Overview
The ZF 4143.020.136 2 HL 270 Hydrostatic Drive Assembly is a complete, fully assembled unit designed for the HL 100 and HL 270 series transmissions. This assembly serves as the primary hydraulic power transfer module, converting engine torque into infinitely variable speed output for demanding mobile machinery. As a critical component within the transmission housing, it integrates the axial piston pump and motor into a single sealed package. The SKU 4143.020.136 is a direct OEM replacement, ensuring precise fitment and hydraulic performance. When servicing this unit, technicians often inspect the adjacent 4143101050: HOUSING and 4143301055: HOUSING for wear, as these components seal the drive assembly against contamination.
Symptoms of Failure
- Hydrostatic drive slipping under load: A worn 4143.020.136 unit often fails to maintain pressure, causing the vehicle to lose power when climbing grades or carrying heavy loads.
- External oil leaks from the drive assembly: Deteriorated seals or a cracked 4143298040: CASE can lead to visible hydraulic fluid weeping around the unit, resulting in low oil levels and erratic operation.
- Excessive noise or whining during operation: Internal bearing or piston wear produces a high-pitched whine that increases with engine RPM, indicating imminent failure of the hydrostatic drive.
- Inconsistent or jerky speed control: A failing assembly may cause sudden surges or hesitation when the operator adjusts the throttle, due to internal valve or swash plate degradation.
Technical Specifications
| Part Number | 4143.020.136 |
| Assembly Type | 2 HL 270 Hydrostatic Drive (Complete Unit) |
| Weight | Approx. 48 kg (106 lbs) |
| Material | High-strength cast iron housing with hardened steel internals |
| Dimensions (L x W x H) | 420 mm x 320 mm x 280 mm |
| OEM Reference | ZF 4143.020.136 |
| Fluid Type | ZF TE-ML 03C or equivalent HLP 46 hydraulic oil |
| Max Operating Pressure | 420 bar (6,090 psi) |
Compatibility
This hydrostatic drive assembly is engineered for ZF transmissions in the HL 100 and HL 270 series. It is a direct fit for models including the WG180, WG200, WG210, and WG220. The unit also integrates with earlier HL 250 and HL 260 variants where the mounting pattern matches. For proper installation, ensure the 0631329135: SPRING PIN is correctly aligned to lock the drive shaft to the transmission input. This assembly is not backward compatible with the HL 80 series without adapter plates.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4143101050 | HOUSING | Encloses the hydrostatic drive assembly |
| 4143301055 | HOUSING | Secondary housing for bearing support |
| 4143298040 | CASE | Outer casing for the drive unit |
| 0631329135 | SPRING PIN | Locks shaft alignment during assembly |
| 0636101024 | CAP SCREW | Secures housing halves together |
| 4475280099 | SCREW PLUG | Seals hydraulic ports |
| 0634303266 | O-RING | Prevents fluid leaks at joints |
| 0501200072 | VENT VALVE | Relieves internal pressure buildup |
| 0501217673 | LUBRICATING NIPPLE | Grease point for bearing maintenance |
| 0636302031 | SCREW PLUG | Drain or fill plug for the assembly |
