ZL120 Winch Drive Planetary Gearbox

The 414W3 wins when:

The application sustains 133,000-140,000 Nm for hours without rest (mining main production at deep shafts, AHTS anchor chain holding). The Arctic -40 deg C rating is required. An internal brake is mandated. The FEM M6 certification is needed for the specific regulatory framework.

The ZL120 wins when:

The duty is cyclic (crane hoisting, marine winch operations). The sustained load stays below 133,000 Nm with transient peaks up to 280,000 Nm. Regen braking and energy recovery are commercially valuable. Low noise matters. The motor must be compact and lightweight. Ratios above 300 are needed.

What 100 kW Pt Means

A 100 kW thermal limit at 1-stage means the ZL120 can continuously transmit 100 kW of shaft power without exceeding 85 deg C oil temperature in still air at 20 deg C ambient. For a 1-stage gearbox at ratio 5 with a 5,000 rpm motor: 100 kW at 1,000 rpm output = 955 Nm of continuous thermal-limited torque — far below the 133,000 Nm mechanical limit. At 2-stage ratio 80 with a 3,000 rpm motor: 75 kW at 37.5 rpm output = 19,099 Nm thermal-limited. The thermal limit is typically the binding constraint for high-duty-cycle applications, not the mechanical torque limit.

Practical Sizing at 2-Stage for 80 t Crane

An 80 t electric crane at 40% average duty cycle with a 600 kW motor: average thermal load = 600 x 0.40 x (1 - 0.97) = 7.2 kW (at 97% efficiency at 2-stage). This is well within the 75 kW 2-stage Pt — no external cooler needed for this crane. But at 80% average duty cycle (harbour container crane running near-continuously): average thermal load = 600 x 0.80 x 0.03 = 14.4 kW — still within the 75 kW limit. The ZL120 100 kW Pt class makes external cooling unnecessary for the vast majority of crane applications. External coolers become relevant only at sustained 70%+ duty with motors above 500 kW at 3+ stages.

Where the Cooler Is Still Mandatory

Mining production winders operating at 60-80% of continuous torque for 16-24 hours per day. Mooring winches maintaining constant tension for weeks. Any application where the thermal load exceeds the stage-specific Pt for more than 2 consecutive hours. The external oil cooler (+50-100% Pt) brings the effective thermal capacity to 150-200 kW at 1-stage — sufficient for any application within the 133,000 Nm mechanical limit. Contact Korea Ever-Power for cooler sizing at your specific duty profile.

Electric Heavy-Lift Vessel Cranes (80-120 t SWL)

All-electric cranes on the next generation of offshore construction and heavy-lift vessels where the vessel builder has committed to electric propulsion and demands an all-electric crane to match. The ZL120 at ratio 80-200, 2-3 stage, with 600-1,000 kW high-speed motors provides the hoist torque that previously required the 414W3 mega-class plus a multi-motor hydraulic power unit. The slewing drive a wheel drive complete the all-electric crane on the same electric vessel.

Electric Mining Main Production Winders

Main production winders at mines with shaft depths of 500-900 metres where the sustained drum torque stays within 133,000 Nm. The ZL120 with 5,000 rpm input paired with a compact high-speed AC motor (600-900 kW, IEC 315-400 frame) provides the winding torque with regen recovery of 20-35% of the hoist energy. For mines at this depth range, the ZL120 eliminates the need for the 414W3 mega-class and its associated 1,250 kg housing weight and hydraulic infrastructure.

Large Electric Industrial Overhead Cranes

Electric overhead travelling cranes in steelworks, power stations, and shipbuilding halls handling 50-100 tonne loads at high cycle rates. The ZL120 at ratio 60-150 provides the hoist torque with the helical-quiet operation that enclosed industrial environments demand. The 280,000 Nm peak handles the dynamic loads from ladle engagement, mould clamping, and module positioning that produce transient torques up to 2x the continuous lifting load. The 100 kW Pt at 1-stage means the crane operates without external cooling at typical industrial duty cycles.

Can the ZL120 fully replace the 414W3 for mining production winding?

Only if the sustained drum torque stays below 133,000 Nm. For mines at 500-800 metre depths with 15-20 tonne skip loads and moderate rope weights, the sustained torque typically falls within 80,000-130,000 Nm — within the ZL120 continuous. For mines at 800-1,500+ metres where the rope weight alone adds 50,000-100,000 Nm to the drum torque, the 414W3 at 140,000 Nm continuous (or the larger 4xxW models) remains necessary. The ZL120 replaces the 414W3 at moderate-depth mines, not at ultra-deep mines.

Does the ZL120 meet offshore classification requirements without an internal brake?

Yes, for crane duty. The ZL120 with motor electromagnetic brake plus external drum calliper satisfies DNV, BV, ABS, and Lloyd's requirements for two independent braking means. The classification approval process is identical to the ZL45-ZL95 models — the braking architecture is assessed at the crane system level, not at the gearbox component level. For heavy-lift cranes above 50 tonnes, some class societies require a third braking means — typically VFD dynamic braking with SIL-2 safe-torque-off — which the electric drive inherently provides.

