Wheel Drive Series — Port & Logistics Equipment
フォークリフト用ホイール駆動式遊星歯車減速機
From 2-tonne electric reach trucks navigating narrow warehouse aisles to 46-tonne heavy-duty counterbalance forklifts handling steel coils at port terminals, the wheel drive planetary gearbox is the mechanical heart of every driven axle — delivering maximum torque in minimum space while enduring decades of continuous operation.
The forklift industry spans an extraordinary range of machine classes, duty cycles, and operating environments — yet every driven axle shares the same fundamental requirement: a gearbox that multiplies motor torque to the driven wheel with the highest possible power density, the smallest possible installation envelope, and a service life measured in decades rather than years. The hub-mount planetary architecture — with co-axial input and output, multi-planet torque sharing, and integrated flange — has replaced conventional bevel-differential axle drives across the global forklift industry. Korea Ever-Power supplies units covering output torques from 700 Nm (compact walkie reach trucks) through 280,000 Nm (46-tonne container handler drive axles), engineered to the dimensional standards required by major OEM and aftermarket applications worldwide.
Forklift Classes and Drive Requirements: A Complete Spectrum
Class 1 — Electric Counterbalance Forklifts (1–10 t): The dominant segment by unit volume, comprising three-wheel and four-wheel electric forklifts in warehouses, distribution centres, and manufacturing facilities. Drive axle output torque requirements range from 8,000 Nm (1 t three-wheel) to 65,000 Nm (10 t four-wheel). Compact axle width is critical — warehouses standardise aisle widths that penalise unnecessary gearbox width. Electric motor integration via IEC B5 flange input is the universal standard for this class.
Class 2 — Electric Narrow Aisle Trucks (1–3 t): Reach trucks, turret trucks, and very narrow aisle order pickers operating in racking systems with aisles as narrow as 1,650 mm. The driven traction wheel in a reach truck is a single rear-centre wheel, imposing extreme packaging demands. Hub-mount planetary drives with ratios of 25:1 to 40:1 and integrated SAHR parking brakes are the standard specification for this class.
Class 3 — Electric Walkie and Rider Pallet Trucks: High-volume floor-level movers where the gearbox must fit within the traction wheel itself — output torques of 2,000 to 6,000 Nm and overall diameters constrained to 200–320 mm. Ultra-compact two-stage planetary designs with aluminium alloy carriers dominate this class.
Class 4 and 5 — IC Counterbalance Forklifts (1–46 t): Diesel and LPG forklifts in yards, ports, timber handling, steel service centres, and heavy manufacturing. The torque range extends from 12,000 Nm (1 t IC) to 280,000 Nm (46 t heavy-duty counterbalance). These machines require IP67-rated floating face seals and corrosion protection for the port environment. Travel speeds of 25–30 km/h combined with high torque require carefully optimised gear ratios — typically 18:1 to 35:1 — matching motor speeds to the efficiency peak of diesel-hydraulic or hydrostatic drive systems.
Korea Ever-Power Range — Forklift Selection Guide
Korea Ever-Power hub-mount planetary drives cover all forklift classes. The ZL01 and ZL02 serve light electric trucks from 700 Nm; the ZL24 and heavy EP-WD series handle port-terminal counterbalance axles up to 280,000 Nm. All models available with IEC B5 or SAE flange input, with or without integrated SAHR parking brake.
| モデル | 出力トルク | 比率 | Forklift Capacity | シール |
|---|---|---|---|---|
| ZL01 | 700 – 1,500 Nm | 3.48 – 2,702 | Walkie / 1–1.5 t electric | IP65 |
| ZL02 | 1,500 – 3,000 Nm | 3.48 – 2,702 | Electric 2–3.5 t | IP65 |
| 611L2/L3 | 8,000 – 28,000 Nm | 18 – 35 | 4 – 7 t | IP67 |
| ZL24 | 21,000 – 50,500 Nm | 4 – 2,319 | 8 – 25 t heavy IC | IP67 |
| EP-WD-280 | 280,000 Nm | 10 – 22 | 46 t container handler | IP67 FKM |
Planetary Architecture: Four Structural Advantages Over Conventional Axles
The transition from conventional bevel-gear differential axles to independent hub-mount planetary drives took place through the 1990s and 2000s, driven by four structural advantages that conventional axles cannot match:
⚙ Torque Sharing Across Multiple Planets
A three-planet carrier distributes input torque across three simultaneous load paths, each transmitting one-third of total torque. This reduces individual gear tooth loading by 66% compared to a single-mesh drive, enabling dramatically higher power density within the same gear module and centre distance. A 280,000 Nm output hub-mount unit that fits within a 620 mm wheel diameter would require a gearbox three to four times larger using conventional parallel-shaft geometry.
