WO1999016696A1

WO1999016696A1 - Lifting apparatus

Info

Publication number: WO1999016696A1
Application number: PCT/NO1998/000286
Authority: WO
Inventors: Inge Dragsund
Original assignee: Odim Holding Asa
Priority date: 1997-10-01
Filing date: 1998-09-29
Publication date: 1999-04-08
Also published as: NO306900B3; NO306900B1; NO974532D0; NO974532L; AU9368298A

Abstract

A lifting apparatus for use on board a vessel, optionally when there is a sea, comprising a luffing boom (2) pivotally secured to a foundation (1) secured in the deck (5) of a vessel, where the luffing boom (2) is capable of pivoting between two extreme positions about a substantially horizontal tilting axis (3) close to one end of the luffing boom (2), wherein on the luffing boom (2), close to the end furthest from the tilting axis (3), there is provided a main boom (6) capable of rotation through 360° about an approximately horizontal axis relative to the luffing boom (2).

Description

Lifting apparatus

The present invention relates to a lifting apparatus, more specifically a lifting apparatus suitable for use on board a boat when there is a sea.

There is a great need for lifting apparatus at sea to transfer loads to the sea from a vessel, from the sea onto a vessel or between vessels. An apparatus frequently used is a so-called A-frame which comprises a generally A-shaped boom capable of being tilted back and forth relative to the vessel and where at the top there is provided a winch or a block over which a wire may run between the load and a winch.

However, when there is a sea a suspended load will act as a pendulum which might swing uncontrollably and move at considerable speed putting the vessel, the load and persons in the vicinity at risk. It is therefore an advantage to have a minimum pendulum length when handling such loads. With an A-frame as mentioned above, it will be possible to obtain a relatively short pendulum when the load is hauled up from the sea and the load is lowered down on board the vessel, that is to say when the A frame has been tilted into one of its extreme positions. However, in an intermediate position when the load is either taken on board or put out, the pendulum length will be considerable.

Thus, Norwegian Patent No. 161310 describes a method and apparatus for putting out and hoisting up a body at sea. The equipment in this case consists of a frame pivotally mounted in the deck of a vessel and which is capable of being swung out over the sea, and where outermost on the frame there is provided lifting tackle which can compensate for and counteract the motion of the vessel, thereby avoiding any jerking movements of the load resulting from the motion of the vessel. However, this is an apparatus having relatively small lifting height and which is adapted for the purpose of putting out and hoisting up in particular bodies of substantial inherent buoyancy, such as subsea vessels and the like. The apparatus is not suitable for handling general loads, and exhibits little flexibility.

GB 1 519 177 describes a crane having two arms: a lifting arm which allows a high lift, and an arm having its point of application close to the load to prevent sideways swinging. However, this is a large and complex apparatus which is not useful on board small vessels. Norwegian Patent No. 162227 describes a crane for use on board a vessel which is exposed to the motion of waves. This crane is equipped with a crane boom having means for compensating for wave motion in addition to a regulating and control device which automatically compensates for wave motion. A crane of this kind does not have the simplicity and functionality that it is sought to obtain with the present apparatus.

The object of the present apparatus is thus to provide a simple, reliable lifting apparatus which allows there to be a small distance between the lifting apparatus and the load, whilst permitting a considerable lifting height.

According to the present invention, this is achieved by a lifting apparatus for use on board a vessel, optionally when there is a sea, comprising a luffing boom pivotally secured to a foundation secured to the deck of the vessel, where the luffing boom is capable of pivoting between two extreme positions about a substantially horizontal axis close to one end of the luffing boom, wherein on the luffing boom, close to the end furthest from the tilting axis, there is provided a main boom capable of rotation about an approximately horizontal axis relative to the luffing boom.

In its broad features, the luffing boom of the present apparatus is similar to a conventional A-frame as mentioned above. To avoid the problem of a long pendulum for the suspended load, according to the present invention there is therefore provided on the apparatus a main boom capable of being rotated relative to the luffing boom. Thus, it is possible to ensure that the length of the pendulum is kept within an acceptable range in all positions of the luffing boom.

The present invention will now be described in more detail with reference to the attached figures, wherein:

Figure 1 is a side view of the present lifting apparatus in a first position;

Figure 2 is a side view of the present lifting apparatus in a second position;

Figure 3 is a side view of the present lifting apparatus in a third position;

Figure 4 is a bird's-eye view of the present lifting apparatus; and Figure 5 shows the present lifting apparatus seen in a plane perpendicular to Fig.

2.

Figure 1 is a side view of the present lifting apparatus mounted on the afterdeck at the trawl door on a trawler. For the sake of simplicity, the boat is indicated in broken lines, whilst the lifting apparatus has been drawn in solid lines.

