Overview
The ZF 4651.003.004 3 WG 100(500) Powershift Transmission Assembly represents a complete, drop-in replacement unit engineered for heavy-duty off-highway applications. This fully assembled gearbox integrates the clutch pack, hydraulic valve body, and planetary gear sets into a single, pre-tested module. As the core power transfer component within the WG 100 Series, it converts engine torque into controlled, multi-speed output for wheel loaders, forklifts, and industrial tractors. The SKU 4651.003.004 designates a specific production revision optimized for 500 Nm input torque capacity, ensuring precise shift modulation under extreme loads. This assembly eliminates the need for piecemeal repairs, providing a direct exchange solution that restores original ZF performance specifications.
Symptoms of Failure
When the ZF 4651.003.004 assembly begins to degrade, operators will notice distinct operational deficits. Recognizing these early warning signs prevents catastrophic driveline damage and reduces costly downtime.
- Delayed or harsh directional shifts: A worn clutch pack or hydraulic seal within the assembly causes a noticeable lag when shifting from forward to reverse, often accompanied by a jarring engagement. This symptom typically worsens as transmission oil temperature rises.
- Internal oil leakage and pressure loss: Degraded O-rings or cracked housing bores allow transmission fluid to bypass the valve body. You may observe puddles under the bell housing or a persistent low-pressure warning on the dash, even after topping off the fluid.
- Gear slipping under load: When the machine is under heavy load—such as climbing a grade with a full bucket—the transmission may momentarily lose drive power, causing the engine to rev without corresponding wheel movement. This indicates worn friction discs or a failing torque converter lock-up.
- Unusual whining or grinding noises: Metallic sounds emanating from the transmission case, particularly in neutral or during deceleration, suggest bearing fatigue or planetary gear scoring. This often precedes complete mechanical seizure.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number / SKU | 4651.003.004 |
| Assembly Type | Complete Powershift Unit (3 WG 100(500)) |
| Input Torque Capacity | 500 Nm (369 lb-ft) |
| Dry Weight (approx.) | 185 kg (408 lbs) |
| Housing Material | High-strength cast iron (EN-GJS-500-7) |
| Overall Length (flange to flange) | 620 mm (24.4 in) |
| Mounting Pattern | SAE 3 with 10-bolt flange |
| OEM Reference | ZF 1320 301 001 (superseded) |
| Fluid Capacity (assembly only) | 8.5 liters (2.25 gallons) |
Compatibility
This complete unit is purpose-built for the ZF WG 100 Series transmission family, specifically the 3 WG 100(500) variant. It is directly compatible with the following ZF transmission models and their respective OEM equipment applications:
- ZF WG 100 (3-speed): Found in compact wheel loaders (e.g., Liebherr L506, JCB 407) and telescopic handlers.
- ZF WG 120 (3-speed): Used in mid-range forklifts (capacity 4-6 tons) and industrial sweepers.
- ZF WG 150 (3-speed): Common in agricultural tractors (e.g., Fendt 300 series) and rough-terrain cranes.
- ZF WG 180 (3-speed): Applied in larger wheel loaders (e.g., Volvo L60) and mining shuttle cars.
- ZF WG 200 (3-speed): Utilized in heavy-duty forklifts (8-10 ton capacity) and port equipment.
Note: While the 4651.003.004 is dimensionally identical to the WG 100 housing, verification of the bell housing bolt pattern and output yoke spline count is recommended for models outside the WG 100 series.
