US3057484A - Rigging - Google Patents

Description

Oct. 9, 1962 v. H. TREvlsAN 3,057,484

RIGGING Filed June 26, 1961 2 Sheets-Sheet 2 United States Patent O 3,057,484 RIGGING Virgil H. Trevisan, 729 Engle St., Chester, Pa. Filed June 26, 1961, Ser. No. 119,551 4 Claims. (Cl. 212-3) This invention relates -to rigging of a system for transferring a load from a first rest location to a nearby rest location by means of a swinging boom, as in the loading and unloading of a ship, for example.

Rigging for existing practical cargo-transferring systems having a load-positioning lboom includes, in the tackle for controlling the position of the boom, one or more vangs, which extend from the boom head toward the deck. In addition such rigging includes a topping lift. These items of tackle are secured at fixed locations, and Variation in their respective lengths can swing the boom azimuthally yand can raise or lower the boom, the foot or heel of which is pivotally stepped at another fixed location. Great care must be taken to adjust the changing lengths of the tackle so as to keep from losing the boom, as may happen in some conventional rigs in the absence of proper angular control or as may be occasioned by failure of tackle through overstressing.

A primary object of the present invention is provision of a cargo-'transferring system wherein the boom thereof is swung and simultaneously raised or lowered by change in effective length of only one item of tackle.

An object of the invention is elimination of vangs in a cargo -transferring system.

Another object is provision of improved rigging for a cargo-transferring system of boom type by use of a pair of topping lifts secured at fixed flanking locations.

An object is ysimplified rigging for a cargo-transferring system in the interest of economy in manufacture and trouble-free operation and maintenance.

A further object is provision of a cargo-transferring system in which a laden boom need never be raised in swinging to -a desired azimuthal position.

Other objects of this invention, together with means and methods for attaining the various objects, will -be apparent from the following description and the accompanying diagrams.

FIG. l is a perspective vview of a cargo-'transferring system according to the present invention;

FIG. 2 is a schematic -side elevation of the apparatus of FIG. l, with an alternative position of the and rigging shown in broken lines;

FIG. 3 is a schematic front elevation corresponding to the placement of elements in FIG. 2;

FIG. 4 is a plan view correspond-ing to the placement of elements in the preceding elevational views;

lFIG. 5 is a schematic front elevation of the system loading cargo; and

FIG. 6 is -a schematic front elevation of the system unloading cargo.

In general, the objects `of the present invention lare accomplished -by providing, in a cargo-transferring system, a method of swinging a pivotally supported upstanding boom and simultaneously lowering the boom head, comprising restraining the boom head only by a plurality of topping lifts of variable length secured thereto and spaced apart flanking the Iboom, then lengthening the topping lift on one side, while maintaining the other topping lift -at essentially constant length, whereby the boom head will swing down and away from that side on which the ytopping lift is lengthened.

The invention contemplates, as apparatus for practicing such vangless method, a plurality of cables secured as topping lifts -to the yboom head and secured, spaced apart from one Ianother, also to individual supporting means fixed ata level above the level of the boom 3,057,484 Patented Oct. 9, 1962 ICC Z heel, the topping lifts being variable in length to vary the position of the boom.

FIG. 1 shows in perspective a preferred embodiment of the cargo-transferring system of the present invention. Upstanding mast 11, which is surrounded by raised winch platform 12 at its base, has o-utrigger 13 at its top, in a T configuration. Hatchway 14 in deck 15 appears directly 4ahead of the mast and the winch platform. Boom 21 is supported universally at its foot on pivot pin 22 in swivel 23 mounted in boom step 24. Boom head 31 has upper cargo fall block 32 fastened to it and depending therefrom. Cargo fall 33, interconnecting the upper cargo fall `block and lower cargo fall 'block 34, extends the length of the boom, passing through fair-lead 35 aiixed to the boom intermediate its ends. After passing about lboom step lead vblock 36, the cargo fall winds onto cargo fall winch 37, which is mounted on the winch platform :and powered conventionally. Load or cargo 41 is supported in sling 42 secured to hook 43, which depends from the lower cargo fall block.

Outrigger 13 carries on its near face a pair of topping lift lead blocks close to each of its opposite ends, outboard upper topping lift lead blocks 51, 51', and lower topping lift lead blocks 52, 52 (the primed reference numerals Yindicating elements at the right side and corresponding to like elements designated by unprimed reference numerals at the left side of the view), and inboard topping lift lead blocks 53, 53 near the junction with the mast itself. Topping lift lead blocks '54, 54' are secured to the boom head. Topping lifts 55, 55 at the respective sides run `about the various topping lift lead blocks and extend down -the mast to wind onto conventionally powered, individually operated topping Winches 56, 56 mounted on the sides of the mast. The various blocks lare swivel-mounted to allow for changes in the orientation of the blocks during operation of the system.

The method of operation of this system `according to the present .invention will be further -apparent from the remaining views and the description thereof. FIGS. 2, 3, and 4 .show in schematic fashion in side :and front eleva-tion :and plan, respectively, the system shown `in greater detail in FIG. l but lwith the outboard side reversed (i.e., at the left), such as is permitted, for example, by optional lcenter mounting of the boom approximately equidistant between the sides of lthe vessel. The boom is represented in solid lines at a topped (i.e., boom head at or near level of Outrigger) inboard position, and in broken lines in a lowered outboard position. The effective lengths of the respective topping lifts are `approximately equal in the inboard position, andmost unequal in the outboard position. Of course, the boom may 'be topped outboard (instead of inboard), .such a position being shown in FIG. 5 in which the outboard `side happens to lie on the right :as suggested ,in FIG. 1'.

