ZF 4699.823.071 GP21 | OEM Genuine Part

Overview

The ZF 4699.823.071 GP21 is a precision-engineered gear pump assembly designed for high-pressure hydraulic circuits within ZF heavy-duty transmissions. This OEM genuine part, identified by SKU 4699.823.071, is responsible for generating the lubrication and clutch actuation pressure required for smooth power delivery in construction machinery. Mounted directly to the transmission housing, it draws fluid from the sump and delivers it to critical components such as the BASIC PARTS assembly and the HOUSING unit. Without a properly functioning GP21 pump, the entire drivetrain loses its ability to maintain consistent torque flow.

Symptoms of Failure

• Low hydraulic pressure at idle – A worn GP21 pump often fails to build adequate pressure when the engine is at low RPM, causing delayed clutch engagement and sluggish machine response.
• Intermittent gear slipping under load – As internal clearances increase, the pump cannot maintain volume, leading to momentary loss of drive power when excavating or pushing heavy loads.
• Whining or cavitation noise from the transmission – Air ingestion due to a worn pump seal creates a distinct high-pitched whine, often accompanied by erratic shifting patterns.
• Visible oil leaks around the pump mounting flange – Deteriorated O-rings or housing cracks allow transmission fluid to escape, resulting in low sump levels and eventual overheating.

Technical Specifications

Compatibility

This GP21 pump is primarily utilized in ZF’s WG series powershift transmissions, including the WG180, WG200, and WG210 models commonly found in wheel loaders, graders, and compactors. It also appears in certain ZF 4WG-200 and 6WG-250 variants used in mid-size construction machinery. When replacing the pump, it is recommended to inspect the WHEEL SHAFT for spline wear and the PLANET CARRIER for bearing damage, as debris from a failing pump can migrate into these assemblies.

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