Overview
The ZF 4644.105.002 DISCONNECTION is a critical OEM genuine component engineered for the WG 200 series transmissions. This part functions as the primary clutch disengagement mechanism, allowing the operator to smoothly separate the engine from the drivetrain during gear shifts or stationary operation. Located within the transmission’s hydraulic control circuit, the disconnection valve (SKU: 4644.105.002) modulates oil pressure to engage and release the clutch packs. Without this precision-machined part, the transmission cannot properly transition between forward, neutral, and reverse modes. It is often replaced in conjunction with the 4644105413: DISCONNECTION unit to ensure complete hydraulic integrity.
Symptoms of Failure
- Delayed or harsh gear engagement: When the 4644.105.002 wears, you may experience a noticeable lag when shifting from neutral to drive, or a jarring “clunk” as the clutch engages.
- Transmission overheating under load: A failing disconnection valve can cause partial clutch drag, generating excessive heat in the WG200 and leading to premature fluid degradation.
- Intermittent loss of forward or reverse: Worn internal seals within this part allow hydraulic pressure to bleed off, causing the transmission to suddenly slip out of gear during operation.
- Oil contamination from metallic debris: As the disconnection mechanism degrades, small metal particles can enter the fluid, often visible on the dipstick or during filter changes.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number (SKU) | 4644.105.002 |
| OEM Reference | ZF 4644.105.002 |
| Material | Hardened steel body with nitrile seals |
| Weight | 0.85 kg (1.87 lbs) |
| Overall Length | 142 mm |
| Bore Diameter | 28 mm |
| Operating Pressure | 12–18 bar |
| Temperature Range | -20°C to +120°C |
Compatibility
This genuine ZF disconnection component is primarily designed for the WG 200 Series transmissions, including models such as the WG180, WG200, and WG210. It is also compatible with certain WG 150 variants that share the same hydraulic valve body architecture. The part interfaces directly with the 4642303093: OUTPUT FLANGE and is secured using the 0636021010: HEXAGON SCREW. For full assembly, ensure the 4644101040: TRANSMISSION HOUSING is free of cracks or warping before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644105413 | DISCONNECTION | Secondary clutch disengagement valve |
| 4642303093 | OUTPUT FLANGE | Transfers torque to driveshaft |
| 0636021010 | HEXAGON SCREW | Fastens disconnection assembly |
| 4644101040 | TRANSMISSION HOUSING | Main structural casing |
| 4644301197 | TRANSMISSION HOUSING | Alternate housing variant |
| 0730365067 | TYPE PLATE | Identification and serial tag |
| 0631311009 | GROOVED STUD | Alignment dowel for housing |
| 0636015073 | HEXAGON SCREW | Mounting bolt for valve body |
| 0634801250 | SEALING RING | Prevents fluid leaks at joints |
| 0636305026 | SCREW PLUG | Closes hydraulic test ports |
