Overview
The ZF 4644.120.407 PRESSURE REGULATOR is a critical hydraulic control component engineered specifically for the WG200 series transmission. This OEM genuine part precisely modulates oil pressure within the valve body assembly, ensuring consistent clutch engagement and smooth gear shifts. The SKU 4644.120.407 directly governs the main circuit pressure, acting as the primary interface between the transmission’s hydraulic pump and the shift solenoids. Without this regulator, the entire WG200 system cannot maintain the calibrated pressure needed for torque converter lockup or planetary gearset operation. It is typically mounted inside the main control unit, adjacent to the TRANSMISSION HOUSING (4644101216) and the TRANSMISSION HOUSING (4644301223), which together form the sealed hydraulic circuit.
Symptoms of Failure
- Erratic shift timing and gear slipping: A worn 4644.120.407 pressure regulator causes inconsistent hydraulic pressure, leading to delayed upshifts or sudden downshifts under load. Operators often report “WG200 transmission slipping in 3rd gear” as a common search query.
- Oil leaks around the valve body: When the regulator’s internal seals degrade, transmission fluid seeps past the bore, resulting in visible drips near the TYPE PLATE (0730365067) area. This is frequently searched as “ZF WG200 pressure regulator oil leak.”
- Torque converter shudder or overheating: A failing regulator cannot maintain lockup pressure, causing the converter to slip and generate excessive heat. Technicians often diagnose this as “WG200 transmission overheating pressure regulator.”
- Harsh engagement from Neutral to Drive: Sudden pressure spikes from a stuck regulator spool produce jarring engagement, often described as “ZF transmission hard shift from N to D.”
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4644.120.407 |
| OEM Reference | ZF 4644.120.407 |
| Material | Hardened steel spool with anodized aluminum body |
| Weight | 0.32 kg (0.71 lbs) |
| Overall Length | 85 mm |
| Outer Diameter | 28 mm |
| Operating Pressure Range | 8–22 bar (116–319 psi) |
| Seal Type | PTFE backup ring with NBR O-ring |
Compatibility
This pressure regulator is engineered for the ZF WG200 series transmissions, including the WG180, WG200, and WG210 variants. It is also compatible with select off-highway and industrial drivelines that utilize the WG200 valve body architecture. The part directly interfaces with the GROOVED STUD (0631311009) for secure mounting. Always verify your transmission’s serial number against the OEM parts catalog before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101216 | TRANSMISSION HOUSING | Encloses the valve body and gear train |
| 4644301223 | TRANSMISSION HOUSING | Secondary housing for hydraulic circuit |
| 0730365067 | TYPE PLATE | Identification plate for transmission model |
| 0631311009 | GROOVED STUD | Mounting fastener for pressure regulator |
| 4644303060 | COVER PLATE | Seals the valve body access port |
| 4644303061 | COVER PLATE | Alternate cover plate for different bore sizes |
| 0634306525 | O-RING | Seals regulator bore against fluid bypass |
| 0636305026 | SCREW PLUG | Closes test ports in the valve body |
| 4644301279 | SCREEN SHEET | Filters debris entering the regulator |
| 4644301088 | SEALING CAP | Protects unused hydraulic passages |
