ZL95 Winch Drive Planetary Gearbox

Shaft power = torque x speed. At 4,000 rpm, a 600 kW motor produces 1,432 Nm of input torque. At 5,000 rpm, the same 600 kW produces 1,146 Nm — a smaller motor frame achieves the same power because it runs faster. Alternatively, the 5,000 rpm motor produces 25% more power from the same frame: 750 kW instead of 600 kW. For crane OEMs, this means the ZL95 can be paired with the same motor frame as the smaller ZL85 while delivering 31% more continuous torque — or the motor frame can shrink by one IEC size for the same torque output.

A typical IEC 355 frame motor at 4,000 rpm weighs approximately 850 kg and produces 500 kW. The same frame at 5,000 rpm produces 625 kW. If the application needs 500 kW, the motor can drop to an IEC 315 frame at 5,000 rpm — weighing approximately 650 kg. Weight saving: 200 kg. On a crane head where every kilogram affects the boom structural design and the counterweight requirement, this saving translates to structural cost reductions far exceeding the motor price difference.

Modern VFDs (variable-frequency drives) produce better torque control and higher efficiency at higher motor speeds. At 5,000 rpm, the motor operates further from the low-frequency torque derate zone where current-limited drives lose controllability. The ZL95 allows the winch system to be designed with the motor running at 3,000-5,000 rpm for the primary hoisting duty and de-stroking to 500-1,500 rpm for precision positioning — keeping the motor in its efficient operating band throughout. Contact Korea Ever-Power for motor-gearbox pairing recommendations at 5,000 rpm.

Where Ratio 4,800 Still Helps

Applications where the motor must maintain efficient mid-speed operation while the drum barely moves: deep borehole logging at 5,000+ metres where the wireline speed must be held constant at 0.5-1.0 m/min for the entire descent. At ratio 4,800, the motor runs at 2,400-4,800 rpm for this line speed — firmly in the efficient torque band. At ratio 2,000, the motor would need to run at 1,000-2,000 rpm — closer to the low-speed derate zone where torque ripple and thermal limits degrade the cable speed consistency.

Where Higher Ratios Stop Helping

At ratio 4,800, the encoder resolution through the gearbox produces cable position increments of 20 microns or less. But the wire rope stretches 0.1-0.5% under load — which at 5,000 metres of deployed cable is 5-25 metres of elastic elongation. The position uncertainty from cable stretch is 100,000 times larger than the encoder resolution. Beyond ratio 4,800, increasing the ratio improves the theoretical gearbox resolution without improving the practical cable position accuracy. The cable, not the gearbox, is the precision bottleneck.

Heavy Electric Cranes With High-Speed Motors (60-100 t)

The ZL95 at ratio 80-200, 2-3 stage, paired with 500-900 kW high-speed PMSM motors at 5,000 rpm serves the 60-100 tonne electric crane class with motors one IEC frame smaller than the equivalent 4,000 rpm configuration. For offshore construction vessel cranes where the crane head weight directly affects the vessel stability, the motor downsizing translates to a lighter crane that can lift heavier cargo. The slewing drive En wheel drive complete the all-electric crane system.

Electric Mining Main Production Hoists

Main production winders at mines with shaft depths of 400-800 metres where the sustained drum torque stays within the ZL95 115,000 Nm continuous limit. The 5,000 rpm input allows a compact high-speed AC motor (500-800 kW, IEC 315-355 frame) to replace the larger, heavier motor frame that 4,000 rpm demanded — reducing the headframe winder house footprint and the structural load on the headframe. Regen recovery during skip descent returns 20-35% of the hoist energy to the mine grid.

Deep Borehole and Wireline Winches

Wireline logging winches for oil and gas well logging, geothermal exploration, and deep scientific drilling at depths of 3,000-8,000 metres. The ZL95 at ratio 2,000-4,800 (4-5 stage) maintains constant wireline speed (0.5-2 m/min) through the entire well depth with the motor running at efficient mid-speed (2,500-5,000 rpm). The 115,000 Nm continuous handles the combined tool string and cable weight at the deepest logging points. The DIN 5-6 gear accuracy ensures the depth encoder signal remains reliable through the full borehole depth.

What enables the ZL95 to accept 5,000 rpm when the ZL85 caps at 4,000?

The ZL95 input bearing arrangement uses a precision angular-contact bearing pair instead of the single deep-groove bearing used in the ZL30-ZL85 input design. The angular-contact pair handles the combined axial and radial loads at 5,000 rpm with adequate speed margin and L10 life. The first-stage sun gear tooth profile is also modified with a deeper crowning that reduces the contact stress concentration at the higher tooth peripheral velocity. These changes add approximately 5-8% to the manufacturing cost but enable the 25% input speed increase that drives the motor downsizing advantage.

Can the ZL95 run at 4,000 rpm or below with standard motors?