It is apparent from these views that lengthening one of the topping lifts will permit (and, indeed, cause) the boom to swing under its own weight, and that of any cargo supported by it, away from the side at which the topping lift is lengthened. Shortening of that same topping lift to like extent will return the boom to its original position. Shortening both topping lifts by the same amount will top the boom at substantially its existing azimuthal angle. Lengthening -both topping lifts by the same amount will lower the boom accordingly, without significantly altering its azimuthal orientation. Lengthening one topping lift while shortening the other topping lift a like amount will luff rthe boom (i.e., travel the boom head in an arc of azimuth at a constant level above the deck).

FIGS. 5 and 6 are schematic front elevations of various positions or attitudes of the boom in loading and unloading, respectively. As shown in FIG. 5, loading `begins with the boom topped outboard. After the load is secured to the cargo fall and lifted thereby clear of the deck (lifted position not shown) topping lift 55 (i.e., the outboard topping lift) is lengthened by appropriate rotation of topping winch 56 (v. FIG. l), whereupon the boom swings the load inboard and downward (broken lines). When the load is so positioned it is readily lowered through the hatchway (v. also FIG. l) by, and released from, the cargo fall. The boom then is returned to the outboard position by shortening topping lift 55. Throughout this operation no change in the effective length of topping lift 55 has been necessary. Of course, topping lift 55 is longer than topping lift 55 in the illustrated outboard position (both being about the same length in the inboard position).

Unloading, which is much the reverse of loading, is shown similarly in FIG. 6, in which `the relative positions of the boom are reversed from those in FIG. 5. The boom is topped inboard, and the load is raised from the hold through the hatchway and clear of the deck (raised position not shown). The boom is swung outboard (and down) by lengthening the inboard topping lift (i.e., topping lift 55) to position the load dockside (broken lines). After release of the load from the cargo fall, the boom is returned to its original position by shortening the previously lengthened topping lift.

It will be noted that in the described and illustrated practice of this invention the load is raised only by the cargo fall, never by a topping lift. No vang must be lengthened or shortened to move the laden (or unladen) boom. Stress on the structural components is minimized. For best results the spacing of the points at which the topping lifts are secured by their lead blocks to the Outrigger should be at least about one-fourth the length of the boom, which itself is normally forty to forty-five percent longer than the height of the Outrigger above the boom step itself. The points at which the lead blocks are mounted on the Outrigger should be fixed, so that they lie at all times on a constant straight line extending laterally along the Outrigger (and through the mast head). Such an arrangement should not be confused with derricks or similar cargo-lifting systems in which one or more of the boom-supporting locations pivot or otherwise move.

The above description of the structure of a specific embodiment of this invention does not preclude minor modifications compatible with the inventive concept. For example, the illustrated tackle may be simplified or elaborated, as by increasing or decreasing the number of sheaves per block. A pair of king posts, with or without a truss joining their tops, may be substituted for the illustrated single mast and Outrigger; of course, the respective topping lifts would be secured to the respective king posts or similarly laterally spaced portions of the truss. A pair of like installations can be erected side by side for use either individually or for burtoning, if desired.

This invention permits loading and unloading of cargo yto be controlled entirely by one man, inasmuch as normally only one winch is operated at once. This contrasts sharply with the usual crew of a half dozen or more required for simultaneous operation of Winches (necessitating careful surveillance and coordination) in conventional rigs. There is no risk of losing the boom, and the full extent of convenience and security in operation can only be suggested here. The various benefits of the present invention will be most apparent and will accrue to those who undertake to practice it.

The claimed invention:

1. Method of swinging a pivotally supported upstanding boom and simultaneously lowering the boom head, comprising restraining the boom head only by a plurality of topping lifts of variable length secured thereto and spaced apart flanking the boom, then lengthening the topping lift on one side, while maintaining the other topping lift at essentially constant length, whereby the boom head will swing down and away from that side on which the topping lift is lengthened.

2. In a vang-less cargo-transferring system having a mast, a boom pivotally mounted at its heel, a cable extending as a cargo fall substantially the length of the boom and adapted to depend to variable extent from the boom head, and rigging means for controlling the movement of the boom, the improvement comprising a plurality of cables secured as topping lifts to the boom head, a plurality of mast-supported boom-restraining means spaced laterally from one another by about one-fourth the boom length and at a level about two-thirds of the boom length above and anking the boom heel, and means for varying the length of each topping lift independently of the other.

3. Method of transferring cargo according to claim l from an inboard location ahead of the boom heel to an outboard location spaced laterally therefrom, comprising adjusting the topping lifts to approximately the same length and thereby positioning the boom head above the cargo, securing the cargo to the cargo fall, shortening the cargo fall to raise the cargo toward the boom head, then lengthening the inboard topping lift, while maintaining the outboard topping lift at essentially constant length, and thereby swinging and lowering the boom head to position the cargo, and releasing the cargo.

4. Method of transferring cargo according to claim 1 from an outboard location spaced laterally from the boom heel to an inboard location ahead of the boom heel, comprising adjusting the lengths of the respective topping lifts to position the boom head above the cargo, the outboard topping lift being shorter than the inboard topping lift, lengthening the cargo fall to the level of the cargo, securing the cargo to the cargo fall, shortening the cargo fall to raise the cargo toward the boom head, then lengthening the outboard topping lift to about the length of the inboard topping lift, while maintaining the inboard topping lift at essentially constant length, and thereby swinging and lowering the boom head to position the cargo over the inboard location ahead of the boom heel, and releasing the cargo.

References Cited in the file of this patent UNITED STATES PATENTS 2,944,680 Banks July 12, 1960 FOREIGN PATENTS 72,787 Norway Nov. 3, 1947

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