APPARATUS AND A METHOD FOR USE IN HANDLING A LOAD

Abstract: Apparatus and a method for use in handling a load is described. The apparatus includes a load-bearing rope (1, 19), and a mechanism for paying out and recovering the rope (1, 19). There is also a drum (3, 12, 15, 16) for holding a service cable (2, 17) with a length of the service cable (2, 17) extending from the drum (3, 12, 15, 16). A wrapping device rotates the length of service cable (2, 17) around the rope (1, 19) as the rope (1, 19) is payed out to wrap the service cable (2, 17) around the rope (1, 19), and to unwrap the service cable (2, 17) from the rope (1, 19) as the rope is recovered.

Description: "Apparatus and a Method for Use in Handling a Load" This invention relates to apparatus for use in handling a load which is capable of raising and lowering, or of towing, a load and also handling service cables and/or hoses connected to the load. The invention is particularly, but not exclusively, applicable to the handling of subsea equipment such as grabs. Hitherto, providing services to underwater equipment has required the provision of a specific bundle of cable(s) and/or hose(s) dedicated to each application. For some applications, it is known to incorporate the service bundle within an armoured hoist rope. This approach has a number of deficiencies. The resulting rope is costly, gives inferior hoisting properties, and by virtue of limitations on the diameter of rope which can be handled the services which can be incorporated are limited. Further, in practice it is impossible with this arrangement to add to the length of the rope or to join different types of materials, for example wire ropes with fibre ropes. In accordance with an aspect of the present invention, apparatus for use in handling a load comprises a load- bearing rope, a mechanism for paying out and recovering the rope, a drum for holding a service cable with a length of the service cable extending therefrom, and a wrapping device for rotating said length of service cable around the rope as the rope is payed out to wrap the service cable around the rope, and to unwrap the service cable from the rope as the rope is recovered. In accordance with another aspect of the present invention, a method of handling a load comprises paying out a load-bearing rope and wrapping a service cable around the rope as it is payed out, and subsequently unwrapping the service cable from the rope as the rope is recovered. The term "service cable" is used herein to denote a flexible elongate member used for conveying power or data, such as an electrical cable, a fibre optic cable, or a pneumatic or hydraulic hose. Preferably, the service cable is wrapped helically around the rope. Typically, the load-bearing rope will be a hoist rope used for raising and lowering a load. Alternatively, the load-bearing rope may be a towing rope used for paying out, towing and recovering a load such as a marine sensor array. The apparatus may include a plurality of service cables each extending from a respective drum. Preferably, the mechanism for paying out and recovering the rope comprises a rope winch, from which the rope passes over a rope sheave and thereafter extends to the load along a substantially straight axis. The wrapping device may comprise the or each service cable drum being arranged for rotation about a drum axis which coincides with said axis, the drum typically having a central aperture through which the load- bearing rope passes, said length of service cable preferably passing over a service cable sheave which is mounted for movement in a circular path around said axis. Alternatively, the or each service cable drum may be rotatable on a structural member which is arranged for movement in a circular path about said axis. The hoist rope winch, the or each service cable drum, and the wrapping device may conveniently each have a respective driving motor; they could however be driven by a single source through appropriate mechanical linkages. Examples of apparatus and a method for use in handling a load in accordance with the invention will now be described with reference to the drawings, in which:- Fig. 1 is a schematic perspective view illustrating the principle of operation of a first example of the invention; Fig. 2 is a more detailed side view, partly in section, of an apparatus used in the example of Fig. 1; Fig. 3 is a view similar to Fig. 1 illustrating a modification of the arrangement of Fig. 1; Fig. 4 is a schematic perspective view illustrating a second example of the invention; Fig. 5 is a side view of an apparatus used in the example of Fig. 4; Fig. 6 is a schematic perspective view illustrating a third example similar to that of Fig. 1 but modified for towing rather than lifting; and Fig. 7 illustrates a fourth example similar to that of Fig. 4 but modified for towing rather than lifting. Referring to Fig. 1, a hoist rope 1 extends from a hoist rope winch 13 over a hoist rope sheave 4 to support a load (not shown) for raising and lowering. The hoist rope 1 may be any suitable form of hoist rope such as flexible steel wire rope or synthetic fibre rope, for example of "Kevlar". A service cable 2 is reeled on a service cable drum 3 and extends to the load via a service cable sheave 5. The hoist rope 1 passes through a central aperture of the service cable drum 3, and the service cable sheave 5 is arranged to be driven circumferentially around the axis of the service cable 1. By coordinating the movements of the hoist rope winch 13, the service cable drum 3 and the service cable sheave 5, the service cable 2 can be wrapped helically around the hoist rope 1 as the load is lowered, and unwrapped as the load is raised. In this way, a hoist rope of any desired properties can be used in combination with any required service connection. Fig. 2 shows the service cable drum 3 and associated parts in greater detail. The hoist rope sheave 4 is journalled to a fixed frame 20 which is secured to any suitable supporting structure (not shown) . The service cable drum 3 is rotatably mounted on the lower part of the frame 20 and driven in rotation by a motor 6. The inner end of the service cable 2 is connected to the appropriate service by a coupling assembly 8 which comprises a slipring arrangement in the case of electrical or fibre optic services or a rotary coupling in the case of pneumatic or hydraulic services; such rotary couplings are well known per se. The service cable sheave 5 is journalled on a mounting frame 9 which is rotatable about the fixed frame 20 by means of a motor 7. The service cable 2 shown in this embodiment may be a single cable or hose, or may be a specially made cable comprising a plurality of cable(s)/hose(s) . The motors 6 and 7 are driven at speeds related to the axial speed of the hoist rope 1. The speed correlation may be fixed. Preferably, however, this correlation will be controllable to alter both the length of twist (pitch) of the lay of the service cable 2 on the hoist rope 1, and the tension in the service cable 2. Fig. 3 shows a modification in which a second service cable 17 is wrapped on the hoist rope 1 along with the service cable 2. In this modification, the service cables 2, 17 are each provided with a respective storage drum 15, 16 and a respective sheave 5, 14 which may suitably be carried on a common supporting frame for rotation in unison. The apparatus may be further modified by adding further drums and sheaves to handle more services. Fig. 4 illustrates a second example in which the service cable 2 is reeled on a drum 3 and the drum 3 is itself rotated about the hoist rope 1 to achieve a helical wrap and unwrap. As shown in more detail in Fig. 5, the service cable drum 3 may be constituted by a drum 12 removably mounted on a hub motor 11 which is carried on the end of an arm 18 rotatably mounted on the fixed frame 20 and driven by a motor 10. As with the first example, the example shown in Figs. 4 and 5 could be modified by adding further service cable drums to be rotated by the motor 10. Fig. 6 illustrates the example of Fig. 1 modified for use in a marine towing application, for example in paying out, towing and recovering a sensor array such as a sonar sensor or seismographic surveying sensor, the sensor array being towed underwater or on the surface. The service cable drum 3 is hinged to the main structure of the towing vessel (not shown) and can be tilted to a desired towing angle by hydraulic or other mechanisms. Likewise, Fig. 7 illustrates the modification of the example of Fig. 4 for the same use, the frame carrying the mounting arm for the service cable drum 3 being hinged to the vessel and tilted to the desired angle by hydraulic or other mechanisms. The invention may be applied to a system in which one or more service cables is applied to a load-bearing rope which itself carries a service channel in addition to fulfilling its load-bearing function. For example, the load-bearing rope could be a steel wire rope carrying electrical signals, or a rope comprising "Kevlar" load-bearing strands in combination with optical fibre cable. Other modifications may be made within the scope of the invention.

