Overview
The ZF 4166.232.026 CIRCUIT COVER is a precision-engineered sealing component designed for the valve body and hydraulic control assembly within ZF WG180 and WG200 series transmissions. This OEM genuine part, identified by SKU 4166.232.026, serves as a protective and pressure-retaining barrier over critical fluid passages, ensuring that hydraulic circuits maintain proper pressure for clutch engagement and gear shifts. Mounted directly onto the TRANSMISSION HOUSING, this cover prevents contamination ingress and fluid bypass, directly supporting the integrity of the entire hydraulic system. Without a properly sealed circuit cover, the transmission cannot sustain the precise oil flow required for smooth power delivery.
Symptoms of Failure
When the ZF 4166.232.026 CIRCUIT COVER degrades or becomes damaged, operators typically encounter these specific failure indicators:
- External oil seepage around the valve body area: A cracked or warped circuit cover allows transmission fluid to escape, often visible as wet spots on the TRANSMISSION HOUSING near the control module.
- Erratic or delayed gear engagement: Loss of hydraulic pressure due to a compromised cover leads to soft shifts or hesitation when selecting forward or reverse gears.
- Persistent low transmission fluid level without visible pan leaks: Fluid escapes through micro-fractures in the cover, causing gradual depletion that mimics internal seal failure.
- Overheating in the WG180/WG200 series: Insufficient circuit pressure forces the transmission to slip, generating excess heat that can trigger warning lights or thermal shutdown.
Technical Specifications
| Specification | Detail |
|---|---|
| OEM Part Number | 4166.232.026 |
| Material | Die-cast aluminum alloy with corrosion-resistant coating |
| Overall Dimensions (approx.) | 180 mm x 120 mm x 25 mm |
| Weight | 0.85 kg (1.87 lbs) |
| Mounting Interface | 6 bolt holes (accepts HEXAGON SCREW fasteners) |
| Sealing Surface | Machined flat with O-ring groove (uses O-RING 0634303485) |
| Operating Temperature Range | -40°C to +120°C |
Compatibility
This circuit cover is engineered exclusively for ZF WG180 and WG200 series powershift transmissions. It is a direct fit for models including WG180, WG200, and their sub-variants used in construction, agricultural, and material handling equipment. The part interfaces with the DISCONNECTION assembly and the OUTPUT FLANGE housing, forming a sealed unit that directs hydraulic flow to the clutch packs. Always verify your transmission serial number against the WG180/WG200 series to ensure correct fitment.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644105475 | DISCONNECTION | Hydraulic clutch disconnect valve assembly |
| 4642303097 | OUTPUT FLANGE | Output shaft connection flange |
| 0636020211 | HEXAGON SCREW | Fastener for circuit cover mounting |
| 4644101134 | TRANSMISSION HOUSING | Main structural housing assembly |
| 4644301349 | HOUSING | Secondary housing for valve body |
| 0730365125 | TYPE PLATE | Identification and specification plate |
| 0631311009 | GROOVED STUD | Alignment and retention stud |
| 0636305019 | SCREW PLUG | Hydraulic port sealing plug |
| 4644301247 | THREADED BUSH | Threaded insert for housing |
| 0634303485 | O-RING | Seal between cover and housing |
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