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THE WINDLASS

Sketch and describes a windlass driving two de-clutchable cable lifters and waring dru!s

"urose of a windlass

The duty of the windlass is to lift the anchors and assist in warping the ship and therefore its size andpower depend upon the masses of the anchors and cable, and full load hauling, which is governed bythe size of the ship. It may be powered by a steam engine or electric motors.

E#lain the gearing necessar$ between the ri!e !over and cable liftersThe design and performance of anchor windlasses is subject to approval by a classification society.The basic design is that of a double-purchase lifting machine consisting of a primary shaft,intermediate shaft, and two main halfshafts, with corresponding inions and gear wheelsas showndiagrammatically in figure below. In the electrically driven windlass, the primary shaft is driven bywor! and wor!wheelthrough a worm shaft, from the electric or hydraulic motors.

Due to the low speed of rotation required of the cable lifter whilst heaving anchor !-" rev#min$ ahigh gear reduction is needed when a high-speed electric or hydraulic motor drives the windlass. Thisis generally obtained by using a high ratio worm gear followed by a single step of spur gears betweenthe warpend shaft and cable lifters

The primary shaft carries a pinion which meshes with a gear wheel on the intermediate shaft, and twopinions on the intermediate shaft mesh with two main gear wheels, one on each main half shaft. %achmain half shaft carries a cable-lifter which has snugs around its circumference of the size and pitch tosuit the lin&s of the cable.

The cable-lifters are not fi'ed on the shafts but are mounted freely to allow them to rotate

independent of the shafts. ( screw-operated steel band brakeis fitted around a bra&e drum on theouter edge of the rim of the cable-lifter for controlling the speed of the cable when )paying out) andfor loc&ing it stationary when required.

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The power for hoisting is transmitted through a clutch for!ed b$ %awson the side of the main gearwheel which fit a corresponding set of jaws on the side of the cable-lifter. The main gear wheel may

be a sliding fit and &eyed to its half shaft to allow it to be moved laterally into and out of gear,alternatively the gear wheel may be fi'ed on the shaft and the cable-lifter moved laterally to engagegear. ( screwed control rod attached to a cod-piece riding in a groove in the boss of either the main

gear wheel or the cable-lifteroperates the clutch. Thus the two cable-lifters are entirelyindependent, the anchors may be lifted both at once, or separately, or one may be lifted while theother is being )let go.) %ach end of the intermediate shaft is e'tended through a dog clutch to carry awarping drum.

Anchor handlingThe efficient wor&ing of the anchor windlass is essential to the safety of the ship. (n anchor windlasscan e'pect to fulfil the following*

The windlass cable lifter bra&es must be able to control the running anchor and cable when the cablelifter is disconnected from the gearing when +letting go+. (verage cable speeds vary between " and

m#s during this operation.

The windlass must be able to heave a certain weight of cable at a specified speed. This full load dutyof the windlass varies and may be as high as tonne figures between / and 0 tonne are notunusual. 1ommonly the load is between 0 and 2 times the weight of one anchor. The speed of haul isat least 3 m#min and up to 4" m#min.

The bra&ing effort obtained at the cable lifter must be at least equal to 05 of the brea&ing strengthof the cable.

6ost anchor handling equipment incorporates war endsfor mooring purposes and light line speedsof up to ." to 4. m#s are required. The conventional types of equipment in use are as follows.

&aintenance

Windlass brakesmust be &ept in satisfactory condition if they are to function properly. 7ear andcompression of bra&e linings increases the clearance between the bra&e drum and band after awindlass has been in operation. Inspect bra&e linings and clearances frequently. 6a&e adjustmentsaccording to the manufacturer+s instructions.

Lubricationinstructions furnished by the manufacturer should be followed. If a windlass has beenidle for some time, lubricate it. This protects finished surfaces from corrosion and prevents seizure ofmoving parts.