Overview
The ZF 0501.309.447 BLOW-OFF RING is a precision-engineered component designed to regulate internal pressure within ZF powershift transmissions. Located in the clutch pack or hydraulic control circuit, this ring ensures that excess oil pressure is safely vented during gear changes, preventing hydraulic lock and protecting seals. The SKU 0501.309.447 is an OEM genuine part, critical for maintaining consistent shift quality in heavy-duty construction machinery. When installed alongside the 4108101112: HOUSING and 4108201177: HOUSING, it forms a sealed pressure boundary that directly influences transmission longevity.
Symptoms of Failure
- Erratic or delayed gear engagement — A worn blow-off ring cannot maintain proper backpressure, causing sluggish shifts or sudden clutch grab.
- Transmission oil leaks near the clutch housing — Cracks or deformation in the ring allow pressurized fluid to bypass seals, leading to visible drips.
- Overheating transmission fluid — Failed pressure regulation forces the pump to work harder, raising operating temperatures and accelerating wear.
- Whining or chattering noise during shifts — Air entrainment from improper blow-off creates cavitation, audible as metallic sounds.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 0501.309.447 |
| Material | Nitrided steel (DIN 1.8519) |
| Outer Diameter | 142 mm |
| Inner Diameter | 118 mm |
| Thickness | 8.5 mm |
| Weight | 0.32 kg |
| OEM Reference | ZF 0501.309.447 |
| Surface Finish | Ground, Ra ≤ 0.8 µm |
Compatibility
This blow-off ring is primarily used in ZF WG180, WG200, and WG211 series powershift transmissions found in wheel loaders, dozers, and graders. It also fits select 4WG-200 and 6WG-200 variants. For proper installation, always pair with a new 0636302056: SCREW PLUG and inspect the 4108301304: BEARING COVER for scoring. Verify transmission model number before ordering.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4108101112 | HOUSING | Encloses clutch pack assembly |
| 4108201177 | HOUSING | Torque converter housing section |
| 0636302056 | SCREW PLUG | Seals hydraulic test ports |
| 4108301304 | BEARING COVER | Protects output shaft bearing |
| 4108306173 | GASKET | Prevents oil seepage at mating surfaces |
| 0750110040 | SHAFT SEAL | Dynamic seal for rotating shafts |
| 4108102042 | INPUT | Input shaft assembly |
| 4108302099 | PLANET CARRIER | Holds planetary gears |
| 4108302007 | BEARINGSHEET | Thrust washer for gear sets |
| 0635332196 | BALL BEARING | Supports rotating elements |
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