Overview
The ZF 4699.804.116 GK25 II is a genuine OEM gearshift mechanism designed for the power take-off (PTO) section of heavy-duty ZF transmissions. This component serves as the primary actuation unit, engaging and disengaging the PTO clutch to transfer engine torque to auxiliary hydraulic pumps on construction machinery such as wheel loaders and excavators. The SKU 4699.804.116 is a direct replacement for the original factory-installed part, ensuring precise shift timing and full mechanical interlock with the transmission’s main drive. It sits between the 4699101124: HOUSING and the 4699102132: INPUT shaft assembly, forming the critical control interface for auxiliary power delivery.
Symptoms of Failure
- Intermittent PTO engagement failure – The gearshift mechanism fails to lock into position, causing the PTO to disengage under load. This is often reported as “PTO won’t stay engaged” in ZF WG180 and WG200 transmissions.
- Hydraulic oil seepage at shift shaft seal – Worn internal O-rings or housing cracks allow transmission fluid to leak past the shift rod, leaving puddles under the bell housing. Search queries like “ZF transmission oil leak at shift shaft” commonly point to this part.
- Grinding noise during PTO activation – Damaged shift forks or worn detent springs cause incomplete clutch engagement, producing a metallic grinding sound when the PTO is engaged under partial load.
- Stiff or stuck shift lever operation – Corrosion or debris buildup in the GK25 II mechanism prevents smooth movement, requiring excessive force to shift the PTO in or out of gear.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number (SKU) | 4699.804.116 |
| OEM Reference | GK25 II |
| Material | Case-hardened steel body with nitrile seals |
| Weight | 1.8 kg (4.0 lbs) |
| Overall Length | 215 mm |
| Shift Travel | 28 mm |
| Max Operating Pressure | 25 bar (362 psi) |
| Temperature Range | -20°C to +120°C |
Compatibility
This 4699.804.116 gearshift mechanism is engineered for ZF’s WG series powershift transmissions, specifically the WG180, WG200, and WG250 models used in construction machinery. It is also compatible with the ZF 4WG-200 and ZF 6WG-250 series. When replacing this unit, always inspect the mating 4699103026: OUTPUT shaft for wear, as misalignment can accelerate failure of the GK25 II assembly.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4699004116 | GK25 II | Gearshift mechanism (alternative variant) |
| 4699101124 | HOUSING | Encloses shift fork and detent assembly |
| 4699102132 | INPUT | Input shaft coupling to PTO clutch |
| 4699103026 | OUTPUT | Output shaft for auxiliary pump drive |
| 4699105107 | TURNTABLE BEARING | Rotary support for shift mechanism |
| 4699301209 | HOUSING | Secondary housing for PTO section |
| 4699301015 | HOUSING COVER | Seals the top of the shift housing |
| 4699301085 | COVER | Protective cover for shift rod access |
| 4699301014 | THREAD PROTECTIVE SHIELD | Prevents thread damage during installation |
| 0634303980 | O-RING | Seals shift shaft bore against leaks |
