Overview
The ZF 4644.120.475 PRESSURE REGULATOR is a precision-engineered hydraulic control component designed specifically for the WG 200 Series transmission family. This OEM genuine part modulates hydraulic pressure within the valve body assembly to ensure consistent clutch pack engagement and smooth gear shifts. The SKU 4644.120.475 sits directly within the main control bore of the transmission, acting as a critical interface between the pump output and the shift valves. When this regulator wears, the entire hydraulic balance of the transmission is compromised, leading to erratic performance. For full assembly integrity, this regulator works in concert with the 4644101176 TRANSMISSION HOUSING and the 4644301371 TRANSMISSION HOUSING, which provide the structural mounting and fluid routing channels.
Symptoms of Failure
- Delayed or harsh gear engagement: When the 4644.120.475 pressure regulator sticks or leaks internally, you will notice a pronounced lag when shifting from Neutral to Drive or Reverse, followed by a jarring engagement.
- Erratic shift timing under load: A worn regulator causes inconsistent line pressure, resulting in shifts that occur too early or too late, particularly when towing or climbing grades.
- Transmission overheating and fluid aeration: A failing pressure regulator allows excessive oil bypass, generating heat and aerating the fluid, which leads to foaming and reduced lubrication.
- Intermittent gear slipping: As the regulator loses its ability to maintain steady pressure, you may experience random slipping in higher gears, especially during steady-state cruising.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4644.120.475 |
| OEM Reference | ZF 4644.120.475 |
| Material | Hardened steel with nitrile sealing elements |
| Weight | 0.28 kg (0.62 lbs) |
| Overall Length | 82.5 mm |
| Outer Diameter | 28.0 mm |
| Operating Pressure Range | 8–22 bar (116–319 psi) |
| Seal Type | Integrated O-ring groove |
Compatibility
This pressure regulator is engineered for the ZF WG 200 Series, including the WG180, WG200, and WG210 models. It is a direct replacement for transmissions used in off-highway trucks, wheel loaders, and heavy-duty material handlers. The 4644.120.475 is also compatible with certain WG 150 variants that share the same valve body architecture. Always verify the 0730365067 TYPE PLATE on your transmission to confirm the exact series designation before ordering. Additionally, the 0631311009 GROOVED STUD is often replaced simultaneously to ensure proper alignment of the valve body cover.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101176 | TRANSMISSION HOUSING | Main structural casing for gear and valve assembly |
| 4644301371 | TRANSMISSION HOUSING | Secondary housing section for clutch packs |
| 0730365067 | TYPE PLATE | Identification plate with model and serial number |
| 0631311009 | GROOVED STUD | Alignment stud for valve body cover installation |
| 4644303060 | COVER PLATE | Seals the valve body cavity |
| 4644201011 | COVER PLATE | Alternate cover for different valve body configurations |
| 4644201010 | COVER PLATE | Lower profile cover plate variant |
| 4644301372 | COVER PLATE | Reinforced cover for high-pressure applications |
| 0636610028 | STUD | Threaded fastener for housing attachment |
| 0634306525 | O-RING | Hydraulic seal for pressure regulator bore |
