When carrying out the combined operation of swing and boom up, the boom up operating speed is lowered then normal operation. To increase working efficiency, swing speed reducing system is used. The pilot oil from pilot pump flow into P03 port in main control valve through boom priority EPPR valve. P03 oil pressure moves swing reducing spool to lower position and oil flow rate to the swing motor decreased. Then, the boom up speed is increased. This is called the boom priority system. The boom up speed can be adjusted by the cluster. Refer to page 3-19 of the operator's manual. 3-9 3.
BOOM PRIORITY SYSTEM LA INR DM RB U C K E T EB O O M C Y E R C Y L IN D E C Y L IN D R MU Pi2Pi1 P5 RsP4 Pn1 Pn2 T R A V E L M O T O R PCbc BC1 PDbc NRV2 Cck DR9 BC2 NRV1 Cco Co CoR Bk Ak P D0 o5 AkR PCo DoR P04 PBk PDo PAk OPTION BUCKET PCbc LCo LCk1 LCk2 Ca CaR Da DaR BbkR PBaDR7 CRa PaL PBa2 PCa PAa2 S W IN G M O T O R PDa ARM1 LCa LCa2 ARM2 DR6 Boom speed PAa2 P02 PBa Ccb LCar Abk PCsp PBrc PDb2 BOOM2 SWING P/R ARM REGEN DPA Rb 4k LCbk BbR Bb Swing C Ds r se pd ou oc ling PDA bRb L2 AbR CRb P02 s P04 PCs PBb1 PDs PAb1 DR5 SWING LCs LCb BOOM1 PDb2 P03 DR3 Btr Ctl BtR Atr PD Ctl tl AtR PBtr PDtl PAtr SH Patt ( TR RIG AVH ET L) T(L RE AF VT E) L RCV PEDAL P T TRAVEL PS DR1 V2 P01 PtrPS TS MRV T1 P1 P2 Pu (2) (1) (4) (3) PAtr PBtr PDtl PCtl Dr#, dr# SWING P T ARM BUCKET P T BOOM A 2A 1 PP MILO PT P P U M PU M P U BOOM PRIORITY EPPR VALVE P03 P Pu (MCV) (T/Joint) (MCV) (1) (3) (2) (4) (3) (1) (2) (4) A B D E F G H J A5 A3 A2 A1 P4 P01(MCV) P3 PG(S/Motor) P2 Psv(Pump) H Y D R A U LIC T A N K a c b d e2 e d1 f g h h1 j h2 P(2-EPPR valve) PS PS PS T PCs PDs PCa PAk PAb1 PBb1 P1 LINE FILTER PCsp PS PS PS PDa PBk 330S3HC0 4 BC1 N RV2 Cck DR9 Co P05 Do PCo PDo OPTION Ca BC2 NRV1 Cco CoR AkR LCk1 LCk2 DoR P04 PBk PAk PCbc PBa2 PAa2 DR6 P02 PBa Abk PBrc PAbk DR4 LCo CaR BUCKET BbkR Da DR7 CRa PaL ARM1 DaR BbkR LCa LCa2 ARM2 PAa2 DR6 Csp Db2 BOOM2 Ccb SWING P/R LCar LCbk BbR ARM REGEN P02 Abk PBrc PAbk DR4 Cs Ds PCs PDs DR5 SWING P03 DR3 Ctl Dtl PCtl PDtl SH Patt ( TR RIG AVH ET L) PS DR1 P01 PtrPS TS Cs Ds PCs PDs DR5 SWING Swing reducing spool LCs AbR LCb CRb BOOM1 P03 DR3 Ctl Dtl PCtl PDtl Patt (RIGHT) TRAVEL DR1 BtR AtR (RIGHT) TRAVEL (LEFT) TRAVEL BUCKET P T BOOM BOOM PRIORITY EPPR VALVE P03 P Pu (MCV) (T/Joint) (MCV) (3) (1) (2) (4) F G H J A5 A3 A2 A1 (3) (1) (2) (4) F G H J