GB2183596A

GB2183596A - Spreading bar for use in lifting heavy loads

Info

Publication number: GB2183596A
Application number: GB08622349A
Authority: GB
Inventors: Franz Gantke; Hans-Ulrich Kortmann
Original assignee: Hoesch Stahl AG
Current assignee: Hoesch Stahl AG
Priority date: 1985-12-04
Filing date: 1986-09-17
Publication date: 1987-06-10
Also published as: NL8602321A; NO159920C; NO863268L; FR2590880B1; GB8622349D0; DE3542881C1; NO159920B; GB2183596B; FR2590880A1; NO863268D0

Abstract

The bar is used for spreading steel ropes which are attached to a crane hook above the bar and to a heavy load below. It consists of a centre section 11 of tubular, box-shaped or girder cross-section with two welded ends 13 of cast steel. The welded ends 13 have four rope guiding grooves 10 arranged coaxially with one another, their axis 15 intersecting the bar axis 14 at right angles, and in pairs, two on each side of a plate shaped base body 12 having an essentially rectangular cross-section and a welded end 13 adjacent the centre section 11 of the bar. Ropes 8 from the crane hook are looped around the inner grooves adjacent the base body, and ropes 9 attached to the load are looped around the outer grooves. <IMAGE>

Description

SPECIFICATION Spreading bar for use in lifting heavy loads The invention relates to spreading bars which may be used in lifting heavy loads, for example for spreading steel ropes attached to a crane hook above the bar and to a heavy load below. The purpose of such spreading bars in such use isto forcethe steel ropes so far apart, when lifting the heavy load, that the load is subjected to no pressure, or at the most only a low pressure, from the rope force.

Such spreading bars are know, for example in offshore technologywhere floating cranes lift, among otherthings, modules weighing 3,000tonnes and over.

The known spreading bars have a rigid centre section, which may be formed from tubes, box girders or I-section girders, and two ends which have hitherto been manufactured almost exclusively from welded steel plates. The use of cast steel ends has been proposed only more recently.

In the case of the previously-known designs, which have either holes for fining shackles or rope guide grooves, additional bending stresses in the spreading bar may result from the introduction of eccentric forces. Furthermore, these spreading bars are designed for, and may be used almost exclusively in, specific applications only.

The main object of the present invention is to improve known spreading bars so that the stressing of the spreading bar, and hence its weigh, is reduced and its range of application increased.

According to the invention there is provided a spreading bar comprising a centre section and two end portions each having at least for rope-guiding grooves which are coaxial with one another and in pairs at opposite sides ofthe centre line ofthe bar, the groove intersecting the bar axis substantially at right angles.

In use of a bar according to the invention, it is advantageousforthe inner rope-guiding groovesto receive upwardly-directed double ropes.

Bars according to the invention, which are also economical in manufacture, can afford the following main advantages: a) In use, the direction of a double rope running obliquely upwards can be varied almost infinitely without any eccentricity occurring between the three lines of action of the upper double rope, the lower double rope and the spreading bar. This reduces to a minimum the loading moments on the spreading bar, thereby resulting in a considerable reduction in the weight of the whole system being possible.

b) On completion of any operation the spreading bar can be used in other applications since its usability is guaranteed under all angle situations occurring in practice.

Embodiments of the invention will now be described by way of example with reference to the drawings, in which: Figure lisa schematic perspective view of a previously-known spreading bar in use, Figure 2 is an end view of a spreading bar embodying the present invention, and Figure3is a plan viewofthe barof Figure 2.

Figure 1 shows a heavy load, a module 1, suspended from a crane hook 2, by means of four doubleropes3which areforcedapartbyspreading bars4 so that they make angles of 900 with the upper edges of the end walls of the module 1 orto planes parallel to the walls, thus being unableto exert any major compressive forces on the module 1.

In the case ofthe one end 5 of one ofthe spreading bars 4, the double ropes 3 are secured to lugs on the bar4bymeansofshackles6.

In the spreader bar embodying the invention and shown in Figues 2 and 3, cast steel ends 7, onlyone of which is shown, rre provided with rope-guiding grooves 10 for receivir.the double ropes 8A9. The ropes 8 are looped arnund"'r6pe-guiding grooves 10- and extend upwardly to a crane hook. The ropes 9 are looped around further grooves 10 and extend downwardly to the load, the four grooves 10 being mutually parallel. A plate-shaped, thick-walled base body 12 forms an extension of a centre bar section 11 which, in this case, is tubular.On each side ofthis body, at an adequate distance from a welded end 13 of the tubular bar section 11 are arranged two of the parallel rope-guiding grooves 10. All fourgrooves 10 have the same axis 15 which intersects the axis 14 of the bar at right angles.

When a load is applied by the heavy load 1 in use of two bars 4, a tensile force is generated in each ofthe four lower double ropes 9, which force runs through the point of intersection of the bar axis 14 with the axis 15 ofthe rope-guiding grooves. This tensile force is deflected by the spreading bar and generates a tensile force in the upper double ropes 8. These two tensile forces produce a compressive force in the spreading bar.

The upwardly-directed double ropes 8, which must absorb higher rope forces because oftheir oblique positions, are best arranged to run in the inner rope guiding grooves immediately adjacent to the base body 12. The downwardly-directed double ropes 9 will then run in the outer rope guiding grooves.