🔄 Co-Axial Input and Output
The co-axial geometry allows the drive motor to mount directly on the inboard face of the gearbox while the outboard flange mounts to the wheel hub. This eliminates the 90-degree bevel drive that conventional axles require, removing both the power loss and the packaging penalty of that bevel stage — typically saving 80 to 140 mm of axle width per driven wheel.
🚫 Independent Left-Right Control
Independent wheel drive — one motor and gearbox per driven wheel — enables electronic differential control far exceeding mechanical open or limited-slip differentials. Electric forklift traction controllers apply precise torque independently to each driven wheel, providing active yaw damping, anti-slip traction control, and regenerative braking coordination that are impossible with a shared mechanical differential.
🛠 Sealed-for-Life Output Bearing
Modern hub-mount planetary drives use tapered roller bearings on the main output bearing, grease-lubricated and sealed for life. This eliminates the periodic wheel bearing regreasing that added significant maintenance cost to conventional beam-axle forklifts. The tapered roller design simultaneously supports the radial load from tyre weight and the axial loads generated during cornering at speed.
Sealing Systems: Warehouse IP65 vs Port-Duty IP67 Floating Face Seal
The most critical specification decision in hub-mount drive selection is seal type — the operating environment determines whether a standard radial lip seal provides adequate protection or whether a full floating face seal is mandatory.
Radial lip seals (IP65) suit indoor warehouse forklifts on clean, dry concrete. A nitrile rubber lip seal running on a hardened shaft lasts 3,000 to 5,000 hours in clean indoor service. For Class 1 and Class 2 electric forklifts in food distribution, pharmaceutical, or light manufacturing warehouses, the radial lip seal is the cost-effective standard.
Floating face seals (IP67) are mandatory for outdoor operation: construction yards, timber handling, steel service centres, ports, or any environment where the wheel runs through water, mud, sand, or abrasive fines. The floating metal cassette seal maintains contact pressure through a spring mechanism regardless of shaft deflection — a positive metal-on-metal primary seal backed by an elastomer secondary. These seals withstand sustained immersion to one metre water depth, pressure washing at 100 bar, and the continuous abrasive ingress that destroys radial lip seals within 500 hours in port terminal service.
All Korea Ever-Power units above 7 tonne capacity are supplied with the floating face seal as standard. Lighter units are available in either seal standard to match the operating environment. For port-duty equipment also including reach stackers and RTG cranes, see our related heavy-duty wheel drive range.
Electric Forklift Integration: Motor Flange, Encoder, and Thermal Management
The electrification of the forklift industry — accelerating through the 2020s with lithium-ion battery adoption — places new demands on hub-mount drives beyond torque and speed. Three integration requirements are now standard for electric forklift OEM supply:
IEC B5 Flange Integration: All electric forklift traction motors use IEC B5 flange-mount configuration, and the wheel drive gearbox must mate directly to the motor flange without an intermediate coupling. Korea Ever-Power WD units are supplied with machined IEC B5 input flanges — available for motor frames IEC 100 through IEC 200 — with pilot spigot fits and bolt circle dimensions conforming to IEC 72-1. Eliminating the intermediate coupling reduces total drivetrain length, removes a potential failure point, and improves torque transmission efficiency by 1.5 to 2.5 percentage points.
Integrated Speed Sensor Mounting: Modern traction controllers require wheel speed feedback for regenerative braking coordination, electronic differential control, and anti-slip management. Korea Ever-Power WD units are available with pre-machined sensor mounting provisions on the input flange, eliminating custom brackets that add cost and vibration-induced failures to aftermarket sensor installations.
