ZR75 Winch Drive Planetary Gearbox — Right-Angle

ZR75 — 70,000 Nm

The right-angle twin of the most-specified ZL model. Same 70,000 Nm continuous, same 175,000 Nm peak, different motor axis — for every 40-60 t winch drive installation where the coaxial geometry hits a wall.

A hydraulic motor at 160 cc/rev is approximately 200 mm in diameter and 300 mm long — it sits inside the drum cavity behind the gearbox. An electric motor at 400 kW is approximately 500 mm in diameter and 700 mm long — it projects far beyond the drum cavity into the machinery room. If the machinery room has 400-600 mm of free space behind the drum (common on offshore platform cranes and harbour cranes built in the 1990s-2010s), the electric motor does not fit coaxially. The ZR75 redirects the motor perpendicular — fitting a 700 mm long motor into the 1,200-2,000 mm of lateral space that most machinery rooms provide beside the drum.

By avoiding structural modification to the machinery room: typically USD 50,000-200,000 in steel work, welding, NDT, and re-certification — depending on whether the structure is a vessel (class survey required), an offshore platform (structural modification permit required), or a harbour crane (less costly but still significant). The ZR75 pays for itself in structural modification avoidance before the first lift is made.

Step 1: Measure the axial depth behind the drum. Step 2: If the electric motor fits coaxially, specify ZL75. Step 3: If it does not, specify ZR75. Both deliver 70,000 Nm / 175,000 Nm. Both use the same DIN 5-6 helical planetary stages. The only difference is the input geometry and the 500 rpm lower input speed (3,100 vs 4,000 for ZL75). Contact 한국 에버파워 with your machinery room dimensions for a geometry recommendation.

Offshore Platform Crane Conversions (40-60 t)

Mid-life hydraulic-to-electric conversions on offshore platform cranes where the existing deck layout, structural penetrations, and machinery room geometry are fixed. The ZR75 is the model that makes these conversions physically possible without structural redesign — delivering the same 70,000 Nm torque and 175,000 Nm peak as the coaxial ZL75 through a geometry that fits the existing space. The slewing drive conversion follows on the same platform.

Large Marine Deck Winches

Anchor handling, towing, and mooring winches on vessels where the drum axis runs athwartship and the motor must mount fore-and-aft. The ZR75 at 70,000 Nm provides the main deck winch torque for vessels in the 5,000-15,000 DWT range — cargo ships, offshore support vessels, and multi-purpose vessels. The 3,100 rpm input matches the 4-pole AC motors that vessel electrical systems standardise on. The IP67+ sealing survives the deck-mounted marine environment.

Heavy Industrial Hoists in Existing Buildings

Overhead crane hoist replacements in steelworks, power stations, and heavy manufacturing plants where the crane bridge beam limits the axial depth above the drum. The ZR75 mounts the motor horizontally alongside the drum, keeping the total height within the existing crane bridge clearance. For industrial modernisation programmes where the building structure cannot be modified, the ZR right-angle geometry is often the only way to upgrade the hoist drive to electric without raising the roof.

Does the 200 rpm speed reduction (3,100 vs 3,300 on ZR55) affect motor selection?

For 4-pole motors at 50 Hz (3,000 rpm synchronous): no impact — the motor already runs below 3,100 rpm. For 4-pole motors at 60 Hz (3,600 rpm synchronous): the motor must be derated or frequency-limited to 3,100 rpm by the VFD — a standard parameterisation that takes one configuration step. For 2-pole motors at 50 Hz (3,000 rpm synchronous): the motor runs at or below the ZR75 limit. The 3,100 rpm ceiling is compatible with all standard industrial motor speeds without hardware changes.

Can the ZR75 and ZL75 share planetary spare parts?

Yes. The planetary stages (stages 2-5 in ZR75, stages 1-5 in ZL75 at overlapping ratios) share the same gear sets, bearings, carriers, and seals. Only the bevel gear pair, bevel shaft bearings, and input housing section are ZR-specific. For fleet operators running both ZR75 and ZL75 on different cranes, the planetary spare parts are fully interchangeable — significantly reducing the combined inventory requirement.

How much structural modification does the ZR75 typically avoid in a platform crane retrofit?

