601L1A Planetary Wheel Drive Gearbox — Single-Stage

601L1A
The Lightest Wheel Drive in the Catalogue

Most planetary wheel drive gearboxes pack two or three planetary stages into the housing. The 601L1A uses one. That single stage at 5.77:1 ratio is all that separates the hydraulic motor shaft from the wheel — and with fewer gears meshing, less energy is wasted as heat, fewer parts can wear, and the unit weighs barely more than a car tyre. For compact machines that do not need high reduction but absolutely need reliability and maximum efficiency per kilogram, this is the wheel drive to specify.

Every other wheel drive planetary gearbox in the Korea Ever-Power catalogue uses two or three planetary stages. The 601L1A uses one. That sounds like a limitation, but for machines that operate at moderate ground speeds (under 15 km/h) and draw torque from low-speed, high-displacement hydraulic motors, the single stage is the mechanically optimal solution.

Fewer gears meshing means 96% efficiency instead of the 93-95% typical of multi-stage planetary wheel drives. It means one fewer set of planet gears to inspect, one fewer sun gear that can wear, and roughly 40% less weight than a two-stage drive of equivalent torque class. On battery-electric or hybrid-electric compact vehicles, that efficiency gain extends range in a way that is difficult to achieve through any other single drivetrain change.

Find the required tractive force

F = GVW x (rolling resistance + gradient). For a 3,000 kg compact loader on firm soil (rolling resistance 0.04) climbing a 15% grade: F = 3,000 x 9.81 x (0.04 + 0.15) = 5,592 N. With two wheel drives sharing the load equally, each drive must produce 2,796 N at the tyre contact patch.

Convert to torque at the wheel

T = F x tyre radius. For a 400 mm rolling radius tyre: T = 2,796 x 0.40 = 1,118 Nm per wheel. The 601L1A delivers 1,750 Nm, providing a safety factor of 1.57 — well above the minimum 1.3 recommended for off-road applications with variable terrain.

Verify maximum speed

V = (motor rpm / ratio) x tyre circumference x 60 / 1,000,000. At 800 rpm motor input with 5.77 ratio and 0.4 m radius: V = (800 / 5.77) x (2 x 3.14 x 0.4) x 60 / 1,000,000 = 20.9 km/h. If your required top speed exceeds the calculated value, increase the hydraulic motor displacement or pump flow — not the gear ratio.

When a hydraulic system fails in the field — a burst hose, a dead pump, an electrical fault — the machine is stranded. Without a declutch, towing it back to the workshop means dragging the wheels against the locked gearbox and pressurised hydraulic motor. The result is usually a destroyed motor, blown seals, and an overheated gearbox that needs a full rebuild on top of the original repair.

The 601L1A solves this with a manual declutch lever accessible from outside the housing. One pull disconnects the planet carrier from the wheel hub, allowing the wheel to spin freely. The machine can then be towed at low speed (under 10 km/h) back to the workshop without any damage to the hydraulic circuit or the gearbox internals. Re-engaging the clutch takes seconds once the hydraulic system is repaired.

What is a planetary wheel drive gearbox and how does it differ from an axle-mounted reducer?

A planetary wheel drive gearbox is a compact speed reducer that mounts directly inside or onto the wheel hub, placing the reduction gears, parking brake, and output flange in a single sealed housing at the point of traction. Unlike axle-mounted reducers that transmit torque through a driveshaft, half-shaft, or chain to the wheel, the planetary wheel drive eliminates all intermediate transmission components. This reduces weight, removes chain or belt maintenance, and places the full torque path inside a sealed, oil-bath-lubricated housing that is protected from external contamination.

The 601L1A has a single ratio of 5.77. How do I get enough wheel torque for hill climbing?

The trick is on the motor side, not the gearbox side. A high-displacement, low-speed hydraulic motor (say, 400-630 cc/rev at 150-200 bar) produces high shaft torque, which the 5.77 ratio reduces to an appropriate wheel speed. The torque at the wheel (1,750 Nm max through the gearbox) is limited by the gearbox capacity, not the motor output. If the motor produces more than 1,750 / 5.77 = 303 Nm at the input shaft, the gearbox is at its rated limit. Size the motor to stay within this input torque envelope.

Can a hydraulic wheel drive planetary gearbox be paired with an electric motor?

Yes. The input shaft of the 601L1A accepts any motor that fits the spline interface specification — hydraulic or electric. Electric hub motor applications are increasingly common on battery-powered utility vehicles, autonomous guided vehicles, and airport ground support equipment. The key constraint is the 1,000 rpm maximum input speed — verify that the electric motor controller limits the shaft speed to this value at all times, including during regenerative braking transients where motor speed can momentarily overshoot.

What oil does a wheel drive planetary gearbox need, and how often should it be changed?

API GL-5 extreme pressure gear oil, SAE 80W-90 for most climates. For sustained operation below -15 deg C, use SAE 75W-90 synthetic. First oil change at 250 operating hours (running-in period). Subsequent changes every 2,000 hours or annually, whichever comes first. The oil volume in the 601L1A is small (approximately 0.8-1.2 litres depending on mounting angle), so each change is quick and inexpensive — there is no operational or economic reason to extend the interval.

How does the spring-applied parking brake hold the machine on a slope?

The brake is spring-applied and hydraulically released — it engages automatically whenever hydraulic pressure is removed (engine off, pump failure, hose burst). The 450-600 Nm static holding torque at the gearbox output translates to a holding force at the tyre contact patch that depends on the tyre radius. For a 400 mm radius tyre, the holding force per wheel is approximately 1,125-1,500 N. On a 3,000 kg machine, two wheel drive gearboxes together hold the vehicle on a gradient of approximately 8-10%. For steeper grades, add counterbalance valves in the hydraulic circuit as a secondary holding mechanism.

How do I choose between a wheel drive planetary gearbox and a worm gear wheel motor?

Planetary wheel drives offer 93-96% mechanical efficiency versus 40-70% for worm-gear wheel motors. This makes the planetary type the clear choice for any application where energy efficiency, battery range, or hydraulic heat management matters. Worm-gear wheel motors retain an advantage in one area: inherent self-locking at ratios above 30:1, which eliminates the need for a separate parking brake on slopes. If your application requires only low-speed, low-duty-cycle wheel rotation and self-locking is critical, a worm solution may be simpler. For everything else — particularly continuous-duty, high-efficiency, and high-reliability applications — the planetary wheel drive is the engineering standard.

Running these on four compact loaders at a nursery operation. Lots of mud, lots of tight turns on soft ground, lots of loading pallets of plants onto trucks. After two seasons the drives are solid — no leaks, no noise changes, no issues. The declutch saved us once when a hose blew on machine 3 and we were able to tow it back to the shed instead of calling a flatbed. That alone paid for itself.

We integrated the 601L1A into a battery-electric utility platform for airport ground support. The 96% efficiency is real — we measured 95.7% on our dyno across the operating range, which was the deciding factor over a two-stage competitor at 93.1%. The 4-star rating is because the input spline profile needed a custom coupling to mate with our BLDC motor shaft, and that coupling was not available from Ever-Power. We machined our own, but an adapter kit for common EV motor shafts would make this product much more accessible to the electric vehicle market.

Turf sprayer application. Replaced a chain drive that was throwing grease onto the fairways every time the wind changed direction. The sealed housing eliminated that problem completely. The lighter weight also noticeably reduced the rut depth on wet greens compared to the old setup. Simple unit, does what it needs to do.