7. COMBINED ARM AND TRAVEL OPERATION ARM CYLINDER BUCKET CYLINDER BOOM CYLINDER P5 P4 Pi2 Rs MU Pi1 Pn1 Pn2 TRAVEL MOTOR SWING MOTOR PBa P02 PAb1 PDb2 P04 A2 PUMP A1 PUMP PILOT PUMP HYDRAULIC TANK 330S3HC23 When the arm and travel functions are operated, simultaneously the arm spools and travel spools in the main control valve are moved to the functional position by the pilot oil pressure from the remote control valve and the straight travel spool is pushed to the right by the oil pressure from pilot pump.
The oil from the A1 pump flows into the travel motors through the RH travel spool of the left control valve and the LH travel spool of the right control valve via the straight travel spool. The oil from the A2 pump flows into the arm cylinders through the arm 1 spool and arm 2 spool via the parallel and confluence oil passage. When the pressure of the travel motors is lower than the pressure of the arm cylinder, some oil from the A2 pump flows into the travel motors through the check valve and orifice in the straight travel spool. This prevents the rapid slowdown of the travel. The arm is operated and the machine travels straight.
3-30 BC1 NRV2 Cck DR9 Co P05 Do PCo PDo OPTION Ca Da BC2 NRV1 Cco CoR AkR LCk1 LCk2 DoR LCo CaR DaR BUCKET BbkR DR7 CRa PaL ARM1 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 LCs AbR LCb CRb BOOM1 P03 DR3 Ctl Dtl PCtl PDtl SH Patt ( TR RIG AVH ET L) PS DR1 P01 PtrPS TS STRAIGHT TRAVEL SPOOL P03 DR3 Ctl Dtl PCtl PDtl Patt (RIGHT) TRAVEL DR1 BtR AtR (LEFT) TRAVEL MRV