ZL24 Wheel Drive Planetary Gearbox

The vehicle uses a diesel engine driving hydraulic pumps. The integrated brake is a regulatory or operational requirement. The machine will never be electrified. The existing fleet is standardised on the 6xx series and cross-compatibility with spare parts matters more than performance optimisation.

The vehicle uses battery-electric or hybrid-electric propulsion. Regenerative braking is part of the energy management strategy. Low noise matters (underground mining, port terminals near residential areas). The motor speed exceeds 3,000 rpm. The application needs ratios below 33 or above 142 (outside the 6xx range).

The first generation of battery-electric mining haul trucks (30-50 tonne payload) uses 150-300 kW PMSM motors at 2,500-4,000 rpm. The ZL24 2-stage at ratio 20-40 converts this motor output into 21,000 Nm of sustained wheel torque for loaded haul road climbing. The helical gear mesh reduces drivetrain noise by 8-12 dB compared to a hydraulic-era straight-cut wheel drive — a critical factor in electric vehicles where the absence of engine noise makes gearbox mesh audible to the operator.

When a loaded electric truck descends a haul road, the motor operates as a generator, feeding energy back through the ZL24 gearbox to the battery. The ZL24 transmits this reverse-direction torque at the same rated capacity as forward drive — the helical planetary gear train is mechanically symmetrical. On a typical open-pit mine cycle with a 15% loaded downhill return, regen recovers 15-25% of the energy consumed during the loaded uphill climb, directly extending battery range and reducing the required charging infrastructure.

Battery-electric terminal tractors, straddle carriers, and reach stackers replacing diesel-hydraulic predecessors in ports with zero-emission mandates. The ZL24 1-stage at ratio 4-8 paired with a high-torque PMSM motor provides the 15-25 km/h travel speed these machines need for productive container throughput, with the full 21,000 Nm available for loaded breakaway on wet, polished terminal apron surfaces. The absence of an internal brake eliminates interference with the electric motor regen braking algorithm.

Autonomous trucks and heavy vehicle platforms requiring precise speed control at the wheel for path-following accuracy. The DIN 5-6 gear accuracy of the ZL24 preserves the PMSM motor encoder resolution through the gear reduction, enabling the autonomous controller to command wheel speed with sub-percentage precision. Contact Korea Ever-Power for the position resolution and backlash specification at your target ratio.

Battery-Electric Haul Trucks (30-50 t)

First-generation BEV mining trucks replacing diesel-hydraulic predecessors on haul roads with grades up to 15-20%. The ZL24 2-stage at ratio 25-40 paired with a 200 kW PMSM motor provides the sustained climbing torque and the regen braking capacity for the descent cycle. The helical gears eliminate the characteristic straight-cut gear whine that would otherwise be the dominant noise source on an electric truck operating without engine masking noise.

Electric Port Terminal Equipment

Battery-electric and hybrid-electric straddle carriers, terminal tractors, and reach stackers operating under port zero-emission mandates. The ZL24 1-stage at ratio 4-8 provides the high-speed, high-torque combination that container handling demands, while the 50,500 Nm peak accommodates the loaded breakaway torque spikes that occur when pulling a 40-tonne container from a standing start on a wet surface. The slewing drive planetary gearbox handles the spreader rotation on the same platform.

Autonomous Underground Mining Vehicles

Battery-electric autonomous LHDs (load-haul-dump) and personnel carriers for underground mines transitioning away from diesel for ventilation cost reduction. The ZL24 3-stage at ratio 60-120 provides the traction for steep ramp grades in underground drifts, and the reduced noise (helical gears + no diesel engine) significantly improves the working environment for any human operators sharing the drift. The track drive planetary gearbox serves the tracked underground dozer variants in the same fleet.

Why is the ZL24 input speed 4,000 rpm instead of 5,200 like the ZL02?

The ZL24 gears are physically much larger than the ZL02 to carry 14x the torque. Larger gears at the same rotational speed produce higher tooth peripheral velocity — the speed at which the gear teeth slide past each other. Above a critical peripheral velocity, the lubricant film between the teeth breaks down, causing scuffing and accelerated wear. The 4,000 rpm limit ensures the ZL24 tooth peripheral velocity stays within the safe operating envelope for 20CrMnTi carburised steel at the gear module sizes used in this frame. This limit is still 33% higher than the 6xx series (3,000 rpm), which is the margin that electric motor compatibility requires.

Can the ZL24 replace a 609 on an existing diesel-hydraulic truck converting to electric?

