ZR85 Winch Drive Planetary Gearbox — Right-Angle

The ZR85 bevel gear pair transmits the 200,000 Nm peak torque through the 90-degree turn without exceeding the tooth bending limit of the DIN 5-6 ground helical bevel gears. The bevel stage at peak produces approximately 4,000-6,000 N of axial thrust on the bevel shaft bearings — absorbed by the heavy-series tapered rollers rated for this exact load at the 100,000-hour design life. The bevel teeth are the most highly stressed components in the ZR85 at peak torque — and they are designed for exactly this condition.

An 80 t crane at 70,000 Nm continuous drum torque encounters a 2.5x grab crane impact: transient = 175,000 Nm. A marine anchor winch at 60,000 Nm continuous encounters a 3.0x snatch load: transient = 180,000 Nm. A mining skip winder at 80,000 Nm encounters a 2.2x skip-loading shock: transient = 176,000 Nm. All three events fall within the ZR85 200,000 Nm peak — absorbed through the bevel stage and planetary stages without exceeding any component limit.

At 88,000 Nm continuous with a 500-700 kW motor, the motor weighs 600-1,000 kg. A coaxial mount places this weight cantilevered behind the drum — creating a bending moment on the drum support bearings. A right-angle mount places the motor weight beside or below the drum — closer to the support structure centre of gravity. For large cranes and marine winches, the right-angle geometry can reduce the drum support structural requirement by 10-20% because the motor weight is better distributed. Contact Kórea Ever-Power for mounting geometry recommendations at your specific installation.

On commercial vessels and offshore support vessels, the main deck winch drum axis conventionally runs athwartship (across the vessel beam). The motor must run fore-and-aft (along the vessel length) to avoid projecting outboard. This is not a space constraint — it is a naval architecture convention that has been standard for a century. Every athwartship deck winch in the 50-80 t class is a ZR application by design, not by default.

In mine headframes, the winder drum sits horizontally while the motor is often mounted vertically on a structural column beside the drum — a compact arrangement that minimises the winder house floor area. The vertical motor mount is a deliberate design choice for headframes with limited floor space, not a compromise. The ZR85 right-angle input connects the vertical motor to the horizontal drum through the 90-degree bevel — the standard geometry for modern compact headframe winder houses.

On large overhead travelling cranes (50-80 t), the hoist drum sits below the crane bridge beam. The available height between the drum and the bridge is typically 400-800 mm — insufficient for a coaxial motor above the drum. The ZR85 mounts the motor horizontally alongside the drum, keeping the total hoist height within the bridge clearance. This is the standard hoist geometry for new-build heavy EOT cranes in steelworks, power stations, and shipbuilding halls.

Heavy Marine Deck Winches (50-80 t Line Pull)

Anchor handling, towing, and mooring winches on vessels where the drum runs athwartship. The ZR85 at ratio 60-150, 2-4 stage, with 400-700 kW motors provides the main deck winch torque for offshore support vessels, anchor handling tugs, and large cargo vessels. The 200,000 Nm peak handles the snatch loads from tow-wire engagement, anchor chain snap-loading, and emergency mooring line tensioning. The slewing drive handles the fairlead and stern roller positioning on the same vessel.

Electric Mining Headframe Winders

Main and auxiliary winders on mine headframes at 300-700 metre shaft depths where the motor mounts vertically on the headframe column. The ZR85 at ratio 100-300 with 300-600 kW motors provides the winding torque with regen recovery and the compact floor-area footprint that modern headframe designs demand. The right-angle geometry eliminates the axial projection of a coaxial motor — reducing the winder house depth by 500-800 mm compared to the ZL85 coaxial equivalent.

Heavy Electric Overhead Cranes (50-80 t)

New-build electric overhead cranes in steelworks, nuclear decommissioning, and heavy manufacturing where the hoist drum sits below the bridge beam with limited vertical clearance above. The ZR85 at ratio 60-120 mounts the motor beside the drum — keeping the total hoist height within 600-800 mm for standard bridge beam clearances. The 200,000 Nm peak absorbs ladle engagement shocks, mould clamping impacts, and heavy load sway forces that the continuous rating alone cannot cover.

Does the bevel stage handle the 200,000 Nm peak reliably at 3,100 rpm?

Yes. The bevel gears are rated for the peak torque at the maximum input speed as a combined loading condition. The 200,000 Nm peak occurs at sub-10-second duration — during which the bevel tooth contact stress briefly reaches approximately 90% of the material endurance limit. The gear steel (20CrMnTi, HRC 58-62) and the DIN 5-6 surface finish ensure the oil film is maintained at the tooth contact point throughout the transient. The bevel gears are not the weakest link in the ZR85 at peak — the output bearing fatigue life is the life-limiting component, identical to the ZL85.