Oil Temperature Management: High-intensity 24-hour duty cycles with frequent starts, stops, and regenerative braking can raise gearbox oil temperatures above the 90°C threshold where viscosity breakdown accelerates bearing wear. Units above 28,000 Nm output are available with integrated oil temperature sensor ports and optional external cooling circuit connections.
Heavy Counterbalance Forklifts in Port Terminals: Maximum Torque, Maximum Durability
Port terminal heavy counterbalance forklifts — handling intermodal containers, steel coils, timber packs, and break-bulk cargo at capacities from 16 to 46 tonnes — represent the most demanding hub-mount drive application in any operating environment. Three factors combine to impose exceptional stress on the gearbox:
Maximum Dynamic Load from Load Radius: A 46-tonne rated counterbalance forklift may impose 80 to 120 tonnes of total vertical load on the rear driven axle during rated lift operations. This static load is further amplified by a dynamic factor of 1.3 to 1.6 during travel on uneven terminal surfaces — concrete blocks, bridge plates, ramp transitions — generating peak wheel loads of 130 to 190 tonnes. The main output bearing must carry this load for 5,000 to 8,000 hours between planned overhauls.
Marine Corrosion Environment: Port terminals expose all equipment to salt air, condensation, and intermittent water exposure more aggressive than inland industrial environments. Korea Ever-Power port-duty units use fluoroelastomer secondary seals on all cassette seal assemblies and a two-coat epoxy primer plus polyurethane topcoat rated to 2,500 hours salt spray per ISO 9227.
Shock Loading from Container Handling: Peak shock torque events during container-down operations can reach 3.0 to 3.5 times rated torque, imposed in millisecond-duration impulses. Port-duty units use case-hardened and shot-peened gear teeth — carburising depth 1.2 to 1.8 mm, surface hardness 58 to 62 HRC — with a compressive residual stress layer that significantly extends fatigue life.
Integrated SAHR Parking Brake: Design, Certification, and Application
The spring-applied, hydraulically-released multi-disc parking brake integrated into the hub-mount gearbox is a fundamental safety component in all forklifts above 5 tonnes capacity. The SAHR brake is fail-safe by design: spring force applies the brake whenever hydraulic pressure is absent — during an emergency stop, a hydraulic system failure, or when the forklift is parked. Only an active hydraulic signal releases the brake for travel.
Korea Ever-Power integrates the SAHR brake as a modular assembly on the inboard face of the WD gearbox housing, between the motor mount flange and the first planetary stage. This positioning — on the input side of the reduction — allows the brake to operate at motor speed rather than wheel speed, dramatically reducing the brake torque requirement and enabling a compact multi-disc package to generate the stopping force required for the rated gross vehicle weight on a 15% grade.
Disc wear is measurable externally through inspection ports without disassembly, and the disc pack can be replaced as a cartridge unit without removing the gearbox from the machine. All SAHR brake packages are certified to meet the slope-holding requirements specified in EN ISO 3691-1 and EN 1459 at the rated gross vehicle mass of the machine for which the package is specified.
Field Failure Analysis: Common Wheel Drive Failures and Prevention
| Failure Mode | Primary Cause | Warning Signs | Prevention |
|---|---|---|---|
| Seal failure — oil loss | Abrasive ingress cutting lip seal; wrong seal type for environment | Oil film on wheel rim; reduced oil level at inspection | Match seal type to environment; inspect at 500 h intervals |
| Planet bearing fatigue | Lubrication starvation from overextended oil change interval | Elevated noise at specific speeds; metallic particles in oil sample | Change oil at 1,000 h; use oil analysis to find early wear |
| Sun gear pitting | Sustained operation above rated torque — overloaded truck | Vibration at low speed; fine metallic particles in oil | Enforce load limits; fit traction controller torque limiters |
| Main output bearing failure | Overload or incorrect bearing preload at rebuild | Wheel play detectable by hand; heat at hub during travel | Check preload at 2,000 h; use factory rebuild specification |
| SAHR brake drag | Worn brake discs exceeding retraction clearance; blocked release port | Heat at hub during travel; increased power consumption | Check disc wear at 2,000 h; keep hydraulic release port clean |
| Ring gear fracture | Repeated shock overload in container-handling duty; inadequate case depth | Sudden noise followed by loss of drive | Specify port-duty variant with shot-peened gears; fit torque limiter |
Selection Parameters: What Our Engineers Need to Size Your Drive
Providing complete data at initial enquiry enables our engineers to deliver a dimensionally verified specification within 48 hours. For aftermarket replacement of a hub-mount planetary wheel drive from any manufacturer, the existing unit label data is usually sufficient to identify a compatible replacement.
