GB2177374A

GB2177374A - Crane for application on offshore drilling platforms and the like

Info

Publication number: GB2177374A
Application number: GB08614343A
Authority: GB
Inventors: Jan Jacob Fleumer
Original assignee: KENZ KRAANTECHNIEK BV
Current assignee: KENZ KRAANTECHNIEK BV
Priority date: 1985-06-13
Filing date: 1986-06-12
Publication date: 1987-01-21
Also published as: NL8501703A; NL184414C; NL184414B; GB8614343D0; GB2177374B

Abstract

A crane for application on offshore drilling platforms and the like, which crane is supported on a carriage (10) and may be slewed thereon by means of a bearing, characterized in that the bearing is formed by a pivot member (11) mounted underneath the crane and protruding downwardly therefrom, and which pivot member (11) is supported in the carriage (10) on its upper side by a radial slide bearing (12) and on its lower side by a combination of a radial slide bearing (13) and a pivot bearing (14). <IMAGE>

Description

SPECIFICATION Crane for application on offshore drilling platforms and the like The present invention relates to a crane for application on offshore drilling platforms and the like, which crane is supported by means of a bearing on a carriage and may be slewed, viz. rotated horizontally about a vertical pivot, with respect thereto. Such a crane is generally known and mainly used for unloading supply ships.

In connection with the working conditions on drilling platforms, onto which helicopters regularly have to land to bring in or take off manpower and material, the total height of a crane as utilised on a drilling platform is limited.

On account of such limitation, a bearing of the crane on the co-operating carriage is applied, and which bearing is formed by a rotation ball path or a rotation roller path. previously, such bearings were applied in those movable cranes mounted onto motor vehicles.

However, the circumstances under which offshore cranes have to operate are completely different from those of motor vehicles having movable cranes mounted thereon. For example, ships have to be unloaded by the offshore cranes, which ships, especially in rough weather, may make strong movements with respect to the fixedly located drilling platform. As a consequence of these particular working conditions, it has been found necessary to regularly check the bearings of the offshore cranes on the co-operating carriages.

To carry out such a check of the bearings of an offshore crane, it is necessary to completely lift the crane, dismantle its rotation path, to remove the balls or rollers out of the rotation paths and to inspect the running surfaces in these rotation paths. Such a check requires substantial time and is therefore very costly.

It is an object of the present invention to overcome the problem of the difficult check up required of the known bearings of known offshore cranes.

According to the present invention there is provided a crane for application on offshore drilling platforms and the like, which crane is supported on a carriage and may be slewed thereon by means of a bearing, in which the bearing is formed by a pivot member mounted underneath the crane and protruding downwardly therefrom, which pivot member is supported in the carriage on its upper side by a radial slide bearing and on its lower side by a combination of a radial slide bearing and a pivot bearing.

The pivot member may be formed in various manners.

In a suitable embodiment of the invention, the pivot member is constructed in a funnelshaped manner upwardly from the bottom, so that the diameter of the upper radial slide bearing is larger than the diameter of the lower radial slide bearing.

Preferably, in an embodiment of the invention, the diameter of the upper radial slide bearing is two to four times larger than the diameter of the lower slide bearing.

In a particularly suitable embodiment of the invention, the pivot member is slidably mounted in an axial direction along the combination of radial- and step bearing enclosed in the carriage, such, that the pivot member may be pushed upwards with respect to the carriage and so that the cylinder-shaped sliding surface of the upper radial sliding bearing, present on the pivot member, may be slid out of the co-operating, also cylinder-shaped, sliding surface, present on the carriage.

The combination of the lower radial slide bearing and the step or pivot slide bearing may be simply obtained fron the market and require no maintenance, so that for the check up of the bearing only the sliding surfaces of the upper radial slide bearing are to be inspected. This may be simply carried out by simply pressing the pivot member in the carriage upwardly by which the sliding surface of the upper radial bearing becomes visible and so may be inspected.

The sliding surface of the upper radial slide bearing may be manufactured from various materials. In an embodiment of the invention, the sliding surface present on the pivot member consists of a plastics material, particularly Teflon.

Pushing the pivot member in the carriage upwardly may be carried out in various ways.

In a preferred embodiment of the invention, the pivot member may be pushed upwardly by means of a hydraulic cylinder to enable a check of one or both sliding surfaces of the upper slide bearing to be made.