How does the ZR85 motor weight distribution compare to the ZL85 on a crane?

On a coaxial ZL85, the motor weight (600-1,000 kg) is cantilevered behind the drum on the drum shaft axis — creating a bending moment on the drum bearings proportional to the motor weight x the overhang distance. On the ZR85, the motor weight is positioned perpendicular to the drum axis — typically closer to the support structure. The bending moment on the drum bearings from motor weight is reduced by 40-60% on a typical ZR installation, which extends the drum bearing life or allows lighter drum support bearings for the same design life.

Can the ZR85 and ZL85 share planetary spare parts?

Yes — identical to the ZR75/ZL75 parts commonality. The planetary stages share gear sets, bearings, carriers, and seals. Only the bevel stage components are ZR-specific. For fleet operators running ZR85 (marine deck winches) and ZL85 (crane hoists) on the same vessel, one planetary spare parts kit serves both models. Add the ZR-specific bevel gear pair and bearing kit for complete coverage.

What crane SWL does the ZR85 serve at standard reeving?

At 88,000 Nm on a 600 mm PCD drum with 10-part reeving and 4:1 SF: SWL = 88,000 / (0.3 x 9.81 x 4) x 10 x 0.82 (reeving efficiency) = approximately 61,200 kg (61 t). At 8-part reeving: approximately 49,000 kg (49 t). The ZR85 covers the 50-80 t SWL range depending on drum diameter, reeving arrangement, and safety factor. Contact Korea Ever-Power for exact SWL calculations at your specific configuration.

Is the ZR85 suitable for constant-tension mooring winch duty?

Yes, within the 88,000 Nm continuous limit and the thermal power envelope. Constant-tension mooring typically operates at 30-60% of the winch continuous rating for extended periods (weeks or months). At 50% of continuous (44,000 Nm) at 2-stage: the thermal load is well within the 90 kW Pt limit. The ZR85 right-angle geometry is particularly well-suited for mooring winches on vessels where the drum runs athwartship and the motor runs fore-and-aft — the standard mooring winch installation on tankers and FPSOs.

What overhaul interval applies to the ZR85 at heavy marine duty?

Target first overhaul at 20,000-25,000 hours for marine environments (salt spray accelerates seal wear by approximately 20% compared to land-based installations). Oil changes every 1,500 hours in marine service. Seal replacement at 8,000-12,000 hours. Bevel gear inspection at 15,000 hours. The bevel stage in marine service should receive particular attention during oil sampling — monitor for iron particle counts that indicate bevel tooth surface distress. Contact Kórea Ever-Power for the marine-specific maintenance schedule.

Main deck winch on a new-build 120 m offshore support vessel, ZR85 at ratio 100, 3-stage, 500 kW AC motor mounted fore-and-aft while the drum runs athwartship. This is a new-build — the ZR85 was specified from the first general arrangement drawing because the athwartship drum is the naval architecture standard for this vessel class. The 200,000 Nm peak handled the first anchor chain deployment snatch load (measured at 2.4x steady-state by the load cell) without any VFD protection event. Regen during chain recovery: 19% of the deployment energy. The vessel builder has standardised on ZR85 for all deck winches in the 60-80 t class across their next 4 OSV newbuilds.

Main production winder on a new-build compact headframe at a 550-metre chrome mine, ZR85 at ratio 200, 4-stage, 400 kW AC motor mounted vertically on the headframe column. The right-angle geometry reduced the winder house floor area from the planned 4.2 x 3.8 m (ZL85 coaxial) to 3.2 x 3.8 m — saving 3.8 m² of floor space and one headframe column. The mine civil engineering team estimated this saved ZAR 1.2 million in headframe steel and foundation costs. The winder has completed 6 months of production at 280 cycles per day with regen recovery measured at 24% — exceeding the 20% target in the energy budget. Oil analysis trending clean; vibration flat.

70 t overhead crane in a steelworks hot-rolling mill, ZR85 at ratio 80, 2-stage, 600 kW AC motor mounted horizontally beside the drum. The crane bridge beam clearance above the drum is 620 mm — the ZR85 total hoist height is 580 mm with 40 mm to spare. A coaxial ZL85 would have been 920 mm tall, requiring a complete bridge beam redesign costing approximately USD 180,000. The ZR85 saved the bridge and the budget. The 200,000 Nm peak handles the coil-engagement shock (measured at 1.9x continuous) during hot slab pickup. The 4-star is a heat exposure note: the ambient temperature at the drum position reaches 50-55 deg C during rolling. Oil temperature peaks at 76 deg C — within the 85 deg C limit but with less margin than the design temperature of 20 deg C ambient assumed in the Pt calculation. For steelworks installations, quoting the Pt at 50 deg C ambient rather than 20 deg C would give more realistic motor sizing guidance.