406W Winch Drive Planetary Gearbox Reducer

406W — The Production Standard

13,000 Nm. Ratios 28-140. Pure two-stage. The winch drive planetary gearbox that crane OEMs specify when the hoist speed is known, the duty cycle is defined, and the priority is consistent, repeatable performance across a production fleet.

Every additional planetary stage adds three planet gears, one sun gear, one ring gear segment, two sets of planet bearings, and one carrier assembly. Each of those components introduces a potential failure mode — a gear tooth that could pit, a bearing that could spall, a carrier pin that could fatigue. The 406W eliminates an entire stage compared to the 406AW three-stage variants and the 406BW3.

For a single prototype crane, the reliability difference between two and three stages is academic. For a production run of 200 cranes — each running 4,000 hours per year for 15 years — the statistical effect is measurable. Fewer components means fewer opportunities for manufacturing variation to produce an outlier unit, fewer surfaces for wear particles to generate, and fewer items on the overhaul inspection list. The 406W two-stage architecture is the production engineer's preference when the ratio requirement falls within 28-140.

Production Mobile Cranes (15-30 t SWL)

All-terrain, rough-terrain, and truck-mounted cranes manufactured in annual volumes of 50-500 units. The 406W at ratio 40-60 provides the main hoist torque for these cranes at production-friendly consistency — every unit off the assembly line performs identically because every 406W uses the same two-stage architecture with the same component count. The slewing drive handles superstructure rotation, and the wheel drive propels the carrier — all from the same Korea Ever-Power catalogue.

Standard Offshore Platform Cranes

Class-certified pedestal and knuckle-boom cranes in the 10-20 t SWL range — the most common offshore crane size class globally. The 406W at ratio 60-100 provides the hoisting torque and the 430 Nm brake provides the holding capacity for standard supply vessel cargo transfer and module handling. The pure two-stage architecture simplifies the classification documentation because the internal gear train has fewer components to document, inspect, and certify during the factory acceptance test.

Tower Crane Main Hoists

Main hoist mechanisms on construction tower cranes with tip loads of 2-5 tonnes and maximum loads of 10-15 tonnes. The 406W at ratio 80-140 provides the torque for heavy-load, slow-speed lifting at maximum radius and the motor can be overspeeded at light loads for faster cycle times at minimum radius. The two-stage architecture keeps the axial length shorter than a three-stage equivalent, allowing the hoist drum to fit within the standard tower crane machinery platform width without structural modification.

Why does the 406W weigh 30 kg more than the 406AW despite producing only 500 Nm more torque?

The 406W uses a larger-module gear set with wider face widths than the 406AW two-stage configuration. The additional gear material carries the 500 Nm torque increase but also provides greater thermal mass for sustained heavy-duty cycles. The 406AW at 210 kg achieves its lighter weight partly by using smaller gears (adequate for 12,500 Nm) and partly because the three-stage high-ratio variants distribute the torque across more stages, allowing each stage to use smaller, lighter gears. The 406W concentrates all 13,000 Nm across just two stages, requiring heavier gears per stage.

How does the 406W two-stage noise level compare to the 406BW3 three-stage at the same output speed?

At the same drum output speed, the 406W input shaft rotates slower than the 406BW3 because it achieves the ratio in fewer stages with higher per-stage reduction — meaning each stage operates at a lower mesh frequency. Lower mesh frequency generally produces lower-pitched noise but at slightly higher amplitude per mesh event. The three-stage 406BW3 produces higher-pitched but smoother noise because each stage contributes a smaller mesh event at higher frequency. Subjectively, the 406W sounds "gruntier" and the 406BW3 sounds "whiner." Objectively, both measure within 2-3 dB(A) of each other at equivalent operating conditions.

What crane SWL range does the 406W typically serve?

Depending on drum diameter, reeving, and safety factor: approximately 8-25 tonne SWL for general crane hoisting. On a 400 mm PCD drum with single-line reeving and a 4:1 safety factor: SWL = 13,000 / (0.2 x 4 x 9.81) = approximately 1,660 kg. With 4-part reeving: SWL = 6,640 kg. With 8-part reeving (common for cranes above 15 tonnes): SWL = 13,280 kg. The 406W is the standard choice for cranes in the 10-20 tonne production class.

Can a winch drive planetary gearbox from the 406 family be field-converted between ratio variants?

Not practically. The gear sets are ratio-specific — changing the ratio requires removing and replacing the entire internal gear train, re-setting bearing preloads, and performing a dynamometer load test. This is effectively a factory overhaul, not a field conversion. If future ratio flexibility is needed, specify the 406AW with its wider range or select the 406W ratio with the widest operational margin so that motor speed adjustment can compensate for minor speed changes without touching the gearbox.

What is the expected MTBF for the 406W at sustained FEM M5 duty?

At FEM M5 duty with full maintenance compliance: target first overhaul at 20,000-25,000 hours. The two-stage architecture historically shows 10-15% longer MTBF than equivalent three-stage models of the same torque class — because fewer components produce fewer failure initiators per operating hour. Seal replacement at 10,000-15,000 hours. Brake disc stack at 15,000-25,000 hours. Bearings at 20,000-30,000 hours (L10 life). Oil changes every 2,000 hours. The overhaul typically consists of bearing and seal replacement, brake disc stack renewal, and bearing preload re-setting — the gears themselves rarely require replacement within the design life.

Does the winch drive work in a twin-hoist configuration (two drums, one crane)?

Yes. Many production cranes use a main hoist and an auxiliary hoist, each with an independent drum and winch drive. The 406W is commonly specified for the main hoist, with a smaller model (405W at 7,000 Nm or 403W2 at 4,000 Nm) for the auxiliary. Each winch drive operates independently — separate motors, separate hydraulic circuits, separate brakes. The crane control system coordinates the two hoists when needed (for example, during tandem lifting with a spreader beam), but the winch drives themselves have no mechanical or hydraulic coupling.

Main hoist on a 25 t all-terrain crane, annual production volume 120 units. The 406W at ratio 55 has been our standard hoist drive for the current model generation — 480 units delivered across 4 years. Incoming QC rejects: zero. Field warranty claims on the winch drive: 4 (all seal-related, all within the first 500 hours, all traced to a specific silicone sealant batch that has since been replaced). The two-stage architecture produces the most consistent dynamometer test results of any gearbox we source — unit-to-unit torque variation is less than 2%, which is half the tolerance we see on competing three-stage drives.

15 t SWL offshore crane, 406W at ratio 70. The classification process was the smoothest gearbox approval we have handled this year. The two-stage internal drawing is simple enough that our surveyor could verify the tooth count, module, and material specification during the factory witness test in one session. Three-stage units from other suppliers typically require two sessions because the additional stage components increase the inspection scope. The 406W type-approval certificate is now our reference standard for crane hoist drives in this torque class.

Main hoist on a luffing-jib tower crane, 12 t maximum capacity, 406W at ratio 90. Mechanical performance is excellent — the crane has completed 14 months on a high-rise project with an average of 180 lifts per day. The 4-star is a wish-list item: a factory-supplied commissioning data sheet recording the as-built dynamometer torque, brake holding torque, and oil charge volume would give me a unit-specific baseline to compare against during the annual thorough examination. Currently I use the generic product specification as the baseline, which has slightly wider tolerances than the individual unit actually exhibits. A unit-specific birth certificate would make condition monitoring more precise and potentially extend the interval between invasive inspections.