig 38 may be operable without such a device. In such case, it is only necessary that the power of winch 62 be increased to make up for the mechanical advantage provided by device 28. Although a specific form of device 28 has been described, other forms and modifications known to those skilled in the art may be substituted therefor. It is only necessary that such a device provide mechanical assist in opening the hatch cover 10. Other forms of such device are, for example, described in copending US. application S.N. 346,279 for Closing Device For Hatch Covers and the Like now US. Patent No. 3,389,739.

The retractable rig of the present invention may be used with hatch covers which are either weather-tight or water-tight when closed.

Although a preferred embodiment of the present invention has been described hereinabove and shown in the drawings, it will be understood that modifications thereto and other embodiments evident to those skilled in the art are also considered to be within the present invention. Therefore, the scope of this invention should be determined from the following claims taken in the light of said description and drawings.

What is claimed is:

1. In a vessel having a deck, a hatch in said deck and a hatch cover having at least one section pivotally mounted at the edge of the hatch, the improvement comprising a retractable rig comprising a retractable boom assembly connected to said hatch cover section and adapted to be retracted when not in use and a retractable winch assembly to operate said hatch cover, said winch assembly being mounted on a retractable fixture which is adapted to be retracted when not in use.

2. The retractable rig of claim 1 including energy accumulator means associated with said rig and connected to said hatch cover section in such manner as to mechanically assist the opening of said hatch cover.

3. The retractable rig of claim 1 including drive means connected to said winch assembly for driving said assembly.

4. In a vessel having a deck, a hatch in said deck and a hatch cover having at least one section pivotally mounted at the edge of the hatch, the improvement comprising a retractable rig comprising boom pivotally mounted near the rear of said hatch cover section, a first linkage connected between said boom and said hatch cover section, a Winch and a second linkage Wound up on said winch and connected to said boom, said winch being mounted on a retractable fixture mounted on said deck to the rear of said boom, said boom and first linkage being adapted to be retracted to a substantially horizontal position when not in use and said fixture being adapted to be retracted when not in use.

5. The retractable rig of claim 4 wherein said boom is mounted substantially midway the width of said hatch cover section and said linkage is connected to said hatch cover section substantially at the edge opposite said pivotally mounted edge, substantially midway the width thereof.

6. The retractable rig of claim 4 wherein said first linkage comprises a rope and bar assembly.

7. The retractable rig of claim 4 wherein said first linkage comprises a plurality of members connected together.

8. The retractable rig of claim 4 including an energy accumulator device associated with said rig and connected to said hatch cover section in such manner as to mechanically assist the opening of said hatch cover by said rig.

9. The retractable rig of claim 4 wherein said boom comprises first and second members respectively having first and second ends, said members being pivotally connected together at their respective first ends, and including a support mounted to the front of the pivotal axis of said hatch cover section, said first end of said first member resting on said support, said support providing a pivot point for said second member when said boom is extended.

10. The rig of claim 9 wherein said second end of said first member of said boom is pivotally mounted and has a pivotal axis above the pivotal axis of said hatch cover section, but in the same vertical plane thereas.

11. In a vessel having a deck and a hatch in said deck the improvement comprising a hatch cover assembly having at least one hatch cover section pivotally mounted at the edge of said hatch, a boom pivotally mounted near the rear of said section, a first linkage connected between said boom and said hatch cover section, a winch, a retractable fixture mounted on said deck, said winch being mounted on said fixture, a second linkage wound up on said winch and connected to said boom, said boom and first linkage being adapted to be retracted to a substantially horizontal position when not in use and said winch and fixture being adapted to be retracted when not in use.

12. The hatch cover assembly of claim 11 including an energy accumulator device mounted on said deck and connected to said hatch cover section in such manner as to mechanically assist the opening of said hatch cover by said rig.

13. The hatch cover assembly of claim 11 wherein said hatch cover section is provided with a slot and said boom and said first linkage are adapted to be retracted into said slot when not in use.

14. The hatch cover assembly of claim 11 including drive means connected to said winch for driving said winch.

15. The hatch cover assembly of claim 11 wherein the pivotal axis of said boom is coaxial with the pivotal axis of said pivotally mounted hatch cover section.

16. The hatch cover assembly of claim 11 wherein the pivotal axis of said boom is forward of the pivotal axis of said hatch cover section.

17. The hatch cover assembly of claim 13 wherein the pivotal axis of said boom is above the pivotal axis of said hatch cover section and wherein said boom is provided with locking means and said hatch cover section is provided with complementary locking means positioned within said slot adjacent said boom locking means, such that when said hatch cover section is opened by external means, said boom will slide within said hatch cover section to cause said boom locking means to engage said hatch cover section locking means to maintain said boom and linkage in said hatch cover section in the open position.

18. The batch cover assembly of claim 11 wherein said boom comprises first and second members respectively having first and second ends, said members being connected together at their respective first ends and including a support mounted on said deck to the front of the pivotal axis of said hatch cover section, said first end of said first member resting on said support, said support providing a pivot point for said second member when said boom is extended.

References Cited UNITED STATES PATENTS Frey 160-193 Brazier et a1 49347 Whittelsey 114-201 X Frost 141 Honey 52-119 X Floehr 105-377 Stransky 160188 X Dahlin 160-193 Learmont 21477 Kummerman et al. 160188 US. Cl. X.R.

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