GB2185459A

GB2185459A - Spreading bar for use in lifting heavy loads

Info

Publication number: GB2185459A
Application number: GB08628239A
Authority: GB
Inventors: Franz Gantke; Hans-Ulrich Kortmann
Original assignee: Hoesch Stahl AG
Current assignee: Hoesch Stahl AG
Priority date: 1986-01-17
Filing date: 1986-11-26
Publication date: 1987-07-22
Also published as: GB8628239D0; NO159921B; FR2593162B1; NO864217L; NO159921C; NL8602744A; GB2185459B; DE3601263C1; NO864217D0; FR2593162A1

Abstract

The bar 5 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 10 of tubular, box- shaped or girder cross-section to which are welded two ends 7 of cast steel. The ends 7 have rope guide grooves 8, 9, for reception of single or continuous ropes. The central planes 13, 15 of these grooves intersect along a straight line which intersects the axis 14 of the centre section 10 at right angles. The arrangement of the two rope guide grooves 8, 9 reduces the stresses in, and hence the weight of, the bar relative to previously-known bars. The upper rope guide 9 may increase in width towards its open end. <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 to a heavy load below. The purpose of such spreading bars in such use is to force the 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 known, for example in offshore technology where floating cranes lift, among other things, modules weighing 3,000 tonnes 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 fitting 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.

Although another proposed design effects significant improvements with regard to the application of forces, it is not suitable for use with single and continuous ropes because these would cause excessively high torsional stresses in the spreading bar.

However, the use of single and/or continuous ropes is increasing because this use avoids, among other things, damage to the ropes, e.g. deformation arising from the arrangement of several ropes on one hook.

The object of the present invention is to improve known spreading bars so that, even when using single and/or continuous ropes, the stressing of the spreading bar, and hence its weight, is reduced and its range of applications increased.

According to the invention there is provided a spreading bar comprising a central section and two end portions each having two rope guide grooves, the central planes of which intersect along a line which intersects the axis of the central section substantially perpendicularly.

Advantageously, at least one upper rope guide groove increases in width towards its open ends. This facilitates, in use of the bar, attainment of a variety of directional angles of the upper rope.

Bars according to the invention, which are also economically manufactured, can afford the following main advantages: a) In use, the direction of the single or continuous rope running obliquely upwards can be varied almost infinitely without any eccentricity occurring between the three lines of action of the upper rope, the lower 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 pos- sible.

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.

An embodiment of the invention will now be described by way of example with reference to the drawings, in which: Figure 1 is a schematic perspective view of a previously-known spreading bar in use, Figure 2 is a side view of one end of a spreading bar embodying the present invention, and Figure 3 is an end view of the bar of Fig. 2.

Fig. 1 shows a heavy load, a module 1, suspended from a crane hook 2 by means of single ropes 3 and 4 which are forced apart by spreading bars 5 so that they make angles of 90 with the upper edges of the end walls of the module 1, or to planes parallel to the walls, thus being unable to exert any major compressive forces on the module 1.

In this previously-known arrangement the rope forces are deflected by means of guide grooves between two fishplates 6 which extend in planes perpendicular to the axis of the spreading bars 50. A moment-free application of forces is possible only in special cases.

In the spreading bar embodying the invention and shown in Figs. 2 and 3, cast steel ends 7 (only one of which is shown) are provided with rope guide grooves 8, 9 for receiving a single or continuous ropes 3, 4 which are directed downwardly and obliquely upwardly respectively. A solid base body 11 with a welded end 12 forms an extension of the centre bar section 10 which, in this case, is tubular. On the end of this body facing away from the centre section 10, there is the integrally cast lower rope guide groove 8, with its central plane 13 perpendicular to the axis 14 of the bar, and, above it, the upper rope guide groove 9 which is also integrally cast and has a central plane 15 which intersects the central plane 13 of the lower rope guide groove 8 on a line through which the axis 14 of the spreading bar 5 passes. Widening of the upper rope guide groove 9 towards the top on the bar permits an angular deflection of the rope 4 of about +15".

When the weight of the module 1 is applied to the spreading bar 5, a tensile force is generated in each of the four lower ropes 3. This force acts through the point of intersection of the axis 14 of the spreading bar 5 with the line of intersection of the central planes 13, 15 of the rope guide grooves 8, 9 and is deflected by the spreading bar to generate a tensile force in the upper rope 4. A compressive force in the spreading bar is thus produced.

Claims

1. A spreading bar comprising a central section and two end portions each having two rope guide grooves, the central planes of which intersect along a line which intersects the axis of the central section substantially perpendicularly.

2. A spreading bar according to claim 1, in which the central section is of tubular, box or girder cross-section.

3. A spreader bar according to claim 1 or 2, in which the end portions are welded to the central section.

4. A spreading bar according to any preceding claim, in which at least one upper rope guide groove increases in width towards its own ends.

5. A spreading bar substantially as hereinbefore described with reference to Figs. 2 and 3 of the drawings.