Overview
The ZF 4644.121.428 OIL PIPE is a precision-engineered fluid conduit designed for the lubrication and cooling circuits within ZF WG150, WG200, and WG201 series transmissions. This OEM genuine part channels pressurized transmission fluid directly to critical bearing assemblies and gear meshes, ensuring consistent thermal regulation and friction reduction during high-torque operations. The SKU 4644.121.428 is manufactured to exact factory tolerances, making it a direct replacement for worn or damaged oil lines in heavy-duty industrial drivetrains. When installed alongside a 4642101109: TRANSMISSION HOUSING or a 4642301205: TRANSMISSION HOUSING, this pipe maintains the sealed hydraulic integrity required for sustained performance.
Symptoms of Failure
- External transmission fluid seepage: A cracked or corroded 4644.121.428 oil pipe will produce visible oil drips near the bell housing or mid-plate area, often mistaken for a pan gasket leak.
- Delayed or harsh gear engagement: Insufficient lubrication pressure caused by a restricted or leaking pipe leads to clutch pack chatter and sluggish shifts under load.
- Overheating transmission sump: When the oil pipe fails to deliver adequate flow to the cooler circuit, operating temperatures rise rapidly, triggering warning lights on industrial equipment.
- Metallic debris in fluid: A collapsed internal oil pipe can starve bearings of lubrication, producing fine metal particles visible during routine fluid sampling.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4644.121.428 |
| Material | Seamless drawn steel with zinc-nickel plating |
| Overall Length | 385 mm (estimated) |
| Tube Outer Diameter | 12 mm |
| Wall Thickness | 1.5 mm |
| Weight | 0.34 kg |
| OEM Reference | ZF 4644.121.428 |
| Seal Type | O-ring boss with flared end |
Compatibility
This oil pipe is specifically engineered for ZF WG-series powershift transmissions. Verified fitment includes the WG150, WG200, and WG201 models commonly found in mobile cranes, forklifts, and construction loaders. It also serves as a service replacement for earlier WG180 variants when paired with the correct 0631311009: GROOVED STUD and 0730365125: TYPE PLATE for identification. Always verify the routing path against your transmission’s housing casting number before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4642101109 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4642301205 | TRANSMISSION HOUSING | Alternate housing for WG200 series |
| 0730365125 | TYPE PLATE | Identification tag for transmission model |
| 0631311009 | GROOVED STUD | Fastener for oil pipe retention |
| 4642301168 | SCREEN SHEET | Filter mesh for oil intake |
| 4642301169 | SCREEN SHEET | Fine filtration screen |
| 0636100621 | HEXAGON SCREW | Mounting bolt for cover plates |
| 4642301186 | SCREEN SHEET | High-flow filter element |
| 4644106300 | SHIFT SYSTEM | Hydraulic valve assembly |
| 4644306500 | COVER PLATE | Access cover for valve body |
