Overview
The ZF 4646.120.006 PRESSURE REGULATOR is a precision-engineered hydraulic control component specifically designed for the WG 250 series transmission. This OEM genuine part governs the modulation of hydraulic pressure within the valve body assembly, ensuring consistent clutch and brake application during gear shifts. The SKU 4646.120.006 directly interfaces with the main TRANSMISSION HOUSING to maintain optimal line pressure, preventing torque converter lockup fluctuations. As a critical flow-control device, it compensates for thermal expansion and viscosity changes in the transmission fluid, safeguarding the entire drivetrain from pressure spikes.
Symptoms of Failure
- Erratic shift timing and gear hunting: A worn 4646.120.006 regulator causes inconsistent hydraulic pressure, leading to delayed or harsh upshifts, particularly under load.
- Transmission fluid leakage near the valve body: Internal seal degradation on this pressure regulator results in external oil seepage around the HOUSING interface, often mistaken for pan gasket failure.
- Torque converter shudder at highway speeds: When the regulator fails to maintain steady lockup pressure, drivers experience a rhythmic vibration during cruise conditions.
- Low line pressure codes (P0740-P0745): Diagnostic scans frequently reveal pressure-related fault codes when this OEM part loses its ability to maintain hydraulic balance.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4646.120.006 |
| OEM Reference | ZF 4646.120.006 |
| Material | Hardened steel spool with aluminum alloy body |
| Weight | 0.34 kg (0.75 lbs) |
| Operating Pressure Range | 8-22 bar (116-319 psi) |
| Temperature Range | -40°C to +120°C |
| Thread Size | M12 x 1.5 |
| Seal Type | Nitrile rubber O-ring |
Compatibility
This pressure regulator is engineered for the ZF WG series powershift transmissions, specifically the WG250 model. It is also compatible with the WG180, WG200, and WG210 variants when used in conjunction with the correct COVER assembly. The part fits both early and late production runs of the WG250 series, provided the HEXAGON SCREW torque specifications are followed during installation. Always verify the valve body casting number before ordering, as some WG250 units with serial numbers above 850,000 may require a revised regulator.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4646101066 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4646301228 | HOUSING | Valve body enclosure |
| 4646301251 | COVER | Seals valve body cavity |
| 0636015304 | HEXAGON SCREW | Fastener for housing assembly |
| 0636101828 | CAP SCREW | Threaded fastener for cover |
| 4646301100 | COVER SHEET | Protective plate for valve body |
| 4646301217 | COVER SHEET | Secondary protective plate |
| 4646201007 | SCREEN SHEET | Filter mesh for hydraulic fluid |
| 0730365125 | TYPE PLATE | Identification label for transmission |
| 0631311009 | GROOVED STUD | Alignment pin for housing |
