Anchor Windlass: Types, Selection & Maintenance Guide

An anchor windlass is one of the most critical pieces of deck machinery on any vessel. Understanding its parts — by name, by function, and by failure mode — is essential for officers, engineers, and procurement teams who need to order replacements or plan overhauls. This guide identifies every major component of a marine anchor windlass with labeled diagrams and practical notes.

Main Components of an Anchor Windlass

A typical electric or hydraulic anchor windlass consists of the following major assemblies, listed from top (deck level) to bottom (below deck):

1. Wildcat (Gypsy Wheel / Cable Lifter) — the toothed wheel that engages the anchor chain
2. Warping drum (Capstan Head) — smooth drum for handling mooring ropes
3. Band brake assembly — holds the chain under load when the windlass is not powered
4. Clutch mechanism — engages or disengages the wildcat from the drive shaft
5. Drive shaft & bearings — transmits torque from the motor/hydraulic unit to the wildcat
6. Reduction gearbox — reduces motor speed and increases torque
7. Electric motor or hydraulic motor — the prime mover
8. Foundation frame & mounting bolts — secures the windlass to the deck

1. Wildcat (Gypsy Wheel / Cable Lifter)

The wildcat — also called the gypsy wheel, chain wheel, or cable lifter — is the most recognizable part of an anchor windlass. It is a cast steel wheel with precisely machined pockets that match the link profile and pitch of the vessel's anchor chain.

Key specifications:

• Chain caliber: 12.5 mm to 120+ mm (must match vessel's chain certificate exactly)
• Material: cast steel ZG270-500 or ZG310-570, sometimes forged for high-load applications
• Number of pockets: typically 5 or 6, depending on chain size
• Surface treatment: flame-hardened pockets for wear resistance

The wildcat is the highest-wear component on the windlass. When the pockets become worn, the chain slips under load — a serious safety hazard during anchoring. Wildcats are manufactured to match a specific chain certificate, so replacement requires the chain caliber, link pitch, and classification society standard (ISO 1704 / IACS UR W18).

Hicool supplies custom CNC-machined gypsy wheels for chain sizes from 12 mm to 120 mm, matched to your chain certificate.

2. Warping Drum (Capstan Head)

The warping drum sits above or beside the wildcat and provides a smooth cylindrical surface for handling mooring lines. During berthing, the crew wraps mooring ropes around the drum and the windlass motor hauls them in. The drum is welded from Q345B steel plate and machined to ensure a smooth rope-gripping surface.

On combined anchor windlass-mooring winch units, the warping drum is usually mounted on the same shaft as the wildcat, with a clutch in between so each can operate independently.

3. Band Brake Assembly

The band brake is a critical safety component. It wraps around the brake drum (integral with the wildcat hub) and holds the anchor chain under static load when the windlass motor is off. The brake must be capable of holding the combined weight of the anchor plus the full scope of chain in the chain locker.

Components of the band brake:

• Brake band — a steel strap lined with friction material (woven asbestos-free lining)
• Brake drum — machined surface on the wildcat hub
• Screw adjuster — worm gear mechanism operated by handwheel
• Operating handwheel — manual control for tightening/releasing the brake

Brake bands are a routine replacement item. When the friction lining wears thin, braking force decreases and the chain can run out uncontrolled during anchoring. Hicool supplies replacement brake bands and brake parts for all common windlass models.

4. Clutch Mechanism

The clutch connects or disconnects the wildcat from the power drive. When the clutch is engaged, the motor drives the wildcat to heave in or pay out chain under power. When disengaged, the wildcat can rotate freely — allowing the chain to run out under gravity during anchor deployment (controlled by the band brake).

Clutch types:

• Jaw clutch (dog clutch) — positive engagement via interlocking teeth. Most common on windlasses. Engaged/disengaged by a handwheel that moves the clutch collar axially along the shaft.
• Friction clutch — used on some hydraulic windlasses for smoother engagement under load.

The clutch must never be engaged or disengaged while the windlass is under load. Doing so can strip the jaw teeth or damage the shaft splines.