In a suitable embodiment of the invention, the pivot member is supported in its pushed up position in a radial direction by means of the co-operating sliding surfaces of the upper radial slide bearing portions of the pivot member and the carriage.

The invention will be further illustrated, by way of example, with reference to the accompanying drawings in which: Fig. 1 is a side view of a crane according to the invention, as applied on offshore drilling platforms; Fig. 2 is a view of the bearing of the crane according to Fig. 1 on the carriage, and in which this bearing is in its operative position; and Fig. 3 is a view of the bearing according to Fig. 2 in which the bearing is in its pushed up check position.

As is shown in Fig. 1, the crane is formed by a jib or boom, consisting of a base section 1, a middle section 2 and a top section 3, and is upwardly and downwardly swingably supported in the main frame 4, which is supported by the base plate 5. By means of a boom hoist winch 6, a boom hoist wire rope 7 may be pulled in and by which an -A- frame B, as seen in the drawing, may be slewed counter clockwise and by which guyrope 9 will pull the boom upwards. The crane is supported via the base plate on the carriage 10.

As is shown in Fig. 2, the bearing, by means of which the base plate is supported on and in the carriage 10, is formed by a pivot member 11 mounted beneath the base plate, and which pivot member is constructed in a funnel-shaped manner from the bottom upwards, and by means of an upper radial slide bearing 12 and a combination of a lower radial slide bearing 13 together with a pivot slide bearing is supported in the carriage 10.

The radial slide bearing 13 and the pivot slide bearing 14 are readily available and require no maintenance.

As is shown in Fig. 2, the bearings 13 and 14 are locked in the axial direction in the carriage 10 and support the pivot member in the vertical direction.

The pivot member may be moved up in the bearings 12, 13, 14, as is shown in Fig. 5, and is effected by means of a hydraulic cylinder 15, which by means of bolts 16 is mounted to the carriage 10. By moving the piston 17 of the hydraulic cylinder 16 upwardly the pivct member 11 carrying the base plate 5 and the crane mounted thereon is moved upwards so that the sliding surface 18 of the synthetic material of the upper radial slide bearing has come above the co-operating sliding surface 19 of the carriage 10, so that in this position the sliding surface 18 may be inspected and, if necessary, bearing material may be replaced.

As is shown in Fig. 5, the pivot member in its pushed up position remains supported by the underlying combination of the radial/pivot slide bearing 13, 14 and by the support of the pivot member portion of the sliding surface against the sliding surface 19 of the carriage.

Claims

1. A crane for application on offshore drilling platforms and the like, which crane is supported on a carriage and may be slewed thereon by means of a bearing, in which the bearing is formed by a pivot member mounted underneath the crane and protruding downwardly therefrom, which pivot member is supported in the carriage on its upper side by a radial slide bearing and on its lower side by a combination of a radial slide bearing and a pivot bearing.

2. A crane as claimed in claim 1, in which the pivot member is constructed in a funnelshaped manner upwardly from the bottom, so that the diameter of the upper radial slide bearing is iarger than the diameter of the lower radial slide bearing.

3. A crane as claimed in claim 2, in which the diameter of the upper radial slide bearing is two to four times as large as the diameter of the lower radial slide bearing.

4. A crane as claimed in claim 1, 2 or 3, in which the pivot member is slidable in an axial direction along the combination of radial- and pivot slide bearings locked in the carriage, such that the pivot member may be pushed up with respect to the carriage and by which the cylindershaped sliding surface on the pivot member of the upper radial slide bearing is slid out of the co-operating, also cylindershaped, sliding surface on the carriage.

5. A crane as claimed in any preceding claim, in which the sliding surface on the pivot member of the upper radial slide bearing consists of synthetic plastics material.

6. A crane as claimed in any preceding claim, in which the pivot member may be pushed upwardly and out of the carriage by means of a hydraulic cylinder to enable a check and/or repiacement of one or both sliding surfaces of the upper slide bearing.

7. A crane as claimed in any preceding claim, in which the pivot member in its moved up position is supported in the radial direction on the carriage by means of the co-operating sliding surfaces of the upper radial slide bearing portions of the pivot member and the carriage.

8. A crane, substantially as hereinbefore described with reference to the accompanying drawings.