Overview
The ZF 4616.123.021 INTERM.GEARBOX is a critical intermediate gearbox assembly designed for the WG 65 Series of heavy-duty transmissions. This OEM genuine part serves as the central power distribution hub within the transmission housing, transferring rotational force between the input shaft and the output planetary sets. Positioned directly within the main gear case, the 4616.123.021 ensures precise gear meshing and torque management under extreme load conditions. When installed alongside a TRANSMISSION HOUSING, this intermediate gearbox maintains the structural integrity of the drivetrain, preventing misalignment and reducing vibration. The SKU 4616.123.021 is engineered to ZF’s exacting tolerances, making it a direct replacement for worn units in WG65 applications.
Symptoms of Failure
- Whining or grinding noise during gear shifts: A worn intermediate gearbox often produces a high-pitched whine or metallic grinding sound, especially when the transmission is under load. This indicates bearing wear or gear tooth damage inside the 4616.123.021 assembly.
- Intermittent gear slipping under heavy torque: If the intermediate gearbox loses its precise engagement, operators may experience sudden gear slippage or hesitation during acceleration, particularly in off-road or construction equipment.
- Oil leaks around the transmission housing: Degraded seals within the intermediate gearbox can cause transmission fluid to weep from the joint between the gearbox and the HEXAGON SCREW mounting points, leading to low fluid levels and overheating.
- Excessive backlash or driveline vibration: As the internal gears wear, the intermediate gearbox may develop excessive play, causing noticeable vibration through the chassis and driveline during operation.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4616.123.021 |
| Product Type | Intermediate Gearbox Assembly |
| Material | Case-hardened alloy steel (gears); cast iron housing |
| Weight | Approx. 18.5 kg (40.8 lbs) |
| Overall Length | 245 mm |
| Overall Width | 185 mm |
| Overall Height | 210 mm |
| OEM Reference | ZF 4616.123.021 (Genuine) |
| Mounting Hardware | Requires HEXAGON SCREW (M10x35) and HEXAGON SCREW (M12x40) |
| Sealing Components | O-RING (0634313118) and SEALING RING (0634801152) |
Compatibility
This intermediate gearbox is specifically engineered for the ZF WG 65 Series transmissions, including models such as the WG65, WG80, and WG100. It is also compatible with select WG120 and WG150 variants that share the same intermediate shaft configuration. The 4616.123.021 is not interchangeable with WG180 or WG200 series units due to differences in gear ratios and housing dimensions. For proper installation, always pair this part with the correct HEXAGON SCREW fasteners and verify alignment with the CYLINDRICAL PIN (0631306085) for precise positioning.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4616101065 | TRANSMISSION HOUSING | Main structural case for gearbox assembly |
| 0636011038 | HEXAGON SCREW | Fastener for mounting intermediate gearbox |
| 0636011118 | HEXAGON SCREW | Secondary mounting bolt for gearbox |
| 0636016015 | HEXAGON SCREW | Heavy-duty fastener for housing |
| 0631306085 | CYLINDRICAL PIN | Alignment pin for gearbox positioning |
| 0634313118 | O-RING | Seal between gearbox and housing |
| 0636304019 | SCREW PLUG | Oil drain/fill port plug |
| 0634801152 | SEALING RING | Gasket for fluid containment |
| 0732611049 | FILTER INSERT | Hydraulic fluid filtration element |
| 0634303718 | O-RING | Secondary seal for filter housing |
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