Overview
The ZF 4646.122.012 PRESSURE OIL PUMP is a critical hydraulic component engineered for the WG310 transmission series and select WG 258, WG 260, WG 261, WG 308, and WG 311 models. This OEM genuine part is responsible for generating and maintaining the precise oil pressure required to actuate clutch packs, lubricate bearings, and cool internal assemblies. Positioned within the transmission’s valve body circuit, the pump draws fluid from the sump and delivers it under pressure to the torque converter and shift elements. The SKU 4646.122.012 is a direct replacement that ensures consistent flow rates and pressure stability, preventing erratic shifting and thermal damage in heavy-duty industrial applications.
Symptoms of Failure
- Low or erratic hydraulic pressure – When the pump wears, you may notice delayed engagement or a soft shift feel, especially under load. This is a common long-tail search query for “ZF transmission pressure loss.”
- Audible whining or groaning from the transmission – Cavitation or worn gears inside the pump produce a distinct noise that intensifies with RPM, often searched as “ZF oil pump whine noise.”
- Oil leaks around the pump housing or cooler lines – Seal degradation or housing cracks cause fluid to escape, leading to low oil levels and overheating. This symptom is frequently queried as “ZF transmission oil leak pump area.”
- Intermittent gear slipping or harsh shifting – Insufficient pressure from a failing pump results in clutch pack slippage, which can escalate to complete transmission failure if ignored.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number | 4646.122.012 |
| OEM Reference | ZF 4646.122.012 |
| Material | High-strength cast iron with hardened steel gears |
| Weight | Approx. 2.8 kg (6.2 lbs) |
| Dimensions (L x W x H) | 180 mm x 120 mm x 95 mm |
| Operating Pressure | 10–18 bar (145–261 psi) |
| Flow Rate | 18–22 L/min at 1500 RPM |
Compatibility
This pressure oil pump is designed for ZF’s WG series powershift transmissions. It is a direct fit for the WG 258 Series, WG 260 Series, WG 261 Series, WG 308 Series, WG 310 Series, and WG 311 Series. These models are commonly found in construction equipment, material handlers, and agricultural machinery. Always verify your transmission’s serial number to confirm fitment, as variations exist between early and late production runs.
During installation, the pump mounts directly to the 4646101156: TRANSMISSION HOUSING and is secured using 0636015304: HEXAGON SCREW fasteners. The pump’s outlet port aligns with the 4646301327: HOUSING that directs oil to the valve body. For proper torque retention, use 0636101828: CAP SCREW hardware on the mounting flange.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4646101156 | TRANSMISSION HOUSING | Encloses and supports the gear train and pump assembly |
| 4646301327 | HOUSING | Directs oil flow from pump to valve body passages |
| 0636015304 | HEXAGON SCREW | Secures pump and housing components with precise torque |
| 0636101828 | CAP SCREW | Fastens pump mounting flange to transmission case |
| 4646301102 | COVER SHEET | Seals the pump cavity to prevent debris ingress |
| 4646301285 | COVER SHEET | Alternate gasket for pump housing interface |
| 0730365190 | TYPE PLATE | Identification tag for transmission model and serial number |
| 0631311009 | GROOVED STUD | Alignment dowel for pump-to-housing positioning |
| 0636101193 | CAP SCREW | Secondary fastener for pump cover retention |
| 0636010179 | HEXAGON SCREW | Mounting bolt for auxiliary pump brackets |
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