8231120698 OVERCENT VALVE Seal kit for Atlas Copco Boomer 281 Hydraulic Rock Drills

Heavy-Duty Overcentre Valve Seal Repair Kit for Atlas Copco Boomer 281 Underground Rigs | OEM Part: 8231120698

Critical Valve Safety & Operational Performance

In underground tunneling and face drilling, overcentre (counterbalance) valves play a vital load-holding safety role on the Atlas Copco / Epiroc Boomer 281 rig. They control overrunning loads, lock hydraulic pressure in boom/feed positioning circuits, and prevent catastrophic component drop in the event of a hose burst or pressure drop.

When valve internal O-rings and backup rings degrade from high thermal friction and oil contamination, fluid bypasses the valve spool. This leads to boom drift, shaky positioning control, slow pilot response, and external valve block weeping. Our 8231120698 Overcentre Valve Seal Kit restores original hydraulic lock-holding pressure and smooth pilot modulation.

Technical Specifications & System Compatibility

• Brand & System Compatibility: Atlas Copco / Epiroc Mining & Excavation Equipment

• Target Machinery Application: Atlas Copco Boomer 281 Face Drilling Jumbo Hydraulic Circuits

• Component Type: Hydraulic Overcentre / Counterbalance / Load-Control Valve

• Primary OEM Part Number: 8231120698 (Cross-ref: 8231 1206 98)

• Internal Catalog SKU: 8231120698-VALVE-281

• Material Composition: High-Spec Viton (FKM) + Heavy-Duty NBR + Anti-Extrusion PTFE Backup Rings

• Dynamic Pressure Rating: Designed for continuous load holding and peak spikes up to 350+ Bar (5075+ PSI)

• Temperature Endurance Range: -30°C to 120°C (-22°F to 248°F)

Key Material Science & Performance Features

• High-Temperature Viton (FKM) O-Rings: Resists thermal degradation and chemical attack, maintaining elastic recovery even when hydraulic oil temperatures spike during non-stop drilling shifts.

• Anti-Extrusion PTFE Backup Rings: Prevents elastomer nibbling and seal blowout under ultra-high pilot pressure spikes and static load clamping.

• Resilient NBR Elastomers: Provides superior flexibility and dynamic radial sealing to maintain a tight seal against continuous vibration.

• Contamination-Resistant Sealing Lip Profiles: Blocks fine particles and degraded hydraulic sludge from entering valve spool tolerances, eliminating valve stickiness.

Maintenance & Service Advice for Fleet Technicians

💡 Jobsite Maintenance Tip:

Hydraulic overcentre valve spools feature extremely tight machining tolerances. When rebuilding the valve using the 8231120698 seal kit, thoroughly clean the valve cartridge body in a solvent bath before removing old O-rings. Use non-marring brass or plastic picks to remove degraded seals to prevent scratching the fine seal grooves. Always coat new FKM O-rings and PTFE backup rings with clean hydraulic oil during reassembly to avoid pinches during cartridge insertion.

Q&A

• Q: Is part number 8231120698 interchangeable between Atlas Copco and Epiroc brands?

  A: Yes. Epiroc is the dedicated mining division formerly under Atlas Copco. Part number 8231120698 / 8231 1206 98 matches identical factory specifications across both designations.

• Q: What are the main failure symptoms of a worn overcentre valve on a Boomer 281?

  A: Common symptoms include boom or feed cylinder creep (hydraulic drift), jerky boom lowering movements, loss of load-holding capability, or visible hydraulic oil leaking around the valve cartridge manifold.