2. MAIN CONTROL VALVE 2. MAIN CONTROL VALVE 6-21 Part name Inspection item Criteria & measure Block ·Existence of scratch, rusting or corrosion. · In case of damage in following section, replace part. - Sliding sections of casing fore and spool, especially land sections applied with holded pressure. - Seal pocket section where spool is inserted. - Seal section of port where O-ring contacts. - Seal section of each relief valve for main, travel, and port. - Other damages that may damage normal functions. Spool · Existence of scratch, gnawing, rusting or corrosion. ·O-ring seal sections at both ends. · Insert spool in casing hole, rotate and reciprocate it.
· Replacement when its outside sliding section has scratch (especially on seals-contacting section). · Replacement when its sliding section has scratch. · Correction or replacement when O-ring is damaged or when spool does not move smoothly. Poppet ·Damage of poppet or spring ·Insert poppet into casing and function it. · Correction or replacement when sealing is incomplete. · Normal when it can function lightly without being caught. Around spring · Rusting, corrosion, deformation or breaking of spring, spring seat, plug or cover. ·Replacement for significant damage. Around seal for spool ·External oil leakage. · Rusting, corrosion or deformation of seal plate. ·Correction or replacement.
·Correction or replacement. Main relief valve & port relief valve ·External rusting or damage. ·Contacting face of valve seat. ·Contacting face of poppet. ·Abnormal spring. ·O-rings, back up rings and seals. ·Replacement. ·Replacement when damaged. ·Replacement when damaged. ·Replacement. ·100% replacement in general.