📑 Machine Parameters
Rated lift capacity (t), gross vehicle weight (t), rated travel speed (km/h), wheel diameter and tyre size, number of driven wheels, duty cycle
⎈ Motor Data
Motor type (hydraulic / AC / DC), rated torque (Nm), rated speed (rpm), output flange standard (IEC frame or SAE), shaft diameter and keyway
🌟 Environment
Indoor / outdoor, surface type, salt air exposure, wash-down frequency, ambient temperature range (°C)
🔧 Mounting Interfaces
Hub bolt circle PCD and bolt count, hub bore diameter, axle width constraint, SAHR brake requirement, parking hold grade (%)
Related Drive Solutions from Korea Ever-Power
🚚 AGV and AMR Wheel Drives
The ZL01 and ZL02 series — the same units serving walkie trucks — are widely specified for automated guided vehicles and autonomous mobile robots in high-bay warehouses. Their compact envelope, low-backlash planetary stage, and compatibility with encoder-equipped servo motors make them the preferred choice for AGV traction drive integrators.
⚓ Reach Stacker and RTG Drives
Reach stackers and rubber-tyred gantry cranes traversing container yard blocks use high-torque hub-mount drives sharing the same ZL24 and EP-WD platform as heavy IC forklifts, with marine-grade corrosion protection and FKM seal upgrades appropriate for open-air port terminal operation year-round.
🕜 Track Drive for Crawler Equipment
For tracked port handling equipment, Korea Ever-Power offers the complementary トラック駆動遊星歯車機構 series — same manufacturing standards, compatible documentation, and unified spare parts logistics for multi-equipment port fleets.
Why Forklift OEMs and Fleet Operators Choose Korea Ever-Power
20+
Years supplying hub-mount planetary drives to forklift OEMs and fleet aftermarket across 40+ export markets
2 – 46 t
Full capacity coverage — a single supplier for all forklift classes from walkie pallet trucks through 46-tonne heavy IC container handlers
48 h
Dimensional drawing and verified specification turnaround for OEM or aftermarket replacement enquiries, including custom gear ratios
ISO 9001
Certified quality management system; every production gearbox undergoes load testing and oil leak verification before shipment
Korea Ever-Power operates its own gear manufacturing facility — carburising furnaces, CNC gear hobbing, gear grinding, and co-ordinate measuring machines are all in-house. This vertical integration eliminates the quality variability introduced when outsourcing gear-cutting to sub-suppliers, and gives our engineering team direct control over the case depth profiles, tooth geometry tolerances, and surface finish specifications that determine the field service life of every gearbox we supply.
Our aftermarket support model is built around the same engineering data that drives OEM supply. When a fleet operator needs to replace a wheel drive unit from a competitor brand, we size our unit to the same mounting interfaces using the existing vehicle parameters — no machine modification required. Dimensional drawings, oil fill specifications, and SAHR brake hydraulic circuit data are provided with every shipment. For OEM programmes requiring volume supply, we offer blanket order agreements with call-off lead times as short as 5 working days from confirmed stock.
Source Your Forklift Wheel Drive Planetary Gearbox
Whether you need a compact hub-mount unit for a 2-tonne electric reach truck, a heavy-duty port-terminal unit for a 46-tonne container handler, or a complete OEM supply programme — Korea Ever-Power has the engineering team and manufacturing capacity to deliver. Browse our full wheel drive range or send us your machine parameters for a free application review.
Edit by Cxm
