Overview
The ZF 0634.303.278 O-RING is a critical sealing component engineered for the WG100, WG130, and WG131 transmission series. This OEM genuine part, identified by SKU 0634.303.278, sits within the hydraulic control unit and valve body assembly, where it prevents pressurized transmission fluid from bypassing critical passages. By maintaining a tight seal between mating surfaces, this O-ring ensures consistent hydraulic pressure for smooth gear engagement and clutch application. When installed alongside the 4143101009 HOUSING or the 4143301025 HOUSING, it forms a leak-proof barrier that protects internal components from contamination and fluid loss.
Symptoms of Failure
- Transmission fluid puddles under vehicle: A worn 0634.303.278 O-ring often causes visible oil leaks around the valve body or housing mating surfaces, especially after the transmission reaches operating temperature.
- Delayed or harsh gear engagement: When this seal fails, hydraulic pressure drops, leading to sluggish shifts or abrupt engagement when moving from Park to Drive or Reverse.
- Erratic shifting under load: Drivers may notice gear slipping or hesitation during acceleration, as the compromised O-ring cannot maintain the required pressure for clutch pack application.
- Low fluid level without external damage: Internal weeping from this O-ring can cause gradual fluid loss without obvious external drips, triggering warning lights or erratic transmission behavior.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number (SKU) | 0634.303.278 |
| Material | Nitrile rubber (NBR) / HNBR |
| Inner Diameter | ~34.0 mm |
| Cross Section | ~3.0 mm |
| Weight | ~2 grams |
| OEM Reference | ZF 0634.303.278 |
| Application | Hydraulic seal between housing and valve body |
Compatibility
This O-ring is specifically designed for ZF WG-series transmissions, including the WG100, WG130, and WG131 models. It also fits select variants of the WG180 and WG200 series where the valve body and housing interface share identical sealing geometry. For proper installation, always pair this seal with the 0634313603 O-RING for adjacent ports and the 4475280018 SCREW PLUG to secure the housing assembly. Verify your transmission model and housing part numbers before ordering.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4143101009 | HOUSING | Main housing for valve body assembly |
| 4143301025 | HOUSING | Secondary housing for hydraulic passages |
| 0634313603 | O-RING | Seal for adjacent hydraulic ports |
| 4475280018 | SCREW PLUG | Threaded plug for housing sealing |
| 0501342341 | SUPPORT RING | Backup ring for O-ring retention |
| 4143298457 | SEAL KIT | Complete gasket and O-ring set |
| 0634313591 | O-RING | Seal for pressure regulator circuits |
| 0636101068 | CAP SCREW | Fastener for housing attachment |
| 4143221013 | THROTTLE VALVE | Hydraulic control valve for shift timing |
| 0634304484 | O-RING | Seal for throttle valve bore |
ZF 0634.303.278 O-RING – O-Ring RFQ Support
PartsZF helps B2B buyers source ZF 0634.303.278 O-RING with fast RFQ support, expert part-number lookup, documentation review, and export coordination. This O-ring page is built from confirmed catalog, media, and reference data to reduce sourcing uncertainty for construction machinery transmission parts.
Part-Number Summary
Use ZF number 0634.303.278 when sending your RFQ. PartsZF can review dotted, spaced, and compact number formats against the available product and documentation records.
Application Context
- Illustration section: INPUT HOUSING
- Illustration section: MULTIDISK BRAKE
- Illustration section: KIT REPAIR KIT
Cross Reference Support
- Cross-reference record available for RFQ review.
Specification Snapshot
| ZF part number | 0634.303.278 |
|---|---|
| Normalized SKU | 0634303278 |
| Part name | O-RING |
| Product category | O-ring |
| Cross-reference support | Available for RFQ review |
| Weight | 0.005 |
Image and Documentation Notes
Current product media status: fallback. Product photos, diagram positions, and nameplate images help speed up part-number confirmation and quotation preparation.
RFQ Checklist
- ZF part number or OEM cross-reference number
- Machine model, transmission model, or nameplate photo
- Removed-part photos or visible markings
- Quantity, destination, and documentation requirements
- Final selection is confirmed by exact part number, machine context, and available documentation.
Related Parts
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- ZF 0634.306.523 O-RING
- ZF 0634.306.213 O-RING
- ZF 0734.313.134 O-RING
- ZF 0634.313.728 O-RING
