405.4W Winch Drive Planetary Gearbox Reducer

Every winch drive planetary gearbox installation begins with the same physical constraint: the gearbox must fit inside the cable drum. Drum diameter is set by the cable bending radius. Drum width is set by the cable storage capacity. The axial length available for the gearbox is what remains after the drum barrel, the cheek plates, and the motor adaptor have consumed their share of the envelope. In compact winch designs — telehandlers, small marine cranes, wind turbine nacelle service hoists — that remaining length is often 20-40 mm shorter than what the 405W requires.

The EP-405.4W exists for exactly this situation. It trades 21% of the 405W torque (5,500 vs 7,000 Nm) and narrows the ratio range from 20-80 to 26-57, but gains 20 kg of weight reduction (125 vs 145 kg) and a shorter axial dimension that fits inside drums the 405W cannot enter. And it does this while carrying a proportionally stronger brake — 280 Nm versus the 405W's 270 Nm — providing 5.1% of output torque as brake capacity compared to 3.9% on the larger model.

Telehandler Auxiliary Winches

A telehandler winch mounts inside a drum that lives at the end of a telescopic boom — 15-25 metres from the pivot point. Every kilogram at the boom tip reduces the machine lift capacity by the moment arm ratio: 1 kg at 20 metres reduces the base capacity by the equivalent of 20 kg at the pivot. The 20 kg weight saving of the 405.4W over the 405W effectively recovers 400 kg of lift capacity on a 20-metre boom. In addition, the shorter axial length of the 405.4W allows the drum to fit within the narrower boom cross-section without widening the boom — which would increase wind loading and reduce structural capacity.

Wind Turbine Nacelle Service Hoists

Service winches inside wind turbine nacelles lift replacement components (generator bearings, pitch motors, blade bolts) through the tower to the nacelle level at 80-150 metres. The nacelle interior is tightly packed with the generator, gearbox, and yaw drive, leaving minimal space for the service hoist drum. The 405.4W compact envelope fits inside nacelle hoist drums that the 405W cannot enter. The weight saving is secondary to the dimensional fit — but at nacelle heights, every kilogram of permanent equipment also affects the tower structural design and foundation loads.

Compact Marine Utility Winches

Deck-mounted utility winches on small workboats and patrol vessels where deck space is at a premium. The drum housing must be as compact as possible to leave deck area free for cargo or equipment. The 405.4W allows a smaller drum housing diameter and width compared to the 405W, and the 125 kg total weight keeps the deck load within the vessel stability limits for winch-on-deck installations that were not part of the original vessel design — a common scenario when adding a winch to an existing vessel during a refit.

Telehandler and Rough-Terrain Forklift Winches

Auxiliary winch attachments on telehandlers and rough-terrain forklifts that add hoisting capability to a machine primarily designed for fork-based material handling. The winch drum mounts at or near the boom tip, where every kilogram directly reduces the machine rated capacity. The 405.4W at 125 kg allows the winch attachment to remain within the rated capacity envelope of the telehandler without requiring a capacity derating sticker — which the heavier 405W at 145 kg would trigger on many telehandler models in the 3-4 tonne class.

Wind Turbine Service and Maintenance Hoists

Internal service winches inside wind turbine nacelles and towers used to lift spare parts, tools, and replacement components from ground level to the nacelle at 80-160 metres. The nacelle interior layout is fixed by the turbine OEM, and the service hoist drum space is a defined pocket with rigid dimensional limits. The 405.4W is specified by turbine OEMs who need 5,000+ Nm of drum torque in an envelope that the 405W exceeds by 25-40 mm axially. The slewing drive planetary gearbox handles the yaw drive on the same turbine platform.

Retrofit Marine Deck Winches

Winches added to existing vessels during refits — anchoring upgrades, additional mooring points, or towing capability additions. The existing deck structure was not designed for a winch, so the drum housing must be as compact and light as possible to stay within the deck load allowance and the vessel stability margins. The 405.4W at 125 kg with the proportionally stronger 280 Nm brake provides the torque and holding capacity for a 3-5 tonne marine winch within weight and space limits that the 405W may exceed.

Is the 405.4W a derated version of the 405W?

No. The 405.4W uses a different internal gear geometry optimised for a shorter housing. The gear module size, planet count, and bearing arrangement are not simply a subset of the 405W design — they are a separate gear set engineered for the 26-57 ratio window and the 5,500 Nm output torque. The 405.4W is a purpose-designed compact product, not a 405W with reduced capacity.

Why is the efficiency 94% instead of 95% like the 405W?

