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Double drum mooring winches

The system composes of 10x brand new Single Drum Winches, 5x Main Drive Units, 10x Fairleads, the Electric Drive and Control Systems, 5x Cooling water sets for dynamic brakes and 5x Control cabins.
The systems were never used are immediately available.

The system is built in accordance with ABS MODU circle-P and rated water depth being 460m (1,500 ft) The winches can store wire rope of 82 mm (3 ¼") x 1,735 m (5,700 ft).

The nominal capacity is  1,250 kN (281 kips) at 9 m/min (30 ft/min) at ½ drum (7th layer).

Pull capacity

  • first layer is 2,020 kN (454 kips) at 5 m/min (16 ft/min)
  • last layer is 830 kN (187 kips) at 13 m/min (43 ft/min)

    The brake capacity (holding) : 6,200 kN (1394 kips)and dynamic : 850 kN (191 kips) at 45 m/min (148 ft/min)

    The drive type is 200 kW AC-driven, VFD control The winch controls are full PLC both local and central.



The mooring winch consists of two drums located beside each other. Both drums are equipped with an individual support frame, a fail-safe band brake, a gearwheel, a pinion and a clutch. The clutch connects the drum to a main drive. Both drums can be clutched to the main drive individually but they are not allowed to be clutched both at the same time. The main drive consists of an electric motor and a parallel gearbox.

1.1 Drum support frame

The drums will be mounted on an individual drum support frame of a robust steel structure, which is partly pinned and partly bolted to a deck foundation. The drum frame will be capable of withstanding forces induced as a result of rope breakage and this will not cause permanent deformation of the drum frame. The frame will be fitted with adequate lifting lugs to lift the complete drum assembly as one unit.

1.2 Drum construction

The drum is designed to accommodate the full length of the steel wire. The drum will be delivered with a spooling pattern welded on the drum and equipped with fillers and risers to accommodate a smooth wrapping sequence. The drum will be capable of withstanding forces as a result of a rope breakage which will not cause permanent deformation to the drum or its components.

1.3 Static brake, band brake

The drum will be equipped with two band brakes, each capable of holding the drum at 50% of the MBL, even during power failure. The band brakes are failsafe, spring set / pneumatic released. Band brake cylinders are “tie rod”  type with stainless steel tie rods, nuts and washers.

1.4 Main gear and pinion

One side of the drum is provided with the main gearwheel in an open construction protected by guard plates with inspection covers and driven by a pinion. The pinion is keyed to the output shaft of the gearbox and can be actuated by means of a clutch.

1.5 Emergency release (controlled)

Emergency release of mooring wire(s) is provided. Air supply shall be provided from the rig's emergency air system for controlled emergency release of the brakes. Manufacurer will specify the air quality, pressure and volume required for acceptable operation. Emergency release of the mooring wire is initiated by a guarded and keyed rotary switch, located at the central control console. The emergency release switch does also sound an audible alarm to warn personnel of an impending hazard. The emergency release switch does also provide a signal to activate the cooling pump (which must be fed from the emergency switchboard), to provide automatic controlled payout of the wire. The emergency release can be stopped by the emergency stop or keyed rotary switch.

1.6 Head pawls / locks

A positive means of locking the winch drums is provided. This will consist of pneumatically engaged locking pins. This locking mechanism is for the purpose of servicing, as well as for abandoning the rig and is designed for 100% of MBL.

1.7 Pneumatic system

Each drum is provided with a pneumatic system, mounted on the drum frame including all valves, switches, filters for the proper control of the brakes and clutches. The unit will be supplied with rig air of sufficient quality. Additional filter units will be part of the system to ensure proper operation.

1.8 Grease system

On each drum an independent grease system will be installed. This system will provide greasing of the main gearwheel during operation. An electric driven grease pump, with timer and reservoir will be mounted in a splash water tight box on each drum frame. Stainless steel piping will be used. All other mechanical elements with moving, sliding or rotating relative motion will be serviceable by grease fitting or some other equivalent lubrication method.

1.9 Electric motor

The motor is suitable for harsh offshore environment and includes stand still heating, encoder feedback and appropriate cable glands.

1.10 Frequency converter system

All frequency converters have to be placed below deck in an air-conditioned room (yard supply). Reverse energy during lowering will be absorbed by resistor banks or fed back into the network (decided during engineering stage).

1.11 Gearbox

The gear case is steel fabrication, horizontal, totally enclosed and splash lubricated. All gears and pinions are machine cut and designed to duty cycles and gear quality according DIN standards. All shafts rotate in anti-friction bearings. The gearbox is equipped with an air-operated speed selecting gearshift and motor - disconnect clutch.

1.12 Gearbox Static / dynamic brake (high speed), water cooled copper disc


To enable high speed pay-out, a water cooled multi-disc brake unit will be mounted on the gearbox. This brake unit will allow high speed pay-out and emergency release of the winches. The water cooled disc brake is operated by modulated air pressure to handle the dynamic pay out of the wire rope under controlled line pull and -speed.



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