Although bending andtorsion moments are generated within the end of the spreading bar generally, for which both the solid base body 12 and the rope guiding elements 16 formed between the rope-guiding grooves 10 must be adequately dimensioned, the lines of action of the forces mentioned intersect without eccentricities at one point, thereby creating a state of equilibrium without external moments.

1. A spreading bar comprising a centre section and two end portions each having at least four rope-guiding grooves which are coaxial with one another and in pairs at opposite sides of the centre line of the bar, the groove axis intersecting the bar axis substantially at right angles.

2. Aspreading bar according to claim 1, in which thecentresection isoftubular,barorgirder cross-section.

3. Aspreading bar according to claim 1 or2, in

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Spreading bar for use in lifting heavy loads The invention relates to spreading bars which may be used in lifting heavy loads, for example for spreading steel ropes attached to a crane hook above the bar and to a heavy load below. The purpose of such spreading bars in such use isto forcethe steel ropes so far apart, when lifting the heavy load, that the load is subjected to no pressure, or at the most only a low pressure, from the rope force. Such spreading bars are know, for example in offshore technologywhere floating cranes lift, among otherthings, modules weighing 3,000tonnes and over. The known spreading bars have a rigid centre section, which may be formed from tubes, box girders or I-section girders, and two ends which have hitherto been manufactured almost exclusively from welded steel plates. The use of cast steel ends has been proposed only more recently. In the case of the previously-known designs, which have either holes for fining shackles or rope guide grooves, additional bending stresses in the spreading bar may result from the introduction of eccentric forces. Furthermore, these spreading bars are designed for, and may be used almost exclusively in, specific applications only. The main object of the present invention is to improve known spreading bars so that the stressing of the spreading bar, and hence its weigh, is reduced and its range of application increased. According to the invention there is provided a spreading bar comprising a centre section and two end portions each having at least for rope-guiding grooves which are coaxial with one another and in pairs at opposite sides ofthe centre line ofthe bar, the groove intersecting the bar axis substantially at right angles. In use of a bar according to the invention, it is advantageousforthe inner rope-guiding groovesto receive upwardly-directed double ropes. Bars according to the invention, which are also economical in manufacture, can afford the following main advantages: a) In use, the direction of a double rope running obliquely upwards can be varied almost infinitely without any eccentricity occurring between the three lines of action of the upper double rope, the lower double rope and the spreading bar. This reduces to a minimum the loading moments on the spreading bar, thereby resulting in a considerable reduction in the weight of the whole system being possible. b) On completion of any operation the spreading bar can be used in other applications since its usability is guaranteed under all angle situations occurring in practice. Embodiments of the invention will now be described by way of example with reference to the drawings, in which: Figure lisa schematic perspective view of a previously-known spreading bar in use, Figure 2 is an end view of a spreading bar embodying the present invention, and Figure3is a plan viewofthe barof Figure 2. Figure 1 shows a heavy load, a module 1, suspended from a crane hook 2, by means of four doubleropes3which areforcedapartbyspreading bars4 so that they make angles of 900 with the upper edges of the end walls of the module 1 orto planes parallel to the walls, thus being unableto exert any major compressive forces on the module 1. In the case ofthe one end 5 of one ofthe spreading bars 4, the double ropes 3 are secured to lugs on the bar4bymeansofshackles6. In the spreader bar embodying the invention and shown in Figues 2 and 3, cast steel ends 7, onlyone of which is shown, rre provided with rope-guiding grooves 10 for receivir.the double ropes 8A9. The ropes 8 are looped arnund"'r6pe-guiding grooves 10- and extend upwardly to a crane hook. The ropes 9 are looped around further grooves 10 and extend downwardly to the load, the four grooves 10 being mutually parallel. A plate-shaped, thick-walled base body 12 forms an extension of a centre bar section 11 which, in this case, is tubular.On each side ofthis body, at an adequate distance from a welded end 13 of the tubular bar section 11 are arranged two of the parallel rope-guiding grooves 10. All fourgrooves 10 have the same axis 15 which intersects the axis 14 of the bar at right angles. When a load is applied by the heavy load 1 in use of two bars 4, a tensile force is generated in each ofthe four lower double ropes 9, which force runs through the point of intersection of the bar axis 14 with the axis 15 ofthe rope-guiding grooves. This tensile force is deflected by the spreading bar and generates a tensile force in the upper double ropes 8. These two tensile forces produce a compressive force in the spreading bar. The upwardly-directed double ropes 8, which must absorb higher rope forces because oftheir oblique positions, are best arranged to run in the inner rope guiding grooves immediately adjacent to the base body 12. The downwardly-directed double ropes 9 will then run in the outer rope guiding grooves. Although bending andtorsion moments are generated within the end of the spreading bar generally, for which both the solid base body 12 and the rope guiding elements 16 formed between the rope-guiding grooves 10 must be adequately dimensioned, the lines of action of the forces mentioned intersect without eccentricities at one point, thereby creating a state of equilibrium without external moments. CLAIMS

3. Aspreading bar according to claim 1 or2, in which the groove pairs of each end portion are separated buy a plate portion which lies in a plane substantially perpendicularto the groove axis and extends to the centre section of the bar.

4. A spreading bar according to claim 3, in which the plate portion is welded to the centre section.

5. Aspreading barsubstantiallyas hereinbefore described with reference to Figures 2 and 3 ofthe drawings.

6. A lifting assembly comprising a spreading bar according to any preceding claim, the inner rope guiding grooves at each bar end receiving respective upwardly-directed ropes and the outer grooves at each bar end receiving respective downwardly-directed ropes.