Overview
The ZF 4651.004.023 4 WG 100(500) Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway machinery. This assembly integrates the clutch pack, planetary gearsets, and hydraulic control components into a single, ready-to-install package. As a core element of the WG 100 series, it manages torque distribution across four forward speeds and one reverse speed. The SKU 4651.004.023 is specifically calibrated for 500 Nm input torque applications, ensuring precise shift timing under load. It sits between the torque converter and the final drive housing, directly interfacing with the TRANSMISSION HOUSING to form the main structural backbone of the gearbox.
Symptoms of Failure
- Delayed or harsh engagement when shifting from neutral to forward or reverse, often accompanied by a loud clunk. This indicates worn clutch discs or piston seals within the assembly.
- Intermittent gear slipping under load, particularly in 3rd or 4th gear, where the transmission momentarily loses power before re-engaging. This points to hydraulic pressure loss inside the 4651.004.023 unit.
- External oil seepage at the bell housing joint, caused by degraded sealing surfaces where the assembly mates with the HOUSING. Look for wet spots around the lower bolt circle.
- Erratic shift patterns or no reverse, often resulting from a cracked clutch drum or broken snap rings inside the complete unit. This requires immediate replacement of the assembly.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4651.004.023 |
| Assembly Type | Complete Powershift Unit (4 WG 100/500) |
| Input Torque Capacity | 500 Nm (369 lb-ft) |
| Weight (approx.) | 68 kg (150 lbs) |
| Housing Material | Cast Iron (GGG-40) |
| Seal Material | Nitrile Rubber (NBR) |
| OEM Reference | ZF 4651.004.023 / 4WG100 |
| Overall Length | 420 mm |
| Bolt Pattern | 6x M12 on 180 mm PCD |
Compatibility
This complete unit is engineered for the ZF WG 100 series, specifically the 4 WG 100(500) variant. It is also compatible with the WG 180 and WG 200 series when used with the appropriate HOUSING adapter kit. The assembly directly replaces units in ZF 4WG-100, 4WG-180, and 4WG-200 transmissions found in loaders, graders, and telescopic handlers. Always verify the input flange and bell housing pattern before installation. The unit requires a new O-RING at the main seal interface to prevent fluid bypass during reassembly.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4651101007 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4651301029 | HOUSING | Intermediate housing for clutch pack |
| 0634303928 | O-RING | Seals housing-to-assembly joint |
| 4651301024 | HOUSING | Adapter housing for WG 180/200 |
| 4651203002 | SCREEN SHEET | Oil filter screen for hydraulic circuit |
| 4651303005 | SCREEN SHEET | Secondary fine-mesh filter screen |
| 0636101032 | CAP SCREW | M12 bolt for housing attachment |
| 0630361028 | SEALING CAP | Plugs unused hydraulic ports |
| 4475280060 | SCREW PLUG | Drain plug for oil pan |
| 0634303312 | O-RING | Seals screw plug and cap screw |
