Overview
The ZF 4644.004.231 4 WG 180(555) Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway applications. This assembly integrates the torque converter, planetary gear sets, and clutch packs into a single, pre-assembled module, serving as the core power transfer component in the WG 180 series. The SKU 4644.004.231 is a direct replacement for the original 4 WG 180(555) configuration, ensuring seamless installation when paired with a compatible TRANSMISSION HOUSING or TRANSMISSION HOUSING variant. This assembly eliminates the need for piecemeal rebuilding, reducing downtime in wheel loaders, graders, and industrial tractors.
Symptoms of Failure
- Erratic gear engagement or slipping under load: When the internal clutch packs or sprag clutches wear, the transmission may hesitate or fail to hold gear during high-torque operations, such as pushing or digging.
- Torque converter shudder or overheating: A failing assembly often produces vibration at low speeds, accompanied by rising transmission fluid temperatures due to internal leakage across worn seals.
- Delayed forward/reverse shifting: Worn valve body components or degraded O-rings cause a noticeable lag when switching direction, often accompanied by a hard “clunk” as pressure builds.
- External oil leaks near the bell housing: Cracks in the COVER PLATE or a degraded O-RING can allow ATF to weep, leading to low fluid levels and eventual gear starvation.
Technical Specifications
| Parameter | Value |
|---|---|
| Overall Length | 685 mm (27.0 in) |
| Dry Weight | 195 kg (430 lbs) |
| Housing Material | High-strength cast iron (GGG-40) |
| Max Input Torque | 1,800 Nm (1,328 lb-ft) |
| OEM Reference | ZF 4 WG 180(555) |
| Fluid Capacity | 12.5 liters (3.3 gal) |
Compatibility
This complete unit is engineered for the ZF WG 180 series, specifically the 4-speed powershift variant with a 555 torque converter code. It is also mechanically compatible with the WG 200 series when using the appropriate GEAR SHIFT HOUSING adapter. The assembly fits ZF 4 WG-180, 4 WG-200, and 4 WG-210 models used in Volvo L70/L90 loaders, Case 821/921 graders, and Liebherr L524 telehandlers. Always verify bell housing bolt patterns before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101249 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301402 | TRANSMISSION HOUSING | Alternate housing for deep-sump applications |
| 4644301298 | COVER PLATE | Seals the valve body access port |
| 0634306323 | O-RING | Prevents fluid bypass at cover joints |
| 0636305026 | SCREW PLUG | Closes pressure test ports |
| 4644301279 | SCREEN SHEET | Filters debris from lube circuit |
| 4644301088 | SEALING CAP | Protects unused hydraulic ports |
| 4644159347 | SHIFT SYSTEM | Electro-hydraulic shift module |
| 4475280036 | SCREW-IN SLEEVE | Torque converter hub bearing retainer |
| 4644306511 | GEAR SHIFT HOUSING | Houses shift forks and detents |
