Traversing hoists – Having means facilitating assembly or disassembly
Patent
1986-03-14
1987-06-16
Peters, Jr., Joseph F.
Traversing hoists
Having means facilitating assembly or disassembly
212192, 212239, 212262, B66C 2326
Patent
active
046730931
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for mooring a crane for heavy loads, in particular an offshore crane, provided with a crane jib which is hingedly connected to a slewing frame and by means of luffing wires can be luffed in and out, while to increase the maximum permissible load some of the luffing wires are extended by means of mooring wires which are fixed some distance away from the crane.
Cranes with such a "tie-back" system, which extends some of the luffing wires, are known and are used to permit an increase of the maximum permissible load. Both the foundation of the crane and the luffing wires are better loaded through use of the triangle of forces formed. For example, a 2000 ton crane is made suitable for a load of 3000 tons. It is important for the guy wires to be fastened a good distance away from the crane, for example on the deck of the crane pontoon. The further away this fastening point is from the crane, the greater the radius of action of the crane jib can be and the more the load on the crane jib is reduced. In general, the distance between the fastening point of the guy wires and the crane is limited, which means that the advantage of the greater radius and the higher permissible crane load is subject to limitations, for the extended luffing wires must always remain above the non-extended luffing wires in order to produce the above-mentioned advantages.
The object of the invention is, starting from the crane mentioned in the preamble, in the case of which there is a certain distance between the fixed fastening point of the guy wires and the crane, to increase even more the maximum permissible crane load and the radius of action of the crane jib.
According to the invention, the process is to this end characterised in that provision is made in the assembly of interconnected guy wires and luffing wires, by means of a guy mast, for a kink facing away from the crane.
As a result of said kink, there will be a greater angle between the extended luffing wires and the luffing wires which are not extended. It is this greater angle which leads to the advantage of the greater radius of action and a reduction of the load of the crane jib.
The guy mast is preferably disposed so that with one end it hinges on the top of the frame and with its other end forms a connection between the guy and luffing wires.
According to the invention, the crane jib is maintained in the fully luffed-in position, and one or more guy wires are provided between a fixed point at a distance from the crane and the free end of a guy mast hingedly connected with the top of the frame, while some of the luffing hoisting blocks at the top end of the frame are detached from the frame and moved towards the free end of the guy mast and attached to that end, and the guy mast is pivoted into the working position through tightening of the luffing wires connected with said mast, and finally, the crane jib is released for luffing out.
For maintaining the crane jib in the fully luffed-in position, use is preferably made of a temporary connection between crane jib and frame, this connection being removed at the end of the luffing procedure.
In order to guide the movable luffing hoisting blocks during their movement towards the free end of the guy mast in such a way that they cannot strike parts of the crane, separate guide channels could be used. It is, however, cheaper if the guy mast serves as the guide for said blocks during the movement of these movable luffing hoisting blocks.
The invention will now be explained further with reference to the schematic figures.
FIGS. 1 to 4 show views of the crane in the various stages which are necessary to practice the special mooring process according to the invention, with the lines drawn in FIG. 4 indicating the end stage.
FIG. 5 shows a view of the top side of the crane frame of the crane for practicing the invention, on a larger scale.
The offshore crane shown in the figures comprises a pontoon 1, a support 2, an A-frame 3 slewably mounted on said support and a crane jib 4 which is hingedly connect
REFERENCES:
patent: 2609939 (1952-09-01), Davidson et al.
patent: 2738884 (1956-03-01), Callouette et al.
patent: 2883068 (1959-04-01), McIntyre
patent: 3664516 (1972-05-01), Goudy
patent: 3768664 (1973-10-01), Bauer et al.
patent: 3923163 (1975-12-01), Brewer
patent: 4297961 (1981-11-01), Johnson, Jr.
Avila Stephen P.
Gusto Engineering C.V.
Peters Jr. Joseph F.
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