Hoisting assembly
AssigneeHeerema Marine Contractors Nederland B.V.
InventorWouter Johannes Slob
Life of this patent
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Abstract
A hoisting assembly for lifting or lowering a heavy object includes an upper fixed block, an upper movable block being suspended from the upper fixed block by at least one first rope which is reeved into one or more first rope lengths between the upper fixed block and the upper movable block, a lower movable block being connected to the upper movable block by at least one second rope which is reeved into one or more second rope lengths between the upper fixed block and the upper movable block. The first and second ropes are reeved in such a way that in use the upper movable block can be positioned at a distance greater than zero from the upper fixed block and at a distance greater than zero from the lower movable block by controlling the lengths of the first and second ropes.
Claims16
A hoisting assembly for lifting or lowering an object, the hoisting assembly comprising:
- an upper fixed block;
- an upper movable block being suspended from the upper fixed block by at least one first rope which is reeved in one or more first rope lengths between the upper fixed block and the upper movable block;
- a lower movable block being connected to the upper movable block by at least one second rope which is reeved in one or more second rope lengths between the lower movable block and the upper movable block, wherein the first and second ropes are reeved in such a way that in use the upper movable block can be positioned at a distance greater than zero from the upper fixed block and at a distance greater than zero from the lower movable block by controlling the lengths of the first and/or second ropes;
- the hoisting assembly comprising a data processing unit configured to receive:
- excitation data relating to external excitations on the hoisting assembly and
- hoisting assembly data relating to the response characteristics of the hoisting assembly to external excitations;
- wherein the data processing unit is configured to determine a favourable position of the upper movable block between the fixed block and lower movable block on the basis of the excitation data and the hoisting assembly data, which favourable position results in a limited response of the hoisting assembly to a range of external excitations.
A method of lifting or lowering a heavy object, the method comprising:
- providing a hoisting assembly comprising:
- an upper fixed block;
- an upper movable block being suspended from the upper fixed block by at least one first rope which is reeved in one or more first rope lengths between the upper fixed block and the upper movable block;
- and
- a lower movable block being connected to the upper movable block by at least one second rope which is reeved in one or more second rope lengths between the lower movable block and the upper movable block, wherein the first and second ropes are reeved in such a way that in use the upper movable block can be positioned at a distance greater than zero from the upper fixed block and at a distance greater than zero from the lower movable block by controlling the lengths of the first and second ropes;
- positioning the upper movable block at a predetermined position between the upper fixed block and the lower movable block;
- and
- controlling a spring coefficient of the total hoisting assembly between the upper fixed block and the lower movable block by controlling the position of the upper movable block between the upper fixed block and the lower movable block to control the natural frequency of the total system in such a way that the response of the system to a range of frequencies of excitation is reduced.
Dependencies are inferred from the claim text.