What motor frame is typical for a 100 t crane with the ZL120?

At ratio 100 with a 600 mm PCD drum, 10-part reeving, SWL 100 t at 12 m/min: motor power approximately 800-1,000 kW. At 5,000 rpm: IEC 355 frame (approximately 900-1,100 kg). At 3,000 rpm: IEC 400 frame (approximately 1,300-1,600 kg). The 5,000 rpm input capability saves 300-500 kg of motor weight — which at the crane head translates to 900-1,500 kg of structural and counterweight savings across the crane. For a 100 t crane, this weight saving can be the difference between a standard crane rating and a "heavy-lift" classification that increases the structural cost by 15-25%.

How does the ZL120 ratio 5,440 compare to the ZL95 ratio 4,800?

A 13% increase in maximum ratio. At ratio 5,440 with 3,000 rpm motor on a 300 mm PCD drum: 0.52 m/min (8.7 mm/sec). The practical benefit over ratio 4,800 (0.59 m/min) is marginal for most applications — the additional 13% reduction adds approximately 1 mm/sec of speed difference. The primary advantage of the ZL120 over the ZL95 at high ratios is the 16% higher continuous torque (133,000 vs 115,000 Nm), which enables heavier instrument packages and longer cable deployments at the ultra-slow speeds.

What is the expected overhaul interval for the ZL120 at heavy electric crane duty?

The ZL120 is life-rated at 100,000 hours (N2xh=100,000). At typical heavy crane duty (2,000-4,000 hours per year, 40-60% utilisation): overhaul at approximately 25,000-30,000 hours. The helical gear contact pattern extends gear life by 10-20% versus straight-cut equivalents. Oil changes every 2,000 hours. Seal replacement at 10,000-15,000 hours. Output bearing inspection at 15,000-20,000 hours. The gear set typically survives to the second overhaul (50,000+ hours) before replacement is needed. Contact Korea Ever-Power for the maintenance schedule at your specific duty profile.

How does the 100 kW Pt at 1-stage compare to the ZL95 (90 kW)?

An 11% increase — attributable to the ZL120 larger housing surface area and the greater thermal mass of the heavier casting. At 2-stage: ZL120 approximately 75 kW vs ZL95 approximately 68 kW — a 10% increase. At 5-stage: both approximately 27 kW — the deep-ratio thermal limit converges because the additional housing mass cannot dissipate the heat generated by five gear meshes significantly faster than the ZL95. For high-stage-count applications at sustained duty, external cooling sizing is similar between the ZL95 and ZL120.

100 t all-electric offshore construction vessel crane — the largest all-electric crane currently in operation. ZL120 at ratio 110, 2-stage, 900 kW PMSM at 4,800 rpm. The crane replaced a 414W3 hydraulic specification during the vessel design phase after the vessel builder committed to an all-electric power system. Weight saving at the crane head: 680 kg (ZL120 + motor vs 414W3 + HPU + dual motors + cooler). The naval architect used this saving to increase the crane boom length by 2.5 metres. The ZL120 280,000 Nm peak handled the proof-load test (125 t at 1.25x factor) without any VFD overcurrent event. Regen recovery over 9 months: 22% of total crane energy consumption. The vessel operator has stated this is the last hydraulic crane they will specify.

Main production winder at a 650-metre zinc mine, ZL120 at ratio 280, 3-stage, 700 kW AC motor at 4,500 rpm. The skip carries 18 tonnes of ore; rope weight at full depth is 3,200 kg. Sustained drum torque during loaded hoist: 105,000 Nm — 79% of the ZL120 continuous rating. The 414W3 was the original specification, but the mine engineering team switched to the ZL120 after the regen braking analysis showed a projected annual energy saving of USD 280,000 (28% recovery x 350 cycles/day x 300 days/year x average 22 kWh recoverable per cycle). The ZL120 gearbox cost premium over the 414W3 was recovered in 4.5 months of regen savings.

80 t electric overhead crane in a steelworks continuous casting bay, ZL120 at ratio 80, 2-stage, 600 kW AC motor. The crane handles 70-tonne ladle transfers at 120 cycles per day. The ZL120 helical gear noise at 62 dB(A) is a significant improvement over the previous straight-cut gear noise at 78 dB(A) — the operators can now hear the overhead intercom during crane travel, which was impossible with the old gearbox. The 280,000 Nm peak absorbs the ladle engagement shock (measured at 1.8x continuous) without audible gear stress. The 4-star reflects a spare parts observation: we operate three ZL120 units and two ZL85 units on different cranes in the same bay. Despite both being ZL series, zero internal components are interchangeable between the two model sizes. For plants operating multiple ZL models, reducing the internal component overlap between adjacent models (even partially — shared seals or bearings) would simplify our spare parts inventory.