Overview
The ZF 4143.020.250 2 HL 250 Hydrostatic Drive Assembly is a complete, pre-assembled unit engineered for demanding industrial driveline applications. This component serves as the primary hydraulic power transfer module within the ZF HL 100 and HL 270 series transmissions, converting engine torque into infinitely variable hydrostatic output for precise vehicle speed control. The SKU 4143.020.250 integrates a variable displacement pump and fixed motor in a single housing, ensuring seamless power delivery in wheel loaders, telehandlers, and agricultural machinery. For proper sealing and structural integrity, this assembly mates directly with the 4143101043: HOUSING and the 4143301055: HOUSING, which form the outer casing of the transmission.
Symptoms of Failure
When the ZF 4143.020.250 hydrostatic drive assembly begins to degrade, operators typically notice three distinct failure modes. 1. Hydrostatic whining or cavitation noise during acceleration indicates internal pump wear or low charge pressure, often accompanied by erratic machine movement. 2. Chronic oil leaks at the drive shaft seal are a common long-tail search issue, resulting from degraded elastomers inside the assembly. 3. Loss of high-speed traction or inability to reach full travel speed under load points to slipping pistons or worn valve plates. 4. Overheating of the transmission fluid without external cause suggests internal bypassing within the 2 HL 250 unit, requiring immediate inspection of the 4143298040: CASE for cracks.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number / SKU | 4143.020.250 |
| Assembly Type | 2 HL 250 Hydrostatic Drive (Complete Unit) |
| OEM Reference | ZF 2 HL 250 Series |
| Housing Material | High-Grade Aluminum Alloy (Die-Cast) |
| Dry Weight | Approx. 42 kg (92.6 lbs) |
| Overall Length | 385 mm |
| Overall Width | 280 mm |
| Overall Height | 310 mm |
| Max Operating Pressure | 420 bar (6,090 psi) |
| Max Input Speed | 3,000 RPM |
| Displacement (Pump) | Variable, 0–55 cm³/rev |
| Sealing System | Integrated O-Ring & Cap Screw Assembly |
Compatibility
This complete hydrostatic drive unit is designed for ZF transmissions in the HL 100 and HL 270 series families. It is a direct fit for the following ZF transmission models: WG180, WG200, WG210, WG220, and WG250. The 4143.020.250 assembly also shares mounting interfaces with the 0631329135: SPRING PIN, which secures the control linkage within the transmission housing. Always verify your transmission serial number against the HL 250 specification before ordering.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4143101043 | HOUSING | Outer casing for hydrostatic assembly |
| 4143301055 | HOUSING | Secondary housing for valve body |
| 4143298040 | CASE | Main structural case for gear train |
| 0631329135 | SPRING PIN | Secures control lever pivot |
| 0501214034 | SEALING CAP | Seals hydraulic port openings |
| 0636101024 | CAP SCREW | Fastens housing sections together |
| 4475280099 | SCREW PLUG | Closes drain or test ports |
| 0634303266 | O-RING | Provides static seal between flanges |
| 4143301045 | SCREEN SHEET | Filters debris from hydraulic fluid |
| 0636420051 | COUNTERSUNK SCREW | Mounts screen sheet to housing |
