Overview
The ZF 4651.137.003 EMERGENCY STEERING PUMP is a critical hydraulic component engineered specifically for the WG 100 Series transmission family. This OEM genuine part ensures that steering control remains operational even in the event of a primary pump failure, providing a fail-safe mechanism for heavy-duty industrial vehicles. Positioned within the transmission’s auxiliary hydraulic circuit, the emergency steering pump (SKU: 4651.137.003) draws fluid from the TRANSMISSION HOUSING to maintain steering pressure. Its robust design integrates seamlessly with the HOUSING assembly, ensuring reliable performance under extreme loads. This part is indispensable for operators requiring uninterrupted steering capability in demanding environments.
Symptoms of Failure
- Steering wheel becomes stiff or unresponsive — A worn emergency steering pump reduces hydraulic pressure, making steering difficult, especially at low speeds or during sudden maneuvers.
- Audible whining or grinding noise from the transmission — Internal bearing wear or cavitation within the pump produces high-pitched sounds, indicating imminent failure.
- Hydraulic fluid leaks near the pump mounting point — Degraded seals or cracks in the pump housing cause oil seepage, often visible around the O-RING interface.
- Intermittent loss of steering assist during operation — A failing pump may deliver inconsistent flow, leading to sudden drops in steering response, particularly when turning sharply.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number | 4651.137.003 |
| OEM Reference | ZF 4651.137.003 |
| Material | High-strength aluminum alloy with steel internals |
| Weight | 2.8 kg (6.2 lbs) |
| Dimensions (L x W x H) | 180 mm x 120 mm x 95 mm |
| Operating Pressure | Up to 180 bar |
| Fluid Compatibility | ZF-approved hydraulic oils (ISO VG 46) |
| Mounting Type | Flange-mounted with four bolt holes |
Compatibility
This emergency steering pump is primarily designed for the ZF WG 100 Series, but it also fits select models within the broader WG family due to shared hydraulic architectures. Compatible transmissions include:
- ZF WG 100
- ZF WG 120
- ZF WG 150
- ZF WG 180
- ZF WG 200
Always verify fitment with your specific transmission serial number. The pump interfaces directly with the HOUSING and requires proper sealing using the included O-ring to prevent fluid loss.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4651101007 | TRANSMISSION HOUSING | Encloses and supports transmission gears and shafts |
| 4651301029 | HOUSING | Provides mounting surface for auxiliary pumps |
| 0634303928 | O-RING | Seals pump-to-housing connection |
| 4651301024 | HOUSING | Secondary housing for hydraulic valve assembly |
| 4651203002 | SCREEN SHEET | Filters debris from hydraulic fluid intake |
| 4651303005 | SCREEN SHEET | Fine mesh filter for high-pressure circuits |
| 0636101032 | CAP SCREW | Secures pump mounting flange |
| 0630361028 | SEALING CAP | Protects unused hydraulic ports |
| 4475280060 | SCREW PLUG | Closes pressure test points |
| 0634303312 | O-RING | Seals screw plug connections |
