ZF 4699.804.019 GK25 | OEM Genuine Part

Overview

The ZF 4699.804.019 GK25 is a critical OEM genuine component engineered for the internal valve body assembly within ZF heavy-duty powershift transmissions. This part functions as a precision-machined spool or shuttle element, directing hydraulic fluid pressure to engage specific clutch packs during gear selection. Positioned directly within the main control housing, the GK25 ensures smooth, reliable shifting under extreme load conditions common in construction machinery. The SKU 4699.804.019 is manufactured to ZF’s original tolerances, guaranteeing a direct replacement without modification. When installed alongside the 4699101043 HOUSING and the 4699301106 HOUSING, this part restores factory-spec hydraulic circuit integrity.

Symptoms of Failure

• Delayed or harsh gear engagement: A worn 4699.804.019 GK25 can cause noticeable lag when shifting from neutral to forward or reverse, often accompanied by a jarring clunk as pressure builds unevenly.
• Intermittent transmission slipping under load: When the spool valve fails to seal properly, hydraulic pressure bleeds off, causing the transmission to slip during uphill climbs or heavy digging operations.
• Erratic shift patterns or stuck gears: Debris or wear on this part may prevent the valve from returning to its neutral position, resulting in the transmission staying in one gear or skipping shifts unpredictably.
• Contaminated hydraulic fluid with metallic particles: Internal wear of the GK25 generates fine metal shavings that circulate through the system, accelerating damage to seals and the 4699301015 HOUSING COVER.

Technical Specifications

Compatibility

This GK25 valve spool is designed for use in ZF WG series powershift transmissions commonly deployed in wheel loaders, dozers, and excavators. It is a direct fit for the ZF WG180, WG200, and WG210 models. The part also integrates with the ZF 4WG-200 and 6WG-200 variants. For proper sealing and alignment, ensure the mating 4699301085 COVER is inspected for wear during installation.

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