US3090493A - Preventer system for derricks on ships - Google Patents

Description

muy! mn" M lllkullllllllllll /N VE N TOR Chr/ls//bn Landman by im @zu @1 @M A T TORNE YS May 21, 1963 C. LANDTMAN 3,090,493

PREVENTER SYSTEM FOR DERRICKS ON SHIPS F'iled 0G11. 26, 1960 5 Sheets-Sheet 2 slsf /N VEN TOR Christ/bn Landfman May 21, 1963 c. LANDTMAN 3,090,493

PREVENTER SYSTEM FOR DERRICKS ON SHIPS Filed 0G12. 26. 1960 5 Sheets-Sheet 3 Chr/brian Landfman by ma@ (Mwwg ATTORNEYS cccc NpTMAN 3,090,493 SYSTEM FOR DERRICKS oN s IPs May 21, 1963 c. LANDTMAN PREVENTER SYSTEM FOR DERRICKS oN SHIPS 5 Sheets-Sheet 5 Filed 001'.. 26. 1960 INVENTOR by mmf/7%@ PUQ/fw@ Afin/'nays 3,090,493 IIREVENTER SYSTEM FOR DERRICKS N SHIPS Christian Landtman, Helsinki, Finland, assigner to Wrtsil-yhtyrn @y-Wrtsil-koncernen Ab, Helsinki,

Finland Filed (Bet. 26, 19nd, Ser. No. 65,155 Claims priority, application Finland Oct. 2,7, 1959 4 Claims. (Cl. 212-3) The present invention relates to an improved preventer system Vfor loading booms or derricks pivotally connected to a vertical loading mast yor a corresponding pole on ships and being topable by .the aid of a winch operated topping Wire fand slewable sidewise by means of two guys. Known booms are arranged according to two main principles, ie. either movable or coupled. ln a movable system the booms are moved during their work as well in vertical as in horizontal direction and are often used single. In a coupled system the booms are unmoved during their operation and used pairwise, whereby two booms are mutually cooperating and arranged .beside each other. At coupled booms is Ias a rule one boom placed over the `cargo -hold of the ship and the other `one projecting sidewise from the ship over the quay. The lifting wire of coupled booms are attached to a mutual cargo hook, by which the lifting Wires are cooperating at the handling of the cargo.

The present invention refers especially to a preventer system for coupled booms.

When the cargo is handled by coupled, uninovable booms and the lifting wires of the both booms act upon the cargo, horizontal force components will arise in the lifting wires and cause tensions in the outer guys of each boom. In order to strengthen said outer guys one uses extra ropes or so called preventers. When the slanting position of the booms is to be adjusted the guys and the preventers in earlier known system must be loosened before the top wire may be operated by the topping winch. It is especially frequently necessary to adjust the slanting position of the boom over the cargo hold of the ship in order to reach the different points within the cargo hold. On account yof the fact that said boom cannot be topped without an earlier loosening of the guys and preventers 'this means that the loading work must be interrupted which represents 'a severe drawback.

It is an object of the present invention to eliminate said disadvantage and make the displacement of the boom over the cargo bold possible by means of the topping winch without being forced earlier to adjust the preventer and the guy that is without being forced to interrupt the loading work. By such an improvement `a more eilicient use of the topping winch will also be obtained.

The preventer system according to the invention comprises one preventer and one guy for each adjustable boom. rlhe system is 'mainly characterized thereby that the guy is attached between the boom top and a guy point in such a way as to gui-de the boom top yduring the topping oper-ation along a circular path in a plane between the boom and the preventer, for instance parallel tothe center line of the ship, `and that the preventer, in respect .of the guy is arranged yon the opposite side .of said moving plane of the boom top, whereby the preventer is arranged like -two branches running from two separate preventer points to the boom top so that during topping of the boom the one preventer branch will be shortened land the other correspondingly lengthened. Hereby the preventer tries to guide the boom top along an elliptical path. Hereby the boom will get a continuous support in both side directions during Iits topping movement and neither guy nor preventer will have to be loosened or altered before the displacement of the topped boom.

The invention will be explained more in detail in the Haired tates @arent @if 3,@99-,493 Patented May 2l, 1963 2 following referring to the accompanying drawings, in which:

FIG. l illustrates coupled booms with a known preventer system,

FIG. 2 illustrates an improved preventer system according to the invention. Since this system is intended for that boom which is 'arranged over the cargo bold, the other boom projecting over the quay fixed by ordinary guys yis not shown in this figure.

FIG. 3 illustrates a diagrammatic View of the system of FIG. 2 and more particularly the attachment points of the preventer and the guy in the system of coordinates.

FIGURE 4 is a diagrammatic view of a modification, and

FIGURE 5 isa similar diagrammatic View of a further modification.

In the various gures of the drawing the elements corresponding to one another are indicated by the same reference numerals.