Claims: QLMH& 1. Apparatus for use in handling a load, the apparatus comprising a load-bearing rope (1,19), a mechanism for paying out and recovering the rope (1,19), a drum (3,12,15,16) for holding a service cable (2,17) with a length of the service cable (2,17) extending therefrom, and a wrapping device for rotating said length of service cable (2,17) around the rope (1,19) as the rope is payed out to wrap the service cable (2,17) around the rope, and to unwrap the service cable (2,17) from the rope (1,19) as the rope is recovered. 2. Apparatus according to claim 1, wherein there are a plurality of service cables (2,17) each extending from a respective drum(3,12,15,16) . 3. Apparatus according to claim 1 or claim 2, wherein the means for paying out and recovering the rope (1,19) comprises a rope winch (13), from which the rope (1,19) passes over a rope sheave (14) and thereafter extends to the load along a substantially straight axis. 4. Apparatus according to claim 3, wherein the wrapping device comprises the or each service cable drum (3,12,15,16) being arranged for rotation about a drum axis which coincides with said axis. 5. Apparatus according to claim 4, wherein the or each service cable drum (3,12,15,16) has a central aperture through which the load-bearing rope (1,19) passes. 6. Apparatus according to any of claims 3 to 5, wherein the length of service cable (2,17) passes over a service cable sheave (5,14) which is mounted for movement in a circular path around said axis. 7. Apparatus according to claim 3, wherein the or each service cable drum (3,12,15,16) is rotatable on a structural member (20) which is arranged for movement in a circular path about said axis. 8. Apparatus according to any of claims 3 to 7, wherein the rope winch (13), the or each service cable drum (3,12,15,16) and the wrapping device each have a respective driving motor (6,7,10). 9. Apparatus according to any of claims 3 to 7, wherein the rope winch (13), the or each service cable drum (3,12,15,16) and the wrapping device are driven by a single source through appropriate mechanical linkages. 10. A method for use in handling a load, the method comprising paying out a load-bearing rope and wrapping a service cable around the rope as it is payed out, and subsequently unwrapping the service cable from the rope as the rope is recovered. 11. A method according to claim 10, wherein a plurality of service cables are wrapped around the rope as the rope is payed out.

Inventors: CRAWFORD ALEXANDER CHARLES, CRAWFORD, ALEXANDER, CHARLES
Applicants: CRAWFORD ALEXANDER CHARLES, DEEP WATER RECOVERY & EXPLORAT, CRAWFORD, ALEXANDER, CHARLES, DEEP WATER RECOVERY & EXPLORATION LIMITED
Application year: 1996
Main classification: B66C13
IPC codes: B66C13, B66D1