Overview
The ZF 4699.803.042 GK20 is a precision-engineered OEM genuine part designed for the hydraulic control system within heavy-duty construction machinery transmissions. This component functions as a critical valve or actuator element, regulating oil flow and pressure to ensure smooth gear engagement and torque converter lock-up. Positioned within the valve body assembly, the SKU 4699.803.042 directly influences shift quality and overall drivetrain reliability. When paired with the 4699101045 HOUSING and the 4699301108 HOUSING, it forms a sealed hydraulic circuit that withstands extreme pressures and thermal cycling common in off-road applications.
Symptoms of Failure
- Erratic or delayed gear engagement: Worn internal seals or spools in the 4699.803.042 cause inconsistent hydraulic pressure, leading to hesitation when shifting from neutral to drive or reverse.
- Transmission overheating under load: A failing GK20 can restrict oil flow, increasing friction and heat generation, particularly during heavy digging or grading operations.
- Oil contamination or metallic debris in the pan: Degradation of the part’s internal surfaces sheds fine metal particles, which accelerate wear on the 4699301085 COVER and adjacent components.
- Intermittent loss of forward or reverse: Partial blockage within the valve body due to a worn 4699.803.042 results in unpredictable clutch pack application, often misdiagnosed as a solenoid failure.
Technical Specifications
| Parameter | Value |
|---|---|
| OEM Part Number | 4699.803.042 |
| Designation | GK20 (Valve/Actuator) |
| Material | Hardened steel with zinc-nickel plating |
| Weight | 0.85 kg (1.87 lbs) |
| Operating Pressure | 18-25 bar (261-363 psi) |
| Seal Type | PTFE energized lip seal |
| Temperature Range | -40°C to +120°C (-40°F to +248°F) |
Compatibility
This OEM genuine part is engineered for ZF’s powershift transmission series commonly deployed in construction machinery, including wheel loaders, dozers, and excavators. It is a direct fit for the WG180, WG200, and WG210 models, as well as the 4WG-200 and 6WG-200 variants. The 4699.803.042 also integrates with the 4699301014 THREAD PROTECTIVE SHIELD to prevent thread damage during installation. For optimal sealing integrity, always replace the 0634303141 O-RING and 0734307407 PROTECTION CAP concurrently.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4699101045 | HOUSING | Encloses the valve body assembly |
| 4699301108 | HOUSING | Secondary housing for hydraulic passages |
| 4699301085 | COVER | Seals the valve chamber |
| 4699301014 | THREAD PROTECTIVE SHIELD | Prevents thread galling during assembly |
| 0634303141 | O-RING | Static seal for fluid retention |
| 0734307407 | PROTECTION CAP | Shields ports from debris |
| 0634301843 | SHAFT SEAL | Dynamic seal for rotating shafts |
| 0630502034 | RETAINING RING | Secures internal components axially |
| 0637885612 | BREATHER | Equalizes internal pressure |
| 0636102023 | CAP SCREW | Fastens housing sections |
