ZF 4699.026.001 GP23 | OEM Genuine Part

Overview

The ZF 4699.026.001 GP23 is a genuine OEM gear pump assembly engineered for high-pressure hydraulic circuits within ZF powershift transmissions used in construction machinery. This component delivers precise oil flow to actuate clutch packs and lubrication circuits, ensuring consistent shift quality under heavy loads. The SKU 4699.026.001 mounts directly to the transmission housing and interfaces with the torque converter circuit. When paired with a properly sealed HOUSING (4699101053) and a matching HOUSING (4699301126), this pump maintains stable pressure across all operating temperatures. A worn GP23 unit directly compromises hydraulic response, making early diagnosis critical for avoiding drivetrain downtime.

Symptoms of Failure

• Delayed engagement or gear slipping under load — When the GP23 loses volumetric efficiency, clutch packs receive insufficient pressure, causing hesitation when shifting from neutral to forward or reverse. This is a common long-tail search query for “ZF transmission slow engagement construction equipment.”
• Erratic or low hydraulic pressure readings — Operators may notice pressure gauge fluctuations below 150 psi at idle. A failing 4699.026.001 often produces whining noises as cavitation occurs, especially after cold starts.
• External oil seepage from pump mounting flange — Worn seals allow hydraulic fluid to escape past the pump body. Inspect the area around the SEALING RING (0634801038) and the SCREW PLUG (0501319149) for wet spots, as these are common leak points.
• Overheating transmission fluid — Reduced pump output forces the torque converter to work harder, generating excess heat. This symptom often appears alongside burnt-smelling fluid in severe cases.

Technical Specifications

Compatibility

This genuine ZF GP23 pump is designed for the WG180, WG200, and WG210 series powershift transmissions commonly found in wheel loaders, dozers, and telehandlers from manufacturers such as Caterpillar, Volvo, and Liebherr. It also fits select 4WG-200 and 6WG-200 variants used in medium-duty construction machinery. Always verify the pump drive tang and housing bolt pattern against your existing unit. For complete transmission rebuilds, consider inspecting the BREATHER (0637885613) and CYLINDRICAL PIN (0631302212) to ensure proper ventilation and alignment during reassembly.

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