Not as a drop-in replacement. The ZL24 and 609 have different housing dimensions, output flange patterns, and input interfaces. A diesel-to-electric conversion requires redesigning the wheel-end mounting structure to accommodate the ZL24 housing geometry. However, the output flange bolt circle follows SAE standards, so the wheel rim interface may be compatible if the BCD matches. Contact Korea Ever-Power with the existing 609 dimensional drawing and the proposed electric motor specifications for a conversion feasibility assessment.

How does the ZL24 handle the thermal load from continuous regen braking on a long downhill grade?

During regenerative braking, the gearbox dissipates heat proportional to (1 - efficiency) multiplied by the regen power flow. At 94% efficiency and 100 kW regen power, the gearbox absorbs 6 kW of heat — the same as during 100 kW forward drive. The 15-46 kW thermal power rating (Pt) of the ZL24 is designed for continuous forward drive plus continuous regen in a balanced duty cycle. On sustained downhill grades exceeding 3 km, verify that the total thermal load (forward + regen averaged over the cycle) does not exceed the Pt rating for the selected stage count.

What noise level does the ZL24 produce compared to a 6xx-series wheel drive at the same torque?

The helical gear mesh of the ZL24 produces approximately 8-12 dB(A) less noise than the straight-cut gears used in the 6xx series at equivalent speed and torque. At 2,000 rpm input under full load, the ZL24 2-stage typically measures 68-72 dB(A) at 1 metre versus 78-82 dB(A) for a comparable 6xx model. On a diesel truck, this difference is masked by engine noise. On a battery-electric truck with no engine, the wheel drive gearbox becomes the primary noise source — making the 10+ dB advantage of helical gears the difference between operator comfort compliance and failure.

What motor power class pairs with the ZL24 for a 40-tonne electric mining truck?

A 40-tonne payload truck at 80-tonne GVW climbing a 15% grade at 10 km/h requires approximately 130 kW of sustained propulsion power per axle (2 wheel drives). Each ZL24 receives approximately 65 kW. At ratio 30 and 3,500 rpm motor speed, the motor output torque is 21,000 / 30 = 700 Nm at the motor shaft. A 65 kW, 700 Nm, 3,500 rpm PMSM motor (approximately 200 mm diameter, 300 mm length, 80-100 kg) is a standard industrial servo motor frame size — compact, readily available, and well within the ZL24 input speed envelope.

What is the expected service life of the ZL24 in an electric vehicle application?

The 100,000-hour rated life at continuous torque translates to approximately 11 years of 24/7 operation. In practice, electric vehicle duty cycles are less severe than diesel-hydraulic equivalents because regen braking reduces the net mechanical energy throughput per tonne-kilometre. The ZL24 in an electric mining truck is expected to outlast the first battery pack (typically 5,000-8,000 hours) by a factor of 10-15x. The gearbox is a fit-and-forget component — the vehicle battery, power electronics, and tyres will all reach their service limits before the ZL24 requires its first overhaul.

Prototype BEV haul truck, 35-tonne payload, ZL24**2 ratio 32, paired with 180 kW PMSM motors. The truck completed our full certification test programme including the 18% loaded grade climb, 5 km sustained downhill regen descent, and -28 deg C cold-start test. Noise measurement inside the cab during the grade climb was 64 dB(A) — 18 dB lower than our diesel-hydraulic baseline truck. The regen energy recovery on the 5 km descent was 22% of the energy consumed during the loaded ascent, exactly matching our simulation model. We have committed to 8 trucks for the initial production run with ZL24 as the standardised wheel drive.

Electric straddle carrier conversion, ZL24**1 ratio 6, replacing a diesel-hydraulic 609 drivetrain. The conversion required a new wheel-end mounting bracket (the ZL24 housing is a different shape to the 609) but the wheel rim bolt circle was compatible. Result: 30% reduction in energy cost per container move, zero tailpipe emissions, and the operators immediately noticed how quiet the machine is at creep speed during container stacking. The regen braking recovers enough energy during each loaded deceleration to offset approximately 12% of total consumption. The ZL24 has been in service for 11 months on a 16-hour-per-day cycle with zero maintenance beyond the scheduled oil change.

Autonomous electric LHD, 12-tonne payload, ZL24**3 ratio 80, 75 kW induction motor. The machine operates autonomously in a gold mine, 800 metres below surface, on a 12% ramp between the stope and the ore pass. The ZL24 noise level underground is dramatically lower than the diesel LHD it replaced — the ventilation fans are now the loudest thing in the drift, which is exactly the outcome our ventilation engineers wanted. The 4-star rating reflects one integration challenge: the ZL24 data sheet did not specify the exact moment of inertia of the internal gear train, which our motor controller engineer needed to tune the regen braking algorithm precisely. We estimated it, tuned iteratively, and achieved good results — but having the MOI value published for each stage configuration would have saved two weeks of commissioning time.