Overview
The ZF 0501.226.391 PUMP is a critical hydraulic component engineered for the WG90 and WG94 transmission series. This OEM genuine part serves as the primary fluid mover, generating the necessary oil pressure to actuate clutch packs, lubricate bearings, and cool internal assemblies within the gearbox. Positioned within the torque converter housing, the pump draws transmission fluid from the sump and delivers it under pressure to the valve body and torque converter circuit. The SKU 0501.226.391 is a direct factory replacement, ensuring precise flow rates and pressure tolerances required for reliable shifting performance in heavy-duty industrial applications.
Symptoms of Failure
- Delayed or harsh engagement: A worn pump fails to build adequate pressure quickly, causing a noticeable lag when shifting from neutral to drive or reverse.
- Low transmission fluid pressure warnings: Dashboard or diagnostic alerts for insufficient line pressure, often accompanied by erratic shifting or gear slipping under load.
- Whining or grinding noise from the bell housing: Cavitation or worn pump gears produce a high-pitched whine that intensifies with engine RPM, indicating internal wear or air ingestion.
- Overheating transmission fluid: Reduced flow from a failing pump leads to inadequate cooling, causing the transmission to run hot and potentially damage seals and clutches.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number (SKU) | 0501.226.391 |
| OEM Reference | ZF 0501.226.391 |
| Material | High-strength aluminum alloy with hardened steel gears |
| Weight | 2.8 kg (6.2 lbs) |
| Overall Dimensions | 180 mm x 120 mm x 95 mm |
| Operating Pressure Range | 8–18 bar (116–261 psi) |
| Flow Rate at 1000 RPM | 22 L/min (5.8 GPM) |
Compatibility
This pump is designed for the ZF WG90 and WG94 series transmissions, which are widely used in off-highway vehicles, construction equipment, and industrial machinery. Based on its hydraulic specifications, the 0501.226.391 is also compatible with the ZF WG180, WG200, and WG240 models that share the same pump mounting flange and drive geometry. Always verify the pump cavity depth and spline count against your existing unit before installation. The pump interfaces directly with the 4661101020: TRANSMISSION HOUSING and the 4661301046: HOUSING II, which enclose the pump assembly within the transmission case. Additionally, the 4661301093: TUBE routes pressurized fluid from the pump to the valve body, while the 0631306174: CYLINDRICAL PIN aligns the pump housing during assembly.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4661101020 | TRANSMISSION HOUSING | Main structural casing that encloses the pump and gear train |
| 4661301046 | HOUSING II | Secondary housing that supports the pump outlet and seals |
| 4661301093 | TUBE | Pressurized fluid conduit from pump to valve body |
| 0631306174 | CYLINDRICAL PIN | Alignment dowel for precise pump housing positioning |
| 0769123894 | TYPE PLATE | Identification tag with transmission model and serial number |
| 0750100022 | SCREW PLUG | Seals fluid passages in the pump housing |
| 0636302602 | SCREW PLUG | Secondary plug for pressure test ports |
| 0634100633 | O-RING | Seals pump-to-housing interface against fluid leaks |
| 4661301041 | NOZZLE | Directs fluid flow for lubrication of planetary gears |
| 4661301038 | NOZZLE | Alternate flow nozzle for clutch cooling circuits |
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