5. Drive Shaft & Bearings

The main shaft (also called the windlass shaft or crosshead shaft) runs horizontally through the windlass, connecting the motor/gearbox output to the wildcat and warping drum. It is supported by two or more self-aligning roller bearings housed in the windlass frame.

Shaft material is typically forged 45# steel or 40Cr alloy steel, heat-treated for strength. The shaft is keyed to both the wildcat and the gearbox output flange. Bearing failure is relatively rare but causes serious downtime — regular greasing per the manufacturer's schedule is essential.

6. Reduction Gearbox

The gearbox reduces the high-speed motor output (typically 1,000–1,500 RPM) to the low-speed, high-torque rotation needed by the wildcat (typically 8–15 RPM). Most marine windlasses use one of two gearbox types:

• Planetary gear reducer — compact, high ratio, commonly used on electric windlasses. Installed vertically below deck with oil lubrication.
• Worm gear reducer — self-locking (prevents back-drive), used on some older designs. Less efficient but provides inherent holding capability.

The gearbox is a sealed unit that requires periodic oil level checks and oil changes per manufacturer recommendations (typically every 2,000–4,000 running hours).

7. Electric Motor vs Hydraulic Motor

The choice between electric and hydraulic drive depends on vessel size, available power, and operational requirements.

Feature	Electric Drive	Hydraulic Drive
Common on	Bulk carriers, container ships, general cargo	Tankers, offshore vessels, large tonnage
Motor type	Three-phase AC, IP56, with brake	Axial piston or radial piston
Speed control	2-speed or VFD	Variable displacement pump
Maintenance	Motor brushes, brake pads	Hydraulic oil, seals, filters
Advantage	Simpler, lower maintenance	Smoother control, higher power density

For more detail on drive mechanisms, see our guide on how anchor windlass works.

8. Foundation Frame & Mounting

The windlass foundation is a heavy steel structure welded to the foredeck. It must withstand the full static and dynamic loads from anchoring operations, including shock loads when the chain snubs. The foundation design is approved by the classification society as part of the ship's structural drawings.

The windlass is bolted to the foundation using high-tensile bolts (typically M24–M36, grade 8.8 or 10.9). Bolt holes are reamed for a precise fit. During drydock surveys, inspectors check bolt tightness and foundation welds for cracks.

Chain Stopper & Accessories

While not part of the windlass itself, several accessories work together with it:

• Chain stopper (devil's claw) — holds the chain independently of the windlass brake, used when the vessel is at anchor for extended periods
• Chain pipe & spurling pipe — guides the chain from the wildcat down into the chain locker
• Chain locker — below-deck compartment that stores the anchor chain
• Anchor lashing gear — secures the anchor in the hawse pipe for sea passages

Common Spare Parts & Replacement Schedule

Part	Typical Life	Replacement Trigger
Wildcat (gypsy wheel)	10–15 years	Pocket wear >10%, chain slippage
Brake band & lining	3–5 years	Lining thickness below minimum, reduced holding force
Clutch jaw teeth	10–15 years	Chipped or worn teeth, difficulty engaging
Shaft bearings	8–12 years	Abnormal noise, vibration, overheating
Gearbox oil seals	5–8 years	Oil leakage at shaft or housing joints
Motor brake pads	3–5 years	Motor does not hold when stopped
Foundation bolts	Ship's life	Corrosion, loose torque at survey

How to Order Replacement Windlass Parts

When ordering windlass spare parts, provide the following information to your supplier:

• Windlass maker and model number (from the nameplate)
• Chain caliber and grade (e.g., 78mm Grade U3)
• Classification society (CCS, BV, ABS, DNV, LR, NK)
• Drawing number (if available from the maker's spare parts catalog)
• Quantity and delivery port

Hicool supplies OEM-compatible anchor windlass parts for all major makers. Our recent projects include custom gypsy wheels and brake band assemblies delivered worldwide. Contact us for a quotation matched to your windlass specifications.

Related Anchor Windlass Guides

• How Anchor Windlass Works: Mechanism & Key Components — understand the hydraulic and electric drive systems
• Anchor Windlass Operation Manual — step-by-step operation, maintenance, and troubleshooting