Overview
The ZF 0091.312.023 CYLINDER is a precision-machined hydraulic actuation component designed for the WG250, WG260, and WG310 series transmissions. This OEM genuine part serves as the primary piston housing within the clutch pack assembly, converting hydraulic pressure into linear mechanical force to engage or disengage gear sets. The SKU 0091.312.023 is manufactured to ZF’s original tolerances, ensuring a seamless seal within the TRANSMISSION HOUSING and preventing cross-contamination between oil circuits. Without this cylinder, the transmission cannot modulate clutch pressure, leading to immediate drivability loss in heavy-duty applications.
Symptoms of Failure
- Delayed or harsh gear engagement: When the cylinder bore wears, hydraulic pressure bleeds past the piston seals, causing a noticeable lag when shifting from neutral to drive or reverse.
- Intermittent oil leaks near the clutch housing: Cracks or scoring on the cylinder wall allow ATF to escape, often pooling around the HOUSING interface.
- Slipping under load: A worn cylinder cannot maintain clamping force on the clutch discs, resulting in RPM flare during acceleration or hill climbs.
- Erratic shift patterns: Internal scoring causes inconsistent piston travel, leading to random upshifts or downshifts without driver input.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 0091.312.023 |
| Material | High-strength aluminum alloy with hard-anodized bore |
| Bore Diameter | 85.0 mm (nominal) |
| Overall Length | 142.5 mm |
| Weight | 0.87 kg (1.92 lbs) |
| OEM Reference | ZF 0091.312.023 (genuine) |
| Seal Type | PTFE lip seal (integrated) |
Compatibility
This cylinder is engineered for the ZF WG series powershift transmissions. It is a direct fit for the WG250, WG260, and WG310 models commonly used in construction and agricultural machinery. While the part is not shared with the WG180 or WG200 series due to different bore diameters, it is compatible with all sub-variants of the WG250/260/310 families, including those with integrated COVER assemblies. Always verify the serial number against the CONNECTING PART to confirm fitment.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4646101062 | TRANSMISSION HOUSING | Encloses the gear train and cylinder assembly |
| 4646301104 | HOUSING | Supports the clutch pack and valve body |
| 4646301300 | COVER | Seals the cylinder bore and retains pressure |
| 4646323018 | CONNECTING PART | Links the cylinder to the shift fork mechanism |
| 0636015304 | HEXAGON SCREW | Fastens the cylinder to the housing |
| 0636101828 | CAP SCREW | Secures the cover plate over the cylinder |
| 4646301100 | COVER SHEET | Thin gasket between housing and cover |
| 4646301112 | COVER SHEET | Alternate thickness gasket for tolerance adjustment |
| 0730365067 | TYPE PLATE | Identification tag for transmission model |
| 0631311009 | GROOVED STUD | Alignment dowel for cylinder positioning |
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