Important Considerations for Ship Windlass Maintenance

Views: 272     Author: Lydia     Publish Time: 2023-10-19      Origin: Site


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Important Considerations for Ship Windlass Maintenance

The majority of windlasses seen onboard ships today are powered directly by electric motors or by pressurized hydraulic oil.

They can lift varied loads with the help of gear and tooth arrangement.

The main shaft, driving shaft, inspection cover, gear, gear frame, drums (one or more), warping head or couplings, brake band, brake liner assembly, chain wheel, gear wheel, pinion, clutch, and high speed low speed hydraulic valve blocks are the major components of a windlass.

A ship's officer can estimate the wear and amount of use of this vital machinery by inspecting the exterior and moving portions of the gear and shaft on a regular basis.

Temperature rise on the exterior of hydraulic pipe lines driving the main shaft might be an early sign when employing a windlass for lifting. This needs to be looked into further for the correct technical specifications and qualities of the oil used, as well as the load on the motors and operating pressure of the driving hydraulic fluid. To prevent weather damage, the bearing, pin, and sliding portions of the assembly require a specific lubricant designed for use on open gears. Ship's crew frequently follows the maintenance procedures for the filters of the hydraulic pumps used to power windlasses.

Oil samples are also collected on a regular basis for analysis.

Temperature rise on the main shaft or gear shaft may also indicate a lack of or insufficient lubrication. The primary shaft protrudes from the gear frame and may be outfitted with drums, warping heads, or a cable lifter unit. The shaft is made up of a shaft and pinion as well as a shaft roller bearing that is greased via the grease nipple.

Drums are normally equipped with manual brakes, but they can also be hydraulically actuated. Brakes are attached to the deck via a foundation plate.

Windlass shafts are frequently paired with mooring winches, thus make sure the mooring winch brake is 'on' and the clutch for the winch is in the disengage position before working the windlass.

When the anchoring speed is high, the anchor escapes and the brake lining may be damaged by heat. Dropping the anchor and repeating the drop and halt at every 12 shackle is thus recommended to minimize brake liner damage due to temperature buildup.

To avoid overloading the windlass in rough weather, loosen the anchor chain tension while heaving up with engines. If an excessive weight is placed to the windlass when heaving, return the operating lever to neutral, pay out the cable slightly, increase engine rotations, then heave the chain again once the load has been reduced. Windlass speed changes from high to low produce a considerable speed shift, hence they are built with the most safety precautions possible.

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A loaded Panamax-sized tanker vessel was set to anchor outside the port boundaries at Chittagong anchorage.

While the Master made the decision to let go of the anchor, the mate stationed ahead suggested paying out carefully with the engines. The master heeded his mate's advice, but because he was quite experienced in such situations, he chose to let go of the anchor and use engines to reduce the enormous strains on the windlass. Strong offshore wind and current caused the vessel to swing abruptly and fall astern, and the engine kick forward failed to reduce speed and the heavy weight on cable.  The enormous weight on the cable gave it a jerk to slip while the brake was on, and then the entire length of the cable slipped out, burning the brake liner due to heat and friction, breaking up the bitter end cover inside the chain locker, and dislodging the windlass foundation plate from the deck, causing a massive crack. Fortunately, no one in the forward crew was hurt. As a result, assessing loads on windlasses and cables while in use becomes an important element of the maintenance procedure.

A weekly windlass maintenance program should include lubricating all plain bearings via the grease nipples and gear teeth. Depending on the frequency of use, monthly or quarterly checkups for the condition of brake linings are recommended. All couplings, hydraulic valves, and pipes should be examined for leaks, tightness, and functionality on a monthly basis. Couplings can be protected against rust by wrapping them in anti-corrosive tape. Check the hydraulic motor foundation for tightness and signs of wear at the base.

Bearing clearances, gear wheel contact areas, and hydraulic valves must be adjusted yearly for proper operating pressure. The tightness of the bolts and nuts should be tested. The gear contact should be at least 70% or higher, else the gear wheel would make an unnatural noise. Greasing gear teeth or realigning the windlass can be preventive measures.

Windlass brake settings can be modified when the brake lining has worn away to provide the appropriate holding force. Manufacturers frequently propose replacing a brake lining after a specific drop in thickness. However, when the liner thickness falls within the acceptable limits, the brake setting can be modified with the regulating screw as a temporary remedy. Both the upper and lower linings should be replaced at the same time.

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If the ship's crew is performing the liner replacement at sea, it is critical to secure the chain and anchor with extra lashings. The work should ideally be done in calm waters with no uneven rolling or pitching. The brake system can be checked once the anchor and chain are secured by the stopper and extra lashings. To accomplish this, the brake must be fully opened and all pins connecting to the brake must travel freely; cleaning, greasing, or hammering of pins may be required. The brake nut can be used to change the length of the brake spindle, which corresponds to the thickness of the liner.

It is critical to mark the position of the brake screw down lever and the position of the brake bands corresponding to the brake position when replacing the brake liner assembly of a windlass. Misalignments are frequently noted while reassembling the entire machine after replacing the liner.

The spherical roller bearings attached to the main shaft are precisely manufactured, and they must be removed with care. If any of the roller bearings fail, they must be totally replaced. Never use a steel hammer to strike a roller bearing. To lightly strike it, use a wood hammer or soft hammer.

Finally, the windlass foundation should be inspected after and before each anchoring operation.

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