Product Overview — Part 6129902
The 6129902 is a precision-manufactured Engine Cushion / Rubber Mount component for demanding industrial and heavy equipment applications. Rear engine mounting rubber cushion for Hitachi excavators. Provides controlled stiffness characteristics to minimize low-frequency vibration transmission.
As the rear mounting point for the Hitachi engine assembly, part 6129902 must manage combined vertical and horizontal loading under dynamic engine firing forces. The compound formulation incorporates a carbon black reinforcement system tuned to provide a natural frequency well below the engine idle frequency, ensuring effective vibration isolation across the operational speed range. The rear cushion works in conjunction with the front mount 1524771 to form a complete two-point isolation system.
Browse related products: 1524771, 6180100, 1487116, 8A31-54-1110 for complete engine cushion system maintenance solutions.
Technical Specifications
| Property | Value | Standard |
|---|---|---|
| Part Number | 6129902 | OEM Specification |
| Hardness | 60 ± 5 Shore A | ISO 48-4 / ASTM D2240 |
| Tensile Strength | ≥ 18 MPa | ISO 37 / ASTM D412 |
| Elongation at Break | ≥ 350% | ISO 37 / ASTM D412 |
| Compression Set | ≤ 25% (22h/70°C) | ISO 815-1 / ASTM D395 |
| Temperature Range | −40°C to +100°C | Operational limits |
| Ozone Resistance | No cracking 168 h | ISO 1431-1 |
| Fire Safety | EN 45545-2 HL2/HL3 avail. | EN 45545-2:2013 |
| Fatigue Life | >1,500,000 cycles | Dynamic fatigue test |
| Bond Strength | ≥ Bulk rubber tear | ISO 813 |
Applications & Compatibility
Hitachi EX200, EX200-2, EX300, EX400; ZX200, ZX230, ZX270, ZX350 series excavators. Compatible with Hitachi medium and large crawler excavators.
Our engineering team can confirm compatibility for other equipment types not listed above. Contact us with the make, model, year, and serial number for precise cross-reference verification before ordering.
Material & Quality Standards
- Base Polymer: Natural Rubber (NR) or NR/SBR blend — outstanding resilience and low heat buildup
- Reinforcing Fillers: High-structure carbon black for controlled stiffness and abrasion resistance
- Protection Additives: Anti-ozonant wax and chemical antioxidant system for extended outdoor service life
- Bonding System: Chemically bonded rubber-to-metal interface with bond strength exceeding bulk rubber tear strength
- EN 45545-2 Option: Halogen-free flame retardant meeting smoke toxicity requirements for railway-grade applications
All production batches manufactured under ISO 9001:2015 QMS with full material traceability from raw compound to finished product. Certificates of conformance and material test reports supplied on request.
Installation & Maintenance
- Verify on arrival: Confirm part number 6129902. Inspect for transit damage or surface defects — reject any non-conforming item.
- Prepare mating surfaces: Remove all rust, old rubber residue, grease, and loose paint. Flatness tolerance within 0.5 mm for proper seating.
- Correct orientation: Follow the assembly drawing or OEM workshop manual. Incorrect orientation causes premature failure and may void warranty.
- Torque fasteners: Use a calibrated torque wrench with a cross-pattern tightening sequence to the OEM-specified value.
- Post-installation check: Inspect for correct seating and gap clearance. Run equipment at idle to confirm absence of abnormal noise or vibration.
Recommended replacement interval: 3,000–5,000 operating hours or at first sign of cracking, permanent deformation exceeding 3 mm, or detachment of rubber from metal insert.