Overview
The ZF 4699.025.173 GP25 is a genuine OEM gear pump assembly engineered for high-pressure hydraulic circuits within ZF construction machinery transmissions. This critical component generates the oil flow necessary for clutch engagement, lubrication, and cooling inside the transmission housing. As a direct replacement unit, the SKU 4699.025.173 ensures precise volumetric output and pressure stability. The GP25 pump mounts directly to the transmission housing, drawing fluid from the sump and delivering it through internal galleries. When paired with a properly sealed HOUSING (4699101153) and a secure CAP SCREW (0636101411), this assembly maintains the integrity of the entire hydraulic loop.
Symptoms of Failure
- Intermittent gear slipping under load: When the GP25 pump loses internal clearance, hydraulic pressure drops, causing clutch packs to slip during heavy digging or lifting operations.
- Whining or cavitation noise from the transmission: Worn gears or a damaged HOUSING COVER (4699309121) can allow air ingestion, producing a distinct high-pitched whine that worsens at higher RPM.
- Visible oil seepage around the pump mounting flange: Degraded seals or a cracked HOUSING (4699301250) often lead to external leaks, leaving oil residue on the bell housing.
- Delayed engagement when shifting gears: Reduced pump output extends the time required to build clutch pressure, resulting in sluggish or jerky shifts.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number / SKU | 4699.025.173 (GP25) |
| Type | Gear Pump, Fixed Displacement |
| Displacement (est.) | 25 cc/rev |
| Maximum Pressure (est.) | 25 bar (362 psi) |
| Material | Hardened Steel Gears, Aluminum Housing |
| Weight (approx.) | 4.2 kg (9.3 lbs) |
| OEM Reference | ZF 4699.025.173 |
| Mounting Torque (CAP SCREW) | 55 Nm (use 0636101411) |
Compatibility
This GP25 pump is primarily used in ZF WG180, WG200, and WG210 series powershift transmissions found in wheel loaders, telehandlers, and graders. It also fits select 4WG-200 and 6WG-200 variants. Always verify the pump drive tang and flange pattern against your existing unit. The pump interfaces with the HOUSING (4699101153) and requires the correct CAP SCREW (0636101411) for secure installation. For complete sealing, inspect the HOUSING (4699301250) and HOUSING COVER (4699309121) for wear during replacement.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4699101153 | HOUSING | Main pump mounting body |
| 4699301250 | HOUSING | Intermediate pump support |
| 4699309121 | HOUSING COVER | Seals pump cavity |
| 0636101411 | CAP SCREW | Fastener for housing |
| 0631302072 | CYLINDRICAL PIN | Alignment dowel |
| 0636302013 | SCREW PLUG | Port sealing plug |
| 0501331653 | SCREW PLUG | Pressure port plug |
| 0634801038 | SEALING RING | O-ring for plugs |
| 0637885613 | BREATHER | Ventilation valve |
| 0769100082 | TYPE PLATE | Identification label |