The present lifting apparatus is divided into two main parts, a luffing boom (2) and a main boom (6), which are pivotally secured to one another and are capable of being rotated with the aid of a slewing ring (7). The luffing boom (2) is pivotal about a tilting axis (3) secured to the deck in a foundation (1). The luffing boom (2) is capable of being tilted back and forth relative to the deck (5) with the aid of one or more hydraulic cylinders (4) which are secured to the luffing boom at one of their ends and the deck (5) at their other end. In the illustrated embodiment the luffing boom can be tilted 45° forwards and 75° backwards or 120° altogether.

The main boom (6) is capable of being rotated 360° relative to the luffing boom (2) in a plane substantially perpendicular to the tilting axis (3). The slewing ring (7) is preferably a conventional, hydraulically operated slewing ring, but may of course also be powered electrically. Close to its free end, the main boom (6) has a swivel boom (8) mounted thereon which is substantially perpendicular to the main boom (6) and which lies substantially horizontally. On the swivel boom (8), which preferably is pivotally mounted in the main boom (6), there is secured one or more blocks (9) over which a wire (10) for lifting loads can run from a non-illustrated winch.

In Figure 1 the lifting apparatus is in a first position for hoisting a load on board. The luffing boom (2) has been tilted into a first extreme position, so that the slewing ring (7) is as low and as far aft as possible. In this way, the main boom (6) may be swung into a position which provides the best compromise between a low lifting point and a sufficient distance between ship and load. The load is hauled up by the wire (10) over block (9) to a non-illustrated winch further forward on the vessel.

As shown in the figure, the present lifting apparatus allows good control over the load in that the lifting point, i.e., the distance between the surface of the water or the load and the block (9) is relative small.

Figure 2 shows the lifting apparatus in a second position, where the luffing boom (2) has been tilted forward and into the boat by a hydraulic cylinder (4). The main boom (6) has been swung down to ensure a lifting point that is as low as possible, and thereby also a pendulum of minimum length between load and block (9). In Figure 3 the luffing boom (2) is in the same position as in Figure 2, but the main boom (6) has been swung as far forward in the boat as possible with the aid of the slewing ring (7). As indicated by the position of the wire (10), the load has now come onto the deck, and the wire (10) hangs approximately vertically down from the block (9). Here the load is on the deck and can be handled with the aid of other means.

Figures 4 and 5 show the present lifting apparatus in a bird's-eye view and seen from astern looking in towards the boat deck respectively. In the illustrated embodiment, the luffing boom (2) pivots about two foundations (1) with the aid of two hydraulic cylinders (4). As shown in Figures 4 and 5, the lifting apparatus so situated as to allow the main boom (6) to be rotated through 360° without being obstructed by the ship structure. The swivel boom (8), which is mounted outermost on the main boom (6), has three points of attachment for blocks (9) in the illustrated embodiment. The swivel boom (8) is preferably pivotally mounted to the main boom (6) so that the blocks can assume the most favourable position in relation to gravity and drag on the wire (10).

For larger and heavier lifts, there may of course conceivably be two sets of luffing booms and main booms where the swivel boom (8) was secured to a main boom on each side. However, the illustrated embodiment is preferred, since it is sufficiently strong for most purposes and allows plenty of space for any additional lifting apparatus located on the same deck on the opposite side of the boat, where both lifting apparatus of different types can be operated independently of each other. With the aid of the present lifting apparatus, it is thus possible to obtain a good combination of the desired low lifting point when there is a sea, and at the same time a large working area for the lifting apparatus and a top lifting height sufficient for most purposes.

In the illustrated embodiment, a winch located some distance from the lifting apparatus is used to manoeuvre the wire secured to the load. If so desired, in particular when handling relatively light loads, it may be appropriate to provide a winch for handling the wire on the main boom.

To further enlarge the working area of the present lifting apparatus, the deck (5) on which the lifting apparatus and the wire-handling winch are mounted, may of course be a part of a rotating platform. The lifting apparatus would then be capable hoisting loads both on board and off the vessel, both from the stern and the side of the ship. However, this is not shown in any of the figures.

Claims

P a t e n t c l a i m s

1.

A lifting apparatus for use on board a vessel, optionally when there is a sea, comprising a luffing boom (2) pivotally secured to a foundation (1) secured in the deck (5) of a vessel, where the luffing boom (2) is capable of pivoting between two extreme positions about a substantially horizontal swivel axis (3) close to one end of the luffing boom (2), characterised in that on the luffing boom (2), close to the end furthest from the swivel axis (3), there is provided a main boom (6) capable of rotation through 360┬░ about an approximately horizontal axis relative to the luffing boom (2).

2.

A lifting apparatus according to claim 1, characterised in that the main boom (6) can be rotated about its rotational axis with the aid of a hydraulically or electrically operated slewing ring (7).

3.

A lifting apparatus according to claim 1 or 2, characterised in that close to the outer end of the main boom (6) there is provided a winch.

4.

A lifting apparatus according to claim 1 or 2, characterised in that close to the outer end of the main boom (6) there is provided one or more blocks (9) over which a wire (10) can run between load and winch.

5.

A lifting apparatus according to one or more of the preceding claims, characterised in that said one or more blocks (9) are secured to a swivel boom (8) which is pivotally secured to the main boom (6).