The compact housing constrains the gear set to a smaller ring gear diameter, which increases the sliding-to-rolling ratio at the tooth contact. This produces approximately 1% more friction loss per mesh cycle. At 5,500 Nm output and 94% efficiency, the 405.4W dissipates approximately 350 W of heat at full continuous load — compared to approximately 370 W for the 405W at 95% efficiency and 7,000 Nm. The absolute heat generation is actually lower for the 405.4W, despite the lower percentage efficiency, because the total power throughput is lower.

Can the 405.4W and 405W share spare parts?

No. The internal gear sets, bearings, and brake assemblies are different between the two models. The output shaft seal may be the same diameter (verify against the parts list for your serial number), but all other components are model-specific. If your fleet includes both 405W and 405.4W units, stock separate spare parts kits for each. This is one consideration that favours standardising on a single model across the fleet if the dimensional constraints allow it.

What is the maximum SWL on a 300 mm PCD drum with a 4-part reeving?

Maximum line pull at drum = 5,500 / 0.15 = 36,667 N. With 4-part reeving and a 4:1 structural safety factor: SWL = (36,667 x 4) / (4 x 9.81) = approximately 3,735 kg. This covers the majority of telehandler winch and compact marine crane applications. For loads approaching this limit, verify that the brake holding torque (280 x mid-ratio x number of reeving parts) provides the required brake safety factor at the OUTER cable layer, not the first layer. Contact Κορέα Ever-Power for a verified capacity calculation.

How does the winch drive perform in the extreme temperature cycles of a wind turbine nacelle?

A wind turbine nacelle experiences -20 to +60 deg C ambient temperature cycles (the nacelle interior is warmer than external due to generator heat). The 405.4W standard operating range of -20 to +85 deg C covers this envelope with margin. For cold-climate turbines (Arctic, high-altitude), specify the Viton seal kit and SAE 75W-90 full synthetic gear oil, which provides adequate viscosity down to approximately -30 deg C. The brake spring force is temperature-independent (Belleville disc springs, not rubber elements), so brake holding capacity is not affected by cold starts.

Can a winch drive planetary gearbox be used horizontally for a pulling winch instead of vertically for hoisting?

Yes. The 405.4W functions identically in horizontal pull and vertical hoist applications. The oil bath lubrication works at any mounting angle because the housing rotates — the oil is distributed by rotation regardless of the static orientation. In horizontal applications, the brake is typically less critical because the load does not generate a torque from gravity when the motor stops (the load simply remains stationary). However, if the horizontal pull operates on a slope or against a spring-loaded return, the brake must still hold the cable tension. Specify the brake holding torque calculation based on the actual restoring force in the cable, not just the payload weight.

Winch attachment for our 3.5-tonne telehandler. The 405.4W at ratio 35 fits inside the boom-tip drum housing with 12 mm of axial clearance to spare — the 405W would have required a housing extension that fouled the boom telescope overlap. The 20 kg saving kept the winch attachment weight within the rated capacity allowance at 18 metres, which means our customers can use the winch at full boom without a derating sticker on the load chart. The 280 Nm brake holds a 2-tonne suspended load at a safety factor of 3.4 on our 280 mm drum. Twelve units sold in the first quarter with zero field issues.

Internal service hoist for a 4.2 MW offshore wind turbine, nacelle height 110 metres. The 405.4W at ratio 45 lifts replacement pitch motor assemblies (380 kg) at 8 m/min through the tower. The compact envelope was the deciding factor — our nacelle hoist pocket is a legacy dimension from the 3 MW platform and the 405W exceeded it by 28 mm. The unit has completed 14 months of service including the winter maintenance campaign in the North Sea. Cold starts at -12 deg C with SAE 75W-90 oil were smooth and the brake performance has not varied from the commissioning baseline readings. Specifying the 405.4W for the next 80-turbine installation.

Towing winch retrofit on a 28-metre pilot vessel. The vessel was not originally designed for a stern towing winch, so deck load and stability calculations were tight. The 405.4W at 125 kg plus the drum and frame totalled 340 kg — within the 380 kg deck load allowance from the naval architect. The 405W at 145 kg would have pushed the total to 360 kg, leaving almost no margin for the cable weight. The 4-star is about the ratio range: our motor and pump combination wanted a ratio of 22, and the 405.4W minimum is 26. We adjusted the motor displacement slightly to compensate, but if the ratio range started at 20 (like the 405W), the integration would have been cleaner. A compact winch drive with the 405W ratio range of 20-80 would be the ideal product for marine retrofit applications.