602L2 Planetary Wheel Drive Gearbox Reducer

① Hydrostatic Dynamic Braking

In a closed-loop hydrostatic transmission, reducing the pump displacement to zero while the vehicle is moving forces the motor to act as a pump against the system pressure. This creates a controlled deceleration torque at the wheel without any mechanical brake engagement. The 602L2 transmits this braking torque through the same gear mesh that handles propulsion — the gears do not distinguish between driving and braking loads.

② Counterbalance Valves

Counterbalance valves installed in the motor circuit lines prevent the wheel from overrunning the motor on downhill grades. They create a controlled back-pressure that limits the maximum wheel speed regardless of gradient. On the 602L2, counterbalance valves are essential for any machine that operates on slopes — without them, a loaded vehicle descending a grade will accelerate uncontrollably until something fails.

③ Motor-Integrated Parking Brake

Many hydraulic motors (Rexroth A6VM, Eaton, Danfoss) offer an integrated spring-applied, hydraulic-release parking brake as a factory option. This brake acts on the motor shaft, which is multiplied through the 602L2 gear ratio to the wheel. A motor brake producing 30 Nm at ratio 20 delivers 600 Nm of holding torque at the wheel — more than adequate for flat-terrain parking. For slope holding, verify the multiplication is sufficient for your vehicle weight and gradient.

Most planetary wheel drive gearboxes offer a fixed list of discrete ratios — the 603L2A, for example, gives you four choices and you pick the closest one. The 602L2 works differently. The two planetary stages inside the 602L2 can be configured with different sun and ring gear combinations to produce any ratio between 12.4 and 25.8. You specify the exact ratio your hydraulic circuit requires, and the gears are manufactured to match.

This eliminates the motor-sizing compromise that engineers face with fixed-ratio gearboxes. Instead of choosing a motor displacement that is close to optimal for the nearest available ratio, you choose the ideal motor displacement first, calculate the exact ratio needed, and order the 602L2 with that ratio built in. The result is a drive system where the motor operates at its peak efficiency point rather than 5-15% away from it — a difference that compounds over thousands of operating hours into measurable fuel and hydraulic oil temperature savings.

Compact Wheel Loaders (6-10 Tonne)

Closed-loop hydrostatic wheel loaders with variable-displacement pump-motor circuits do not need a gearbox brake because the pump provides full dynamic braking by reducing displacement to zero. The 602L2 at a custom ratio matched to the specific motor displacement and tyre size delivers exactly the tractive effort and ground speed the machine was designed around — not the nearest available approximation. OEM engineers specify the motor first, then order the gearbox ratio to match.

Heavy-Duty AGVs and Automated Transport Vehicles

Automated guided vehicles in manufacturing plants, port container yards, and logistics centres operate on flat, smooth surfaces where slope-holding brakes are unnecessary. The braking function is handled entirely by the electric drive motor through regenerative braking controlled by the vehicle automation system. The 602L2 removes the dead weight and maintenance liability of an unused brake, and the custom ratio capability allows AGV designers to optimise the wheel drive for the exact speed and torque profile of their automated route without compromise.

Industrial Tow Tractors and Platform Carriers

Factory tow tractors, agricultural platform carriers, and heavy-load transport carts that operate exclusively on level surfaces and use motor-integrated parking brakes for stationary holding. The 602L2 paired with a Rexroth A6VM or Eaton motor with built-in brake provides a complete propulsion-and-parking solution at lower total weight and cost than a wheel drive with a separate internal brake that duplicates the motor brake function.

Is it legal to use a wheel drive without an integrated brake on public roads?

Regulations vary by jurisdiction. Most countries require a redundant braking system (service brake plus parking brake) for road-registered vehicles. The 602L2 can meet this requirement if the vehicle has: (1) a hydrostatic service brake (pump destroking) plus (2) a motor-integrated parking brake — neither of which is inside the wheel drive gearbox. However, some jurisdictions specifically require a mechanical brake at the wheel hub. Verify local vehicle regulations before specifying the 602L2 for any road-going application.

