Windlass(Construction,Working,Classification Society Rules for Windlass and Chain Stopper)

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Used for handling the Anchor – Pay Out (Drop) & Heave In (Pull Up)

Also used for handling the lines and for warping the ship alongside in a – dock (or) canal locks (or) harbour

 

Construction

It consists of (i) Primary Shaft (ii) Intermediate Shaft & (iii) 2 Main Half Shafts

These Shafts are fitted with corresponding Pinions and Gear wheels

Primary Shaft is driven by Worm & Worm Wheel.

Worm Shaft is coupled to a Hydraulic / Electric Motor

Cable -Lifters are mounted freely (not keyed) on the Main Half Shafts. Hence the cable-lifter can rotate independent of the shaft

Cable –Lifters are provided with Sprocket (projection) on its circumference. Sprockets are engaged with the links of the Anchor Chain / Cable

Brake Band (screw operated) is fitted around the Brake Drum. Break Drum is on the outer edge of the rim of the Cable-Lifter.

Brake Band is used:

(i) to control the speed of the Anchor Chain when paying out (i.e to control the speed of Cable-Lifter) and (ii) for locking the cable in a stationary position

Main Gear Wheels is keyed to the Main Half Shafts

Main Gear Wheel can be moved / slided, to and fro, laterally for Clutching (engaging) and de-Clutching (disengaging) with the Cable-Lifter

Each End of the Intermediate Shaft is connected to a Warping Drum through a Dog Clutch

 

Working

To Pay Out (Drop) the Anchor:

Engage the Main Gear Wheel with the Cable-Lifter

Use Hydraulic / Electric Motor to Slightly Heave In (Pull Up) the Anchor Chain

Remove the Chain Stopper Pawl (Guillotine Bar / Bow Stopper Pawl)

Apply/Tighten the Brake on the Cable-Lifter

Disengage the Main Gear Wheel

Release the Brake.

Control the speed of the cable paying out by using the brake.

(i.e. control the speed of Cable-Lifter by using the brake)

Apply /Tighten the brake on the Cable-Lifter when the Anchor has dropped to the desired depth.

Place the Chain Stopper Pawl in the Chain-Holding Position

Chain Stopper takes the load of the Anchor & Anchor Chain. It avoids load/ stress coming on the Windlass

 

To Heave In (Pull Up) the Anchor:

Engage the Main Gear Wheel

Start the Electric/Hydraulic Motor

Heave In (Pull Up) the Anchor /Anchor Chain by controlling the Motor

(i.e by rotating the Cable-Lifter using the Motor)

Apply / Tighten the brake on the Cable-Lifter when the Anchor is raised

Place the Chain Stopper Pawl in the Chain-Holding position

Basic Marine Engineering Book Page No. 223   Figure  13.1

Basic Marine Engineering Book Page No. 224   Figure  13.2

 

Classification Society Rules for Windlass and Chain Stopper

Windlass should be suitable for the size of Anchor Chain Cable used

Windlass should be of sufficient power

Each Anchor should be provided with One Cable-Lifter

Cable-Lifter should be connected to the Main Gear Wheel (Driving Shaft/ Main Half Shaft) by a Release Coupling (Clutch)

Cable-Lifter is to be provided with a Brake

Each Chain cable should be provided with a Chain Stopper Pawl (between the windlass and the hawse pipe)

Chain Cables from (Chain locker) Spurling Pipe should reach the Hawse Pipe through a Cable-Lifter only

Windlass should have a torque limiting device (slipping clutch)

Windlass should be able to exert a continuous pull for 30 min

(Pull – Force (Newtons) is as per regulations laid down by the Administration)

Windlass should also be able to exert 1.5 times the continuous pull for not less than 2 min

Mean Hosting Speed should not be less than 9 m / min

Windlass brake should be sufficient for safe stopping of the anchor chain cable when paying out

With Brakes Engaged and Release Coupling Disengaged – Windlass should be able to withstand a pull of 45 % of the breaking strength of the chain cable without any permanent deformation of the stressed parts and without break slip

Chain Stopper and their attachments should be able to withstand a static pull of 80 % of the breaking strength of the chain cable without any permanent deformation of the stressed parts

 

 

Electrical or Electro Hydraulic Drives is used in Windlass

 

Slipping Clutch / Torque Limiting Device

When Anchor is Heaved In (Pulled Up), the Anchor Cable gets housed in the Hawse Pipe

Some time the anchor cable comes to a sudden stop

Example – Anchor reaching the End of the Hawse Pipe

But Electric/Hydraulic motor continues to rotate due to rotational inertia

i.e one end of the machinery has come to a sudden stop  while the other end of the machinery is still rotating

This causes excessive stresses/shock load on the motor

To avoid this -Slipping clutch is fitted between the Motor and the Gearing

When the windlass gearing side shaft comes to a sudden stop – the motor side of the shaft will slip and continue to rotate

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