On a typical offshore platform crane conversion from hydraulic to electric: the ZR75 avoids extending the machinery room aft (which requires cutting and re-welding the deck structure, re-certifying the structural modification, and potentially moving or rerouting piping and cabling behind the new bulkhead position). Estimated cost avoidance: USD 80,000-250,000 depending on the platform type and the classification society survey scope. On harbour and shipyard cranes: USD 30,000-80,000 in structural steel and civil works.

Does the ZR75 right-angle affect the regen braking capability?

No. Regenerative torque flows from the drum through the planetary stages and through the bevel stage to the motor in exactly the same way as hoisting torque flows from the motor to the drum. The bevel stage is bidirectional — it transmits torque equally in both directions with the same efficiency loss (1-2%). The ZR75 regen recovery rate is approximately 1-2% lower than the ZL75 due to the additional bevel mesh loss — a negligible difference in practice (for example, 22% recovery on ZL75 versus 21% on ZR75 at identical duty).

Can the ZR75 motor be mounted in any orientation — horizontal, vertical, inverted?

Yes. The right-angle input accepts the motor in any orientation perpendicular to the drum axis — horizontal (motor beside the drum), vertical (motor above or below), or any intermediate angle. The oil bath lubrication system works in all orientations provided the housing is filled to the correct level for the installed angle. For vertical motor mounting (common on narrow headframes), verify that the motor bearing lubrication system is rated for vertical operation. Contact 한국 에버파워 for the oil fill level at your specific mounting angle.

What overhaul interval applies to the ZR75?

The same 100,000-hour life rating as the ZL75. Target first overhaul at 25,000-30,000 hours. The bevel gear inspection is included in the standard overhaul scope — no separate bevel-specific maintenance is required. Oil changes every 2,000 hours (the bevel and planetary stages share the same oil bath). Seal replacement at 10,000-15,000 hours. For retrofit cranes operating at 2,000-4,000 hours per year, the first overhaul falls at approximately 6-15 years of service. Contact 한국 에버파워 for maintenance scheduling at your specific duty profile.

50 t offshore platform crane, hydraulic-to-electric conversion. The machinery room survey showed 520 mm of free space behind the drum — enough for the hydraulic motor but not for a 400 kW electric motor (680 mm deep). The ZL75 was our first specification; the ZR75 was the rescue. Motor mounted horizontally to starboard of the drum, right-angle input turning the torque into the drum. Zero structural modification. The conversion cost came in 22% under budget because we avoided the deck extension that the ZL75 would have required. After 11 months of operation: same hoisting performance as the ZL75 installations on our newer platforms, 21% regen recovery (versus 23% on the ZL75 — the 2% difference is the bevel mesh loss, exactly as predicted). We are now surveying 6 additional platform cranes for ZR75 conversion.

60 t shipyard gantry crane, ZR75 at ratio 140, 3-stage, 350 kW AC motor mounted vertically below the drum on the gantry trolley. The crane bridge beam is 800 mm deep — no room for a coaxial motor above the drum. The ZR75 vertical motor mounting keeps the total hoist assembly height to 650 mm, fitting within the bridge clearance with 150 mm to spare. The crane positioned a 55-tonne engine block to within 4 mm of the foundation bolts on the first approach — the DIN 5-6 accuracy and the 175,000 Nm peak absorbed the block engagement shock without any perceptible hesitation in the hoist speed. The shipyard has ordered 3 additional ZR75 units for the remaining gantry cranes.

40 t harbour portal crane, ZR75 at ratio 80, 2-stage, 400 kW AC motor. The crane operates 200 metres from a residential area — noise was the primary specification driver. The ZR75 helical gear noise at 64 dB(A) at the operator station is a substantial improvement over the previous hydraulic system at 76 dB(A). The right-angle mounting was necessary because the portal crane machinery house has a steel access stairway 450 mm behind the drum position. The 4-star is a maintenance access observation: the bevel housing on the ZR75 projects laterally from the drum housing, and the oil drain plug for the bevel section is positioned facing the stairway — requiring the crane maintenance team to reach across the stairway handrail to access the drain. Rotating the bevel housing 90 degrees during installation would have positioned the drain plug on the accessible side. For future ZR installations, a commissioning note recommending that the maintenance team verify oil drain accessibility before final bolting would prevent this recurring issue.