Our high-performance SB121 hydraulic breaker rubber cup diaphragm, standard OEM-grade Soosan SB121 accumulator seal, core functional SB121 nitrogen isolation rubber cup, essential aftermarket excavator breaker sealing spare part, universal SB121 OEM replacement membrane and rugged heavy-duty hydraulic hammer rubber seal, is specially engineered for Soosan SB121, SB121TS, SB121TR full-series hydraulic rock breakers matching 28~35 ton heavy excavators. Manufactured from modified high-performance HNBR hydrogenated nitrile rubber via one-piece seamless hot vulcanization, this bowl-shaped sealing component installs inside rear-head accumulator chamber to completely separate high-pressure nitrogen and hydraulic oil, store instant striking potential energy and stabilize continuous hammer impact power. Strictly replicated per original OEM mold size for plug-and-play replacement, effectively fix common equipment faults including nitrogen leakage, internal oil-gas mixing, insufficient striking force and frequent repeated nitrogen refilling caused by aging, crack or rupture of original cup seal. Constant in-stock supply for global quarry operators, demolition contractors, machinery repair garages and international construction machinery spare parts distributors worldwide.

1. Incoming raw rubber inspection: chemical composition, tensile strength & compression set testing, reject inferior recycled rubber raw material.
2. Multi-stage closed internal mixing: evenly disperse anti-aging, oil-resistant, anti-tear functional additives inside rubber base.
3. OEM dedicated precision mold constant-temperature constant-pressure seamless hot compression vulcanization molding.
4. Post-vulcanization constant-temperature curing standing to release rubber internal forming residual stress.
5. Full manual appearance inspection one by one, screen out products with pinhole, hidden crack, irregular deformation.
6. Random sampling inspection: inflation air tightness test + reciprocating expansion fatigue durability test.
7. Qualified finished product surface dedusting, independent sealed packaging into warehouse.

• Direct replacement spare for failed original cup diaphragm during SB121 hydraulic breaker overhaul maintenance.
• Fix typical breakdowns: slow striking frequency, weak impact force, frequent nitrogen inflation, rear head abnormal oil leakage.
• Regular preventive spare parts for 20~30t excavator fleets equipped with SB121 hammer in quarry mining, highway demolition, municipal reconstruction projects.
• Bulk stocking consumable item for global construction machinery spare parts wholesalers and local excavator repair shops.
• Suitable for hard rock mining, concrete demolition, foundation breaking, terrain leveling heavy construction scenarios.