The boom over the cargo hold is indicated by 12 while the other one of the coupled bloom pair, projecting side- -wise from the ship side over the quay, see FIG. 1, is indicated by 13. The boom 12 is privotally connected near 14 to the loading mast 1S and the boom 13 in a corresponding way iixed near 16 to the loading mast 17.

The boom 12 is kept in a slanting position respectively topp-ed by fa topping wire 3 manoeuvered by a topping Winch 4. The other 'boom has a corresponding topping wire 18 'and a winch 19. The sidewise adjustment and fixing of the booms are eifectuated by guys and preventers. rIhe preventer of the boom 12 in FIG. l is indicated by 1 and its guys by 2 and 101. The preventer of the boom 13, FIG. l, is indicated by 8` tand its yguys by 9 and 11. The cargo 22 is lifted by the wire 23 of the boom 12 and the wire 24 of the boom 13 operated by the winch drums 20 and 21 respectively.

According to the `earlier known preventer system illustrated in FIG. 1 both booms are primarily adjusted into a certain wanted position and fixed there by the guys and the preventers. It is not possible to alter the positions of these booms without an earlier loosening ofthe preventers and the guys. If one wishes to top the boom 12 in order to reach another point inside the cargo hold one. must interrupt the loading work, then loosen and adjust the preventer and the guys, then alter the slanting position of the boom 12 by aid of the topping wire 3 and its topping winch 4 and then again x the preventer andthe guys before the loading can be continued over a new point of the cargo hold.

This tiresome necessity is avoided by the system according to the invention and illustrated in FIG. 2 and indicated in FIG. 3.

According to FIG. 2 the system comprises one preventer 6, 7 and one guy 5*. In this embodiment the right side of the boom 12 is supported by the guy 5 ixed partly near the top P of the boom 12 and partly at the point C near the ship deck. The opposite side of the `hoorn v12is supported by the preventer the one end of which being lixed at a point A on a transversal support 26 of the loading mast 15 and the other end in a point B near the ship deck. The preventer is drawn'over a block 25 near the boom top P, which divides the preventer into two parts 6 and 7. The lower end of the boom 12v being pivotally connected to the loading mast 1S is indicated by D.

The guy 5 is arranged into such a position that when the boom 12 is topped in vertical direction by aid of the topping wire 3 and the topping winch 4, the top P of the boom will move in a geometrical plane approximately parallel to the longitudinal symmetric lane. of the ship. It is hereby to observe that the guy 5 needs not to be loosened, displaced or changed during said topping movement of the boom. Neither needs the preventer to be altered since when changing the position of the boom as mentioned above the one part of the preventer, for instance 6, will be shortened and the other part, for instance 7, correspondingly lengthened running through the block 25.

The fastening points A and B of the preventer in FIG. 2 according to a preferred embodiment of the invention are determined by a certain equation. Hereby attention is paid to the fact that while the boom topy P, due to its attachment to the guy 5, will move along a circular path in a plane, the block 25 governed by the preventer 6, 7 will try to guide the boom top along an elliptical path. Consequently the points A and B must be choosen in a way which gives the best possible coincidence between said elliptical and said circular paths. The equation as aforementioned is the following:

in which c, b, e and d, b, frepresent the x, yand z-coordinates for the fastening points respectively in a system of cordinates, where the x-'y-plane substantially is the lsame in which the top of the boom is moving and the z-axis of which approximately corresponds with the straight line through the fastening point C for the guy and the pivot 14 of the boom 12, i.e. the point D. The boom and the guy S fastened at the top of the boom move each along the surface of a cone whereby `their common bases and axes approximately will coincide with said x-y-plane and zaxis respectively of the system of coordinates. The direction of the y-aXis coincides with the projection of the boom on the plane of coordinates, when the boom is in a central position. The length of the projection of the boom on the plane of coordinates is indicated by R. The above mentioned equation is based upon the factthat the position of the common point of both portions 6, 7 of the divided preventer is defined by that ellipse in the x--yplane which as far as possible connects to the arc of a circle formed by the top of the boom.A

By means of this system it is possible with a coupled pair of booms to raise and lower the boom positioned above the loading hold without being forced to adjust the preventer and the guy and nevertheless achieve a Sudicient support in horizontal direction. When loading and unloading with coupled booms the load acting upon the preventers indicated by 1 and 8 in FIG. l is very big as mentioned above. The inner guys indicated lby 2 and 9 in FIG. l are only slightly loaded. I'herefore a known arrangement of the preventer, which can also be mathematically vderived from the present invention, if taking the special case where both the fastening points of the preventer coincide on the z-axis is often unpractical, because the preventer points for obtaining acceptable angles and forces would have to be displaced outside the ship.

The same principle as above explained may also be adapted in such a Way that theblock at the top of the boom is substituted by blocks at the two fastening points of the divided preventer whereby the preventer ends are xed at the boom top. Hereby the preventer parts running through the blocks at the preventer points may lead to a `special winch drum and operated bythis in such a way that when the one preventer part is wound up on the drum the other is unwound. By this arrangement it is possible to operate the topping of the boom by the aid of the preventer. Consequently the conventional topping wire and topping winch can be eliminated.

