Overview
The ZF 4475.280.234 SCREW PLUG is a critical sealing component engineered for the WG100, WG130, and WG131 transmission series. This OEM genuine part functions as a positive closure for fluid passages within the transmission housing, preventing lubricant loss and maintaining hydraulic pressure essential for clutch and gear actuation. The SKU 4475.280.234 is specifically designed to withstand high thermal cycling and vibration loads found in heavy-duty industrial drivetrains. When installed correctly, this screw plug ensures the differential assembly remains properly lubricated, working in concert with components like the 2099109038 DIFFERENTIAL to maintain system integrity.
Symptoms of Failure
- Transmission fluid seepage at housing joints: A worn or cross-threaded 4475.280.234 screw plug allows oil to weep past the sealing face, often visible as dark residue on the transmission casing.
- Intermittent gear engagement hesitation: When this plug fails to seal, hydraulic pressure drops can cause delayed shifts, particularly under load in WG130 models.
- Contaminated lubricant from external debris ingress: A compromised plug permits dirt and moisture entry, leading to accelerated wear on the 2098309008 CROWN WHEEL and other precision gears.
- Audible whining from differential area: Loss of oil volume due to plug failure creates insufficient lubrication for the 2098209016 DIFFERENTIAL, producing metallic noise during operation.
Technical Specifications
| Parameter | Value |
|---|---|
| OEM Part Number | 4475.280.234 |
| Thread Size | M18 x 1.5 (estimated) |
| Overall Length | 22 mm |
| Head Diameter | 24 mm hex |
| Material | Case-hardened steel, zinc-plated |
| Sealing Type | Integrated copper washer |
| Weight | 0.035 kg |
| Torque Specification | 45 Nm (dry thread) |
| Operating Temperature Range | -40°C to +150°C |
Compatibility
This screw plug is directly compatible with ZF WG100, WG130, and WG131 transmissions used in agricultural tractors, construction loaders, and industrial material handlers. It also fits select WG180 and WG200 variants where the differential housing uses identical thread patterns. The 4475.280.234 replaces the 0631329086 SPRING PIN in later production runs and should be paired with a new 0730300820 THRUST WASHER during installation. For complete differential rebuilds, verify fitment with the 2095309059 DIFF.HOUSING to ensure proper clearance.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 2099109038 | DIFFERENTIAL | Distributes torque between drive wheels |
| 2098309008 | CROWN WHEEL | Transfers power from pinion to differential |
| 2098209016 | DIFFERENTIAL | Compact unit for WG130 series |
| 2095309059 | DIFF.HOUSING | Encloses differential gear set |
| 0631329086 | SPRING PIN | Retains shift fork position |
| 0730300820 | THRUST WASHER | Reduces axial play in gear stacks |
| 4482360002 | AXLE BEVEL GEAR | Transmits rotation to wheel axles |
| 2095309081 | DIFFERENTIAL AXLE | Connects differential to final drive |
| 5838300811 | THRUST WASHER | Heavy-duty axial load bearing |
| 4482360001 | DIFFERENTIAL BEVEL GEAR | Primary gear in differential assembly |
