Overview
The ZF 4642.306.006 PISTON for WG 150 is a critical hydraulic actuation component engineered for precise clutch and brake application within ZF’s WG series powershift transmissions. This OEM genuine part, identified by SKU 4642.306.006, converts hydraulic pressure into linear mechanical force, directly engaging the clutch packs that govern gear selection and torque flow. Located within the valve body and clutch housing assembly, this piston ensures smooth, positive shifts under heavy load conditions. When paired with a robust TRANSMISSION HOUSING, it maintains the necessary sealing and alignment for consistent hydraulic circuit performance.
Symptoms of Failure
- Delayed or harsh gear engagement: A worn or scored piston surface causes internal hydraulic leakage, leading to sluggish clutch application or abrupt, jarring shifts during acceleration.
- Intermittent transmission slipping under load: As the piston loses its sealing integrity, the transmission may momentarily lose drive power, especially when climbing grades or carrying heavy payloads.
- Contaminated transmission fluid with metallic debris: Degradation of the piston’s anodized coating or aluminum body sheds fine particles into the oil, often visible during routine fluid changes.
- Low hydraulic pressure warnings or erratic operation: Internal bypassing past the piston reduces system pressure, triggering diagnostic trouble codes or causing the transmission to default to a limp-home mode.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number / SKU | 4642.306.006 |
| OEM Reference | ZF 4642.306.006 (Genuine) |
| Material | High-strength aluminum alloy with hard anodized coating |
| Outer Diameter | Approx. 85 mm |
| Overall Height | Approx. 38 mm |
| Weight | 0.24 kg (0.53 lbs) |
| Seal Grooves | 2 (for O-rings, not included) |
| Surface Finish | Ra 0.4 µm (polished) |
Compatibility
This piston is specifically designed for the ZF WG 150 series transmission, but its hydraulic profile also suits several related models in the WG family. Verified compatibility includes the WG 150, WG 151, and WG 152 variants. It may also be retrofitted into earlier WG 180 and WG 200 series units when used with the correct HOUSING and THREADED BUSH to accommodate slight dimensional differences. Always confirm the piston stroke and bore diameter against your transmission’s service manual. For identification purposes, the TYPE PLATE on your transmission housing provides the exact model code.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101047 | TRANSMISSION HOUSING | Encloses and supports the piston and clutch assembly |
| 4644301380 | HOUSING | Secondary housing for valve body and piston alignment |
| 4644301189 | THREADED BUSH | Provides threaded anchor point for piston return spring |
| 0730365067 | TYPE PLATE | Identification plate with transmission model and serial number |
| 0631311009 | GROOVED STUD | Secures housing components with positive locking |
| 4644301161 | COVER PLATE | Seals the piston bore and retains hydraulic pressure |
| 0636100621 | HEXAGON SCREW | Fastens cover plate and housing sections |
| 0631610020 | SET SCREW | Adjusts and locks threaded bush position |
| 0634801098 | SEALING RING | Prevents fluid bypass at housing joints |
| 4644301117 | FIXING PLATE | Retains piston and spring assembly during operation |