According to another embodiment the preventer is running from the boom top through the block at the lirst :preventer point directly to the other preventer point block and `back to the iboom. top Wlhere 4it is fixed. This arrangement does not eliminate the topping winch.r

The above modiiicatons are described below.

According to 'the arrangement of FIGUREA the preventer is fastened at the top P of the boom y12. Starting from this fixing point it runs as shown at 6 over a block at the point A at the end of `the transversal support 26 of the loading mast l5. From the block at A it continues over a second block at A', la third block at B and returns as shown iby 7 to the lfixing point P at the boom. top. The preventer thus forms -a closed loop which moves over said three blocks when the boom is lifted or lowered.

According to FEGURE 5 there is also three blocks at respectively A, A and B. In addition, a winch drum 27 is arranged, :for example, on the loading `rnast 15. The preventer lines are fixed at P on `.the top- `of fthe boom 12. The one lbranch l6 of the preventer line runs over the block at A and is Wound up on said winch drum 27. The other preventer branch 7 is drawn over fthe iblocks at B and A and is lalso wound up on said winch drum 27 Ibut in an opposite direction as to the ,branch 6 in such a 'way that when the boom is topped, i.e. lifted or lowered, the winch drum is rotated correspondingly whereby the one preventer `line br'aneh is Wound up and the other one is unwound from the Winch drum, whereby the supporting function of the preventer onthe boom is maintained un changed. It should lbe observed that the arrangement shown in FIG. 5 makes :it possible to `operate the topping of the boom by the aid of the winch drum 27. 'llhe conventional winch drum 2()A does not need to be used at al1 and can consequently be eliminated.

What I claim is:

1. A pneventer system for ship booms pivotally conneoted to a vertical pole such as ia loading mast, said preventer system comprising supporting ropes arranged on `both .sides of Ithe plane in which the hoorn top moves when topped, characterized thereby that it has one guy fixed `between the Ihoorn top land la guy point situated on the line runnin-g :from the pivot of the boom perpendioularly against said moving plane of the boom top and one preventer attached to the boom top and running therefrom as Iseparate :branches to two preventer points on the same side of the movement plane of the boom top, whereby the preventer is attached in such a way to ,the boom top :and to said two preventer points that, when topping the boom, the one preventer branch is shortened and the other correspondingly iengthene-d so as to make the displacement of the boom possible fwithout loosening or altering the preventer and the guy.

2. .A pre-Venter system as explained in claim 1, characterized thereby that the preventer points are defined by the formula:

'in rwhich c, b, e respectively d, b, f are the coordinates in .a system the x-yplane of which coincides substantially with the plane which the boom ltop moves and the zaaxis substantially coincides Wit-h the line connecting the pivot of the boom with the guy point of the guy, and R being the length of the projection of the boom on the plane of the coordinates x and y.

3. A preventer system yaccording to claim l, in which the preventer 'is arranged to runas a continuous loop starting from a fixing point at the boom top and through blocks at the two preventer points on the same side of -the moving plane of the rboom top.

4. A preventer system according to claim 3, characterized thereby that the preventer ends led through the pre- D Venter point blocks are connected to a winch drinn in such a way that the one preventer part is unwound simultaneously as the other part is wound up.

References Cited in the le of this patent UNITED STATES PATENTS 2,782,938 Mege Feb. 26, i1957 FOREIGN PATENTS 354,235 Great Britain Aug. 5, 1931

Claims (1)

1. A PREVENTER SYSTEM FOR SHIP BOOMS PIVOTALLY CONNECTED TO A VERTICAL POLE SUCH AS A LOADING MAST, SAID PREVENTER SYSTEM COMPRISING SUPPORTING ROPES ARRANGED ON BOTH SIDES OF THE PLANE IN WHICH THE BOOM TOP MOVES WHEN TOPPED, CHARACTERIZED THEREBY THAT IT HAS ONE GUY FIXED BETWEEN THE BOOM TOP AND A GUY POINT SITUATED ON THE LINE RUNNING FROM THE PIVOT OF THE BOOM PERPENDICULARLY AGAINST SAID MOVING PLANE OF THE BOOM TOP AND ONE PREVENTER ATTACHED TO THE BOOM TOP AND RUNNING THEREFROM AS SEPARATE BRANCHES TO TWO PREVENTER POINTS ON THE SAME SIDE OF THE MOVEMENT PLANE OF THE BOOM TOP, WHEREBY THE PREVENTER IS ATTACHED IN SUCH A WAY TO THE BOOM TOP AND TO SAID TWO PREVENTER POINTS THAT, WHEN TOPPING THE BOOM, THE ONE PREVENTER BRANCH IS SHORTENED AND THE OTHER CORRESPONDINGLY LENGTHENED SO AS TO MAKE

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