Overview
The ZF 4108.122.020 HYDRAULIC MOTOR is a critical OEM genuine component engineered for high-torque applications within ZF construction machinery transmissions. This motor converts hydraulic pressure into mechanical rotational force, directly driving the transmission’s output shaft. As a precision-machined unit, the SKU 4108.122.020 sits within the hydraulic circuit, regulating fluid flow to enable smooth gear engagement and load handling. Its robust construction ensures reliable power delivery in excavators, wheel loaders, and graders, making it indispensable for maintaining operational uptime in demanding job sites.
Symptoms of Failure
- Hydraulic motor oil leaks – Visible fluid seepage around the motor housing or shaft seal indicates worn internal seals, leading to pressure loss and reduced efficiency.
- Transmission gear slipping under load – A failing 4108.122.020 motor cannot maintain consistent hydraulic pressure, causing intermittent power loss or hesitation during heavy lifting.
- Unusual whining or grinding noises – Internal bearing wear or cavitation from degraded motor components produces audible sounds, especially at low speeds or during cold starts.
- Erratic machine movement – Inconsistent hydraulic flow results in jerky or delayed responses when operating the transmission, often mistaken for control valve issues.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4108.122.020 |
| Type | Hydraulic Motor (Axial Piston) |
| Material | High-strength cast iron housing, hardened steel internals |
| Weight | Approx. 12.5 kg (27.6 lbs) |
| Dimensions (L x W x H) | 280 mm x 160 mm x 140 mm |
| OEM Reference | ZF 4108.122.020 |
| Max Operating Pressure | 350 bar (5,076 psi) |
| Displacement | 45 cc/rev |
Compatibility
This hydraulic motor is designed for integration with ZF WG180, WG200, and WG210 series transmissions commonly found in construction machinery. It also fits select WG160 and WG250 models where hydraulic motor mounting patterns align. The 4108.122.020 replaces earlier revisions (e.g., 4108.122.010) and is backward-compatible with most ZF power shift transmissions produced after 2005. Always verify the transmission serial number before installation.
During replacement, ensure the 4108101093 HOUSING and 4108201177 HOUSING are inspected for cracks or wear, as they directly support the motor assembly. The 0501313402 DRAIN VALVE must be replaced to prevent fluid contamination, while the 0636302056 SCREW PLUG ensures a leak-free seal during reinstallation. These components work in concert to maintain hydraulic integrity.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4108101093 | HOUSING | Encloses the motor assembly; provides structural support |
| 4108201177 | HOUSING | Secondary housing for hydraulic fluid routing |
| 0501313402 | DRAIN VALVE | Allows controlled fluid drainage during maintenance |
| 0636302056 | SCREW PLUG | Seals hydraulic ports; prevents leaks |
| 4108301304 | BEARING COVER | Protects motor bearings from debris |
| 4108306173 | GASKET | Creates a leak-proof seal between components |
| 0750110040 | SHAFT SEAL | Prevents fluid escape along the motor shaft |
| 4108111051 | POWER TAKE-OFF | Transfers power to auxiliary equipment |
| 0730106757 | WASHER | Distributes load under fasteners |
| 0730106758 | WASHER | Provides spacing and vibration dampening |