Can I order a 602L2 with a brake added later?

No. The 602L2 housing is not designed to accommodate a brake module — there is no cavity, no spline interface, and no hydraulic porting for a brake disc and piston. If you need the 5,000 Nm torque class with an integrated brake, the 605L2 (7,000 Nm, with 220-310 Nm brake) is the nearest model with built-in brake capability. Alternatively, pair the 602L2 with a hydraulic motor that has an integrated shaft brake.

How precisely can the custom ratio be manufactured?

Within the 12.4-25.8 range, the achievable ratios are constrained by the integer tooth count combinations of the sun, planet, and ring gears. This means the exact ratio you request will be matched to the nearest manufacturable value, which is typically within 0.5% of the target. For example, if you request 18.00, the delivered ratio might be 17.93 or 18.06 depending on the gear tooth count combination. The exact as-built ratio is confirmed during the quotation process and documented on the serial number certificate.

What counterbalance valve setting should be used with the 602L2 on a 10% grade?

The counterbalance valve pilot ratio and cracking pressure depend on the specific hydraulic motor displacement, the system operating pressure, and the vehicle loaded weight. As a starting point: calculate the gravitational force component on the 10% grade (GVW x 9.81 x 0.10), convert to torque at the motor shaft (divide by tyre radius, then by gear ratio), and set the counterbalance cracking pressure to produce this torque at the motor plus a 15-20% margin. Fine-tune on the machine by driving down the target grade loaded and adjusting until descent speed is controlled without surging.

How does removing the brake affect the wheel drive planetary gearbox reliability?

Positively. The spring-applied brake is a wear component — the friction disc degrades over time, the springs fatigue, and the hydraulic release piston seals can leak. By removing the brake entirely, the 602L2 eliminates a failure mode, a maintenance task (brake inspection and disc replacement), and a source of heat generation inside the housing. The remaining internal components (gears, bearings, seals) are identical to braked models and carry the same service life expectations.

Why not use a worm gear wheel drive that has inherent self-locking instead?

A worm gear wheel motor with self-locking at ratios above 30:1 does eliminate the need for a separate brake — but at 40-65% efficiency, it wastes 30-55% of the input energy as heat. On a 5,000 Nm application, that means 2,500-4,000 watts of continuous heat generation per wheel that must be dissipated by the housing. The 602L2 at 95% efficiency wastes only 250 watts at the same torque. For any application running more than a few hundred hours per year, the energy savings of the planetary design far outweigh the cost of providing external braking in the hydraulic circuit.

We specified the 602L2 at ratio 17.2 for a new 8-tonne wheel loader platform. The custom ratio eliminated a motor oversizing issue we had on the previous generation where the closest available fixed ratio forced us to use a 71 cc motor when the ideal displacement was 63 cc. Smaller motor means lower standby losses, which reduced average hydraulic oil temperature by 11 deg C across a full work cycle. The brake-free design was not a concern because our Rexroth A6VM motors have integrated parking brakes and the closed-loop circuit provides full dynamic braking.

Container yard AGV, 20-tonne payload capacity. The 602L2 at ratio 22.6 paired with BLDC hub motors. We evaluated three wheel drive suppliers and the 602L2 was the only one that offered a custom ratio within our required range — the others only had fixed ratios at 20 and 25, neither of which matched our motor controller efficiency map. The no-brake design was actually a requirement for us, not a compromise. Our AGV uses regenerative braking and the vehicle controller manages all deceleration electronically. A mechanical brake would have interfered with the regen control loop.

Used the 602L2 on a factory tow tractor project. Good product, works as specified. The custom ratio at 14.8 gave us the exact top speed our client needed. The reason for 4 stars is that the installation manual does not make it clear enough that external braking is mandatory — the safety warning is in the manual but not prominently displayed on the product label or the shipping crate. For a brake-free product, I would expect a large, obvious warning sticker on the housing itself that says "NO INTERNAL BRAKE — EXTERNAL BRAKING SYSTEM REQUIRED." This matters when the unit passes through hands of installers who may not read the manual cover to cover.