5. COMBINED SWING AND TRAVEL OPERATION ARM CYLINDER BUCKET CYLINDER BOOM CYLINDER P5 P4 Pi2 Rs MU Pi1 Pn1 Pn2 TRAVEL MOTOR SWING MOTOR PBa P02 P04 PAb1 PDb2 A2 PUMP A1 PUMP PILOT PUMP HYDRAULIC TANK 330S3HC21 When the swing and travel functions are operated, simultaneously the swing spool 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 straight travel spool is pushed to the right by the pilot oil pressure from the 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 swing motor in the straight travel spool. When the pressure of the travel motors is lower than the pressure of the swing motor, 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 upper structure swings and the machine travels straight.
3-28 BC1 N RV2 Cck DR9 Co P05 Do PCo PDo OPTION Ca Da BC2 NRV1 Cco CoR AkR LCk1 LCk2 DoR OPTION LCo CaR DaR BUCKET BbkR aDR7 CRa PaL ARM1 LCa LCa2 ARM2 PAa2 DR6 a2 PCsp PDb2 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 STRAIGHT TRAVEL SPOOL Cs Ds PCs PDs DR5 SWING P03 LCs AbR LCb CRb BOOM1 DR3 Ctl Dtl PCtl PDtl Patt (RIGHT) TRAVEL DR1 BtR AtR (RIGHT) TRAVEL (LEFT) TRAVEL MRV