603L2A Planetary Wheel Drive Gearbox Reducer — 2-Stage

603L2A — Four Ratios, One Housing, Zero Compromise

The jump from a single-stage to a two-stage planetary wheel drive gearbox is not simply about more torque. It is about giving the vehicle designer a set of gear ratios that span the gap between highway-speed roading and low-speed, high-traction earthmoving — all within the same wheel hub envelope. The EP-603L2A does this with four discrete ratios (19, 23, 32, and 40) that cover a 2:1 speed-to-torque trade-off range, matching the requirements of mid-weight wheeled machines from 5 to 8 tonnes.

At 4,000 Nm maximum output torque and 3,000 rpm input speed, the 603L2A accepts both high-speed axial piston motors for variable-displacement hydrostatic circuits and fixed-displacement gear motors for simpler open-loop systems. The integral 210 Nm parking brake and manual declutch carry forward from the 601 series, maintaining the field-serviceability and towing safety that operators expect from a professional-grade wheel drive.

A planetary wheel drive gearbox bolts directly to the wheel rim — there are no axle shafts, no hubs, no intermediate bearings between the gearbox output flange and the tyre. This means the bolt circle diameter (BCD), stud size, centering spigot diameter, and flange offset must match between the gearbox and the rim to within tenths of a millimetre. A mismatch in any of these dimensions creates either a drive that cannot be assembled or, worse, one that assembles but concentrates load on a subset of the bolts.

Telehandlers and Rough-Terrain Forklifts

Telehandlers in the 6-8 tonne class need both the speed to road between job sites at 20+ km/h and the traction to climb loaded ramps at 15-25% gradient. The 603L2A at ratio 23 is the sweet spot for most telehandler applications: fast enough for productive site transit, geared low enough to handle typical construction site grades without stalling the hydrostatic circuit. The 3,000 rpm input speed matches the common 63-80 cc/rev axial piston motors used in telehandler hydrostatic transmissions.

Backhoe Loaders and Compact Wheel Excavators

Backhoe loaders spend roughly equal time travelling between dig locations and working at the trench. The 603L2A at ratio 19 maximises roading speed for machines that cover long distances on paved roads between sites, while ratio 32 suits machines that work predominantly off-road on soft soils. Many OEMs offer the same backhoe model with two wheel drive ratio options — one for road-heavy utility work and one for off-road earthmoving — using the same 603L2A housing.

Agricultural Sprayers and Self-Propelled Harvesters

Self-propelled crop sprayers and small harvesters require controlled low-speed field travel (5-12 km/h) with precise speed regulation from the hydrostatic wheel drive system. The 603L2A at ratio 40 delivers this speed range at motor speeds of 1,000-2,500 rpm, keeping the hydrostatic pump and motor in their most efficient operating band. The sealed oil-bath housing prevents crop chemical and fertiliser contact with the gear set — a common failure mode with chain-drive alternatives in agricultural applications.

Why is the 603L2A brake torque (210 Nm) lower than the 601L1A (450-600 Nm)?

The 210 Nm brake on the 603L2A is an input-side brake that acts through the gear ratio. Its effective holding torque at the wheel is 210 Nm multiplied by the gear ratio — for example, 210 x 23 = 4,830 Nm at ratio 23, or 210 x 40 = 8,400 Nm at ratio 40. This is substantially higher than the 601L1A output-side brake. The input-side placement reduces the brake disc diameter and weight, which is important at 85 kg total unit weight. The trade-off is that the brake cannot hold if the gearbox internal gears are damaged — in that unlikely event, the vehicle requires external wheel chocks.

Can I change the gear ratio in the field, or is it fixed at the factory?

The ratio is fixed at the factory. The sun gears and ring gears are matched sets that determine the ratio; swapping them requires complete disassembly, precision measurement, and re-assembly with the correct bearing preload. It is not a field-changeable parameter. If your vehicle platform needs to offer two speed ranges (for example, ratio 19 for road models and ratio 32 for off-road models), order both variants separately and install the appropriate one during vehicle assembly.

What size hydraulic motor pairs best with the 603L2A wheel drive?

That depends on the target ground speed and the available hydraulic flow. For a machine requiring 20 km/h at ratio 23 with a 500 mm tyre: the required output speed is 106 rpm, so the motor speed is 106 x 23 = 2,438 rpm. If your pump delivers 100 L/min, the motor displacement should be approximately 100,000 / 2,438 = 41 cc/rev. Common pairings are 45-80 cc/rev variable-displacement motors at 200-350 bar, driven by load-sensing pumps. Contact Korea Ever-Power with your pump flow and target speed for a verified motor-gearbox match.

How does a two-stage planetary wheel drive compare to a hub reduction axle?

A conventional hub reduction axle uses a central differential, half-shafts, and a planetary hub reducer at each wheel. The total system weight is typically 2-3 times higher than a pair of wheel drive gearboxes for the same torque class, and the differential introduces a mechanical complexity (limited-slip or locking mechanism) that the independent hydrostatic wheel drive eliminates entirely. Each wheel drive is independently controlled through its own hydraulic motor, giving the vehicle inherent differential steering capability without any mechanical differential. The trade-off is that the hydrostatic system must be designed to handle the full flow for independent wheel speed control, which increases the hydraulic component cost compared to a single-pump axle drive.

Is the 603L2A wheel drive gearbox suitable for road-registered vehicles?

Yes, in jurisdictions that permit hydrostatic-drive vehicles on public roads (most countries allow this for agricultural and construction vehicles under 40 km/h). At ratio 19, the 603L2A achieves 25+ km/h ground speed which meets the minimum travel speed requirements for most road registrations. The parking brake satisfies the requirement for an independent holding brake on gradients. Verify local regulations for braking performance, lighting, and speed limiter requirements specific to your vehicle class and region.

What is the difference between the 603L2A and the 603L2B wheel drive gearbox reducer variant?

The 603L2A and 603L2B share the same 4,000 Nm torque rating, the same four ratios (19, 23, 32, 40), and the same two-stage planetary architecture. The difference is in the motor input flange and the housing configuration: the L2A uses a lighter housing (85 kg) optimised for standard SAE motor flanges, while the L2B (95 kg) includes a heavier-duty housing with additional mounting provisions for specific motor adapter configurations and higher radial bearing capacity. If your application involves high side-loading on the wheel (large tyres, aggressive cornering, uneven terrain), the L2B may be the better choice. For standard applications, the L2A provides the same performance at lower weight and cost.

We evaluated the 603L2A ratio 23 against two European competitors for our 7-tonne telehandler platform. The Ever-Power unit matched the performance envelope at a price point that allowed us to hit our target production cost. We have 28 machines in the field now across UK rental fleets. The feedback from operators is that roading speed feels responsive and the machine handles 20% ramp grades with a loaded pallet without any hesitation from the hydrostatic circuit.

Self-propelled sprayer, ratio 40. The machine needs to crawl at 6-8 km/h through standing crops with precise speed control. Previously used chain drives that stretched every season and threw lubrication into the crop canopy. The sealed wheel drive eliminated both problems. After three spray seasons the seals are holding up well against the herbicide and fertiliser exposure. We ordered the same units for a second sprayer build.

Backhoe loader fleet, ratio 19 for road-heavy utility work. The drives perform fine and the roading speed is good for moving between job sites. The 4-star rating is a practical gripe: the oil drain plug on the 603L2A is positioned so that on our particular backhoe chassis, you have to jack the machine to get a drain pan underneath. An extended drain fitting or a relocated drain port would save 30 minutes per oil change across a fleet. Product quality and reliability are solid though.