3112393 Original Loader D-RING for ZW140-5B ZW220 ZW310-6 

Part number 3112393 is the official part number for the O-ring of Hitachi's original loader, belonging to the 31XXXXX seal/rubber component classification in Hitachi's original part number system. As a Hitachi original factory standard seal, it is widely used in the hydraulic, transmission, and oil systems of Hitachi ZW series wheel loaders (such as ZW140, ZW180, ZW220, ZW250, ZW310, ZW370, etc.) - typical installation positions include hydraulic control valve block joints, pump/motor housing joint surfaces, steering/brake system oil circuits, and static sealing grooves of transmission cooling return circuits.

As a Hitachi original O-ring, its essence is an elastic seal with a circular (O-shaped) cross-section, which relies on the compression deformation in the groove during assembly (compression rate of about 15% -25% static seal) to fill the micro unevenness, thereby achieving bidirectional sealing and zero leakage. The O-rings used in hydraulic/oil circuit environments of Hitachi loaders are usually made of nitrile rubber NBR (Buna-N) or fluororubber FKM/Viton, with a hardness of 70-90 Shore A to balance elasticity and extrusion resistance; The working medium is mainly mineral based hydraulic oil/gear oil/transmission oil, with a temperature resistance range of approximately -35 ℃ to+120 ℃ for NBR and -20 ℃ to+200 ℃ for FKM, and can be equipped with retaining rings for higher pressure zones according to working conditions.

O-ring is a disposable sealing component and is generally "disposable upon disassembly". It is strictly prohibited to reuse it. In daily maintenance: ① When leakage is found, do not just "tighten the joint" - clean the surface first to confirm whether the oil stains are really leaking from the joint surface; ② When replacing, the bottom and side walls of the groove must be thoroughly cleaned to remove old rubber residue, grease deposits, and metal shavings. If the groove is bumped, scratched, or deformed, it should be repaired or replaced with a cover plate/valve block first, otherwise the new ring will also be cut; ③ Before installing a new ring, a thin layer of lubricating grease compatible with the working medium (such as a small amount of silicone grease/lithium based grease) can be applied to the surface of the ring to lubricate and prevent curling edges, but it is absolutely not allowed to wipe the ring with liquid containing solvents