Yes. The 5,000 rpm is a maximum, not a requirement. Any motor producing up to 5,000 rpm can drive the ZL95 — including the 1,500 rpm and 3,000 rpm motors commonly used in industrial applications. The 5,000 rpm capability is an option that the winch designer can utilise if the motor selection benefits from higher speed. If the application uses a standard 3,000 rpm motor, the ZL95 operates identically to the ZL85 at the same speed — with 31% more torque capacity.

How much motor weight does the 5,000 rpm capability actually save?

For the same shaft power: approximately 15-25% motor weight reduction. A 600 kW motor at 3,000 rpm (IEC 400 frame): approximately 1,100 kg. The same 600 kW at 5,000 rpm (compact high-speed frame): approximately 800-950 kg. Saving: 150-300 kg. For a crane where the motor sits on the crane head, this weight saving is multiplied by the boom ratio — 200 kg at the crane head saves 600-1,000 kg of counterweight at the rear. The total crane structural benefit exceeds the motor weight saving by 3-5x.

Does the higher input speed increase gearbox noise?

At the same output speed and torque: no. The gearbox noise is dominated by the output-stage gear mesh, which operates at the same speed regardless of whether the input is 4,000 or 5,000 rpm (the input speed is reduced through the ratio to the same output speed). At the input stage, the higher speed produces a slightly higher-pitched noise component, but the amplitude is lower because the input-stage torque is lower (same power at higher speed = lower torque per tooth). The net effect is typically within 1-2 dB(A) of the 4,000 rpm noise level — imperceptible in practice.

How does the ZL95 compare to the 4xxW 414W3 mega-class at overlapping torque?

The 414W3 delivers 140,000 Nm continuous at FEM M6 with -40 deg C Arctic rating and 1,250 kg. The ZL95 delivers 115,000 Nm continuous with 245,000 Nm peak. For applications needing 115,000-140,000 Nm sustained (mining production, AHTS), the 414W3 is the stronger choice because its continuous capacity exceeds the ZL95. For applications where the sustained torque stays below 115,000 Nm and the transient peaks reach up to 245,000 Nm (electric cranes, marine winches), the ZL95 provides higher peak capacity, regen braking, quieter operation, and motor downsizing — at a fraction of the 414W3 weight.

What is the thermal power at 5,000 rpm versus 4,000 rpm?

The Pt rating (26-90 kW depending on stage count) is independent of the input speed — it is determined by the housing surface area and the oil-bath convection capacity, neither of which changes with input speed. However, the heat generated inside the gearbox is proportional to the power throughput, which is proportional to speed x torque. At 5,000 rpm at the same output speed and torque, the power throughput is the same as at 4,000 rpm — the input speed is higher but the input torque is proportionally lower. The thermal behaviour at 5,000 rpm is therefore identical to 4,000 rpm for the same output duty. Contact Korea Ever-Power for a thermal analysis at your specific motor speed and duty cycle.

80 t all-electric offshore crane, ZL95 at ratio 100, 2-stage, 750 kW PMSM at 4,800 rpm. The high-speed motor is an IEC 315 frame — one size smaller than the IEC 355 we would have needed at 3,600 rpm. Weight saving: 220 kg at the crane head. The naval architect used this saving to extend the boom by 1.5 metres, increasing the crane working radius by 8% without adding counterweight. The ZL95 245,000 Nm peak handled the classification society proof-load test (100 t at 1.25x) without any overcurrent trip. After 6 months of vessel operation, the VFD data log shows the motor has never exceeded 4,600 rpm during normal crane duty — the 5,000 rpm headroom is available but not routinely needed.

Wireline logging winch for a 6,500-metre geothermal exploration well. ZL95 at ratio 3,500, 5-stage, 40 kW servo motor at 5,000 rpm. The winch maintains 1.0 m/min wireline speed through the entire well depth — the motor runs at 3,500-4,200 rpm in its efficient band while the drum barely turns. Depth accuracy verified by magnetic mark counting on the wireline: within 0.3% of the total depth at 6,500 m (approximately 19.5 metres cumulative error). The previous winch system (hydraulic, lower ratio) required the motor to crawl at 200 rpm to achieve the same wireline speed — causing torque ripple that produced 2-3% depth error at the same well depth. The ZL95 high ratio eliminated the motor-speed-related depth error entirely.

Main production winder at a 580-metre copper-gold mine, ZL95 at ratio 350, 4-stage, 600 kW AC motor at 4,500 rpm. The 5,000 rpm capability allowed us to specify an IEC 315 frame motor (720 kg) instead of the IEC 355 (950 kg) we had budgeted. The 230 kg saving simplified the headframe crane installation and reduced the winder bed foundation load. Regen recovery: 26% of the hoist energy, measured at 22 kWh per cycle for a 15-tonne skip from 580 m. The 4-star reflects a VFD compatibility note: our existing VFD switching frequency was set for 4,000 rpm maximum. Running the motor at 4,500 rpm required a firmware update and a higher switching frequency that slightly increased the VFD audible noise at the control cabinet — resolved by adding a line reactor, but it would have been caught earlier if the ZL95 data sheet had included a VFD minimum switching frequency recommendation for operation above 4,000 rpm.