Counter Balance Valve Comparable Replacement to Sun Hydraulics CBCA-LAN The check valve allows free flow from (port 2) to (port 1) while a direct-acting, pilot assisted relief valve controls flow from (port 1) to (port 2). Pilot assist at (port 3) lowers the effective setting of the relief valve at a rate determined by the pilot ratio. 16GPM/4000PSI Ratio 3:1 Preset 3000PSI Check: 4PSI