Overview
The ZF 0634.402.526 R-RING is a precision-engineered sealing component designed for the WG260 series and related heavy-duty powershift transmissions. This OEM genuine part, identified by SKU 0634.402.526, functions as a critical static seal between the transmission housing and the internal cover assembly. It prevents pressurized hydraulic fluid from bypassing the clutch piston circuits, ensuring consistent gear engagement and maintaining system pressure. The R-Ring sits in a machined groove on the TRANSMISSION HOUSING, creating a leak-proof barrier that withstands extreme thermal cycling and high-pressure oil flow. Without this seal, the entire hydraulic control system loses integrity, leading to performance degradation across the drivetrain.
Symptoms of Failure
- External oil seepage around the housing joint: A worn 0634.402.526 R-RING often manifests as slow hydraulic fluid leaks at the mating surface between the HOUSING and the COVER, visible as wet streaks or drips after operation.
- Intermittent gear slipping under load: When the R-Ring fails, internal pressure drops cause clutch packs to slip during torque transfer, particularly in higher gears of the WG260 series.
- Delayed or harsh shifting: Loss of seal integrity leads to air ingestion into the hydraulic circuits, resulting in erratic shift timing and noticeable clunking during gear changes.
- Overheating transmission fluid: A compromised R-Ring allows fluid to bypass cooling circuits, causing the oil temperature to rise rapidly during sustained operation.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number (SKU) | 0634.402.526 |
| Type | R-Ring (Static Seal) |
| Material | Nitrile Rubber (NBR) with fabric reinforcement |
| Inner Diameter | Approx. 140 mm |
| Cross-Section | 5.5 mm (round profile) |
| Weight | 0.045 kg |
| OEM Reference | ZF 0634.402.526 |
| Operating Temperature Range | -40°C to +120°C |
| Hardness (Shore A) | 70 ± 5 |
Compatibility
This R-Ring is engineered for ZF WG-series powershift transmissions, specifically the WG 250, WG 251, WG 258, WG 260, WG 261, WG 308, and WG 311 series. It is a direct replacement for the OEM seal used in the clutch housing assembly of these models. The part is also compatible with earlier WG180 and WG200 variants when used in conjunction with the correct HEXAGON SCREW torque specifications. Always verify the housing groove dimensions before installation, as variations exist between series.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4646101028 | TRANSMISSION HOUSING | Main structural casing housing all rotating assemblies |
| 4646301095 | HOUSING | Intermediate housing for clutch pack support |
| 4646301087 | COVER | End cover sealing the hydraulic control section |
| 0636015304 | HEXAGON SCREW | Fastener for housing-to-cover attachment |
| 0636101828 | CAP SCREW | High-tensile bolt for clutch drum retention |
| 4646301102 | COVER SHEET | Thin gasket plate for oil channel separation |
| 4646301098 | COVER SHEET | Secondary gasket for pressure regulation |
| 0730365125 | TYPE PLATE | Identification plate with transmission serial number |
| 0631311009 | GROOVED STUD | Alignment dowel for precise housing positioning |
| 0636101193 | CAP SCREW | Low-profile bolt for cover sheet fastening |
Authorized ZF Distributor
We are a certified supplier of genuine ZF components.
